77
THE EFFECT OP A VARIABLE DRA.P'l 'lUBE FLOW AREA ON 1'8 PERFORMlBOE OF A REACTION TURBINE b7 BLISS DEAN 'RAY A THESIS submitted to OREGOI' S'l'A!E OOLLEGE in putlal tultlllment ot th-e requ1remente tor the degree ot MASBR OF SOIEWOE June 19.$7

The Effect of A Variable Draft Tube Flow Area on the

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Page 1: The Effect of A Variable Draft Tube Flow Area on the

THE EFFECT OP A VARIABLE DRAPl lUBE FLOW AREA

ON 18 PERFORMlBOE OF A REACTION TURBINE

b7

BLISS DEAN RAY

A THESIS

submitted to

OREGOI SlAE OOLLEGE

in putlal tultlllment ot th-e requ1remente tor the

degree ot

MASBR OF SOIEWOE

June 19$7

Srr[ ffiHttlf f nralE

ffi frurld rr TmS fir6

Ioryw lltDilr0 I0 rfrq

Redacted for Privacy

rilE 0 r4mrro lmur rs ur-Ttqamp

Redacted for Privacy

trfrrryIlW ITITS ge lumrrE silrfrtHt

Redacted for Privacy

mftr o r8rne uf ffrTo Jc iprmJHa

Redacted for Privacy

rffilgtrIIY

or the many persona who have shown interest and

offered assistance in the progress or this investigation

certain ones merit special acknowledgment

In particular gratitude is expreased toward H G

Barnett Head or the Depaltment of Electrical Engineering

L N Stone Associate Professor of Electrical Engineering

and w H Paul Profeasoll of Automotive Engineering tor

their generous supply ot advice and equipment J R H Shoebull

maker Jr Assistant Professor of Civil Eng1neering for

his help and photographic work G w Holcomb Chairman or the Department of Oivil Engineering and w c Weatgarth

Assistant Professor of 01vil Engineering for thea

cooperation and assistance in obtaining material and

auppllea J Thomas B Hayes and Vtetor N Bredbullhoett ot the

oonaulting engineering firm or Cornell Howland Raybullbull and

Merryfield for their suggestions and encouragementJ H D

Pritchett tor the photoglaph1c duplication B K Scoggan

R D Smith D D Sweeney R M Elder R L Polv1 and

W H Knuth ror their b1releaa ettorts in the taking ot

data and Mra Jeanne Nepoundf for her patience in t he typing

ot the final draft ot the thesis

lb1a investigation could have been neither started

nor finished without the inapirat1on1 ideas and criticisms

of Fl-ed Merryfield Professor ot Sanitary Engineering to

whom a special debt is owed

Grant Robley Aas1stant Dean or t he School of Engibull

neering or Yal Un1ver ity ia the cause or it all

Arl1sa D Ray

bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull

bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull

bull bull bull bull

bull bull bull bull bull bull bull bull bull bull

bull bull bull bull bull bull bull bull bull bull bull bull bull

TABLE Qf CONTENTS

Chapter

I INTRODUCTION bull

A Purpose and Scope of Investigation bull bull bull bull l B Reaction Turbinea bull bull bull bull bull bull bull bull bull bull bull bull 2 C Draft Tubes bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull 5

II DISCUSSION OF TURBI NE LOSSES bull bull bull bull bull bull bull bull 1

A General bull a Shock Loae ~ c Exit Loss 12

III PROPOSAL OF ALTERNATE METHOD OF CONTROL bull bull bull bullbull 14 A Type and Location of Control bull bull bull bull bull bull bull B Estimated Eftect on Actual Turbine bull bull bull bull ~ c Requirements tor Teet Verification bull bull bull bull 19

IV APPARATUS AND METHODS OP TESl bull bull bull bull bull bull bull bull bull 23

A Equipment bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull 23 B InatlWilentation and Measuring Devicbullbull bull bull 26 c Operational Pz-ocedure bull bull bull bull bull bull bull bull bull bull 26 D Schedule ot Rune bull bull bull bull bull bull bull bull bull bull bull bull bull JS

v DATA bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull 37

A Original Data bull bull bull bull bull bull bull bull bull bull B Calculated Data bull bull bull bull bull bull bull bull bull bull bull bull bull ~A

VI TEST RESULTS bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull 44 A Presentation of Results bull bull bull bull bull bull bull bull bull 44B Discussion of aeaults $1

VII CONCLUSIONS bull middot 56bull bull bull bull bull bull bull bull bull bull bull BIBLIOGRAPY bull bull bull bull bull bull bull bull bull bull bull 51 APPENDICES bull bull bull bull bull bull bull bull bull bull bull 60

A lfotation bull bull bull bull 61 B Original Data bull bull bull bull bull bull bull bull bull bull bull bull bull bull 6)c Calculated Data bull bull bull bull bull bull bull bull bull bull bull 67

bull bull bull bull bull bull bull bull bull bull bull

bull bull

bull bull

LIS~ OP_ __ ILLUSTRAfiOBS-middot

Fiere Page

1 13 $ Inch Reaction turbine bull bull bull bull bull bull bull bull bull bull 4

s bull bull bull bull bull bull bull bull bull bull bull bull

Plow Area bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull 4S

2 Turbine Runner Vector D1agrama and Shook Loaa Diaptama bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull 10

) Turbine PertoPmance CurYea bull bull bull bull bull bull bull bull bull bull 20

4 General View ot Teat Equipment bull bull bull bull bull bull bull 21

6 View ot Teat ut-bine bull bull bullmiddot bull bull bull bull bull bull bull bull bull 7 Teat Generator and Platform bull bull bull bull bull bull bull bull bull 27

8 Iutrument Board and Field Rheostat bull bull bull bull bull 27

9 Vlev ot Water lUteoatat bull bull bull bull bull bull bull bull bull bull 29

10 View or Water Rheostat bull 29

11 Vater Plow Diagram and Electrical Laout bull bull bull 30

12 Sketoh ot Draft ltlbe and Teat Inaerta bullbull bull bull 33

13 View ot Dratt Ube Inaer bull bull bull bull bull bull bull bull bull bull 34

14 Vlev ot Dr~t lube Iuert bull bull bull bull bull bull bull bull bull 34 lS Curves ot Generator Voltage Drop and Copper

Lose bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull 40 16 euvtee of Oenerator Stray Power Lobullbull bull bull bull 41 17 Turbine Charae ter1at1ca with lOOC Dl-att lUbe

18 Turbine Characteristicbull With 7SC Draft tube Flow Area bull bull bull bull bull bull bull bull bull bull bullbull bull bullbull 46

19 Comparleon Between 7S~ and 100 Pratt Tubbull Flow Areas ot Power and Etf1c1ency at OVer Gate Condition bull bull bullbullbull bull bullbullbullbullbullbull 47

bull bull

~ Q ILLt1SlATlOIS (Continued)

F1pe

20 Comparison Between 15 and 100~ Draft Tube Flow Areas of PoweP and Ett1c1enoy at Halt Gate Condition bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull 46

21 Oompu1aon Betwen S~ and 100~ Draft Tube Flow ANaa ot Po-r and Efflctency ab Ovbullbull Gate Condftimiddoton bull - bull bull bull bull - bull bull middot bull bull bull 49 Compar1aon ot Spec1tic Speeda tor 75~ middotand 10~ Draft Tube Flow Areae bull bull bull bull bull bull bull bull so

I

bull

filE EPPEOI OF A VARIABLE DRAFT TUBE FLOW AREA

ON THE PERFORMANltJE OF A REAOTIO TURBINE

Chapter l

IITRODUClIOH

A hrpose and Scope of Invst1pt1on

Present day control of reaction turbines is accombull

pl1ahed by the use of wicket gates immediately- preceding

the turbine runner These gates otter an interrelated conbull

- trol to the quantity and direction ot the water entering

t-he runner ie a change in the amount ot flow will rebull

middot ult in a change in direction This combined control leada

to loesee at all but the rated or design condition ot the

turbine (2$ Pbull )71)

This investigation dealt with an att mpt to better

turbine performance at all points of operation b y the

eatabliahment of separate controls over the rate of flow

and the d1J~ect1on ot the entering watebullbull

The only physical modification of the test tlutbine

was the insertion of flow restricting device in the dratt

tube

Ot primary interest were the trends in the change of

2

turbine performance with the amount ot draft tube tlow

area To this end complete turbine charaeteristiea were

not obtained tor 0ach device inserted in the draft tube

It was considered sutt1e1ent to obtain data tor the tull

speed range tor two representative gat openings one

greater and one less than the rated gate openingbull

Before proceeding with th report ot this 1nvest1gabull

t1on it 1a desirable to supply sa b ckground m terial

on reaction tw-blnes and their dratt tubes

B Raot1on 1rbinea

A hydraulic turbine is a device for converting the

energy in water to eohanical energy (6 Pbull 93lbull96S) furbull

b1nes may be loosely grouped into one of three elasse

impulsmiddote 1 reaot1on or propeller

An impulse turbine normally operates under a high head

and with a relatively sma~l amount ot watel in the converbull

sion or kinetic nergy to mechanical energy The propeller

turbine utilizes pressure energy to develop mechanical

energy while under a low head and p ss1ng a large amount of

waver

The reaction turbine lies somewhere between these two

extremes It changes both pressure and kinetic energy

while oper ting under a medium head with a moderate ount

opound water An example or a reaction turbine is pietur d in

Figure 1

lhe terms of high low small and so tomiddotrth are only

relative in sense A turbinebulls class1f1 eat1on is depenfent

upon its hoad rate of diacharge and speed of rot tion A

useful index tor turbine comparison (5 Pbull 825) is termed

specific speed and this ia a function of the rated ipeed

power output and head or the turbine The common range in

values ot speoitic speed ($ Pbull 826 ) tor each type ot tlirshy

bine is

Impulse J to SS tor one nozzle)Reaction bull 22 to 80 Propeller - 85 to 170

The development of t he reaction turbine began in the

early part or the nineteenth century (26 Pbull 1217bull1)6)

The trst efficient inward tlow turbine was de igned by

James B Francis an American in 1649bull For many years

turbine design was a matter of cutbullandbulltry in America an4

pure mathematical analysis 1n Europe It was not until the

two schools began exchanging ideas in the l$tter halt ot

the n1neteenth century that pronounced advancement was made

in the field

ObTioual7 the primary pux-pose ot any turbine inatallabull

t1on is t he production of power Added to this is the

restriction that the production or power must necessarily

be a controlled process An example of this is where the

turbine is direct-connected to an electric generator which

4

Figure 1 - 135 Inch Reaction Turbine

5

must operate at a constant speed or rotation even though _

the power demand ohangos In thiamp case the turbine nuet

be eap~able or producing a range of power output yet menshy

ta1n e eonetant speed

Speed regulation of the turbine iv accomplished by

means ot a governor (23 Pbull 24bull3-7) bull The contr-ol or regulashy

tion 1s indirect that i s the governor actually exereiaabull

control over the water in order to JJaintain e given speed

Co-ntrol over- the turbine end bence its speed and

power is the function ot a ring of movable wicket gates

located just upsttteam of the turbine runner These w1eket

gates 1n the process of opening and closing upon eeeh

0~1ar in a rotational manner actually control the amount

velocity and direction of tne water passing throu~~ them

C Draft Tubes

It has been found that the effeetive head on a reae

1l1on middotturbine is increased with the addi timiddoton of a draft tube

(3 Pbull 256bull264) Tne draft tube does thin by~

(1) Making a greater presaure d~op across the turbine

possible by the creation of a negative pressure at the

discharge or the runner and

2) DeoreaGing the k1net1e energy lost by increasing

the eross sectional area at exit

he draft tube permits the turbine runner to be

6

located above the tail race water surface without the

sacrifice of head However cavitation will cause pitting

of the turbine if the difference in elevation is too great

A common maximum elevation difference is 19 feet although

this figure is quite subject to modification between difshy

ferent installations (3 p middot 264-266)

There are many different types or draft tubes in use

today the choice or type being largely a matter or

economics (2$ p 368-370) A very common type particushy

larly among the smaller units is vertical with flaring

sides However the angle of flare is limited by the possishy

bility of separation of the flow from the sides In order

to achieve a certain discharge area the length of the tube

may be such as to require a great deal of excavation In

oases or this sort the cost of this excavation must be

balanced against a more elaborate design that does not

require as much excavation Other draft tubes in use

include the elbow hydracone and spreader types

Despite the differences found in construction and

design the draft tube must accomplish the desired objecshy

tives while offering a good hydraulic geometry to the flow

passing through it An inefficient draft tube defeats its

own purpose

Ohapter II

DISCUSSION ~ TURBINE LOSSES

A General

lhe head that 1a actually utilized by the turbine 1a

less than the effective bead as defined by equation ($) by

the amount that 1a lost due to mechanical and hydraulic

reasons

Mechanical loaaea are a function or the turbine 8p$ed

fhis ia not a lineaz- function but varies eomewhere between

N and N2 (3- Pbull 224)

Hydraulic losses encounteled in turbines ma- be subshy

divided aa to the location or occurrence (3 p 225-227) aa

fOllOW$S

(1) Penstock and scroll case

(2) Wicket gates

(3) Between wicket gates and turbine runner

(4) Runner passages

(5) Runner exit into draft tube

(6) Draft tube and

(7) At exit from the draft tube

The flow in the penstock scroll case wicket gates

runner passages and draft tube may be envisioned as

examples of flew in conventional pipes elbows and convergbull

1ng passages If this comparison may be made it could be

assumed that the losses encountered in these locations

would be proportional to vn ~ value ot N is normally2g

aesU111ed to be 2

he losses encountered between the wicket gates an4

the turbine runner and exit lossos are special cases which

will be discussed separately

B Shock toes_

The flow betwe n the wicket gat outlet and the runner

blade entrance is or particular 1nt rest because no direct

comparison vith common flow situations is obvious

Conaider the vector diagram (7 Pbull 7576) in Figure 2

The veetoo v1 is the absolute entering velocity of the

water and is fixed in magnitude and direction by the setbull

ting or the wicket gates The vector l11 1e the peripheztal

velocity of the runnel which tol any given turbine 1e

dependent only upon the turbine rotational speed The

combination of these two vectors ylelda the third vector

v1 which is the relative entering velocity ot the water

nere is only one setting ot the wicket gates for a

given turbine a peed that will produce an angle B1 which

coincides with the blade angle B1bull At other gate settings

the vector v1 will rotate and change in magnitude in such a

9

t ehion that B1 will beoome either greater or 1 sa than B1bull Th1 give rise to tbe phenomenon term d shock loasft

If B1 1a greater than B1 the relative ent ring veloebull

ityt v1 will have a compon~nt opposing the forward motion

of the runner The shock loss could be typified bullbull that

occasioned by direct impact or the water 0n the blade- If

E1 is lese than a] the vector l will overshoot the blade

and the flow will tend to eddy around the forward portion

or the blade tip

The shock loss can then be either due to impact or

eddying flow Since the area norm 1 to the radius at outlampt

of the w1eket gftee is essentially equ 1 to the area normnl

to the rad1u~ at the inlet to the turbine runner the combull

ponents ot vl and vl perpendicular to ul will b approxishy

mately equal This leads to the conclusion that xxbull ~epresenting the shock vector 1 parallel to Ulbull

For either the impact or eddy case the trigonometric

law of $1nee leads tot

XX

bull ul - sin (Bi-Al) vl eln Bi

It it 1a assumed that the energy lost in the shock 1a

the Telocity head ot the shock component XX then

10

VELOCITY VECTOR DIAGIWI

TYPES OF SHOCK LOSS

xbull X

IMPACT BDDJ

XX 1a Teloc1t7 caponent ot shock

Figure 2 - ~bine Runner Vector Diagram$ and Shock Loss Diagrams

11

2 shock loss (XX gt2g

C =sin (BimiddotAl)Let (1)sin Bi

(UlmiddotCV1)2Then shock loabull (2)- 2g

For a given gate opening C ia a constant ranging

from about 14 to 10 For a well designed wheel it is to middot

be expected that C would be approximately equal to U1V1

at rated conditions ie at point of maximum efficiency

This point will occur in the neighborhood of 3~ to 78

gate opening for moat turbines For overgate conditions

the angle A1 becomes larger so the value of C would

decrease For gate openings below rated conditions t he

angle A1 decreases and C would decrease One could expect

a fairly uniform decrease in t he value of C as the gate is

closed from t he overgate position

The velocity v1 is approximately constant for any

turbine speed since the area and rate of flow both decrease

fairly uniformly However for a given gate opening the

velocity V1 will decrease with increased turbine speed

From the foregoing comments and equation (2) the

following trends can be established

(1) For constant turbine speed the shook loss curve

will be close to parabolic in shape concave upward and

have its maximum near t he point of complete gate closure

--

12

and its minimum near the rated gate position

(2) For conatant gate opening the shook loss curve

will approximate a symmetrical parabola with its vertex

the point of minimum loas located at the rated condition

of operation (7 Pbull 79)

c Exit Loas

It can be seen from Figure 2 that the exit loss from

the turbine would be v222g if no draft tube were present

The addition of a draft tube permits the gradual reduction

of velocity by an increase in cross sectional area between

the exit of the runner and the exit from the draft tube

The exit loss and the frictional loss encountered in

the draft tube may be placed together in the expression

m va2 (3)Exit Loss ~---2g

For the ideal case of no friction in the draft tube

m is equal to the square of the ratio of the area at exit

from the runner to the area at exit from the draft tube

In an actual turbine installation however friction

will change the value of m (7 p 84-85) to somewhere

between that for the ideal case and a maximum ot 10

In the interest of maintaining a minimum exit loss

the turbine should be designed and operated so the velocity

V2 will be minimum This will occur when the discharge

13

vector is at right angles to the tangent to the runnerbull

ie the angle A2 1e ninety degree bull It ia to be expected

that this condition will be tultilled near the design con~

d1t1ons ot the ~bine

Current design praetiee 1 to have a small component

ot v2 in th$ direction of turbine rotation at rated condibull

tion$ ltS p 938)

For a constant turbine speed the d1seharg or exit

loss is ess nti lly a constant

For a constant gate opening the exit lo s curve is

aptrroximately a symmetrical pa~abola with ita vert x the

point or minimum loss located at a slightly lowe~ speed

th n the turbine rated speed (7 Pbull 79)

Chapter III

PROPOSAL OP ALlERMAlE MFTBO 0 CO TROL-A lz ~ Location 2 Control

Thua tar only practice and theoretical aspects appemiddotrbull

taining to present day turbinea have been d1acuaaed It

haa been presented that control over the ~bine ia ezerbull

oiaed b y manipulation of the wicket gatea located 11101led1bull

ately preceding the runner These gate - upon rotation

modify both the magn1tu4e and the direction ot the entering

velocit7 Moreover it has be n shown that a simultaneous

change in these two variables leads to inefficient operabull

tion by the introduction of shock loss he farther the

point of operation a from the rated conditione the more

aerioua ia the ahock loss encountered

Any attempt to better turbine pertorance at other

than rated conditione and tbne flatten the top ot the

etticieney hill8 must concentrate upon the lessening ot

the ahock loaa It 1a a aumed that 1 provement in the

scroll case gates and runners would lequ1re sueh pertecbull

tion 1n machine work and metal$ as to be prohibitively

expensive

It ie surmised that any move to elblinate eYen parbull

tially the shock loss would require separate control ovel

l$

the flow and gate exit angle Since it is improbable that

d1~ect1on could be controlled at any location other than

where the gatea are situated in current turbines it will

be assumed that guide vanes will be necessary regardlesa or the method used to control the rate of flow

The primary purpose ot th se guide vanes 1s that or control over the direction ot the incoming water They

should be free to rotate in much the same manner as ordibull

nary wicket gates in order to exercise control over th

turbine speed

If the rate ot tlov is to be controlled elsewhere it

must be modified either in the penstock or the draft tube

Devices that could be used are standard valves gates

variable orifices variable venturi sections and associated

flow regulating schemes

Alauming it were decided to locate such a device upbull

stream of the turbine it would be necessary to allow disbull

tance tor the flow picture to become reestablished prior to

entry to the turbine A contused flow making transit of

the turbine passages would only contribute additional loesbull

ea Such a distance allowance would be perbapa 20 to So

diameters (2$ Pbull 119-123) In large penstocka th1a would

repreaent a considerable distance Which from the viewbull

points ot convenience and control would be undesirable

Attempts to ascertain the effect or additional tlov

16

reduc ion at the wicket gatctsmiddot wae ade 1n the lfadraulioe middot

Laboratory of Oregon St middot te College in 1933 (20) Three

d1tterent thode ot reducins the tlow were t~ied

(l) Locking in the cloeed position pairs or wicket

gatea located opposite to eaeh o~er on the -periphery ot

the wheel

(2) Locking adjacent gates in an open position by

inserting blocks of wood between them and

()) Suocess1vely looking adjacent gates in the closed

position

The results indicated a arked reduction in both power

and efficiency when compared to the curves tor normal gate

operation However it was demonstrated that it was poae1bull

ble to ahitt the power and tfieiency curve ill relation to

turbine apeed lbis important feature will be diacussed

later

ihe main conclusion of the investigation was that conbull

trol by the conyent1onal wick t gates was auper1or to other

methode egtt control exercised at the gates the aelvebullbull

It would app$ar that the bebullt location tor flow conshy

trol would be in the draft tube since none of the objecbull

tiona prev1ously mentioned wou~d eziat there

As bas been stated previously the sole object or the

17

18

turbine is to produce power as etfic1ently as possible

The equation tor the power output of a turbine () Pbull 227)

PaWHe HP (4)55o bull bull Assuming the head 1a constant and a g te located in

the draft tube decreases bhe rate ot flow the power eu

only be increased if the etticiency increases

The ettective head Gn the turbine 1s conventionally

d r1ned as the difference between the auma ot the elevashy

tion head pressure head and velocity head at the entrance

to the turbine casing and the tailrace ($ Pbull 872)

lt ie recognized that the theoretical treatment ot

shock loss as given is highly approximate and serves only

to dictate certain trenda For example the area at xit

rom the wicket g tea CfUl be measuPed with some exactness

but there exists no guarantee that the wateP particles will

complet-ely fill the apace oz- will exit at the establiahed

g te angle The same can be said of the exit trom the

runner blades AssUIlptiona were implied which would indishy

cate that all water particles passing a given croea section

ampH traveling at the same velocity in the same direction

the e alone are autt1c1ent to show 11m1tationa in a theoretbull

1eal approach to the problem

Assume a turbine with ordinary wicket gates tor oonbull

trol compared gainst the same turbine with a gate in the

18

draft tttbe tor supplampment1ng control or the rate ot rlow

Let it also be assumed that the two turbines are opershy

ating at the same point It 1s desirable to predict relabull

tive performance of the two turbines 1 this point of

operation is such that edd7 s hook loss ot reasonable proshy

portions is present in the fir t turbine

~ tull erteot of the shock loss will be exper1 need

by- the fir t turbine

lhe second turbine will derive certain advantages 11

the gate in the draft tube is adjusted to reduce the tlov

1n the proper amount Since they vary a the square ot

the veloo1t7bull the lossabull in the aeroll case wiomiddotket gate

and runner passages will decx-ease aetet-r1ng to Figure 2 1

it can be seen that a decreased velocity v1 w-ill reduce the

eddy shock losa

The ent loss in the dJtaft tube of the second turbine

will be the sum ot the tr1ct1onal loss and the velocity

head at ex1t The velocity head dissipated will be greater

due to the closing action or the gate but the reduoed

t~ictional loss which ia a tunction ot the rate of tlow1

will partially balance this

It 1a entirely possible that the net reduction in

losses in the second turbine will lead to a greater ettibull

oiency and more power output than 4eYeloped by the first

turbine

19

In Figure 3 the plot ot power output against turbine

speed for Curv A~ represents the typical family of curvea

tor a reaction turbine Th b st sp ed is the locus ot

points connecting maximum eft1oiency at each gate opening

The operating speed is the coZUJtant turbine apeed which

passes through the point ot maximum efC1ciencr of the turbull

bine The plot of turbine efficiency against power output

for Curve A is also ahown

It the turbine with flow regulation in the dratt tube

oan demonstrate superior power and efficiency at part loads

the effect would be the same as a shifting or the power

curves toward the condition shown fop Curve B 11 Thisbull

illustrates th ultimate case of the uperpoait1on of best

and operating speeds It will be noted that the pet-form~

of the turbine ot Ourve Bu 1a better than that of CUrve

A at part loads because of ita ability to sustain a relabull

tively high etticienoy ovel a Wider range of power output

o Reguireaegts tort Test Velitication

It is desired to deterra1ne the effect on the turbine

performance b) the addition of a gate in the dratt tube

Th step in the teit will bet

(1 To determine the power output and efficiency ot

the turbine tor wicket gate settings above and below rated

conditione for a wide range ot speed

20

CURVEAbull

TURBINE SPSBD TURBID SPEKD

POIBR OOTPOl

Figure 3 - Turbine Performance Curves

21

22

(2 peat (l) with the gate installed in the drat

tube

(3) middot Converting middot all data to a constant head compare the

powere and effioiencies at the same wicket gate setting and

turbin speed tor the two cbullses

If the ddition or the gate indicates an improvement

in power output and efficiency and the powe~ curve shifts

to the right along the turbine apeed scale the advantage

ot draft tube con~ol of the flow will hav been demonshy

strated

Chapter IV

A E9J11pment

ih turbine used in this test is lJ 5 1nch Pelton

reaction turbine with a rated output ot 30 horsepower under

a head of 56 feet at a speed ot 720 reYolutiona per minute

Views of this turbine are hovn in Figures S and 6 The

turbine is installed on a concrete pad located over an open

channel in the Hydraulics Laboratory at Oregon State Colshy

lege The date of manufacture of this turbine was 1915

The water was delivered to the turbine from a sump

reservoir by two pumps operating 1n parallel Each pump 1a

an 8 inch Pelton double suction centrifugal pump witb a

rating of l$00 gallons per minute at a head ot 75 teet with

a speed ot 1175 revolutions per minute Tbe inlet tlange

ot tne turbine is $pprox1mately 18 feet above the center

line of the pump

A direct current generator was coupled to the turbine

to receive tne power d veloped as shown in Figures 4 and 7 The generator is a Spr gue Electrodynamometer rated at SS horsepower with a speed range of 7$0 to l$00 revolut1one

per minute The classification is type LO 26A 2)0 volta

Figure 5 - View of Test Turbine

Figure 6 ~ View of Test Turbine

and 149 amperes lbe generator ti ld was aepar tely

excited using direct current from a motor g n r tor ampt

(l$ p 4~8)

The power output of the generator waa dissipated in

the water rheostat (3 p 488-489) shown in Figures 9 and

10 The galvanized tank contain d water ot variable d pth

on an electrode ot cast iron m aauring 1bull x 1 x 1

In the initial installation of the turbine it was

intended that the power output should be measured with a

Prony brak bull For th purpoa68 or this teat it was decided

that the brake was too instable and the generator was

substituted The platform for raising the generator the

nee asary two teet for alignment was built out of available

material In this case heavy laminated wood blocks reiashy

torced with other timbers were used and bolted through the

concrete deck (11 Pbull 36-$7)

Due to the light concrete deck the lack ot mas in

the platform and the slight misalignment in the flexible

coupling ao e vibration waa encountered It seemed to

ncr aae linearly to a maximum at the speed of bout 750

revolutions per minute Above this speed no vibPation was

noticeable The vibration waa not se~ere and does not

appear to have materially affected the test results

26

B Intrumentat1on ~ eaeur1ng Devices

The pressure head at inlet to the turbine vaa meaave4

bymeane ot two )6 inch waterbullmeroury manometerbull connected

in series as shown in Figure 8

The terminal voltage ot the generator vas meaeured by

a laboratory voltDleter with a range to )00 yolta and callbull

brated to within 15 Yolta

The armature current bull and hence the line current was

measured by a laboratory ammeter with a range to 150 amperea

and callbrated to w1 thin o 7S amperes

Tae rate ot tlow was established by weight and time

meaeurementa The weighing ank has a capacity ot 121 000

poundsJ the weight belng indicated by Toledo direct reading

scales Timing was done with a hand atop watch with clivibull

aion ot 02 second

he ~ater level in the tailrace was dete~1ned by a

hook gauge lhie was read to the nearest 001 toot

The turbine and generator speeds were eaaured by a

hand tachometer The technique of almost cont1nuoua readbull

ings of the speed gave an error ot no more than 5 revolubull

tiona per minute

c Operational Procedure

Atter the water level in the aump was checked to

insure an adequate auppl7 the puapa were primed and

27

Figure 7 - Test Generator and Plattorm

Figure middot8- Instrument Board and Field Rheostat

28

started After venting they were valved for operation 1n

parallel

The motor generator set was started to supply the

field current and the circuit breaker was closed Water

wa added to the water rheostat to the level shown in

Figure 10 ~ field current wae minimized by cutting in

all the f ield resistance in the field rheostat of Figure 8

The l2 inch gate valve shown in Figures 5 and 6 waa

slowly opened and the turbine and generator brought up to

speed The 12 inch gat valve and turbine were vented and

the pumps were checked to insure neither had lost ita prime

lhe water rheostat offers very steady load 1f the

water level is essentially constant and the water temperabull

ture 1a fixed () p 488~89) In order to maintain this

constant temperature it was decided not to circulate the

water in the rheostat but rather to allow the water to

boil thua achieving the desired result A standing wave

was set up on the face ot the electrode by the boiling

action but a atable load was eatablished except at very

low water leYels where th11 agitation led to fluctuationa

in the line current

After putting the turbine and generator on the line

maximum power was dissipated in the rheostat by redueing

the turbine speed to between oSO and Soo revolutions per

minute Salt vas added to the rheoetat wat r to increasemiddot

29

Figure 9 - View of Water Rheostat

Figure 10 - View of Water Rheostat

Separate Field ExcitationFrom Motor-Generator set Compound Water-Mercury

---shy

re Manometer

I Q)

~ 0

~

Book Gauge

Open Channel

I

Slap Reservoir

Figure 11 - Wat~r Flow Diagram and Electrical Layout

31

waiting pe~iod ot perhaps an h~ followed

while the boiling point or the water wbulls reacbe4 During

this ti+ne the manometer was vented end eheoked electrical

measur1ng 1nstlUments were connected end the hook gauge was

adjusted tor elevation

It required about two- houtte tor the generator to reach

its normal operating tempe-ratu~e_ After the water in the

rheostat and generator had reached their operating temperabull

turea it was possible to begin the taking of data

The only vaPiable which was controlled wee the turbineshy

generator speed However the upper l1ut1t of safe line

current was slightly over 100 ampJilPampPes and the eireuit

breaker would open when the current reached lOS ~ere bull

Control was exercised by means ot regulating the water

level and salt 1n the water rheo tat and the res1stsnoe of

the tield rheost t~

The etfeet ot each type ot regulation on the three

variables is shown below

Volta Aaperebull Speed

Inc Dec Inc Dee~ Inc Dec

Wa~e1 Level Inc Dec~ X

X X X X

X

Salt Concentration

Inc Dec X

X X X X

X

field Resistance

Inc Dec

X X

X X

X X

32

Jlot all methods gave the ame amount ot change in a

given variable and a period of experiment and trial led to

the following scheme starting the rune with the lowest

turbine speed the water level was high with a high amount

ot salt and the field resistance was cut completely out

Aa it became necessary to increase the speed tor each

aucceasive run either cutting in t he field resistance

decreasing the salt concentration or lowering the Vater

level would produce the desired result However decreasbull

1ng the salt concentration had to be done Without a net

gain in water which led to a tluahing procedure that was

not particularly good because cold water was introduced

which required time to heat to the boiling point Cutting

1n additional field resistance was a good method but th1a

increased the amperage possibly to the point of opening

the circuit breaker Lowering the water level was aatiashy

factol1 until the level got too low causing the current

fluctuation previously mentioned Actually it turned out

that a combination of lowering the water level and cutting

field resistance in would carry the speed from ita minimum

to 1ts maximum value it the proper choice were made each

time the speed waa to be changed At the conclusion of

each aet of runs at a high speed the water level would be

low and the field resistance high

33

TURBINE

PAD AND DECK

TAILRACE

WATER SURFACamp

CONCRETE

DRAFT TU1B INSERTS

7 5( DRAFr TUBE

FLltJI ARIA

5~ DRAFT TUBE

FLOI ARSA

Figure 12 - Sketch of Draft Tube and Test Inserts

34

Figure 13 - View of Draft Tube Insert

Figure 14 - View of Draft Tube Insert

D c __ ~s_middot hedu_le of

A number was assigned to each run The fi~st number

applies to the draft tube tlow areas

1 bull 100~ flow area or 0~ oonatriction

2 - 7S tlow area or 2$ conatr1ct1on

3 SoC flow area or so~ constriction

The second number refers to the wicket gate openings

9 over gate opening

6 bull intermediate gate opening

4 bull one h lt gate opening

The third number 14entif1ea the location of the particular

1Wl in a set ot rona made at a given dratt tube tlow area

and wicket gate opening

fnua run number 1bull4bull10 would identity this as the

tenth run ot a set made at halt gate with 75 ot the draft

tube t1ow area

Rune w re made tor a g1yen dratt tube condition

Firat tor tull 41-aft tube flow area seta ot rune were

made for the overgate halt gate and intermediate gate

conditione An insert was placed in t he draft tube and

rune based on the same gate conditions were made tor the

7S~ draft tube flow area case The insert was then changed

to allow only $~ draft tube flow area

The inserts are sketched 1n Figure 12 and photographed

ln Flgurea 13 and 14 They oonaisted of circula~ segments

36

or l2 ineh plywood mount 4 on wooden legs 10 inches high

The 1nse7te were placed in position and secured by th use

ot a-clamps on the legs and the outside ot the bottom of

the draft tube The obvious disadvantage to this method

waa the neoeasity tor draining the water from the tailrace

tor a change ot 1naert The advantage vas of course the

simplicity ot design and construction

Chapter V

DATA-A Original Data

The normal data-taking crew consisted or two men

Assuming adjustments having been made to secure a certain

turbine speed (aee section on Operational Procedure) one

man would take semi-continuous speed readings with the hand

tachometer until a state or rotational equilibrium was

reached This could be only a period or two minutes up to

ten or tifteen minutes As soon as steady speed was

assured the data taking would begin The second man went

to the weighing tank Where a minimum ot three weighingamp

were made The requirement was to get three consecutive

readings such that the ditterence between tbe smallest and

largest time did not exceed 04 seconds The time to

collect a given weight ot water was then assumed to be the

arithmetic average of the three times He then went to the

hook gauge determined the hook elevation and then

recorded the data on the data sheets The first man meanshy

while had taken readings of the line voltage line current

and manometers and checked the turbine speed by multiple

readings During the length of the run all values were

38

checked to determine mean values for recording

The minimum length of one run was about five minutes

If one or more measure ants tended to drift during the run

all values wer discarded and a new run began as soon aa

qu111br1um was stabl1shedo

B -0-al_e_u_l_a_t--d Data

The h d on the tu~bine 1 defined by

($)

The maxtmwm velocity V4 was equal to about o8 tampet per

secon4 which makes it a negligible quantity when converted

into velocity head

An engineerbulla level was used to deterine the d1ffePshy

ence 1n elevation between the compound water-mercury manoshy

meter and the hook gauge Using this value the equation

for turbine bead becomes

where z4 is the hook gauge reading

The rate of flow 1 cent

w weight or water collected average time to collect

The inlet velocity v1 vas calculated by dividing the

weight rate or flow by the specific weight of water and the

)9

area ot ~e inlet pipe This was equivalent to dividing

the weight rate of flow by 490 Then the power input to the turbine is equal to

WHpin rri

10 (6)

Also

(P ~ut) Turbine

(P out) + Generator

(P lost) Generator

The power output of the generator is simplJ the

produot ot the terminal voltage and the armature (line)

curPent The power lost in the generator can be subdivided

into copper losses and stray power losses lo evaluate

these cunes based on losses of an identical generator

11leampsured by the Department ot Mechanical Engineering were

used The loss curves are reppoduced in part in Figures

15 and 16

Determination ot generator losses proceeds as tollowau

(1) From Figure 15 detem1ne the vo1tage drop in the

armature circuit using the temperatures of 1220 F and the

meaaured current

(2) The induced voltage is t~e sum of the terminal

voltage and the voltage drop 1n the armature circuit

() Entering the induced voltage and the turbine speed

into Figure 16 the stray power loss can be determined

(4) The copper lose can be evaluated from Figure 1$

using the measured current and the temperatlll-e of 1220 P

40

25 ~------~--------~--------~------~

U) -U) - 20

f-4 ~

-~ -gt 0

0

VOLTAGE DROP

~ - i -

- bullbullbull bull - -middot-middot -+ ~- + -t--+ ~ - ~ middotbull ~-~ middott- -+----- _ -4 middotmiddot- --~-+-t---r~~ ~--+t-t- - ---t-c-++~-ulf--

0 50 75 100

Figure 15 - Curves of Generator Voltage Drop and Copper Loss

41

1200

1000

800

600

800

0

0

~-

middot--~ 1shy --1 + bull l

100

I -

150 200

IIDOOED VOLTAGB (VOLTS)

Figure 16 - Curves of Generator Stray Power Loss

_ j

-bullshy -L---- shy middot -shy

250

- r

42

(5) The generator los os equal the sum of the eopp r

loss and stray power loss

~e efficiency or the turbine is taken as

etticiency u e =P out (8)Pin

~ample pound Determ1n1gg turbine Power Output

The following data are taken trom that ot Run 1-9-1

Line voltage 1040 volts Line current 870 amperesSpeed 355 revolutions per minute

The induced voltage 1a determined as follows

Line voltage 1040

Voltage drop 90 using Figure 15 with line current of 870 amperes and temperature ot 122 degrees)

Induced Toltage 1130 volta

The power output of the turbine is determined as follows

Generator output 90$0 (line voltage z line current)

Oopper loss 7 (using Figure 15 with line current of 870 amperes and temperatUe or 122 degrees)

Stray power lose 470 (using Figure 16 with speed ot 355 revolutions per miDUte and induced voltage or 1130 volts)

Turbine power output 9527 vatta

or turbine power output 1s 12z2 horsepower

43

The conversion of the calculated data to a constant

head is based on the conventional assumption of constant

efficiency regardless of turbine head For a constant head

ot 81 teet a purely arbitrary figure the tollowing relashy

tionships are ass1lJiled to be true

I ____L (9) (i)l72

(10)

For these two values the specific a peed may be combull

putedt

N t Jt VPt (11)8 243

Chapter VI

~RESULTS

A -Pr_e_ae_n_t_a_t_t_o~n g Reaultbull

Graphical presentation ot the results ot this te1t

are given as follows

Figure 17 -Turbine characteristics with 100~ dratt

tuba 1low area

Figure 18 - Turbine characteristics with 7S dratt

tube tlow area

Figure 19 bull Comparison ot power and etticiency at

over gate conditions between 100 and

75~ draft tube flow area

Figure 20 bull COZQparison of power and ettic1ency at

halt gate conditions between 100~ and

7S~ draft tube flow area

Figure 21 bull Comparison of power and etticiency at

over gate condition between 100~ and

So dratt tube tlow area

Figure 22 - Comparison in variation ot apec1t1c

speed between 100 and 75~ dratt tube

tlow area

50

45

20

-bull - 1--shy40

bull J-~ 30

~ ex

~ 20

~~ ~ -)q

I

~ - _

- -

10~ OF DRAFT TUBE FL(Jif AREA

CONSTANT HEAD OF 8l FEST10

POIER OUTPUT EFFICIENCY SPECIFIC SPEED

0 ~--------------_--------~------~------~ 400 600 800 1000 1200 1400

TURBINE SPEED (RPM)

Figure 17 - Turbine Char~cteristics with 100 Draft Tube Flow Area

50

46

-bulllle

~ 7 ~ OF DRAFt TUBE FLOW AREA

0 -~~-rl C05STAMT BEAD OF 81 mET 1J~

POIER OOTPUT ---+- ---o ~_H EFFICIDCY ~ I shy

bull ql SPECIFIC SPEKD - ~ -

bull ~ J 10 L rmiddotr- r- -

bullz- I

~~ 30 ~~--~----~~-

20 ~ ~ middot-shy

26

~~ 25

~0 ~r-----i (

Tbull -bullshy

400 600 800 1000 1200 1400

TURBINE SPEED (R PK )

Figure 18 -Turbine Characteristics with 75 Draft Tube Flow Area

47

EFFICIENCY 60

1-----shy

-~ 50~--~--~~-~middot middot middot middot r~-~----~~~~---4~-r~-~~gtt

II

POWER~ J ~ bull bull

u I

sH

40~------+-------+---- -~~--~~-~~~~

~----~rl 1 bull

I

I

0~--------------~------_------~--------

~ -OVER GATE CONDITION

COIJSTANT HEAD OF 81 FEET

0 o 10~ DRAFt TUBE

_-- _ 7~ DRAFT TUBamp FLON AREA II

10_~-----+--------r-------r----~~

400 600 800 1000 1200 1400

TURBINE SPEED (RPM)

Figure 19 middot - Comparison between 75 and 100 Draft Tube Flow Areas of Power and Efficiency at Over Gate Conshydition

48

t

bull --4 r ~- ~ middot~

70 1-----------+-~~~~~+middot ~ ~~ middot middot -~~--~~--------~~----~-+1

-~-

Atbull bull

lla-

60

amp0

40

20

10

oampOO

t _ - - ~-+- - -~-

l2 GATB COJIDITIOJJ

COJISTABT HJW) OF 81 JBET

o 0 lOQ( DRAFl TUB8 FLOI AREA

e-- - e 75 DRAFT TUBE FLOW AREA

800 1000

- r-

~

TURBIbull SPBIID (RPII)

Figure 20 - Comparison between 75 and 100 Draft Tube Flow Areas of Power and Efficiency at Half Gate Conshydition

49

60

50

-40

bull 30

IIQbull

20

10

0

400

- t - ~

EFFICIENCY

_J bull - bull bull

~ r r middot t -+ shy L -t -

OVER GAD COliDITIOI

CONSTABT BEAD OF 8l FBB

o o 10~ DRAFt TUBE FLOI ADA middot--- 5~ DRAF TUBE FLQPi AREA

600 800 1000 1200

Figure 21 -Comparison between 50~ and 100~ Draft Tube Flow Areas of Power and Efficiency at Ove~ Gate Conshydition

50

25

20

15

10

0

Figure 22

~- T -4 -t- -l --~-

t-~ I

middot --~- t ~---- _ __ _ + --

----~- --r-- --

~-=J-~-=-~ -==~ _ ~- -- ---f---1 - shy

CONSTANT HEAD OF 81 FEBT

o--o 1~ DRAFT TUBE FLltll AREA

75C DRMT TUBK FLCIJ AREAmiddot--middot-middot 600 800 1000

TURBINE SPEED (RPK)

Comparison of Specific Speeds for 75 and 100 Draft Tube Flow Areas

51

B Discussion 2 Result

Consideration of Figures 17 and 18 indicates the

overall eftioi ncy pattern or hill is significantly or

rounded for the 7$~ flow area than for the 100~ flow area

bia implies a greateP efficiency is possible at speeds

leas than or greater than design speed with an insert in

the draft tube However the muilDum efficiency is lemiddotas

Direct comparison at over gate conditions is made in

Figure 19 ~e same general trend is noted tor both the

etticiency and power curves for the 7$~ flow area case

The eurves show higher values at overspeed than do the

correaponding cWvea for the 100 flow area case It ia

not clear whether the curves have been shifted by the dratt

tube constriction or whether the curves simply bulge past

the normal curves at both overspeed and underspeed condishy

tions The power curves apparently peak near the aeme

point bullalthough maximum power is still obtained with the

normal draft tube area

For the comparison at halt gate operation shown in

Figure 20 a general improvement has apparently been made

by restriction of the draft tube flow area At every speed

the etticienoy and the power is greater for the restricted

tlow case The two ett1o1ency curves and two power curvea

are practically parallel throughout the speed range ot

teat

As the flou aroa i e decreased still farther a s1gn1

ticant change appears Reterr1ng to Figllle 211 tor the $0

flow area curves it a obvious that exit losses have

become excessive at the overgate condition because the

efficiency and power are everywhere leas than tor the case

of normal draf t tube area

Earlier it was pointed out t hat 1t the r esult s 1nd1bull

eated an increase in both power and ef tieiency- t hen it

could be assumed tha t the additional los s i ntroduced with

the draft tube insert is less than the diminished losses

due to leas shock losa and water passage losses For the

places where both the efficiency and power have been

increased we can assume that the insert has improved turshy

bine performance

For the places where the power haa been decreased

nothing can be said as to the elimination of ampbock loss

because the new lose present with the drat tube insert has

overshadowed any gains in eftecti Ve head upatJ-eam of the

insert

Near the peak of the efficiency hill howeve~ it may

be pointed out t hat shock loaa ie a minimum with a normal

draft tube and the insert merely adds an additional loss

with the resultant decrease in maximum efficiency tor the

7$~ flow area case

Perhaps the most s1gn1ticant set of eurves is shown aa

53

Figure 22 In this graph values of specific speed tor the

75 and 100~ flow area cases for both over gate and one

halt gate openings are plotted against turbine speed At

every speed and both gate openings the value ot specific

speed for th 75~ flow area case is greater than that for

the 100 t1ow area ease

Since the head is a constant for both situations this

may be interpreted in either of two ways trom equation

(11)

(1) For the same turbine apeed restriction of the

draft tube t1ow area resulted in greater turbine power

(2) For the same power amputput the turbine with 75~

draft tube flow area operated at a greater speed than did

the one with 100 flow area

Since the required diameter of a turbine varies

inversely with the speed the second interpretation could

be stated such that a smaller turbine could be used to

develop the same power output

Whether viewed trom the aspect of increased power

greater speed or reduced size the performance of the turshy

bine with reduced draft tube flow area is superior to that

with the nolmal flow are in the draft tube

The curve of specmiddotific speed versus turbine speed for

the so draft tube flow area case at over gate cond1t1ona

was not included in Figure 22 This curve lies below that

for the 100~ flow area c se at all speeds

In elaboration ot the second interpretation of Figure

22 attention is directed to the relative magnitudes ot

increased apee1f1c speed tor the two gate openings Assumbull

ing that the increase in specific speed implies a shift ot

the power curve to the right along the turbine speed scale

the power curve would be shifted more tor tbe halt gate

opening than tor the over gate opening

It thia trend could be extrapolated to the other gate

openings the tendency can be seen tor the line ot beat

speed to rotate toward the line of the operating speed as

illustrated in FigtU-e ) The advantage of this has already

been discussed

This particular turbine has a low specific speed tor a

reaction turbine Aa the rated value of apecitic apeed tor

reaction turbines increases the line ot beat speed departs

even more radically from the line of operating bullpeed It a

test similar to this were conducted on a reaction turbine

ot gleater specific speed it is pJobable t hat the rotation

ot the line of beat apeed would become more p~onounced

The scheme used in th1a teat had two obvious dr wbull

backs The first was the decision to leave all the wicket

gamiddottes installed tor all conditions ot the draft tube

These gates predominated in control of the tlow The

inserts added to the draft tube merely acted as auxiliary

55

contrGla

The aecond drawback was the choice or device to place

in the draft tube The reasons foll selection of this type

of device have been previously mentioned It is to be

anticipated that adaptation ot dratt tube flow control

would result 1n a better device for an actual turbine

installation Such apparatus might take the form of a

pneumatic bladder or a h7drau11oally operated variable

venturi section in the draft tube It is conceivable that

the gate as used in this test might be adapted also

Chapter VII

OONCLtJSIOfS

From the results of this test the following eonolubull

e1ona aa to the effect ot a variable draft tube flow area

on the performance or a r action turbine may be drawn

(1) The effect ot a variable draft tube tlow area 1a

generally favorable upon the operat1Gn ot a reaction turbull

bine because or the tendency tor the line or beat speed to

rotate toward the line ot operation This resulte in

better performance of the turbine at partbullloads

(2) he etf1o1ency eh111 tor the turbine beeomaa JDore

tlat at the top leading to a smaller max1JilWD effic1enc7

but e reater etticieney at other pointe of operation with

the insertion ot an auxiliary control ror the rate ot tlov

in the draft tube

(3) The power output of the turbine will increase at

over speed over gate conditione as well a at part gate

conditions with the proper amount or draft tube eonatr1cbull

tion or flow

(4) It is possible to eliminate at least partially

eddy type shock loss by tho introduction ot flow control

in the draft tube

BIBLIOGRAPBl

1 Addison Herbert A treatise on applied h-draul1cs New York Wiley 1954 724 Pbull

2 Allen o M and I A Winter middot Co111parative testa on experimental draft tubes Tranaact1ons ot the American ociety ot Civil Engineers 87t893bull970 1924

3 Barrows a E Water power engineering 3d ed ew York McGraw-Bill 1943 791 Pbull

Bovet G A Modern trenda in hydraulic turbine design4middot in Europe Tranaactions of the American Society ot Mechanical Engineera 75975bull993 1953bull

s Oreager William P and Joel D Justin Hydroelectrichandbook 2d ed New York Wiley 19$0 1151 Pbull

6 Daily Jamea w Hydraulic machinery Int Hunter Rouses Engineering hydraulics Hew York Wiley 19$0 p 8$8bull99

Daughertybull Robert L Bydraulie turbines ew Yorkbull7middot MoGrav-Hlll 1920 281 Pbull

8 Daugherty Robert L Inveat1gat1on of tne performance ot a reaction turbine ~anaactiona or the American Society ot Civil Engineers 7811270bull1304 1915

9 Davie L M Model and prototype testa Int Trend in hydraulle turbine practice symposium lranaactions ot the American Society ot Civil Engineers 1o63S3middot368 1941

lfJ Doland James J Hydro power engineering Hew Yorkbull Ronald 1954 209 Pbull

11 Gandy Theodore s and Elmer c Schacht Direct curshyrent motor and generator troubles operation and repair New York McGraw-Bill 1911 293 Pbull

12 Gibaon Arnold H Hydraulics and ita applications5th ed London Constable 1952 813 Pbull

58

13 Button s P Component loases in Kaplan turbinebull and The prediction of efficiency from model tests Probull coedings of the Institution or Mechanical Engineers168743-762 1954

14 Knapp R T~ Oavit t1on mechanics and its relation to the d sign or hydraulic equip ent Proceedings or tne Institution ot Mechanical Engineers 166150bull16) 1952

15 Langsdorf Alexander s Principles of direct curHnt mach1nee 5th ed New York r~cGrawbullH1ll 1940 746 Pbull

16 Lsrner Chester w Characteristica of modern hydraubull lie turbines Trans e~ions of the ~~erican Society ot Civil Engineers 66306-386 1910

17 Linsley Ray K Jr and Jobulleph B Franzin1 Eleshyments of hydraulic enginebullring New York McGrawshyBill 19$5 $82 Pbull

18 Mead Daniel w Hydraulic machinery llev York McGraw-Hill 1933 396 Pbull

19 ead Daniel w Water power engineering New York McGrawbullRill 191S 843 Pbull

20 Mockmore Charles A Part gate operation at water turbines Corvallis Oregon State College Department ot Civil Engineering 1933 11 numb leaves (Unpubshylshed typescript)

21 Mockmore Oharles A Flow characteristics in elbow dratt tubes Transactions of the Amez-ican Society ot Civil Engineers 103402middot464bull 1938

22 Moody L F Hydraulic machinery In c v Davis Handbook ot applied hydraulics New York McGrawshyHlll 1942 1082 Pbull

2) Ptau At-nold Hydrbullulie turbine handbook ld ed Milwaukee AllisbullOhalmers ManufactUIing Company 1948 70 Pbull

RheingalUI w J Recent developments in Francis turshybines Mechanical Engineering 74189-196 1952

25 Russell George E Hydraulica 5th ed New York Henry Holt 1942 466 Pbull

26 Safford A and E P- Hamilton American mixed tlow turbine and ita setting Tranampactions or the Amerieal Society of Civil Engineers 851237bull1)56 1922

27 bull Spannhake W1lhe1Dh Problems or modern pump and tur b1ne design Transactions of the American Society of Mechanical Engineers 56e22$-248 1934bull

28 Sutherlandraquo R A Better ethod or representing and middot tudying water turbine performance ~ansaetions ot thmiddote American Society of Mechanical Engineers 68t675bull 686 1946

29 Teats ot five models or draft tubes tor turbines Engineering News-Record Pbull 182-184 Aug 2 1923

30 White w M American hydztaulic turbines Mechanical Engineering S2t390bull39S 1930bull

31 White w M lhe hydraucGne rega1ner1 its developmentand appl1eat1ons 1n hydroelectric plants Meohanlobulll Engineering 43t37Sbull380 1921 middot

32 Winter I A Economic principlebull in designbull Int Trend in hydraulic urbin practice bull a ampoeiumTranaaot1ona ot the American Society ot Civil Engineerslo6332bull3S2 1941

33 Wiel1cenua G F Fluid mechan1ca or turbo-machineryNev York McGraw-Hill 1947 613 Pbull

APPENDICES

c

Appendix A

NOATIOB

A Angle between the absolute velocity vector and the tangent to the rwmer Subscripts 1 and 2 refel to entrance and exit ot the runner blade

B Angle between the relative 1elooity vector and the tangent to the rwmer Subscripta 1 and 2 refer to entrance and ezit or the runner blade

Angle between the tangent to the runner blade tip and the tangent to the runnel- Subscripts 1 and 2 reter to entrance and exit of the rt1rmer bladebull

Blade angle-gate opening conetant defined by equation (1)

e 09erall efficiency

g Gravitational acceleration assumed constant at 322 teet per second per second bull

H Turbine head detined by equation ($)

m Exit loss coeft1e1ent

Turbine speed expressed in revolutions per minute

Turbine speed under a constant head of 81 teet

specitic apeed of the turbine under a constant head ot 81 teet

p Power output in horsepower ot the tvbine

Power output of the turbine Ulder a constant head ot Sl teet

Pl- Pressure head at entrance to the tUlb1new

l1 Peripheral velocity ot the runneP Subacr1pta 1 and 2 refer to entrance and exit ot the JUnllampr blade

62

v Relative velocity reaulting trom the combination ot the absolute water velocity V and the runner periphshyeral velocity u Subscripts 1 and 2 refer to entrance and exit ot the runner blade

v] Relative velocity vector necessary to produce a tanbull gential entry into the runner blades

V Absolute water velocity Subscripts l and 2 refer to entrano and exit ot the runner blade

v2 Velocity head Subscripts 1 and 4 reter to the ~8 entrance to the turbine and the tail~ace wate~

w Unit weight ot water assumed constant at 624 pounda per cubic toot

V Weight rate ot flow in pounds per aeooncl

XX Velocity component ot ahook See Figule 2

Z Elevation head Subscripts 1 and 4 reter to entrance to the turbine and the taibace water surfacebull

Appendix B ORIGINAL DATA-Run

lfwnber

0-4-1 0-4-2 0-4-3 o-4-4 o-4-S o-4-6 0-4-7 0-4-8 0-4-9o-4-lo o-4-11 o-4-12 0-4-13

o-6-1 o-6-2 06-3 o-6-4o-6middotS o-6-6 o-6-7 o-6-8 0-6-9 o--6-lo o-6-11

Speed

rmiddot2middotbullmiddot(1)

336 38$ 451 S$9 620 669 6lt)$ 120 787 860 932

102imiddot109 bull

352 355 443middot 543middot 620 654AJs32

911 1001 1111

~essure Head rt (2)

410 410 416 426 431 43-7 439 44-9 452 467 482 soo $1 bull $

350 351 35middot7 )66 37-9 37-9 392 41 bull 3 43middot3 460 489

Elevation Bead

fjj $7 $7 $7 $7 $7 $7 51 57 5-15858 $8 58 56 56 $6565656 51 575As5a

Velocit Head

flj 07 07 07 06 06 06 06 os 05 os0404 03

09 09 oa o8 o8 os 07 07 06 o~o

Total Head rt ($)

47middot4 4A44 o 489 49-4 soo $02 $11 $14 $29 5imiddot45 2 576

41 bull $ 416 421 430 44middot3 44middot3 456 47-7 496 523551

Plow

lbtjec

326 324middot317 311 306 30029middot28 middotmiddot middot 386 275middot260 240 218

359 36~35 bull 349 345middot 339 330 318 300 273 240

Line Potential

vyqjbull 1060 1220 ~-0o 1920 2150 2000 2$60 2000 1940 18)015io11 o

1000 1100 139bull5 1760 1925 16$0 1620 1610 1540 1330 870

Line Current

amlscs 960 900 830 740 730655 70bull 0 530 660 600 5imiddot54 6 )60

982 930 860 780 ~3-545

79-5 74-5 670 560 370

P

Appendix B ORIGINAL DATA (Continued)

Run Number

Speed

Pbulltmiddotbullmiddot )

leasure Head ft(2

Elevation Head tt(J)

Velocity He-dfmiddotj

Total Bead tt($

Flow

lbstsec( )

Line Potential vo~ta( )

Line Current

amjs (sect

0bulllt)-1 0-9-2

3ll6 398

28o ~~1

$6 56

1o 10

346 347

390 365

1ooo 1190

aao 835

0-9-3 0-9-4 o-9-S

472 565 632

292 305 312

$6 s6 56

10 o9 o9

)$8 J7~o 37~7

381376 37o

1)6614oo 141o

820 ass ass o-9-6 0-9-7 0-9-8 o-9-9 0middot9-10

680 120 762 844 920

)24337346 366 390

56 $6 56 57 $7

09 os o8 oa 07

)89401 410 431454

367~ 357348 34o 322

1400 1J6o l36o 1310 1170

843 820 7957So 67~0

0-9-ll 0-912

1001 1100

41 bull 7 45-3

s 7 6~0

06 os 480 $18

299 268

980 65$

560 36~5

1-4-1 1-4-21-4-l1-4shy1-4-5 1-4-6 l-4-7 1 4-8 1-4-9 1-4-10 1middot4-ll 1-4bull12

354middot452 562 62q 674shy102 752 760- 863 932

1022 1100-

)82389 4014oa 416 41--7 423 428 44-2 45-7 486 49-2

51S757 51 5-7 5middot15zs sa $8 58 59

07 07 06 06 06 06 06 os o bull o 04 o J

446 45-)46middot4 471 ti7-9480 q86 491505 $19 548 55-4

)28 320 311 306 300 295 291 286 269 2582iimiddot21 bull

1080 14Lo 1550 153-5 1470 141-0 1385 1310 1310 1230 1120 855

970855 875 91-0 94~0 975 966 995 860 77-S 610 4fo

0 ~

Appendix B ORIGINAL DATA (Contirmed)-Run Speed Pressure Elevation Velocity Total Flow Line Line

Number Head Head Head had Potential Current rtjjmbull t~ bttec vyfs am~a12) ( ) ti fli 8

1-6-l $6 33$ $6 0bull9 400 364 1100 93 0 1-6-2 41 34laquo2 $6 oa 406 JS7middot iios a5s l-6-3 500 3~0 5bull6 os 356 1 1 o aos 41middot~1-6~4 35bull4 5-6 oa 41middot 352 16~0 82 0 5~1-6-5 5 bull 36_2 Sbull6 08 42bull6 349middot 161 ~ 0 86~0 1-6-6 622 366 $6 oe 43bull0 345middot 158 0 88~$ 16-A 649bull 37bull1 56 os 43-S 342middot 1570 895 1~- 386 57 07 46-0 192 ) 125A44 333middot 1-6-9 3) 404 5middot1 07 468 317 1620 675 1610 911 42-4 5-7 o6 48-7 298 168 0 61 0 1-6-11 999 451 56 os Sl ll 276 ~2-0 530 1-612 1115 485 58 04 54middot7 238 90 )3 0

1middot9-l 355 279 56 10 )45 385 1040 870 1-9-2 399 28J $6 10 )49 38$ 1140 86 5 l-9-3 ~ ao 291 56 ~0 35middot1 J8J_ JJ6o 815 1bull9-4 579 303 56 09 )68 375middot J4JO 830 l-9bullS 40- 313 )6 09 31middot8 370- 1460 82~0 1-9bull6 679 2) 56 09 3 bull8 364middot 1670 710 l-9-7 682 319 56 o9 384 ) 62 1460 79 5 l-9-8 724 33middot5 56 o8 399 3$6 bull 1480 76 -5 1-9-9 762 34middot3 $6 0 bull 8 407 )48 14910 13middotS 1-9-10 833middot )60 5middot7 os 42$ 339 144$ 686 1-9-ll 926 39middot1 5-7 07 455 318 1290 600 1-9-12 1000 41middot3 0-6 476 298 1115 510$ ~ 1middot9-13 1105 452 s o4 $14 2$6 710 )10

~

Appendix Bt ORIGDIAL J (Continued)

Run Speed Pressure Elevation Velocity Total Plow Line Line Number Head ltead Head jlamp$d P()ten~ibulll Current

r~~~m ft ft lbs~seo voltattj rgj twimiddot t 1 t2gt lt3 ou t ( rt

2-9-1 384 289 S 6 10 35 5 1400 1170 810 2-9-2 443middot 29$ $6 ltimiddot9 360 379middot 11(0 87$ 2-9-J 536 30bull 3 sc 09 )68 374middot 1)40 84 bull) 2-9-4 571 306 $6 09 3~1 372 120bull 0 955 2-9-5 623 316 S6 09 J l )6S UJSo 77$ 2bull9-6 669 327 S6 09 )92 )61 1240 905 2-9bull7 712 )39 56 os 40-3 351 12(0 86 bull0 2-9-8 ~5$~ J48 56 oa 412 348 1290 81 bull ) 2-9-9 04 )63 56 oa 42-7 339 12ltJO 76$ 2middotmiddot9-10 8$2 376 5middot1 07 440 33~- ~ o 710 2-9-11 955 394 5-1 o6 457 300 1100 506 2middot9-12 1000 421 $7 06 48middoti 295 1020 $18 2-9bull13 110~ 463 56 05 $2 267 620 3~0

oshy0

Appendix Gt CALCULATED DAgA

Turbine Run Generator Generator Turbine Turbine Efficiency Turbine Turbine Specit1c

Number OutputKWlt21

Loa~Jes KWlol

Outut K bull (H)

Input RP 12)

middot Percentlt13gt

Speed r~Jmiddot(

0ltput HP ~1

Speed r-m

( 6) middot

o-4-1 0middot4-2 0-4-3 0-4-4 0-4-5 0-4-6 O-qmiddot7o-4-8o-4-9 0-4bull10 0-4-11 o-4-12

1018 1o9a 1220 1)62J40214oa1J4oo 1357 1320 1164 997 718

046 o59 071 092 096 1071oo 134 104 100 109 107

14261sso 17)01948 2008 20322011 1999 19 09 1708 14-84 11o6

281279 27-7 276 215 273271 268 268 26h 258 24-5

soa 555 62$ 705 7)1145 742 74-6714645 51s 45-1

440 sos 585 720 195 sso sao 9$$ 985

1065 1135middot 1230

318 357 319 416 422 419412 39middot9 378 324 260 191

102 12bull4 148 191 21bull 3 22o 233 249 24924middot9 238 221

0-4middot13 418 104 699 228 306 1300 117 18)

o-6-1 982 045 1376 271 $08 496 376 124 o-6-2 o-6-3 G-6-4o-6-5 0-6-6

1023 1200 13 73 J415 139h

051 0middot66 oaa ()bull 96 088

14-39 1696 1958 2026 1986

276 27middot4 273 278 274

$20 61 8 717 7)0726

q95615745 8)5685

390 ll5middot3 sos soo 490

127 170 218 243 2$$

o-6-7 o-6-8 o-6-9o-6-lo

1288 1199 1032 7-45

o9o 094 09$ 096

1846 1733 1511 1128

274 276 271 260

67S 629559 43middot4

980 1085 1165 1245shy

436 )83316 21bull 7

266 276 270 239

0-6-11 322 1oo 566 2141 2JS 1350 101 177 0 --4

Appendix C CALCULATED DAlA ( Continued)-Run

Number Generator Generator

Out2ut Losaes xw LW- 12gt (lO)

Turbine Out2ut

ltPlJ

Turbine Inat lfP Jig)

Etpound1e1ency

PireentDl

Turbine Sed x-~m( 1

Turbine OutEut RPJl)

Turbine Specific

SeeedrIbullntbull

( 6)

o-9middot1 0-9-2 0-9-3 o-lt)-4 09-$ 0bull9-6 0-9-7 0-9-8 0-9-9 0-9-10 o-9-11 0-9-12

aao 994

111$ 1197 1206 1180 11)21081 982 784 5-49 2)9

0middot45oss o6$ 070 07$ 0-77 (l77 or~ o s06o 8 096

123~ 1402 1$80 1698 17bulllS 168$ 16bull18 ~middot5430 1151 a~J4 9

24middotgt24middot3248 25~25 260 260 259 267 266 26middot1 2S2

sos 577 63-7 671 676 650 621 60036J4

327 178

$) 610AlO 3$

92S 980

102$ 1070 1157middot 1230 1300 137Smiddot

44middot4 soo 523 ssomiddot 540so6 46-5 432 368 274 18~8

J46 176 21-1 255 2802s_A 28 289 288 265 231 168

1-4-1 1-4middot2 1-4-3 1-4-4 1-4-5 1-4-6 1-4-7 1-J-8 1-4~9 1-4-10 1-4-11 1-4-12

10bull48 1231 13-S6 1397 1)821375 1))8 1303 1127 953 683) 51

048 067 o7A07 0 bull79 oa1 oss o bullao osa 0lt)0 096 099

J468 1740 1921 1978 1958 19$1 1911 lSSi162 1)98 1045

603

266 264 262 262 261 2512$7 2$6 24middot7 24-3 233 217

551 660 13middot3155 75-6 7~-97 middot4 72$ 67 51middotJ 44middot9 21middot1

475 605 A4220

875middot 910 970_

1000 1090bull 1166 1243 1330

5816

44middot444middot5 430 427 412 392 329 273 188 l0-7

117 101 204 22$ 2)7245 2562sa 257251 222 179

a-C))

Appendix Ct CALCULATED -DATA ( Ocntinued)

1-6middot1 1023 o$2 14-41 26S 505 41~6 26~

54middot5 13middot3l-6-2 1201 067 1boo 625 47-9 17shy~middot41-6bull3 1296 oA9 1 middot43 26 9 700 so5 20bull 4 l-6-4 l3j5 o 0 19~09 268 71bull3 A5o 514 222 1-6-5 1) 5 o81 19(gt4 271 725 51-5 238 l-66 1398 081 198) 27-0 736 8 S13 252~-middot l-6j 1405 083 199i 211 733 885 $middot06 2$9 l-6 13middot9~ 103 2amp 0 279 71 8 985~ 467 ~-69 1228 1 bull 02 17-SS 270 661 109$ 407 ~3~ l-6bull10 1025 100 lSll 26i 573 1175middot 27~S32middot~l-ampu 153 1-00 llft3 26 444 1270 22 24bull8 1bull6-12 294 100 52a 231 22 3 1360 95 172

1-9bull1 904 048 1275 2J4Z $28 S4$ 459 1$2 1-92 98$ oss 13-92 24middot4 57-0 6JO 49bull1 176 1-9middot3 1110 066 1$76 24middot9 63middot4 I2o 536 21-7 l--9-4 1187 072 1685 251 66$ 5 $$ bull 0 261 1middot9-5 llltJ7 1710 25middot4 67-3 93$ 536 28~20-671middot9-6 1186 o 8 1708 25-7 67) 980 $15 2691-9- 1161 oBo 1660 2$middot3 6$6 990 508 29-1 l~- ll-32 oB) 16sect0 2$8 632 1030 471 291 1-9bull9 109$ oa5 2$7 614 1075 29S~middot 0 4imiddot41-9-10 9~91 oas 262 S$1 1150~ 3 o 292 1-9-11 o9o u57 12JiO 21gt 26-77middot74

-45 26sect ~middot91-912 $69 091 sas 25 middot3 1)0$ 196 2J-8 1-9-1) 220 098 426 2)9 178 1390middot 84 16 6

0 0

Appendx C CALCULATED DATA (Continued)

Turbine Run Generator Generator lurbine Turbine Eft1e1eney Turbine lurbine Spee1f1c

Number Output Losses Outit Input Speed Output SPed middot k_-V KW R _ H_bull_P Percent r Thm HP rpm_ (9) tlo) 11) middot (12 _) (lJI ( ) (1$ (14)

2-9-1 9--46 055 1)62 258 528 580 164 2-9-2 1024 056 248 58 4 665 4 9 191iimiddot48 4~middot0 2-9-3 1132 067 05 2$0 641 795 52q 237 2-9-4 1148 065 1027 2$1 -~8 845 525 252 2-9-5 11 77 oso 16-83 253 6 910~ 522 270 2-9 6 1122 071 1600 251 622 960 47-5 2722-9-A 1092 015 1562 257 608 1010 445 2z12bull9- 1052 079 1514 261 580 1060 41middot7 2 2 2middot9-9 986 o82 ]429 26) 542 1105 372 277 2-9-10 915 086 1340 268 500 1160 334 27-6 2-9-11 638 087 972 254 )81 1270~ 229 250 2-9-12 )28 090 828 259 )19 1295 179 226 2-9-13 192 094 383 2$ 6 150 1370 7 3 152

-3 0

Page 2: The Effect of A Variable Draft Tube Flow Area on the

Srr[ ffiHttlf f nralE

ffi frurld rr TmS fir6

Ioryw lltDilr0 I0 rfrq

Redacted for Privacy

rilE 0 r4mrro lmur rs ur-Ttqamp

Redacted for Privacy

trfrrryIlW ITITS ge lumrrE silrfrtHt

Redacted for Privacy

mftr o r8rne uf ffrTo Jc iprmJHa

Redacted for Privacy

rffilgtrIIY

or the many persona who have shown interest and

offered assistance in the progress or this investigation

certain ones merit special acknowledgment

In particular gratitude is expreased toward H G

Barnett Head or the Depaltment of Electrical Engineering

L N Stone Associate Professor of Electrical Engineering

and w H Paul Profeasoll of Automotive Engineering tor

their generous supply ot advice and equipment J R H Shoebull

maker Jr Assistant Professor of Civil Eng1neering for

his help and photographic work G w Holcomb Chairman or the Department of Oivil Engineering and w c Weatgarth

Assistant Professor of 01vil Engineering for thea

cooperation and assistance in obtaining material and

auppllea J Thomas B Hayes and Vtetor N Bredbullhoett ot the

oonaulting engineering firm or Cornell Howland Raybullbull and

Merryfield for their suggestions and encouragementJ H D

Pritchett tor the photoglaph1c duplication B K Scoggan

R D Smith D D Sweeney R M Elder R L Polv1 and

W H Knuth ror their b1releaa ettorts in the taking ot

data and Mra Jeanne Nepoundf for her patience in t he typing

ot the final draft ot the thesis

lb1a investigation could have been neither started

nor finished without the inapirat1on1 ideas and criticisms

of Fl-ed Merryfield Professor ot Sanitary Engineering to

whom a special debt is owed

Grant Robley Aas1stant Dean or t he School of Engibull

neering or Yal Un1ver ity ia the cause or it all

Arl1sa D Ray

bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull

bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull

bull bull bull bull

bull bull bull bull bull bull bull bull bull bull

bull bull bull bull bull bull bull bull bull bull bull bull bull

TABLE Qf CONTENTS

Chapter

I INTRODUCTION bull

A Purpose and Scope of Investigation bull bull bull bull l B Reaction Turbinea bull bull bull bull bull bull bull bull bull bull bull bull 2 C Draft Tubes bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull 5

II DISCUSSION OF TURBI NE LOSSES bull bull bull bull bull bull bull bull 1

A General bull a Shock Loae ~ c Exit Loss 12

III PROPOSAL OF ALTERNATE METHOD OF CONTROL bull bull bull bullbull 14 A Type and Location of Control bull bull bull bull bull bull bull B Estimated Eftect on Actual Turbine bull bull bull bull ~ c Requirements tor Teet Verification bull bull bull bull 19

IV APPARATUS AND METHODS OP TESl bull bull bull bull bull bull bull bull bull 23

A Equipment bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull 23 B InatlWilentation and Measuring Devicbullbull bull bull 26 c Operational Pz-ocedure bull bull bull bull bull bull bull bull bull bull 26 D Schedule ot Rune bull bull bull bull bull bull bull bull bull bull bull bull bull JS

v DATA bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull 37

A Original Data bull bull bull bull bull bull bull bull bull bull B Calculated Data bull bull bull bull bull bull bull bull bull bull bull bull bull ~A

VI TEST RESULTS bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull 44 A Presentation of Results bull bull bull bull bull bull bull bull bull 44B Discussion of aeaults $1

VII CONCLUSIONS bull middot 56bull bull bull bull bull bull bull bull bull bull bull BIBLIOGRAPY bull bull bull bull bull bull bull bull bull bull bull 51 APPENDICES bull bull bull bull bull bull bull bull bull bull bull 60

A lfotation bull bull bull bull 61 B Original Data bull bull bull bull bull bull bull bull bull bull bull bull bull bull 6)c Calculated Data bull bull bull bull bull bull bull bull bull bull bull 67

bull bull bull bull bull bull bull bull bull bull bull

bull bull

bull bull

LIS~ OP_ __ ILLUSTRAfiOBS-middot

Fiere Page

1 13 $ Inch Reaction turbine bull bull bull bull bull bull bull bull bull bull 4

s bull bull bull bull bull bull bull bull bull bull bull bull

Plow Area bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull 4S

2 Turbine Runner Vector D1agrama and Shook Loaa Diaptama bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull 10

) Turbine PertoPmance CurYea bull bull bull bull bull bull bull bull bull bull 20

4 General View ot Teat Equipment bull bull bull bull bull bull bull 21

6 View ot Teat ut-bine bull bull bullmiddot bull bull bull bull bull bull bull bull bull 7 Teat Generator and Platform bull bull bull bull bull bull bull bull bull 27

8 Iutrument Board and Field Rheostat bull bull bull bull bull 27

9 Vlev ot Water lUteoatat bull bull bull bull bull bull bull bull bull bull 29

10 View or Water Rheostat bull 29

11 Vater Plow Diagram and Electrical Laout bull bull bull 30

12 Sketoh ot Draft ltlbe and Teat Inaerta bullbull bull bull 33

13 View ot Dratt Ube Inaer bull bull bull bull bull bull bull bull bull bull 34

14 Vlev ot Dr~t lube Iuert bull bull bull bull bull bull bull bull bull 34 lS Curves ot Generator Voltage Drop and Copper

Lose bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull 40 16 euvtee of Oenerator Stray Power Lobullbull bull bull bull 41 17 Turbine Charae ter1at1ca with lOOC Dl-att lUbe

18 Turbine Characteristicbull With 7SC Draft tube Flow Area bull bull bull bull bull bull bull bull bull bull bullbull bull bullbull 46

19 Comparleon Between 7S~ and 100 Pratt Tubbull Flow Areas ot Power and Etf1c1ency at OVer Gate Condition bull bull bullbullbull bull bullbullbullbullbullbull 47

bull bull

~ Q ILLt1SlATlOIS (Continued)

F1pe

20 Comparison Between 15 and 100~ Draft Tube Flow Areas of PoweP and Ett1c1enoy at Halt Gate Condition bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull 46

21 Oompu1aon Betwen S~ and 100~ Draft Tube Flow ANaa ot Po-r and Efflctency ab Ovbullbull Gate Condftimiddoton bull - bull bull bull bull - bull bull middot bull bull bull 49 Compar1aon ot Spec1tic Speeda tor 75~ middotand 10~ Draft Tube Flow Areae bull bull bull bull bull bull bull bull so

I

bull

filE EPPEOI OF A VARIABLE DRAFT TUBE FLOW AREA

ON THE PERFORMANltJE OF A REAOTIO TURBINE

Chapter l

IITRODUClIOH

A hrpose and Scope of Invst1pt1on

Present day control of reaction turbines is accombull

pl1ahed by the use of wicket gates immediately- preceding

the turbine runner These gates otter an interrelated conbull

- trol to the quantity and direction ot the water entering

t-he runner ie a change in the amount ot flow will rebull

middot ult in a change in direction This combined control leada

to loesee at all but the rated or design condition ot the

turbine (2$ Pbull )71)

This investigation dealt with an att mpt to better

turbine performance at all points of operation b y the

eatabliahment of separate controls over the rate of flow

and the d1J~ect1on ot the entering watebullbull

The only physical modification of the test tlutbine

was the insertion of flow restricting device in the dratt

tube

Ot primary interest were the trends in the change of

2

turbine performance with the amount ot draft tube tlow

area To this end complete turbine charaeteristiea were

not obtained tor 0ach device inserted in the draft tube

It was considered sutt1e1ent to obtain data tor the tull

speed range tor two representative gat openings one

greater and one less than the rated gate openingbull

Before proceeding with th report ot this 1nvest1gabull

t1on it 1a desirable to supply sa b ckground m terial

on reaction tw-blnes and their dratt tubes

B Raot1on 1rbinea

A hydraulic turbine is a device for converting the

energy in water to eohanical energy (6 Pbull 93lbull96S) furbull

b1nes may be loosely grouped into one of three elasse

impulsmiddote 1 reaot1on or propeller

An impulse turbine normally operates under a high head

and with a relatively sma~l amount ot watel in the converbull

sion or kinetic nergy to mechanical energy The propeller

turbine utilizes pressure energy to develop mechanical

energy while under a low head and p ss1ng a large amount of

waver

The reaction turbine lies somewhere between these two

extremes It changes both pressure and kinetic energy

while oper ting under a medium head with a moderate ount

opound water An example or a reaction turbine is pietur d in

Figure 1

lhe terms of high low small and so tomiddotrth are only

relative in sense A turbinebulls class1f1 eat1on is depenfent

upon its hoad rate of diacharge and speed of rot tion A

useful index tor turbine comparison (5 Pbull 825) is termed

specific speed and this ia a function of the rated ipeed

power output and head or the turbine The common range in

values ot speoitic speed ($ Pbull 826 ) tor each type ot tlirshy

bine is

Impulse J to SS tor one nozzle)Reaction bull 22 to 80 Propeller - 85 to 170

The development of t he reaction turbine began in the

early part or the nineteenth century (26 Pbull 1217bull1)6)

The trst efficient inward tlow turbine was de igned by

James B Francis an American in 1649bull For many years

turbine design was a matter of cutbullandbulltry in America an4

pure mathematical analysis 1n Europe It was not until the

two schools began exchanging ideas in the l$tter halt ot

the n1neteenth century that pronounced advancement was made

in the field

ObTioual7 the primary pux-pose ot any turbine inatallabull

t1on is t he production of power Added to this is the

restriction that the production or power must necessarily

be a controlled process An example of this is where the

turbine is direct-connected to an electric generator which

4

Figure 1 - 135 Inch Reaction Turbine

5

must operate at a constant speed or rotation even though _

the power demand ohangos In thiamp case the turbine nuet

be eap~able or producing a range of power output yet menshy

ta1n e eonetant speed

Speed regulation of the turbine iv accomplished by

means ot a governor (23 Pbull 24bull3-7) bull The contr-ol or regulashy

tion 1s indirect that i s the governor actually exereiaabull

control over the water in order to JJaintain e given speed

Co-ntrol over- the turbine end bence its speed and

power is the function ot a ring of movable wicket gates

located just upsttteam of the turbine runner These w1eket

gates 1n the process of opening and closing upon eeeh

0~1ar in a rotational manner actually control the amount

velocity and direction of tne water passing throu~~ them

C Draft Tubes

It has been found that the effeetive head on a reae

1l1on middotturbine is increased with the addi timiddoton of a draft tube

(3 Pbull 256bull264) Tne draft tube does thin by~

(1) Making a greater presaure d~op across the turbine

possible by the creation of a negative pressure at the

discharge or the runner and

2) DeoreaGing the k1net1e energy lost by increasing

the eross sectional area at exit

he draft tube permits the turbine runner to be

6

located above the tail race water surface without the

sacrifice of head However cavitation will cause pitting

of the turbine if the difference in elevation is too great

A common maximum elevation difference is 19 feet although

this figure is quite subject to modification between difshy

ferent installations (3 p middot 264-266)

There are many different types or draft tubes in use

today the choice or type being largely a matter or

economics (2$ p 368-370) A very common type particushy

larly among the smaller units is vertical with flaring

sides However the angle of flare is limited by the possishy

bility of separation of the flow from the sides In order

to achieve a certain discharge area the length of the tube

may be such as to require a great deal of excavation In

oases or this sort the cost of this excavation must be

balanced against a more elaborate design that does not

require as much excavation Other draft tubes in use

include the elbow hydracone and spreader types

Despite the differences found in construction and

design the draft tube must accomplish the desired objecshy

tives while offering a good hydraulic geometry to the flow

passing through it An inefficient draft tube defeats its

own purpose

Ohapter II

DISCUSSION ~ TURBINE LOSSES

A General

lhe head that 1a actually utilized by the turbine 1a

less than the effective bead as defined by equation ($) by

the amount that 1a lost due to mechanical and hydraulic

reasons

Mechanical loaaea are a function or the turbine 8p$ed

fhis ia not a lineaz- function but varies eomewhere between

N and N2 (3- Pbull 224)

Hydraulic losses encounteled in turbines ma- be subshy

divided aa to the location or occurrence (3 p 225-227) aa

fOllOW$S

(1) Penstock and scroll case

(2) Wicket gates

(3) Between wicket gates and turbine runner

(4) Runner passages

(5) Runner exit into draft tube

(6) Draft tube and

(7) At exit from the draft tube

The flow in the penstock scroll case wicket gates

runner passages and draft tube may be envisioned as

examples of flew in conventional pipes elbows and convergbull

1ng passages If this comparison may be made it could be

assumed that the losses encountered in these locations

would be proportional to vn ~ value ot N is normally2g

aesU111ed to be 2

he losses encountered between the wicket gates an4

the turbine runner and exit lossos are special cases which

will be discussed separately

B Shock toes_

The flow betwe n the wicket gat outlet and the runner

blade entrance is or particular 1nt rest because no direct

comparison vith common flow situations is obvious

Conaider the vector diagram (7 Pbull 7576) in Figure 2

The veetoo v1 is the absolute entering velocity of the

water and is fixed in magnitude and direction by the setbull

ting or the wicket gates The vector l11 1e the peripheztal

velocity of the runnel which tol any given turbine 1e

dependent only upon the turbine rotational speed The

combination of these two vectors ylelda the third vector

v1 which is the relative entering velocity ot the water

nere is only one setting ot the wicket gates for a

given turbine a peed that will produce an angle B1 which

coincides with the blade angle B1bull At other gate settings

the vector v1 will rotate and change in magnitude in such a

9

t ehion that B1 will beoome either greater or 1 sa than B1bull Th1 give rise to tbe phenomenon term d shock loasft

If B1 1a greater than B1 the relative ent ring veloebull

ityt v1 will have a compon~nt opposing the forward motion

of the runner The shock loss could be typified bullbull that

occasioned by direct impact or the water 0n the blade- If

E1 is lese than a] the vector l will overshoot the blade

and the flow will tend to eddy around the forward portion

or the blade tip

The shock loss can then be either due to impact or

eddying flow Since the area norm 1 to the radius at outlampt

of the w1eket gftee is essentially equ 1 to the area normnl

to the rad1u~ at the inlet to the turbine runner the combull

ponents ot vl and vl perpendicular to ul will b approxishy

mately equal This leads to the conclusion that xxbull ~epresenting the shock vector 1 parallel to Ulbull

For either the impact or eddy case the trigonometric

law of $1nee leads tot

XX

bull ul - sin (Bi-Al) vl eln Bi

It it 1a assumed that the energy lost in the shock 1a

the Telocity head ot the shock component XX then

10

VELOCITY VECTOR DIAGIWI

TYPES OF SHOCK LOSS

xbull X

IMPACT BDDJ

XX 1a Teloc1t7 caponent ot shock

Figure 2 - ~bine Runner Vector Diagram$ and Shock Loss Diagrams

11

2 shock loss (XX gt2g

C =sin (BimiddotAl)Let (1)sin Bi

(UlmiddotCV1)2Then shock loabull (2)- 2g

For a given gate opening C ia a constant ranging

from about 14 to 10 For a well designed wheel it is to middot

be expected that C would be approximately equal to U1V1

at rated conditions ie at point of maximum efficiency

This point will occur in the neighborhood of 3~ to 78

gate opening for moat turbines For overgate conditions

the angle A1 becomes larger so the value of C would

decrease For gate openings below rated conditions t he

angle A1 decreases and C would decrease One could expect

a fairly uniform decrease in t he value of C as the gate is

closed from t he overgate position

The velocity v1 is approximately constant for any

turbine speed since the area and rate of flow both decrease

fairly uniformly However for a given gate opening the

velocity V1 will decrease with increased turbine speed

From the foregoing comments and equation (2) the

following trends can be established

(1) For constant turbine speed the shook loss curve

will be close to parabolic in shape concave upward and

have its maximum near t he point of complete gate closure

--

12

and its minimum near the rated gate position

(2) For conatant gate opening the shook loss curve

will approximate a symmetrical parabola with its vertex

the point of minimum loas located at the rated condition

of operation (7 Pbull 79)

c Exit Loas

It can be seen from Figure 2 that the exit loss from

the turbine would be v222g if no draft tube were present

The addition of a draft tube permits the gradual reduction

of velocity by an increase in cross sectional area between

the exit of the runner and the exit from the draft tube

The exit loss and the frictional loss encountered in

the draft tube may be placed together in the expression

m va2 (3)Exit Loss ~---2g

For the ideal case of no friction in the draft tube

m is equal to the square of the ratio of the area at exit

from the runner to the area at exit from the draft tube

In an actual turbine installation however friction

will change the value of m (7 p 84-85) to somewhere

between that for the ideal case and a maximum ot 10

In the interest of maintaining a minimum exit loss

the turbine should be designed and operated so the velocity

V2 will be minimum This will occur when the discharge

13

vector is at right angles to the tangent to the runnerbull

ie the angle A2 1e ninety degree bull It ia to be expected

that this condition will be tultilled near the design con~

d1t1ons ot the ~bine

Current design praetiee 1 to have a small component

ot v2 in th$ direction of turbine rotation at rated condibull

tion$ ltS p 938)

For a constant turbine speed the d1seharg or exit

loss is ess nti lly a constant

For a constant gate opening the exit lo s curve is

aptrroximately a symmetrical pa~abola with ita vert x the

point or minimum loss located at a slightly lowe~ speed

th n the turbine rated speed (7 Pbull 79)

Chapter III

PROPOSAL OP ALlERMAlE MFTBO 0 CO TROL-A lz ~ Location 2 Control

Thua tar only practice and theoretical aspects appemiddotrbull

taining to present day turbinea have been d1acuaaed It

haa been presented that control over the ~bine ia ezerbull

oiaed b y manipulation of the wicket gatea located 11101led1bull

ately preceding the runner These gate - upon rotation

modify both the magn1tu4e and the direction ot the entering

velocit7 Moreover it has be n shown that a simultaneous

change in these two variables leads to inefficient operabull

tion by the introduction of shock loss he farther the

point of operation a from the rated conditione the more

aerioua ia the ahock loss encountered

Any attempt to better turbine pertorance at other

than rated conditione and tbne flatten the top ot the

etticieney hill8 must concentrate upon the lessening ot

the ahock loaa It 1a a aumed that 1 provement in the

scroll case gates and runners would lequ1re sueh pertecbull

tion 1n machine work and metal$ as to be prohibitively

expensive

It ie surmised that any move to elblinate eYen parbull

tially the shock loss would require separate control ovel

l$

the flow and gate exit angle Since it is improbable that

d1~ect1on could be controlled at any location other than

where the gatea are situated in current turbines it will

be assumed that guide vanes will be necessary regardlesa or the method used to control the rate of flow

The primary purpose ot th se guide vanes 1s that or control over the direction ot the incoming water They

should be free to rotate in much the same manner as ordibull

nary wicket gates in order to exercise control over th

turbine speed

If the rate ot tlov is to be controlled elsewhere it

must be modified either in the penstock or the draft tube

Devices that could be used are standard valves gates

variable orifices variable venturi sections and associated

flow regulating schemes

Alauming it were decided to locate such a device upbull

stream of the turbine it would be necessary to allow disbull

tance tor the flow picture to become reestablished prior to

entry to the turbine A contused flow making transit of

the turbine passages would only contribute additional loesbull

ea Such a distance allowance would be perbapa 20 to So

diameters (2$ Pbull 119-123) In large penstocka th1a would

repreaent a considerable distance Which from the viewbull

points ot convenience and control would be undesirable

Attempts to ascertain the effect or additional tlov

16

reduc ion at the wicket gatctsmiddot wae ade 1n the lfadraulioe middot

Laboratory of Oregon St middot te College in 1933 (20) Three

d1tterent thode ot reducins the tlow were t~ied

(l) Locking in the cloeed position pairs or wicket

gatea located opposite to eaeh o~er on the -periphery ot

the wheel

(2) Locking adjacent gates in an open position by

inserting blocks of wood between them and

()) Suocess1vely looking adjacent gates in the closed

position

The results indicated a arked reduction in both power

and efficiency when compared to the curves tor normal gate

operation However it was demonstrated that it was poae1bull

ble to ahitt the power and tfieiency curve ill relation to

turbine apeed lbis important feature will be diacussed

later

ihe main conclusion of the investigation was that conbull

trol by the conyent1onal wick t gates was auper1or to other

methode egtt control exercised at the gates the aelvebullbull

It would app$ar that the bebullt location tor flow conshy

trol would be in the draft tube since none of the objecbull

tiona prev1ously mentioned wou~d eziat there

As bas been stated previously the sole object or the

17

18

turbine is to produce power as etfic1ently as possible

The equation tor the power output of a turbine () Pbull 227)

PaWHe HP (4)55o bull bull Assuming the head 1a constant and a g te located in

the draft tube decreases bhe rate ot flow the power eu

only be increased if the etticiency increases

The ettective head Gn the turbine 1s conventionally

d r1ned as the difference between the auma ot the elevashy

tion head pressure head and velocity head at the entrance

to the turbine casing and the tailrace ($ Pbull 872)

lt ie recognized that the theoretical treatment ot

shock loss as given is highly approximate and serves only

to dictate certain trenda For example the area at xit

rom the wicket g tea CfUl be measuPed with some exactness

but there exists no guarantee that the wateP particles will

complet-ely fill the apace oz- will exit at the establiahed

g te angle The same can be said of the exit trom the

runner blades AssUIlptiona were implied which would indishy

cate that all water particles passing a given croea section

ampH traveling at the same velocity in the same direction

the e alone are autt1c1ent to show 11m1tationa in a theoretbull

1eal approach to the problem

Assume a turbine with ordinary wicket gates tor oonbull

trol compared gainst the same turbine with a gate in the

18

draft tttbe tor supplampment1ng control or the rate ot rlow

Let it also be assumed that the two turbines are opershy

ating at the same point It 1s desirable to predict relabull

tive performance of the two turbines 1 this point of

operation is such that edd7 s hook loss ot reasonable proshy

portions is present in the fir t turbine

~ tull erteot of the shock loss will be exper1 need

by- the fir t turbine

lhe second turbine will derive certain advantages 11

the gate in the draft tube is adjusted to reduce the tlov

1n the proper amount Since they vary a the square ot

the veloo1t7bull the lossabull in the aeroll case wiomiddotket gate

and runner passages will decx-ease aetet-r1ng to Figure 2 1

it can be seen that a decreased velocity v1 w-ill reduce the

eddy shock losa

The ent loss in the dJtaft tube of the second turbine

will be the sum ot the tr1ct1onal loss and the velocity

head at ex1t The velocity head dissipated will be greater

due to the closing action or the gate but the reduoed

t~ictional loss which ia a tunction ot the rate of tlow1

will partially balance this

It 1a entirely possible that the net reduction in

losses in the second turbine will lead to a greater ettibull

oiency and more power output than 4eYeloped by the first

turbine

19

In Figure 3 the plot ot power output against turbine

speed for Curv A~ represents the typical family of curvea

tor a reaction turbine Th b st sp ed is the locus ot

points connecting maximum eft1oiency at each gate opening

The operating speed is the coZUJtant turbine apeed which

passes through the point ot maximum efC1ciencr of the turbull

bine The plot of turbine efficiency against power output

for Curve A is also ahown

It the turbine with flow regulation in the dratt tube

oan demonstrate superior power and efficiency at part loads

the effect would be the same as a shifting or the power

curves toward the condition shown fop Curve B 11 Thisbull

illustrates th ultimate case of the uperpoait1on of best

and operating speeds It will be noted that the pet-form~

of the turbine ot Ourve Bu 1a better than that of CUrve

A at part loads because of ita ability to sustain a relabull

tively high etticienoy ovel a Wider range of power output

o Reguireaegts tort Test Velitication

It is desired to deterra1ne the effect on the turbine

performance b) the addition of a gate in the dratt tube

Th step in the teit will bet

(1 To determine the power output and efficiency ot

the turbine tor wicket gate settings above and below rated

conditione for a wide range ot speed

20

CURVEAbull

TURBINE SPSBD TURBID SPEKD

POIBR OOTPOl

Figure 3 - Turbine Performance Curves

21

22

(2 peat (l) with the gate installed in the drat

tube

(3) middot Converting middot all data to a constant head compare the

powere and effioiencies at the same wicket gate setting and

turbin speed tor the two cbullses

If the ddition or the gate indicates an improvement

in power output and efficiency and the powe~ curve shifts

to the right along the turbine apeed scale the advantage

ot draft tube con~ol of the flow will hav been demonshy

strated

Chapter IV

A E9J11pment

ih turbine used in this test is lJ 5 1nch Pelton

reaction turbine with a rated output ot 30 horsepower under

a head of 56 feet at a speed ot 720 reYolutiona per minute

Views of this turbine are hovn in Figures S and 6 The

turbine is installed on a concrete pad located over an open

channel in the Hydraulics Laboratory at Oregon State Colshy

lege The date of manufacture of this turbine was 1915

The water was delivered to the turbine from a sump

reservoir by two pumps operating 1n parallel Each pump 1a

an 8 inch Pelton double suction centrifugal pump witb a

rating of l$00 gallons per minute at a head ot 75 teet with

a speed ot 1175 revolutions per minute Tbe inlet tlange

ot tne turbine is $pprox1mately 18 feet above the center

line of the pump

A direct current generator was coupled to the turbine

to receive tne power d veloped as shown in Figures 4 and 7 The generator is a Spr gue Electrodynamometer rated at SS horsepower with a speed range of 7$0 to l$00 revolut1one

per minute The classification is type LO 26A 2)0 volta

Figure 5 - View of Test Turbine

Figure 6 ~ View of Test Turbine

and 149 amperes lbe generator ti ld was aepar tely

excited using direct current from a motor g n r tor ampt

(l$ p 4~8)

The power output of the generator waa dissipated in

the water rheostat (3 p 488-489) shown in Figures 9 and

10 The galvanized tank contain d water ot variable d pth

on an electrode ot cast iron m aauring 1bull x 1 x 1

In the initial installation of the turbine it was

intended that the power output should be measured with a

Prony brak bull For th purpoa68 or this teat it was decided

that the brake was too instable and the generator was

substituted The platform for raising the generator the

nee asary two teet for alignment was built out of available

material In this case heavy laminated wood blocks reiashy

torced with other timbers were used and bolted through the

concrete deck (11 Pbull 36-$7)

Due to the light concrete deck the lack ot mas in

the platform and the slight misalignment in the flexible

coupling ao e vibration waa encountered It seemed to

ncr aae linearly to a maximum at the speed of bout 750

revolutions per minute Above this speed no vibPation was

noticeable The vibration waa not se~ere and does not

appear to have materially affected the test results

26

B Intrumentat1on ~ eaeur1ng Devices

The pressure head at inlet to the turbine vaa meaave4

bymeane ot two )6 inch waterbullmeroury manometerbull connected

in series as shown in Figure 8

The terminal voltage ot the generator vas meaeured by

a laboratory voltDleter with a range to )00 yolta and callbull

brated to within 15 Yolta

The armature current bull and hence the line current was

measured by a laboratory ammeter with a range to 150 amperea

and callbrated to w1 thin o 7S amperes

Tae rate ot tlow was established by weight and time

meaeurementa The weighing ank has a capacity ot 121 000

poundsJ the weight belng indicated by Toledo direct reading

scales Timing was done with a hand atop watch with clivibull

aion ot 02 second

he ~ater level in the tailrace was dete~1ned by a

hook gauge lhie was read to the nearest 001 toot

The turbine and generator speeds were eaaured by a

hand tachometer The technique of almost cont1nuoua readbull

ings of the speed gave an error ot no more than 5 revolubull

tiona per minute

c Operational Procedure

Atter the water level in the aump was checked to

insure an adequate auppl7 the puapa were primed and

27

Figure 7 - Test Generator and Plattorm

Figure middot8- Instrument Board and Field Rheostat

28

started After venting they were valved for operation 1n

parallel

The motor generator set was started to supply the

field current and the circuit breaker was closed Water

wa added to the water rheostat to the level shown in

Figure 10 ~ field current wae minimized by cutting in

all the f ield resistance in the field rheostat of Figure 8

The l2 inch gate valve shown in Figures 5 and 6 waa

slowly opened and the turbine and generator brought up to

speed The 12 inch gat valve and turbine were vented and

the pumps were checked to insure neither had lost ita prime

lhe water rheostat offers very steady load 1f the

water level is essentially constant and the water temperabull

ture 1a fixed () p 488~89) In order to maintain this

constant temperature it was decided not to circulate the

water in the rheostat but rather to allow the water to

boil thua achieving the desired result A standing wave

was set up on the face ot the electrode by the boiling

action but a atable load was eatablished except at very

low water leYels where th11 agitation led to fluctuationa

in the line current

After putting the turbine and generator on the line

maximum power was dissipated in the rheostat by redueing

the turbine speed to between oSO and Soo revolutions per

minute Salt vas added to the rheoetat wat r to increasemiddot

29

Figure 9 - View of Water Rheostat

Figure 10 - View of Water Rheostat

Separate Field ExcitationFrom Motor-Generator set Compound Water-Mercury

---shy

re Manometer

I Q)

~ 0

~

Book Gauge

Open Channel

I

Slap Reservoir

Figure 11 - Wat~r Flow Diagram and Electrical Layout

31

waiting pe~iod ot perhaps an h~ followed

while the boiling point or the water wbulls reacbe4 During

this ti+ne the manometer was vented end eheoked electrical

measur1ng 1nstlUments were connected end the hook gauge was

adjusted tor elevation

It required about two- houtte tor the generator to reach

its normal operating tempe-ratu~e_ After the water in the

rheostat and generator had reached their operating temperabull

turea it was possible to begin the taking of data

The only vaPiable which was controlled wee the turbineshy

generator speed However the upper l1ut1t of safe line

current was slightly over 100 ampJilPampPes and the eireuit

breaker would open when the current reached lOS ~ere bull

Control was exercised by means ot regulating the water

level and salt 1n the water rheo tat and the res1stsnoe of

the tield rheost t~

The etfeet ot each type ot regulation on the three

variables is shown below

Volta Aaperebull Speed

Inc Dec Inc Dee~ Inc Dec

Wa~e1 Level Inc Dec~ X

X X X X

X

Salt Concentration

Inc Dec X

X X X X

X

field Resistance

Inc Dec

X X

X X

X X

32

Jlot all methods gave the ame amount ot change in a

given variable and a period of experiment and trial led to

the following scheme starting the rune with the lowest

turbine speed the water level was high with a high amount

ot salt and the field resistance was cut completely out

Aa it became necessary to increase the speed tor each

aucceasive run either cutting in t he field resistance

decreasing the salt concentration or lowering the Vater

level would produce the desired result However decreasbull

1ng the salt concentration had to be done Without a net

gain in water which led to a tluahing procedure that was

not particularly good because cold water was introduced

which required time to heat to the boiling point Cutting

1n additional field resistance was a good method but th1a

increased the amperage possibly to the point of opening

the circuit breaker Lowering the water level was aatiashy

factol1 until the level got too low causing the current

fluctuation previously mentioned Actually it turned out

that a combination of lowering the water level and cutting

field resistance in would carry the speed from ita minimum

to 1ts maximum value it the proper choice were made each

time the speed waa to be changed At the conclusion of

each aet of runs at a high speed the water level would be

low and the field resistance high

33

TURBINE

PAD AND DECK

TAILRACE

WATER SURFACamp

CONCRETE

DRAFT TU1B INSERTS

7 5( DRAFr TUBE

FLltJI ARIA

5~ DRAFT TUBE

FLOI ARSA

Figure 12 - Sketch of Draft Tube and Test Inserts

34

Figure 13 - View of Draft Tube Insert

Figure 14 - View of Draft Tube Insert

D c __ ~s_middot hedu_le of

A number was assigned to each run The fi~st number

applies to the draft tube tlow areas

1 bull 100~ flow area or 0~ oonatriction

2 - 7S tlow area or 2$ conatr1ct1on

3 SoC flow area or so~ constriction

The second number refers to the wicket gate openings

9 over gate opening

6 bull intermediate gate opening

4 bull one h lt gate opening

The third number 14entif1ea the location of the particular

1Wl in a set ot rona made at a given dratt tube tlow area

and wicket gate opening

fnua run number 1bull4bull10 would identity this as the

tenth run ot a set made at halt gate with 75 ot the draft

tube t1ow area

Rune w re made tor a g1yen dratt tube condition

Firat tor tull 41-aft tube flow area seta ot rune were

made for the overgate halt gate and intermediate gate

conditione An insert was placed in t he draft tube and

rune based on the same gate conditions were made tor the

7S~ draft tube flow area case The insert was then changed

to allow only $~ draft tube flow area

The inserts are sketched 1n Figure 12 and photographed

ln Flgurea 13 and 14 They oonaisted of circula~ segments

36

or l2 ineh plywood mount 4 on wooden legs 10 inches high

The 1nse7te were placed in position and secured by th use

ot a-clamps on the legs and the outside ot the bottom of

the draft tube The obvious disadvantage to this method

waa the neoeasity tor draining the water from the tailrace

tor a change ot 1naert The advantage vas of course the

simplicity ot design and construction

Chapter V

DATA-A Original Data

The normal data-taking crew consisted or two men

Assuming adjustments having been made to secure a certain

turbine speed (aee section on Operational Procedure) one

man would take semi-continuous speed readings with the hand

tachometer until a state or rotational equilibrium was

reached This could be only a period or two minutes up to

ten or tifteen minutes As soon as steady speed was

assured the data taking would begin The second man went

to the weighing tank Where a minimum ot three weighingamp

were made The requirement was to get three consecutive

readings such that the ditterence between tbe smallest and

largest time did not exceed 04 seconds The time to

collect a given weight ot water was then assumed to be the

arithmetic average of the three times He then went to the

hook gauge determined the hook elevation and then

recorded the data on the data sheets The first man meanshy

while had taken readings of the line voltage line current

and manometers and checked the turbine speed by multiple

readings During the length of the run all values were

38

checked to determine mean values for recording

The minimum length of one run was about five minutes

If one or more measure ants tended to drift during the run

all values wer discarded and a new run began as soon aa

qu111br1um was stabl1shedo

B -0-al_e_u_l_a_t--d Data

The h d on the tu~bine 1 defined by

($)

The maxtmwm velocity V4 was equal to about o8 tampet per

secon4 which makes it a negligible quantity when converted

into velocity head

An engineerbulla level was used to deterine the d1ffePshy

ence 1n elevation between the compound water-mercury manoshy

meter and the hook gauge Using this value the equation

for turbine bead becomes

where z4 is the hook gauge reading

The rate of flow 1 cent

w weight or water collected average time to collect

The inlet velocity v1 vas calculated by dividing the

weight rate or flow by the specific weight of water and the

)9

area ot ~e inlet pipe This was equivalent to dividing

the weight rate of flow by 490 Then the power input to the turbine is equal to

WHpin rri

10 (6)

Also

(P ~ut) Turbine

(P out) + Generator

(P lost) Generator

The power output of the generator is simplJ the

produot ot the terminal voltage and the armature (line)

curPent The power lost in the generator can be subdivided

into copper losses and stray power losses lo evaluate

these cunes based on losses of an identical generator

11leampsured by the Department ot Mechanical Engineering were

used The loss curves are reppoduced in part in Figures

15 and 16

Determination ot generator losses proceeds as tollowau

(1) From Figure 15 detem1ne the vo1tage drop in the

armature circuit using the temperatures of 1220 F and the

meaaured current

(2) The induced voltage is t~e sum of the terminal

voltage and the voltage drop 1n the armature circuit

() Entering the induced voltage and the turbine speed

into Figure 16 the stray power loss can be determined

(4) The copper lose can be evaluated from Figure 1$

using the measured current and the temperatlll-e of 1220 P

40

25 ~------~--------~--------~------~

U) -U) - 20

f-4 ~

-~ -gt 0

0

VOLTAGE DROP

~ - i -

- bullbullbull bull - -middot-middot -+ ~- + -t--+ ~ - ~ middotbull ~-~ middott- -+----- _ -4 middotmiddot- --~-+-t---r~~ ~--+t-t- - ---t-c-++~-ulf--

0 50 75 100

Figure 15 - Curves of Generator Voltage Drop and Copper Loss

41

1200

1000

800

600

800

0

0

~-

middot--~ 1shy --1 + bull l

100

I -

150 200

IIDOOED VOLTAGB (VOLTS)

Figure 16 - Curves of Generator Stray Power Loss

_ j

-bullshy -L---- shy middot -shy

250

- r

42

(5) The generator los os equal the sum of the eopp r

loss and stray power loss

~e efficiency or the turbine is taken as

etticiency u e =P out (8)Pin

~ample pound Determ1n1gg turbine Power Output

The following data are taken trom that ot Run 1-9-1

Line voltage 1040 volts Line current 870 amperesSpeed 355 revolutions per minute

The induced voltage 1a determined as follows

Line voltage 1040

Voltage drop 90 using Figure 15 with line current of 870 amperes and temperature ot 122 degrees)

Induced Toltage 1130 volta

The power output of the turbine is determined as follows

Generator output 90$0 (line voltage z line current)

Oopper loss 7 (using Figure 15 with line current of 870 amperes and temperatUe or 122 degrees)

Stray power lose 470 (using Figure 16 with speed ot 355 revolutions per miDUte and induced voltage or 1130 volts)

Turbine power output 9527 vatta

or turbine power output 1s 12z2 horsepower

43

The conversion of the calculated data to a constant

head is based on the conventional assumption of constant

efficiency regardless of turbine head For a constant head

ot 81 teet a purely arbitrary figure the tollowing relashy

tionships are ass1lJiled to be true

I ____L (9) (i)l72

(10)

For these two values the specific a peed may be combull

putedt

N t Jt VPt (11)8 243

Chapter VI

~RESULTS

A -Pr_e_ae_n_t_a_t_t_o~n g Reaultbull

Graphical presentation ot the results ot this te1t

are given as follows

Figure 17 -Turbine characteristics with 100~ dratt

tuba 1low area

Figure 18 - Turbine characteristics with 7S dratt

tube tlow area

Figure 19 bull Comparison ot power and etticiency at

over gate conditions between 100 and

75~ draft tube flow area

Figure 20 bull COZQparison of power and ettic1ency at

halt gate conditions between 100~ and

7S~ draft tube flow area

Figure 21 bull Comparison of power and etticiency at

over gate condition between 100~ and

So dratt tube tlow area

Figure 22 - Comparison in variation ot apec1t1c

speed between 100 and 75~ dratt tube

tlow area

50

45

20

-bull - 1--shy40

bull J-~ 30

~ ex

~ 20

~~ ~ -)q

I

~ - _

- -

10~ OF DRAFT TUBE FL(Jif AREA

CONSTANT HEAD OF 8l FEST10

POIER OUTPUT EFFICIENCY SPECIFIC SPEED

0 ~--------------_--------~------~------~ 400 600 800 1000 1200 1400

TURBINE SPEED (RPM)

Figure 17 - Turbine Char~cteristics with 100 Draft Tube Flow Area

50

46

-bulllle

~ 7 ~ OF DRAFt TUBE FLOW AREA

0 -~~-rl C05STAMT BEAD OF 81 mET 1J~

POIER OOTPUT ---+- ---o ~_H EFFICIDCY ~ I shy

bull ql SPECIFIC SPEKD - ~ -

bull ~ J 10 L rmiddotr- r- -

bullz- I

~~ 30 ~~--~----~~-

20 ~ ~ middot-shy

26

~~ 25

~0 ~r-----i (

Tbull -bullshy

400 600 800 1000 1200 1400

TURBINE SPEED (R PK )

Figure 18 -Turbine Characteristics with 75 Draft Tube Flow Area

47

EFFICIENCY 60

1-----shy

-~ 50~--~--~~-~middot middot middot middot r~-~----~~~~---4~-r~-~~gtt

II

POWER~ J ~ bull bull

u I

sH

40~------+-------+---- -~~--~~-~~~~

~----~rl 1 bull

I

I

0~--------------~------_------~--------

~ -OVER GATE CONDITION

COIJSTANT HEAD OF 81 FEET

0 o 10~ DRAFt TUBE

_-- _ 7~ DRAFT TUBamp FLON AREA II

10_~-----+--------r-------r----~~

400 600 800 1000 1200 1400

TURBINE SPEED (RPM)

Figure 19 middot - Comparison between 75 and 100 Draft Tube Flow Areas of Power and Efficiency at Over Gate Conshydition

48

t

bull --4 r ~- ~ middot~

70 1-----------+-~~~~~+middot ~ ~~ middot middot -~~--~~--------~~----~-+1

-~-

Atbull bull

lla-

60

amp0

40

20

10

oampOO

t _ - - ~-+- - -~-

l2 GATB COJIDITIOJJ

COJISTABT HJW) OF 81 JBET

o 0 lOQ( DRAFl TUB8 FLOI AREA

e-- - e 75 DRAFT TUBE FLOW AREA

800 1000

- r-

~

TURBIbull SPBIID (RPII)

Figure 20 - Comparison between 75 and 100 Draft Tube Flow Areas of Power and Efficiency at Half Gate Conshydition

49

60

50

-40

bull 30

IIQbull

20

10

0

400

- t - ~

EFFICIENCY

_J bull - bull bull

~ r r middot t -+ shy L -t -

OVER GAD COliDITIOI

CONSTABT BEAD OF 8l FBB

o o 10~ DRAFt TUBE FLOI ADA middot--- 5~ DRAF TUBE FLQPi AREA

600 800 1000 1200

Figure 21 -Comparison between 50~ and 100~ Draft Tube Flow Areas of Power and Efficiency at Ove~ Gate Conshydition

50

25

20

15

10

0

Figure 22

~- T -4 -t- -l --~-

t-~ I

middot --~- t ~---- _ __ _ + --

----~- --r-- --

~-=J-~-=-~ -==~ _ ~- -- ---f---1 - shy

CONSTANT HEAD OF 81 FEBT

o--o 1~ DRAFT TUBE FLltll AREA

75C DRMT TUBK FLCIJ AREAmiddot--middot-middot 600 800 1000

TURBINE SPEED (RPK)

Comparison of Specific Speeds for 75 and 100 Draft Tube Flow Areas

51

B Discussion 2 Result

Consideration of Figures 17 and 18 indicates the

overall eftioi ncy pattern or hill is significantly or

rounded for the 7$~ flow area than for the 100~ flow area

bia implies a greateP efficiency is possible at speeds

leas than or greater than design speed with an insert in

the draft tube However the muilDum efficiency is lemiddotas

Direct comparison at over gate conditions is made in

Figure 19 ~e same general trend is noted tor both the

etticiency and power curves for the 7$~ flow area case

The eurves show higher values at overspeed than do the

correaponding cWvea for the 100 flow area case It ia

not clear whether the curves have been shifted by the dratt

tube constriction or whether the curves simply bulge past

the normal curves at both overspeed and underspeed condishy

tions The power curves apparently peak near the aeme

point bullalthough maximum power is still obtained with the

normal draft tube area

For the comparison at halt gate operation shown in

Figure 20 a general improvement has apparently been made

by restriction of the draft tube flow area At every speed

the etticienoy and the power is greater for the restricted

tlow case The two ett1o1ency curves and two power curvea

are practically parallel throughout the speed range ot

teat

As the flou aroa i e decreased still farther a s1gn1

ticant change appears Reterr1ng to Figllle 211 tor the $0

flow area curves it a obvious that exit losses have

become excessive at the overgate condition because the

efficiency and power are everywhere leas than tor the case

of normal draf t tube area

Earlier it was pointed out t hat 1t the r esult s 1nd1bull

eated an increase in both power and ef tieiency- t hen it

could be assumed tha t the additional los s i ntroduced with

the draft tube insert is less than the diminished losses

due to leas shock losa and water passage losses For the

places where both the efficiency and power have been

increased we can assume that the insert has improved turshy

bine performance

For the places where the power haa been decreased

nothing can be said as to the elimination of ampbock loss

because the new lose present with the drat tube insert has

overshadowed any gains in eftecti Ve head upatJ-eam of the

insert

Near the peak of the efficiency hill howeve~ it may

be pointed out t hat shock loaa ie a minimum with a normal

draft tube and the insert merely adds an additional loss

with the resultant decrease in maximum efficiency tor the

7$~ flow area case

Perhaps the most s1gn1ticant set of eurves is shown aa

53

Figure 22 In this graph values of specific speed tor the

75 and 100~ flow area cases for both over gate and one

halt gate openings are plotted against turbine speed At

every speed and both gate openings the value ot specific

speed for th 75~ flow area case is greater than that for

the 100 t1ow area ease

Since the head is a constant for both situations this

may be interpreted in either of two ways trom equation

(11)

(1) For the same turbine apeed restriction of the

draft tube t1ow area resulted in greater turbine power

(2) For the same power amputput the turbine with 75~

draft tube flow area operated at a greater speed than did

the one with 100 flow area

Since the required diameter of a turbine varies

inversely with the speed the second interpretation could

be stated such that a smaller turbine could be used to

develop the same power output

Whether viewed trom the aspect of increased power

greater speed or reduced size the performance of the turshy

bine with reduced draft tube flow area is superior to that

with the nolmal flow are in the draft tube

The curve of specmiddotific speed versus turbine speed for

the so draft tube flow area case at over gate cond1t1ona

was not included in Figure 22 This curve lies below that

for the 100~ flow area c se at all speeds

In elaboration ot the second interpretation of Figure

22 attention is directed to the relative magnitudes ot

increased apee1f1c speed tor the two gate openings Assumbull

ing that the increase in specific speed implies a shift ot

the power curve to the right along the turbine speed scale

the power curve would be shifted more tor tbe halt gate

opening than tor the over gate opening

It thia trend could be extrapolated to the other gate

openings the tendency can be seen tor the line ot beat

speed to rotate toward the line of the operating speed as

illustrated in FigtU-e ) The advantage of this has already

been discussed

This particular turbine has a low specific speed tor a

reaction turbine Aa the rated value of apecitic apeed tor

reaction turbines increases the line ot beat speed departs

even more radically from the line of operating bullpeed It a

test similar to this were conducted on a reaction turbine

ot gleater specific speed it is pJobable t hat the rotation

ot the line of beat apeed would become more p~onounced

The scheme used in th1a teat had two obvious dr wbull

backs The first was the decision to leave all the wicket

gamiddottes installed tor all conditions ot the draft tube

These gates predominated in control of the tlow The

inserts added to the draft tube merely acted as auxiliary

55

contrGla

The aecond drawback was the choice or device to place

in the draft tube The reasons foll selection of this type

of device have been previously mentioned It is to be

anticipated that adaptation ot dratt tube flow control

would result 1n a better device for an actual turbine

installation Such apparatus might take the form of a

pneumatic bladder or a h7drau11oally operated variable

venturi section in the draft tube It is conceivable that

the gate as used in this test might be adapted also

Chapter VII

OONCLtJSIOfS

From the results of this test the following eonolubull

e1ona aa to the effect ot a variable draft tube flow area

on the performance or a r action turbine may be drawn

(1) The effect ot a variable draft tube tlow area 1a

generally favorable upon the operat1Gn ot a reaction turbull

bine because or the tendency tor the line or beat speed to

rotate toward the line ot operation This resulte in

better performance of the turbine at partbullloads

(2) he etf1o1ency eh111 tor the turbine beeomaa JDore

tlat at the top leading to a smaller max1JilWD effic1enc7

but e reater etticieney at other pointe of operation with

the insertion ot an auxiliary control ror the rate ot tlov

in the draft tube

(3) The power output of the turbine will increase at

over speed over gate conditione as well a at part gate

conditions with the proper amount or draft tube eonatr1cbull

tion or flow

(4) It is possible to eliminate at least partially

eddy type shock loss by tho introduction ot flow control

in the draft tube

BIBLIOGRAPBl

1 Addison Herbert A treatise on applied h-draul1cs New York Wiley 1954 724 Pbull

2 Allen o M and I A Winter middot Co111parative testa on experimental draft tubes Tranaact1ons ot the American ociety ot Civil Engineers 87t893bull970 1924

3 Barrows a E Water power engineering 3d ed ew York McGraw-Bill 1943 791 Pbull

Bovet G A Modern trenda in hydraulic turbine design4middot in Europe Tranaactions of the American Society ot Mechanical Engineera 75975bull993 1953bull

s Oreager William P and Joel D Justin Hydroelectrichandbook 2d ed New York Wiley 19$0 1151 Pbull

6 Daily Jamea w Hydraulic machinery Int Hunter Rouses Engineering hydraulics Hew York Wiley 19$0 p 8$8bull99

Daughertybull Robert L Bydraulie turbines ew Yorkbull7middot MoGrav-Hlll 1920 281 Pbull

8 Daugherty Robert L Inveat1gat1on of tne performance ot a reaction turbine ~anaactiona or the American Society ot Civil Engineers 7811270bull1304 1915

9 Davie L M Model and prototype testa Int Trend in hydraulle turbine practice symposium lranaactions ot the American Society ot Civil Engineers 1o63S3middot368 1941

lfJ Doland James J Hydro power engineering Hew Yorkbull Ronald 1954 209 Pbull

11 Gandy Theodore s and Elmer c Schacht Direct curshyrent motor and generator troubles operation and repair New York McGraw-Bill 1911 293 Pbull

12 Gibaon Arnold H Hydraulics and ita applications5th ed London Constable 1952 813 Pbull

58

13 Button s P Component loases in Kaplan turbinebull and The prediction of efficiency from model tests Probull coedings of the Institution or Mechanical Engineers168743-762 1954

14 Knapp R T~ Oavit t1on mechanics and its relation to the d sign or hydraulic equip ent Proceedings or tne Institution ot Mechanical Engineers 166150bull16) 1952

15 Langsdorf Alexander s Principles of direct curHnt mach1nee 5th ed New York r~cGrawbullH1ll 1940 746 Pbull

16 Lsrner Chester w Characteristica of modern hydraubull lie turbines Trans e~ions of the ~~erican Society ot Civil Engineers 66306-386 1910

17 Linsley Ray K Jr and Jobulleph B Franzin1 Eleshyments of hydraulic enginebullring New York McGrawshyBill 19$5 $82 Pbull

18 Mead Daniel w Hydraulic machinery llev York McGraw-Hill 1933 396 Pbull

19 ead Daniel w Water power engineering New York McGrawbullRill 191S 843 Pbull

20 Mockmore Charles A Part gate operation at water turbines Corvallis Oregon State College Department ot Civil Engineering 1933 11 numb leaves (Unpubshylshed typescript)

21 Mockmore Oharles A Flow characteristics in elbow dratt tubes Transactions of the Amez-ican Society ot Civil Engineers 103402middot464bull 1938

22 Moody L F Hydraulic machinery In c v Davis Handbook ot applied hydraulics New York McGrawshyHlll 1942 1082 Pbull

2) Ptau At-nold Hydrbullulie turbine handbook ld ed Milwaukee AllisbullOhalmers ManufactUIing Company 1948 70 Pbull

RheingalUI w J Recent developments in Francis turshybines Mechanical Engineering 74189-196 1952

25 Russell George E Hydraulica 5th ed New York Henry Holt 1942 466 Pbull

26 Safford A and E P- Hamilton American mixed tlow turbine and ita setting Tranampactions or the Amerieal Society of Civil Engineers 851237bull1)56 1922

27 bull Spannhake W1lhe1Dh Problems or modern pump and tur b1ne design Transactions of the American Society of Mechanical Engineers 56e22$-248 1934bull

28 Sutherlandraquo R A Better ethod or representing and middot tudying water turbine performance ~ansaetions ot thmiddote American Society of Mechanical Engineers 68t675bull 686 1946

29 Teats ot five models or draft tubes tor turbines Engineering News-Record Pbull 182-184 Aug 2 1923

30 White w M American hydztaulic turbines Mechanical Engineering S2t390bull39S 1930bull

31 White w M lhe hydraucGne rega1ner1 its developmentand appl1eat1ons 1n hydroelectric plants Meohanlobulll Engineering 43t37Sbull380 1921 middot

32 Winter I A Economic principlebull in designbull Int Trend in hydraulic urbin practice bull a ampoeiumTranaaot1ona ot the American Society ot Civil Engineerslo6332bull3S2 1941

33 Wiel1cenua G F Fluid mechan1ca or turbo-machineryNev York McGraw-Hill 1947 613 Pbull

APPENDICES

c

Appendix A

NOATIOB

A Angle between the absolute velocity vector and the tangent to the rwmer Subscripts 1 and 2 refel to entrance and exit ot the runner blade

B Angle between the relative 1elooity vector and the tangent to the rwmer Subscripta 1 and 2 refer to entrance and ezit or the runner blade

Angle between the tangent to the runner blade tip and the tangent to the runnel- Subscripts 1 and 2 reter to entrance and exit of the rt1rmer bladebull

Blade angle-gate opening conetant defined by equation (1)

e 09erall efficiency

g Gravitational acceleration assumed constant at 322 teet per second per second bull

H Turbine head detined by equation ($)

m Exit loss coeft1e1ent

Turbine speed expressed in revolutions per minute

Turbine speed under a constant head of 81 teet

specitic apeed of the turbine under a constant head ot 81 teet

p Power output in horsepower ot the tvbine

Power output of the turbine Ulder a constant head ot Sl teet

Pl- Pressure head at entrance to the tUlb1new

l1 Peripheral velocity ot the runneP Subacr1pta 1 and 2 refer to entrance and exit ot the JUnllampr blade

62

v Relative velocity reaulting trom the combination ot the absolute water velocity V and the runner periphshyeral velocity u Subscripts 1 and 2 refer to entrance and exit ot the runner blade

v] Relative velocity vector necessary to produce a tanbull gential entry into the runner blades

V Absolute water velocity Subscripts l and 2 refer to entrano and exit ot the runner blade

v2 Velocity head Subscripts 1 and 4 reter to the ~8 entrance to the turbine and the tail~ace wate~

w Unit weight ot water assumed constant at 624 pounda per cubic toot

V Weight rate ot flow in pounds per aeooncl

XX Velocity component ot ahook See Figule 2

Z Elevation head Subscripts 1 and 4 reter to entrance to the turbine and the taibace water surfacebull

Appendix B ORIGINAL DATA-Run

lfwnber

0-4-1 0-4-2 0-4-3 o-4-4 o-4-S o-4-6 0-4-7 0-4-8 0-4-9o-4-lo o-4-11 o-4-12 0-4-13

o-6-1 o-6-2 06-3 o-6-4o-6middotS o-6-6 o-6-7 o-6-8 0-6-9 o--6-lo o-6-11

Speed

rmiddot2middotbullmiddot(1)

336 38$ 451 S$9 620 669 6lt)$ 120 787 860 932

102imiddot109 bull

352 355 443middot 543middot 620 654AJs32

911 1001 1111

~essure Head rt (2)

410 410 416 426 431 43-7 439 44-9 452 467 482 soo $1 bull $

350 351 35middot7 )66 37-9 37-9 392 41 bull 3 43middot3 460 489

Elevation Bead

fjj $7 $7 $7 $7 $7 $7 51 57 5-15858 $8 58 56 56 $6565656 51 575As5a

Velocit Head

flj 07 07 07 06 06 06 06 os 05 os0404 03

09 09 oa o8 o8 os 07 07 06 o~o

Total Head rt ($)

47middot4 4A44 o 489 49-4 soo $02 $11 $14 $29 5imiddot45 2 576

41 bull $ 416 421 430 44middot3 44middot3 456 47-7 496 523551

Plow

lbtjec

326 324middot317 311 306 30029middot28 middotmiddot middot 386 275middot260 240 218

359 36~35 bull 349 345middot 339 330 318 300 273 240

Line Potential

vyqjbull 1060 1220 ~-0o 1920 2150 2000 2$60 2000 1940 18)015io11 o

1000 1100 139bull5 1760 1925 16$0 1620 1610 1540 1330 870

Line Current

amlscs 960 900 830 740 730655 70bull 0 530 660 600 5imiddot54 6 )60

982 930 860 780 ~3-545

79-5 74-5 670 560 370

P

Appendix B ORIGINAL DATA (Continued)

Run Number

Speed

Pbulltmiddotbullmiddot )

leasure Head ft(2

Elevation Head tt(J)

Velocity He-dfmiddotj

Total Bead tt($

Flow

lbstsec( )

Line Potential vo~ta( )

Line Current

amjs (sect

0bulllt)-1 0-9-2

3ll6 398

28o ~~1

$6 56

1o 10

346 347

390 365

1ooo 1190

aao 835

0-9-3 0-9-4 o-9-S

472 565 632

292 305 312

$6 s6 56

10 o9 o9

)$8 J7~o 37~7

381376 37o

1)6614oo 141o

820 ass ass o-9-6 0-9-7 0-9-8 o-9-9 0middot9-10

680 120 762 844 920

)24337346 366 390

56 $6 56 57 $7

09 os o8 oa 07

)89401 410 431454

367~ 357348 34o 322

1400 1J6o l36o 1310 1170

843 820 7957So 67~0

0-9-ll 0-912

1001 1100

41 bull 7 45-3

s 7 6~0

06 os 480 $18

299 268

980 65$

560 36~5

1-4-1 1-4-21-4-l1-4shy1-4-5 1-4-6 l-4-7 1 4-8 1-4-9 1-4-10 1middot4-ll 1-4bull12

354middot452 562 62q 674shy102 752 760- 863 932

1022 1100-

)82389 4014oa 416 41--7 423 428 44-2 45-7 486 49-2

51S757 51 5-7 5middot15zs sa $8 58 59

07 07 06 06 06 06 06 os o bull o 04 o J

446 45-)46middot4 471 ti7-9480 q86 491505 $19 548 55-4

)28 320 311 306 300 295 291 286 269 2582iimiddot21 bull

1080 14Lo 1550 153-5 1470 141-0 1385 1310 1310 1230 1120 855

970855 875 91-0 94~0 975 966 995 860 77-S 610 4fo

0 ~

Appendix B ORIGINAL DATA (Contirmed)-Run Speed Pressure Elevation Velocity Total Flow Line Line

Number Head Head Head had Potential Current rtjjmbull t~ bttec vyfs am~a12) ( ) ti fli 8

1-6-l $6 33$ $6 0bull9 400 364 1100 93 0 1-6-2 41 34laquo2 $6 oa 406 JS7middot iios a5s l-6-3 500 3~0 5bull6 os 356 1 1 o aos 41middot~1-6~4 35bull4 5-6 oa 41middot 352 16~0 82 0 5~1-6-5 5 bull 36_2 Sbull6 08 42bull6 349middot 161 ~ 0 86~0 1-6-6 622 366 $6 oe 43bull0 345middot 158 0 88~$ 16-A 649bull 37bull1 56 os 43-S 342middot 1570 895 1~- 386 57 07 46-0 192 ) 125A44 333middot 1-6-9 3) 404 5middot1 07 468 317 1620 675 1610 911 42-4 5-7 o6 48-7 298 168 0 61 0 1-6-11 999 451 56 os Sl ll 276 ~2-0 530 1-612 1115 485 58 04 54middot7 238 90 )3 0

1middot9-l 355 279 56 10 )45 385 1040 870 1-9-2 399 28J $6 10 )49 38$ 1140 86 5 l-9-3 ~ ao 291 56 ~0 35middot1 J8J_ JJ6o 815 1bull9-4 579 303 56 09 )68 375middot J4JO 830 l-9bullS 40- 313 )6 09 31middot8 370- 1460 82~0 1-9bull6 679 2) 56 09 3 bull8 364middot 1670 710 l-9-7 682 319 56 o9 384 ) 62 1460 79 5 l-9-8 724 33middot5 56 o8 399 3$6 bull 1480 76 -5 1-9-9 762 34middot3 $6 0 bull 8 407 )48 14910 13middotS 1-9-10 833middot )60 5middot7 os 42$ 339 144$ 686 1-9-ll 926 39middot1 5-7 07 455 318 1290 600 1-9-12 1000 41middot3 0-6 476 298 1115 510$ ~ 1middot9-13 1105 452 s o4 $14 2$6 710 )10

~

Appendix Bt ORIGDIAL J (Continued)

Run Speed Pressure Elevation Velocity Total Plow Line Line Number Head ltead Head jlamp$d P()ten~ibulll Current

r~~~m ft ft lbs~seo voltattj rgj twimiddot t 1 t2gt lt3 ou t ( rt

2-9-1 384 289 S 6 10 35 5 1400 1170 810 2-9-2 443middot 29$ $6 ltimiddot9 360 379middot 11(0 87$ 2-9-J 536 30bull 3 sc 09 )68 374middot 1)40 84 bull) 2-9-4 571 306 $6 09 3~1 372 120bull 0 955 2-9-5 623 316 S6 09 J l )6S UJSo 77$ 2bull9-6 669 327 S6 09 )92 )61 1240 905 2-9bull7 712 )39 56 os 40-3 351 12(0 86 bull0 2-9-8 ~5$~ J48 56 oa 412 348 1290 81 bull ) 2-9-9 04 )63 56 oa 42-7 339 12ltJO 76$ 2middotmiddot9-10 8$2 376 5middot1 07 440 33~- ~ o 710 2-9-11 955 394 5-1 o6 457 300 1100 506 2middot9-12 1000 421 $7 06 48middoti 295 1020 $18 2-9bull13 110~ 463 56 05 $2 267 620 3~0

oshy0

Appendix Gt CALCULATED DAgA

Turbine Run Generator Generator Turbine Turbine Efficiency Turbine Turbine Specit1c

Number OutputKWlt21

Loa~Jes KWlol

Outut K bull (H)

Input RP 12)

middot Percentlt13gt

Speed r~Jmiddot(

0ltput HP ~1

Speed r-m

( 6) middot

o-4-1 0middot4-2 0-4-3 0-4-4 0-4-5 0-4-6 O-qmiddot7o-4-8o-4-9 0-4bull10 0-4-11 o-4-12

1018 1o9a 1220 1)62J40214oa1J4oo 1357 1320 1164 997 718

046 o59 071 092 096 1071oo 134 104 100 109 107

14261sso 17)01948 2008 20322011 1999 19 09 1708 14-84 11o6

281279 27-7 276 215 273271 268 268 26h 258 24-5

soa 555 62$ 705 7)1145 742 74-6714645 51s 45-1

440 sos 585 720 195 sso sao 9$$ 985

1065 1135middot 1230

318 357 319 416 422 419412 39middot9 378 324 260 191

102 12bull4 148 191 21bull 3 22o 233 249 24924middot9 238 221

0-4middot13 418 104 699 228 306 1300 117 18)

o-6-1 982 045 1376 271 $08 496 376 124 o-6-2 o-6-3 G-6-4o-6-5 0-6-6

1023 1200 13 73 J415 139h

051 0middot66 oaa ()bull 96 088

14-39 1696 1958 2026 1986

276 27middot4 273 278 274

$20 61 8 717 7)0726

q95615745 8)5685

390 ll5middot3 sos soo 490

127 170 218 243 2$$

o-6-7 o-6-8 o-6-9o-6-lo

1288 1199 1032 7-45

o9o 094 09$ 096

1846 1733 1511 1128

274 276 271 260

67S 629559 43middot4

980 1085 1165 1245shy

436 )83316 21bull 7

266 276 270 239

0-6-11 322 1oo 566 2141 2JS 1350 101 177 0 --4

Appendix C CALCULATED DAlA ( Continued)-Run

Number Generator Generator

Out2ut Losaes xw LW- 12gt (lO)

Turbine Out2ut

ltPlJ

Turbine Inat lfP Jig)

Etpound1e1ency

PireentDl

Turbine Sed x-~m( 1

Turbine OutEut RPJl)

Turbine Specific

SeeedrIbullntbull

( 6)

o-9middot1 0-9-2 0-9-3 o-lt)-4 09-$ 0bull9-6 0-9-7 0-9-8 0-9-9 0-9-10 o-9-11 0-9-12

aao 994

111$ 1197 1206 1180 11)21081 982 784 5-49 2)9

0middot45oss o6$ 070 07$ 0-77 (l77 or~ o s06o 8 096

123~ 1402 1$80 1698 17bulllS 168$ 16bull18 ~middot5430 1151 a~J4 9

24middotgt24middot3248 25~25 260 260 259 267 266 26middot1 2S2

sos 577 63-7 671 676 650 621 60036J4

327 178

$) 610AlO 3$

92S 980

102$ 1070 1157middot 1230 1300 137Smiddot

44middot4 soo 523 ssomiddot 540so6 46-5 432 368 274 18~8

J46 176 21-1 255 2802s_A 28 289 288 265 231 168

1-4-1 1-4middot2 1-4-3 1-4-4 1-4-5 1-4-6 1-4-7 1-J-8 1-4~9 1-4-10 1-4-11 1-4-12

10bull48 1231 13-S6 1397 1)821375 1))8 1303 1127 953 683) 51

048 067 o7A07 0 bull79 oa1 oss o bullao osa 0lt)0 096 099

J468 1740 1921 1978 1958 19$1 1911 lSSi162 1)98 1045

603

266 264 262 262 261 2512$7 2$6 24middot7 24-3 233 217

551 660 13middot3155 75-6 7~-97 middot4 72$ 67 51middotJ 44middot9 21middot1

475 605 A4220

875middot 910 970_

1000 1090bull 1166 1243 1330

5816

44middot444middot5 430 427 412 392 329 273 188 l0-7

117 101 204 22$ 2)7245 2562sa 257251 222 179

a-C))

Appendix Ct CALCULATED -DATA ( Ocntinued)

1-6middot1 1023 o$2 14-41 26S 505 41~6 26~

54middot5 13middot3l-6-2 1201 067 1boo 625 47-9 17shy~middot41-6bull3 1296 oA9 1 middot43 26 9 700 so5 20bull 4 l-6-4 l3j5 o 0 19~09 268 71bull3 A5o 514 222 1-6-5 1) 5 o81 19(gt4 271 725 51-5 238 l-66 1398 081 198) 27-0 736 8 S13 252~-middot l-6j 1405 083 199i 211 733 885 $middot06 2$9 l-6 13middot9~ 103 2amp 0 279 71 8 985~ 467 ~-69 1228 1 bull 02 17-SS 270 661 109$ 407 ~3~ l-6bull10 1025 100 lSll 26i 573 1175middot 27~S32middot~l-ampu 153 1-00 llft3 26 444 1270 22 24bull8 1bull6-12 294 100 52a 231 22 3 1360 95 172

1-9bull1 904 048 1275 2J4Z $28 S4$ 459 1$2 1-92 98$ oss 13-92 24middot4 57-0 6JO 49bull1 176 1-9middot3 1110 066 1$76 24middot9 63middot4 I2o 536 21-7 l--9-4 1187 072 1685 251 66$ 5 $$ bull 0 261 1middot9-5 llltJ7 1710 25middot4 67-3 93$ 536 28~20-671middot9-6 1186 o 8 1708 25-7 67) 980 $15 2691-9- 1161 oBo 1660 2$middot3 6$6 990 508 29-1 l~- ll-32 oB) 16sect0 2$8 632 1030 471 291 1-9bull9 109$ oa5 2$7 614 1075 29S~middot 0 4imiddot41-9-10 9~91 oas 262 S$1 1150~ 3 o 292 1-9-11 o9o u57 12JiO 21gt 26-77middot74

-45 26sect ~middot91-912 $69 091 sas 25 middot3 1)0$ 196 2J-8 1-9-1) 220 098 426 2)9 178 1390middot 84 16 6

0 0

Appendx C CALCULATED DATA (Continued)

Turbine Run Generator Generator lurbine Turbine Eft1e1eney Turbine lurbine Spee1f1c

Number Output Losses Outit Input Speed Output SPed middot k_-V KW R _ H_bull_P Percent r Thm HP rpm_ (9) tlo) 11) middot (12 _) (lJI ( ) (1$ (14)

2-9-1 9--46 055 1)62 258 528 580 164 2-9-2 1024 056 248 58 4 665 4 9 191iimiddot48 4~middot0 2-9-3 1132 067 05 2$0 641 795 52q 237 2-9-4 1148 065 1027 2$1 -~8 845 525 252 2-9-5 11 77 oso 16-83 253 6 910~ 522 270 2-9 6 1122 071 1600 251 622 960 47-5 2722-9-A 1092 015 1562 257 608 1010 445 2z12bull9- 1052 079 1514 261 580 1060 41middot7 2 2 2middot9-9 986 o82 ]429 26) 542 1105 372 277 2-9-10 915 086 1340 268 500 1160 334 27-6 2-9-11 638 087 972 254 )81 1270~ 229 250 2-9-12 )28 090 828 259 )19 1295 179 226 2-9-13 192 094 383 2$ 6 150 1370 7 3 152

-3 0

Page 3: The Effect of A Variable Draft Tube Flow Area on the

or the many persona who have shown interest and

offered assistance in the progress or this investigation

certain ones merit special acknowledgment

In particular gratitude is expreased toward H G

Barnett Head or the Depaltment of Electrical Engineering

L N Stone Associate Professor of Electrical Engineering

and w H Paul Profeasoll of Automotive Engineering tor

their generous supply ot advice and equipment J R H Shoebull

maker Jr Assistant Professor of Civil Eng1neering for

his help and photographic work G w Holcomb Chairman or the Department of Oivil Engineering and w c Weatgarth

Assistant Professor of 01vil Engineering for thea

cooperation and assistance in obtaining material and

auppllea J Thomas B Hayes and Vtetor N Bredbullhoett ot the

oonaulting engineering firm or Cornell Howland Raybullbull and

Merryfield for their suggestions and encouragementJ H D

Pritchett tor the photoglaph1c duplication B K Scoggan

R D Smith D D Sweeney R M Elder R L Polv1 and

W H Knuth ror their b1releaa ettorts in the taking ot

data and Mra Jeanne Nepoundf for her patience in t he typing

ot the final draft ot the thesis

lb1a investigation could have been neither started

nor finished without the inapirat1on1 ideas and criticisms

of Fl-ed Merryfield Professor ot Sanitary Engineering to

whom a special debt is owed

Grant Robley Aas1stant Dean or t he School of Engibull

neering or Yal Un1ver ity ia the cause or it all

Arl1sa D Ray

bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull

bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull

bull bull bull bull

bull bull bull bull bull bull bull bull bull bull

bull bull bull bull bull bull bull bull bull bull bull bull bull

TABLE Qf CONTENTS

Chapter

I INTRODUCTION bull

A Purpose and Scope of Investigation bull bull bull bull l B Reaction Turbinea bull bull bull bull bull bull bull bull bull bull bull bull 2 C Draft Tubes bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull 5

II DISCUSSION OF TURBI NE LOSSES bull bull bull bull bull bull bull bull 1

A General bull a Shock Loae ~ c Exit Loss 12

III PROPOSAL OF ALTERNATE METHOD OF CONTROL bull bull bull bullbull 14 A Type and Location of Control bull bull bull bull bull bull bull B Estimated Eftect on Actual Turbine bull bull bull bull ~ c Requirements tor Teet Verification bull bull bull bull 19

IV APPARATUS AND METHODS OP TESl bull bull bull bull bull bull bull bull bull 23

A Equipment bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull 23 B InatlWilentation and Measuring Devicbullbull bull bull 26 c Operational Pz-ocedure bull bull bull bull bull bull bull bull bull bull 26 D Schedule ot Rune bull bull bull bull bull bull bull bull bull bull bull bull bull JS

v DATA bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull 37

A Original Data bull bull bull bull bull bull bull bull bull bull B Calculated Data bull bull bull bull bull bull bull bull bull bull bull bull bull ~A

VI TEST RESULTS bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull 44 A Presentation of Results bull bull bull bull bull bull bull bull bull 44B Discussion of aeaults $1

VII CONCLUSIONS bull middot 56bull bull bull bull bull bull bull bull bull bull bull BIBLIOGRAPY bull bull bull bull bull bull bull bull bull bull bull 51 APPENDICES bull bull bull bull bull bull bull bull bull bull bull 60

A lfotation bull bull bull bull 61 B Original Data bull bull bull bull bull bull bull bull bull bull bull bull bull bull 6)c Calculated Data bull bull bull bull bull bull bull bull bull bull bull 67

bull bull bull bull bull bull bull bull bull bull bull

bull bull

bull bull

LIS~ OP_ __ ILLUSTRAfiOBS-middot

Fiere Page

1 13 $ Inch Reaction turbine bull bull bull bull bull bull bull bull bull bull 4

s bull bull bull bull bull bull bull bull bull bull bull bull

Plow Area bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull 4S

2 Turbine Runner Vector D1agrama and Shook Loaa Diaptama bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull 10

) Turbine PertoPmance CurYea bull bull bull bull bull bull bull bull bull bull 20

4 General View ot Teat Equipment bull bull bull bull bull bull bull 21

6 View ot Teat ut-bine bull bull bullmiddot bull bull bull bull bull bull bull bull bull 7 Teat Generator and Platform bull bull bull bull bull bull bull bull bull 27

8 Iutrument Board and Field Rheostat bull bull bull bull bull 27

9 Vlev ot Water lUteoatat bull bull bull bull bull bull bull bull bull bull 29

10 View or Water Rheostat bull 29

11 Vater Plow Diagram and Electrical Laout bull bull bull 30

12 Sketoh ot Draft ltlbe and Teat Inaerta bullbull bull bull 33

13 View ot Dratt Ube Inaer bull bull bull bull bull bull bull bull bull bull 34

14 Vlev ot Dr~t lube Iuert bull bull bull bull bull bull bull bull bull 34 lS Curves ot Generator Voltage Drop and Copper

Lose bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull 40 16 euvtee of Oenerator Stray Power Lobullbull bull bull bull 41 17 Turbine Charae ter1at1ca with lOOC Dl-att lUbe

18 Turbine Characteristicbull With 7SC Draft tube Flow Area bull bull bull bull bull bull bull bull bull bull bullbull bull bullbull 46

19 Comparleon Between 7S~ and 100 Pratt Tubbull Flow Areas ot Power and Etf1c1ency at OVer Gate Condition bull bull bullbullbull bull bullbullbullbullbullbull 47

bull bull

~ Q ILLt1SlATlOIS (Continued)

F1pe

20 Comparison Between 15 and 100~ Draft Tube Flow Areas of PoweP and Ett1c1enoy at Halt Gate Condition bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull 46

21 Oompu1aon Betwen S~ and 100~ Draft Tube Flow ANaa ot Po-r and Efflctency ab Ovbullbull Gate Condftimiddoton bull - bull bull bull bull - bull bull middot bull bull bull 49 Compar1aon ot Spec1tic Speeda tor 75~ middotand 10~ Draft Tube Flow Areae bull bull bull bull bull bull bull bull so

I

bull

filE EPPEOI OF A VARIABLE DRAFT TUBE FLOW AREA

ON THE PERFORMANltJE OF A REAOTIO TURBINE

Chapter l

IITRODUClIOH

A hrpose and Scope of Invst1pt1on

Present day control of reaction turbines is accombull

pl1ahed by the use of wicket gates immediately- preceding

the turbine runner These gates otter an interrelated conbull

- trol to the quantity and direction ot the water entering

t-he runner ie a change in the amount ot flow will rebull

middot ult in a change in direction This combined control leada

to loesee at all but the rated or design condition ot the

turbine (2$ Pbull )71)

This investigation dealt with an att mpt to better

turbine performance at all points of operation b y the

eatabliahment of separate controls over the rate of flow

and the d1J~ect1on ot the entering watebullbull

The only physical modification of the test tlutbine

was the insertion of flow restricting device in the dratt

tube

Ot primary interest were the trends in the change of

2

turbine performance with the amount ot draft tube tlow

area To this end complete turbine charaeteristiea were

not obtained tor 0ach device inserted in the draft tube

It was considered sutt1e1ent to obtain data tor the tull

speed range tor two representative gat openings one

greater and one less than the rated gate openingbull

Before proceeding with th report ot this 1nvest1gabull

t1on it 1a desirable to supply sa b ckground m terial

on reaction tw-blnes and their dratt tubes

B Raot1on 1rbinea

A hydraulic turbine is a device for converting the

energy in water to eohanical energy (6 Pbull 93lbull96S) furbull

b1nes may be loosely grouped into one of three elasse

impulsmiddote 1 reaot1on or propeller

An impulse turbine normally operates under a high head

and with a relatively sma~l amount ot watel in the converbull

sion or kinetic nergy to mechanical energy The propeller

turbine utilizes pressure energy to develop mechanical

energy while under a low head and p ss1ng a large amount of

waver

The reaction turbine lies somewhere between these two

extremes It changes both pressure and kinetic energy

while oper ting under a medium head with a moderate ount

opound water An example or a reaction turbine is pietur d in

Figure 1

lhe terms of high low small and so tomiddotrth are only

relative in sense A turbinebulls class1f1 eat1on is depenfent

upon its hoad rate of diacharge and speed of rot tion A

useful index tor turbine comparison (5 Pbull 825) is termed

specific speed and this ia a function of the rated ipeed

power output and head or the turbine The common range in

values ot speoitic speed ($ Pbull 826 ) tor each type ot tlirshy

bine is

Impulse J to SS tor one nozzle)Reaction bull 22 to 80 Propeller - 85 to 170

The development of t he reaction turbine began in the

early part or the nineteenth century (26 Pbull 1217bull1)6)

The trst efficient inward tlow turbine was de igned by

James B Francis an American in 1649bull For many years

turbine design was a matter of cutbullandbulltry in America an4

pure mathematical analysis 1n Europe It was not until the

two schools began exchanging ideas in the l$tter halt ot

the n1neteenth century that pronounced advancement was made

in the field

ObTioual7 the primary pux-pose ot any turbine inatallabull

t1on is t he production of power Added to this is the

restriction that the production or power must necessarily

be a controlled process An example of this is where the

turbine is direct-connected to an electric generator which

4

Figure 1 - 135 Inch Reaction Turbine

5

must operate at a constant speed or rotation even though _

the power demand ohangos In thiamp case the turbine nuet

be eap~able or producing a range of power output yet menshy

ta1n e eonetant speed

Speed regulation of the turbine iv accomplished by

means ot a governor (23 Pbull 24bull3-7) bull The contr-ol or regulashy

tion 1s indirect that i s the governor actually exereiaabull

control over the water in order to JJaintain e given speed

Co-ntrol over- the turbine end bence its speed and

power is the function ot a ring of movable wicket gates

located just upsttteam of the turbine runner These w1eket

gates 1n the process of opening and closing upon eeeh

0~1ar in a rotational manner actually control the amount

velocity and direction of tne water passing throu~~ them

C Draft Tubes

It has been found that the effeetive head on a reae

1l1on middotturbine is increased with the addi timiddoton of a draft tube

(3 Pbull 256bull264) Tne draft tube does thin by~

(1) Making a greater presaure d~op across the turbine

possible by the creation of a negative pressure at the

discharge or the runner and

2) DeoreaGing the k1net1e energy lost by increasing

the eross sectional area at exit

he draft tube permits the turbine runner to be

6

located above the tail race water surface without the

sacrifice of head However cavitation will cause pitting

of the turbine if the difference in elevation is too great

A common maximum elevation difference is 19 feet although

this figure is quite subject to modification between difshy

ferent installations (3 p middot 264-266)

There are many different types or draft tubes in use

today the choice or type being largely a matter or

economics (2$ p 368-370) A very common type particushy

larly among the smaller units is vertical with flaring

sides However the angle of flare is limited by the possishy

bility of separation of the flow from the sides In order

to achieve a certain discharge area the length of the tube

may be such as to require a great deal of excavation In

oases or this sort the cost of this excavation must be

balanced against a more elaborate design that does not

require as much excavation Other draft tubes in use

include the elbow hydracone and spreader types

Despite the differences found in construction and

design the draft tube must accomplish the desired objecshy

tives while offering a good hydraulic geometry to the flow

passing through it An inefficient draft tube defeats its

own purpose

Ohapter II

DISCUSSION ~ TURBINE LOSSES

A General

lhe head that 1a actually utilized by the turbine 1a

less than the effective bead as defined by equation ($) by

the amount that 1a lost due to mechanical and hydraulic

reasons

Mechanical loaaea are a function or the turbine 8p$ed

fhis ia not a lineaz- function but varies eomewhere between

N and N2 (3- Pbull 224)

Hydraulic losses encounteled in turbines ma- be subshy

divided aa to the location or occurrence (3 p 225-227) aa

fOllOW$S

(1) Penstock and scroll case

(2) Wicket gates

(3) Between wicket gates and turbine runner

(4) Runner passages

(5) Runner exit into draft tube

(6) Draft tube and

(7) At exit from the draft tube

The flow in the penstock scroll case wicket gates

runner passages and draft tube may be envisioned as

examples of flew in conventional pipes elbows and convergbull

1ng passages If this comparison may be made it could be

assumed that the losses encountered in these locations

would be proportional to vn ~ value ot N is normally2g

aesU111ed to be 2

he losses encountered between the wicket gates an4

the turbine runner and exit lossos are special cases which

will be discussed separately

B Shock toes_

The flow betwe n the wicket gat outlet and the runner

blade entrance is or particular 1nt rest because no direct

comparison vith common flow situations is obvious

Conaider the vector diagram (7 Pbull 7576) in Figure 2

The veetoo v1 is the absolute entering velocity of the

water and is fixed in magnitude and direction by the setbull

ting or the wicket gates The vector l11 1e the peripheztal

velocity of the runnel which tol any given turbine 1e

dependent only upon the turbine rotational speed The

combination of these two vectors ylelda the third vector

v1 which is the relative entering velocity ot the water

nere is only one setting ot the wicket gates for a

given turbine a peed that will produce an angle B1 which

coincides with the blade angle B1bull At other gate settings

the vector v1 will rotate and change in magnitude in such a

9

t ehion that B1 will beoome either greater or 1 sa than B1bull Th1 give rise to tbe phenomenon term d shock loasft

If B1 1a greater than B1 the relative ent ring veloebull

ityt v1 will have a compon~nt opposing the forward motion

of the runner The shock loss could be typified bullbull that

occasioned by direct impact or the water 0n the blade- If

E1 is lese than a] the vector l will overshoot the blade

and the flow will tend to eddy around the forward portion

or the blade tip

The shock loss can then be either due to impact or

eddying flow Since the area norm 1 to the radius at outlampt

of the w1eket gftee is essentially equ 1 to the area normnl

to the rad1u~ at the inlet to the turbine runner the combull

ponents ot vl and vl perpendicular to ul will b approxishy

mately equal This leads to the conclusion that xxbull ~epresenting the shock vector 1 parallel to Ulbull

For either the impact or eddy case the trigonometric

law of $1nee leads tot

XX

bull ul - sin (Bi-Al) vl eln Bi

It it 1a assumed that the energy lost in the shock 1a

the Telocity head ot the shock component XX then

10

VELOCITY VECTOR DIAGIWI

TYPES OF SHOCK LOSS

xbull X

IMPACT BDDJ

XX 1a Teloc1t7 caponent ot shock

Figure 2 - ~bine Runner Vector Diagram$ and Shock Loss Diagrams

11

2 shock loss (XX gt2g

C =sin (BimiddotAl)Let (1)sin Bi

(UlmiddotCV1)2Then shock loabull (2)- 2g

For a given gate opening C ia a constant ranging

from about 14 to 10 For a well designed wheel it is to middot

be expected that C would be approximately equal to U1V1

at rated conditions ie at point of maximum efficiency

This point will occur in the neighborhood of 3~ to 78

gate opening for moat turbines For overgate conditions

the angle A1 becomes larger so the value of C would

decrease For gate openings below rated conditions t he

angle A1 decreases and C would decrease One could expect

a fairly uniform decrease in t he value of C as the gate is

closed from t he overgate position

The velocity v1 is approximately constant for any

turbine speed since the area and rate of flow both decrease

fairly uniformly However for a given gate opening the

velocity V1 will decrease with increased turbine speed

From the foregoing comments and equation (2) the

following trends can be established

(1) For constant turbine speed the shook loss curve

will be close to parabolic in shape concave upward and

have its maximum near t he point of complete gate closure

--

12

and its minimum near the rated gate position

(2) For conatant gate opening the shook loss curve

will approximate a symmetrical parabola with its vertex

the point of minimum loas located at the rated condition

of operation (7 Pbull 79)

c Exit Loas

It can be seen from Figure 2 that the exit loss from

the turbine would be v222g if no draft tube were present

The addition of a draft tube permits the gradual reduction

of velocity by an increase in cross sectional area between

the exit of the runner and the exit from the draft tube

The exit loss and the frictional loss encountered in

the draft tube may be placed together in the expression

m va2 (3)Exit Loss ~---2g

For the ideal case of no friction in the draft tube

m is equal to the square of the ratio of the area at exit

from the runner to the area at exit from the draft tube

In an actual turbine installation however friction

will change the value of m (7 p 84-85) to somewhere

between that for the ideal case and a maximum ot 10

In the interest of maintaining a minimum exit loss

the turbine should be designed and operated so the velocity

V2 will be minimum This will occur when the discharge

13

vector is at right angles to the tangent to the runnerbull

ie the angle A2 1e ninety degree bull It ia to be expected

that this condition will be tultilled near the design con~

d1t1ons ot the ~bine

Current design praetiee 1 to have a small component

ot v2 in th$ direction of turbine rotation at rated condibull

tion$ ltS p 938)

For a constant turbine speed the d1seharg or exit

loss is ess nti lly a constant

For a constant gate opening the exit lo s curve is

aptrroximately a symmetrical pa~abola with ita vert x the

point or minimum loss located at a slightly lowe~ speed

th n the turbine rated speed (7 Pbull 79)

Chapter III

PROPOSAL OP ALlERMAlE MFTBO 0 CO TROL-A lz ~ Location 2 Control

Thua tar only practice and theoretical aspects appemiddotrbull

taining to present day turbinea have been d1acuaaed It

haa been presented that control over the ~bine ia ezerbull

oiaed b y manipulation of the wicket gatea located 11101led1bull

ately preceding the runner These gate - upon rotation

modify both the magn1tu4e and the direction ot the entering

velocit7 Moreover it has be n shown that a simultaneous

change in these two variables leads to inefficient operabull

tion by the introduction of shock loss he farther the

point of operation a from the rated conditione the more

aerioua ia the ahock loss encountered

Any attempt to better turbine pertorance at other

than rated conditione and tbne flatten the top ot the

etticieney hill8 must concentrate upon the lessening ot

the ahock loaa It 1a a aumed that 1 provement in the

scroll case gates and runners would lequ1re sueh pertecbull

tion 1n machine work and metal$ as to be prohibitively

expensive

It ie surmised that any move to elblinate eYen parbull

tially the shock loss would require separate control ovel

l$

the flow and gate exit angle Since it is improbable that

d1~ect1on could be controlled at any location other than

where the gatea are situated in current turbines it will

be assumed that guide vanes will be necessary regardlesa or the method used to control the rate of flow

The primary purpose ot th se guide vanes 1s that or control over the direction ot the incoming water They

should be free to rotate in much the same manner as ordibull

nary wicket gates in order to exercise control over th

turbine speed

If the rate ot tlov is to be controlled elsewhere it

must be modified either in the penstock or the draft tube

Devices that could be used are standard valves gates

variable orifices variable venturi sections and associated

flow regulating schemes

Alauming it were decided to locate such a device upbull

stream of the turbine it would be necessary to allow disbull

tance tor the flow picture to become reestablished prior to

entry to the turbine A contused flow making transit of

the turbine passages would only contribute additional loesbull

ea Such a distance allowance would be perbapa 20 to So

diameters (2$ Pbull 119-123) In large penstocka th1a would

repreaent a considerable distance Which from the viewbull

points ot convenience and control would be undesirable

Attempts to ascertain the effect or additional tlov

16

reduc ion at the wicket gatctsmiddot wae ade 1n the lfadraulioe middot

Laboratory of Oregon St middot te College in 1933 (20) Three

d1tterent thode ot reducins the tlow were t~ied

(l) Locking in the cloeed position pairs or wicket

gatea located opposite to eaeh o~er on the -periphery ot

the wheel

(2) Locking adjacent gates in an open position by

inserting blocks of wood between them and

()) Suocess1vely looking adjacent gates in the closed

position

The results indicated a arked reduction in both power

and efficiency when compared to the curves tor normal gate

operation However it was demonstrated that it was poae1bull

ble to ahitt the power and tfieiency curve ill relation to

turbine apeed lbis important feature will be diacussed

later

ihe main conclusion of the investigation was that conbull

trol by the conyent1onal wick t gates was auper1or to other

methode egtt control exercised at the gates the aelvebullbull

It would app$ar that the bebullt location tor flow conshy

trol would be in the draft tube since none of the objecbull

tiona prev1ously mentioned wou~d eziat there

As bas been stated previously the sole object or the

17

18

turbine is to produce power as etfic1ently as possible

The equation tor the power output of a turbine () Pbull 227)

PaWHe HP (4)55o bull bull Assuming the head 1a constant and a g te located in

the draft tube decreases bhe rate ot flow the power eu

only be increased if the etticiency increases

The ettective head Gn the turbine 1s conventionally

d r1ned as the difference between the auma ot the elevashy

tion head pressure head and velocity head at the entrance

to the turbine casing and the tailrace ($ Pbull 872)

lt ie recognized that the theoretical treatment ot

shock loss as given is highly approximate and serves only

to dictate certain trenda For example the area at xit

rom the wicket g tea CfUl be measuPed with some exactness

but there exists no guarantee that the wateP particles will

complet-ely fill the apace oz- will exit at the establiahed

g te angle The same can be said of the exit trom the

runner blades AssUIlptiona were implied which would indishy

cate that all water particles passing a given croea section

ampH traveling at the same velocity in the same direction

the e alone are autt1c1ent to show 11m1tationa in a theoretbull

1eal approach to the problem

Assume a turbine with ordinary wicket gates tor oonbull

trol compared gainst the same turbine with a gate in the

18

draft tttbe tor supplampment1ng control or the rate ot rlow

Let it also be assumed that the two turbines are opershy

ating at the same point It 1s desirable to predict relabull

tive performance of the two turbines 1 this point of

operation is such that edd7 s hook loss ot reasonable proshy

portions is present in the fir t turbine

~ tull erteot of the shock loss will be exper1 need

by- the fir t turbine

lhe second turbine will derive certain advantages 11

the gate in the draft tube is adjusted to reduce the tlov

1n the proper amount Since they vary a the square ot

the veloo1t7bull the lossabull in the aeroll case wiomiddotket gate

and runner passages will decx-ease aetet-r1ng to Figure 2 1

it can be seen that a decreased velocity v1 w-ill reduce the

eddy shock losa

The ent loss in the dJtaft tube of the second turbine

will be the sum ot the tr1ct1onal loss and the velocity

head at ex1t The velocity head dissipated will be greater

due to the closing action or the gate but the reduoed

t~ictional loss which ia a tunction ot the rate of tlow1

will partially balance this

It 1a entirely possible that the net reduction in

losses in the second turbine will lead to a greater ettibull

oiency and more power output than 4eYeloped by the first

turbine

19

In Figure 3 the plot ot power output against turbine

speed for Curv A~ represents the typical family of curvea

tor a reaction turbine Th b st sp ed is the locus ot

points connecting maximum eft1oiency at each gate opening

The operating speed is the coZUJtant turbine apeed which

passes through the point ot maximum efC1ciencr of the turbull

bine The plot of turbine efficiency against power output

for Curve A is also ahown

It the turbine with flow regulation in the dratt tube

oan demonstrate superior power and efficiency at part loads

the effect would be the same as a shifting or the power

curves toward the condition shown fop Curve B 11 Thisbull

illustrates th ultimate case of the uperpoait1on of best

and operating speeds It will be noted that the pet-form~

of the turbine ot Ourve Bu 1a better than that of CUrve

A at part loads because of ita ability to sustain a relabull

tively high etticienoy ovel a Wider range of power output

o Reguireaegts tort Test Velitication

It is desired to deterra1ne the effect on the turbine

performance b) the addition of a gate in the dratt tube

Th step in the teit will bet

(1 To determine the power output and efficiency ot

the turbine tor wicket gate settings above and below rated

conditione for a wide range ot speed

20

CURVEAbull

TURBINE SPSBD TURBID SPEKD

POIBR OOTPOl

Figure 3 - Turbine Performance Curves

21

22

(2 peat (l) with the gate installed in the drat

tube

(3) middot Converting middot all data to a constant head compare the

powere and effioiencies at the same wicket gate setting and

turbin speed tor the two cbullses

If the ddition or the gate indicates an improvement

in power output and efficiency and the powe~ curve shifts

to the right along the turbine apeed scale the advantage

ot draft tube con~ol of the flow will hav been demonshy

strated

Chapter IV

A E9J11pment

ih turbine used in this test is lJ 5 1nch Pelton

reaction turbine with a rated output ot 30 horsepower under

a head of 56 feet at a speed ot 720 reYolutiona per minute

Views of this turbine are hovn in Figures S and 6 The

turbine is installed on a concrete pad located over an open

channel in the Hydraulics Laboratory at Oregon State Colshy

lege The date of manufacture of this turbine was 1915

The water was delivered to the turbine from a sump

reservoir by two pumps operating 1n parallel Each pump 1a

an 8 inch Pelton double suction centrifugal pump witb a

rating of l$00 gallons per minute at a head ot 75 teet with

a speed ot 1175 revolutions per minute Tbe inlet tlange

ot tne turbine is $pprox1mately 18 feet above the center

line of the pump

A direct current generator was coupled to the turbine

to receive tne power d veloped as shown in Figures 4 and 7 The generator is a Spr gue Electrodynamometer rated at SS horsepower with a speed range of 7$0 to l$00 revolut1one

per minute The classification is type LO 26A 2)0 volta

Figure 5 - View of Test Turbine

Figure 6 ~ View of Test Turbine

and 149 amperes lbe generator ti ld was aepar tely

excited using direct current from a motor g n r tor ampt

(l$ p 4~8)

The power output of the generator waa dissipated in

the water rheostat (3 p 488-489) shown in Figures 9 and

10 The galvanized tank contain d water ot variable d pth

on an electrode ot cast iron m aauring 1bull x 1 x 1

In the initial installation of the turbine it was

intended that the power output should be measured with a

Prony brak bull For th purpoa68 or this teat it was decided

that the brake was too instable and the generator was

substituted The platform for raising the generator the

nee asary two teet for alignment was built out of available

material In this case heavy laminated wood blocks reiashy

torced with other timbers were used and bolted through the

concrete deck (11 Pbull 36-$7)

Due to the light concrete deck the lack ot mas in

the platform and the slight misalignment in the flexible

coupling ao e vibration waa encountered It seemed to

ncr aae linearly to a maximum at the speed of bout 750

revolutions per minute Above this speed no vibPation was

noticeable The vibration waa not se~ere and does not

appear to have materially affected the test results

26

B Intrumentat1on ~ eaeur1ng Devices

The pressure head at inlet to the turbine vaa meaave4

bymeane ot two )6 inch waterbullmeroury manometerbull connected

in series as shown in Figure 8

The terminal voltage ot the generator vas meaeured by

a laboratory voltDleter with a range to )00 yolta and callbull

brated to within 15 Yolta

The armature current bull and hence the line current was

measured by a laboratory ammeter with a range to 150 amperea

and callbrated to w1 thin o 7S amperes

Tae rate ot tlow was established by weight and time

meaeurementa The weighing ank has a capacity ot 121 000

poundsJ the weight belng indicated by Toledo direct reading

scales Timing was done with a hand atop watch with clivibull

aion ot 02 second

he ~ater level in the tailrace was dete~1ned by a

hook gauge lhie was read to the nearest 001 toot

The turbine and generator speeds were eaaured by a

hand tachometer The technique of almost cont1nuoua readbull

ings of the speed gave an error ot no more than 5 revolubull

tiona per minute

c Operational Procedure

Atter the water level in the aump was checked to

insure an adequate auppl7 the puapa were primed and

27

Figure 7 - Test Generator and Plattorm

Figure middot8- Instrument Board and Field Rheostat

28

started After venting they were valved for operation 1n

parallel

The motor generator set was started to supply the

field current and the circuit breaker was closed Water

wa added to the water rheostat to the level shown in

Figure 10 ~ field current wae minimized by cutting in

all the f ield resistance in the field rheostat of Figure 8

The l2 inch gate valve shown in Figures 5 and 6 waa

slowly opened and the turbine and generator brought up to

speed The 12 inch gat valve and turbine were vented and

the pumps were checked to insure neither had lost ita prime

lhe water rheostat offers very steady load 1f the

water level is essentially constant and the water temperabull

ture 1a fixed () p 488~89) In order to maintain this

constant temperature it was decided not to circulate the

water in the rheostat but rather to allow the water to

boil thua achieving the desired result A standing wave

was set up on the face ot the electrode by the boiling

action but a atable load was eatablished except at very

low water leYels where th11 agitation led to fluctuationa

in the line current

After putting the turbine and generator on the line

maximum power was dissipated in the rheostat by redueing

the turbine speed to between oSO and Soo revolutions per

minute Salt vas added to the rheoetat wat r to increasemiddot

29

Figure 9 - View of Water Rheostat

Figure 10 - View of Water Rheostat

Separate Field ExcitationFrom Motor-Generator set Compound Water-Mercury

---shy

re Manometer

I Q)

~ 0

~

Book Gauge

Open Channel

I

Slap Reservoir

Figure 11 - Wat~r Flow Diagram and Electrical Layout

31

waiting pe~iod ot perhaps an h~ followed

while the boiling point or the water wbulls reacbe4 During

this ti+ne the manometer was vented end eheoked electrical

measur1ng 1nstlUments were connected end the hook gauge was

adjusted tor elevation

It required about two- houtte tor the generator to reach

its normal operating tempe-ratu~e_ After the water in the

rheostat and generator had reached their operating temperabull

turea it was possible to begin the taking of data

The only vaPiable which was controlled wee the turbineshy

generator speed However the upper l1ut1t of safe line

current was slightly over 100 ampJilPampPes and the eireuit

breaker would open when the current reached lOS ~ere bull

Control was exercised by means ot regulating the water

level and salt 1n the water rheo tat and the res1stsnoe of

the tield rheost t~

The etfeet ot each type ot regulation on the three

variables is shown below

Volta Aaperebull Speed

Inc Dec Inc Dee~ Inc Dec

Wa~e1 Level Inc Dec~ X

X X X X

X

Salt Concentration

Inc Dec X

X X X X

X

field Resistance

Inc Dec

X X

X X

X X

32

Jlot all methods gave the ame amount ot change in a

given variable and a period of experiment and trial led to

the following scheme starting the rune with the lowest

turbine speed the water level was high with a high amount

ot salt and the field resistance was cut completely out

Aa it became necessary to increase the speed tor each

aucceasive run either cutting in t he field resistance

decreasing the salt concentration or lowering the Vater

level would produce the desired result However decreasbull

1ng the salt concentration had to be done Without a net

gain in water which led to a tluahing procedure that was

not particularly good because cold water was introduced

which required time to heat to the boiling point Cutting

1n additional field resistance was a good method but th1a

increased the amperage possibly to the point of opening

the circuit breaker Lowering the water level was aatiashy

factol1 until the level got too low causing the current

fluctuation previously mentioned Actually it turned out

that a combination of lowering the water level and cutting

field resistance in would carry the speed from ita minimum

to 1ts maximum value it the proper choice were made each

time the speed waa to be changed At the conclusion of

each aet of runs at a high speed the water level would be

low and the field resistance high

33

TURBINE

PAD AND DECK

TAILRACE

WATER SURFACamp

CONCRETE

DRAFT TU1B INSERTS

7 5( DRAFr TUBE

FLltJI ARIA

5~ DRAFT TUBE

FLOI ARSA

Figure 12 - Sketch of Draft Tube and Test Inserts

34

Figure 13 - View of Draft Tube Insert

Figure 14 - View of Draft Tube Insert

D c __ ~s_middot hedu_le of

A number was assigned to each run The fi~st number

applies to the draft tube tlow areas

1 bull 100~ flow area or 0~ oonatriction

2 - 7S tlow area or 2$ conatr1ct1on

3 SoC flow area or so~ constriction

The second number refers to the wicket gate openings

9 over gate opening

6 bull intermediate gate opening

4 bull one h lt gate opening

The third number 14entif1ea the location of the particular

1Wl in a set ot rona made at a given dratt tube tlow area

and wicket gate opening

fnua run number 1bull4bull10 would identity this as the

tenth run ot a set made at halt gate with 75 ot the draft

tube t1ow area

Rune w re made tor a g1yen dratt tube condition

Firat tor tull 41-aft tube flow area seta ot rune were

made for the overgate halt gate and intermediate gate

conditione An insert was placed in t he draft tube and

rune based on the same gate conditions were made tor the

7S~ draft tube flow area case The insert was then changed

to allow only $~ draft tube flow area

The inserts are sketched 1n Figure 12 and photographed

ln Flgurea 13 and 14 They oonaisted of circula~ segments

36

or l2 ineh plywood mount 4 on wooden legs 10 inches high

The 1nse7te were placed in position and secured by th use

ot a-clamps on the legs and the outside ot the bottom of

the draft tube The obvious disadvantage to this method

waa the neoeasity tor draining the water from the tailrace

tor a change ot 1naert The advantage vas of course the

simplicity ot design and construction

Chapter V

DATA-A Original Data

The normal data-taking crew consisted or two men

Assuming adjustments having been made to secure a certain

turbine speed (aee section on Operational Procedure) one

man would take semi-continuous speed readings with the hand

tachometer until a state or rotational equilibrium was

reached This could be only a period or two minutes up to

ten or tifteen minutes As soon as steady speed was

assured the data taking would begin The second man went

to the weighing tank Where a minimum ot three weighingamp

were made The requirement was to get three consecutive

readings such that the ditterence between tbe smallest and

largest time did not exceed 04 seconds The time to

collect a given weight ot water was then assumed to be the

arithmetic average of the three times He then went to the

hook gauge determined the hook elevation and then

recorded the data on the data sheets The first man meanshy

while had taken readings of the line voltage line current

and manometers and checked the turbine speed by multiple

readings During the length of the run all values were

38

checked to determine mean values for recording

The minimum length of one run was about five minutes

If one or more measure ants tended to drift during the run

all values wer discarded and a new run began as soon aa

qu111br1um was stabl1shedo

B -0-al_e_u_l_a_t--d Data

The h d on the tu~bine 1 defined by

($)

The maxtmwm velocity V4 was equal to about o8 tampet per

secon4 which makes it a negligible quantity when converted

into velocity head

An engineerbulla level was used to deterine the d1ffePshy

ence 1n elevation between the compound water-mercury manoshy

meter and the hook gauge Using this value the equation

for turbine bead becomes

where z4 is the hook gauge reading

The rate of flow 1 cent

w weight or water collected average time to collect

The inlet velocity v1 vas calculated by dividing the

weight rate or flow by the specific weight of water and the

)9

area ot ~e inlet pipe This was equivalent to dividing

the weight rate of flow by 490 Then the power input to the turbine is equal to

WHpin rri

10 (6)

Also

(P ~ut) Turbine

(P out) + Generator

(P lost) Generator

The power output of the generator is simplJ the

produot ot the terminal voltage and the armature (line)

curPent The power lost in the generator can be subdivided

into copper losses and stray power losses lo evaluate

these cunes based on losses of an identical generator

11leampsured by the Department ot Mechanical Engineering were

used The loss curves are reppoduced in part in Figures

15 and 16

Determination ot generator losses proceeds as tollowau

(1) From Figure 15 detem1ne the vo1tage drop in the

armature circuit using the temperatures of 1220 F and the

meaaured current

(2) The induced voltage is t~e sum of the terminal

voltage and the voltage drop 1n the armature circuit

() Entering the induced voltage and the turbine speed

into Figure 16 the stray power loss can be determined

(4) The copper lose can be evaluated from Figure 1$

using the measured current and the temperatlll-e of 1220 P

40

25 ~------~--------~--------~------~

U) -U) - 20

f-4 ~

-~ -gt 0

0

VOLTAGE DROP

~ - i -

- bullbullbull bull - -middot-middot -+ ~- + -t--+ ~ - ~ middotbull ~-~ middott- -+----- _ -4 middotmiddot- --~-+-t---r~~ ~--+t-t- - ---t-c-++~-ulf--

0 50 75 100

Figure 15 - Curves of Generator Voltage Drop and Copper Loss

41

1200

1000

800

600

800

0

0

~-

middot--~ 1shy --1 + bull l

100

I -

150 200

IIDOOED VOLTAGB (VOLTS)

Figure 16 - Curves of Generator Stray Power Loss

_ j

-bullshy -L---- shy middot -shy

250

- r

42

(5) The generator los os equal the sum of the eopp r

loss and stray power loss

~e efficiency or the turbine is taken as

etticiency u e =P out (8)Pin

~ample pound Determ1n1gg turbine Power Output

The following data are taken trom that ot Run 1-9-1

Line voltage 1040 volts Line current 870 amperesSpeed 355 revolutions per minute

The induced voltage 1a determined as follows

Line voltage 1040

Voltage drop 90 using Figure 15 with line current of 870 amperes and temperature ot 122 degrees)

Induced Toltage 1130 volta

The power output of the turbine is determined as follows

Generator output 90$0 (line voltage z line current)

Oopper loss 7 (using Figure 15 with line current of 870 amperes and temperatUe or 122 degrees)

Stray power lose 470 (using Figure 16 with speed ot 355 revolutions per miDUte and induced voltage or 1130 volts)

Turbine power output 9527 vatta

or turbine power output 1s 12z2 horsepower

43

The conversion of the calculated data to a constant

head is based on the conventional assumption of constant

efficiency regardless of turbine head For a constant head

ot 81 teet a purely arbitrary figure the tollowing relashy

tionships are ass1lJiled to be true

I ____L (9) (i)l72

(10)

For these two values the specific a peed may be combull

putedt

N t Jt VPt (11)8 243

Chapter VI

~RESULTS

A -Pr_e_ae_n_t_a_t_t_o~n g Reaultbull

Graphical presentation ot the results ot this te1t

are given as follows

Figure 17 -Turbine characteristics with 100~ dratt

tuba 1low area

Figure 18 - Turbine characteristics with 7S dratt

tube tlow area

Figure 19 bull Comparison ot power and etticiency at

over gate conditions between 100 and

75~ draft tube flow area

Figure 20 bull COZQparison of power and ettic1ency at

halt gate conditions between 100~ and

7S~ draft tube flow area

Figure 21 bull Comparison of power and etticiency at

over gate condition between 100~ and

So dratt tube tlow area

Figure 22 - Comparison in variation ot apec1t1c

speed between 100 and 75~ dratt tube

tlow area

50

45

20

-bull - 1--shy40

bull J-~ 30

~ ex

~ 20

~~ ~ -)q

I

~ - _

- -

10~ OF DRAFT TUBE FL(Jif AREA

CONSTANT HEAD OF 8l FEST10

POIER OUTPUT EFFICIENCY SPECIFIC SPEED

0 ~--------------_--------~------~------~ 400 600 800 1000 1200 1400

TURBINE SPEED (RPM)

Figure 17 - Turbine Char~cteristics with 100 Draft Tube Flow Area

50

46

-bulllle

~ 7 ~ OF DRAFt TUBE FLOW AREA

0 -~~-rl C05STAMT BEAD OF 81 mET 1J~

POIER OOTPUT ---+- ---o ~_H EFFICIDCY ~ I shy

bull ql SPECIFIC SPEKD - ~ -

bull ~ J 10 L rmiddotr- r- -

bullz- I

~~ 30 ~~--~----~~-

20 ~ ~ middot-shy

26

~~ 25

~0 ~r-----i (

Tbull -bullshy

400 600 800 1000 1200 1400

TURBINE SPEED (R PK )

Figure 18 -Turbine Characteristics with 75 Draft Tube Flow Area

47

EFFICIENCY 60

1-----shy

-~ 50~--~--~~-~middot middot middot middot r~-~----~~~~---4~-r~-~~gtt

II

POWER~ J ~ bull bull

u I

sH

40~------+-------+---- -~~--~~-~~~~

~----~rl 1 bull

I

I

0~--------------~------_------~--------

~ -OVER GATE CONDITION

COIJSTANT HEAD OF 81 FEET

0 o 10~ DRAFt TUBE

_-- _ 7~ DRAFT TUBamp FLON AREA II

10_~-----+--------r-------r----~~

400 600 800 1000 1200 1400

TURBINE SPEED (RPM)

Figure 19 middot - Comparison between 75 and 100 Draft Tube Flow Areas of Power and Efficiency at Over Gate Conshydition

48

t

bull --4 r ~- ~ middot~

70 1-----------+-~~~~~+middot ~ ~~ middot middot -~~--~~--------~~----~-+1

-~-

Atbull bull

lla-

60

amp0

40

20

10

oampOO

t _ - - ~-+- - -~-

l2 GATB COJIDITIOJJ

COJISTABT HJW) OF 81 JBET

o 0 lOQ( DRAFl TUB8 FLOI AREA

e-- - e 75 DRAFT TUBE FLOW AREA

800 1000

- r-

~

TURBIbull SPBIID (RPII)

Figure 20 - Comparison between 75 and 100 Draft Tube Flow Areas of Power and Efficiency at Half Gate Conshydition

49

60

50

-40

bull 30

IIQbull

20

10

0

400

- t - ~

EFFICIENCY

_J bull - bull bull

~ r r middot t -+ shy L -t -

OVER GAD COliDITIOI

CONSTABT BEAD OF 8l FBB

o o 10~ DRAFt TUBE FLOI ADA middot--- 5~ DRAF TUBE FLQPi AREA

600 800 1000 1200

Figure 21 -Comparison between 50~ and 100~ Draft Tube Flow Areas of Power and Efficiency at Ove~ Gate Conshydition

50

25

20

15

10

0

Figure 22

~- T -4 -t- -l --~-

t-~ I

middot --~- t ~---- _ __ _ + --

----~- --r-- --

~-=J-~-=-~ -==~ _ ~- -- ---f---1 - shy

CONSTANT HEAD OF 81 FEBT

o--o 1~ DRAFT TUBE FLltll AREA

75C DRMT TUBK FLCIJ AREAmiddot--middot-middot 600 800 1000

TURBINE SPEED (RPK)

Comparison of Specific Speeds for 75 and 100 Draft Tube Flow Areas

51

B Discussion 2 Result

Consideration of Figures 17 and 18 indicates the

overall eftioi ncy pattern or hill is significantly or

rounded for the 7$~ flow area than for the 100~ flow area

bia implies a greateP efficiency is possible at speeds

leas than or greater than design speed with an insert in

the draft tube However the muilDum efficiency is lemiddotas

Direct comparison at over gate conditions is made in

Figure 19 ~e same general trend is noted tor both the

etticiency and power curves for the 7$~ flow area case

The eurves show higher values at overspeed than do the

correaponding cWvea for the 100 flow area case It ia

not clear whether the curves have been shifted by the dratt

tube constriction or whether the curves simply bulge past

the normal curves at both overspeed and underspeed condishy

tions The power curves apparently peak near the aeme

point bullalthough maximum power is still obtained with the

normal draft tube area

For the comparison at halt gate operation shown in

Figure 20 a general improvement has apparently been made

by restriction of the draft tube flow area At every speed

the etticienoy and the power is greater for the restricted

tlow case The two ett1o1ency curves and two power curvea

are practically parallel throughout the speed range ot

teat

As the flou aroa i e decreased still farther a s1gn1

ticant change appears Reterr1ng to Figllle 211 tor the $0

flow area curves it a obvious that exit losses have

become excessive at the overgate condition because the

efficiency and power are everywhere leas than tor the case

of normal draf t tube area

Earlier it was pointed out t hat 1t the r esult s 1nd1bull

eated an increase in both power and ef tieiency- t hen it

could be assumed tha t the additional los s i ntroduced with

the draft tube insert is less than the diminished losses

due to leas shock losa and water passage losses For the

places where both the efficiency and power have been

increased we can assume that the insert has improved turshy

bine performance

For the places where the power haa been decreased

nothing can be said as to the elimination of ampbock loss

because the new lose present with the drat tube insert has

overshadowed any gains in eftecti Ve head upatJ-eam of the

insert

Near the peak of the efficiency hill howeve~ it may

be pointed out t hat shock loaa ie a minimum with a normal

draft tube and the insert merely adds an additional loss

with the resultant decrease in maximum efficiency tor the

7$~ flow area case

Perhaps the most s1gn1ticant set of eurves is shown aa

53

Figure 22 In this graph values of specific speed tor the

75 and 100~ flow area cases for both over gate and one

halt gate openings are plotted against turbine speed At

every speed and both gate openings the value ot specific

speed for th 75~ flow area case is greater than that for

the 100 t1ow area ease

Since the head is a constant for both situations this

may be interpreted in either of two ways trom equation

(11)

(1) For the same turbine apeed restriction of the

draft tube t1ow area resulted in greater turbine power

(2) For the same power amputput the turbine with 75~

draft tube flow area operated at a greater speed than did

the one with 100 flow area

Since the required diameter of a turbine varies

inversely with the speed the second interpretation could

be stated such that a smaller turbine could be used to

develop the same power output

Whether viewed trom the aspect of increased power

greater speed or reduced size the performance of the turshy

bine with reduced draft tube flow area is superior to that

with the nolmal flow are in the draft tube

The curve of specmiddotific speed versus turbine speed for

the so draft tube flow area case at over gate cond1t1ona

was not included in Figure 22 This curve lies below that

for the 100~ flow area c se at all speeds

In elaboration ot the second interpretation of Figure

22 attention is directed to the relative magnitudes ot

increased apee1f1c speed tor the two gate openings Assumbull

ing that the increase in specific speed implies a shift ot

the power curve to the right along the turbine speed scale

the power curve would be shifted more tor tbe halt gate

opening than tor the over gate opening

It thia trend could be extrapolated to the other gate

openings the tendency can be seen tor the line ot beat

speed to rotate toward the line of the operating speed as

illustrated in FigtU-e ) The advantage of this has already

been discussed

This particular turbine has a low specific speed tor a

reaction turbine Aa the rated value of apecitic apeed tor

reaction turbines increases the line ot beat speed departs

even more radically from the line of operating bullpeed It a

test similar to this were conducted on a reaction turbine

ot gleater specific speed it is pJobable t hat the rotation

ot the line of beat apeed would become more p~onounced

The scheme used in th1a teat had two obvious dr wbull

backs The first was the decision to leave all the wicket

gamiddottes installed tor all conditions ot the draft tube

These gates predominated in control of the tlow The

inserts added to the draft tube merely acted as auxiliary

55

contrGla

The aecond drawback was the choice or device to place

in the draft tube The reasons foll selection of this type

of device have been previously mentioned It is to be

anticipated that adaptation ot dratt tube flow control

would result 1n a better device for an actual turbine

installation Such apparatus might take the form of a

pneumatic bladder or a h7drau11oally operated variable

venturi section in the draft tube It is conceivable that

the gate as used in this test might be adapted also

Chapter VII

OONCLtJSIOfS

From the results of this test the following eonolubull

e1ona aa to the effect ot a variable draft tube flow area

on the performance or a r action turbine may be drawn

(1) The effect ot a variable draft tube tlow area 1a

generally favorable upon the operat1Gn ot a reaction turbull

bine because or the tendency tor the line or beat speed to

rotate toward the line ot operation This resulte in

better performance of the turbine at partbullloads

(2) he etf1o1ency eh111 tor the turbine beeomaa JDore

tlat at the top leading to a smaller max1JilWD effic1enc7

but e reater etticieney at other pointe of operation with

the insertion ot an auxiliary control ror the rate ot tlov

in the draft tube

(3) The power output of the turbine will increase at

over speed over gate conditione as well a at part gate

conditions with the proper amount or draft tube eonatr1cbull

tion or flow

(4) It is possible to eliminate at least partially

eddy type shock loss by tho introduction ot flow control

in the draft tube

BIBLIOGRAPBl

1 Addison Herbert A treatise on applied h-draul1cs New York Wiley 1954 724 Pbull

2 Allen o M and I A Winter middot Co111parative testa on experimental draft tubes Tranaact1ons ot the American ociety ot Civil Engineers 87t893bull970 1924

3 Barrows a E Water power engineering 3d ed ew York McGraw-Bill 1943 791 Pbull

Bovet G A Modern trenda in hydraulic turbine design4middot in Europe Tranaactions of the American Society ot Mechanical Engineera 75975bull993 1953bull

s Oreager William P and Joel D Justin Hydroelectrichandbook 2d ed New York Wiley 19$0 1151 Pbull

6 Daily Jamea w Hydraulic machinery Int Hunter Rouses Engineering hydraulics Hew York Wiley 19$0 p 8$8bull99

Daughertybull Robert L Bydraulie turbines ew Yorkbull7middot MoGrav-Hlll 1920 281 Pbull

8 Daugherty Robert L Inveat1gat1on of tne performance ot a reaction turbine ~anaactiona or the American Society ot Civil Engineers 7811270bull1304 1915

9 Davie L M Model and prototype testa Int Trend in hydraulle turbine practice symposium lranaactions ot the American Society ot Civil Engineers 1o63S3middot368 1941

lfJ Doland James J Hydro power engineering Hew Yorkbull Ronald 1954 209 Pbull

11 Gandy Theodore s and Elmer c Schacht Direct curshyrent motor and generator troubles operation and repair New York McGraw-Bill 1911 293 Pbull

12 Gibaon Arnold H Hydraulics and ita applications5th ed London Constable 1952 813 Pbull

58

13 Button s P Component loases in Kaplan turbinebull and The prediction of efficiency from model tests Probull coedings of the Institution or Mechanical Engineers168743-762 1954

14 Knapp R T~ Oavit t1on mechanics and its relation to the d sign or hydraulic equip ent Proceedings or tne Institution ot Mechanical Engineers 166150bull16) 1952

15 Langsdorf Alexander s Principles of direct curHnt mach1nee 5th ed New York r~cGrawbullH1ll 1940 746 Pbull

16 Lsrner Chester w Characteristica of modern hydraubull lie turbines Trans e~ions of the ~~erican Society ot Civil Engineers 66306-386 1910

17 Linsley Ray K Jr and Jobulleph B Franzin1 Eleshyments of hydraulic enginebullring New York McGrawshyBill 19$5 $82 Pbull

18 Mead Daniel w Hydraulic machinery llev York McGraw-Hill 1933 396 Pbull

19 ead Daniel w Water power engineering New York McGrawbullRill 191S 843 Pbull

20 Mockmore Charles A Part gate operation at water turbines Corvallis Oregon State College Department ot Civil Engineering 1933 11 numb leaves (Unpubshylshed typescript)

21 Mockmore Oharles A Flow characteristics in elbow dratt tubes Transactions of the Amez-ican Society ot Civil Engineers 103402middot464bull 1938

22 Moody L F Hydraulic machinery In c v Davis Handbook ot applied hydraulics New York McGrawshyHlll 1942 1082 Pbull

2) Ptau At-nold Hydrbullulie turbine handbook ld ed Milwaukee AllisbullOhalmers ManufactUIing Company 1948 70 Pbull

RheingalUI w J Recent developments in Francis turshybines Mechanical Engineering 74189-196 1952

25 Russell George E Hydraulica 5th ed New York Henry Holt 1942 466 Pbull

26 Safford A and E P- Hamilton American mixed tlow turbine and ita setting Tranampactions or the Amerieal Society of Civil Engineers 851237bull1)56 1922

27 bull Spannhake W1lhe1Dh Problems or modern pump and tur b1ne design Transactions of the American Society of Mechanical Engineers 56e22$-248 1934bull

28 Sutherlandraquo R A Better ethod or representing and middot tudying water turbine performance ~ansaetions ot thmiddote American Society of Mechanical Engineers 68t675bull 686 1946

29 Teats ot five models or draft tubes tor turbines Engineering News-Record Pbull 182-184 Aug 2 1923

30 White w M American hydztaulic turbines Mechanical Engineering S2t390bull39S 1930bull

31 White w M lhe hydraucGne rega1ner1 its developmentand appl1eat1ons 1n hydroelectric plants Meohanlobulll Engineering 43t37Sbull380 1921 middot

32 Winter I A Economic principlebull in designbull Int Trend in hydraulic urbin practice bull a ampoeiumTranaaot1ona ot the American Society ot Civil Engineerslo6332bull3S2 1941

33 Wiel1cenua G F Fluid mechan1ca or turbo-machineryNev York McGraw-Hill 1947 613 Pbull

APPENDICES

c

Appendix A

NOATIOB

A Angle between the absolute velocity vector and the tangent to the rwmer Subscripts 1 and 2 refel to entrance and exit ot the runner blade

B Angle between the relative 1elooity vector and the tangent to the rwmer Subscripta 1 and 2 refer to entrance and ezit or the runner blade

Angle between the tangent to the runner blade tip and the tangent to the runnel- Subscripts 1 and 2 reter to entrance and exit of the rt1rmer bladebull

Blade angle-gate opening conetant defined by equation (1)

e 09erall efficiency

g Gravitational acceleration assumed constant at 322 teet per second per second bull

H Turbine head detined by equation ($)

m Exit loss coeft1e1ent

Turbine speed expressed in revolutions per minute

Turbine speed under a constant head of 81 teet

specitic apeed of the turbine under a constant head ot 81 teet

p Power output in horsepower ot the tvbine

Power output of the turbine Ulder a constant head ot Sl teet

Pl- Pressure head at entrance to the tUlb1new

l1 Peripheral velocity ot the runneP Subacr1pta 1 and 2 refer to entrance and exit ot the JUnllampr blade

62

v Relative velocity reaulting trom the combination ot the absolute water velocity V and the runner periphshyeral velocity u Subscripts 1 and 2 refer to entrance and exit ot the runner blade

v] Relative velocity vector necessary to produce a tanbull gential entry into the runner blades

V Absolute water velocity Subscripts l and 2 refer to entrano and exit ot the runner blade

v2 Velocity head Subscripts 1 and 4 reter to the ~8 entrance to the turbine and the tail~ace wate~

w Unit weight ot water assumed constant at 624 pounda per cubic toot

V Weight rate ot flow in pounds per aeooncl

XX Velocity component ot ahook See Figule 2

Z Elevation head Subscripts 1 and 4 reter to entrance to the turbine and the taibace water surfacebull

Appendix B ORIGINAL DATA-Run

lfwnber

0-4-1 0-4-2 0-4-3 o-4-4 o-4-S o-4-6 0-4-7 0-4-8 0-4-9o-4-lo o-4-11 o-4-12 0-4-13

o-6-1 o-6-2 06-3 o-6-4o-6middotS o-6-6 o-6-7 o-6-8 0-6-9 o--6-lo o-6-11

Speed

rmiddot2middotbullmiddot(1)

336 38$ 451 S$9 620 669 6lt)$ 120 787 860 932

102imiddot109 bull

352 355 443middot 543middot 620 654AJs32

911 1001 1111

~essure Head rt (2)

410 410 416 426 431 43-7 439 44-9 452 467 482 soo $1 bull $

350 351 35middot7 )66 37-9 37-9 392 41 bull 3 43middot3 460 489

Elevation Bead

fjj $7 $7 $7 $7 $7 $7 51 57 5-15858 $8 58 56 56 $6565656 51 575As5a

Velocit Head

flj 07 07 07 06 06 06 06 os 05 os0404 03

09 09 oa o8 o8 os 07 07 06 o~o

Total Head rt ($)

47middot4 4A44 o 489 49-4 soo $02 $11 $14 $29 5imiddot45 2 576

41 bull $ 416 421 430 44middot3 44middot3 456 47-7 496 523551

Plow

lbtjec

326 324middot317 311 306 30029middot28 middotmiddot middot 386 275middot260 240 218

359 36~35 bull 349 345middot 339 330 318 300 273 240

Line Potential

vyqjbull 1060 1220 ~-0o 1920 2150 2000 2$60 2000 1940 18)015io11 o

1000 1100 139bull5 1760 1925 16$0 1620 1610 1540 1330 870

Line Current

amlscs 960 900 830 740 730655 70bull 0 530 660 600 5imiddot54 6 )60

982 930 860 780 ~3-545

79-5 74-5 670 560 370

P

Appendix B ORIGINAL DATA (Continued)

Run Number

Speed

Pbulltmiddotbullmiddot )

leasure Head ft(2

Elevation Head tt(J)

Velocity He-dfmiddotj

Total Bead tt($

Flow

lbstsec( )

Line Potential vo~ta( )

Line Current

amjs (sect

0bulllt)-1 0-9-2

3ll6 398

28o ~~1

$6 56

1o 10

346 347

390 365

1ooo 1190

aao 835

0-9-3 0-9-4 o-9-S

472 565 632

292 305 312

$6 s6 56

10 o9 o9

)$8 J7~o 37~7

381376 37o

1)6614oo 141o

820 ass ass o-9-6 0-9-7 0-9-8 o-9-9 0middot9-10

680 120 762 844 920

)24337346 366 390

56 $6 56 57 $7

09 os o8 oa 07

)89401 410 431454

367~ 357348 34o 322

1400 1J6o l36o 1310 1170

843 820 7957So 67~0

0-9-ll 0-912

1001 1100

41 bull 7 45-3

s 7 6~0

06 os 480 $18

299 268

980 65$

560 36~5

1-4-1 1-4-21-4-l1-4shy1-4-5 1-4-6 l-4-7 1 4-8 1-4-9 1-4-10 1middot4-ll 1-4bull12

354middot452 562 62q 674shy102 752 760- 863 932

1022 1100-

)82389 4014oa 416 41--7 423 428 44-2 45-7 486 49-2

51S757 51 5-7 5middot15zs sa $8 58 59

07 07 06 06 06 06 06 os o bull o 04 o J

446 45-)46middot4 471 ti7-9480 q86 491505 $19 548 55-4

)28 320 311 306 300 295 291 286 269 2582iimiddot21 bull

1080 14Lo 1550 153-5 1470 141-0 1385 1310 1310 1230 1120 855

970855 875 91-0 94~0 975 966 995 860 77-S 610 4fo

0 ~

Appendix B ORIGINAL DATA (Contirmed)-Run Speed Pressure Elevation Velocity Total Flow Line Line

Number Head Head Head had Potential Current rtjjmbull t~ bttec vyfs am~a12) ( ) ti fli 8

1-6-l $6 33$ $6 0bull9 400 364 1100 93 0 1-6-2 41 34laquo2 $6 oa 406 JS7middot iios a5s l-6-3 500 3~0 5bull6 os 356 1 1 o aos 41middot~1-6~4 35bull4 5-6 oa 41middot 352 16~0 82 0 5~1-6-5 5 bull 36_2 Sbull6 08 42bull6 349middot 161 ~ 0 86~0 1-6-6 622 366 $6 oe 43bull0 345middot 158 0 88~$ 16-A 649bull 37bull1 56 os 43-S 342middot 1570 895 1~- 386 57 07 46-0 192 ) 125A44 333middot 1-6-9 3) 404 5middot1 07 468 317 1620 675 1610 911 42-4 5-7 o6 48-7 298 168 0 61 0 1-6-11 999 451 56 os Sl ll 276 ~2-0 530 1-612 1115 485 58 04 54middot7 238 90 )3 0

1middot9-l 355 279 56 10 )45 385 1040 870 1-9-2 399 28J $6 10 )49 38$ 1140 86 5 l-9-3 ~ ao 291 56 ~0 35middot1 J8J_ JJ6o 815 1bull9-4 579 303 56 09 )68 375middot J4JO 830 l-9bullS 40- 313 )6 09 31middot8 370- 1460 82~0 1-9bull6 679 2) 56 09 3 bull8 364middot 1670 710 l-9-7 682 319 56 o9 384 ) 62 1460 79 5 l-9-8 724 33middot5 56 o8 399 3$6 bull 1480 76 -5 1-9-9 762 34middot3 $6 0 bull 8 407 )48 14910 13middotS 1-9-10 833middot )60 5middot7 os 42$ 339 144$ 686 1-9-ll 926 39middot1 5-7 07 455 318 1290 600 1-9-12 1000 41middot3 0-6 476 298 1115 510$ ~ 1middot9-13 1105 452 s o4 $14 2$6 710 )10

~

Appendix Bt ORIGDIAL J (Continued)

Run Speed Pressure Elevation Velocity Total Plow Line Line Number Head ltead Head jlamp$d P()ten~ibulll Current

r~~~m ft ft lbs~seo voltattj rgj twimiddot t 1 t2gt lt3 ou t ( rt

2-9-1 384 289 S 6 10 35 5 1400 1170 810 2-9-2 443middot 29$ $6 ltimiddot9 360 379middot 11(0 87$ 2-9-J 536 30bull 3 sc 09 )68 374middot 1)40 84 bull) 2-9-4 571 306 $6 09 3~1 372 120bull 0 955 2-9-5 623 316 S6 09 J l )6S UJSo 77$ 2bull9-6 669 327 S6 09 )92 )61 1240 905 2-9bull7 712 )39 56 os 40-3 351 12(0 86 bull0 2-9-8 ~5$~ J48 56 oa 412 348 1290 81 bull ) 2-9-9 04 )63 56 oa 42-7 339 12ltJO 76$ 2middotmiddot9-10 8$2 376 5middot1 07 440 33~- ~ o 710 2-9-11 955 394 5-1 o6 457 300 1100 506 2middot9-12 1000 421 $7 06 48middoti 295 1020 $18 2-9bull13 110~ 463 56 05 $2 267 620 3~0

oshy0

Appendix Gt CALCULATED DAgA

Turbine Run Generator Generator Turbine Turbine Efficiency Turbine Turbine Specit1c

Number OutputKWlt21

Loa~Jes KWlol

Outut K bull (H)

Input RP 12)

middot Percentlt13gt

Speed r~Jmiddot(

0ltput HP ~1

Speed r-m

( 6) middot

o-4-1 0middot4-2 0-4-3 0-4-4 0-4-5 0-4-6 O-qmiddot7o-4-8o-4-9 0-4bull10 0-4-11 o-4-12

1018 1o9a 1220 1)62J40214oa1J4oo 1357 1320 1164 997 718

046 o59 071 092 096 1071oo 134 104 100 109 107

14261sso 17)01948 2008 20322011 1999 19 09 1708 14-84 11o6

281279 27-7 276 215 273271 268 268 26h 258 24-5

soa 555 62$ 705 7)1145 742 74-6714645 51s 45-1

440 sos 585 720 195 sso sao 9$$ 985

1065 1135middot 1230

318 357 319 416 422 419412 39middot9 378 324 260 191

102 12bull4 148 191 21bull 3 22o 233 249 24924middot9 238 221

0-4middot13 418 104 699 228 306 1300 117 18)

o-6-1 982 045 1376 271 $08 496 376 124 o-6-2 o-6-3 G-6-4o-6-5 0-6-6

1023 1200 13 73 J415 139h

051 0middot66 oaa ()bull 96 088

14-39 1696 1958 2026 1986

276 27middot4 273 278 274

$20 61 8 717 7)0726

q95615745 8)5685

390 ll5middot3 sos soo 490

127 170 218 243 2$$

o-6-7 o-6-8 o-6-9o-6-lo

1288 1199 1032 7-45

o9o 094 09$ 096

1846 1733 1511 1128

274 276 271 260

67S 629559 43middot4

980 1085 1165 1245shy

436 )83316 21bull 7

266 276 270 239

0-6-11 322 1oo 566 2141 2JS 1350 101 177 0 --4

Appendix C CALCULATED DAlA ( Continued)-Run

Number Generator Generator

Out2ut Losaes xw LW- 12gt (lO)

Turbine Out2ut

ltPlJ

Turbine Inat lfP Jig)

Etpound1e1ency

PireentDl

Turbine Sed x-~m( 1

Turbine OutEut RPJl)

Turbine Specific

SeeedrIbullntbull

( 6)

o-9middot1 0-9-2 0-9-3 o-lt)-4 09-$ 0bull9-6 0-9-7 0-9-8 0-9-9 0-9-10 o-9-11 0-9-12

aao 994

111$ 1197 1206 1180 11)21081 982 784 5-49 2)9

0middot45oss o6$ 070 07$ 0-77 (l77 or~ o s06o 8 096

123~ 1402 1$80 1698 17bulllS 168$ 16bull18 ~middot5430 1151 a~J4 9

24middotgt24middot3248 25~25 260 260 259 267 266 26middot1 2S2

sos 577 63-7 671 676 650 621 60036J4

327 178

$) 610AlO 3$

92S 980

102$ 1070 1157middot 1230 1300 137Smiddot

44middot4 soo 523 ssomiddot 540so6 46-5 432 368 274 18~8

J46 176 21-1 255 2802s_A 28 289 288 265 231 168

1-4-1 1-4middot2 1-4-3 1-4-4 1-4-5 1-4-6 1-4-7 1-J-8 1-4~9 1-4-10 1-4-11 1-4-12

10bull48 1231 13-S6 1397 1)821375 1))8 1303 1127 953 683) 51

048 067 o7A07 0 bull79 oa1 oss o bullao osa 0lt)0 096 099

J468 1740 1921 1978 1958 19$1 1911 lSSi162 1)98 1045

603

266 264 262 262 261 2512$7 2$6 24middot7 24-3 233 217

551 660 13middot3155 75-6 7~-97 middot4 72$ 67 51middotJ 44middot9 21middot1

475 605 A4220

875middot 910 970_

1000 1090bull 1166 1243 1330

5816

44middot444middot5 430 427 412 392 329 273 188 l0-7

117 101 204 22$ 2)7245 2562sa 257251 222 179

a-C))

Appendix Ct CALCULATED -DATA ( Ocntinued)

1-6middot1 1023 o$2 14-41 26S 505 41~6 26~

54middot5 13middot3l-6-2 1201 067 1boo 625 47-9 17shy~middot41-6bull3 1296 oA9 1 middot43 26 9 700 so5 20bull 4 l-6-4 l3j5 o 0 19~09 268 71bull3 A5o 514 222 1-6-5 1) 5 o81 19(gt4 271 725 51-5 238 l-66 1398 081 198) 27-0 736 8 S13 252~-middot l-6j 1405 083 199i 211 733 885 $middot06 2$9 l-6 13middot9~ 103 2amp 0 279 71 8 985~ 467 ~-69 1228 1 bull 02 17-SS 270 661 109$ 407 ~3~ l-6bull10 1025 100 lSll 26i 573 1175middot 27~S32middot~l-ampu 153 1-00 llft3 26 444 1270 22 24bull8 1bull6-12 294 100 52a 231 22 3 1360 95 172

1-9bull1 904 048 1275 2J4Z $28 S4$ 459 1$2 1-92 98$ oss 13-92 24middot4 57-0 6JO 49bull1 176 1-9middot3 1110 066 1$76 24middot9 63middot4 I2o 536 21-7 l--9-4 1187 072 1685 251 66$ 5 $$ bull 0 261 1middot9-5 llltJ7 1710 25middot4 67-3 93$ 536 28~20-671middot9-6 1186 o 8 1708 25-7 67) 980 $15 2691-9- 1161 oBo 1660 2$middot3 6$6 990 508 29-1 l~- ll-32 oB) 16sect0 2$8 632 1030 471 291 1-9bull9 109$ oa5 2$7 614 1075 29S~middot 0 4imiddot41-9-10 9~91 oas 262 S$1 1150~ 3 o 292 1-9-11 o9o u57 12JiO 21gt 26-77middot74

-45 26sect ~middot91-912 $69 091 sas 25 middot3 1)0$ 196 2J-8 1-9-1) 220 098 426 2)9 178 1390middot 84 16 6

0 0

Appendx C CALCULATED DATA (Continued)

Turbine Run Generator Generator lurbine Turbine Eft1e1eney Turbine lurbine Spee1f1c

Number Output Losses Outit Input Speed Output SPed middot k_-V KW R _ H_bull_P Percent r Thm HP rpm_ (9) tlo) 11) middot (12 _) (lJI ( ) (1$ (14)

2-9-1 9--46 055 1)62 258 528 580 164 2-9-2 1024 056 248 58 4 665 4 9 191iimiddot48 4~middot0 2-9-3 1132 067 05 2$0 641 795 52q 237 2-9-4 1148 065 1027 2$1 -~8 845 525 252 2-9-5 11 77 oso 16-83 253 6 910~ 522 270 2-9 6 1122 071 1600 251 622 960 47-5 2722-9-A 1092 015 1562 257 608 1010 445 2z12bull9- 1052 079 1514 261 580 1060 41middot7 2 2 2middot9-9 986 o82 ]429 26) 542 1105 372 277 2-9-10 915 086 1340 268 500 1160 334 27-6 2-9-11 638 087 972 254 )81 1270~ 229 250 2-9-12 )28 090 828 259 )19 1295 179 226 2-9-13 192 094 383 2$ 6 150 1370 7 3 152

-3 0

Page 4: The Effect of A Variable Draft Tube Flow Area on the

nor finished without the inapirat1on1 ideas and criticisms

of Fl-ed Merryfield Professor ot Sanitary Engineering to

whom a special debt is owed

Grant Robley Aas1stant Dean or t he School of Engibull

neering or Yal Un1ver ity ia the cause or it all

Arl1sa D Ray

bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull

bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull

bull bull bull bull

bull bull bull bull bull bull bull bull bull bull

bull bull bull bull bull bull bull bull bull bull bull bull bull

TABLE Qf CONTENTS

Chapter

I INTRODUCTION bull

A Purpose and Scope of Investigation bull bull bull bull l B Reaction Turbinea bull bull bull bull bull bull bull bull bull bull bull bull 2 C Draft Tubes bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull 5

II DISCUSSION OF TURBI NE LOSSES bull bull bull bull bull bull bull bull 1

A General bull a Shock Loae ~ c Exit Loss 12

III PROPOSAL OF ALTERNATE METHOD OF CONTROL bull bull bull bullbull 14 A Type and Location of Control bull bull bull bull bull bull bull B Estimated Eftect on Actual Turbine bull bull bull bull ~ c Requirements tor Teet Verification bull bull bull bull 19

IV APPARATUS AND METHODS OP TESl bull bull bull bull bull bull bull bull bull 23

A Equipment bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull 23 B InatlWilentation and Measuring Devicbullbull bull bull 26 c Operational Pz-ocedure bull bull bull bull bull bull bull bull bull bull 26 D Schedule ot Rune bull bull bull bull bull bull bull bull bull bull bull bull bull JS

v DATA bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull 37

A Original Data bull bull bull bull bull bull bull bull bull bull B Calculated Data bull bull bull bull bull bull bull bull bull bull bull bull bull ~A

VI TEST RESULTS bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull 44 A Presentation of Results bull bull bull bull bull bull bull bull bull 44B Discussion of aeaults $1

VII CONCLUSIONS bull middot 56bull bull bull bull bull bull bull bull bull bull bull BIBLIOGRAPY bull bull bull bull bull bull bull bull bull bull bull 51 APPENDICES bull bull bull bull bull bull bull bull bull bull bull 60

A lfotation bull bull bull bull 61 B Original Data bull bull bull bull bull bull bull bull bull bull bull bull bull bull 6)c Calculated Data bull bull bull bull bull bull bull bull bull bull bull 67

bull bull bull bull bull bull bull bull bull bull bull

bull bull

bull bull

LIS~ OP_ __ ILLUSTRAfiOBS-middot

Fiere Page

1 13 $ Inch Reaction turbine bull bull bull bull bull bull bull bull bull bull 4

s bull bull bull bull bull bull bull bull bull bull bull bull

Plow Area bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull 4S

2 Turbine Runner Vector D1agrama and Shook Loaa Diaptama bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull 10

) Turbine PertoPmance CurYea bull bull bull bull bull bull bull bull bull bull 20

4 General View ot Teat Equipment bull bull bull bull bull bull bull 21

6 View ot Teat ut-bine bull bull bullmiddot bull bull bull bull bull bull bull bull bull 7 Teat Generator and Platform bull bull bull bull bull bull bull bull bull 27

8 Iutrument Board and Field Rheostat bull bull bull bull bull 27

9 Vlev ot Water lUteoatat bull bull bull bull bull bull bull bull bull bull 29

10 View or Water Rheostat bull 29

11 Vater Plow Diagram and Electrical Laout bull bull bull 30

12 Sketoh ot Draft ltlbe and Teat Inaerta bullbull bull bull 33

13 View ot Dratt Ube Inaer bull bull bull bull bull bull bull bull bull bull 34

14 Vlev ot Dr~t lube Iuert bull bull bull bull bull bull bull bull bull 34 lS Curves ot Generator Voltage Drop and Copper

Lose bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull 40 16 euvtee of Oenerator Stray Power Lobullbull bull bull bull 41 17 Turbine Charae ter1at1ca with lOOC Dl-att lUbe

18 Turbine Characteristicbull With 7SC Draft tube Flow Area bull bull bull bull bull bull bull bull bull bull bullbull bull bullbull 46

19 Comparleon Between 7S~ and 100 Pratt Tubbull Flow Areas ot Power and Etf1c1ency at OVer Gate Condition bull bull bullbullbull bull bullbullbullbullbullbull 47

bull bull

~ Q ILLt1SlATlOIS (Continued)

F1pe

20 Comparison Between 15 and 100~ Draft Tube Flow Areas of PoweP and Ett1c1enoy at Halt Gate Condition bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull 46

21 Oompu1aon Betwen S~ and 100~ Draft Tube Flow ANaa ot Po-r and Efflctency ab Ovbullbull Gate Condftimiddoton bull - bull bull bull bull - bull bull middot bull bull bull 49 Compar1aon ot Spec1tic Speeda tor 75~ middotand 10~ Draft Tube Flow Areae bull bull bull bull bull bull bull bull so

I

bull

filE EPPEOI OF A VARIABLE DRAFT TUBE FLOW AREA

ON THE PERFORMANltJE OF A REAOTIO TURBINE

Chapter l

IITRODUClIOH

A hrpose and Scope of Invst1pt1on

Present day control of reaction turbines is accombull

pl1ahed by the use of wicket gates immediately- preceding

the turbine runner These gates otter an interrelated conbull

- trol to the quantity and direction ot the water entering

t-he runner ie a change in the amount ot flow will rebull

middot ult in a change in direction This combined control leada

to loesee at all but the rated or design condition ot the

turbine (2$ Pbull )71)

This investigation dealt with an att mpt to better

turbine performance at all points of operation b y the

eatabliahment of separate controls over the rate of flow

and the d1J~ect1on ot the entering watebullbull

The only physical modification of the test tlutbine

was the insertion of flow restricting device in the dratt

tube

Ot primary interest were the trends in the change of

2

turbine performance with the amount ot draft tube tlow

area To this end complete turbine charaeteristiea were

not obtained tor 0ach device inserted in the draft tube

It was considered sutt1e1ent to obtain data tor the tull

speed range tor two representative gat openings one

greater and one less than the rated gate openingbull

Before proceeding with th report ot this 1nvest1gabull

t1on it 1a desirable to supply sa b ckground m terial

on reaction tw-blnes and their dratt tubes

B Raot1on 1rbinea

A hydraulic turbine is a device for converting the

energy in water to eohanical energy (6 Pbull 93lbull96S) furbull

b1nes may be loosely grouped into one of three elasse

impulsmiddote 1 reaot1on or propeller

An impulse turbine normally operates under a high head

and with a relatively sma~l amount ot watel in the converbull

sion or kinetic nergy to mechanical energy The propeller

turbine utilizes pressure energy to develop mechanical

energy while under a low head and p ss1ng a large amount of

waver

The reaction turbine lies somewhere between these two

extremes It changes both pressure and kinetic energy

while oper ting under a medium head with a moderate ount

opound water An example or a reaction turbine is pietur d in

Figure 1

lhe terms of high low small and so tomiddotrth are only

relative in sense A turbinebulls class1f1 eat1on is depenfent

upon its hoad rate of diacharge and speed of rot tion A

useful index tor turbine comparison (5 Pbull 825) is termed

specific speed and this ia a function of the rated ipeed

power output and head or the turbine The common range in

values ot speoitic speed ($ Pbull 826 ) tor each type ot tlirshy

bine is

Impulse J to SS tor one nozzle)Reaction bull 22 to 80 Propeller - 85 to 170

The development of t he reaction turbine began in the

early part or the nineteenth century (26 Pbull 1217bull1)6)

The trst efficient inward tlow turbine was de igned by

James B Francis an American in 1649bull For many years

turbine design was a matter of cutbullandbulltry in America an4

pure mathematical analysis 1n Europe It was not until the

two schools began exchanging ideas in the l$tter halt ot

the n1neteenth century that pronounced advancement was made

in the field

ObTioual7 the primary pux-pose ot any turbine inatallabull

t1on is t he production of power Added to this is the

restriction that the production or power must necessarily

be a controlled process An example of this is where the

turbine is direct-connected to an electric generator which

4

Figure 1 - 135 Inch Reaction Turbine

5

must operate at a constant speed or rotation even though _

the power demand ohangos In thiamp case the turbine nuet

be eap~able or producing a range of power output yet menshy

ta1n e eonetant speed

Speed regulation of the turbine iv accomplished by

means ot a governor (23 Pbull 24bull3-7) bull The contr-ol or regulashy

tion 1s indirect that i s the governor actually exereiaabull

control over the water in order to JJaintain e given speed

Co-ntrol over- the turbine end bence its speed and

power is the function ot a ring of movable wicket gates

located just upsttteam of the turbine runner These w1eket

gates 1n the process of opening and closing upon eeeh

0~1ar in a rotational manner actually control the amount

velocity and direction of tne water passing throu~~ them

C Draft Tubes

It has been found that the effeetive head on a reae

1l1on middotturbine is increased with the addi timiddoton of a draft tube

(3 Pbull 256bull264) Tne draft tube does thin by~

(1) Making a greater presaure d~op across the turbine

possible by the creation of a negative pressure at the

discharge or the runner and

2) DeoreaGing the k1net1e energy lost by increasing

the eross sectional area at exit

he draft tube permits the turbine runner to be

6

located above the tail race water surface without the

sacrifice of head However cavitation will cause pitting

of the turbine if the difference in elevation is too great

A common maximum elevation difference is 19 feet although

this figure is quite subject to modification between difshy

ferent installations (3 p middot 264-266)

There are many different types or draft tubes in use

today the choice or type being largely a matter or

economics (2$ p 368-370) A very common type particushy

larly among the smaller units is vertical with flaring

sides However the angle of flare is limited by the possishy

bility of separation of the flow from the sides In order

to achieve a certain discharge area the length of the tube

may be such as to require a great deal of excavation In

oases or this sort the cost of this excavation must be

balanced against a more elaborate design that does not

require as much excavation Other draft tubes in use

include the elbow hydracone and spreader types

Despite the differences found in construction and

design the draft tube must accomplish the desired objecshy

tives while offering a good hydraulic geometry to the flow

passing through it An inefficient draft tube defeats its

own purpose

Ohapter II

DISCUSSION ~ TURBINE LOSSES

A General

lhe head that 1a actually utilized by the turbine 1a

less than the effective bead as defined by equation ($) by

the amount that 1a lost due to mechanical and hydraulic

reasons

Mechanical loaaea are a function or the turbine 8p$ed

fhis ia not a lineaz- function but varies eomewhere between

N and N2 (3- Pbull 224)

Hydraulic losses encounteled in turbines ma- be subshy

divided aa to the location or occurrence (3 p 225-227) aa

fOllOW$S

(1) Penstock and scroll case

(2) Wicket gates

(3) Between wicket gates and turbine runner

(4) Runner passages

(5) Runner exit into draft tube

(6) Draft tube and

(7) At exit from the draft tube

The flow in the penstock scroll case wicket gates

runner passages and draft tube may be envisioned as

examples of flew in conventional pipes elbows and convergbull

1ng passages If this comparison may be made it could be

assumed that the losses encountered in these locations

would be proportional to vn ~ value ot N is normally2g

aesU111ed to be 2

he losses encountered between the wicket gates an4

the turbine runner and exit lossos are special cases which

will be discussed separately

B Shock toes_

The flow betwe n the wicket gat outlet and the runner

blade entrance is or particular 1nt rest because no direct

comparison vith common flow situations is obvious

Conaider the vector diagram (7 Pbull 7576) in Figure 2

The veetoo v1 is the absolute entering velocity of the

water and is fixed in magnitude and direction by the setbull

ting or the wicket gates The vector l11 1e the peripheztal

velocity of the runnel which tol any given turbine 1e

dependent only upon the turbine rotational speed The

combination of these two vectors ylelda the third vector

v1 which is the relative entering velocity ot the water

nere is only one setting ot the wicket gates for a

given turbine a peed that will produce an angle B1 which

coincides with the blade angle B1bull At other gate settings

the vector v1 will rotate and change in magnitude in such a

9

t ehion that B1 will beoome either greater or 1 sa than B1bull Th1 give rise to tbe phenomenon term d shock loasft

If B1 1a greater than B1 the relative ent ring veloebull

ityt v1 will have a compon~nt opposing the forward motion

of the runner The shock loss could be typified bullbull that

occasioned by direct impact or the water 0n the blade- If

E1 is lese than a] the vector l will overshoot the blade

and the flow will tend to eddy around the forward portion

or the blade tip

The shock loss can then be either due to impact or

eddying flow Since the area norm 1 to the radius at outlampt

of the w1eket gftee is essentially equ 1 to the area normnl

to the rad1u~ at the inlet to the turbine runner the combull

ponents ot vl and vl perpendicular to ul will b approxishy

mately equal This leads to the conclusion that xxbull ~epresenting the shock vector 1 parallel to Ulbull

For either the impact or eddy case the trigonometric

law of $1nee leads tot

XX

bull ul - sin (Bi-Al) vl eln Bi

It it 1a assumed that the energy lost in the shock 1a

the Telocity head ot the shock component XX then

10

VELOCITY VECTOR DIAGIWI

TYPES OF SHOCK LOSS

xbull X

IMPACT BDDJ

XX 1a Teloc1t7 caponent ot shock

Figure 2 - ~bine Runner Vector Diagram$ and Shock Loss Diagrams

11

2 shock loss (XX gt2g

C =sin (BimiddotAl)Let (1)sin Bi

(UlmiddotCV1)2Then shock loabull (2)- 2g

For a given gate opening C ia a constant ranging

from about 14 to 10 For a well designed wheel it is to middot

be expected that C would be approximately equal to U1V1

at rated conditions ie at point of maximum efficiency

This point will occur in the neighborhood of 3~ to 78

gate opening for moat turbines For overgate conditions

the angle A1 becomes larger so the value of C would

decrease For gate openings below rated conditions t he

angle A1 decreases and C would decrease One could expect

a fairly uniform decrease in t he value of C as the gate is

closed from t he overgate position

The velocity v1 is approximately constant for any

turbine speed since the area and rate of flow both decrease

fairly uniformly However for a given gate opening the

velocity V1 will decrease with increased turbine speed

From the foregoing comments and equation (2) the

following trends can be established

(1) For constant turbine speed the shook loss curve

will be close to parabolic in shape concave upward and

have its maximum near t he point of complete gate closure

--

12

and its minimum near the rated gate position

(2) For conatant gate opening the shook loss curve

will approximate a symmetrical parabola with its vertex

the point of minimum loas located at the rated condition

of operation (7 Pbull 79)

c Exit Loas

It can be seen from Figure 2 that the exit loss from

the turbine would be v222g if no draft tube were present

The addition of a draft tube permits the gradual reduction

of velocity by an increase in cross sectional area between

the exit of the runner and the exit from the draft tube

The exit loss and the frictional loss encountered in

the draft tube may be placed together in the expression

m va2 (3)Exit Loss ~---2g

For the ideal case of no friction in the draft tube

m is equal to the square of the ratio of the area at exit

from the runner to the area at exit from the draft tube

In an actual turbine installation however friction

will change the value of m (7 p 84-85) to somewhere

between that for the ideal case and a maximum ot 10

In the interest of maintaining a minimum exit loss

the turbine should be designed and operated so the velocity

V2 will be minimum This will occur when the discharge

13

vector is at right angles to the tangent to the runnerbull

ie the angle A2 1e ninety degree bull It ia to be expected

that this condition will be tultilled near the design con~

d1t1ons ot the ~bine

Current design praetiee 1 to have a small component

ot v2 in th$ direction of turbine rotation at rated condibull

tion$ ltS p 938)

For a constant turbine speed the d1seharg or exit

loss is ess nti lly a constant

For a constant gate opening the exit lo s curve is

aptrroximately a symmetrical pa~abola with ita vert x the

point or minimum loss located at a slightly lowe~ speed

th n the turbine rated speed (7 Pbull 79)

Chapter III

PROPOSAL OP ALlERMAlE MFTBO 0 CO TROL-A lz ~ Location 2 Control

Thua tar only practice and theoretical aspects appemiddotrbull

taining to present day turbinea have been d1acuaaed It

haa been presented that control over the ~bine ia ezerbull

oiaed b y manipulation of the wicket gatea located 11101led1bull

ately preceding the runner These gate - upon rotation

modify both the magn1tu4e and the direction ot the entering

velocit7 Moreover it has be n shown that a simultaneous

change in these two variables leads to inefficient operabull

tion by the introduction of shock loss he farther the

point of operation a from the rated conditione the more

aerioua ia the ahock loss encountered

Any attempt to better turbine pertorance at other

than rated conditione and tbne flatten the top ot the

etticieney hill8 must concentrate upon the lessening ot

the ahock loaa It 1a a aumed that 1 provement in the

scroll case gates and runners would lequ1re sueh pertecbull

tion 1n machine work and metal$ as to be prohibitively

expensive

It ie surmised that any move to elblinate eYen parbull

tially the shock loss would require separate control ovel

l$

the flow and gate exit angle Since it is improbable that

d1~ect1on could be controlled at any location other than

where the gatea are situated in current turbines it will

be assumed that guide vanes will be necessary regardlesa or the method used to control the rate of flow

The primary purpose ot th se guide vanes 1s that or control over the direction ot the incoming water They

should be free to rotate in much the same manner as ordibull

nary wicket gates in order to exercise control over th

turbine speed

If the rate ot tlov is to be controlled elsewhere it

must be modified either in the penstock or the draft tube

Devices that could be used are standard valves gates

variable orifices variable venturi sections and associated

flow regulating schemes

Alauming it were decided to locate such a device upbull

stream of the turbine it would be necessary to allow disbull

tance tor the flow picture to become reestablished prior to

entry to the turbine A contused flow making transit of

the turbine passages would only contribute additional loesbull

ea Such a distance allowance would be perbapa 20 to So

diameters (2$ Pbull 119-123) In large penstocka th1a would

repreaent a considerable distance Which from the viewbull

points ot convenience and control would be undesirable

Attempts to ascertain the effect or additional tlov

16

reduc ion at the wicket gatctsmiddot wae ade 1n the lfadraulioe middot

Laboratory of Oregon St middot te College in 1933 (20) Three

d1tterent thode ot reducins the tlow were t~ied

(l) Locking in the cloeed position pairs or wicket

gatea located opposite to eaeh o~er on the -periphery ot

the wheel

(2) Locking adjacent gates in an open position by

inserting blocks of wood between them and

()) Suocess1vely looking adjacent gates in the closed

position

The results indicated a arked reduction in both power

and efficiency when compared to the curves tor normal gate

operation However it was demonstrated that it was poae1bull

ble to ahitt the power and tfieiency curve ill relation to

turbine apeed lbis important feature will be diacussed

later

ihe main conclusion of the investigation was that conbull

trol by the conyent1onal wick t gates was auper1or to other

methode egtt control exercised at the gates the aelvebullbull

It would app$ar that the bebullt location tor flow conshy

trol would be in the draft tube since none of the objecbull

tiona prev1ously mentioned wou~d eziat there

As bas been stated previously the sole object or the

17

18

turbine is to produce power as etfic1ently as possible

The equation tor the power output of a turbine () Pbull 227)

PaWHe HP (4)55o bull bull Assuming the head 1a constant and a g te located in

the draft tube decreases bhe rate ot flow the power eu

only be increased if the etticiency increases

The ettective head Gn the turbine 1s conventionally

d r1ned as the difference between the auma ot the elevashy

tion head pressure head and velocity head at the entrance

to the turbine casing and the tailrace ($ Pbull 872)

lt ie recognized that the theoretical treatment ot

shock loss as given is highly approximate and serves only

to dictate certain trenda For example the area at xit

rom the wicket g tea CfUl be measuPed with some exactness

but there exists no guarantee that the wateP particles will

complet-ely fill the apace oz- will exit at the establiahed

g te angle The same can be said of the exit trom the

runner blades AssUIlptiona were implied which would indishy

cate that all water particles passing a given croea section

ampH traveling at the same velocity in the same direction

the e alone are autt1c1ent to show 11m1tationa in a theoretbull

1eal approach to the problem

Assume a turbine with ordinary wicket gates tor oonbull

trol compared gainst the same turbine with a gate in the

18

draft tttbe tor supplampment1ng control or the rate ot rlow

Let it also be assumed that the two turbines are opershy

ating at the same point It 1s desirable to predict relabull

tive performance of the two turbines 1 this point of

operation is such that edd7 s hook loss ot reasonable proshy

portions is present in the fir t turbine

~ tull erteot of the shock loss will be exper1 need

by- the fir t turbine

lhe second turbine will derive certain advantages 11

the gate in the draft tube is adjusted to reduce the tlov

1n the proper amount Since they vary a the square ot

the veloo1t7bull the lossabull in the aeroll case wiomiddotket gate

and runner passages will decx-ease aetet-r1ng to Figure 2 1

it can be seen that a decreased velocity v1 w-ill reduce the

eddy shock losa

The ent loss in the dJtaft tube of the second turbine

will be the sum ot the tr1ct1onal loss and the velocity

head at ex1t The velocity head dissipated will be greater

due to the closing action or the gate but the reduoed

t~ictional loss which ia a tunction ot the rate of tlow1

will partially balance this

It 1a entirely possible that the net reduction in

losses in the second turbine will lead to a greater ettibull

oiency and more power output than 4eYeloped by the first

turbine

19

In Figure 3 the plot ot power output against turbine

speed for Curv A~ represents the typical family of curvea

tor a reaction turbine Th b st sp ed is the locus ot

points connecting maximum eft1oiency at each gate opening

The operating speed is the coZUJtant turbine apeed which

passes through the point ot maximum efC1ciencr of the turbull

bine The plot of turbine efficiency against power output

for Curve A is also ahown

It the turbine with flow regulation in the dratt tube

oan demonstrate superior power and efficiency at part loads

the effect would be the same as a shifting or the power

curves toward the condition shown fop Curve B 11 Thisbull

illustrates th ultimate case of the uperpoait1on of best

and operating speeds It will be noted that the pet-form~

of the turbine ot Ourve Bu 1a better than that of CUrve

A at part loads because of ita ability to sustain a relabull

tively high etticienoy ovel a Wider range of power output

o Reguireaegts tort Test Velitication

It is desired to deterra1ne the effect on the turbine

performance b) the addition of a gate in the dratt tube

Th step in the teit will bet

(1 To determine the power output and efficiency ot

the turbine tor wicket gate settings above and below rated

conditione for a wide range ot speed

20

CURVEAbull

TURBINE SPSBD TURBID SPEKD

POIBR OOTPOl

Figure 3 - Turbine Performance Curves

21

22

(2 peat (l) with the gate installed in the drat

tube

(3) middot Converting middot all data to a constant head compare the

powere and effioiencies at the same wicket gate setting and

turbin speed tor the two cbullses

If the ddition or the gate indicates an improvement

in power output and efficiency and the powe~ curve shifts

to the right along the turbine apeed scale the advantage

ot draft tube con~ol of the flow will hav been demonshy

strated

Chapter IV

A E9J11pment

ih turbine used in this test is lJ 5 1nch Pelton

reaction turbine with a rated output ot 30 horsepower under

a head of 56 feet at a speed ot 720 reYolutiona per minute

Views of this turbine are hovn in Figures S and 6 The

turbine is installed on a concrete pad located over an open

channel in the Hydraulics Laboratory at Oregon State Colshy

lege The date of manufacture of this turbine was 1915

The water was delivered to the turbine from a sump

reservoir by two pumps operating 1n parallel Each pump 1a

an 8 inch Pelton double suction centrifugal pump witb a

rating of l$00 gallons per minute at a head ot 75 teet with

a speed ot 1175 revolutions per minute Tbe inlet tlange

ot tne turbine is $pprox1mately 18 feet above the center

line of the pump

A direct current generator was coupled to the turbine

to receive tne power d veloped as shown in Figures 4 and 7 The generator is a Spr gue Electrodynamometer rated at SS horsepower with a speed range of 7$0 to l$00 revolut1one

per minute The classification is type LO 26A 2)0 volta

Figure 5 - View of Test Turbine

Figure 6 ~ View of Test Turbine

and 149 amperes lbe generator ti ld was aepar tely

excited using direct current from a motor g n r tor ampt

(l$ p 4~8)

The power output of the generator waa dissipated in

the water rheostat (3 p 488-489) shown in Figures 9 and

10 The galvanized tank contain d water ot variable d pth

on an electrode ot cast iron m aauring 1bull x 1 x 1

In the initial installation of the turbine it was

intended that the power output should be measured with a

Prony brak bull For th purpoa68 or this teat it was decided

that the brake was too instable and the generator was

substituted The platform for raising the generator the

nee asary two teet for alignment was built out of available

material In this case heavy laminated wood blocks reiashy

torced with other timbers were used and bolted through the

concrete deck (11 Pbull 36-$7)

Due to the light concrete deck the lack ot mas in

the platform and the slight misalignment in the flexible

coupling ao e vibration waa encountered It seemed to

ncr aae linearly to a maximum at the speed of bout 750

revolutions per minute Above this speed no vibPation was

noticeable The vibration waa not se~ere and does not

appear to have materially affected the test results

26

B Intrumentat1on ~ eaeur1ng Devices

The pressure head at inlet to the turbine vaa meaave4

bymeane ot two )6 inch waterbullmeroury manometerbull connected

in series as shown in Figure 8

The terminal voltage ot the generator vas meaeured by

a laboratory voltDleter with a range to )00 yolta and callbull

brated to within 15 Yolta

The armature current bull and hence the line current was

measured by a laboratory ammeter with a range to 150 amperea

and callbrated to w1 thin o 7S amperes

Tae rate ot tlow was established by weight and time

meaeurementa The weighing ank has a capacity ot 121 000

poundsJ the weight belng indicated by Toledo direct reading

scales Timing was done with a hand atop watch with clivibull

aion ot 02 second

he ~ater level in the tailrace was dete~1ned by a

hook gauge lhie was read to the nearest 001 toot

The turbine and generator speeds were eaaured by a

hand tachometer The technique of almost cont1nuoua readbull

ings of the speed gave an error ot no more than 5 revolubull

tiona per minute

c Operational Procedure

Atter the water level in the aump was checked to

insure an adequate auppl7 the puapa were primed and

27

Figure 7 - Test Generator and Plattorm

Figure middot8- Instrument Board and Field Rheostat

28

started After venting they were valved for operation 1n

parallel

The motor generator set was started to supply the

field current and the circuit breaker was closed Water

wa added to the water rheostat to the level shown in

Figure 10 ~ field current wae minimized by cutting in

all the f ield resistance in the field rheostat of Figure 8

The l2 inch gate valve shown in Figures 5 and 6 waa

slowly opened and the turbine and generator brought up to

speed The 12 inch gat valve and turbine were vented and

the pumps were checked to insure neither had lost ita prime

lhe water rheostat offers very steady load 1f the

water level is essentially constant and the water temperabull

ture 1a fixed () p 488~89) In order to maintain this

constant temperature it was decided not to circulate the

water in the rheostat but rather to allow the water to

boil thua achieving the desired result A standing wave

was set up on the face ot the electrode by the boiling

action but a atable load was eatablished except at very

low water leYels where th11 agitation led to fluctuationa

in the line current

After putting the turbine and generator on the line

maximum power was dissipated in the rheostat by redueing

the turbine speed to between oSO and Soo revolutions per

minute Salt vas added to the rheoetat wat r to increasemiddot

29

Figure 9 - View of Water Rheostat

Figure 10 - View of Water Rheostat

Separate Field ExcitationFrom Motor-Generator set Compound Water-Mercury

---shy

re Manometer

I Q)

~ 0

~

Book Gauge

Open Channel

I

Slap Reservoir

Figure 11 - Wat~r Flow Diagram and Electrical Layout

31

waiting pe~iod ot perhaps an h~ followed

while the boiling point or the water wbulls reacbe4 During

this ti+ne the manometer was vented end eheoked electrical

measur1ng 1nstlUments were connected end the hook gauge was

adjusted tor elevation

It required about two- houtte tor the generator to reach

its normal operating tempe-ratu~e_ After the water in the

rheostat and generator had reached their operating temperabull

turea it was possible to begin the taking of data

The only vaPiable which was controlled wee the turbineshy

generator speed However the upper l1ut1t of safe line

current was slightly over 100 ampJilPampPes and the eireuit

breaker would open when the current reached lOS ~ere bull

Control was exercised by means ot regulating the water

level and salt 1n the water rheo tat and the res1stsnoe of

the tield rheost t~

The etfeet ot each type ot regulation on the three

variables is shown below

Volta Aaperebull Speed

Inc Dec Inc Dee~ Inc Dec

Wa~e1 Level Inc Dec~ X

X X X X

X

Salt Concentration

Inc Dec X

X X X X

X

field Resistance

Inc Dec

X X

X X

X X

32

Jlot all methods gave the ame amount ot change in a

given variable and a period of experiment and trial led to

the following scheme starting the rune with the lowest

turbine speed the water level was high with a high amount

ot salt and the field resistance was cut completely out

Aa it became necessary to increase the speed tor each

aucceasive run either cutting in t he field resistance

decreasing the salt concentration or lowering the Vater

level would produce the desired result However decreasbull

1ng the salt concentration had to be done Without a net

gain in water which led to a tluahing procedure that was

not particularly good because cold water was introduced

which required time to heat to the boiling point Cutting

1n additional field resistance was a good method but th1a

increased the amperage possibly to the point of opening

the circuit breaker Lowering the water level was aatiashy

factol1 until the level got too low causing the current

fluctuation previously mentioned Actually it turned out

that a combination of lowering the water level and cutting

field resistance in would carry the speed from ita minimum

to 1ts maximum value it the proper choice were made each

time the speed waa to be changed At the conclusion of

each aet of runs at a high speed the water level would be

low and the field resistance high

33

TURBINE

PAD AND DECK

TAILRACE

WATER SURFACamp

CONCRETE

DRAFT TU1B INSERTS

7 5( DRAFr TUBE

FLltJI ARIA

5~ DRAFT TUBE

FLOI ARSA

Figure 12 - Sketch of Draft Tube and Test Inserts

34

Figure 13 - View of Draft Tube Insert

Figure 14 - View of Draft Tube Insert

D c __ ~s_middot hedu_le of

A number was assigned to each run The fi~st number

applies to the draft tube tlow areas

1 bull 100~ flow area or 0~ oonatriction

2 - 7S tlow area or 2$ conatr1ct1on

3 SoC flow area or so~ constriction

The second number refers to the wicket gate openings

9 over gate opening

6 bull intermediate gate opening

4 bull one h lt gate opening

The third number 14entif1ea the location of the particular

1Wl in a set ot rona made at a given dratt tube tlow area

and wicket gate opening

fnua run number 1bull4bull10 would identity this as the

tenth run ot a set made at halt gate with 75 ot the draft

tube t1ow area

Rune w re made tor a g1yen dratt tube condition

Firat tor tull 41-aft tube flow area seta ot rune were

made for the overgate halt gate and intermediate gate

conditione An insert was placed in t he draft tube and

rune based on the same gate conditions were made tor the

7S~ draft tube flow area case The insert was then changed

to allow only $~ draft tube flow area

The inserts are sketched 1n Figure 12 and photographed

ln Flgurea 13 and 14 They oonaisted of circula~ segments

36

or l2 ineh plywood mount 4 on wooden legs 10 inches high

The 1nse7te were placed in position and secured by th use

ot a-clamps on the legs and the outside ot the bottom of

the draft tube The obvious disadvantage to this method

waa the neoeasity tor draining the water from the tailrace

tor a change ot 1naert The advantage vas of course the

simplicity ot design and construction

Chapter V

DATA-A Original Data

The normal data-taking crew consisted or two men

Assuming adjustments having been made to secure a certain

turbine speed (aee section on Operational Procedure) one

man would take semi-continuous speed readings with the hand

tachometer until a state or rotational equilibrium was

reached This could be only a period or two minutes up to

ten or tifteen minutes As soon as steady speed was

assured the data taking would begin The second man went

to the weighing tank Where a minimum ot three weighingamp

were made The requirement was to get three consecutive

readings such that the ditterence between tbe smallest and

largest time did not exceed 04 seconds The time to

collect a given weight ot water was then assumed to be the

arithmetic average of the three times He then went to the

hook gauge determined the hook elevation and then

recorded the data on the data sheets The first man meanshy

while had taken readings of the line voltage line current

and manometers and checked the turbine speed by multiple

readings During the length of the run all values were

38

checked to determine mean values for recording

The minimum length of one run was about five minutes

If one or more measure ants tended to drift during the run

all values wer discarded and a new run began as soon aa

qu111br1um was stabl1shedo

B -0-al_e_u_l_a_t--d Data

The h d on the tu~bine 1 defined by

($)

The maxtmwm velocity V4 was equal to about o8 tampet per

secon4 which makes it a negligible quantity when converted

into velocity head

An engineerbulla level was used to deterine the d1ffePshy

ence 1n elevation between the compound water-mercury manoshy

meter and the hook gauge Using this value the equation

for turbine bead becomes

where z4 is the hook gauge reading

The rate of flow 1 cent

w weight or water collected average time to collect

The inlet velocity v1 vas calculated by dividing the

weight rate or flow by the specific weight of water and the

)9

area ot ~e inlet pipe This was equivalent to dividing

the weight rate of flow by 490 Then the power input to the turbine is equal to

WHpin rri

10 (6)

Also

(P ~ut) Turbine

(P out) + Generator

(P lost) Generator

The power output of the generator is simplJ the

produot ot the terminal voltage and the armature (line)

curPent The power lost in the generator can be subdivided

into copper losses and stray power losses lo evaluate

these cunes based on losses of an identical generator

11leampsured by the Department ot Mechanical Engineering were

used The loss curves are reppoduced in part in Figures

15 and 16

Determination ot generator losses proceeds as tollowau

(1) From Figure 15 detem1ne the vo1tage drop in the

armature circuit using the temperatures of 1220 F and the

meaaured current

(2) The induced voltage is t~e sum of the terminal

voltage and the voltage drop 1n the armature circuit

() Entering the induced voltage and the turbine speed

into Figure 16 the stray power loss can be determined

(4) The copper lose can be evaluated from Figure 1$

using the measured current and the temperatlll-e of 1220 P

40

25 ~------~--------~--------~------~

U) -U) - 20

f-4 ~

-~ -gt 0

0

VOLTAGE DROP

~ - i -

- bullbullbull bull - -middot-middot -+ ~- + -t--+ ~ - ~ middotbull ~-~ middott- -+----- _ -4 middotmiddot- --~-+-t---r~~ ~--+t-t- - ---t-c-++~-ulf--

0 50 75 100

Figure 15 - Curves of Generator Voltage Drop and Copper Loss

41

1200

1000

800

600

800

0

0

~-

middot--~ 1shy --1 + bull l

100

I -

150 200

IIDOOED VOLTAGB (VOLTS)

Figure 16 - Curves of Generator Stray Power Loss

_ j

-bullshy -L---- shy middot -shy

250

- r

42

(5) The generator los os equal the sum of the eopp r

loss and stray power loss

~e efficiency or the turbine is taken as

etticiency u e =P out (8)Pin

~ample pound Determ1n1gg turbine Power Output

The following data are taken trom that ot Run 1-9-1

Line voltage 1040 volts Line current 870 amperesSpeed 355 revolutions per minute

The induced voltage 1a determined as follows

Line voltage 1040

Voltage drop 90 using Figure 15 with line current of 870 amperes and temperature ot 122 degrees)

Induced Toltage 1130 volta

The power output of the turbine is determined as follows

Generator output 90$0 (line voltage z line current)

Oopper loss 7 (using Figure 15 with line current of 870 amperes and temperatUe or 122 degrees)

Stray power lose 470 (using Figure 16 with speed ot 355 revolutions per miDUte and induced voltage or 1130 volts)

Turbine power output 9527 vatta

or turbine power output 1s 12z2 horsepower

43

The conversion of the calculated data to a constant

head is based on the conventional assumption of constant

efficiency regardless of turbine head For a constant head

ot 81 teet a purely arbitrary figure the tollowing relashy

tionships are ass1lJiled to be true

I ____L (9) (i)l72

(10)

For these two values the specific a peed may be combull

putedt

N t Jt VPt (11)8 243

Chapter VI

~RESULTS

A -Pr_e_ae_n_t_a_t_t_o~n g Reaultbull

Graphical presentation ot the results ot this te1t

are given as follows

Figure 17 -Turbine characteristics with 100~ dratt

tuba 1low area

Figure 18 - Turbine characteristics with 7S dratt

tube tlow area

Figure 19 bull Comparison ot power and etticiency at

over gate conditions between 100 and

75~ draft tube flow area

Figure 20 bull COZQparison of power and ettic1ency at

halt gate conditions between 100~ and

7S~ draft tube flow area

Figure 21 bull Comparison of power and etticiency at

over gate condition between 100~ and

So dratt tube tlow area

Figure 22 - Comparison in variation ot apec1t1c

speed between 100 and 75~ dratt tube

tlow area

50

45

20

-bull - 1--shy40

bull J-~ 30

~ ex

~ 20

~~ ~ -)q

I

~ - _

- -

10~ OF DRAFT TUBE FL(Jif AREA

CONSTANT HEAD OF 8l FEST10

POIER OUTPUT EFFICIENCY SPECIFIC SPEED

0 ~--------------_--------~------~------~ 400 600 800 1000 1200 1400

TURBINE SPEED (RPM)

Figure 17 - Turbine Char~cteristics with 100 Draft Tube Flow Area

50

46

-bulllle

~ 7 ~ OF DRAFt TUBE FLOW AREA

0 -~~-rl C05STAMT BEAD OF 81 mET 1J~

POIER OOTPUT ---+- ---o ~_H EFFICIDCY ~ I shy

bull ql SPECIFIC SPEKD - ~ -

bull ~ J 10 L rmiddotr- r- -

bullz- I

~~ 30 ~~--~----~~-

20 ~ ~ middot-shy

26

~~ 25

~0 ~r-----i (

Tbull -bullshy

400 600 800 1000 1200 1400

TURBINE SPEED (R PK )

Figure 18 -Turbine Characteristics with 75 Draft Tube Flow Area

47

EFFICIENCY 60

1-----shy

-~ 50~--~--~~-~middot middot middot middot r~-~----~~~~---4~-r~-~~gtt

II

POWER~ J ~ bull bull

u I

sH

40~------+-------+---- -~~--~~-~~~~

~----~rl 1 bull

I

I

0~--------------~------_------~--------

~ -OVER GATE CONDITION

COIJSTANT HEAD OF 81 FEET

0 o 10~ DRAFt TUBE

_-- _ 7~ DRAFT TUBamp FLON AREA II

10_~-----+--------r-------r----~~

400 600 800 1000 1200 1400

TURBINE SPEED (RPM)

Figure 19 middot - Comparison between 75 and 100 Draft Tube Flow Areas of Power and Efficiency at Over Gate Conshydition

48

t

bull --4 r ~- ~ middot~

70 1-----------+-~~~~~+middot ~ ~~ middot middot -~~--~~--------~~----~-+1

-~-

Atbull bull

lla-

60

amp0

40

20

10

oampOO

t _ - - ~-+- - -~-

l2 GATB COJIDITIOJJ

COJISTABT HJW) OF 81 JBET

o 0 lOQ( DRAFl TUB8 FLOI AREA

e-- - e 75 DRAFT TUBE FLOW AREA

800 1000

- r-

~

TURBIbull SPBIID (RPII)

Figure 20 - Comparison between 75 and 100 Draft Tube Flow Areas of Power and Efficiency at Half Gate Conshydition

49

60

50

-40

bull 30

IIQbull

20

10

0

400

- t - ~

EFFICIENCY

_J bull - bull bull

~ r r middot t -+ shy L -t -

OVER GAD COliDITIOI

CONSTABT BEAD OF 8l FBB

o o 10~ DRAFt TUBE FLOI ADA middot--- 5~ DRAF TUBE FLQPi AREA

600 800 1000 1200

Figure 21 -Comparison between 50~ and 100~ Draft Tube Flow Areas of Power and Efficiency at Ove~ Gate Conshydition

50

25

20

15

10

0

Figure 22

~- T -4 -t- -l --~-

t-~ I

middot --~- t ~---- _ __ _ + --

----~- --r-- --

~-=J-~-=-~ -==~ _ ~- -- ---f---1 - shy

CONSTANT HEAD OF 81 FEBT

o--o 1~ DRAFT TUBE FLltll AREA

75C DRMT TUBK FLCIJ AREAmiddot--middot-middot 600 800 1000

TURBINE SPEED (RPK)

Comparison of Specific Speeds for 75 and 100 Draft Tube Flow Areas

51

B Discussion 2 Result

Consideration of Figures 17 and 18 indicates the

overall eftioi ncy pattern or hill is significantly or

rounded for the 7$~ flow area than for the 100~ flow area

bia implies a greateP efficiency is possible at speeds

leas than or greater than design speed with an insert in

the draft tube However the muilDum efficiency is lemiddotas

Direct comparison at over gate conditions is made in

Figure 19 ~e same general trend is noted tor both the

etticiency and power curves for the 7$~ flow area case

The eurves show higher values at overspeed than do the

correaponding cWvea for the 100 flow area case It ia

not clear whether the curves have been shifted by the dratt

tube constriction or whether the curves simply bulge past

the normal curves at both overspeed and underspeed condishy

tions The power curves apparently peak near the aeme

point bullalthough maximum power is still obtained with the

normal draft tube area

For the comparison at halt gate operation shown in

Figure 20 a general improvement has apparently been made

by restriction of the draft tube flow area At every speed

the etticienoy and the power is greater for the restricted

tlow case The two ett1o1ency curves and two power curvea

are practically parallel throughout the speed range ot

teat

As the flou aroa i e decreased still farther a s1gn1

ticant change appears Reterr1ng to Figllle 211 tor the $0

flow area curves it a obvious that exit losses have

become excessive at the overgate condition because the

efficiency and power are everywhere leas than tor the case

of normal draf t tube area

Earlier it was pointed out t hat 1t the r esult s 1nd1bull

eated an increase in both power and ef tieiency- t hen it

could be assumed tha t the additional los s i ntroduced with

the draft tube insert is less than the diminished losses

due to leas shock losa and water passage losses For the

places where both the efficiency and power have been

increased we can assume that the insert has improved turshy

bine performance

For the places where the power haa been decreased

nothing can be said as to the elimination of ampbock loss

because the new lose present with the drat tube insert has

overshadowed any gains in eftecti Ve head upatJ-eam of the

insert

Near the peak of the efficiency hill howeve~ it may

be pointed out t hat shock loaa ie a minimum with a normal

draft tube and the insert merely adds an additional loss

with the resultant decrease in maximum efficiency tor the

7$~ flow area case

Perhaps the most s1gn1ticant set of eurves is shown aa

53

Figure 22 In this graph values of specific speed tor the

75 and 100~ flow area cases for both over gate and one

halt gate openings are plotted against turbine speed At

every speed and both gate openings the value ot specific

speed for th 75~ flow area case is greater than that for

the 100 t1ow area ease

Since the head is a constant for both situations this

may be interpreted in either of two ways trom equation

(11)

(1) For the same turbine apeed restriction of the

draft tube t1ow area resulted in greater turbine power

(2) For the same power amputput the turbine with 75~

draft tube flow area operated at a greater speed than did

the one with 100 flow area

Since the required diameter of a turbine varies

inversely with the speed the second interpretation could

be stated such that a smaller turbine could be used to

develop the same power output

Whether viewed trom the aspect of increased power

greater speed or reduced size the performance of the turshy

bine with reduced draft tube flow area is superior to that

with the nolmal flow are in the draft tube

The curve of specmiddotific speed versus turbine speed for

the so draft tube flow area case at over gate cond1t1ona

was not included in Figure 22 This curve lies below that

for the 100~ flow area c se at all speeds

In elaboration ot the second interpretation of Figure

22 attention is directed to the relative magnitudes ot

increased apee1f1c speed tor the two gate openings Assumbull

ing that the increase in specific speed implies a shift ot

the power curve to the right along the turbine speed scale

the power curve would be shifted more tor tbe halt gate

opening than tor the over gate opening

It thia trend could be extrapolated to the other gate

openings the tendency can be seen tor the line ot beat

speed to rotate toward the line of the operating speed as

illustrated in FigtU-e ) The advantage of this has already

been discussed

This particular turbine has a low specific speed tor a

reaction turbine Aa the rated value of apecitic apeed tor

reaction turbines increases the line ot beat speed departs

even more radically from the line of operating bullpeed It a

test similar to this were conducted on a reaction turbine

ot gleater specific speed it is pJobable t hat the rotation

ot the line of beat apeed would become more p~onounced

The scheme used in th1a teat had two obvious dr wbull

backs The first was the decision to leave all the wicket

gamiddottes installed tor all conditions ot the draft tube

These gates predominated in control of the tlow The

inserts added to the draft tube merely acted as auxiliary

55

contrGla

The aecond drawback was the choice or device to place

in the draft tube The reasons foll selection of this type

of device have been previously mentioned It is to be

anticipated that adaptation ot dratt tube flow control

would result 1n a better device for an actual turbine

installation Such apparatus might take the form of a

pneumatic bladder or a h7drau11oally operated variable

venturi section in the draft tube It is conceivable that

the gate as used in this test might be adapted also

Chapter VII

OONCLtJSIOfS

From the results of this test the following eonolubull

e1ona aa to the effect ot a variable draft tube flow area

on the performance or a r action turbine may be drawn

(1) The effect ot a variable draft tube tlow area 1a

generally favorable upon the operat1Gn ot a reaction turbull

bine because or the tendency tor the line or beat speed to

rotate toward the line ot operation This resulte in

better performance of the turbine at partbullloads

(2) he etf1o1ency eh111 tor the turbine beeomaa JDore

tlat at the top leading to a smaller max1JilWD effic1enc7

but e reater etticieney at other pointe of operation with

the insertion ot an auxiliary control ror the rate ot tlov

in the draft tube

(3) The power output of the turbine will increase at

over speed over gate conditione as well a at part gate

conditions with the proper amount or draft tube eonatr1cbull

tion or flow

(4) It is possible to eliminate at least partially

eddy type shock loss by tho introduction ot flow control

in the draft tube

BIBLIOGRAPBl

1 Addison Herbert A treatise on applied h-draul1cs New York Wiley 1954 724 Pbull

2 Allen o M and I A Winter middot Co111parative testa on experimental draft tubes Tranaact1ons ot the American ociety ot Civil Engineers 87t893bull970 1924

3 Barrows a E Water power engineering 3d ed ew York McGraw-Bill 1943 791 Pbull

Bovet G A Modern trenda in hydraulic turbine design4middot in Europe Tranaactions of the American Society ot Mechanical Engineera 75975bull993 1953bull

s Oreager William P and Joel D Justin Hydroelectrichandbook 2d ed New York Wiley 19$0 1151 Pbull

6 Daily Jamea w Hydraulic machinery Int Hunter Rouses Engineering hydraulics Hew York Wiley 19$0 p 8$8bull99

Daughertybull Robert L Bydraulie turbines ew Yorkbull7middot MoGrav-Hlll 1920 281 Pbull

8 Daugherty Robert L Inveat1gat1on of tne performance ot a reaction turbine ~anaactiona or the American Society ot Civil Engineers 7811270bull1304 1915

9 Davie L M Model and prototype testa Int Trend in hydraulle turbine practice symposium lranaactions ot the American Society ot Civil Engineers 1o63S3middot368 1941

lfJ Doland James J Hydro power engineering Hew Yorkbull Ronald 1954 209 Pbull

11 Gandy Theodore s and Elmer c Schacht Direct curshyrent motor and generator troubles operation and repair New York McGraw-Bill 1911 293 Pbull

12 Gibaon Arnold H Hydraulics and ita applications5th ed London Constable 1952 813 Pbull

58

13 Button s P Component loases in Kaplan turbinebull and The prediction of efficiency from model tests Probull coedings of the Institution or Mechanical Engineers168743-762 1954

14 Knapp R T~ Oavit t1on mechanics and its relation to the d sign or hydraulic equip ent Proceedings or tne Institution ot Mechanical Engineers 166150bull16) 1952

15 Langsdorf Alexander s Principles of direct curHnt mach1nee 5th ed New York r~cGrawbullH1ll 1940 746 Pbull

16 Lsrner Chester w Characteristica of modern hydraubull lie turbines Trans e~ions of the ~~erican Society ot Civil Engineers 66306-386 1910

17 Linsley Ray K Jr and Jobulleph B Franzin1 Eleshyments of hydraulic enginebullring New York McGrawshyBill 19$5 $82 Pbull

18 Mead Daniel w Hydraulic machinery llev York McGraw-Hill 1933 396 Pbull

19 ead Daniel w Water power engineering New York McGrawbullRill 191S 843 Pbull

20 Mockmore Charles A Part gate operation at water turbines Corvallis Oregon State College Department ot Civil Engineering 1933 11 numb leaves (Unpubshylshed typescript)

21 Mockmore Oharles A Flow characteristics in elbow dratt tubes Transactions of the Amez-ican Society ot Civil Engineers 103402middot464bull 1938

22 Moody L F Hydraulic machinery In c v Davis Handbook ot applied hydraulics New York McGrawshyHlll 1942 1082 Pbull

2) Ptau At-nold Hydrbullulie turbine handbook ld ed Milwaukee AllisbullOhalmers ManufactUIing Company 1948 70 Pbull

RheingalUI w J Recent developments in Francis turshybines Mechanical Engineering 74189-196 1952

25 Russell George E Hydraulica 5th ed New York Henry Holt 1942 466 Pbull

26 Safford A and E P- Hamilton American mixed tlow turbine and ita setting Tranampactions or the Amerieal Society of Civil Engineers 851237bull1)56 1922

27 bull Spannhake W1lhe1Dh Problems or modern pump and tur b1ne design Transactions of the American Society of Mechanical Engineers 56e22$-248 1934bull

28 Sutherlandraquo R A Better ethod or representing and middot tudying water turbine performance ~ansaetions ot thmiddote American Society of Mechanical Engineers 68t675bull 686 1946

29 Teats ot five models or draft tubes tor turbines Engineering News-Record Pbull 182-184 Aug 2 1923

30 White w M American hydztaulic turbines Mechanical Engineering S2t390bull39S 1930bull

31 White w M lhe hydraucGne rega1ner1 its developmentand appl1eat1ons 1n hydroelectric plants Meohanlobulll Engineering 43t37Sbull380 1921 middot

32 Winter I A Economic principlebull in designbull Int Trend in hydraulic urbin practice bull a ampoeiumTranaaot1ona ot the American Society ot Civil Engineerslo6332bull3S2 1941

33 Wiel1cenua G F Fluid mechan1ca or turbo-machineryNev York McGraw-Hill 1947 613 Pbull

APPENDICES

c

Appendix A

NOATIOB

A Angle between the absolute velocity vector and the tangent to the rwmer Subscripts 1 and 2 refel to entrance and exit ot the runner blade

B Angle between the relative 1elooity vector and the tangent to the rwmer Subscripta 1 and 2 refer to entrance and ezit or the runner blade

Angle between the tangent to the runner blade tip and the tangent to the runnel- Subscripts 1 and 2 reter to entrance and exit of the rt1rmer bladebull

Blade angle-gate opening conetant defined by equation (1)

e 09erall efficiency

g Gravitational acceleration assumed constant at 322 teet per second per second bull

H Turbine head detined by equation ($)

m Exit loss coeft1e1ent

Turbine speed expressed in revolutions per minute

Turbine speed under a constant head of 81 teet

specitic apeed of the turbine under a constant head ot 81 teet

p Power output in horsepower ot the tvbine

Power output of the turbine Ulder a constant head ot Sl teet

Pl- Pressure head at entrance to the tUlb1new

l1 Peripheral velocity ot the runneP Subacr1pta 1 and 2 refer to entrance and exit ot the JUnllampr blade

62

v Relative velocity reaulting trom the combination ot the absolute water velocity V and the runner periphshyeral velocity u Subscripts 1 and 2 refer to entrance and exit ot the runner blade

v] Relative velocity vector necessary to produce a tanbull gential entry into the runner blades

V Absolute water velocity Subscripts l and 2 refer to entrano and exit ot the runner blade

v2 Velocity head Subscripts 1 and 4 reter to the ~8 entrance to the turbine and the tail~ace wate~

w Unit weight ot water assumed constant at 624 pounda per cubic toot

V Weight rate ot flow in pounds per aeooncl

XX Velocity component ot ahook See Figule 2

Z Elevation head Subscripts 1 and 4 reter to entrance to the turbine and the taibace water surfacebull

Appendix B ORIGINAL DATA-Run

lfwnber

0-4-1 0-4-2 0-4-3 o-4-4 o-4-S o-4-6 0-4-7 0-4-8 0-4-9o-4-lo o-4-11 o-4-12 0-4-13

o-6-1 o-6-2 06-3 o-6-4o-6middotS o-6-6 o-6-7 o-6-8 0-6-9 o--6-lo o-6-11

Speed

rmiddot2middotbullmiddot(1)

336 38$ 451 S$9 620 669 6lt)$ 120 787 860 932

102imiddot109 bull

352 355 443middot 543middot 620 654AJs32

911 1001 1111

~essure Head rt (2)

410 410 416 426 431 43-7 439 44-9 452 467 482 soo $1 bull $

350 351 35middot7 )66 37-9 37-9 392 41 bull 3 43middot3 460 489

Elevation Bead

fjj $7 $7 $7 $7 $7 $7 51 57 5-15858 $8 58 56 56 $6565656 51 575As5a

Velocit Head

flj 07 07 07 06 06 06 06 os 05 os0404 03

09 09 oa o8 o8 os 07 07 06 o~o

Total Head rt ($)

47middot4 4A44 o 489 49-4 soo $02 $11 $14 $29 5imiddot45 2 576

41 bull $ 416 421 430 44middot3 44middot3 456 47-7 496 523551

Plow

lbtjec

326 324middot317 311 306 30029middot28 middotmiddot middot 386 275middot260 240 218

359 36~35 bull 349 345middot 339 330 318 300 273 240

Line Potential

vyqjbull 1060 1220 ~-0o 1920 2150 2000 2$60 2000 1940 18)015io11 o

1000 1100 139bull5 1760 1925 16$0 1620 1610 1540 1330 870

Line Current

amlscs 960 900 830 740 730655 70bull 0 530 660 600 5imiddot54 6 )60

982 930 860 780 ~3-545

79-5 74-5 670 560 370

P

Appendix B ORIGINAL DATA (Continued)

Run Number

Speed

Pbulltmiddotbullmiddot )

leasure Head ft(2

Elevation Head tt(J)

Velocity He-dfmiddotj

Total Bead tt($

Flow

lbstsec( )

Line Potential vo~ta( )

Line Current

amjs (sect

0bulllt)-1 0-9-2

3ll6 398

28o ~~1

$6 56

1o 10

346 347

390 365

1ooo 1190

aao 835

0-9-3 0-9-4 o-9-S

472 565 632

292 305 312

$6 s6 56

10 o9 o9

)$8 J7~o 37~7

381376 37o

1)6614oo 141o

820 ass ass o-9-6 0-9-7 0-9-8 o-9-9 0middot9-10

680 120 762 844 920

)24337346 366 390

56 $6 56 57 $7

09 os o8 oa 07

)89401 410 431454

367~ 357348 34o 322

1400 1J6o l36o 1310 1170

843 820 7957So 67~0

0-9-ll 0-912

1001 1100

41 bull 7 45-3

s 7 6~0

06 os 480 $18

299 268

980 65$

560 36~5

1-4-1 1-4-21-4-l1-4shy1-4-5 1-4-6 l-4-7 1 4-8 1-4-9 1-4-10 1middot4-ll 1-4bull12

354middot452 562 62q 674shy102 752 760- 863 932

1022 1100-

)82389 4014oa 416 41--7 423 428 44-2 45-7 486 49-2

51S757 51 5-7 5middot15zs sa $8 58 59

07 07 06 06 06 06 06 os o bull o 04 o J

446 45-)46middot4 471 ti7-9480 q86 491505 $19 548 55-4

)28 320 311 306 300 295 291 286 269 2582iimiddot21 bull

1080 14Lo 1550 153-5 1470 141-0 1385 1310 1310 1230 1120 855

970855 875 91-0 94~0 975 966 995 860 77-S 610 4fo

0 ~

Appendix B ORIGINAL DATA (Contirmed)-Run Speed Pressure Elevation Velocity Total Flow Line Line

Number Head Head Head had Potential Current rtjjmbull t~ bttec vyfs am~a12) ( ) ti fli 8

1-6-l $6 33$ $6 0bull9 400 364 1100 93 0 1-6-2 41 34laquo2 $6 oa 406 JS7middot iios a5s l-6-3 500 3~0 5bull6 os 356 1 1 o aos 41middot~1-6~4 35bull4 5-6 oa 41middot 352 16~0 82 0 5~1-6-5 5 bull 36_2 Sbull6 08 42bull6 349middot 161 ~ 0 86~0 1-6-6 622 366 $6 oe 43bull0 345middot 158 0 88~$ 16-A 649bull 37bull1 56 os 43-S 342middot 1570 895 1~- 386 57 07 46-0 192 ) 125A44 333middot 1-6-9 3) 404 5middot1 07 468 317 1620 675 1610 911 42-4 5-7 o6 48-7 298 168 0 61 0 1-6-11 999 451 56 os Sl ll 276 ~2-0 530 1-612 1115 485 58 04 54middot7 238 90 )3 0

1middot9-l 355 279 56 10 )45 385 1040 870 1-9-2 399 28J $6 10 )49 38$ 1140 86 5 l-9-3 ~ ao 291 56 ~0 35middot1 J8J_ JJ6o 815 1bull9-4 579 303 56 09 )68 375middot J4JO 830 l-9bullS 40- 313 )6 09 31middot8 370- 1460 82~0 1-9bull6 679 2) 56 09 3 bull8 364middot 1670 710 l-9-7 682 319 56 o9 384 ) 62 1460 79 5 l-9-8 724 33middot5 56 o8 399 3$6 bull 1480 76 -5 1-9-9 762 34middot3 $6 0 bull 8 407 )48 14910 13middotS 1-9-10 833middot )60 5middot7 os 42$ 339 144$ 686 1-9-ll 926 39middot1 5-7 07 455 318 1290 600 1-9-12 1000 41middot3 0-6 476 298 1115 510$ ~ 1middot9-13 1105 452 s o4 $14 2$6 710 )10

~

Appendix Bt ORIGDIAL J (Continued)

Run Speed Pressure Elevation Velocity Total Plow Line Line Number Head ltead Head jlamp$d P()ten~ibulll Current

r~~~m ft ft lbs~seo voltattj rgj twimiddot t 1 t2gt lt3 ou t ( rt

2-9-1 384 289 S 6 10 35 5 1400 1170 810 2-9-2 443middot 29$ $6 ltimiddot9 360 379middot 11(0 87$ 2-9-J 536 30bull 3 sc 09 )68 374middot 1)40 84 bull) 2-9-4 571 306 $6 09 3~1 372 120bull 0 955 2-9-5 623 316 S6 09 J l )6S UJSo 77$ 2bull9-6 669 327 S6 09 )92 )61 1240 905 2-9bull7 712 )39 56 os 40-3 351 12(0 86 bull0 2-9-8 ~5$~ J48 56 oa 412 348 1290 81 bull ) 2-9-9 04 )63 56 oa 42-7 339 12ltJO 76$ 2middotmiddot9-10 8$2 376 5middot1 07 440 33~- ~ o 710 2-9-11 955 394 5-1 o6 457 300 1100 506 2middot9-12 1000 421 $7 06 48middoti 295 1020 $18 2-9bull13 110~ 463 56 05 $2 267 620 3~0

oshy0

Appendix Gt CALCULATED DAgA

Turbine Run Generator Generator Turbine Turbine Efficiency Turbine Turbine Specit1c

Number OutputKWlt21

Loa~Jes KWlol

Outut K bull (H)

Input RP 12)

middot Percentlt13gt

Speed r~Jmiddot(

0ltput HP ~1

Speed r-m

( 6) middot

o-4-1 0middot4-2 0-4-3 0-4-4 0-4-5 0-4-6 O-qmiddot7o-4-8o-4-9 0-4bull10 0-4-11 o-4-12

1018 1o9a 1220 1)62J40214oa1J4oo 1357 1320 1164 997 718

046 o59 071 092 096 1071oo 134 104 100 109 107

14261sso 17)01948 2008 20322011 1999 19 09 1708 14-84 11o6

281279 27-7 276 215 273271 268 268 26h 258 24-5

soa 555 62$ 705 7)1145 742 74-6714645 51s 45-1

440 sos 585 720 195 sso sao 9$$ 985

1065 1135middot 1230

318 357 319 416 422 419412 39middot9 378 324 260 191

102 12bull4 148 191 21bull 3 22o 233 249 24924middot9 238 221

0-4middot13 418 104 699 228 306 1300 117 18)

o-6-1 982 045 1376 271 $08 496 376 124 o-6-2 o-6-3 G-6-4o-6-5 0-6-6

1023 1200 13 73 J415 139h

051 0middot66 oaa ()bull 96 088

14-39 1696 1958 2026 1986

276 27middot4 273 278 274

$20 61 8 717 7)0726

q95615745 8)5685

390 ll5middot3 sos soo 490

127 170 218 243 2$$

o-6-7 o-6-8 o-6-9o-6-lo

1288 1199 1032 7-45

o9o 094 09$ 096

1846 1733 1511 1128

274 276 271 260

67S 629559 43middot4

980 1085 1165 1245shy

436 )83316 21bull 7

266 276 270 239

0-6-11 322 1oo 566 2141 2JS 1350 101 177 0 --4

Appendix C CALCULATED DAlA ( Continued)-Run

Number Generator Generator

Out2ut Losaes xw LW- 12gt (lO)

Turbine Out2ut

ltPlJ

Turbine Inat lfP Jig)

Etpound1e1ency

PireentDl

Turbine Sed x-~m( 1

Turbine OutEut RPJl)

Turbine Specific

SeeedrIbullntbull

( 6)

o-9middot1 0-9-2 0-9-3 o-lt)-4 09-$ 0bull9-6 0-9-7 0-9-8 0-9-9 0-9-10 o-9-11 0-9-12

aao 994

111$ 1197 1206 1180 11)21081 982 784 5-49 2)9

0middot45oss o6$ 070 07$ 0-77 (l77 or~ o s06o 8 096

123~ 1402 1$80 1698 17bulllS 168$ 16bull18 ~middot5430 1151 a~J4 9

24middotgt24middot3248 25~25 260 260 259 267 266 26middot1 2S2

sos 577 63-7 671 676 650 621 60036J4

327 178

$) 610AlO 3$

92S 980

102$ 1070 1157middot 1230 1300 137Smiddot

44middot4 soo 523 ssomiddot 540so6 46-5 432 368 274 18~8

J46 176 21-1 255 2802s_A 28 289 288 265 231 168

1-4-1 1-4middot2 1-4-3 1-4-4 1-4-5 1-4-6 1-4-7 1-J-8 1-4~9 1-4-10 1-4-11 1-4-12

10bull48 1231 13-S6 1397 1)821375 1))8 1303 1127 953 683) 51

048 067 o7A07 0 bull79 oa1 oss o bullao osa 0lt)0 096 099

J468 1740 1921 1978 1958 19$1 1911 lSSi162 1)98 1045

603

266 264 262 262 261 2512$7 2$6 24middot7 24-3 233 217

551 660 13middot3155 75-6 7~-97 middot4 72$ 67 51middotJ 44middot9 21middot1

475 605 A4220

875middot 910 970_

1000 1090bull 1166 1243 1330

5816

44middot444middot5 430 427 412 392 329 273 188 l0-7

117 101 204 22$ 2)7245 2562sa 257251 222 179

a-C))

Appendix Ct CALCULATED -DATA ( Ocntinued)

1-6middot1 1023 o$2 14-41 26S 505 41~6 26~

54middot5 13middot3l-6-2 1201 067 1boo 625 47-9 17shy~middot41-6bull3 1296 oA9 1 middot43 26 9 700 so5 20bull 4 l-6-4 l3j5 o 0 19~09 268 71bull3 A5o 514 222 1-6-5 1) 5 o81 19(gt4 271 725 51-5 238 l-66 1398 081 198) 27-0 736 8 S13 252~-middot l-6j 1405 083 199i 211 733 885 $middot06 2$9 l-6 13middot9~ 103 2amp 0 279 71 8 985~ 467 ~-69 1228 1 bull 02 17-SS 270 661 109$ 407 ~3~ l-6bull10 1025 100 lSll 26i 573 1175middot 27~S32middot~l-ampu 153 1-00 llft3 26 444 1270 22 24bull8 1bull6-12 294 100 52a 231 22 3 1360 95 172

1-9bull1 904 048 1275 2J4Z $28 S4$ 459 1$2 1-92 98$ oss 13-92 24middot4 57-0 6JO 49bull1 176 1-9middot3 1110 066 1$76 24middot9 63middot4 I2o 536 21-7 l--9-4 1187 072 1685 251 66$ 5 $$ bull 0 261 1middot9-5 llltJ7 1710 25middot4 67-3 93$ 536 28~20-671middot9-6 1186 o 8 1708 25-7 67) 980 $15 2691-9- 1161 oBo 1660 2$middot3 6$6 990 508 29-1 l~- ll-32 oB) 16sect0 2$8 632 1030 471 291 1-9bull9 109$ oa5 2$7 614 1075 29S~middot 0 4imiddot41-9-10 9~91 oas 262 S$1 1150~ 3 o 292 1-9-11 o9o u57 12JiO 21gt 26-77middot74

-45 26sect ~middot91-912 $69 091 sas 25 middot3 1)0$ 196 2J-8 1-9-1) 220 098 426 2)9 178 1390middot 84 16 6

0 0

Appendx C CALCULATED DATA (Continued)

Turbine Run Generator Generator lurbine Turbine Eft1e1eney Turbine lurbine Spee1f1c

Number Output Losses Outit Input Speed Output SPed middot k_-V KW R _ H_bull_P Percent r Thm HP rpm_ (9) tlo) 11) middot (12 _) (lJI ( ) (1$ (14)

2-9-1 9--46 055 1)62 258 528 580 164 2-9-2 1024 056 248 58 4 665 4 9 191iimiddot48 4~middot0 2-9-3 1132 067 05 2$0 641 795 52q 237 2-9-4 1148 065 1027 2$1 -~8 845 525 252 2-9-5 11 77 oso 16-83 253 6 910~ 522 270 2-9 6 1122 071 1600 251 622 960 47-5 2722-9-A 1092 015 1562 257 608 1010 445 2z12bull9- 1052 079 1514 261 580 1060 41middot7 2 2 2middot9-9 986 o82 ]429 26) 542 1105 372 277 2-9-10 915 086 1340 268 500 1160 334 27-6 2-9-11 638 087 972 254 )81 1270~ 229 250 2-9-12 )28 090 828 259 )19 1295 179 226 2-9-13 192 094 383 2$ 6 150 1370 7 3 152

-3 0

Page 5: The Effect of A Variable Draft Tube Flow Area on the

bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull

bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull

bull bull bull bull

bull bull bull bull bull bull bull bull bull bull

bull bull bull bull bull bull bull bull bull bull bull bull bull

TABLE Qf CONTENTS

Chapter

I INTRODUCTION bull

A Purpose and Scope of Investigation bull bull bull bull l B Reaction Turbinea bull bull bull bull bull bull bull bull bull bull bull bull 2 C Draft Tubes bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull 5

II DISCUSSION OF TURBI NE LOSSES bull bull bull bull bull bull bull bull 1

A General bull a Shock Loae ~ c Exit Loss 12

III PROPOSAL OF ALTERNATE METHOD OF CONTROL bull bull bull bullbull 14 A Type and Location of Control bull bull bull bull bull bull bull B Estimated Eftect on Actual Turbine bull bull bull bull ~ c Requirements tor Teet Verification bull bull bull bull 19

IV APPARATUS AND METHODS OP TESl bull bull bull bull bull bull bull bull bull 23

A Equipment bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull 23 B InatlWilentation and Measuring Devicbullbull bull bull 26 c Operational Pz-ocedure bull bull bull bull bull bull bull bull bull bull 26 D Schedule ot Rune bull bull bull bull bull bull bull bull bull bull bull bull bull JS

v DATA bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull 37

A Original Data bull bull bull bull bull bull bull bull bull bull B Calculated Data bull bull bull bull bull bull bull bull bull bull bull bull bull ~A

VI TEST RESULTS bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull 44 A Presentation of Results bull bull bull bull bull bull bull bull bull 44B Discussion of aeaults $1

VII CONCLUSIONS bull middot 56bull bull bull bull bull bull bull bull bull bull bull BIBLIOGRAPY bull bull bull bull bull bull bull bull bull bull bull 51 APPENDICES bull bull bull bull bull bull bull bull bull bull bull 60

A lfotation bull bull bull bull 61 B Original Data bull bull bull bull bull bull bull bull bull bull bull bull bull bull 6)c Calculated Data bull bull bull bull bull bull bull bull bull bull bull 67

bull bull bull bull bull bull bull bull bull bull bull

bull bull

bull bull

LIS~ OP_ __ ILLUSTRAfiOBS-middot

Fiere Page

1 13 $ Inch Reaction turbine bull bull bull bull bull bull bull bull bull bull 4

s bull bull bull bull bull bull bull bull bull bull bull bull

Plow Area bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull 4S

2 Turbine Runner Vector D1agrama and Shook Loaa Diaptama bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull 10

) Turbine PertoPmance CurYea bull bull bull bull bull bull bull bull bull bull 20

4 General View ot Teat Equipment bull bull bull bull bull bull bull 21

6 View ot Teat ut-bine bull bull bullmiddot bull bull bull bull bull bull bull bull bull 7 Teat Generator and Platform bull bull bull bull bull bull bull bull bull 27

8 Iutrument Board and Field Rheostat bull bull bull bull bull 27

9 Vlev ot Water lUteoatat bull bull bull bull bull bull bull bull bull bull 29

10 View or Water Rheostat bull 29

11 Vater Plow Diagram and Electrical Laout bull bull bull 30

12 Sketoh ot Draft ltlbe and Teat Inaerta bullbull bull bull 33

13 View ot Dratt Ube Inaer bull bull bull bull bull bull bull bull bull bull 34

14 Vlev ot Dr~t lube Iuert bull bull bull bull bull bull bull bull bull 34 lS Curves ot Generator Voltage Drop and Copper

Lose bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull 40 16 euvtee of Oenerator Stray Power Lobullbull bull bull bull 41 17 Turbine Charae ter1at1ca with lOOC Dl-att lUbe

18 Turbine Characteristicbull With 7SC Draft tube Flow Area bull bull bull bull bull bull bull bull bull bull bullbull bull bullbull 46

19 Comparleon Between 7S~ and 100 Pratt Tubbull Flow Areas ot Power and Etf1c1ency at OVer Gate Condition bull bull bullbullbull bull bullbullbullbullbullbull 47

bull bull

~ Q ILLt1SlATlOIS (Continued)

F1pe

20 Comparison Between 15 and 100~ Draft Tube Flow Areas of PoweP and Ett1c1enoy at Halt Gate Condition bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull 46

21 Oompu1aon Betwen S~ and 100~ Draft Tube Flow ANaa ot Po-r and Efflctency ab Ovbullbull Gate Condftimiddoton bull - bull bull bull bull - bull bull middot bull bull bull 49 Compar1aon ot Spec1tic Speeda tor 75~ middotand 10~ Draft Tube Flow Areae bull bull bull bull bull bull bull bull so

I

bull

filE EPPEOI OF A VARIABLE DRAFT TUBE FLOW AREA

ON THE PERFORMANltJE OF A REAOTIO TURBINE

Chapter l

IITRODUClIOH

A hrpose and Scope of Invst1pt1on

Present day control of reaction turbines is accombull

pl1ahed by the use of wicket gates immediately- preceding

the turbine runner These gates otter an interrelated conbull

- trol to the quantity and direction ot the water entering

t-he runner ie a change in the amount ot flow will rebull

middot ult in a change in direction This combined control leada

to loesee at all but the rated or design condition ot the

turbine (2$ Pbull )71)

This investigation dealt with an att mpt to better

turbine performance at all points of operation b y the

eatabliahment of separate controls over the rate of flow

and the d1J~ect1on ot the entering watebullbull

The only physical modification of the test tlutbine

was the insertion of flow restricting device in the dratt

tube

Ot primary interest were the trends in the change of

2

turbine performance with the amount ot draft tube tlow

area To this end complete turbine charaeteristiea were

not obtained tor 0ach device inserted in the draft tube

It was considered sutt1e1ent to obtain data tor the tull

speed range tor two representative gat openings one

greater and one less than the rated gate openingbull

Before proceeding with th report ot this 1nvest1gabull

t1on it 1a desirable to supply sa b ckground m terial

on reaction tw-blnes and their dratt tubes

B Raot1on 1rbinea

A hydraulic turbine is a device for converting the

energy in water to eohanical energy (6 Pbull 93lbull96S) furbull

b1nes may be loosely grouped into one of three elasse

impulsmiddote 1 reaot1on or propeller

An impulse turbine normally operates under a high head

and with a relatively sma~l amount ot watel in the converbull

sion or kinetic nergy to mechanical energy The propeller

turbine utilizes pressure energy to develop mechanical

energy while under a low head and p ss1ng a large amount of

waver

The reaction turbine lies somewhere between these two

extremes It changes both pressure and kinetic energy

while oper ting under a medium head with a moderate ount

opound water An example or a reaction turbine is pietur d in

Figure 1

lhe terms of high low small and so tomiddotrth are only

relative in sense A turbinebulls class1f1 eat1on is depenfent

upon its hoad rate of diacharge and speed of rot tion A

useful index tor turbine comparison (5 Pbull 825) is termed

specific speed and this ia a function of the rated ipeed

power output and head or the turbine The common range in

values ot speoitic speed ($ Pbull 826 ) tor each type ot tlirshy

bine is

Impulse J to SS tor one nozzle)Reaction bull 22 to 80 Propeller - 85 to 170

The development of t he reaction turbine began in the

early part or the nineteenth century (26 Pbull 1217bull1)6)

The trst efficient inward tlow turbine was de igned by

James B Francis an American in 1649bull For many years

turbine design was a matter of cutbullandbulltry in America an4

pure mathematical analysis 1n Europe It was not until the

two schools began exchanging ideas in the l$tter halt ot

the n1neteenth century that pronounced advancement was made

in the field

ObTioual7 the primary pux-pose ot any turbine inatallabull

t1on is t he production of power Added to this is the

restriction that the production or power must necessarily

be a controlled process An example of this is where the

turbine is direct-connected to an electric generator which

4

Figure 1 - 135 Inch Reaction Turbine

5

must operate at a constant speed or rotation even though _

the power demand ohangos In thiamp case the turbine nuet

be eap~able or producing a range of power output yet menshy

ta1n e eonetant speed

Speed regulation of the turbine iv accomplished by

means ot a governor (23 Pbull 24bull3-7) bull The contr-ol or regulashy

tion 1s indirect that i s the governor actually exereiaabull

control over the water in order to JJaintain e given speed

Co-ntrol over- the turbine end bence its speed and

power is the function ot a ring of movable wicket gates

located just upsttteam of the turbine runner These w1eket

gates 1n the process of opening and closing upon eeeh

0~1ar in a rotational manner actually control the amount

velocity and direction of tne water passing throu~~ them

C Draft Tubes

It has been found that the effeetive head on a reae

1l1on middotturbine is increased with the addi timiddoton of a draft tube

(3 Pbull 256bull264) Tne draft tube does thin by~

(1) Making a greater presaure d~op across the turbine

possible by the creation of a negative pressure at the

discharge or the runner and

2) DeoreaGing the k1net1e energy lost by increasing

the eross sectional area at exit

he draft tube permits the turbine runner to be

6

located above the tail race water surface without the

sacrifice of head However cavitation will cause pitting

of the turbine if the difference in elevation is too great

A common maximum elevation difference is 19 feet although

this figure is quite subject to modification between difshy

ferent installations (3 p middot 264-266)

There are many different types or draft tubes in use

today the choice or type being largely a matter or

economics (2$ p 368-370) A very common type particushy

larly among the smaller units is vertical with flaring

sides However the angle of flare is limited by the possishy

bility of separation of the flow from the sides In order

to achieve a certain discharge area the length of the tube

may be such as to require a great deal of excavation In

oases or this sort the cost of this excavation must be

balanced against a more elaborate design that does not

require as much excavation Other draft tubes in use

include the elbow hydracone and spreader types

Despite the differences found in construction and

design the draft tube must accomplish the desired objecshy

tives while offering a good hydraulic geometry to the flow

passing through it An inefficient draft tube defeats its

own purpose

Ohapter II

DISCUSSION ~ TURBINE LOSSES

A General

lhe head that 1a actually utilized by the turbine 1a

less than the effective bead as defined by equation ($) by

the amount that 1a lost due to mechanical and hydraulic

reasons

Mechanical loaaea are a function or the turbine 8p$ed

fhis ia not a lineaz- function but varies eomewhere between

N and N2 (3- Pbull 224)

Hydraulic losses encounteled in turbines ma- be subshy

divided aa to the location or occurrence (3 p 225-227) aa

fOllOW$S

(1) Penstock and scroll case

(2) Wicket gates

(3) Between wicket gates and turbine runner

(4) Runner passages

(5) Runner exit into draft tube

(6) Draft tube and

(7) At exit from the draft tube

The flow in the penstock scroll case wicket gates

runner passages and draft tube may be envisioned as

examples of flew in conventional pipes elbows and convergbull

1ng passages If this comparison may be made it could be

assumed that the losses encountered in these locations

would be proportional to vn ~ value ot N is normally2g

aesU111ed to be 2

he losses encountered between the wicket gates an4

the turbine runner and exit lossos are special cases which

will be discussed separately

B Shock toes_

The flow betwe n the wicket gat outlet and the runner

blade entrance is or particular 1nt rest because no direct

comparison vith common flow situations is obvious

Conaider the vector diagram (7 Pbull 7576) in Figure 2

The veetoo v1 is the absolute entering velocity of the

water and is fixed in magnitude and direction by the setbull

ting or the wicket gates The vector l11 1e the peripheztal

velocity of the runnel which tol any given turbine 1e

dependent only upon the turbine rotational speed The

combination of these two vectors ylelda the third vector

v1 which is the relative entering velocity ot the water

nere is only one setting ot the wicket gates for a

given turbine a peed that will produce an angle B1 which

coincides with the blade angle B1bull At other gate settings

the vector v1 will rotate and change in magnitude in such a

9

t ehion that B1 will beoome either greater or 1 sa than B1bull Th1 give rise to tbe phenomenon term d shock loasft

If B1 1a greater than B1 the relative ent ring veloebull

ityt v1 will have a compon~nt opposing the forward motion

of the runner The shock loss could be typified bullbull that

occasioned by direct impact or the water 0n the blade- If

E1 is lese than a] the vector l will overshoot the blade

and the flow will tend to eddy around the forward portion

or the blade tip

The shock loss can then be either due to impact or

eddying flow Since the area norm 1 to the radius at outlampt

of the w1eket gftee is essentially equ 1 to the area normnl

to the rad1u~ at the inlet to the turbine runner the combull

ponents ot vl and vl perpendicular to ul will b approxishy

mately equal This leads to the conclusion that xxbull ~epresenting the shock vector 1 parallel to Ulbull

For either the impact or eddy case the trigonometric

law of $1nee leads tot

XX

bull ul - sin (Bi-Al) vl eln Bi

It it 1a assumed that the energy lost in the shock 1a

the Telocity head ot the shock component XX then

10

VELOCITY VECTOR DIAGIWI

TYPES OF SHOCK LOSS

xbull X

IMPACT BDDJ

XX 1a Teloc1t7 caponent ot shock

Figure 2 - ~bine Runner Vector Diagram$ and Shock Loss Diagrams

11

2 shock loss (XX gt2g

C =sin (BimiddotAl)Let (1)sin Bi

(UlmiddotCV1)2Then shock loabull (2)- 2g

For a given gate opening C ia a constant ranging

from about 14 to 10 For a well designed wheel it is to middot

be expected that C would be approximately equal to U1V1

at rated conditions ie at point of maximum efficiency

This point will occur in the neighborhood of 3~ to 78

gate opening for moat turbines For overgate conditions

the angle A1 becomes larger so the value of C would

decrease For gate openings below rated conditions t he

angle A1 decreases and C would decrease One could expect

a fairly uniform decrease in t he value of C as the gate is

closed from t he overgate position

The velocity v1 is approximately constant for any

turbine speed since the area and rate of flow both decrease

fairly uniformly However for a given gate opening the

velocity V1 will decrease with increased turbine speed

From the foregoing comments and equation (2) the

following trends can be established

(1) For constant turbine speed the shook loss curve

will be close to parabolic in shape concave upward and

have its maximum near t he point of complete gate closure

--

12

and its minimum near the rated gate position

(2) For conatant gate opening the shook loss curve

will approximate a symmetrical parabola with its vertex

the point of minimum loas located at the rated condition

of operation (7 Pbull 79)

c Exit Loas

It can be seen from Figure 2 that the exit loss from

the turbine would be v222g if no draft tube were present

The addition of a draft tube permits the gradual reduction

of velocity by an increase in cross sectional area between

the exit of the runner and the exit from the draft tube

The exit loss and the frictional loss encountered in

the draft tube may be placed together in the expression

m va2 (3)Exit Loss ~---2g

For the ideal case of no friction in the draft tube

m is equal to the square of the ratio of the area at exit

from the runner to the area at exit from the draft tube

In an actual turbine installation however friction

will change the value of m (7 p 84-85) to somewhere

between that for the ideal case and a maximum ot 10

In the interest of maintaining a minimum exit loss

the turbine should be designed and operated so the velocity

V2 will be minimum This will occur when the discharge

13

vector is at right angles to the tangent to the runnerbull

ie the angle A2 1e ninety degree bull It ia to be expected

that this condition will be tultilled near the design con~

d1t1ons ot the ~bine

Current design praetiee 1 to have a small component

ot v2 in th$ direction of turbine rotation at rated condibull

tion$ ltS p 938)

For a constant turbine speed the d1seharg or exit

loss is ess nti lly a constant

For a constant gate opening the exit lo s curve is

aptrroximately a symmetrical pa~abola with ita vert x the

point or minimum loss located at a slightly lowe~ speed

th n the turbine rated speed (7 Pbull 79)

Chapter III

PROPOSAL OP ALlERMAlE MFTBO 0 CO TROL-A lz ~ Location 2 Control

Thua tar only practice and theoretical aspects appemiddotrbull

taining to present day turbinea have been d1acuaaed It

haa been presented that control over the ~bine ia ezerbull

oiaed b y manipulation of the wicket gatea located 11101led1bull

ately preceding the runner These gate - upon rotation

modify both the magn1tu4e and the direction ot the entering

velocit7 Moreover it has be n shown that a simultaneous

change in these two variables leads to inefficient operabull

tion by the introduction of shock loss he farther the

point of operation a from the rated conditione the more

aerioua ia the ahock loss encountered

Any attempt to better turbine pertorance at other

than rated conditione and tbne flatten the top ot the

etticieney hill8 must concentrate upon the lessening ot

the ahock loaa It 1a a aumed that 1 provement in the

scroll case gates and runners would lequ1re sueh pertecbull

tion 1n machine work and metal$ as to be prohibitively

expensive

It ie surmised that any move to elblinate eYen parbull

tially the shock loss would require separate control ovel

l$

the flow and gate exit angle Since it is improbable that

d1~ect1on could be controlled at any location other than

where the gatea are situated in current turbines it will

be assumed that guide vanes will be necessary regardlesa or the method used to control the rate of flow

The primary purpose ot th se guide vanes 1s that or control over the direction ot the incoming water They

should be free to rotate in much the same manner as ordibull

nary wicket gates in order to exercise control over th

turbine speed

If the rate ot tlov is to be controlled elsewhere it

must be modified either in the penstock or the draft tube

Devices that could be used are standard valves gates

variable orifices variable venturi sections and associated

flow regulating schemes

Alauming it were decided to locate such a device upbull

stream of the turbine it would be necessary to allow disbull

tance tor the flow picture to become reestablished prior to

entry to the turbine A contused flow making transit of

the turbine passages would only contribute additional loesbull

ea Such a distance allowance would be perbapa 20 to So

diameters (2$ Pbull 119-123) In large penstocka th1a would

repreaent a considerable distance Which from the viewbull

points ot convenience and control would be undesirable

Attempts to ascertain the effect or additional tlov

16

reduc ion at the wicket gatctsmiddot wae ade 1n the lfadraulioe middot

Laboratory of Oregon St middot te College in 1933 (20) Three

d1tterent thode ot reducins the tlow were t~ied

(l) Locking in the cloeed position pairs or wicket

gatea located opposite to eaeh o~er on the -periphery ot

the wheel

(2) Locking adjacent gates in an open position by

inserting blocks of wood between them and

()) Suocess1vely looking adjacent gates in the closed

position

The results indicated a arked reduction in both power

and efficiency when compared to the curves tor normal gate

operation However it was demonstrated that it was poae1bull

ble to ahitt the power and tfieiency curve ill relation to

turbine apeed lbis important feature will be diacussed

later

ihe main conclusion of the investigation was that conbull

trol by the conyent1onal wick t gates was auper1or to other

methode egtt control exercised at the gates the aelvebullbull

It would app$ar that the bebullt location tor flow conshy

trol would be in the draft tube since none of the objecbull

tiona prev1ously mentioned wou~d eziat there

As bas been stated previously the sole object or the

17

18

turbine is to produce power as etfic1ently as possible

The equation tor the power output of a turbine () Pbull 227)

PaWHe HP (4)55o bull bull Assuming the head 1a constant and a g te located in

the draft tube decreases bhe rate ot flow the power eu

only be increased if the etticiency increases

The ettective head Gn the turbine 1s conventionally

d r1ned as the difference between the auma ot the elevashy

tion head pressure head and velocity head at the entrance

to the turbine casing and the tailrace ($ Pbull 872)

lt ie recognized that the theoretical treatment ot

shock loss as given is highly approximate and serves only

to dictate certain trenda For example the area at xit

rom the wicket g tea CfUl be measuPed with some exactness

but there exists no guarantee that the wateP particles will

complet-ely fill the apace oz- will exit at the establiahed

g te angle The same can be said of the exit trom the

runner blades AssUIlptiona were implied which would indishy

cate that all water particles passing a given croea section

ampH traveling at the same velocity in the same direction

the e alone are autt1c1ent to show 11m1tationa in a theoretbull

1eal approach to the problem

Assume a turbine with ordinary wicket gates tor oonbull

trol compared gainst the same turbine with a gate in the

18

draft tttbe tor supplampment1ng control or the rate ot rlow

Let it also be assumed that the two turbines are opershy

ating at the same point It 1s desirable to predict relabull

tive performance of the two turbines 1 this point of

operation is such that edd7 s hook loss ot reasonable proshy

portions is present in the fir t turbine

~ tull erteot of the shock loss will be exper1 need

by- the fir t turbine

lhe second turbine will derive certain advantages 11

the gate in the draft tube is adjusted to reduce the tlov

1n the proper amount Since they vary a the square ot

the veloo1t7bull the lossabull in the aeroll case wiomiddotket gate

and runner passages will decx-ease aetet-r1ng to Figure 2 1

it can be seen that a decreased velocity v1 w-ill reduce the

eddy shock losa

The ent loss in the dJtaft tube of the second turbine

will be the sum ot the tr1ct1onal loss and the velocity

head at ex1t The velocity head dissipated will be greater

due to the closing action or the gate but the reduoed

t~ictional loss which ia a tunction ot the rate of tlow1

will partially balance this

It 1a entirely possible that the net reduction in

losses in the second turbine will lead to a greater ettibull

oiency and more power output than 4eYeloped by the first

turbine

19

In Figure 3 the plot ot power output against turbine

speed for Curv A~ represents the typical family of curvea

tor a reaction turbine Th b st sp ed is the locus ot

points connecting maximum eft1oiency at each gate opening

The operating speed is the coZUJtant turbine apeed which

passes through the point ot maximum efC1ciencr of the turbull

bine The plot of turbine efficiency against power output

for Curve A is also ahown

It the turbine with flow regulation in the dratt tube

oan demonstrate superior power and efficiency at part loads

the effect would be the same as a shifting or the power

curves toward the condition shown fop Curve B 11 Thisbull

illustrates th ultimate case of the uperpoait1on of best

and operating speeds It will be noted that the pet-form~

of the turbine ot Ourve Bu 1a better than that of CUrve

A at part loads because of ita ability to sustain a relabull

tively high etticienoy ovel a Wider range of power output

o Reguireaegts tort Test Velitication

It is desired to deterra1ne the effect on the turbine

performance b) the addition of a gate in the dratt tube

Th step in the teit will bet

(1 To determine the power output and efficiency ot

the turbine tor wicket gate settings above and below rated

conditione for a wide range ot speed

20

CURVEAbull

TURBINE SPSBD TURBID SPEKD

POIBR OOTPOl

Figure 3 - Turbine Performance Curves

21

22

(2 peat (l) with the gate installed in the drat

tube

(3) middot Converting middot all data to a constant head compare the

powere and effioiencies at the same wicket gate setting and

turbin speed tor the two cbullses

If the ddition or the gate indicates an improvement

in power output and efficiency and the powe~ curve shifts

to the right along the turbine apeed scale the advantage

ot draft tube con~ol of the flow will hav been demonshy

strated

Chapter IV

A E9J11pment

ih turbine used in this test is lJ 5 1nch Pelton

reaction turbine with a rated output ot 30 horsepower under

a head of 56 feet at a speed ot 720 reYolutiona per minute

Views of this turbine are hovn in Figures S and 6 The

turbine is installed on a concrete pad located over an open

channel in the Hydraulics Laboratory at Oregon State Colshy

lege The date of manufacture of this turbine was 1915

The water was delivered to the turbine from a sump

reservoir by two pumps operating 1n parallel Each pump 1a

an 8 inch Pelton double suction centrifugal pump witb a

rating of l$00 gallons per minute at a head ot 75 teet with

a speed ot 1175 revolutions per minute Tbe inlet tlange

ot tne turbine is $pprox1mately 18 feet above the center

line of the pump

A direct current generator was coupled to the turbine

to receive tne power d veloped as shown in Figures 4 and 7 The generator is a Spr gue Electrodynamometer rated at SS horsepower with a speed range of 7$0 to l$00 revolut1one

per minute The classification is type LO 26A 2)0 volta

Figure 5 - View of Test Turbine

Figure 6 ~ View of Test Turbine

and 149 amperes lbe generator ti ld was aepar tely

excited using direct current from a motor g n r tor ampt

(l$ p 4~8)

The power output of the generator waa dissipated in

the water rheostat (3 p 488-489) shown in Figures 9 and

10 The galvanized tank contain d water ot variable d pth

on an electrode ot cast iron m aauring 1bull x 1 x 1

In the initial installation of the turbine it was

intended that the power output should be measured with a

Prony brak bull For th purpoa68 or this teat it was decided

that the brake was too instable and the generator was

substituted The platform for raising the generator the

nee asary two teet for alignment was built out of available

material In this case heavy laminated wood blocks reiashy

torced with other timbers were used and bolted through the

concrete deck (11 Pbull 36-$7)

Due to the light concrete deck the lack ot mas in

the platform and the slight misalignment in the flexible

coupling ao e vibration waa encountered It seemed to

ncr aae linearly to a maximum at the speed of bout 750

revolutions per minute Above this speed no vibPation was

noticeable The vibration waa not se~ere and does not

appear to have materially affected the test results

26

B Intrumentat1on ~ eaeur1ng Devices

The pressure head at inlet to the turbine vaa meaave4

bymeane ot two )6 inch waterbullmeroury manometerbull connected

in series as shown in Figure 8

The terminal voltage ot the generator vas meaeured by

a laboratory voltDleter with a range to )00 yolta and callbull

brated to within 15 Yolta

The armature current bull and hence the line current was

measured by a laboratory ammeter with a range to 150 amperea

and callbrated to w1 thin o 7S amperes

Tae rate ot tlow was established by weight and time

meaeurementa The weighing ank has a capacity ot 121 000

poundsJ the weight belng indicated by Toledo direct reading

scales Timing was done with a hand atop watch with clivibull

aion ot 02 second

he ~ater level in the tailrace was dete~1ned by a

hook gauge lhie was read to the nearest 001 toot

The turbine and generator speeds were eaaured by a

hand tachometer The technique of almost cont1nuoua readbull

ings of the speed gave an error ot no more than 5 revolubull

tiona per minute

c Operational Procedure

Atter the water level in the aump was checked to

insure an adequate auppl7 the puapa were primed and

27

Figure 7 - Test Generator and Plattorm

Figure middot8- Instrument Board and Field Rheostat

28

started After venting they were valved for operation 1n

parallel

The motor generator set was started to supply the

field current and the circuit breaker was closed Water

wa added to the water rheostat to the level shown in

Figure 10 ~ field current wae minimized by cutting in

all the f ield resistance in the field rheostat of Figure 8

The l2 inch gate valve shown in Figures 5 and 6 waa

slowly opened and the turbine and generator brought up to

speed The 12 inch gat valve and turbine were vented and

the pumps were checked to insure neither had lost ita prime

lhe water rheostat offers very steady load 1f the

water level is essentially constant and the water temperabull

ture 1a fixed () p 488~89) In order to maintain this

constant temperature it was decided not to circulate the

water in the rheostat but rather to allow the water to

boil thua achieving the desired result A standing wave

was set up on the face ot the electrode by the boiling

action but a atable load was eatablished except at very

low water leYels where th11 agitation led to fluctuationa

in the line current

After putting the turbine and generator on the line

maximum power was dissipated in the rheostat by redueing

the turbine speed to between oSO and Soo revolutions per

minute Salt vas added to the rheoetat wat r to increasemiddot

29

Figure 9 - View of Water Rheostat

Figure 10 - View of Water Rheostat

Separate Field ExcitationFrom Motor-Generator set Compound Water-Mercury

---shy

re Manometer

I Q)

~ 0

~

Book Gauge

Open Channel

I

Slap Reservoir

Figure 11 - Wat~r Flow Diagram and Electrical Layout

31

waiting pe~iod ot perhaps an h~ followed

while the boiling point or the water wbulls reacbe4 During

this ti+ne the manometer was vented end eheoked electrical

measur1ng 1nstlUments were connected end the hook gauge was

adjusted tor elevation

It required about two- houtte tor the generator to reach

its normal operating tempe-ratu~e_ After the water in the

rheostat and generator had reached their operating temperabull

turea it was possible to begin the taking of data

The only vaPiable which was controlled wee the turbineshy

generator speed However the upper l1ut1t of safe line

current was slightly over 100 ampJilPampPes and the eireuit

breaker would open when the current reached lOS ~ere bull

Control was exercised by means ot regulating the water

level and salt 1n the water rheo tat and the res1stsnoe of

the tield rheost t~

The etfeet ot each type ot regulation on the three

variables is shown below

Volta Aaperebull Speed

Inc Dec Inc Dee~ Inc Dec

Wa~e1 Level Inc Dec~ X

X X X X

X

Salt Concentration

Inc Dec X

X X X X

X

field Resistance

Inc Dec

X X

X X

X X

32

Jlot all methods gave the ame amount ot change in a

given variable and a period of experiment and trial led to

the following scheme starting the rune with the lowest

turbine speed the water level was high with a high amount

ot salt and the field resistance was cut completely out

Aa it became necessary to increase the speed tor each

aucceasive run either cutting in t he field resistance

decreasing the salt concentration or lowering the Vater

level would produce the desired result However decreasbull

1ng the salt concentration had to be done Without a net

gain in water which led to a tluahing procedure that was

not particularly good because cold water was introduced

which required time to heat to the boiling point Cutting

1n additional field resistance was a good method but th1a

increased the amperage possibly to the point of opening

the circuit breaker Lowering the water level was aatiashy

factol1 until the level got too low causing the current

fluctuation previously mentioned Actually it turned out

that a combination of lowering the water level and cutting

field resistance in would carry the speed from ita minimum

to 1ts maximum value it the proper choice were made each

time the speed waa to be changed At the conclusion of

each aet of runs at a high speed the water level would be

low and the field resistance high

33

TURBINE

PAD AND DECK

TAILRACE

WATER SURFACamp

CONCRETE

DRAFT TU1B INSERTS

7 5( DRAFr TUBE

FLltJI ARIA

5~ DRAFT TUBE

FLOI ARSA

Figure 12 - Sketch of Draft Tube and Test Inserts

34

Figure 13 - View of Draft Tube Insert

Figure 14 - View of Draft Tube Insert

D c __ ~s_middot hedu_le of

A number was assigned to each run The fi~st number

applies to the draft tube tlow areas

1 bull 100~ flow area or 0~ oonatriction

2 - 7S tlow area or 2$ conatr1ct1on

3 SoC flow area or so~ constriction

The second number refers to the wicket gate openings

9 over gate opening

6 bull intermediate gate opening

4 bull one h lt gate opening

The third number 14entif1ea the location of the particular

1Wl in a set ot rona made at a given dratt tube tlow area

and wicket gate opening

fnua run number 1bull4bull10 would identity this as the

tenth run ot a set made at halt gate with 75 ot the draft

tube t1ow area

Rune w re made tor a g1yen dratt tube condition

Firat tor tull 41-aft tube flow area seta ot rune were

made for the overgate halt gate and intermediate gate

conditione An insert was placed in t he draft tube and

rune based on the same gate conditions were made tor the

7S~ draft tube flow area case The insert was then changed

to allow only $~ draft tube flow area

The inserts are sketched 1n Figure 12 and photographed

ln Flgurea 13 and 14 They oonaisted of circula~ segments

36

or l2 ineh plywood mount 4 on wooden legs 10 inches high

The 1nse7te were placed in position and secured by th use

ot a-clamps on the legs and the outside ot the bottom of

the draft tube The obvious disadvantage to this method

waa the neoeasity tor draining the water from the tailrace

tor a change ot 1naert The advantage vas of course the

simplicity ot design and construction

Chapter V

DATA-A Original Data

The normal data-taking crew consisted or two men

Assuming adjustments having been made to secure a certain

turbine speed (aee section on Operational Procedure) one

man would take semi-continuous speed readings with the hand

tachometer until a state or rotational equilibrium was

reached This could be only a period or two minutes up to

ten or tifteen minutes As soon as steady speed was

assured the data taking would begin The second man went

to the weighing tank Where a minimum ot three weighingamp

were made The requirement was to get three consecutive

readings such that the ditterence between tbe smallest and

largest time did not exceed 04 seconds The time to

collect a given weight ot water was then assumed to be the

arithmetic average of the three times He then went to the

hook gauge determined the hook elevation and then

recorded the data on the data sheets The first man meanshy

while had taken readings of the line voltage line current

and manometers and checked the turbine speed by multiple

readings During the length of the run all values were

38

checked to determine mean values for recording

The minimum length of one run was about five minutes

If one or more measure ants tended to drift during the run

all values wer discarded and a new run began as soon aa

qu111br1um was stabl1shedo

B -0-al_e_u_l_a_t--d Data

The h d on the tu~bine 1 defined by

($)

The maxtmwm velocity V4 was equal to about o8 tampet per

secon4 which makes it a negligible quantity when converted

into velocity head

An engineerbulla level was used to deterine the d1ffePshy

ence 1n elevation between the compound water-mercury manoshy

meter and the hook gauge Using this value the equation

for turbine bead becomes

where z4 is the hook gauge reading

The rate of flow 1 cent

w weight or water collected average time to collect

The inlet velocity v1 vas calculated by dividing the

weight rate or flow by the specific weight of water and the

)9

area ot ~e inlet pipe This was equivalent to dividing

the weight rate of flow by 490 Then the power input to the turbine is equal to

WHpin rri

10 (6)

Also

(P ~ut) Turbine

(P out) + Generator

(P lost) Generator

The power output of the generator is simplJ the

produot ot the terminal voltage and the armature (line)

curPent The power lost in the generator can be subdivided

into copper losses and stray power losses lo evaluate

these cunes based on losses of an identical generator

11leampsured by the Department ot Mechanical Engineering were

used The loss curves are reppoduced in part in Figures

15 and 16

Determination ot generator losses proceeds as tollowau

(1) From Figure 15 detem1ne the vo1tage drop in the

armature circuit using the temperatures of 1220 F and the

meaaured current

(2) The induced voltage is t~e sum of the terminal

voltage and the voltage drop 1n the armature circuit

() Entering the induced voltage and the turbine speed

into Figure 16 the stray power loss can be determined

(4) The copper lose can be evaluated from Figure 1$

using the measured current and the temperatlll-e of 1220 P

40

25 ~------~--------~--------~------~

U) -U) - 20

f-4 ~

-~ -gt 0

0

VOLTAGE DROP

~ - i -

- bullbullbull bull - -middot-middot -+ ~- + -t--+ ~ - ~ middotbull ~-~ middott- -+----- _ -4 middotmiddot- --~-+-t---r~~ ~--+t-t- - ---t-c-++~-ulf--

0 50 75 100

Figure 15 - Curves of Generator Voltage Drop and Copper Loss

41

1200

1000

800

600

800

0

0

~-

middot--~ 1shy --1 + bull l

100

I -

150 200

IIDOOED VOLTAGB (VOLTS)

Figure 16 - Curves of Generator Stray Power Loss

_ j

-bullshy -L---- shy middot -shy

250

- r

42

(5) The generator los os equal the sum of the eopp r

loss and stray power loss

~e efficiency or the turbine is taken as

etticiency u e =P out (8)Pin

~ample pound Determ1n1gg turbine Power Output

The following data are taken trom that ot Run 1-9-1

Line voltage 1040 volts Line current 870 amperesSpeed 355 revolutions per minute

The induced voltage 1a determined as follows

Line voltage 1040

Voltage drop 90 using Figure 15 with line current of 870 amperes and temperature ot 122 degrees)

Induced Toltage 1130 volta

The power output of the turbine is determined as follows

Generator output 90$0 (line voltage z line current)

Oopper loss 7 (using Figure 15 with line current of 870 amperes and temperatUe or 122 degrees)

Stray power lose 470 (using Figure 16 with speed ot 355 revolutions per miDUte and induced voltage or 1130 volts)

Turbine power output 9527 vatta

or turbine power output 1s 12z2 horsepower

43

The conversion of the calculated data to a constant

head is based on the conventional assumption of constant

efficiency regardless of turbine head For a constant head

ot 81 teet a purely arbitrary figure the tollowing relashy

tionships are ass1lJiled to be true

I ____L (9) (i)l72

(10)

For these two values the specific a peed may be combull

putedt

N t Jt VPt (11)8 243

Chapter VI

~RESULTS

A -Pr_e_ae_n_t_a_t_t_o~n g Reaultbull

Graphical presentation ot the results ot this te1t

are given as follows

Figure 17 -Turbine characteristics with 100~ dratt

tuba 1low area

Figure 18 - Turbine characteristics with 7S dratt

tube tlow area

Figure 19 bull Comparison ot power and etticiency at

over gate conditions between 100 and

75~ draft tube flow area

Figure 20 bull COZQparison of power and ettic1ency at

halt gate conditions between 100~ and

7S~ draft tube flow area

Figure 21 bull Comparison of power and etticiency at

over gate condition between 100~ and

So dratt tube tlow area

Figure 22 - Comparison in variation ot apec1t1c

speed between 100 and 75~ dratt tube

tlow area

50

45

20

-bull - 1--shy40

bull J-~ 30

~ ex

~ 20

~~ ~ -)q

I

~ - _

- -

10~ OF DRAFT TUBE FL(Jif AREA

CONSTANT HEAD OF 8l FEST10

POIER OUTPUT EFFICIENCY SPECIFIC SPEED

0 ~--------------_--------~------~------~ 400 600 800 1000 1200 1400

TURBINE SPEED (RPM)

Figure 17 - Turbine Char~cteristics with 100 Draft Tube Flow Area

50

46

-bulllle

~ 7 ~ OF DRAFt TUBE FLOW AREA

0 -~~-rl C05STAMT BEAD OF 81 mET 1J~

POIER OOTPUT ---+- ---o ~_H EFFICIDCY ~ I shy

bull ql SPECIFIC SPEKD - ~ -

bull ~ J 10 L rmiddotr- r- -

bullz- I

~~ 30 ~~--~----~~-

20 ~ ~ middot-shy

26

~~ 25

~0 ~r-----i (

Tbull -bullshy

400 600 800 1000 1200 1400

TURBINE SPEED (R PK )

Figure 18 -Turbine Characteristics with 75 Draft Tube Flow Area

47

EFFICIENCY 60

1-----shy

-~ 50~--~--~~-~middot middot middot middot r~-~----~~~~---4~-r~-~~gtt

II

POWER~ J ~ bull bull

u I

sH

40~------+-------+---- -~~--~~-~~~~

~----~rl 1 bull

I

I

0~--------------~------_------~--------

~ -OVER GATE CONDITION

COIJSTANT HEAD OF 81 FEET

0 o 10~ DRAFt TUBE

_-- _ 7~ DRAFT TUBamp FLON AREA II

10_~-----+--------r-------r----~~

400 600 800 1000 1200 1400

TURBINE SPEED (RPM)

Figure 19 middot - Comparison between 75 and 100 Draft Tube Flow Areas of Power and Efficiency at Over Gate Conshydition

48

t

bull --4 r ~- ~ middot~

70 1-----------+-~~~~~+middot ~ ~~ middot middot -~~--~~--------~~----~-+1

-~-

Atbull bull

lla-

60

amp0

40

20

10

oampOO

t _ - - ~-+- - -~-

l2 GATB COJIDITIOJJ

COJISTABT HJW) OF 81 JBET

o 0 lOQ( DRAFl TUB8 FLOI AREA

e-- - e 75 DRAFT TUBE FLOW AREA

800 1000

- r-

~

TURBIbull SPBIID (RPII)

Figure 20 - Comparison between 75 and 100 Draft Tube Flow Areas of Power and Efficiency at Half Gate Conshydition

49

60

50

-40

bull 30

IIQbull

20

10

0

400

- t - ~

EFFICIENCY

_J bull - bull bull

~ r r middot t -+ shy L -t -

OVER GAD COliDITIOI

CONSTABT BEAD OF 8l FBB

o o 10~ DRAFt TUBE FLOI ADA middot--- 5~ DRAF TUBE FLQPi AREA

600 800 1000 1200

Figure 21 -Comparison between 50~ and 100~ Draft Tube Flow Areas of Power and Efficiency at Ove~ Gate Conshydition

50

25

20

15

10

0

Figure 22

~- T -4 -t- -l --~-

t-~ I

middot --~- t ~---- _ __ _ + --

----~- --r-- --

~-=J-~-=-~ -==~ _ ~- -- ---f---1 - shy

CONSTANT HEAD OF 81 FEBT

o--o 1~ DRAFT TUBE FLltll AREA

75C DRMT TUBK FLCIJ AREAmiddot--middot-middot 600 800 1000

TURBINE SPEED (RPK)

Comparison of Specific Speeds for 75 and 100 Draft Tube Flow Areas

51

B Discussion 2 Result

Consideration of Figures 17 and 18 indicates the

overall eftioi ncy pattern or hill is significantly or

rounded for the 7$~ flow area than for the 100~ flow area

bia implies a greateP efficiency is possible at speeds

leas than or greater than design speed with an insert in

the draft tube However the muilDum efficiency is lemiddotas

Direct comparison at over gate conditions is made in

Figure 19 ~e same general trend is noted tor both the

etticiency and power curves for the 7$~ flow area case

The eurves show higher values at overspeed than do the

correaponding cWvea for the 100 flow area case It ia

not clear whether the curves have been shifted by the dratt

tube constriction or whether the curves simply bulge past

the normal curves at both overspeed and underspeed condishy

tions The power curves apparently peak near the aeme

point bullalthough maximum power is still obtained with the

normal draft tube area

For the comparison at halt gate operation shown in

Figure 20 a general improvement has apparently been made

by restriction of the draft tube flow area At every speed

the etticienoy and the power is greater for the restricted

tlow case The two ett1o1ency curves and two power curvea

are practically parallel throughout the speed range ot

teat

As the flou aroa i e decreased still farther a s1gn1

ticant change appears Reterr1ng to Figllle 211 tor the $0

flow area curves it a obvious that exit losses have

become excessive at the overgate condition because the

efficiency and power are everywhere leas than tor the case

of normal draf t tube area

Earlier it was pointed out t hat 1t the r esult s 1nd1bull

eated an increase in both power and ef tieiency- t hen it

could be assumed tha t the additional los s i ntroduced with

the draft tube insert is less than the diminished losses

due to leas shock losa and water passage losses For the

places where both the efficiency and power have been

increased we can assume that the insert has improved turshy

bine performance

For the places where the power haa been decreased

nothing can be said as to the elimination of ampbock loss

because the new lose present with the drat tube insert has

overshadowed any gains in eftecti Ve head upatJ-eam of the

insert

Near the peak of the efficiency hill howeve~ it may

be pointed out t hat shock loaa ie a minimum with a normal

draft tube and the insert merely adds an additional loss

with the resultant decrease in maximum efficiency tor the

7$~ flow area case

Perhaps the most s1gn1ticant set of eurves is shown aa

53

Figure 22 In this graph values of specific speed tor the

75 and 100~ flow area cases for both over gate and one

halt gate openings are plotted against turbine speed At

every speed and both gate openings the value ot specific

speed for th 75~ flow area case is greater than that for

the 100 t1ow area ease

Since the head is a constant for both situations this

may be interpreted in either of two ways trom equation

(11)

(1) For the same turbine apeed restriction of the

draft tube t1ow area resulted in greater turbine power

(2) For the same power amputput the turbine with 75~

draft tube flow area operated at a greater speed than did

the one with 100 flow area

Since the required diameter of a turbine varies

inversely with the speed the second interpretation could

be stated such that a smaller turbine could be used to

develop the same power output

Whether viewed trom the aspect of increased power

greater speed or reduced size the performance of the turshy

bine with reduced draft tube flow area is superior to that

with the nolmal flow are in the draft tube

The curve of specmiddotific speed versus turbine speed for

the so draft tube flow area case at over gate cond1t1ona

was not included in Figure 22 This curve lies below that

for the 100~ flow area c se at all speeds

In elaboration ot the second interpretation of Figure

22 attention is directed to the relative magnitudes ot

increased apee1f1c speed tor the two gate openings Assumbull

ing that the increase in specific speed implies a shift ot

the power curve to the right along the turbine speed scale

the power curve would be shifted more tor tbe halt gate

opening than tor the over gate opening

It thia trend could be extrapolated to the other gate

openings the tendency can be seen tor the line ot beat

speed to rotate toward the line of the operating speed as

illustrated in FigtU-e ) The advantage of this has already

been discussed

This particular turbine has a low specific speed tor a

reaction turbine Aa the rated value of apecitic apeed tor

reaction turbines increases the line ot beat speed departs

even more radically from the line of operating bullpeed It a

test similar to this were conducted on a reaction turbine

ot gleater specific speed it is pJobable t hat the rotation

ot the line of beat apeed would become more p~onounced

The scheme used in th1a teat had two obvious dr wbull

backs The first was the decision to leave all the wicket

gamiddottes installed tor all conditions ot the draft tube

These gates predominated in control of the tlow The

inserts added to the draft tube merely acted as auxiliary

55

contrGla

The aecond drawback was the choice or device to place

in the draft tube The reasons foll selection of this type

of device have been previously mentioned It is to be

anticipated that adaptation ot dratt tube flow control

would result 1n a better device for an actual turbine

installation Such apparatus might take the form of a

pneumatic bladder or a h7drau11oally operated variable

venturi section in the draft tube It is conceivable that

the gate as used in this test might be adapted also

Chapter VII

OONCLtJSIOfS

From the results of this test the following eonolubull

e1ona aa to the effect ot a variable draft tube flow area

on the performance or a r action turbine may be drawn

(1) The effect ot a variable draft tube tlow area 1a

generally favorable upon the operat1Gn ot a reaction turbull

bine because or the tendency tor the line or beat speed to

rotate toward the line ot operation This resulte in

better performance of the turbine at partbullloads

(2) he etf1o1ency eh111 tor the turbine beeomaa JDore

tlat at the top leading to a smaller max1JilWD effic1enc7

but e reater etticieney at other pointe of operation with

the insertion ot an auxiliary control ror the rate ot tlov

in the draft tube

(3) The power output of the turbine will increase at

over speed over gate conditione as well a at part gate

conditions with the proper amount or draft tube eonatr1cbull

tion or flow

(4) It is possible to eliminate at least partially

eddy type shock loss by tho introduction ot flow control

in the draft tube

BIBLIOGRAPBl

1 Addison Herbert A treatise on applied h-draul1cs New York Wiley 1954 724 Pbull

2 Allen o M and I A Winter middot Co111parative testa on experimental draft tubes Tranaact1ons ot the American ociety ot Civil Engineers 87t893bull970 1924

3 Barrows a E Water power engineering 3d ed ew York McGraw-Bill 1943 791 Pbull

Bovet G A Modern trenda in hydraulic turbine design4middot in Europe Tranaactions of the American Society ot Mechanical Engineera 75975bull993 1953bull

s Oreager William P and Joel D Justin Hydroelectrichandbook 2d ed New York Wiley 19$0 1151 Pbull

6 Daily Jamea w Hydraulic machinery Int Hunter Rouses Engineering hydraulics Hew York Wiley 19$0 p 8$8bull99

Daughertybull Robert L Bydraulie turbines ew Yorkbull7middot MoGrav-Hlll 1920 281 Pbull

8 Daugherty Robert L Inveat1gat1on of tne performance ot a reaction turbine ~anaactiona or the American Society ot Civil Engineers 7811270bull1304 1915

9 Davie L M Model and prototype testa Int Trend in hydraulle turbine practice symposium lranaactions ot the American Society ot Civil Engineers 1o63S3middot368 1941

lfJ Doland James J Hydro power engineering Hew Yorkbull Ronald 1954 209 Pbull

11 Gandy Theodore s and Elmer c Schacht Direct curshyrent motor and generator troubles operation and repair New York McGraw-Bill 1911 293 Pbull

12 Gibaon Arnold H Hydraulics and ita applications5th ed London Constable 1952 813 Pbull

58

13 Button s P Component loases in Kaplan turbinebull and The prediction of efficiency from model tests Probull coedings of the Institution or Mechanical Engineers168743-762 1954

14 Knapp R T~ Oavit t1on mechanics and its relation to the d sign or hydraulic equip ent Proceedings or tne Institution ot Mechanical Engineers 166150bull16) 1952

15 Langsdorf Alexander s Principles of direct curHnt mach1nee 5th ed New York r~cGrawbullH1ll 1940 746 Pbull

16 Lsrner Chester w Characteristica of modern hydraubull lie turbines Trans e~ions of the ~~erican Society ot Civil Engineers 66306-386 1910

17 Linsley Ray K Jr and Jobulleph B Franzin1 Eleshyments of hydraulic enginebullring New York McGrawshyBill 19$5 $82 Pbull

18 Mead Daniel w Hydraulic machinery llev York McGraw-Hill 1933 396 Pbull

19 ead Daniel w Water power engineering New York McGrawbullRill 191S 843 Pbull

20 Mockmore Charles A Part gate operation at water turbines Corvallis Oregon State College Department ot Civil Engineering 1933 11 numb leaves (Unpubshylshed typescript)

21 Mockmore Oharles A Flow characteristics in elbow dratt tubes Transactions of the Amez-ican Society ot Civil Engineers 103402middot464bull 1938

22 Moody L F Hydraulic machinery In c v Davis Handbook ot applied hydraulics New York McGrawshyHlll 1942 1082 Pbull

2) Ptau At-nold Hydrbullulie turbine handbook ld ed Milwaukee AllisbullOhalmers ManufactUIing Company 1948 70 Pbull

RheingalUI w J Recent developments in Francis turshybines Mechanical Engineering 74189-196 1952

25 Russell George E Hydraulica 5th ed New York Henry Holt 1942 466 Pbull

26 Safford A and E P- Hamilton American mixed tlow turbine and ita setting Tranampactions or the Amerieal Society of Civil Engineers 851237bull1)56 1922

27 bull Spannhake W1lhe1Dh Problems or modern pump and tur b1ne design Transactions of the American Society of Mechanical Engineers 56e22$-248 1934bull

28 Sutherlandraquo R A Better ethod or representing and middot tudying water turbine performance ~ansaetions ot thmiddote American Society of Mechanical Engineers 68t675bull 686 1946

29 Teats ot five models or draft tubes tor turbines Engineering News-Record Pbull 182-184 Aug 2 1923

30 White w M American hydztaulic turbines Mechanical Engineering S2t390bull39S 1930bull

31 White w M lhe hydraucGne rega1ner1 its developmentand appl1eat1ons 1n hydroelectric plants Meohanlobulll Engineering 43t37Sbull380 1921 middot

32 Winter I A Economic principlebull in designbull Int Trend in hydraulic urbin practice bull a ampoeiumTranaaot1ona ot the American Society ot Civil Engineerslo6332bull3S2 1941

33 Wiel1cenua G F Fluid mechan1ca or turbo-machineryNev York McGraw-Hill 1947 613 Pbull

APPENDICES

c

Appendix A

NOATIOB

A Angle between the absolute velocity vector and the tangent to the rwmer Subscripts 1 and 2 refel to entrance and exit ot the runner blade

B Angle between the relative 1elooity vector and the tangent to the rwmer Subscripta 1 and 2 refer to entrance and ezit or the runner blade

Angle between the tangent to the runner blade tip and the tangent to the runnel- Subscripts 1 and 2 reter to entrance and exit of the rt1rmer bladebull

Blade angle-gate opening conetant defined by equation (1)

e 09erall efficiency

g Gravitational acceleration assumed constant at 322 teet per second per second bull

H Turbine head detined by equation ($)

m Exit loss coeft1e1ent

Turbine speed expressed in revolutions per minute

Turbine speed under a constant head of 81 teet

specitic apeed of the turbine under a constant head ot 81 teet

p Power output in horsepower ot the tvbine

Power output of the turbine Ulder a constant head ot Sl teet

Pl- Pressure head at entrance to the tUlb1new

l1 Peripheral velocity ot the runneP Subacr1pta 1 and 2 refer to entrance and exit ot the JUnllampr blade

62

v Relative velocity reaulting trom the combination ot the absolute water velocity V and the runner periphshyeral velocity u Subscripts 1 and 2 refer to entrance and exit ot the runner blade

v] Relative velocity vector necessary to produce a tanbull gential entry into the runner blades

V Absolute water velocity Subscripts l and 2 refer to entrano and exit ot the runner blade

v2 Velocity head Subscripts 1 and 4 reter to the ~8 entrance to the turbine and the tail~ace wate~

w Unit weight ot water assumed constant at 624 pounda per cubic toot

V Weight rate ot flow in pounds per aeooncl

XX Velocity component ot ahook See Figule 2

Z Elevation head Subscripts 1 and 4 reter to entrance to the turbine and the taibace water surfacebull

Appendix B ORIGINAL DATA-Run

lfwnber

0-4-1 0-4-2 0-4-3 o-4-4 o-4-S o-4-6 0-4-7 0-4-8 0-4-9o-4-lo o-4-11 o-4-12 0-4-13

o-6-1 o-6-2 06-3 o-6-4o-6middotS o-6-6 o-6-7 o-6-8 0-6-9 o--6-lo o-6-11

Speed

rmiddot2middotbullmiddot(1)

336 38$ 451 S$9 620 669 6lt)$ 120 787 860 932

102imiddot109 bull

352 355 443middot 543middot 620 654AJs32

911 1001 1111

~essure Head rt (2)

410 410 416 426 431 43-7 439 44-9 452 467 482 soo $1 bull $

350 351 35middot7 )66 37-9 37-9 392 41 bull 3 43middot3 460 489

Elevation Bead

fjj $7 $7 $7 $7 $7 $7 51 57 5-15858 $8 58 56 56 $6565656 51 575As5a

Velocit Head

flj 07 07 07 06 06 06 06 os 05 os0404 03

09 09 oa o8 o8 os 07 07 06 o~o

Total Head rt ($)

47middot4 4A44 o 489 49-4 soo $02 $11 $14 $29 5imiddot45 2 576

41 bull $ 416 421 430 44middot3 44middot3 456 47-7 496 523551

Plow

lbtjec

326 324middot317 311 306 30029middot28 middotmiddot middot 386 275middot260 240 218

359 36~35 bull 349 345middot 339 330 318 300 273 240

Line Potential

vyqjbull 1060 1220 ~-0o 1920 2150 2000 2$60 2000 1940 18)015io11 o

1000 1100 139bull5 1760 1925 16$0 1620 1610 1540 1330 870

Line Current

amlscs 960 900 830 740 730655 70bull 0 530 660 600 5imiddot54 6 )60

982 930 860 780 ~3-545

79-5 74-5 670 560 370

P

Appendix B ORIGINAL DATA (Continued)

Run Number

Speed

Pbulltmiddotbullmiddot )

leasure Head ft(2

Elevation Head tt(J)

Velocity He-dfmiddotj

Total Bead tt($

Flow

lbstsec( )

Line Potential vo~ta( )

Line Current

amjs (sect

0bulllt)-1 0-9-2

3ll6 398

28o ~~1

$6 56

1o 10

346 347

390 365

1ooo 1190

aao 835

0-9-3 0-9-4 o-9-S

472 565 632

292 305 312

$6 s6 56

10 o9 o9

)$8 J7~o 37~7

381376 37o

1)6614oo 141o

820 ass ass o-9-6 0-9-7 0-9-8 o-9-9 0middot9-10

680 120 762 844 920

)24337346 366 390

56 $6 56 57 $7

09 os o8 oa 07

)89401 410 431454

367~ 357348 34o 322

1400 1J6o l36o 1310 1170

843 820 7957So 67~0

0-9-ll 0-912

1001 1100

41 bull 7 45-3

s 7 6~0

06 os 480 $18

299 268

980 65$

560 36~5

1-4-1 1-4-21-4-l1-4shy1-4-5 1-4-6 l-4-7 1 4-8 1-4-9 1-4-10 1middot4-ll 1-4bull12

354middot452 562 62q 674shy102 752 760- 863 932

1022 1100-

)82389 4014oa 416 41--7 423 428 44-2 45-7 486 49-2

51S757 51 5-7 5middot15zs sa $8 58 59

07 07 06 06 06 06 06 os o bull o 04 o J

446 45-)46middot4 471 ti7-9480 q86 491505 $19 548 55-4

)28 320 311 306 300 295 291 286 269 2582iimiddot21 bull

1080 14Lo 1550 153-5 1470 141-0 1385 1310 1310 1230 1120 855

970855 875 91-0 94~0 975 966 995 860 77-S 610 4fo

0 ~

Appendix B ORIGINAL DATA (Contirmed)-Run Speed Pressure Elevation Velocity Total Flow Line Line

Number Head Head Head had Potential Current rtjjmbull t~ bttec vyfs am~a12) ( ) ti fli 8

1-6-l $6 33$ $6 0bull9 400 364 1100 93 0 1-6-2 41 34laquo2 $6 oa 406 JS7middot iios a5s l-6-3 500 3~0 5bull6 os 356 1 1 o aos 41middot~1-6~4 35bull4 5-6 oa 41middot 352 16~0 82 0 5~1-6-5 5 bull 36_2 Sbull6 08 42bull6 349middot 161 ~ 0 86~0 1-6-6 622 366 $6 oe 43bull0 345middot 158 0 88~$ 16-A 649bull 37bull1 56 os 43-S 342middot 1570 895 1~- 386 57 07 46-0 192 ) 125A44 333middot 1-6-9 3) 404 5middot1 07 468 317 1620 675 1610 911 42-4 5-7 o6 48-7 298 168 0 61 0 1-6-11 999 451 56 os Sl ll 276 ~2-0 530 1-612 1115 485 58 04 54middot7 238 90 )3 0

1middot9-l 355 279 56 10 )45 385 1040 870 1-9-2 399 28J $6 10 )49 38$ 1140 86 5 l-9-3 ~ ao 291 56 ~0 35middot1 J8J_ JJ6o 815 1bull9-4 579 303 56 09 )68 375middot J4JO 830 l-9bullS 40- 313 )6 09 31middot8 370- 1460 82~0 1-9bull6 679 2) 56 09 3 bull8 364middot 1670 710 l-9-7 682 319 56 o9 384 ) 62 1460 79 5 l-9-8 724 33middot5 56 o8 399 3$6 bull 1480 76 -5 1-9-9 762 34middot3 $6 0 bull 8 407 )48 14910 13middotS 1-9-10 833middot )60 5middot7 os 42$ 339 144$ 686 1-9-ll 926 39middot1 5-7 07 455 318 1290 600 1-9-12 1000 41middot3 0-6 476 298 1115 510$ ~ 1middot9-13 1105 452 s o4 $14 2$6 710 )10

~

Appendix Bt ORIGDIAL J (Continued)

Run Speed Pressure Elevation Velocity Total Plow Line Line Number Head ltead Head jlamp$d P()ten~ibulll Current

r~~~m ft ft lbs~seo voltattj rgj twimiddot t 1 t2gt lt3 ou t ( rt

2-9-1 384 289 S 6 10 35 5 1400 1170 810 2-9-2 443middot 29$ $6 ltimiddot9 360 379middot 11(0 87$ 2-9-J 536 30bull 3 sc 09 )68 374middot 1)40 84 bull) 2-9-4 571 306 $6 09 3~1 372 120bull 0 955 2-9-5 623 316 S6 09 J l )6S UJSo 77$ 2bull9-6 669 327 S6 09 )92 )61 1240 905 2-9bull7 712 )39 56 os 40-3 351 12(0 86 bull0 2-9-8 ~5$~ J48 56 oa 412 348 1290 81 bull ) 2-9-9 04 )63 56 oa 42-7 339 12ltJO 76$ 2middotmiddot9-10 8$2 376 5middot1 07 440 33~- ~ o 710 2-9-11 955 394 5-1 o6 457 300 1100 506 2middot9-12 1000 421 $7 06 48middoti 295 1020 $18 2-9bull13 110~ 463 56 05 $2 267 620 3~0

oshy0

Appendix Gt CALCULATED DAgA

Turbine Run Generator Generator Turbine Turbine Efficiency Turbine Turbine Specit1c

Number OutputKWlt21

Loa~Jes KWlol

Outut K bull (H)

Input RP 12)

middot Percentlt13gt

Speed r~Jmiddot(

0ltput HP ~1

Speed r-m

( 6) middot

o-4-1 0middot4-2 0-4-3 0-4-4 0-4-5 0-4-6 O-qmiddot7o-4-8o-4-9 0-4bull10 0-4-11 o-4-12

1018 1o9a 1220 1)62J40214oa1J4oo 1357 1320 1164 997 718

046 o59 071 092 096 1071oo 134 104 100 109 107

14261sso 17)01948 2008 20322011 1999 19 09 1708 14-84 11o6

281279 27-7 276 215 273271 268 268 26h 258 24-5

soa 555 62$ 705 7)1145 742 74-6714645 51s 45-1

440 sos 585 720 195 sso sao 9$$ 985

1065 1135middot 1230

318 357 319 416 422 419412 39middot9 378 324 260 191

102 12bull4 148 191 21bull 3 22o 233 249 24924middot9 238 221

0-4middot13 418 104 699 228 306 1300 117 18)

o-6-1 982 045 1376 271 $08 496 376 124 o-6-2 o-6-3 G-6-4o-6-5 0-6-6

1023 1200 13 73 J415 139h

051 0middot66 oaa ()bull 96 088

14-39 1696 1958 2026 1986

276 27middot4 273 278 274

$20 61 8 717 7)0726

q95615745 8)5685

390 ll5middot3 sos soo 490

127 170 218 243 2$$

o-6-7 o-6-8 o-6-9o-6-lo

1288 1199 1032 7-45

o9o 094 09$ 096

1846 1733 1511 1128

274 276 271 260

67S 629559 43middot4

980 1085 1165 1245shy

436 )83316 21bull 7

266 276 270 239

0-6-11 322 1oo 566 2141 2JS 1350 101 177 0 --4

Appendix C CALCULATED DAlA ( Continued)-Run

Number Generator Generator

Out2ut Losaes xw LW- 12gt (lO)

Turbine Out2ut

ltPlJ

Turbine Inat lfP Jig)

Etpound1e1ency

PireentDl

Turbine Sed x-~m( 1

Turbine OutEut RPJl)

Turbine Specific

SeeedrIbullntbull

( 6)

o-9middot1 0-9-2 0-9-3 o-lt)-4 09-$ 0bull9-6 0-9-7 0-9-8 0-9-9 0-9-10 o-9-11 0-9-12

aao 994

111$ 1197 1206 1180 11)21081 982 784 5-49 2)9

0middot45oss o6$ 070 07$ 0-77 (l77 or~ o s06o 8 096

123~ 1402 1$80 1698 17bulllS 168$ 16bull18 ~middot5430 1151 a~J4 9

24middotgt24middot3248 25~25 260 260 259 267 266 26middot1 2S2

sos 577 63-7 671 676 650 621 60036J4

327 178

$) 610AlO 3$

92S 980

102$ 1070 1157middot 1230 1300 137Smiddot

44middot4 soo 523 ssomiddot 540so6 46-5 432 368 274 18~8

J46 176 21-1 255 2802s_A 28 289 288 265 231 168

1-4-1 1-4middot2 1-4-3 1-4-4 1-4-5 1-4-6 1-4-7 1-J-8 1-4~9 1-4-10 1-4-11 1-4-12

10bull48 1231 13-S6 1397 1)821375 1))8 1303 1127 953 683) 51

048 067 o7A07 0 bull79 oa1 oss o bullao osa 0lt)0 096 099

J468 1740 1921 1978 1958 19$1 1911 lSSi162 1)98 1045

603

266 264 262 262 261 2512$7 2$6 24middot7 24-3 233 217

551 660 13middot3155 75-6 7~-97 middot4 72$ 67 51middotJ 44middot9 21middot1

475 605 A4220

875middot 910 970_

1000 1090bull 1166 1243 1330

5816

44middot444middot5 430 427 412 392 329 273 188 l0-7

117 101 204 22$ 2)7245 2562sa 257251 222 179

a-C))

Appendix Ct CALCULATED -DATA ( Ocntinued)

1-6middot1 1023 o$2 14-41 26S 505 41~6 26~

54middot5 13middot3l-6-2 1201 067 1boo 625 47-9 17shy~middot41-6bull3 1296 oA9 1 middot43 26 9 700 so5 20bull 4 l-6-4 l3j5 o 0 19~09 268 71bull3 A5o 514 222 1-6-5 1) 5 o81 19(gt4 271 725 51-5 238 l-66 1398 081 198) 27-0 736 8 S13 252~-middot l-6j 1405 083 199i 211 733 885 $middot06 2$9 l-6 13middot9~ 103 2amp 0 279 71 8 985~ 467 ~-69 1228 1 bull 02 17-SS 270 661 109$ 407 ~3~ l-6bull10 1025 100 lSll 26i 573 1175middot 27~S32middot~l-ampu 153 1-00 llft3 26 444 1270 22 24bull8 1bull6-12 294 100 52a 231 22 3 1360 95 172

1-9bull1 904 048 1275 2J4Z $28 S4$ 459 1$2 1-92 98$ oss 13-92 24middot4 57-0 6JO 49bull1 176 1-9middot3 1110 066 1$76 24middot9 63middot4 I2o 536 21-7 l--9-4 1187 072 1685 251 66$ 5 $$ bull 0 261 1middot9-5 llltJ7 1710 25middot4 67-3 93$ 536 28~20-671middot9-6 1186 o 8 1708 25-7 67) 980 $15 2691-9- 1161 oBo 1660 2$middot3 6$6 990 508 29-1 l~- ll-32 oB) 16sect0 2$8 632 1030 471 291 1-9bull9 109$ oa5 2$7 614 1075 29S~middot 0 4imiddot41-9-10 9~91 oas 262 S$1 1150~ 3 o 292 1-9-11 o9o u57 12JiO 21gt 26-77middot74

-45 26sect ~middot91-912 $69 091 sas 25 middot3 1)0$ 196 2J-8 1-9-1) 220 098 426 2)9 178 1390middot 84 16 6

0 0

Appendx C CALCULATED DATA (Continued)

Turbine Run Generator Generator lurbine Turbine Eft1e1eney Turbine lurbine Spee1f1c

Number Output Losses Outit Input Speed Output SPed middot k_-V KW R _ H_bull_P Percent r Thm HP rpm_ (9) tlo) 11) middot (12 _) (lJI ( ) (1$ (14)

2-9-1 9--46 055 1)62 258 528 580 164 2-9-2 1024 056 248 58 4 665 4 9 191iimiddot48 4~middot0 2-9-3 1132 067 05 2$0 641 795 52q 237 2-9-4 1148 065 1027 2$1 -~8 845 525 252 2-9-5 11 77 oso 16-83 253 6 910~ 522 270 2-9 6 1122 071 1600 251 622 960 47-5 2722-9-A 1092 015 1562 257 608 1010 445 2z12bull9- 1052 079 1514 261 580 1060 41middot7 2 2 2middot9-9 986 o82 ]429 26) 542 1105 372 277 2-9-10 915 086 1340 268 500 1160 334 27-6 2-9-11 638 087 972 254 )81 1270~ 229 250 2-9-12 )28 090 828 259 )19 1295 179 226 2-9-13 192 094 383 2$ 6 150 1370 7 3 152

-3 0

Page 6: The Effect of A Variable Draft Tube Flow Area on the

bull bull bull bull bull bull bull bull bull bull bull

bull bull

bull bull

LIS~ OP_ __ ILLUSTRAfiOBS-middot

Fiere Page

1 13 $ Inch Reaction turbine bull bull bull bull bull bull bull bull bull bull 4

s bull bull bull bull bull bull bull bull bull bull bull bull

Plow Area bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull 4S

2 Turbine Runner Vector D1agrama and Shook Loaa Diaptama bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull 10

) Turbine PertoPmance CurYea bull bull bull bull bull bull bull bull bull bull 20

4 General View ot Teat Equipment bull bull bull bull bull bull bull 21

6 View ot Teat ut-bine bull bull bullmiddot bull bull bull bull bull bull bull bull bull 7 Teat Generator and Platform bull bull bull bull bull bull bull bull bull 27

8 Iutrument Board and Field Rheostat bull bull bull bull bull 27

9 Vlev ot Water lUteoatat bull bull bull bull bull bull bull bull bull bull 29

10 View or Water Rheostat bull 29

11 Vater Plow Diagram and Electrical Laout bull bull bull 30

12 Sketoh ot Draft ltlbe and Teat Inaerta bullbull bull bull 33

13 View ot Dratt Ube Inaer bull bull bull bull bull bull bull bull bull bull 34

14 Vlev ot Dr~t lube Iuert bull bull bull bull bull bull bull bull bull 34 lS Curves ot Generator Voltage Drop and Copper

Lose bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull 40 16 euvtee of Oenerator Stray Power Lobullbull bull bull bull 41 17 Turbine Charae ter1at1ca with lOOC Dl-att lUbe

18 Turbine Characteristicbull With 7SC Draft tube Flow Area bull bull bull bull bull bull bull bull bull bull bullbull bull bullbull 46

19 Comparleon Between 7S~ and 100 Pratt Tubbull Flow Areas ot Power and Etf1c1ency at OVer Gate Condition bull bull bullbullbull bull bullbullbullbullbullbull 47

bull bull

~ Q ILLt1SlATlOIS (Continued)

F1pe

20 Comparison Between 15 and 100~ Draft Tube Flow Areas of PoweP and Ett1c1enoy at Halt Gate Condition bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull 46

21 Oompu1aon Betwen S~ and 100~ Draft Tube Flow ANaa ot Po-r and Efflctency ab Ovbullbull Gate Condftimiddoton bull - bull bull bull bull - bull bull middot bull bull bull 49 Compar1aon ot Spec1tic Speeda tor 75~ middotand 10~ Draft Tube Flow Areae bull bull bull bull bull bull bull bull so

I

bull

filE EPPEOI OF A VARIABLE DRAFT TUBE FLOW AREA

ON THE PERFORMANltJE OF A REAOTIO TURBINE

Chapter l

IITRODUClIOH

A hrpose and Scope of Invst1pt1on

Present day control of reaction turbines is accombull

pl1ahed by the use of wicket gates immediately- preceding

the turbine runner These gates otter an interrelated conbull

- trol to the quantity and direction ot the water entering

t-he runner ie a change in the amount ot flow will rebull

middot ult in a change in direction This combined control leada

to loesee at all but the rated or design condition ot the

turbine (2$ Pbull )71)

This investigation dealt with an att mpt to better

turbine performance at all points of operation b y the

eatabliahment of separate controls over the rate of flow

and the d1J~ect1on ot the entering watebullbull

The only physical modification of the test tlutbine

was the insertion of flow restricting device in the dratt

tube

Ot primary interest were the trends in the change of

2

turbine performance with the amount ot draft tube tlow

area To this end complete turbine charaeteristiea were

not obtained tor 0ach device inserted in the draft tube

It was considered sutt1e1ent to obtain data tor the tull

speed range tor two representative gat openings one

greater and one less than the rated gate openingbull

Before proceeding with th report ot this 1nvest1gabull

t1on it 1a desirable to supply sa b ckground m terial

on reaction tw-blnes and their dratt tubes

B Raot1on 1rbinea

A hydraulic turbine is a device for converting the

energy in water to eohanical energy (6 Pbull 93lbull96S) furbull

b1nes may be loosely grouped into one of three elasse

impulsmiddote 1 reaot1on or propeller

An impulse turbine normally operates under a high head

and with a relatively sma~l amount ot watel in the converbull

sion or kinetic nergy to mechanical energy The propeller

turbine utilizes pressure energy to develop mechanical

energy while under a low head and p ss1ng a large amount of

waver

The reaction turbine lies somewhere between these two

extremes It changes both pressure and kinetic energy

while oper ting under a medium head with a moderate ount

opound water An example or a reaction turbine is pietur d in

Figure 1

lhe terms of high low small and so tomiddotrth are only

relative in sense A turbinebulls class1f1 eat1on is depenfent

upon its hoad rate of diacharge and speed of rot tion A

useful index tor turbine comparison (5 Pbull 825) is termed

specific speed and this ia a function of the rated ipeed

power output and head or the turbine The common range in

values ot speoitic speed ($ Pbull 826 ) tor each type ot tlirshy

bine is

Impulse J to SS tor one nozzle)Reaction bull 22 to 80 Propeller - 85 to 170

The development of t he reaction turbine began in the

early part or the nineteenth century (26 Pbull 1217bull1)6)

The trst efficient inward tlow turbine was de igned by

James B Francis an American in 1649bull For many years

turbine design was a matter of cutbullandbulltry in America an4

pure mathematical analysis 1n Europe It was not until the

two schools began exchanging ideas in the l$tter halt ot

the n1neteenth century that pronounced advancement was made

in the field

ObTioual7 the primary pux-pose ot any turbine inatallabull

t1on is t he production of power Added to this is the

restriction that the production or power must necessarily

be a controlled process An example of this is where the

turbine is direct-connected to an electric generator which

4

Figure 1 - 135 Inch Reaction Turbine

5

must operate at a constant speed or rotation even though _

the power demand ohangos In thiamp case the turbine nuet

be eap~able or producing a range of power output yet menshy

ta1n e eonetant speed

Speed regulation of the turbine iv accomplished by

means ot a governor (23 Pbull 24bull3-7) bull The contr-ol or regulashy

tion 1s indirect that i s the governor actually exereiaabull

control over the water in order to JJaintain e given speed

Co-ntrol over- the turbine end bence its speed and

power is the function ot a ring of movable wicket gates

located just upsttteam of the turbine runner These w1eket

gates 1n the process of opening and closing upon eeeh

0~1ar in a rotational manner actually control the amount

velocity and direction of tne water passing throu~~ them

C Draft Tubes

It has been found that the effeetive head on a reae

1l1on middotturbine is increased with the addi timiddoton of a draft tube

(3 Pbull 256bull264) Tne draft tube does thin by~

(1) Making a greater presaure d~op across the turbine

possible by the creation of a negative pressure at the

discharge or the runner and

2) DeoreaGing the k1net1e energy lost by increasing

the eross sectional area at exit

he draft tube permits the turbine runner to be

6

located above the tail race water surface without the

sacrifice of head However cavitation will cause pitting

of the turbine if the difference in elevation is too great

A common maximum elevation difference is 19 feet although

this figure is quite subject to modification between difshy

ferent installations (3 p middot 264-266)

There are many different types or draft tubes in use

today the choice or type being largely a matter or

economics (2$ p 368-370) A very common type particushy

larly among the smaller units is vertical with flaring

sides However the angle of flare is limited by the possishy

bility of separation of the flow from the sides In order

to achieve a certain discharge area the length of the tube

may be such as to require a great deal of excavation In

oases or this sort the cost of this excavation must be

balanced against a more elaborate design that does not

require as much excavation Other draft tubes in use

include the elbow hydracone and spreader types

Despite the differences found in construction and

design the draft tube must accomplish the desired objecshy

tives while offering a good hydraulic geometry to the flow

passing through it An inefficient draft tube defeats its

own purpose

Ohapter II

DISCUSSION ~ TURBINE LOSSES

A General

lhe head that 1a actually utilized by the turbine 1a

less than the effective bead as defined by equation ($) by

the amount that 1a lost due to mechanical and hydraulic

reasons

Mechanical loaaea are a function or the turbine 8p$ed

fhis ia not a lineaz- function but varies eomewhere between

N and N2 (3- Pbull 224)

Hydraulic losses encounteled in turbines ma- be subshy

divided aa to the location or occurrence (3 p 225-227) aa

fOllOW$S

(1) Penstock and scroll case

(2) Wicket gates

(3) Between wicket gates and turbine runner

(4) Runner passages

(5) Runner exit into draft tube

(6) Draft tube and

(7) At exit from the draft tube

The flow in the penstock scroll case wicket gates

runner passages and draft tube may be envisioned as

examples of flew in conventional pipes elbows and convergbull

1ng passages If this comparison may be made it could be

assumed that the losses encountered in these locations

would be proportional to vn ~ value ot N is normally2g

aesU111ed to be 2

he losses encountered between the wicket gates an4

the turbine runner and exit lossos are special cases which

will be discussed separately

B Shock toes_

The flow betwe n the wicket gat outlet and the runner

blade entrance is or particular 1nt rest because no direct

comparison vith common flow situations is obvious

Conaider the vector diagram (7 Pbull 7576) in Figure 2

The veetoo v1 is the absolute entering velocity of the

water and is fixed in magnitude and direction by the setbull

ting or the wicket gates The vector l11 1e the peripheztal

velocity of the runnel which tol any given turbine 1e

dependent only upon the turbine rotational speed The

combination of these two vectors ylelda the third vector

v1 which is the relative entering velocity ot the water

nere is only one setting ot the wicket gates for a

given turbine a peed that will produce an angle B1 which

coincides with the blade angle B1bull At other gate settings

the vector v1 will rotate and change in magnitude in such a

9

t ehion that B1 will beoome either greater or 1 sa than B1bull Th1 give rise to tbe phenomenon term d shock loasft

If B1 1a greater than B1 the relative ent ring veloebull

ityt v1 will have a compon~nt opposing the forward motion

of the runner The shock loss could be typified bullbull that

occasioned by direct impact or the water 0n the blade- If

E1 is lese than a] the vector l will overshoot the blade

and the flow will tend to eddy around the forward portion

or the blade tip

The shock loss can then be either due to impact or

eddying flow Since the area norm 1 to the radius at outlampt

of the w1eket gftee is essentially equ 1 to the area normnl

to the rad1u~ at the inlet to the turbine runner the combull

ponents ot vl and vl perpendicular to ul will b approxishy

mately equal This leads to the conclusion that xxbull ~epresenting the shock vector 1 parallel to Ulbull

For either the impact or eddy case the trigonometric

law of $1nee leads tot

XX

bull ul - sin (Bi-Al) vl eln Bi

It it 1a assumed that the energy lost in the shock 1a

the Telocity head ot the shock component XX then

10

VELOCITY VECTOR DIAGIWI

TYPES OF SHOCK LOSS

xbull X

IMPACT BDDJ

XX 1a Teloc1t7 caponent ot shock

Figure 2 - ~bine Runner Vector Diagram$ and Shock Loss Diagrams

11

2 shock loss (XX gt2g

C =sin (BimiddotAl)Let (1)sin Bi

(UlmiddotCV1)2Then shock loabull (2)- 2g

For a given gate opening C ia a constant ranging

from about 14 to 10 For a well designed wheel it is to middot

be expected that C would be approximately equal to U1V1

at rated conditions ie at point of maximum efficiency

This point will occur in the neighborhood of 3~ to 78

gate opening for moat turbines For overgate conditions

the angle A1 becomes larger so the value of C would

decrease For gate openings below rated conditions t he

angle A1 decreases and C would decrease One could expect

a fairly uniform decrease in t he value of C as the gate is

closed from t he overgate position

The velocity v1 is approximately constant for any

turbine speed since the area and rate of flow both decrease

fairly uniformly However for a given gate opening the

velocity V1 will decrease with increased turbine speed

From the foregoing comments and equation (2) the

following trends can be established

(1) For constant turbine speed the shook loss curve

will be close to parabolic in shape concave upward and

have its maximum near t he point of complete gate closure

--

12

and its minimum near the rated gate position

(2) For conatant gate opening the shook loss curve

will approximate a symmetrical parabola with its vertex

the point of minimum loas located at the rated condition

of operation (7 Pbull 79)

c Exit Loas

It can be seen from Figure 2 that the exit loss from

the turbine would be v222g if no draft tube were present

The addition of a draft tube permits the gradual reduction

of velocity by an increase in cross sectional area between

the exit of the runner and the exit from the draft tube

The exit loss and the frictional loss encountered in

the draft tube may be placed together in the expression

m va2 (3)Exit Loss ~---2g

For the ideal case of no friction in the draft tube

m is equal to the square of the ratio of the area at exit

from the runner to the area at exit from the draft tube

In an actual turbine installation however friction

will change the value of m (7 p 84-85) to somewhere

between that for the ideal case and a maximum ot 10

In the interest of maintaining a minimum exit loss

the turbine should be designed and operated so the velocity

V2 will be minimum This will occur when the discharge

13

vector is at right angles to the tangent to the runnerbull

ie the angle A2 1e ninety degree bull It ia to be expected

that this condition will be tultilled near the design con~

d1t1ons ot the ~bine

Current design praetiee 1 to have a small component

ot v2 in th$ direction of turbine rotation at rated condibull

tion$ ltS p 938)

For a constant turbine speed the d1seharg or exit

loss is ess nti lly a constant

For a constant gate opening the exit lo s curve is

aptrroximately a symmetrical pa~abola with ita vert x the

point or minimum loss located at a slightly lowe~ speed

th n the turbine rated speed (7 Pbull 79)

Chapter III

PROPOSAL OP ALlERMAlE MFTBO 0 CO TROL-A lz ~ Location 2 Control

Thua tar only practice and theoretical aspects appemiddotrbull

taining to present day turbinea have been d1acuaaed It

haa been presented that control over the ~bine ia ezerbull

oiaed b y manipulation of the wicket gatea located 11101led1bull

ately preceding the runner These gate - upon rotation

modify both the magn1tu4e and the direction ot the entering

velocit7 Moreover it has be n shown that a simultaneous

change in these two variables leads to inefficient operabull

tion by the introduction of shock loss he farther the

point of operation a from the rated conditione the more

aerioua ia the ahock loss encountered

Any attempt to better turbine pertorance at other

than rated conditione and tbne flatten the top ot the

etticieney hill8 must concentrate upon the lessening ot

the ahock loaa It 1a a aumed that 1 provement in the

scroll case gates and runners would lequ1re sueh pertecbull

tion 1n machine work and metal$ as to be prohibitively

expensive

It ie surmised that any move to elblinate eYen parbull

tially the shock loss would require separate control ovel

l$

the flow and gate exit angle Since it is improbable that

d1~ect1on could be controlled at any location other than

where the gatea are situated in current turbines it will

be assumed that guide vanes will be necessary regardlesa or the method used to control the rate of flow

The primary purpose ot th se guide vanes 1s that or control over the direction ot the incoming water They

should be free to rotate in much the same manner as ordibull

nary wicket gates in order to exercise control over th

turbine speed

If the rate ot tlov is to be controlled elsewhere it

must be modified either in the penstock or the draft tube

Devices that could be used are standard valves gates

variable orifices variable venturi sections and associated

flow regulating schemes

Alauming it were decided to locate such a device upbull

stream of the turbine it would be necessary to allow disbull

tance tor the flow picture to become reestablished prior to

entry to the turbine A contused flow making transit of

the turbine passages would only contribute additional loesbull

ea Such a distance allowance would be perbapa 20 to So

diameters (2$ Pbull 119-123) In large penstocka th1a would

repreaent a considerable distance Which from the viewbull

points ot convenience and control would be undesirable

Attempts to ascertain the effect or additional tlov

16

reduc ion at the wicket gatctsmiddot wae ade 1n the lfadraulioe middot

Laboratory of Oregon St middot te College in 1933 (20) Three

d1tterent thode ot reducins the tlow were t~ied

(l) Locking in the cloeed position pairs or wicket

gatea located opposite to eaeh o~er on the -periphery ot

the wheel

(2) Locking adjacent gates in an open position by

inserting blocks of wood between them and

()) Suocess1vely looking adjacent gates in the closed

position

The results indicated a arked reduction in both power

and efficiency when compared to the curves tor normal gate

operation However it was demonstrated that it was poae1bull

ble to ahitt the power and tfieiency curve ill relation to

turbine apeed lbis important feature will be diacussed

later

ihe main conclusion of the investigation was that conbull

trol by the conyent1onal wick t gates was auper1or to other

methode egtt control exercised at the gates the aelvebullbull

It would app$ar that the bebullt location tor flow conshy

trol would be in the draft tube since none of the objecbull

tiona prev1ously mentioned wou~d eziat there

As bas been stated previously the sole object or the

17

18

turbine is to produce power as etfic1ently as possible

The equation tor the power output of a turbine () Pbull 227)

PaWHe HP (4)55o bull bull Assuming the head 1a constant and a g te located in

the draft tube decreases bhe rate ot flow the power eu

only be increased if the etticiency increases

The ettective head Gn the turbine 1s conventionally

d r1ned as the difference between the auma ot the elevashy

tion head pressure head and velocity head at the entrance

to the turbine casing and the tailrace ($ Pbull 872)

lt ie recognized that the theoretical treatment ot

shock loss as given is highly approximate and serves only

to dictate certain trenda For example the area at xit

rom the wicket g tea CfUl be measuPed with some exactness

but there exists no guarantee that the wateP particles will

complet-ely fill the apace oz- will exit at the establiahed

g te angle The same can be said of the exit trom the

runner blades AssUIlptiona were implied which would indishy

cate that all water particles passing a given croea section

ampH traveling at the same velocity in the same direction

the e alone are autt1c1ent to show 11m1tationa in a theoretbull

1eal approach to the problem

Assume a turbine with ordinary wicket gates tor oonbull

trol compared gainst the same turbine with a gate in the

18

draft tttbe tor supplampment1ng control or the rate ot rlow

Let it also be assumed that the two turbines are opershy

ating at the same point It 1s desirable to predict relabull

tive performance of the two turbines 1 this point of

operation is such that edd7 s hook loss ot reasonable proshy

portions is present in the fir t turbine

~ tull erteot of the shock loss will be exper1 need

by- the fir t turbine

lhe second turbine will derive certain advantages 11

the gate in the draft tube is adjusted to reduce the tlov

1n the proper amount Since they vary a the square ot

the veloo1t7bull the lossabull in the aeroll case wiomiddotket gate

and runner passages will decx-ease aetet-r1ng to Figure 2 1

it can be seen that a decreased velocity v1 w-ill reduce the

eddy shock losa

The ent loss in the dJtaft tube of the second turbine

will be the sum ot the tr1ct1onal loss and the velocity

head at ex1t The velocity head dissipated will be greater

due to the closing action or the gate but the reduoed

t~ictional loss which ia a tunction ot the rate of tlow1

will partially balance this

It 1a entirely possible that the net reduction in

losses in the second turbine will lead to a greater ettibull

oiency and more power output than 4eYeloped by the first

turbine

19

In Figure 3 the plot ot power output against turbine

speed for Curv A~ represents the typical family of curvea

tor a reaction turbine Th b st sp ed is the locus ot

points connecting maximum eft1oiency at each gate opening

The operating speed is the coZUJtant turbine apeed which

passes through the point ot maximum efC1ciencr of the turbull

bine The plot of turbine efficiency against power output

for Curve A is also ahown

It the turbine with flow regulation in the dratt tube

oan demonstrate superior power and efficiency at part loads

the effect would be the same as a shifting or the power

curves toward the condition shown fop Curve B 11 Thisbull

illustrates th ultimate case of the uperpoait1on of best

and operating speeds It will be noted that the pet-form~

of the turbine ot Ourve Bu 1a better than that of CUrve

A at part loads because of ita ability to sustain a relabull

tively high etticienoy ovel a Wider range of power output

o Reguireaegts tort Test Velitication

It is desired to deterra1ne the effect on the turbine

performance b) the addition of a gate in the dratt tube

Th step in the teit will bet

(1 To determine the power output and efficiency ot

the turbine tor wicket gate settings above and below rated

conditione for a wide range ot speed

20

CURVEAbull

TURBINE SPSBD TURBID SPEKD

POIBR OOTPOl

Figure 3 - Turbine Performance Curves

21

22

(2 peat (l) with the gate installed in the drat

tube

(3) middot Converting middot all data to a constant head compare the

powere and effioiencies at the same wicket gate setting and

turbin speed tor the two cbullses

If the ddition or the gate indicates an improvement

in power output and efficiency and the powe~ curve shifts

to the right along the turbine apeed scale the advantage

ot draft tube con~ol of the flow will hav been demonshy

strated

Chapter IV

A E9J11pment

ih turbine used in this test is lJ 5 1nch Pelton

reaction turbine with a rated output ot 30 horsepower under

a head of 56 feet at a speed ot 720 reYolutiona per minute

Views of this turbine are hovn in Figures S and 6 The

turbine is installed on a concrete pad located over an open

channel in the Hydraulics Laboratory at Oregon State Colshy

lege The date of manufacture of this turbine was 1915

The water was delivered to the turbine from a sump

reservoir by two pumps operating 1n parallel Each pump 1a

an 8 inch Pelton double suction centrifugal pump witb a

rating of l$00 gallons per minute at a head ot 75 teet with

a speed ot 1175 revolutions per minute Tbe inlet tlange

ot tne turbine is $pprox1mately 18 feet above the center

line of the pump

A direct current generator was coupled to the turbine

to receive tne power d veloped as shown in Figures 4 and 7 The generator is a Spr gue Electrodynamometer rated at SS horsepower with a speed range of 7$0 to l$00 revolut1one

per minute The classification is type LO 26A 2)0 volta

Figure 5 - View of Test Turbine

Figure 6 ~ View of Test Turbine

and 149 amperes lbe generator ti ld was aepar tely

excited using direct current from a motor g n r tor ampt

(l$ p 4~8)

The power output of the generator waa dissipated in

the water rheostat (3 p 488-489) shown in Figures 9 and

10 The galvanized tank contain d water ot variable d pth

on an electrode ot cast iron m aauring 1bull x 1 x 1

In the initial installation of the turbine it was

intended that the power output should be measured with a

Prony brak bull For th purpoa68 or this teat it was decided

that the brake was too instable and the generator was

substituted The platform for raising the generator the

nee asary two teet for alignment was built out of available

material In this case heavy laminated wood blocks reiashy

torced with other timbers were used and bolted through the

concrete deck (11 Pbull 36-$7)

Due to the light concrete deck the lack ot mas in

the platform and the slight misalignment in the flexible

coupling ao e vibration waa encountered It seemed to

ncr aae linearly to a maximum at the speed of bout 750

revolutions per minute Above this speed no vibPation was

noticeable The vibration waa not se~ere and does not

appear to have materially affected the test results

26

B Intrumentat1on ~ eaeur1ng Devices

The pressure head at inlet to the turbine vaa meaave4

bymeane ot two )6 inch waterbullmeroury manometerbull connected

in series as shown in Figure 8

The terminal voltage ot the generator vas meaeured by

a laboratory voltDleter with a range to )00 yolta and callbull

brated to within 15 Yolta

The armature current bull and hence the line current was

measured by a laboratory ammeter with a range to 150 amperea

and callbrated to w1 thin o 7S amperes

Tae rate ot tlow was established by weight and time

meaeurementa The weighing ank has a capacity ot 121 000

poundsJ the weight belng indicated by Toledo direct reading

scales Timing was done with a hand atop watch with clivibull

aion ot 02 second

he ~ater level in the tailrace was dete~1ned by a

hook gauge lhie was read to the nearest 001 toot

The turbine and generator speeds were eaaured by a

hand tachometer The technique of almost cont1nuoua readbull

ings of the speed gave an error ot no more than 5 revolubull

tiona per minute

c Operational Procedure

Atter the water level in the aump was checked to

insure an adequate auppl7 the puapa were primed and

27

Figure 7 - Test Generator and Plattorm

Figure middot8- Instrument Board and Field Rheostat

28

started After venting they were valved for operation 1n

parallel

The motor generator set was started to supply the

field current and the circuit breaker was closed Water

wa added to the water rheostat to the level shown in

Figure 10 ~ field current wae minimized by cutting in

all the f ield resistance in the field rheostat of Figure 8

The l2 inch gate valve shown in Figures 5 and 6 waa

slowly opened and the turbine and generator brought up to

speed The 12 inch gat valve and turbine were vented and

the pumps were checked to insure neither had lost ita prime

lhe water rheostat offers very steady load 1f the

water level is essentially constant and the water temperabull

ture 1a fixed () p 488~89) In order to maintain this

constant temperature it was decided not to circulate the

water in the rheostat but rather to allow the water to

boil thua achieving the desired result A standing wave

was set up on the face ot the electrode by the boiling

action but a atable load was eatablished except at very

low water leYels where th11 agitation led to fluctuationa

in the line current

After putting the turbine and generator on the line

maximum power was dissipated in the rheostat by redueing

the turbine speed to between oSO and Soo revolutions per

minute Salt vas added to the rheoetat wat r to increasemiddot

29

Figure 9 - View of Water Rheostat

Figure 10 - View of Water Rheostat

Separate Field ExcitationFrom Motor-Generator set Compound Water-Mercury

---shy

re Manometer

I Q)

~ 0

~

Book Gauge

Open Channel

I

Slap Reservoir

Figure 11 - Wat~r Flow Diagram and Electrical Layout

31

waiting pe~iod ot perhaps an h~ followed

while the boiling point or the water wbulls reacbe4 During

this ti+ne the manometer was vented end eheoked electrical

measur1ng 1nstlUments were connected end the hook gauge was

adjusted tor elevation

It required about two- houtte tor the generator to reach

its normal operating tempe-ratu~e_ After the water in the

rheostat and generator had reached their operating temperabull

turea it was possible to begin the taking of data

The only vaPiable which was controlled wee the turbineshy

generator speed However the upper l1ut1t of safe line

current was slightly over 100 ampJilPampPes and the eireuit

breaker would open when the current reached lOS ~ere bull

Control was exercised by means ot regulating the water

level and salt 1n the water rheo tat and the res1stsnoe of

the tield rheost t~

The etfeet ot each type ot regulation on the three

variables is shown below

Volta Aaperebull Speed

Inc Dec Inc Dee~ Inc Dec

Wa~e1 Level Inc Dec~ X

X X X X

X

Salt Concentration

Inc Dec X

X X X X

X

field Resistance

Inc Dec

X X

X X

X X

32

Jlot all methods gave the ame amount ot change in a

given variable and a period of experiment and trial led to

the following scheme starting the rune with the lowest

turbine speed the water level was high with a high amount

ot salt and the field resistance was cut completely out

Aa it became necessary to increase the speed tor each

aucceasive run either cutting in t he field resistance

decreasing the salt concentration or lowering the Vater

level would produce the desired result However decreasbull

1ng the salt concentration had to be done Without a net

gain in water which led to a tluahing procedure that was

not particularly good because cold water was introduced

which required time to heat to the boiling point Cutting

1n additional field resistance was a good method but th1a

increased the amperage possibly to the point of opening

the circuit breaker Lowering the water level was aatiashy

factol1 until the level got too low causing the current

fluctuation previously mentioned Actually it turned out

that a combination of lowering the water level and cutting

field resistance in would carry the speed from ita minimum

to 1ts maximum value it the proper choice were made each

time the speed waa to be changed At the conclusion of

each aet of runs at a high speed the water level would be

low and the field resistance high

33

TURBINE

PAD AND DECK

TAILRACE

WATER SURFACamp

CONCRETE

DRAFT TU1B INSERTS

7 5( DRAFr TUBE

FLltJI ARIA

5~ DRAFT TUBE

FLOI ARSA

Figure 12 - Sketch of Draft Tube and Test Inserts

34

Figure 13 - View of Draft Tube Insert

Figure 14 - View of Draft Tube Insert

D c __ ~s_middot hedu_le of

A number was assigned to each run The fi~st number

applies to the draft tube tlow areas

1 bull 100~ flow area or 0~ oonatriction

2 - 7S tlow area or 2$ conatr1ct1on

3 SoC flow area or so~ constriction

The second number refers to the wicket gate openings

9 over gate opening

6 bull intermediate gate opening

4 bull one h lt gate opening

The third number 14entif1ea the location of the particular

1Wl in a set ot rona made at a given dratt tube tlow area

and wicket gate opening

fnua run number 1bull4bull10 would identity this as the

tenth run ot a set made at halt gate with 75 ot the draft

tube t1ow area

Rune w re made tor a g1yen dratt tube condition

Firat tor tull 41-aft tube flow area seta ot rune were

made for the overgate halt gate and intermediate gate

conditione An insert was placed in t he draft tube and

rune based on the same gate conditions were made tor the

7S~ draft tube flow area case The insert was then changed

to allow only $~ draft tube flow area

The inserts are sketched 1n Figure 12 and photographed

ln Flgurea 13 and 14 They oonaisted of circula~ segments

36

or l2 ineh plywood mount 4 on wooden legs 10 inches high

The 1nse7te were placed in position and secured by th use

ot a-clamps on the legs and the outside ot the bottom of

the draft tube The obvious disadvantage to this method

waa the neoeasity tor draining the water from the tailrace

tor a change ot 1naert The advantage vas of course the

simplicity ot design and construction

Chapter V

DATA-A Original Data

The normal data-taking crew consisted or two men

Assuming adjustments having been made to secure a certain

turbine speed (aee section on Operational Procedure) one

man would take semi-continuous speed readings with the hand

tachometer until a state or rotational equilibrium was

reached This could be only a period or two minutes up to

ten or tifteen minutes As soon as steady speed was

assured the data taking would begin The second man went

to the weighing tank Where a minimum ot three weighingamp

were made The requirement was to get three consecutive

readings such that the ditterence between tbe smallest and

largest time did not exceed 04 seconds The time to

collect a given weight ot water was then assumed to be the

arithmetic average of the three times He then went to the

hook gauge determined the hook elevation and then

recorded the data on the data sheets The first man meanshy

while had taken readings of the line voltage line current

and manometers and checked the turbine speed by multiple

readings During the length of the run all values were

38

checked to determine mean values for recording

The minimum length of one run was about five minutes

If one or more measure ants tended to drift during the run

all values wer discarded and a new run began as soon aa

qu111br1um was stabl1shedo

B -0-al_e_u_l_a_t--d Data

The h d on the tu~bine 1 defined by

($)

The maxtmwm velocity V4 was equal to about o8 tampet per

secon4 which makes it a negligible quantity when converted

into velocity head

An engineerbulla level was used to deterine the d1ffePshy

ence 1n elevation between the compound water-mercury manoshy

meter and the hook gauge Using this value the equation

for turbine bead becomes

where z4 is the hook gauge reading

The rate of flow 1 cent

w weight or water collected average time to collect

The inlet velocity v1 vas calculated by dividing the

weight rate or flow by the specific weight of water and the

)9

area ot ~e inlet pipe This was equivalent to dividing

the weight rate of flow by 490 Then the power input to the turbine is equal to

WHpin rri

10 (6)

Also

(P ~ut) Turbine

(P out) + Generator

(P lost) Generator

The power output of the generator is simplJ the

produot ot the terminal voltage and the armature (line)

curPent The power lost in the generator can be subdivided

into copper losses and stray power losses lo evaluate

these cunes based on losses of an identical generator

11leampsured by the Department ot Mechanical Engineering were

used The loss curves are reppoduced in part in Figures

15 and 16

Determination ot generator losses proceeds as tollowau

(1) From Figure 15 detem1ne the vo1tage drop in the

armature circuit using the temperatures of 1220 F and the

meaaured current

(2) The induced voltage is t~e sum of the terminal

voltage and the voltage drop 1n the armature circuit

() Entering the induced voltage and the turbine speed

into Figure 16 the stray power loss can be determined

(4) The copper lose can be evaluated from Figure 1$

using the measured current and the temperatlll-e of 1220 P

40

25 ~------~--------~--------~------~

U) -U) - 20

f-4 ~

-~ -gt 0

0

VOLTAGE DROP

~ - i -

- bullbullbull bull - -middot-middot -+ ~- + -t--+ ~ - ~ middotbull ~-~ middott- -+----- _ -4 middotmiddot- --~-+-t---r~~ ~--+t-t- - ---t-c-++~-ulf--

0 50 75 100

Figure 15 - Curves of Generator Voltage Drop and Copper Loss

41

1200

1000

800

600

800

0

0

~-

middot--~ 1shy --1 + bull l

100

I -

150 200

IIDOOED VOLTAGB (VOLTS)

Figure 16 - Curves of Generator Stray Power Loss

_ j

-bullshy -L---- shy middot -shy

250

- r

42

(5) The generator los os equal the sum of the eopp r

loss and stray power loss

~e efficiency or the turbine is taken as

etticiency u e =P out (8)Pin

~ample pound Determ1n1gg turbine Power Output

The following data are taken trom that ot Run 1-9-1

Line voltage 1040 volts Line current 870 amperesSpeed 355 revolutions per minute

The induced voltage 1a determined as follows

Line voltage 1040

Voltage drop 90 using Figure 15 with line current of 870 amperes and temperature ot 122 degrees)

Induced Toltage 1130 volta

The power output of the turbine is determined as follows

Generator output 90$0 (line voltage z line current)

Oopper loss 7 (using Figure 15 with line current of 870 amperes and temperatUe or 122 degrees)

Stray power lose 470 (using Figure 16 with speed ot 355 revolutions per miDUte and induced voltage or 1130 volts)

Turbine power output 9527 vatta

or turbine power output 1s 12z2 horsepower

43

The conversion of the calculated data to a constant

head is based on the conventional assumption of constant

efficiency regardless of turbine head For a constant head

ot 81 teet a purely arbitrary figure the tollowing relashy

tionships are ass1lJiled to be true

I ____L (9) (i)l72

(10)

For these two values the specific a peed may be combull

putedt

N t Jt VPt (11)8 243

Chapter VI

~RESULTS

A -Pr_e_ae_n_t_a_t_t_o~n g Reaultbull

Graphical presentation ot the results ot this te1t

are given as follows

Figure 17 -Turbine characteristics with 100~ dratt

tuba 1low area

Figure 18 - Turbine characteristics with 7S dratt

tube tlow area

Figure 19 bull Comparison ot power and etticiency at

over gate conditions between 100 and

75~ draft tube flow area

Figure 20 bull COZQparison of power and ettic1ency at

halt gate conditions between 100~ and

7S~ draft tube flow area

Figure 21 bull Comparison of power and etticiency at

over gate condition between 100~ and

So dratt tube tlow area

Figure 22 - Comparison in variation ot apec1t1c

speed between 100 and 75~ dratt tube

tlow area

50

45

20

-bull - 1--shy40

bull J-~ 30

~ ex

~ 20

~~ ~ -)q

I

~ - _

- -

10~ OF DRAFT TUBE FL(Jif AREA

CONSTANT HEAD OF 8l FEST10

POIER OUTPUT EFFICIENCY SPECIFIC SPEED

0 ~--------------_--------~------~------~ 400 600 800 1000 1200 1400

TURBINE SPEED (RPM)

Figure 17 - Turbine Char~cteristics with 100 Draft Tube Flow Area

50

46

-bulllle

~ 7 ~ OF DRAFt TUBE FLOW AREA

0 -~~-rl C05STAMT BEAD OF 81 mET 1J~

POIER OOTPUT ---+- ---o ~_H EFFICIDCY ~ I shy

bull ql SPECIFIC SPEKD - ~ -

bull ~ J 10 L rmiddotr- r- -

bullz- I

~~ 30 ~~--~----~~-

20 ~ ~ middot-shy

26

~~ 25

~0 ~r-----i (

Tbull -bullshy

400 600 800 1000 1200 1400

TURBINE SPEED (R PK )

Figure 18 -Turbine Characteristics with 75 Draft Tube Flow Area

47

EFFICIENCY 60

1-----shy

-~ 50~--~--~~-~middot middot middot middot r~-~----~~~~---4~-r~-~~gtt

II

POWER~ J ~ bull bull

u I

sH

40~------+-------+---- -~~--~~-~~~~

~----~rl 1 bull

I

I

0~--------------~------_------~--------

~ -OVER GATE CONDITION

COIJSTANT HEAD OF 81 FEET

0 o 10~ DRAFt TUBE

_-- _ 7~ DRAFT TUBamp FLON AREA II

10_~-----+--------r-------r----~~

400 600 800 1000 1200 1400

TURBINE SPEED (RPM)

Figure 19 middot - Comparison between 75 and 100 Draft Tube Flow Areas of Power and Efficiency at Over Gate Conshydition

48

t

bull --4 r ~- ~ middot~

70 1-----------+-~~~~~+middot ~ ~~ middot middot -~~--~~--------~~----~-+1

-~-

Atbull bull

lla-

60

amp0

40

20

10

oampOO

t _ - - ~-+- - -~-

l2 GATB COJIDITIOJJ

COJISTABT HJW) OF 81 JBET

o 0 lOQ( DRAFl TUB8 FLOI AREA

e-- - e 75 DRAFT TUBE FLOW AREA

800 1000

- r-

~

TURBIbull SPBIID (RPII)

Figure 20 - Comparison between 75 and 100 Draft Tube Flow Areas of Power and Efficiency at Half Gate Conshydition

49

60

50

-40

bull 30

IIQbull

20

10

0

400

- t - ~

EFFICIENCY

_J bull - bull bull

~ r r middot t -+ shy L -t -

OVER GAD COliDITIOI

CONSTABT BEAD OF 8l FBB

o o 10~ DRAFt TUBE FLOI ADA middot--- 5~ DRAF TUBE FLQPi AREA

600 800 1000 1200

Figure 21 -Comparison between 50~ and 100~ Draft Tube Flow Areas of Power and Efficiency at Ove~ Gate Conshydition

50

25

20

15

10

0

Figure 22

~- T -4 -t- -l --~-

t-~ I

middot --~- t ~---- _ __ _ + --

----~- --r-- --

~-=J-~-=-~ -==~ _ ~- -- ---f---1 - shy

CONSTANT HEAD OF 81 FEBT

o--o 1~ DRAFT TUBE FLltll AREA

75C DRMT TUBK FLCIJ AREAmiddot--middot-middot 600 800 1000

TURBINE SPEED (RPK)

Comparison of Specific Speeds for 75 and 100 Draft Tube Flow Areas

51

B Discussion 2 Result

Consideration of Figures 17 and 18 indicates the

overall eftioi ncy pattern or hill is significantly or

rounded for the 7$~ flow area than for the 100~ flow area

bia implies a greateP efficiency is possible at speeds

leas than or greater than design speed with an insert in

the draft tube However the muilDum efficiency is lemiddotas

Direct comparison at over gate conditions is made in

Figure 19 ~e same general trend is noted tor both the

etticiency and power curves for the 7$~ flow area case

The eurves show higher values at overspeed than do the

correaponding cWvea for the 100 flow area case It ia

not clear whether the curves have been shifted by the dratt

tube constriction or whether the curves simply bulge past

the normal curves at both overspeed and underspeed condishy

tions The power curves apparently peak near the aeme

point bullalthough maximum power is still obtained with the

normal draft tube area

For the comparison at halt gate operation shown in

Figure 20 a general improvement has apparently been made

by restriction of the draft tube flow area At every speed

the etticienoy and the power is greater for the restricted

tlow case The two ett1o1ency curves and two power curvea

are practically parallel throughout the speed range ot

teat

As the flou aroa i e decreased still farther a s1gn1

ticant change appears Reterr1ng to Figllle 211 tor the $0

flow area curves it a obvious that exit losses have

become excessive at the overgate condition because the

efficiency and power are everywhere leas than tor the case

of normal draf t tube area

Earlier it was pointed out t hat 1t the r esult s 1nd1bull

eated an increase in both power and ef tieiency- t hen it

could be assumed tha t the additional los s i ntroduced with

the draft tube insert is less than the diminished losses

due to leas shock losa and water passage losses For the

places where both the efficiency and power have been

increased we can assume that the insert has improved turshy

bine performance

For the places where the power haa been decreased

nothing can be said as to the elimination of ampbock loss

because the new lose present with the drat tube insert has

overshadowed any gains in eftecti Ve head upatJ-eam of the

insert

Near the peak of the efficiency hill howeve~ it may

be pointed out t hat shock loaa ie a minimum with a normal

draft tube and the insert merely adds an additional loss

with the resultant decrease in maximum efficiency tor the

7$~ flow area case

Perhaps the most s1gn1ticant set of eurves is shown aa

53

Figure 22 In this graph values of specific speed tor the

75 and 100~ flow area cases for both over gate and one

halt gate openings are plotted against turbine speed At

every speed and both gate openings the value ot specific

speed for th 75~ flow area case is greater than that for

the 100 t1ow area ease

Since the head is a constant for both situations this

may be interpreted in either of two ways trom equation

(11)

(1) For the same turbine apeed restriction of the

draft tube t1ow area resulted in greater turbine power

(2) For the same power amputput the turbine with 75~

draft tube flow area operated at a greater speed than did

the one with 100 flow area

Since the required diameter of a turbine varies

inversely with the speed the second interpretation could

be stated such that a smaller turbine could be used to

develop the same power output

Whether viewed trom the aspect of increased power

greater speed or reduced size the performance of the turshy

bine with reduced draft tube flow area is superior to that

with the nolmal flow are in the draft tube

The curve of specmiddotific speed versus turbine speed for

the so draft tube flow area case at over gate cond1t1ona

was not included in Figure 22 This curve lies below that

for the 100~ flow area c se at all speeds

In elaboration ot the second interpretation of Figure

22 attention is directed to the relative magnitudes ot

increased apee1f1c speed tor the two gate openings Assumbull

ing that the increase in specific speed implies a shift ot

the power curve to the right along the turbine speed scale

the power curve would be shifted more tor tbe halt gate

opening than tor the over gate opening

It thia trend could be extrapolated to the other gate

openings the tendency can be seen tor the line ot beat

speed to rotate toward the line of the operating speed as

illustrated in FigtU-e ) The advantage of this has already

been discussed

This particular turbine has a low specific speed tor a

reaction turbine Aa the rated value of apecitic apeed tor

reaction turbines increases the line ot beat speed departs

even more radically from the line of operating bullpeed It a

test similar to this were conducted on a reaction turbine

ot gleater specific speed it is pJobable t hat the rotation

ot the line of beat apeed would become more p~onounced

The scheme used in th1a teat had two obvious dr wbull

backs The first was the decision to leave all the wicket

gamiddottes installed tor all conditions ot the draft tube

These gates predominated in control of the tlow The

inserts added to the draft tube merely acted as auxiliary

55

contrGla

The aecond drawback was the choice or device to place

in the draft tube The reasons foll selection of this type

of device have been previously mentioned It is to be

anticipated that adaptation ot dratt tube flow control

would result 1n a better device for an actual turbine

installation Such apparatus might take the form of a

pneumatic bladder or a h7drau11oally operated variable

venturi section in the draft tube It is conceivable that

the gate as used in this test might be adapted also

Chapter VII

OONCLtJSIOfS

From the results of this test the following eonolubull

e1ona aa to the effect ot a variable draft tube flow area

on the performance or a r action turbine may be drawn

(1) The effect ot a variable draft tube tlow area 1a

generally favorable upon the operat1Gn ot a reaction turbull

bine because or the tendency tor the line or beat speed to

rotate toward the line ot operation This resulte in

better performance of the turbine at partbullloads

(2) he etf1o1ency eh111 tor the turbine beeomaa JDore

tlat at the top leading to a smaller max1JilWD effic1enc7

but e reater etticieney at other pointe of operation with

the insertion ot an auxiliary control ror the rate ot tlov

in the draft tube

(3) The power output of the turbine will increase at

over speed over gate conditione as well a at part gate

conditions with the proper amount or draft tube eonatr1cbull

tion or flow

(4) It is possible to eliminate at least partially

eddy type shock loss by tho introduction ot flow control

in the draft tube

BIBLIOGRAPBl

1 Addison Herbert A treatise on applied h-draul1cs New York Wiley 1954 724 Pbull

2 Allen o M and I A Winter middot Co111parative testa on experimental draft tubes Tranaact1ons ot the American ociety ot Civil Engineers 87t893bull970 1924

3 Barrows a E Water power engineering 3d ed ew York McGraw-Bill 1943 791 Pbull

Bovet G A Modern trenda in hydraulic turbine design4middot in Europe Tranaactions of the American Society ot Mechanical Engineera 75975bull993 1953bull

s Oreager William P and Joel D Justin Hydroelectrichandbook 2d ed New York Wiley 19$0 1151 Pbull

6 Daily Jamea w Hydraulic machinery Int Hunter Rouses Engineering hydraulics Hew York Wiley 19$0 p 8$8bull99

Daughertybull Robert L Bydraulie turbines ew Yorkbull7middot MoGrav-Hlll 1920 281 Pbull

8 Daugherty Robert L Inveat1gat1on of tne performance ot a reaction turbine ~anaactiona or the American Society ot Civil Engineers 7811270bull1304 1915

9 Davie L M Model and prototype testa Int Trend in hydraulle turbine practice symposium lranaactions ot the American Society ot Civil Engineers 1o63S3middot368 1941

lfJ Doland James J Hydro power engineering Hew Yorkbull Ronald 1954 209 Pbull

11 Gandy Theodore s and Elmer c Schacht Direct curshyrent motor and generator troubles operation and repair New York McGraw-Bill 1911 293 Pbull

12 Gibaon Arnold H Hydraulics and ita applications5th ed London Constable 1952 813 Pbull

58

13 Button s P Component loases in Kaplan turbinebull and The prediction of efficiency from model tests Probull coedings of the Institution or Mechanical Engineers168743-762 1954

14 Knapp R T~ Oavit t1on mechanics and its relation to the d sign or hydraulic equip ent Proceedings or tne Institution ot Mechanical Engineers 166150bull16) 1952

15 Langsdorf Alexander s Principles of direct curHnt mach1nee 5th ed New York r~cGrawbullH1ll 1940 746 Pbull

16 Lsrner Chester w Characteristica of modern hydraubull lie turbines Trans e~ions of the ~~erican Society ot Civil Engineers 66306-386 1910

17 Linsley Ray K Jr and Jobulleph B Franzin1 Eleshyments of hydraulic enginebullring New York McGrawshyBill 19$5 $82 Pbull

18 Mead Daniel w Hydraulic machinery llev York McGraw-Hill 1933 396 Pbull

19 ead Daniel w Water power engineering New York McGrawbullRill 191S 843 Pbull

20 Mockmore Charles A Part gate operation at water turbines Corvallis Oregon State College Department ot Civil Engineering 1933 11 numb leaves (Unpubshylshed typescript)

21 Mockmore Oharles A Flow characteristics in elbow dratt tubes Transactions of the Amez-ican Society ot Civil Engineers 103402middot464bull 1938

22 Moody L F Hydraulic machinery In c v Davis Handbook ot applied hydraulics New York McGrawshyHlll 1942 1082 Pbull

2) Ptau At-nold Hydrbullulie turbine handbook ld ed Milwaukee AllisbullOhalmers ManufactUIing Company 1948 70 Pbull

RheingalUI w J Recent developments in Francis turshybines Mechanical Engineering 74189-196 1952

25 Russell George E Hydraulica 5th ed New York Henry Holt 1942 466 Pbull

26 Safford A and E P- Hamilton American mixed tlow turbine and ita setting Tranampactions or the Amerieal Society of Civil Engineers 851237bull1)56 1922

27 bull Spannhake W1lhe1Dh Problems or modern pump and tur b1ne design Transactions of the American Society of Mechanical Engineers 56e22$-248 1934bull

28 Sutherlandraquo R A Better ethod or representing and middot tudying water turbine performance ~ansaetions ot thmiddote American Society of Mechanical Engineers 68t675bull 686 1946

29 Teats ot five models or draft tubes tor turbines Engineering News-Record Pbull 182-184 Aug 2 1923

30 White w M American hydztaulic turbines Mechanical Engineering S2t390bull39S 1930bull

31 White w M lhe hydraucGne rega1ner1 its developmentand appl1eat1ons 1n hydroelectric plants Meohanlobulll Engineering 43t37Sbull380 1921 middot

32 Winter I A Economic principlebull in designbull Int Trend in hydraulic urbin practice bull a ampoeiumTranaaot1ona ot the American Society ot Civil Engineerslo6332bull3S2 1941

33 Wiel1cenua G F Fluid mechan1ca or turbo-machineryNev York McGraw-Hill 1947 613 Pbull

APPENDICES

c

Appendix A

NOATIOB

A Angle between the absolute velocity vector and the tangent to the rwmer Subscripts 1 and 2 refel to entrance and exit ot the runner blade

B Angle between the relative 1elooity vector and the tangent to the rwmer Subscripta 1 and 2 refer to entrance and ezit or the runner blade

Angle between the tangent to the runner blade tip and the tangent to the runnel- Subscripts 1 and 2 reter to entrance and exit of the rt1rmer bladebull

Blade angle-gate opening conetant defined by equation (1)

e 09erall efficiency

g Gravitational acceleration assumed constant at 322 teet per second per second bull

H Turbine head detined by equation ($)

m Exit loss coeft1e1ent

Turbine speed expressed in revolutions per minute

Turbine speed under a constant head of 81 teet

specitic apeed of the turbine under a constant head ot 81 teet

p Power output in horsepower ot the tvbine

Power output of the turbine Ulder a constant head ot Sl teet

Pl- Pressure head at entrance to the tUlb1new

l1 Peripheral velocity ot the runneP Subacr1pta 1 and 2 refer to entrance and exit ot the JUnllampr blade

62

v Relative velocity reaulting trom the combination ot the absolute water velocity V and the runner periphshyeral velocity u Subscripts 1 and 2 refer to entrance and exit ot the runner blade

v] Relative velocity vector necessary to produce a tanbull gential entry into the runner blades

V Absolute water velocity Subscripts l and 2 refer to entrano and exit ot the runner blade

v2 Velocity head Subscripts 1 and 4 reter to the ~8 entrance to the turbine and the tail~ace wate~

w Unit weight ot water assumed constant at 624 pounda per cubic toot

V Weight rate ot flow in pounds per aeooncl

XX Velocity component ot ahook See Figule 2

Z Elevation head Subscripts 1 and 4 reter to entrance to the turbine and the taibace water surfacebull

Appendix B ORIGINAL DATA-Run

lfwnber

0-4-1 0-4-2 0-4-3 o-4-4 o-4-S o-4-6 0-4-7 0-4-8 0-4-9o-4-lo o-4-11 o-4-12 0-4-13

o-6-1 o-6-2 06-3 o-6-4o-6middotS o-6-6 o-6-7 o-6-8 0-6-9 o--6-lo o-6-11

Speed

rmiddot2middotbullmiddot(1)

336 38$ 451 S$9 620 669 6lt)$ 120 787 860 932

102imiddot109 bull

352 355 443middot 543middot 620 654AJs32

911 1001 1111

~essure Head rt (2)

410 410 416 426 431 43-7 439 44-9 452 467 482 soo $1 bull $

350 351 35middot7 )66 37-9 37-9 392 41 bull 3 43middot3 460 489

Elevation Bead

fjj $7 $7 $7 $7 $7 $7 51 57 5-15858 $8 58 56 56 $6565656 51 575As5a

Velocit Head

flj 07 07 07 06 06 06 06 os 05 os0404 03

09 09 oa o8 o8 os 07 07 06 o~o

Total Head rt ($)

47middot4 4A44 o 489 49-4 soo $02 $11 $14 $29 5imiddot45 2 576

41 bull $ 416 421 430 44middot3 44middot3 456 47-7 496 523551

Plow

lbtjec

326 324middot317 311 306 30029middot28 middotmiddot middot 386 275middot260 240 218

359 36~35 bull 349 345middot 339 330 318 300 273 240

Line Potential

vyqjbull 1060 1220 ~-0o 1920 2150 2000 2$60 2000 1940 18)015io11 o

1000 1100 139bull5 1760 1925 16$0 1620 1610 1540 1330 870

Line Current

amlscs 960 900 830 740 730655 70bull 0 530 660 600 5imiddot54 6 )60

982 930 860 780 ~3-545

79-5 74-5 670 560 370

P

Appendix B ORIGINAL DATA (Continued)

Run Number

Speed

Pbulltmiddotbullmiddot )

leasure Head ft(2

Elevation Head tt(J)

Velocity He-dfmiddotj

Total Bead tt($

Flow

lbstsec( )

Line Potential vo~ta( )

Line Current

amjs (sect

0bulllt)-1 0-9-2

3ll6 398

28o ~~1

$6 56

1o 10

346 347

390 365

1ooo 1190

aao 835

0-9-3 0-9-4 o-9-S

472 565 632

292 305 312

$6 s6 56

10 o9 o9

)$8 J7~o 37~7

381376 37o

1)6614oo 141o

820 ass ass o-9-6 0-9-7 0-9-8 o-9-9 0middot9-10

680 120 762 844 920

)24337346 366 390

56 $6 56 57 $7

09 os o8 oa 07

)89401 410 431454

367~ 357348 34o 322

1400 1J6o l36o 1310 1170

843 820 7957So 67~0

0-9-ll 0-912

1001 1100

41 bull 7 45-3

s 7 6~0

06 os 480 $18

299 268

980 65$

560 36~5

1-4-1 1-4-21-4-l1-4shy1-4-5 1-4-6 l-4-7 1 4-8 1-4-9 1-4-10 1middot4-ll 1-4bull12

354middot452 562 62q 674shy102 752 760- 863 932

1022 1100-

)82389 4014oa 416 41--7 423 428 44-2 45-7 486 49-2

51S757 51 5-7 5middot15zs sa $8 58 59

07 07 06 06 06 06 06 os o bull o 04 o J

446 45-)46middot4 471 ti7-9480 q86 491505 $19 548 55-4

)28 320 311 306 300 295 291 286 269 2582iimiddot21 bull

1080 14Lo 1550 153-5 1470 141-0 1385 1310 1310 1230 1120 855

970855 875 91-0 94~0 975 966 995 860 77-S 610 4fo

0 ~

Appendix B ORIGINAL DATA (Contirmed)-Run Speed Pressure Elevation Velocity Total Flow Line Line

Number Head Head Head had Potential Current rtjjmbull t~ bttec vyfs am~a12) ( ) ti fli 8

1-6-l $6 33$ $6 0bull9 400 364 1100 93 0 1-6-2 41 34laquo2 $6 oa 406 JS7middot iios a5s l-6-3 500 3~0 5bull6 os 356 1 1 o aos 41middot~1-6~4 35bull4 5-6 oa 41middot 352 16~0 82 0 5~1-6-5 5 bull 36_2 Sbull6 08 42bull6 349middot 161 ~ 0 86~0 1-6-6 622 366 $6 oe 43bull0 345middot 158 0 88~$ 16-A 649bull 37bull1 56 os 43-S 342middot 1570 895 1~- 386 57 07 46-0 192 ) 125A44 333middot 1-6-9 3) 404 5middot1 07 468 317 1620 675 1610 911 42-4 5-7 o6 48-7 298 168 0 61 0 1-6-11 999 451 56 os Sl ll 276 ~2-0 530 1-612 1115 485 58 04 54middot7 238 90 )3 0

1middot9-l 355 279 56 10 )45 385 1040 870 1-9-2 399 28J $6 10 )49 38$ 1140 86 5 l-9-3 ~ ao 291 56 ~0 35middot1 J8J_ JJ6o 815 1bull9-4 579 303 56 09 )68 375middot J4JO 830 l-9bullS 40- 313 )6 09 31middot8 370- 1460 82~0 1-9bull6 679 2) 56 09 3 bull8 364middot 1670 710 l-9-7 682 319 56 o9 384 ) 62 1460 79 5 l-9-8 724 33middot5 56 o8 399 3$6 bull 1480 76 -5 1-9-9 762 34middot3 $6 0 bull 8 407 )48 14910 13middotS 1-9-10 833middot )60 5middot7 os 42$ 339 144$ 686 1-9-ll 926 39middot1 5-7 07 455 318 1290 600 1-9-12 1000 41middot3 0-6 476 298 1115 510$ ~ 1middot9-13 1105 452 s o4 $14 2$6 710 )10

~

Appendix Bt ORIGDIAL J (Continued)

Run Speed Pressure Elevation Velocity Total Plow Line Line Number Head ltead Head jlamp$d P()ten~ibulll Current

r~~~m ft ft lbs~seo voltattj rgj twimiddot t 1 t2gt lt3 ou t ( rt

2-9-1 384 289 S 6 10 35 5 1400 1170 810 2-9-2 443middot 29$ $6 ltimiddot9 360 379middot 11(0 87$ 2-9-J 536 30bull 3 sc 09 )68 374middot 1)40 84 bull) 2-9-4 571 306 $6 09 3~1 372 120bull 0 955 2-9-5 623 316 S6 09 J l )6S UJSo 77$ 2bull9-6 669 327 S6 09 )92 )61 1240 905 2-9bull7 712 )39 56 os 40-3 351 12(0 86 bull0 2-9-8 ~5$~ J48 56 oa 412 348 1290 81 bull ) 2-9-9 04 )63 56 oa 42-7 339 12ltJO 76$ 2middotmiddot9-10 8$2 376 5middot1 07 440 33~- ~ o 710 2-9-11 955 394 5-1 o6 457 300 1100 506 2middot9-12 1000 421 $7 06 48middoti 295 1020 $18 2-9bull13 110~ 463 56 05 $2 267 620 3~0

oshy0

Appendix Gt CALCULATED DAgA

Turbine Run Generator Generator Turbine Turbine Efficiency Turbine Turbine Specit1c

Number OutputKWlt21

Loa~Jes KWlol

Outut K bull (H)

Input RP 12)

middot Percentlt13gt

Speed r~Jmiddot(

0ltput HP ~1

Speed r-m

( 6) middot

o-4-1 0middot4-2 0-4-3 0-4-4 0-4-5 0-4-6 O-qmiddot7o-4-8o-4-9 0-4bull10 0-4-11 o-4-12

1018 1o9a 1220 1)62J40214oa1J4oo 1357 1320 1164 997 718

046 o59 071 092 096 1071oo 134 104 100 109 107

14261sso 17)01948 2008 20322011 1999 19 09 1708 14-84 11o6

281279 27-7 276 215 273271 268 268 26h 258 24-5

soa 555 62$ 705 7)1145 742 74-6714645 51s 45-1

440 sos 585 720 195 sso sao 9$$ 985

1065 1135middot 1230

318 357 319 416 422 419412 39middot9 378 324 260 191

102 12bull4 148 191 21bull 3 22o 233 249 24924middot9 238 221

0-4middot13 418 104 699 228 306 1300 117 18)

o-6-1 982 045 1376 271 $08 496 376 124 o-6-2 o-6-3 G-6-4o-6-5 0-6-6

1023 1200 13 73 J415 139h

051 0middot66 oaa ()bull 96 088

14-39 1696 1958 2026 1986

276 27middot4 273 278 274

$20 61 8 717 7)0726

q95615745 8)5685

390 ll5middot3 sos soo 490

127 170 218 243 2$$

o-6-7 o-6-8 o-6-9o-6-lo

1288 1199 1032 7-45

o9o 094 09$ 096

1846 1733 1511 1128

274 276 271 260

67S 629559 43middot4

980 1085 1165 1245shy

436 )83316 21bull 7

266 276 270 239

0-6-11 322 1oo 566 2141 2JS 1350 101 177 0 --4

Appendix C CALCULATED DAlA ( Continued)-Run

Number Generator Generator

Out2ut Losaes xw LW- 12gt (lO)

Turbine Out2ut

ltPlJ

Turbine Inat lfP Jig)

Etpound1e1ency

PireentDl

Turbine Sed x-~m( 1

Turbine OutEut RPJl)

Turbine Specific

SeeedrIbullntbull

( 6)

o-9middot1 0-9-2 0-9-3 o-lt)-4 09-$ 0bull9-6 0-9-7 0-9-8 0-9-9 0-9-10 o-9-11 0-9-12

aao 994

111$ 1197 1206 1180 11)21081 982 784 5-49 2)9

0middot45oss o6$ 070 07$ 0-77 (l77 or~ o s06o 8 096

123~ 1402 1$80 1698 17bulllS 168$ 16bull18 ~middot5430 1151 a~J4 9

24middotgt24middot3248 25~25 260 260 259 267 266 26middot1 2S2

sos 577 63-7 671 676 650 621 60036J4

327 178

$) 610AlO 3$

92S 980

102$ 1070 1157middot 1230 1300 137Smiddot

44middot4 soo 523 ssomiddot 540so6 46-5 432 368 274 18~8

J46 176 21-1 255 2802s_A 28 289 288 265 231 168

1-4-1 1-4middot2 1-4-3 1-4-4 1-4-5 1-4-6 1-4-7 1-J-8 1-4~9 1-4-10 1-4-11 1-4-12

10bull48 1231 13-S6 1397 1)821375 1))8 1303 1127 953 683) 51

048 067 o7A07 0 bull79 oa1 oss o bullao osa 0lt)0 096 099

J468 1740 1921 1978 1958 19$1 1911 lSSi162 1)98 1045

603

266 264 262 262 261 2512$7 2$6 24middot7 24-3 233 217

551 660 13middot3155 75-6 7~-97 middot4 72$ 67 51middotJ 44middot9 21middot1

475 605 A4220

875middot 910 970_

1000 1090bull 1166 1243 1330

5816

44middot444middot5 430 427 412 392 329 273 188 l0-7

117 101 204 22$ 2)7245 2562sa 257251 222 179

a-C))

Appendix Ct CALCULATED -DATA ( Ocntinued)

1-6middot1 1023 o$2 14-41 26S 505 41~6 26~

54middot5 13middot3l-6-2 1201 067 1boo 625 47-9 17shy~middot41-6bull3 1296 oA9 1 middot43 26 9 700 so5 20bull 4 l-6-4 l3j5 o 0 19~09 268 71bull3 A5o 514 222 1-6-5 1) 5 o81 19(gt4 271 725 51-5 238 l-66 1398 081 198) 27-0 736 8 S13 252~-middot l-6j 1405 083 199i 211 733 885 $middot06 2$9 l-6 13middot9~ 103 2amp 0 279 71 8 985~ 467 ~-69 1228 1 bull 02 17-SS 270 661 109$ 407 ~3~ l-6bull10 1025 100 lSll 26i 573 1175middot 27~S32middot~l-ampu 153 1-00 llft3 26 444 1270 22 24bull8 1bull6-12 294 100 52a 231 22 3 1360 95 172

1-9bull1 904 048 1275 2J4Z $28 S4$ 459 1$2 1-92 98$ oss 13-92 24middot4 57-0 6JO 49bull1 176 1-9middot3 1110 066 1$76 24middot9 63middot4 I2o 536 21-7 l--9-4 1187 072 1685 251 66$ 5 $$ bull 0 261 1middot9-5 llltJ7 1710 25middot4 67-3 93$ 536 28~20-671middot9-6 1186 o 8 1708 25-7 67) 980 $15 2691-9- 1161 oBo 1660 2$middot3 6$6 990 508 29-1 l~- ll-32 oB) 16sect0 2$8 632 1030 471 291 1-9bull9 109$ oa5 2$7 614 1075 29S~middot 0 4imiddot41-9-10 9~91 oas 262 S$1 1150~ 3 o 292 1-9-11 o9o u57 12JiO 21gt 26-77middot74

-45 26sect ~middot91-912 $69 091 sas 25 middot3 1)0$ 196 2J-8 1-9-1) 220 098 426 2)9 178 1390middot 84 16 6

0 0

Appendx C CALCULATED DATA (Continued)

Turbine Run Generator Generator lurbine Turbine Eft1e1eney Turbine lurbine Spee1f1c

Number Output Losses Outit Input Speed Output SPed middot k_-V KW R _ H_bull_P Percent r Thm HP rpm_ (9) tlo) 11) middot (12 _) (lJI ( ) (1$ (14)

2-9-1 9--46 055 1)62 258 528 580 164 2-9-2 1024 056 248 58 4 665 4 9 191iimiddot48 4~middot0 2-9-3 1132 067 05 2$0 641 795 52q 237 2-9-4 1148 065 1027 2$1 -~8 845 525 252 2-9-5 11 77 oso 16-83 253 6 910~ 522 270 2-9 6 1122 071 1600 251 622 960 47-5 2722-9-A 1092 015 1562 257 608 1010 445 2z12bull9- 1052 079 1514 261 580 1060 41middot7 2 2 2middot9-9 986 o82 ]429 26) 542 1105 372 277 2-9-10 915 086 1340 268 500 1160 334 27-6 2-9-11 638 087 972 254 )81 1270~ 229 250 2-9-12 )28 090 828 259 )19 1295 179 226 2-9-13 192 094 383 2$ 6 150 1370 7 3 152

-3 0

Page 7: The Effect of A Variable Draft Tube Flow Area on the

bull bull

~ Q ILLt1SlATlOIS (Continued)

F1pe

20 Comparison Between 15 and 100~ Draft Tube Flow Areas of PoweP and Ett1c1enoy at Halt Gate Condition bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull bull 46

21 Oompu1aon Betwen S~ and 100~ Draft Tube Flow ANaa ot Po-r and Efflctency ab Ovbullbull Gate Condftimiddoton bull - bull bull bull bull - bull bull middot bull bull bull 49 Compar1aon ot Spec1tic Speeda tor 75~ middotand 10~ Draft Tube Flow Areae bull bull bull bull bull bull bull bull so

I

bull

filE EPPEOI OF A VARIABLE DRAFT TUBE FLOW AREA

ON THE PERFORMANltJE OF A REAOTIO TURBINE

Chapter l

IITRODUClIOH

A hrpose and Scope of Invst1pt1on

Present day control of reaction turbines is accombull

pl1ahed by the use of wicket gates immediately- preceding

the turbine runner These gates otter an interrelated conbull

- trol to the quantity and direction ot the water entering

t-he runner ie a change in the amount ot flow will rebull

middot ult in a change in direction This combined control leada

to loesee at all but the rated or design condition ot the

turbine (2$ Pbull )71)

This investigation dealt with an att mpt to better

turbine performance at all points of operation b y the

eatabliahment of separate controls over the rate of flow

and the d1J~ect1on ot the entering watebullbull

The only physical modification of the test tlutbine

was the insertion of flow restricting device in the dratt

tube

Ot primary interest were the trends in the change of

2

turbine performance with the amount ot draft tube tlow

area To this end complete turbine charaeteristiea were

not obtained tor 0ach device inserted in the draft tube

It was considered sutt1e1ent to obtain data tor the tull

speed range tor two representative gat openings one

greater and one less than the rated gate openingbull

Before proceeding with th report ot this 1nvest1gabull

t1on it 1a desirable to supply sa b ckground m terial

on reaction tw-blnes and their dratt tubes

B Raot1on 1rbinea

A hydraulic turbine is a device for converting the

energy in water to eohanical energy (6 Pbull 93lbull96S) furbull

b1nes may be loosely grouped into one of three elasse

impulsmiddote 1 reaot1on or propeller

An impulse turbine normally operates under a high head

and with a relatively sma~l amount ot watel in the converbull

sion or kinetic nergy to mechanical energy The propeller

turbine utilizes pressure energy to develop mechanical

energy while under a low head and p ss1ng a large amount of

waver

The reaction turbine lies somewhere between these two

extremes It changes both pressure and kinetic energy

while oper ting under a medium head with a moderate ount

opound water An example or a reaction turbine is pietur d in

Figure 1

lhe terms of high low small and so tomiddotrth are only

relative in sense A turbinebulls class1f1 eat1on is depenfent

upon its hoad rate of diacharge and speed of rot tion A

useful index tor turbine comparison (5 Pbull 825) is termed

specific speed and this ia a function of the rated ipeed

power output and head or the turbine The common range in

values ot speoitic speed ($ Pbull 826 ) tor each type ot tlirshy

bine is

Impulse J to SS tor one nozzle)Reaction bull 22 to 80 Propeller - 85 to 170

The development of t he reaction turbine began in the

early part or the nineteenth century (26 Pbull 1217bull1)6)

The trst efficient inward tlow turbine was de igned by

James B Francis an American in 1649bull For many years

turbine design was a matter of cutbullandbulltry in America an4

pure mathematical analysis 1n Europe It was not until the

two schools began exchanging ideas in the l$tter halt ot

the n1neteenth century that pronounced advancement was made

in the field

ObTioual7 the primary pux-pose ot any turbine inatallabull

t1on is t he production of power Added to this is the

restriction that the production or power must necessarily

be a controlled process An example of this is where the

turbine is direct-connected to an electric generator which

4

Figure 1 - 135 Inch Reaction Turbine

5

must operate at a constant speed or rotation even though _

the power demand ohangos In thiamp case the turbine nuet

be eap~able or producing a range of power output yet menshy

ta1n e eonetant speed

Speed regulation of the turbine iv accomplished by

means ot a governor (23 Pbull 24bull3-7) bull The contr-ol or regulashy

tion 1s indirect that i s the governor actually exereiaabull

control over the water in order to JJaintain e given speed

Co-ntrol over- the turbine end bence its speed and

power is the function ot a ring of movable wicket gates

located just upsttteam of the turbine runner These w1eket

gates 1n the process of opening and closing upon eeeh

0~1ar in a rotational manner actually control the amount

velocity and direction of tne water passing throu~~ them

C Draft Tubes

It has been found that the effeetive head on a reae

1l1on middotturbine is increased with the addi timiddoton of a draft tube

(3 Pbull 256bull264) Tne draft tube does thin by~

(1) Making a greater presaure d~op across the turbine

possible by the creation of a negative pressure at the

discharge or the runner and

2) DeoreaGing the k1net1e energy lost by increasing

the eross sectional area at exit

he draft tube permits the turbine runner to be

6

located above the tail race water surface without the

sacrifice of head However cavitation will cause pitting

of the turbine if the difference in elevation is too great

A common maximum elevation difference is 19 feet although

this figure is quite subject to modification between difshy

ferent installations (3 p middot 264-266)

There are many different types or draft tubes in use

today the choice or type being largely a matter or

economics (2$ p 368-370) A very common type particushy

larly among the smaller units is vertical with flaring

sides However the angle of flare is limited by the possishy

bility of separation of the flow from the sides In order

to achieve a certain discharge area the length of the tube

may be such as to require a great deal of excavation In

oases or this sort the cost of this excavation must be

balanced against a more elaborate design that does not

require as much excavation Other draft tubes in use

include the elbow hydracone and spreader types

Despite the differences found in construction and

design the draft tube must accomplish the desired objecshy

tives while offering a good hydraulic geometry to the flow

passing through it An inefficient draft tube defeats its

own purpose

Ohapter II

DISCUSSION ~ TURBINE LOSSES

A General

lhe head that 1a actually utilized by the turbine 1a

less than the effective bead as defined by equation ($) by

the amount that 1a lost due to mechanical and hydraulic

reasons

Mechanical loaaea are a function or the turbine 8p$ed

fhis ia not a lineaz- function but varies eomewhere between

N and N2 (3- Pbull 224)

Hydraulic losses encounteled in turbines ma- be subshy

divided aa to the location or occurrence (3 p 225-227) aa

fOllOW$S

(1) Penstock and scroll case

(2) Wicket gates

(3) Between wicket gates and turbine runner

(4) Runner passages

(5) Runner exit into draft tube

(6) Draft tube and

(7) At exit from the draft tube

The flow in the penstock scroll case wicket gates

runner passages and draft tube may be envisioned as

examples of flew in conventional pipes elbows and convergbull

1ng passages If this comparison may be made it could be

assumed that the losses encountered in these locations

would be proportional to vn ~ value ot N is normally2g

aesU111ed to be 2

he losses encountered between the wicket gates an4

the turbine runner and exit lossos are special cases which

will be discussed separately

B Shock toes_

The flow betwe n the wicket gat outlet and the runner

blade entrance is or particular 1nt rest because no direct

comparison vith common flow situations is obvious

Conaider the vector diagram (7 Pbull 7576) in Figure 2

The veetoo v1 is the absolute entering velocity of the

water and is fixed in magnitude and direction by the setbull

ting or the wicket gates The vector l11 1e the peripheztal

velocity of the runnel which tol any given turbine 1e

dependent only upon the turbine rotational speed The

combination of these two vectors ylelda the third vector

v1 which is the relative entering velocity ot the water

nere is only one setting ot the wicket gates for a

given turbine a peed that will produce an angle B1 which

coincides with the blade angle B1bull At other gate settings

the vector v1 will rotate and change in magnitude in such a

9

t ehion that B1 will beoome either greater or 1 sa than B1bull Th1 give rise to tbe phenomenon term d shock loasft

If B1 1a greater than B1 the relative ent ring veloebull

ityt v1 will have a compon~nt opposing the forward motion

of the runner The shock loss could be typified bullbull that

occasioned by direct impact or the water 0n the blade- If

E1 is lese than a] the vector l will overshoot the blade

and the flow will tend to eddy around the forward portion

or the blade tip

The shock loss can then be either due to impact or

eddying flow Since the area norm 1 to the radius at outlampt

of the w1eket gftee is essentially equ 1 to the area normnl

to the rad1u~ at the inlet to the turbine runner the combull

ponents ot vl and vl perpendicular to ul will b approxishy

mately equal This leads to the conclusion that xxbull ~epresenting the shock vector 1 parallel to Ulbull

For either the impact or eddy case the trigonometric

law of $1nee leads tot

XX

bull ul - sin (Bi-Al) vl eln Bi

It it 1a assumed that the energy lost in the shock 1a

the Telocity head ot the shock component XX then

10

VELOCITY VECTOR DIAGIWI

TYPES OF SHOCK LOSS

xbull X

IMPACT BDDJ

XX 1a Teloc1t7 caponent ot shock

Figure 2 - ~bine Runner Vector Diagram$ and Shock Loss Diagrams

11

2 shock loss (XX gt2g

C =sin (BimiddotAl)Let (1)sin Bi

(UlmiddotCV1)2Then shock loabull (2)- 2g

For a given gate opening C ia a constant ranging

from about 14 to 10 For a well designed wheel it is to middot

be expected that C would be approximately equal to U1V1

at rated conditions ie at point of maximum efficiency

This point will occur in the neighborhood of 3~ to 78

gate opening for moat turbines For overgate conditions

the angle A1 becomes larger so the value of C would

decrease For gate openings below rated conditions t he

angle A1 decreases and C would decrease One could expect

a fairly uniform decrease in t he value of C as the gate is

closed from t he overgate position

The velocity v1 is approximately constant for any

turbine speed since the area and rate of flow both decrease

fairly uniformly However for a given gate opening the

velocity V1 will decrease with increased turbine speed

From the foregoing comments and equation (2) the

following trends can be established

(1) For constant turbine speed the shook loss curve

will be close to parabolic in shape concave upward and

have its maximum near t he point of complete gate closure

--

12

and its minimum near the rated gate position

(2) For conatant gate opening the shook loss curve

will approximate a symmetrical parabola with its vertex

the point of minimum loas located at the rated condition

of operation (7 Pbull 79)

c Exit Loas

It can be seen from Figure 2 that the exit loss from

the turbine would be v222g if no draft tube were present

The addition of a draft tube permits the gradual reduction

of velocity by an increase in cross sectional area between

the exit of the runner and the exit from the draft tube

The exit loss and the frictional loss encountered in

the draft tube may be placed together in the expression

m va2 (3)Exit Loss ~---2g

For the ideal case of no friction in the draft tube

m is equal to the square of the ratio of the area at exit

from the runner to the area at exit from the draft tube

In an actual turbine installation however friction

will change the value of m (7 p 84-85) to somewhere

between that for the ideal case and a maximum ot 10

In the interest of maintaining a minimum exit loss

the turbine should be designed and operated so the velocity

V2 will be minimum This will occur when the discharge

13

vector is at right angles to the tangent to the runnerbull

ie the angle A2 1e ninety degree bull It ia to be expected

that this condition will be tultilled near the design con~

d1t1ons ot the ~bine

Current design praetiee 1 to have a small component

ot v2 in th$ direction of turbine rotation at rated condibull

tion$ ltS p 938)

For a constant turbine speed the d1seharg or exit

loss is ess nti lly a constant

For a constant gate opening the exit lo s curve is

aptrroximately a symmetrical pa~abola with ita vert x the

point or minimum loss located at a slightly lowe~ speed

th n the turbine rated speed (7 Pbull 79)

Chapter III

PROPOSAL OP ALlERMAlE MFTBO 0 CO TROL-A lz ~ Location 2 Control

Thua tar only practice and theoretical aspects appemiddotrbull

taining to present day turbinea have been d1acuaaed It

haa been presented that control over the ~bine ia ezerbull

oiaed b y manipulation of the wicket gatea located 11101led1bull

ately preceding the runner These gate - upon rotation

modify both the magn1tu4e and the direction ot the entering

velocit7 Moreover it has be n shown that a simultaneous

change in these two variables leads to inefficient operabull

tion by the introduction of shock loss he farther the

point of operation a from the rated conditione the more

aerioua ia the ahock loss encountered

Any attempt to better turbine pertorance at other

than rated conditione and tbne flatten the top ot the

etticieney hill8 must concentrate upon the lessening ot

the ahock loaa It 1a a aumed that 1 provement in the

scroll case gates and runners would lequ1re sueh pertecbull

tion 1n machine work and metal$ as to be prohibitively

expensive

It ie surmised that any move to elblinate eYen parbull

tially the shock loss would require separate control ovel

l$

the flow and gate exit angle Since it is improbable that

d1~ect1on could be controlled at any location other than

where the gatea are situated in current turbines it will

be assumed that guide vanes will be necessary regardlesa or the method used to control the rate of flow

The primary purpose ot th se guide vanes 1s that or control over the direction ot the incoming water They

should be free to rotate in much the same manner as ordibull

nary wicket gates in order to exercise control over th

turbine speed

If the rate ot tlov is to be controlled elsewhere it

must be modified either in the penstock or the draft tube

Devices that could be used are standard valves gates

variable orifices variable venturi sections and associated

flow regulating schemes

Alauming it were decided to locate such a device upbull

stream of the turbine it would be necessary to allow disbull

tance tor the flow picture to become reestablished prior to

entry to the turbine A contused flow making transit of

the turbine passages would only contribute additional loesbull

ea Such a distance allowance would be perbapa 20 to So

diameters (2$ Pbull 119-123) In large penstocka th1a would

repreaent a considerable distance Which from the viewbull

points ot convenience and control would be undesirable

Attempts to ascertain the effect or additional tlov

16

reduc ion at the wicket gatctsmiddot wae ade 1n the lfadraulioe middot

Laboratory of Oregon St middot te College in 1933 (20) Three

d1tterent thode ot reducins the tlow were t~ied

(l) Locking in the cloeed position pairs or wicket

gatea located opposite to eaeh o~er on the -periphery ot

the wheel

(2) Locking adjacent gates in an open position by

inserting blocks of wood between them and

()) Suocess1vely looking adjacent gates in the closed

position

The results indicated a arked reduction in both power

and efficiency when compared to the curves tor normal gate

operation However it was demonstrated that it was poae1bull

ble to ahitt the power and tfieiency curve ill relation to

turbine apeed lbis important feature will be diacussed

later

ihe main conclusion of the investigation was that conbull

trol by the conyent1onal wick t gates was auper1or to other

methode egtt control exercised at the gates the aelvebullbull

It would app$ar that the bebullt location tor flow conshy

trol would be in the draft tube since none of the objecbull

tiona prev1ously mentioned wou~d eziat there

As bas been stated previously the sole object or the

17

18

turbine is to produce power as etfic1ently as possible

The equation tor the power output of a turbine () Pbull 227)

PaWHe HP (4)55o bull bull Assuming the head 1a constant and a g te located in

the draft tube decreases bhe rate ot flow the power eu

only be increased if the etticiency increases

The ettective head Gn the turbine 1s conventionally

d r1ned as the difference between the auma ot the elevashy

tion head pressure head and velocity head at the entrance

to the turbine casing and the tailrace ($ Pbull 872)

lt ie recognized that the theoretical treatment ot

shock loss as given is highly approximate and serves only

to dictate certain trenda For example the area at xit

rom the wicket g tea CfUl be measuPed with some exactness

but there exists no guarantee that the wateP particles will

complet-ely fill the apace oz- will exit at the establiahed

g te angle The same can be said of the exit trom the

runner blades AssUIlptiona were implied which would indishy

cate that all water particles passing a given croea section

ampH traveling at the same velocity in the same direction

the e alone are autt1c1ent to show 11m1tationa in a theoretbull

1eal approach to the problem

Assume a turbine with ordinary wicket gates tor oonbull

trol compared gainst the same turbine with a gate in the

18

draft tttbe tor supplampment1ng control or the rate ot rlow

Let it also be assumed that the two turbines are opershy

ating at the same point It 1s desirable to predict relabull

tive performance of the two turbines 1 this point of

operation is such that edd7 s hook loss ot reasonable proshy

portions is present in the fir t turbine

~ tull erteot of the shock loss will be exper1 need

by- the fir t turbine

lhe second turbine will derive certain advantages 11

the gate in the draft tube is adjusted to reduce the tlov

1n the proper amount Since they vary a the square ot

the veloo1t7bull the lossabull in the aeroll case wiomiddotket gate

and runner passages will decx-ease aetet-r1ng to Figure 2 1

it can be seen that a decreased velocity v1 w-ill reduce the

eddy shock losa

The ent loss in the dJtaft tube of the second turbine

will be the sum ot the tr1ct1onal loss and the velocity

head at ex1t The velocity head dissipated will be greater

due to the closing action or the gate but the reduoed

t~ictional loss which ia a tunction ot the rate of tlow1

will partially balance this

It 1a entirely possible that the net reduction in

losses in the second turbine will lead to a greater ettibull

oiency and more power output than 4eYeloped by the first

turbine

19

In Figure 3 the plot ot power output against turbine

speed for Curv A~ represents the typical family of curvea

tor a reaction turbine Th b st sp ed is the locus ot

points connecting maximum eft1oiency at each gate opening

The operating speed is the coZUJtant turbine apeed which

passes through the point ot maximum efC1ciencr of the turbull

bine The plot of turbine efficiency against power output

for Curve A is also ahown

It the turbine with flow regulation in the dratt tube

oan demonstrate superior power and efficiency at part loads

the effect would be the same as a shifting or the power

curves toward the condition shown fop Curve B 11 Thisbull

illustrates th ultimate case of the uperpoait1on of best

and operating speeds It will be noted that the pet-form~

of the turbine ot Ourve Bu 1a better than that of CUrve

A at part loads because of ita ability to sustain a relabull

tively high etticienoy ovel a Wider range of power output

o Reguireaegts tort Test Velitication

It is desired to deterra1ne the effect on the turbine

performance b) the addition of a gate in the dratt tube

Th step in the teit will bet

(1 To determine the power output and efficiency ot

the turbine tor wicket gate settings above and below rated

conditione for a wide range ot speed

20

CURVEAbull

TURBINE SPSBD TURBID SPEKD

POIBR OOTPOl

Figure 3 - Turbine Performance Curves

21

22

(2 peat (l) with the gate installed in the drat

tube

(3) middot Converting middot all data to a constant head compare the

powere and effioiencies at the same wicket gate setting and

turbin speed tor the two cbullses

If the ddition or the gate indicates an improvement

in power output and efficiency and the powe~ curve shifts

to the right along the turbine apeed scale the advantage

ot draft tube con~ol of the flow will hav been demonshy

strated

Chapter IV

A E9J11pment

ih turbine used in this test is lJ 5 1nch Pelton

reaction turbine with a rated output ot 30 horsepower under

a head of 56 feet at a speed ot 720 reYolutiona per minute

Views of this turbine are hovn in Figures S and 6 The

turbine is installed on a concrete pad located over an open

channel in the Hydraulics Laboratory at Oregon State Colshy

lege The date of manufacture of this turbine was 1915

The water was delivered to the turbine from a sump

reservoir by two pumps operating 1n parallel Each pump 1a

an 8 inch Pelton double suction centrifugal pump witb a

rating of l$00 gallons per minute at a head ot 75 teet with

a speed ot 1175 revolutions per minute Tbe inlet tlange

ot tne turbine is $pprox1mately 18 feet above the center

line of the pump

A direct current generator was coupled to the turbine

to receive tne power d veloped as shown in Figures 4 and 7 The generator is a Spr gue Electrodynamometer rated at SS horsepower with a speed range of 7$0 to l$00 revolut1one

per minute The classification is type LO 26A 2)0 volta

Figure 5 - View of Test Turbine

Figure 6 ~ View of Test Turbine

and 149 amperes lbe generator ti ld was aepar tely

excited using direct current from a motor g n r tor ampt

(l$ p 4~8)

The power output of the generator waa dissipated in

the water rheostat (3 p 488-489) shown in Figures 9 and

10 The galvanized tank contain d water ot variable d pth

on an electrode ot cast iron m aauring 1bull x 1 x 1

In the initial installation of the turbine it was

intended that the power output should be measured with a

Prony brak bull For th purpoa68 or this teat it was decided

that the brake was too instable and the generator was

substituted The platform for raising the generator the

nee asary two teet for alignment was built out of available

material In this case heavy laminated wood blocks reiashy

torced with other timbers were used and bolted through the

concrete deck (11 Pbull 36-$7)

Due to the light concrete deck the lack ot mas in

the platform and the slight misalignment in the flexible

coupling ao e vibration waa encountered It seemed to

ncr aae linearly to a maximum at the speed of bout 750

revolutions per minute Above this speed no vibPation was

noticeable The vibration waa not se~ere and does not

appear to have materially affected the test results

26

B Intrumentat1on ~ eaeur1ng Devices

The pressure head at inlet to the turbine vaa meaave4

bymeane ot two )6 inch waterbullmeroury manometerbull connected

in series as shown in Figure 8

The terminal voltage ot the generator vas meaeured by

a laboratory voltDleter with a range to )00 yolta and callbull

brated to within 15 Yolta

The armature current bull and hence the line current was

measured by a laboratory ammeter with a range to 150 amperea

and callbrated to w1 thin o 7S amperes

Tae rate ot tlow was established by weight and time

meaeurementa The weighing ank has a capacity ot 121 000

poundsJ the weight belng indicated by Toledo direct reading

scales Timing was done with a hand atop watch with clivibull

aion ot 02 second

he ~ater level in the tailrace was dete~1ned by a

hook gauge lhie was read to the nearest 001 toot

The turbine and generator speeds were eaaured by a

hand tachometer The technique of almost cont1nuoua readbull

ings of the speed gave an error ot no more than 5 revolubull

tiona per minute

c Operational Procedure

Atter the water level in the aump was checked to

insure an adequate auppl7 the puapa were primed and

27

Figure 7 - Test Generator and Plattorm

Figure middot8- Instrument Board and Field Rheostat

28

started After venting they were valved for operation 1n

parallel

The motor generator set was started to supply the

field current and the circuit breaker was closed Water

wa added to the water rheostat to the level shown in

Figure 10 ~ field current wae minimized by cutting in

all the f ield resistance in the field rheostat of Figure 8

The l2 inch gate valve shown in Figures 5 and 6 waa

slowly opened and the turbine and generator brought up to

speed The 12 inch gat valve and turbine were vented and

the pumps were checked to insure neither had lost ita prime

lhe water rheostat offers very steady load 1f the

water level is essentially constant and the water temperabull

ture 1a fixed () p 488~89) In order to maintain this

constant temperature it was decided not to circulate the

water in the rheostat but rather to allow the water to

boil thua achieving the desired result A standing wave

was set up on the face ot the electrode by the boiling

action but a atable load was eatablished except at very

low water leYels where th11 agitation led to fluctuationa

in the line current

After putting the turbine and generator on the line

maximum power was dissipated in the rheostat by redueing

the turbine speed to between oSO and Soo revolutions per

minute Salt vas added to the rheoetat wat r to increasemiddot

29

Figure 9 - View of Water Rheostat

Figure 10 - View of Water Rheostat

Separate Field ExcitationFrom Motor-Generator set Compound Water-Mercury

---shy

re Manometer

I Q)

~ 0

~

Book Gauge

Open Channel

I

Slap Reservoir

Figure 11 - Wat~r Flow Diagram and Electrical Layout

31

waiting pe~iod ot perhaps an h~ followed

while the boiling point or the water wbulls reacbe4 During

this ti+ne the manometer was vented end eheoked electrical

measur1ng 1nstlUments were connected end the hook gauge was

adjusted tor elevation

It required about two- houtte tor the generator to reach

its normal operating tempe-ratu~e_ After the water in the

rheostat and generator had reached their operating temperabull

turea it was possible to begin the taking of data

The only vaPiable which was controlled wee the turbineshy

generator speed However the upper l1ut1t of safe line

current was slightly over 100 ampJilPampPes and the eireuit

breaker would open when the current reached lOS ~ere bull

Control was exercised by means ot regulating the water

level and salt 1n the water rheo tat and the res1stsnoe of

the tield rheost t~

The etfeet ot each type ot regulation on the three

variables is shown below

Volta Aaperebull Speed

Inc Dec Inc Dee~ Inc Dec

Wa~e1 Level Inc Dec~ X

X X X X

X

Salt Concentration

Inc Dec X

X X X X

X

field Resistance

Inc Dec

X X

X X

X X

32

Jlot all methods gave the ame amount ot change in a

given variable and a period of experiment and trial led to

the following scheme starting the rune with the lowest

turbine speed the water level was high with a high amount

ot salt and the field resistance was cut completely out

Aa it became necessary to increase the speed tor each

aucceasive run either cutting in t he field resistance

decreasing the salt concentration or lowering the Vater

level would produce the desired result However decreasbull

1ng the salt concentration had to be done Without a net

gain in water which led to a tluahing procedure that was

not particularly good because cold water was introduced

which required time to heat to the boiling point Cutting

1n additional field resistance was a good method but th1a

increased the amperage possibly to the point of opening

the circuit breaker Lowering the water level was aatiashy

factol1 until the level got too low causing the current

fluctuation previously mentioned Actually it turned out

that a combination of lowering the water level and cutting

field resistance in would carry the speed from ita minimum

to 1ts maximum value it the proper choice were made each

time the speed waa to be changed At the conclusion of

each aet of runs at a high speed the water level would be

low and the field resistance high

33

TURBINE

PAD AND DECK

TAILRACE

WATER SURFACamp

CONCRETE

DRAFT TU1B INSERTS

7 5( DRAFr TUBE

FLltJI ARIA

5~ DRAFT TUBE

FLOI ARSA

Figure 12 - Sketch of Draft Tube and Test Inserts

34

Figure 13 - View of Draft Tube Insert

Figure 14 - View of Draft Tube Insert

D c __ ~s_middot hedu_le of

A number was assigned to each run The fi~st number

applies to the draft tube tlow areas

1 bull 100~ flow area or 0~ oonatriction

2 - 7S tlow area or 2$ conatr1ct1on

3 SoC flow area or so~ constriction

The second number refers to the wicket gate openings

9 over gate opening

6 bull intermediate gate opening

4 bull one h lt gate opening

The third number 14entif1ea the location of the particular

1Wl in a set ot rona made at a given dratt tube tlow area

and wicket gate opening

fnua run number 1bull4bull10 would identity this as the

tenth run ot a set made at halt gate with 75 ot the draft

tube t1ow area

Rune w re made tor a g1yen dratt tube condition

Firat tor tull 41-aft tube flow area seta ot rune were

made for the overgate halt gate and intermediate gate

conditione An insert was placed in t he draft tube and

rune based on the same gate conditions were made tor the

7S~ draft tube flow area case The insert was then changed

to allow only $~ draft tube flow area

The inserts are sketched 1n Figure 12 and photographed

ln Flgurea 13 and 14 They oonaisted of circula~ segments

36

or l2 ineh plywood mount 4 on wooden legs 10 inches high

The 1nse7te were placed in position and secured by th use

ot a-clamps on the legs and the outside ot the bottom of

the draft tube The obvious disadvantage to this method

waa the neoeasity tor draining the water from the tailrace

tor a change ot 1naert The advantage vas of course the

simplicity ot design and construction

Chapter V

DATA-A Original Data

The normal data-taking crew consisted or two men

Assuming adjustments having been made to secure a certain

turbine speed (aee section on Operational Procedure) one

man would take semi-continuous speed readings with the hand

tachometer until a state or rotational equilibrium was

reached This could be only a period or two minutes up to

ten or tifteen minutes As soon as steady speed was

assured the data taking would begin The second man went

to the weighing tank Where a minimum ot three weighingamp

were made The requirement was to get three consecutive

readings such that the ditterence between tbe smallest and

largest time did not exceed 04 seconds The time to

collect a given weight ot water was then assumed to be the

arithmetic average of the three times He then went to the

hook gauge determined the hook elevation and then

recorded the data on the data sheets The first man meanshy

while had taken readings of the line voltage line current

and manometers and checked the turbine speed by multiple

readings During the length of the run all values were

38

checked to determine mean values for recording

The minimum length of one run was about five minutes

If one or more measure ants tended to drift during the run

all values wer discarded and a new run began as soon aa

qu111br1um was stabl1shedo

B -0-al_e_u_l_a_t--d Data

The h d on the tu~bine 1 defined by

($)

The maxtmwm velocity V4 was equal to about o8 tampet per

secon4 which makes it a negligible quantity when converted

into velocity head

An engineerbulla level was used to deterine the d1ffePshy

ence 1n elevation between the compound water-mercury manoshy

meter and the hook gauge Using this value the equation

for turbine bead becomes

where z4 is the hook gauge reading

The rate of flow 1 cent

w weight or water collected average time to collect

The inlet velocity v1 vas calculated by dividing the

weight rate or flow by the specific weight of water and the

)9

area ot ~e inlet pipe This was equivalent to dividing

the weight rate of flow by 490 Then the power input to the turbine is equal to

WHpin rri

10 (6)

Also

(P ~ut) Turbine

(P out) + Generator

(P lost) Generator

The power output of the generator is simplJ the

produot ot the terminal voltage and the armature (line)

curPent The power lost in the generator can be subdivided

into copper losses and stray power losses lo evaluate

these cunes based on losses of an identical generator

11leampsured by the Department ot Mechanical Engineering were

used The loss curves are reppoduced in part in Figures

15 and 16

Determination ot generator losses proceeds as tollowau

(1) From Figure 15 detem1ne the vo1tage drop in the

armature circuit using the temperatures of 1220 F and the

meaaured current

(2) The induced voltage is t~e sum of the terminal

voltage and the voltage drop 1n the armature circuit

() Entering the induced voltage and the turbine speed

into Figure 16 the stray power loss can be determined

(4) The copper lose can be evaluated from Figure 1$

using the measured current and the temperatlll-e of 1220 P

40

25 ~------~--------~--------~------~

U) -U) - 20

f-4 ~

-~ -gt 0

0

VOLTAGE DROP

~ - i -

- bullbullbull bull - -middot-middot -+ ~- + -t--+ ~ - ~ middotbull ~-~ middott- -+----- _ -4 middotmiddot- --~-+-t---r~~ ~--+t-t- - ---t-c-++~-ulf--

0 50 75 100

Figure 15 - Curves of Generator Voltage Drop and Copper Loss

41

1200

1000

800

600

800

0

0

~-

middot--~ 1shy --1 + bull l

100

I -

150 200

IIDOOED VOLTAGB (VOLTS)

Figure 16 - Curves of Generator Stray Power Loss

_ j

-bullshy -L---- shy middot -shy

250

- r

42

(5) The generator los os equal the sum of the eopp r

loss and stray power loss

~e efficiency or the turbine is taken as

etticiency u e =P out (8)Pin

~ample pound Determ1n1gg turbine Power Output

The following data are taken trom that ot Run 1-9-1

Line voltage 1040 volts Line current 870 amperesSpeed 355 revolutions per minute

The induced voltage 1a determined as follows

Line voltage 1040

Voltage drop 90 using Figure 15 with line current of 870 amperes and temperature ot 122 degrees)

Induced Toltage 1130 volta

The power output of the turbine is determined as follows

Generator output 90$0 (line voltage z line current)

Oopper loss 7 (using Figure 15 with line current of 870 amperes and temperatUe or 122 degrees)

Stray power lose 470 (using Figure 16 with speed ot 355 revolutions per miDUte and induced voltage or 1130 volts)

Turbine power output 9527 vatta

or turbine power output 1s 12z2 horsepower

43

The conversion of the calculated data to a constant

head is based on the conventional assumption of constant

efficiency regardless of turbine head For a constant head

ot 81 teet a purely arbitrary figure the tollowing relashy

tionships are ass1lJiled to be true

I ____L (9) (i)l72

(10)

For these two values the specific a peed may be combull

putedt

N t Jt VPt (11)8 243

Chapter VI

~RESULTS

A -Pr_e_ae_n_t_a_t_t_o~n g Reaultbull

Graphical presentation ot the results ot this te1t

are given as follows

Figure 17 -Turbine characteristics with 100~ dratt

tuba 1low area

Figure 18 - Turbine characteristics with 7S dratt

tube tlow area

Figure 19 bull Comparison ot power and etticiency at

over gate conditions between 100 and

75~ draft tube flow area

Figure 20 bull COZQparison of power and ettic1ency at

halt gate conditions between 100~ and

7S~ draft tube flow area

Figure 21 bull Comparison of power and etticiency at

over gate condition between 100~ and

So dratt tube tlow area

Figure 22 - Comparison in variation ot apec1t1c

speed between 100 and 75~ dratt tube

tlow area

50

45

20

-bull - 1--shy40

bull J-~ 30

~ ex

~ 20

~~ ~ -)q

I

~ - _

- -

10~ OF DRAFT TUBE FL(Jif AREA

CONSTANT HEAD OF 8l FEST10

POIER OUTPUT EFFICIENCY SPECIFIC SPEED

0 ~--------------_--------~------~------~ 400 600 800 1000 1200 1400

TURBINE SPEED (RPM)

Figure 17 - Turbine Char~cteristics with 100 Draft Tube Flow Area

50

46

-bulllle

~ 7 ~ OF DRAFt TUBE FLOW AREA

0 -~~-rl C05STAMT BEAD OF 81 mET 1J~

POIER OOTPUT ---+- ---o ~_H EFFICIDCY ~ I shy

bull ql SPECIFIC SPEKD - ~ -

bull ~ J 10 L rmiddotr- r- -

bullz- I

~~ 30 ~~--~----~~-

20 ~ ~ middot-shy

26

~~ 25

~0 ~r-----i (

Tbull -bullshy

400 600 800 1000 1200 1400

TURBINE SPEED (R PK )

Figure 18 -Turbine Characteristics with 75 Draft Tube Flow Area

47

EFFICIENCY 60

1-----shy

-~ 50~--~--~~-~middot middot middot middot r~-~----~~~~---4~-r~-~~gtt

II

POWER~ J ~ bull bull

u I

sH

40~------+-------+---- -~~--~~-~~~~

~----~rl 1 bull

I

I

0~--------------~------_------~--------

~ -OVER GATE CONDITION

COIJSTANT HEAD OF 81 FEET

0 o 10~ DRAFt TUBE

_-- _ 7~ DRAFT TUBamp FLON AREA II

10_~-----+--------r-------r----~~

400 600 800 1000 1200 1400

TURBINE SPEED (RPM)

Figure 19 middot - Comparison between 75 and 100 Draft Tube Flow Areas of Power and Efficiency at Over Gate Conshydition

48

t

bull --4 r ~- ~ middot~

70 1-----------+-~~~~~+middot ~ ~~ middot middot -~~--~~--------~~----~-+1

-~-

Atbull bull

lla-

60

amp0

40

20

10

oampOO

t _ - - ~-+- - -~-

l2 GATB COJIDITIOJJ

COJISTABT HJW) OF 81 JBET

o 0 lOQ( DRAFl TUB8 FLOI AREA

e-- - e 75 DRAFT TUBE FLOW AREA

800 1000

- r-

~

TURBIbull SPBIID (RPII)

Figure 20 - Comparison between 75 and 100 Draft Tube Flow Areas of Power and Efficiency at Half Gate Conshydition

49

60

50

-40

bull 30

IIQbull

20

10

0

400

- t - ~

EFFICIENCY

_J bull - bull bull

~ r r middot t -+ shy L -t -

OVER GAD COliDITIOI

CONSTABT BEAD OF 8l FBB

o o 10~ DRAFt TUBE FLOI ADA middot--- 5~ DRAF TUBE FLQPi AREA

600 800 1000 1200

Figure 21 -Comparison between 50~ and 100~ Draft Tube Flow Areas of Power and Efficiency at Ove~ Gate Conshydition

50

25

20

15

10

0

Figure 22

~- T -4 -t- -l --~-

t-~ I

middot --~- t ~---- _ __ _ + --

----~- --r-- --

~-=J-~-=-~ -==~ _ ~- -- ---f---1 - shy

CONSTANT HEAD OF 81 FEBT

o--o 1~ DRAFT TUBE FLltll AREA

75C DRMT TUBK FLCIJ AREAmiddot--middot-middot 600 800 1000

TURBINE SPEED (RPK)

Comparison of Specific Speeds for 75 and 100 Draft Tube Flow Areas

51

B Discussion 2 Result

Consideration of Figures 17 and 18 indicates the

overall eftioi ncy pattern or hill is significantly or

rounded for the 7$~ flow area than for the 100~ flow area

bia implies a greateP efficiency is possible at speeds

leas than or greater than design speed with an insert in

the draft tube However the muilDum efficiency is lemiddotas

Direct comparison at over gate conditions is made in

Figure 19 ~e same general trend is noted tor both the

etticiency and power curves for the 7$~ flow area case

The eurves show higher values at overspeed than do the

correaponding cWvea for the 100 flow area case It ia

not clear whether the curves have been shifted by the dratt

tube constriction or whether the curves simply bulge past

the normal curves at both overspeed and underspeed condishy

tions The power curves apparently peak near the aeme

point bullalthough maximum power is still obtained with the

normal draft tube area

For the comparison at halt gate operation shown in

Figure 20 a general improvement has apparently been made

by restriction of the draft tube flow area At every speed

the etticienoy and the power is greater for the restricted

tlow case The two ett1o1ency curves and two power curvea

are practically parallel throughout the speed range ot

teat

As the flou aroa i e decreased still farther a s1gn1

ticant change appears Reterr1ng to Figllle 211 tor the $0

flow area curves it a obvious that exit losses have

become excessive at the overgate condition because the

efficiency and power are everywhere leas than tor the case

of normal draf t tube area

Earlier it was pointed out t hat 1t the r esult s 1nd1bull

eated an increase in both power and ef tieiency- t hen it

could be assumed tha t the additional los s i ntroduced with

the draft tube insert is less than the diminished losses

due to leas shock losa and water passage losses For the

places where both the efficiency and power have been

increased we can assume that the insert has improved turshy

bine performance

For the places where the power haa been decreased

nothing can be said as to the elimination of ampbock loss

because the new lose present with the drat tube insert has

overshadowed any gains in eftecti Ve head upatJ-eam of the

insert

Near the peak of the efficiency hill howeve~ it may

be pointed out t hat shock loaa ie a minimum with a normal

draft tube and the insert merely adds an additional loss

with the resultant decrease in maximum efficiency tor the

7$~ flow area case

Perhaps the most s1gn1ticant set of eurves is shown aa

53

Figure 22 In this graph values of specific speed tor the

75 and 100~ flow area cases for both over gate and one

halt gate openings are plotted against turbine speed At

every speed and both gate openings the value ot specific

speed for th 75~ flow area case is greater than that for

the 100 t1ow area ease

Since the head is a constant for both situations this

may be interpreted in either of two ways trom equation

(11)

(1) For the same turbine apeed restriction of the

draft tube t1ow area resulted in greater turbine power

(2) For the same power amputput the turbine with 75~

draft tube flow area operated at a greater speed than did

the one with 100 flow area

Since the required diameter of a turbine varies

inversely with the speed the second interpretation could

be stated such that a smaller turbine could be used to

develop the same power output

Whether viewed trom the aspect of increased power

greater speed or reduced size the performance of the turshy

bine with reduced draft tube flow area is superior to that

with the nolmal flow are in the draft tube

The curve of specmiddotific speed versus turbine speed for

the so draft tube flow area case at over gate cond1t1ona

was not included in Figure 22 This curve lies below that

for the 100~ flow area c se at all speeds

In elaboration ot the second interpretation of Figure

22 attention is directed to the relative magnitudes ot

increased apee1f1c speed tor the two gate openings Assumbull

ing that the increase in specific speed implies a shift ot

the power curve to the right along the turbine speed scale

the power curve would be shifted more tor tbe halt gate

opening than tor the over gate opening

It thia trend could be extrapolated to the other gate

openings the tendency can be seen tor the line ot beat

speed to rotate toward the line of the operating speed as

illustrated in FigtU-e ) The advantage of this has already

been discussed

This particular turbine has a low specific speed tor a

reaction turbine Aa the rated value of apecitic apeed tor

reaction turbines increases the line ot beat speed departs

even more radically from the line of operating bullpeed It a

test similar to this were conducted on a reaction turbine

ot gleater specific speed it is pJobable t hat the rotation

ot the line of beat apeed would become more p~onounced

The scheme used in th1a teat had two obvious dr wbull

backs The first was the decision to leave all the wicket

gamiddottes installed tor all conditions ot the draft tube

These gates predominated in control of the tlow The

inserts added to the draft tube merely acted as auxiliary

55

contrGla

The aecond drawback was the choice or device to place

in the draft tube The reasons foll selection of this type

of device have been previously mentioned It is to be

anticipated that adaptation ot dratt tube flow control

would result 1n a better device for an actual turbine

installation Such apparatus might take the form of a

pneumatic bladder or a h7drau11oally operated variable

venturi section in the draft tube It is conceivable that

the gate as used in this test might be adapted also

Chapter VII

OONCLtJSIOfS

From the results of this test the following eonolubull

e1ona aa to the effect ot a variable draft tube flow area

on the performance or a r action turbine may be drawn

(1) The effect ot a variable draft tube tlow area 1a

generally favorable upon the operat1Gn ot a reaction turbull

bine because or the tendency tor the line or beat speed to

rotate toward the line ot operation This resulte in

better performance of the turbine at partbullloads

(2) he etf1o1ency eh111 tor the turbine beeomaa JDore

tlat at the top leading to a smaller max1JilWD effic1enc7

but e reater etticieney at other pointe of operation with

the insertion ot an auxiliary control ror the rate ot tlov

in the draft tube

(3) The power output of the turbine will increase at

over speed over gate conditione as well a at part gate

conditions with the proper amount or draft tube eonatr1cbull

tion or flow

(4) It is possible to eliminate at least partially

eddy type shock loss by tho introduction ot flow control

in the draft tube

BIBLIOGRAPBl

1 Addison Herbert A treatise on applied h-draul1cs New York Wiley 1954 724 Pbull

2 Allen o M and I A Winter middot Co111parative testa on experimental draft tubes Tranaact1ons ot the American ociety ot Civil Engineers 87t893bull970 1924

3 Barrows a E Water power engineering 3d ed ew York McGraw-Bill 1943 791 Pbull

Bovet G A Modern trenda in hydraulic turbine design4middot in Europe Tranaactions of the American Society ot Mechanical Engineera 75975bull993 1953bull

s Oreager William P and Joel D Justin Hydroelectrichandbook 2d ed New York Wiley 19$0 1151 Pbull

6 Daily Jamea w Hydraulic machinery Int Hunter Rouses Engineering hydraulics Hew York Wiley 19$0 p 8$8bull99

Daughertybull Robert L Bydraulie turbines ew Yorkbull7middot MoGrav-Hlll 1920 281 Pbull

8 Daugherty Robert L Inveat1gat1on of tne performance ot a reaction turbine ~anaactiona or the American Society ot Civil Engineers 7811270bull1304 1915

9 Davie L M Model and prototype testa Int Trend in hydraulle turbine practice symposium lranaactions ot the American Society ot Civil Engineers 1o63S3middot368 1941

lfJ Doland James J Hydro power engineering Hew Yorkbull Ronald 1954 209 Pbull

11 Gandy Theodore s and Elmer c Schacht Direct curshyrent motor and generator troubles operation and repair New York McGraw-Bill 1911 293 Pbull

12 Gibaon Arnold H Hydraulics and ita applications5th ed London Constable 1952 813 Pbull

58

13 Button s P Component loases in Kaplan turbinebull and The prediction of efficiency from model tests Probull coedings of the Institution or Mechanical Engineers168743-762 1954

14 Knapp R T~ Oavit t1on mechanics and its relation to the d sign or hydraulic equip ent Proceedings or tne Institution ot Mechanical Engineers 166150bull16) 1952

15 Langsdorf Alexander s Principles of direct curHnt mach1nee 5th ed New York r~cGrawbullH1ll 1940 746 Pbull

16 Lsrner Chester w Characteristica of modern hydraubull lie turbines Trans e~ions of the ~~erican Society ot Civil Engineers 66306-386 1910

17 Linsley Ray K Jr and Jobulleph B Franzin1 Eleshyments of hydraulic enginebullring New York McGrawshyBill 19$5 $82 Pbull

18 Mead Daniel w Hydraulic machinery llev York McGraw-Hill 1933 396 Pbull

19 ead Daniel w Water power engineering New York McGrawbullRill 191S 843 Pbull

20 Mockmore Charles A Part gate operation at water turbines Corvallis Oregon State College Department ot Civil Engineering 1933 11 numb leaves (Unpubshylshed typescript)

21 Mockmore Oharles A Flow characteristics in elbow dratt tubes Transactions of the Amez-ican Society ot Civil Engineers 103402middot464bull 1938

22 Moody L F Hydraulic machinery In c v Davis Handbook ot applied hydraulics New York McGrawshyHlll 1942 1082 Pbull

2) Ptau At-nold Hydrbullulie turbine handbook ld ed Milwaukee AllisbullOhalmers ManufactUIing Company 1948 70 Pbull

RheingalUI w J Recent developments in Francis turshybines Mechanical Engineering 74189-196 1952

25 Russell George E Hydraulica 5th ed New York Henry Holt 1942 466 Pbull

26 Safford A and E P- Hamilton American mixed tlow turbine and ita setting Tranampactions or the Amerieal Society of Civil Engineers 851237bull1)56 1922

27 bull Spannhake W1lhe1Dh Problems or modern pump and tur b1ne design Transactions of the American Society of Mechanical Engineers 56e22$-248 1934bull

28 Sutherlandraquo R A Better ethod or representing and middot tudying water turbine performance ~ansaetions ot thmiddote American Society of Mechanical Engineers 68t675bull 686 1946

29 Teats ot five models or draft tubes tor turbines Engineering News-Record Pbull 182-184 Aug 2 1923

30 White w M American hydztaulic turbines Mechanical Engineering S2t390bull39S 1930bull

31 White w M lhe hydraucGne rega1ner1 its developmentand appl1eat1ons 1n hydroelectric plants Meohanlobulll Engineering 43t37Sbull380 1921 middot

32 Winter I A Economic principlebull in designbull Int Trend in hydraulic urbin practice bull a ampoeiumTranaaot1ona ot the American Society ot Civil Engineerslo6332bull3S2 1941

33 Wiel1cenua G F Fluid mechan1ca or turbo-machineryNev York McGraw-Hill 1947 613 Pbull

APPENDICES

c

Appendix A

NOATIOB

A Angle between the absolute velocity vector and the tangent to the rwmer Subscripts 1 and 2 refel to entrance and exit ot the runner blade

B Angle between the relative 1elooity vector and the tangent to the rwmer Subscripta 1 and 2 refer to entrance and ezit or the runner blade

Angle between the tangent to the runner blade tip and the tangent to the runnel- Subscripts 1 and 2 reter to entrance and exit of the rt1rmer bladebull

Blade angle-gate opening conetant defined by equation (1)

e 09erall efficiency

g Gravitational acceleration assumed constant at 322 teet per second per second bull

H Turbine head detined by equation ($)

m Exit loss coeft1e1ent

Turbine speed expressed in revolutions per minute

Turbine speed under a constant head of 81 teet

specitic apeed of the turbine under a constant head ot 81 teet

p Power output in horsepower ot the tvbine

Power output of the turbine Ulder a constant head ot Sl teet

Pl- Pressure head at entrance to the tUlb1new

l1 Peripheral velocity ot the runneP Subacr1pta 1 and 2 refer to entrance and exit ot the JUnllampr blade

62

v Relative velocity reaulting trom the combination ot the absolute water velocity V and the runner periphshyeral velocity u Subscripts 1 and 2 refer to entrance and exit ot the runner blade

v] Relative velocity vector necessary to produce a tanbull gential entry into the runner blades

V Absolute water velocity Subscripts l and 2 refer to entrano and exit ot the runner blade

v2 Velocity head Subscripts 1 and 4 reter to the ~8 entrance to the turbine and the tail~ace wate~

w Unit weight ot water assumed constant at 624 pounda per cubic toot

V Weight rate ot flow in pounds per aeooncl

XX Velocity component ot ahook See Figule 2

Z Elevation head Subscripts 1 and 4 reter to entrance to the turbine and the taibace water surfacebull

Appendix B ORIGINAL DATA-Run

lfwnber

0-4-1 0-4-2 0-4-3 o-4-4 o-4-S o-4-6 0-4-7 0-4-8 0-4-9o-4-lo o-4-11 o-4-12 0-4-13

o-6-1 o-6-2 06-3 o-6-4o-6middotS o-6-6 o-6-7 o-6-8 0-6-9 o--6-lo o-6-11

Speed

rmiddot2middotbullmiddot(1)

336 38$ 451 S$9 620 669 6lt)$ 120 787 860 932

102imiddot109 bull

352 355 443middot 543middot 620 654AJs32

911 1001 1111

~essure Head rt (2)

410 410 416 426 431 43-7 439 44-9 452 467 482 soo $1 bull $

350 351 35middot7 )66 37-9 37-9 392 41 bull 3 43middot3 460 489

Elevation Bead

fjj $7 $7 $7 $7 $7 $7 51 57 5-15858 $8 58 56 56 $6565656 51 575As5a

Velocit Head

flj 07 07 07 06 06 06 06 os 05 os0404 03

09 09 oa o8 o8 os 07 07 06 o~o

Total Head rt ($)

47middot4 4A44 o 489 49-4 soo $02 $11 $14 $29 5imiddot45 2 576

41 bull $ 416 421 430 44middot3 44middot3 456 47-7 496 523551

Plow

lbtjec

326 324middot317 311 306 30029middot28 middotmiddot middot 386 275middot260 240 218

359 36~35 bull 349 345middot 339 330 318 300 273 240

Line Potential

vyqjbull 1060 1220 ~-0o 1920 2150 2000 2$60 2000 1940 18)015io11 o

1000 1100 139bull5 1760 1925 16$0 1620 1610 1540 1330 870

Line Current

amlscs 960 900 830 740 730655 70bull 0 530 660 600 5imiddot54 6 )60

982 930 860 780 ~3-545

79-5 74-5 670 560 370

P

Appendix B ORIGINAL DATA (Continued)

Run Number

Speed

Pbulltmiddotbullmiddot )

leasure Head ft(2

Elevation Head tt(J)

Velocity He-dfmiddotj

Total Bead tt($

Flow

lbstsec( )

Line Potential vo~ta( )

Line Current

amjs (sect

0bulllt)-1 0-9-2

3ll6 398

28o ~~1

$6 56

1o 10

346 347

390 365

1ooo 1190

aao 835

0-9-3 0-9-4 o-9-S

472 565 632

292 305 312

$6 s6 56

10 o9 o9

)$8 J7~o 37~7

381376 37o

1)6614oo 141o

820 ass ass o-9-6 0-9-7 0-9-8 o-9-9 0middot9-10

680 120 762 844 920

)24337346 366 390

56 $6 56 57 $7

09 os o8 oa 07

)89401 410 431454

367~ 357348 34o 322

1400 1J6o l36o 1310 1170

843 820 7957So 67~0

0-9-ll 0-912

1001 1100

41 bull 7 45-3

s 7 6~0

06 os 480 $18

299 268

980 65$

560 36~5

1-4-1 1-4-21-4-l1-4shy1-4-5 1-4-6 l-4-7 1 4-8 1-4-9 1-4-10 1middot4-ll 1-4bull12

354middot452 562 62q 674shy102 752 760- 863 932

1022 1100-

)82389 4014oa 416 41--7 423 428 44-2 45-7 486 49-2

51S757 51 5-7 5middot15zs sa $8 58 59

07 07 06 06 06 06 06 os o bull o 04 o J

446 45-)46middot4 471 ti7-9480 q86 491505 $19 548 55-4

)28 320 311 306 300 295 291 286 269 2582iimiddot21 bull

1080 14Lo 1550 153-5 1470 141-0 1385 1310 1310 1230 1120 855

970855 875 91-0 94~0 975 966 995 860 77-S 610 4fo

0 ~

Appendix B ORIGINAL DATA (Contirmed)-Run Speed Pressure Elevation Velocity Total Flow Line Line

Number Head Head Head had Potential Current rtjjmbull t~ bttec vyfs am~a12) ( ) ti fli 8

1-6-l $6 33$ $6 0bull9 400 364 1100 93 0 1-6-2 41 34laquo2 $6 oa 406 JS7middot iios a5s l-6-3 500 3~0 5bull6 os 356 1 1 o aos 41middot~1-6~4 35bull4 5-6 oa 41middot 352 16~0 82 0 5~1-6-5 5 bull 36_2 Sbull6 08 42bull6 349middot 161 ~ 0 86~0 1-6-6 622 366 $6 oe 43bull0 345middot 158 0 88~$ 16-A 649bull 37bull1 56 os 43-S 342middot 1570 895 1~- 386 57 07 46-0 192 ) 125A44 333middot 1-6-9 3) 404 5middot1 07 468 317 1620 675 1610 911 42-4 5-7 o6 48-7 298 168 0 61 0 1-6-11 999 451 56 os Sl ll 276 ~2-0 530 1-612 1115 485 58 04 54middot7 238 90 )3 0

1middot9-l 355 279 56 10 )45 385 1040 870 1-9-2 399 28J $6 10 )49 38$ 1140 86 5 l-9-3 ~ ao 291 56 ~0 35middot1 J8J_ JJ6o 815 1bull9-4 579 303 56 09 )68 375middot J4JO 830 l-9bullS 40- 313 )6 09 31middot8 370- 1460 82~0 1-9bull6 679 2) 56 09 3 bull8 364middot 1670 710 l-9-7 682 319 56 o9 384 ) 62 1460 79 5 l-9-8 724 33middot5 56 o8 399 3$6 bull 1480 76 -5 1-9-9 762 34middot3 $6 0 bull 8 407 )48 14910 13middotS 1-9-10 833middot )60 5middot7 os 42$ 339 144$ 686 1-9-ll 926 39middot1 5-7 07 455 318 1290 600 1-9-12 1000 41middot3 0-6 476 298 1115 510$ ~ 1middot9-13 1105 452 s o4 $14 2$6 710 )10

~

Appendix Bt ORIGDIAL J (Continued)

Run Speed Pressure Elevation Velocity Total Plow Line Line Number Head ltead Head jlamp$d P()ten~ibulll Current

r~~~m ft ft lbs~seo voltattj rgj twimiddot t 1 t2gt lt3 ou t ( rt

2-9-1 384 289 S 6 10 35 5 1400 1170 810 2-9-2 443middot 29$ $6 ltimiddot9 360 379middot 11(0 87$ 2-9-J 536 30bull 3 sc 09 )68 374middot 1)40 84 bull) 2-9-4 571 306 $6 09 3~1 372 120bull 0 955 2-9-5 623 316 S6 09 J l )6S UJSo 77$ 2bull9-6 669 327 S6 09 )92 )61 1240 905 2-9bull7 712 )39 56 os 40-3 351 12(0 86 bull0 2-9-8 ~5$~ J48 56 oa 412 348 1290 81 bull ) 2-9-9 04 )63 56 oa 42-7 339 12ltJO 76$ 2middotmiddot9-10 8$2 376 5middot1 07 440 33~- ~ o 710 2-9-11 955 394 5-1 o6 457 300 1100 506 2middot9-12 1000 421 $7 06 48middoti 295 1020 $18 2-9bull13 110~ 463 56 05 $2 267 620 3~0

oshy0

Appendix Gt CALCULATED DAgA

Turbine Run Generator Generator Turbine Turbine Efficiency Turbine Turbine Specit1c

Number OutputKWlt21

Loa~Jes KWlol

Outut K bull (H)

Input RP 12)

middot Percentlt13gt

Speed r~Jmiddot(

0ltput HP ~1

Speed r-m

( 6) middot

o-4-1 0middot4-2 0-4-3 0-4-4 0-4-5 0-4-6 O-qmiddot7o-4-8o-4-9 0-4bull10 0-4-11 o-4-12

1018 1o9a 1220 1)62J40214oa1J4oo 1357 1320 1164 997 718

046 o59 071 092 096 1071oo 134 104 100 109 107

14261sso 17)01948 2008 20322011 1999 19 09 1708 14-84 11o6

281279 27-7 276 215 273271 268 268 26h 258 24-5

soa 555 62$ 705 7)1145 742 74-6714645 51s 45-1

440 sos 585 720 195 sso sao 9$$ 985

1065 1135middot 1230

318 357 319 416 422 419412 39middot9 378 324 260 191

102 12bull4 148 191 21bull 3 22o 233 249 24924middot9 238 221

0-4middot13 418 104 699 228 306 1300 117 18)

o-6-1 982 045 1376 271 $08 496 376 124 o-6-2 o-6-3 G-6-4o-6-5 0-6-6

1023 1200 13 73 J415 139h

051 0middot66 oaa ()bull 96 088

14-39 1696 1958 2026 1986

276 27middot4 273 278 274

$20 61 8 717 7)0726

q95615745 8)5685

390 ll5middot3 sos soo 490

127 170 218 243 2$$

o-6-7 o-6-8 o-6-9o-6-lo

1288 1199 1032 7-45

o9o 094 09$ 096

1846 1733 1511 1128

274 276 271 260

67S 629559 43middot4

980 1085 1165 1245shy

436 )83316 21bull 7

266 276 270 239

0-6-11 322 1oo 566 2141 2JS 1350 101 177 0 --4

Appendix C CALCULATED DAlA ( Continued)-Run

Number Generator Generator

Out2ut Losaes xw LW- 12gt (lO)

Turbine Out2ut

ltPlJ

Turbine Inat lfP Jig)

Etpound1e1ency

PireentDl

Turbine Sed x-~m( 1

Turbine OutEut RPJl)

Turbine Specific

SeeedrIbullntbull

( 6)

o-9middot1 0-9-2 0-9-3 o-lt)-4 09-$ 0bull9-6 0-9-7 0-9-8 0-9-9 0-9-10 o-9-11 0-9-12

aao 994

111$ 1197 1206 1180 11)21081 982 784 5-49 2)9

0middot45oss o6$ 070 07$ 0-77 (l77 or~ o s06o 8 096

123~ 1402 1$80 1698 17bulllS 168$ 16bull18 ~middot5430 1151 a~J4 9

24middotgt24middot3248 25~25 260 260 259 267 266 26middot1 2S2

sos 577 63-7 671 676 650 621 60036J4

327 178

$) 610AlO 3$

92S 980

102$ 1070 1157middot 1230 1300 137Smiddot

44middot4 soo 523 ssomiddot 540so6 46-5 432 368 274 18~8

J46 176 21-1 255 2802s_A 28 289 288 265 231 168

1-4-1 1-4middot2 1-4-3 1-4-4 1-4-5 1-4-6 1-4-7 1-J-8 1-4~9 1-4-10 1-4-11 1-4-12

10bull48 1231 13-S6 1397 1)821375 1))8 1303 1127 953 683) 51

048 067 o7A07 0 bull79 oa1 oss o bullao osa 0lt)0 096 099

J468 1740 1921 1978 1958 19$1 1911 lSSi162 1)98 1045

603

266 264 262 262 261 2512$7 2$6 24middot7 24-3 233 217

551 660 13middot3155 75-6 7~-97 middot4 72$ 67 51middotJ 44middot9 21middot1

475 605 A4220

875middot 910 970_

1000 1090bull 1166 1243 1330

5816

44middot444middot5 430 427 412 392 329 273 188 l0-7

117 101 204 22$ 2)7245 2562sa 257251 222 179

a-C))

Appendix Ct CALCULATED -DATA ( Ocntinued)

1-6middot1 1023 o$2 14-41 26S 505 41~6 26~

54middot5 13middot3l-6-2 1201 067 1boo 625 47-9 17shy~middot41-6bull3 1296 oA9 1 middot43 26 9 700 so5 20bull 4 l-6-4 l3j5 o 0 19~09 268 71bull3 A5o 514 222 1-6-5 1) 5 o81 19(gt4 271 725 51-5 238 l-66 1398 081 198) 27-0 736 8 S13 252~-middot l-6j 1405 083 199i 211 733 885 $middot06 2$9 l-6 13middot9~ 103 2amp 0 279 71 8 985~ 467 ~-69 1228 1 bull 02 17-SS 270 661 109$ 407 ~3~ l-6bull10 1025 100 lSll 26i 573 1175middot 27~S32middot~l-ampu 153 1-00 llft3 26 444 1270 22 24bull8 1bull6-12 294 100 52a 231 22 3 1360 95 172

1-9bull1 904 048 1275 2J4Z $28 S4$ 459 1$2 1-92 98$ oss 13-92 24middot4 57-0 6JO 49bull1 176 1-9middot3 1110 066 1$76 24middot9 63middot4 I2o 536 21-7 l--9-4 1187 072 1685 251 66$ 5 $$ bull 0 261 1middot9-5 llltJ7 1710 25middot4 67-3 93$ 536 28~20-671middot9-6 1186 o 8 1708 25-7 67) 980 $15 2691-9- 1161 oBo 1660 2$middot3 6$6 990 508 29-1 l~- ll-32 oB) 16sect0 2$8 632 1030 471 291 1-9bull9 109$ oa5 2$7 614 1075 29S~middot 0 4imiddot41-9-10 9~91 oas 262 S$1 1150~ 3 o 292 1-9-11 o9o u57 12JiO 21gt 26-77middot74

-45 26sect ~middot91-912 $69 091 sas 25 middot3 1)0$ 196 2J-8 1-9-1) 220 098 426 2)9 178 1390middot 84 16 6

0 0

Appendx C CALCULATED DATA (Continued)

Turbine Run Generator Generator lurbine Turbine Eft1e1eney Turbine lurbine Spee1f1c

Number Output Losses Outit Input Speed Output SPed middot k_-V KW R _ H_bull_P Percent r Thm HP rpm_ (9) tlo) 11) middot (12 _) (lJI ( ) (1$ (14)

2-9-1 9--46 055 1)62 258 528 580 164 2-9-2 1024 056 248 58 4 665 4 9 191iimiddot48 4~middot0 2-9-3 1132 067 05 2$0 641 795 52q 237 2-9-4 1148 065 1027 2$1 -~8 845 525 252 2-9-5 11 77 oso 16-83 253 6 910~ 522 270 2-9 6 1122 071 1600 251 622 960 47-5 2722-9-A 1092 015 1562 257 608 1010 445 2z12bull9- 1052 079 1514 261 580 1060 41middot7 2 2 2middot9-9 986 o82 ]429 26) 542 1105 372 277 2-9-10 915 086 1340 268 500 1160 334 27-6 2-9-11 638 087 972 254 )81 1270~ 229 250 2-9-12 )28 090 828 259 )19 1295 179 226 2-9-13 192 094 383 2$ 6 150 1370 7 3 152

-3 0

Page 8: The Effect of A Variable Draft Tube Flow Area on the

I

bull

filE EPPEOI OF A VARIABLE DRAFT TUBE FLOW AREA

ON THE PERFORMANltJE OF A REAOTIO TURBINE

Chapter l

IITRODUClIOH

A hrpose and Scope of Invst1pt1on

Present day control of reaction turbines is accombull

pl1ahed by the use of wicket gates immediately- preceding

the turbine runner These gates otter an interrelated conbull

- trol to the quantity and direction ot the water entering

t-he runner ie a change in the amount ot flow will rebull

middot ult in a change in direction This combined control leada

to loesee at all but the rated or design condition ot the

turbine (2$ Pbull )71)

This investigation dealt with an att mpt to better

turbine performance at all points of operation b y the

eatabliahment of separate controls over the rate of flow

and the d1J~ect1on ot the entering watebullbull

The only physical modification of the test tlutbine

was the insertion of flow restricting device in the dratt

tube

Ot primary interest were the trends in the change of

2

turbine performance with the amount ot draft tube tlow

area To this end complete turbine charaeteristiea were

not obtained tor 0ach device inserted in the draft tube

It was considered sutt1e1ent to obtain data tor the tull

speed range tor two representative gat openings one

greater and one less than the rated gate openingbull

Before proceeding with th report ot this 1nvest1gabull

t1on it 1a desirable to supply sa b ckground m terial

on reaction tw-blnes and their dratt tubes

B Raot1on 1rbinea

A hydraulic turbine is a device for converting the

energy in water to eohanical energy (6 Pbull 93lbull96S) furbull

b1nes may be loosely grouped into one of three elasse

impulsmiddote 1 reaot1on or propeller

An impulse turbine normally operates under a high head

and with a relatively sma~l amount ot watel in the converbull

sion or kinetic nergy to mechanical energy The propeller

turbine utilizes pressure energy to develop mechanical

energy while under a low head and p ss1ng a large amount of

waver

The reaction turbine lies somewhere between these two

extremes It changes both pressure and kinetic energy

while oper ting under a medium head with a moderate ount

opound water An example or a reaction turbine is pietur d in

Figure 1

lhe terms of high low small and so tomiddotrth are only

relative in sense A turbinebulls class1f1 eat1on is depenfent

upon its hoad rate of diacharge and speed of rot tion A

useful index tor turbine comparison (5 Pbull 825) is termed

specific speed and this ia a function of the rated ipeed

power output and head or the turbine The common range in

values ot speoitic speed ($ Pbull 826 ) tor each type ot tlirshy

bine is

Impulse J to SS tor one nozzle)Reaction bull 22 to 80 Propeller - 85 to 170

The development of t he reaction turbine began in the

early part or the nineteenth century (26 Pbull 1217bull1)6)

The trst efficient inward tlow turbine was de igned by

James B Francis an American in 1649bull For many years

turbine design was a matter of cutbullandbulltry in America an4

pure mathematical analysis 1n Europe It was not until the

two schools began exchanging ideas in the l$tter halt ot

the n1neteenth century that pronounced advancement was made

in the field

ObTioual7 the primary pux-pose ot any turbine inatallabull

t1on is t he production of power Added to this is the

restriction that the production or power must necessarily

be a controlled process An example of this is where the

turbine is direct-connected to an electric generator which

4

Figure 1 - 135 Inch Reaction Turbine

5

must operate at a constant speed or rotation even though _

the power demand ohangos In thiamp case the turbine nuet

be eap~able or producing a range of power output yet menshy

ta1n e eonetant speed

Speed regulation of the turbine iv accomplished by

means ot a governor (23 Pbull 24bull3-7) bull The contr-ol or regulashy

tion 1s indirect that i s the governor actually exereiaabull

control over the water in order to JJaintain e given speed

Co-ntrol over- the turbine end bence its speed and

power is the function ot a ring of movable wicket gates

located just upsttteam of the turbine runner These w1eket

gates 1n the process of opening and closing upon eeeh

0~1ar in a rotational manner actually control the amount

velocity and direction of tne water passing throu~~ them

C Draft Tubes

It has been found that the effeetive head on a reae

1l1on middotturbine is increased with the addi timiddoton of a draft tube

(3 Pbull 256bull264) Tne draft tube does thin by~

(1) Making a greater presaure d~op across the turbine

possible by the creation of a negative pressure at the

discharge or the runner and

2) DeoreaGing the k1net1e energy lost by increasing

the eross sectional area at exit

he draft tube permits the turbine runner to be

6

located above the tail race water surface without the

sacrifice of head However cavitation will cause pitting

of the turbine if the difference in elevation is too great

A common maximum elevation difference is 19 feet although

this figure is quite subject to modification between difshy

ferent installations (3 p middot 264-266)

There are many different types or draft tubes in use

today the choice or type being largely a matter or

economics (2$ p 368-370) A very common type particushy

larly among the smaller units is vertical with flaring

sides However the angle of flare is limited by the possishy

bility of separation of the flow from the sides In order

to achieve a certain discharge area the length of the tube

may be such as to require a great deal of excavation In

oases or this sort the cost of this excavation must be

balanced against a more elaborate design that does not

require as much excavation Other draft tubes in use

include the elbow hydracone and spreader types

Despite the differences found in construction and

design the draft tube must accomplish the desired objecshy

tives while offering a good hydraulic geometry to the flow

passing through it An inefficient draft tube defeats its

own purpose

Ohapter II

DISCUSSION ~ TURBINE LOSSES

A General

lhe head that 1a actually utilized by the turbine 1a

less than the effective bead as defined by equation ($) by

the amount that 1a lost due to mechanical and hydraulic

reasons

Mechanical loaaea are a function or the turbine 8p$ed

fhis ia not a lineaz- function but varies eomewhere between

N and N2 (3- Pbull 224)

Hydraulic losses encounteled in turbines ma- be subshy

divided aa to the location or occurrence (3 p 225-227) aa

fOllOW$S

(1) Penstock and scroll case

(2) Wicket gates

(3) Between wicket gates and turbine runner

(4) Runner passages

(5) Runner exit into draft tube

(6) Draft tube and

(7) At exit from the draft tube

The flow in the penstock scroll case wicket gates

runner passages and draft tube may be envisioned as

examples of flew in conventional pipes elbows and convergbull

1ng passages If this comparison may be made it could be

assumed that the losses encountered in these locations

would be proportional to vn ~ value ot N is normally2g

aesU111ed to be 2

he losses encountered between the wicket gates an4

the turbine runner and exit lossos are special cases which

will be discussed separately

B Shock toes_

The flow betwe n the wicket gat outlet and the runner

blade entrance is or particular 1nt rest because no direct

comparison vith common flow situations is obvious

Conaider the vector diagram (7 Pbull 7576) in Figure 2

The veetoo v1 is the absolute entering velocity of the

water and is fixed in magnitude and direction by the setbull

ting or the wicket gates The vector l11 1e the peripheztal

velocity of the runnel which tol any given turbine 1e

dependent only upon the turbine rotational speed The

combination of these two vectors ylelda the third vector

v1 which is the relative entering velocity ot the water

nere is only one setting ot the wicket gates for a

given turbine a peed that will produce an angle B1 which

coincides with the blade angle B1bull At other gate settings

the vector v1 will rotate and change in magnitude in such a

9

t ehion that B1 will beoome either greater or 1 sa than B1bull Th1 give rise to tbe phenomenon term d shock loasft

If B1 1a greater than B1 the relative ent ring veloebull

ityt v1 will have a compon~nt opposing the forward motion

of the runner The shock loss could be typified bullbull that

occasioned by direct impact or the water 0n the blade- If

E1 is lese than a] the vector l will overshoot the blade

and the flow will tend to eddy around the forward portion

or the blade tip

The shock loss can then be either due to impact or

eddying flow Since the area norm 1 to the radius at outlampt

of the w1eket gftee is essentially equ 1 to the area normnl

to the rad1u~ at the inlet to the turbine runner the combull

ponents ot vl and vl perpendicular to ul will b approxishy

mately equal This leads to the conclusion that xxbull ~epresenting the shock vector 1 parallel to Ulbull

For either the impact or eddy case the trigonometric

law of $1nee leads tot

XX

bull ul - sin (Bi-Al) vl eln Bi

It it 1a assumed that the energy lost in the shock 1a

the Telocity head ot the shock component XX then

10

VELOCITY VECTOR DIAGIWI

TYPES OF SHOCK LOSS

xbull X

IMPACT BDDJ

XX 1a Teloc1t7 caponent ot shock

Figure 2 - ~bine Runner Vector Diagram$ and Shock Loss Diagrams

11

2 shock loss (XX gt2g

C =sin (BimiddotAl)Let (1)sin Bi

(UlmiddotCV1)2Then shock loabull (2)- 2g

For a given gate opening C ia a constant ranging

from about 14 to 10 For a well designed wheel it is to middot

be expected that C would be approximately equal to U1V1

at rated conditions ie at point of maximum efficiency

This point will occur in the neighborhood of 3~ to 78

gate opening for moat turbines For overgate conditions

the angle A1 becomes larger so the value of C would

decrease For gate openings below rated conditions t he

angle A1 decreases and C would decrease One could expect

a fairly uniform decrease in t he value of C as the gate is

closed from t he overgate position

The velocity v1 is approximately constant for any

turbine speed since the area and rate of flow both decrease

fairly uniformly However for a given gate opening the

velocity V1 will decrease with increased turbine speed

From the foregoing comments and equation (2) the

following trends can be established

(1) For constant turbine speed the shook loss curve

will be close to parabolic in shape concave upward and

have its maximum near t he point of complete gate closure

--

12

and its minimum near the rated gate position

(2) For conatant gate opening the shook loss curve

will approximate a symmetrical parabola with its vertex

the point of minimum loas located at the rated condition

of operation (7 Pbull 79)

c Exit Loas

It can be seen from Figure 2 that the exit loss from

the turbine would be v222g if no draft tube were present

The addition of a draft tube permits the gradual reduction

of velocity by an increase in cross sectional area between

the exit of the runner and the exit from the draft tube

The exit loss and the frictional loss encountered in

the draft tube may be placed together in the expression

m va2 (3)Exit Loss ~---2g

For the ideal case of no friction in the draft tube

m is equal to the square of the ratio of the area at exit

from the runner to the area at exit from the draft tube

In an actual turbine installation however friction

will change the value of m (7 p 84-85) to somewhere

between that for the ideal case and a maximum ot 10

In the interest of maintaining a minimum exit loss

the turbine should be designed and operated so the velocity

V2 will be minimum This will occur when the discharge

13

vector is at right angles to the tangent to the runnerbull

ie the angle A2 1e ninety degree bull It ia to be expected

that this condition will be tultilled near the design con~

d1t1ons ot the ~bine

Current design praetiee 1 to have a small component

ot v2 in th$ direction of turbine rotation at rated condibull

tion$ ltS p 938)

For a constant turbine speed the d1seharg or exit

loss is ess nti lly a constant

For a constant gate opening the exit lo s curve is

aptrroximately a symmetrical pa~abola with ita vert x the

point or minimum loss located at a slightly lowe~ speed

th n the turbine rated speed (7 Pbull 79)

Chapter III

PROPOSAL OP ALlERMAlE MFTBO 0 CO TROL-A lz ~ Location 2 Control

Thua tar only practice and theoretical aspects appemiddotrbull

taining to present day turbinea have been d1acuaaed It

haa been presented that control over the ~bine ia ezerbull

oiaed b y manipulation of the wicket gatea located 11101led1bull

ately preceding the runner These gate - upon rotation

modify both the magn1tu4e and the direction ot the entering

velocit7 Moreover it has be n shown that a simultaneous

change in these two variables leads to inefficient operabull

tion by the introduction of shock loss he farther the

point of operation a from the rated conditione the more

aerioua ia the ahock loss encountered

Any attempt to better turbine pertorance at other

than rated conditione and tbne flatten the top ot the

etticieney hill8 must concentrate upon the lessening ot

the ahock loaa It 1a a aumed that 1 provement in the

scroll case gates and runners would lequ1re sueh pertecbull

tion 1n machine work and metal$ as to be prohibitively

expensive

It ie surmised that any move to elblinate eYen parbull

tially the shock loss would require separate control ovel

l$

the flow and gate exit angle Since it is improbable that

d1~ect1on could be controlled at any location other than

where the gatea are situated in current turbines it will

be assumed that guide vanes will be necessary regardlesa or the method used to control the rate of flow

The primary purpose ot th se guide vanes 1s that or control over the direction ot the incoming water They

should be free to rotate in much the same manner as ordibull

nary wicket gates in order to exercise control over th

turbine speed

If the rate ot tlov is to be controlled elsewhere it

must be modified either in the penstock or the draft tube

Devices that could be used are standard valves gates

variable orifices variable venturi sections and associated

flow regulating schemes

Alauming it were decided to locate such a device upbull

stream of the turbine it would be necessary to allow disbull

tance tor the flow picture to become reestablished prior to

entry to the turbine A contused flow making transit of

the turbine passages would only contribute additional loesbull

ea Such a distance allowance would be perbapa 20 to So

diameters (2$ Pbull 119-123) In large penstocka th1a would

repreaent a considerable distance Which from the viewbull

points ot convenience and control would be undesirable

Attempts to ascertain the effect or additional tlov

16

reduc ion at the wicket gatctsmiddot wae ade 1n the lfadraulioe middot

Laboratory of Oregon St middot te College in 1933 (20) Three

d1tterent thode ot reducins the tlow were t~ied

(l) Locking in the cloeed position pairs or wicket

gatea located opposite to eaeh o~er on the -periphery ot

the wheel

(2) Locking adjacent gates in an open position by

inserting blocks of wood between them and

()) Suocess1vely looking adjacent gates in the closed

position

The results indicated a arked reduction in both power

and efficiency when compared to the curves tor normal gate

operation However it was demonstrated that it was poae1bull

ble to ahitt the power and tfieiency curve ill relation to

turbine apeed lbis important feature will be diacussed

later

ihe main conclusion of the investigation was that conbull

trol by the conyent1onal wick t gates was auper1or to other

methode egtt control exercised at the gates the aelvebullbull

It would app$ar that the bebullt location tor flow conshy

trol would be in the draft tube since none of the objecbull

tiona prev1ously mentioned wou~d eziat there

As bas been stated previously the sole object or the

17

18

turbine is to produce power as etfic1ently as possible

The equation tor the power output of a turbine () Pbull 227)

PaWHe HP (4)55o bull bull Assuming the head 1a constant and a g te located in

the draft tube decreases bhe rate ot flow the power eu

only be increased if the etticiency increases

The ettective head Gn the turbine 1s conventionally

d r1ned as the difference between the auma ot the elevashy

tion head pressure head and velocity head at the entrance

to the turbine casing and the tailrace ($ Pbull 872)

lt ie recognized that the theoretical treatment ot

shock loss as given is highly approximate and serves only

to dictate certain trenda For example the area at xit

rom the wicket g tea CfUl be measuPed with some exactness

but there exists no guarantee that the wateP particles will

complet-ely fill the apace oz- will exit at the establiahed

g te angle The same can be said of the exit trom the

runner blades AssUIlptiona were implied which would indishy

cate that all water particles passing a given croea section

ampH traveling at the same velocity in the same direction

the e alone are autt1c1ent to show 11m1tationa in a theoretbull

1eal approach to the problem

Assume a turbine with ordinary wicket gates tor oonbull

trol compared gainst the same turbine with a gate in the

18

draft tttbe tor supplampment1ng control or the rate ot rlow

Let it also be assumed that the two turbines are opershy

ating at the same point It 1s desirable to predict relabull

tive performance of the two turbines 1 this point of

operation is such that edd7 s hook loss ot reasonable proshy

portions is present in the fir t turbine

~ tull erteot of the shock loss will be exper1 need

by- the fir t turbine

lhe second turbine will derive certain advantages 11

the gate in the draft tube is adjusted to reduce the tlov

1n the proper amount Since they vary a the square ot

the veloo1t7bull the lossabull in the aeroll case wiomiddotket gate

and runner passages will decx-ease aetet-r1ng to Figure 2 1

it can be seen that a decreased velocity v1 w-ill reduce the

eddy shock losa

The ent loss in the dJtaft tube of the second turbine

will be the sum ot the tr1ct1onal loss and the velocity

head at ex1t The velocity head dissipated will be greater

due to the closing action or the gate but the reduoed

t~ictional loss which ia a tunction ot the rate of tlow1

will partially balance this

It 1a entirely possible that the net reduction in

losses in the second turbine will lead to a greater ettibull

oiency and more power output than 4eYeloped by the first

turbine

19

In Figure 3 the plot ot power output against turbine

speed for Curv A~ represents the typical family of curvea

tor a reaction turbine Th b st sp ed is the locus ot

points connecting maximum eft1oiency at each gate opening

The operating speed is the coZUJtant turbine apeed which

passes through the point ot maximum efC1ciencr of the turbull

bine The plot of turbine efficiency against power output

for Curve A is also ahown

It the turbine with flow regulation in the dratt tube

oan demonstrate superior power and efficiency at part loads

the effect would be the same as a shifting or the power

curves toward the condition shown fop Curve B 11 Thisbull

illustrates th ultimate case of the uperpoait1on of best

and operating speeds It will be noted that the pet-form~

of the turbine ot Ourve Bu 1a better than that of CUrve

A at part loads because of ita ability to sustain a relabull

tively high etticienoy ovel a Wider range of power output

o Reguireaegts tort Test Velitication

It is desired to deterra1ne the effect on the turbine

performance b) the addition of a gate in the dratt tube

Th step in the teit will bet

(1 To determine the power output and efficiency ot

the turbine tor wicket gate settings above and below rated

conditione for a wide range ot speed

20

CURVEAbull

TURBINE SPSBD TURBID SPEKD

POIBR OOTPOl

Figure 3 - Turbine Performance Curves

21

22

(2 peat (l) with the gate installed in the drat

tube

(3) middot Converting middot all data to a constant head compare the

powere and effioiencies at the same wicket gate setting and

turbin speed tor the two cbullses

If the ddition or the gate indicates an improvement

in power output and efficiency and the powe~ curve shifts

to the right along the turbine apeed scale the advantage

ot draft tube con~ol of the flow will hav been demonshy

strated

Chapter IV

A E9J11pment

ih turbine used in this test is lJ 5 1nch Pelton

reaction turbine with a rated output ot 30 horsepower under

a head of 56 feet at a speed ot 720 reYolutiona per minute

Views of this turbine are hovn in Figures S and 6 The

turbine is installed on a concrete pad located over an open

channel in the Hydraulics Laboratory at Oregon State Colshy

lege The date of manufacture of this turbine was 1915

The water was delivered to the turbine from a sump

reservoir by two pumps operating 1n parallel Each pump 1a

an 8 inch Pelton double suction centrifugal pump witb a

rating of l$00 gallons per minute at a head ot 75 teet with

a speed ot 1175 revolutions per minute Tbe inlet tlange

ot tne turbine is $pprox1mately 18 feet above the center

line of the pump

A direct current generator was coupled to the turbine

to receive tne power d veloped as shown in Figures 4 and 7 The generator is a Spr gue Electrodynamometer rated at SS horsepower with a speed range of 7$0 to l$00 revolut1one

per minute The classification is type LO 26A 2)0 volta

Figure 5 - View of Test Turbine

Figure 6 ~ View of Test Turbine

and 149 amperes lbe generator ti ld was aepar tely

excited using direct current from a motor g n r tor ampt

(l$ p 4~8)

The power output of the generator waa dissipated in

the water rheostat (3 p 488-489) shown in Figures 9 and

10 The galvanized tank contain d water ot variable d pth

on an electrode ot cast iron m aauring 1bull x 1 x 1

In the initial installation of the turbine it was

intended that the power output should be measured with a

Prony brak bull For th purpoa68 or this teat it was decided

that the brake was too instable and the generator was

substituted The platform for raising the generator the

nee asary two teet for alignment was built out of available

material In this case heavy laminated wood blocks reiashy

torced with other timbers were used and bolted through the

concrete deck (11 Pbull 36-$7)

Due to the light concrete deck the lack ot mas in

the platform and the slight misalignment in the flexible

coupling ao e vibration waa encountered It seemed to

ncr aae linearly to a maximum at the speed of bout 750

revolutions per minute Above this speed no vibPation was

noticeable The vibration waa not se~ere and does not

appear to have materially affected the test results

26

B Intrumentat1on ~ eaeur1ng Devices

The pressure head at inlet to the turbine vaa meaave4

bymeane ot two )6 inch waterbullmeroury manometerbull connected

in series as shown in Figure 8

The terminal voltage ot the generator vas meaeured by

a laboratory voltDleter with a range to )00 yolta and callbull

brated to within 15 Yolta

The armature current bull and hence the line current was

measured by a laboratory ammeter with a range to 150 amperea

and callbrated to w1 thin o 7S amperes

Tae rate ot tlow was established by weight and time

meaeurementa The weighing ank has a capacity ot 121 000

poundsJ the weight belng indicated by Toledo direct reading

scales Timing was done with a hand atop watch with clivibull

aion ot 02 second

he ~ater level in the tailrace was dete~1ned by a

hook gauge lhie was read to the nearest 001 toot

The turbine and generator speeds were eaaured by a

hand tachometer The technique of almost cont1nuoua readbull

ings of the speed gave an error ot no more than 5 revolubull

tiona per minute

c Operational Procedure

Atter the water level in the aump was checked to

insure an adequate auppl7 the puapa were primed and

27

Figure 7 - Test Generator and Plattorm

Figure middot8- Instrument Board and Field Rheostat

28

started After venting they were valved for operation 1n

parallel

The motor generator set was started to supply the

field current and the circuit breaker was closed Water

wa added to the water rheostat to the level shown in

Figure 10 ~ field current wae minimized by cutting in

all the f ield resistance in the field rheostat of Figure 8

The l2 inch gate valve shown in Figures 5 and 6 waa

slowly opened and the turbine and generator brought up to

speed The 12 inch gat valve and turbine were vented and

the pumps were checked to insure neither had lost ita prime

lhe water rheostat offers very steady load 1f the

water level is essentially constant and the water temperabull

ture 1a fixed () p 488~89) In order to maintain this

constant temperature it was decided not to circulate the

water in the rheostat but rather to allow the water to

boil thua achieving the desired result A standing wave

was set up on the face ot the electrode by the boiling

action but a atable load was eatablished except at very

low water leYels where th11 agitation led to fluctuationa

in the line current

After putting the turbine and generator on the line

maximum power was dissipated in the rheostat by redueing

the turbine speed to between oSO and Soo revolutions per

minute Salt vas added to the rheoetat wat r to increasemiddot

29

Figure 9 - View of Water Rheostat

Figure 10 - View of Water Rheostat

Separate Field ExcitationFrom Motor-Generator set Compound Water-Mercury

---shy

re Manometer

I Q)

~ 0

~

Book Gauge

Open Channel

I

Slap Reservoir

Figure 11 - Wat~r Flow Diagram and Electrical Layout

31

waiting pe~iod ot perhaps an h~ followed

while the boiling point or the water wbulls reacbe4 During

this ti+ne the manometer was vented end eheoked electrical

measur1ng 1nstlUments were connected end the hook gauge was

adjusted tor elevation

It required about two- houtte tor the generator to reach

its normal operating tempe-ratu~e_ After the water in the

rheostat and generator had reached their operating temperabull

turea it was possible to begin the taking of data

The only vaPiable which was controlled wee the turbineshy

generator speed However the upper l1ut1t of safe line

current was slightly over 100 ampJilPampPes and the eireuit

breaker would open when the current reached lOS ~ere bull

Control was exercised by means ot regulating the water

level and salt 1n the water rheo tat and the res1stsnoe of

the tield rheost t~

The etfeet ot each type ot regulation on the three

variables is shown below

Volta Aaperebull Speed

Inc Dec Inc Dee~ Inc Dec

Wa~e1 Level Inc Dec~ X

X X X X

X

Salt Concentration

Inc Dec X

X X X X

X

field Resistance

Inc Dec

X X

X X

X X

32

Jlot all methods gave the ame amount ot change in a

given variable and a period of experiment and trial led to

the following scheme starting the rune with the lowest

turbine speed the water level was high with a high amount

ot salt and the field resistance was cut completely out

Aa it became necessary to increase the speed tor each

aucceasive run either cutting in t he field resistance

decreasing the salt concentration or lowering the Vater

level would produce the desired result However decreasbull

1ng the salt concentration had to be done Without a net

gain in water which led to a tluahing procedure that was

not particularly good because cold water was introduced

which required time to heat to the boiling point Cutting

1n additional field resistance was a good method but th1a

increased the amperage possibly to the point of opening

the circuit breaker Lowering the water level was aatiashy

factol1 until the level got too low causing the current

fluctuation previously mentioned Actually it turned out

that a combination of lowering the water level and cutting

field resistance in would carry the speed from ita minimum

to 1ts maximum value it the proper choice were made each

time the speed waa to be changed At the conclusion of

each aet of runs at a high speed the water level would be

low and the field resistance high

33

TURBINE

PAD AND DECK

TAILRACE

WATER SURFACamp

CONCRETE

DRAFT TU1B INSERTS

7 5( DRAFr TUBE

FLltJI ARIA

5~ DRAFT TUBE

FLOI ARSA

Figure 12 - Sketch of Draft Tube and Test Inserts

34

Figure 13 - View of Draft Tube Insert

Figure 14 - View of Draft Tube Insert

D c __ ~s_middot hedu_le of

A number was assigned to each run The fi~st number

applies to the draft tube tlow areas

1 bull 100~ flow area or 0~ oonatriction

2 - 7S tlow area or 2$ conatr1ct1on

3 SoC flow area or so~ constriction

The second number refers to the wicket gate openings

9 over gate opening

6 bull intermediate gate opening

4 bull one h lt gate opening

The third number 14entif1ea the location of the particular

1Wl in a set ot rona made at a given dratt tube tlow area

and wicket gate opening

fnua run number 1bull4bull10 would identity this as the

tenth run ot a set made at halt gate with 75 ot the draft

tube t1ow area

Rune w re made tor a g1yen dratt tube condition

Firat tor tull 41-aft tube flow area seta ot rune were

made for the overgate halt gate and intermediate gate

conditione An insert was placed in t he draft tube and

rune based on the same gate conditions were made tor the

7S~ draft tube flow area case The insert was then changed

to allow only $~ draft tube flow area

The inserts are sketched 1n Figure 12 and photographed

ln Flgurea 13 and 14 They oonaisted of circula~ segments

36

or l2 ineh plywood mount 4 on wooden legs 10 inches high

The 1nse7te were placed in position and secured by th use

ot a-clamps on the legs and the outside ot the bottom of

the draft tube The obvious disadvantage to this method

waa the neoeasity tor draining the water from the tailrace

tor a change ot 1naert The advantage vas of course the

simplicity ot design and construction

Chapter V

DATA-A Original Data

The normal data-taking crew consisted or two men

Assuming adjustments having been made to secure a certain

turbine speed (aee section on Operational Procedure) one

man would take semi-continuous speed readings with the hand

tachometer until a state or rotational equilibrium was

reached This could be only a period or two minutes up to

ten or tifteen minutes As soon as steady speed was

assured the data taking would begin The second man went

to the weighing tank Where a minimum ot three weighingamp

were made The requirement was to get three consecutive

readings such that the ditterence between tbe smallest and

largest time did not exceed 04 seconds The time to

collect a given weight ot water was then assumed to be the

arithmetic average of the three times He then went to the

hook gauge determined the hook elevation and then

recorded the data on the data sheets The first man meanshy

while had taken readings of the line voltage line current

and manometers and checked the turbine speed by multiple

readings During the length of the run all values were

38

checked to determine mean values for recording

The minimum length of one run was about five minutes

If one or more measure ants tended to drift during the run

all values wer discarded and a new run began as soon aa

qu111br1um was stabl1shedo

B -0-al_e_u_l_a_t--d Data

The h d on the tu~bine 1 defined by

($)

The maxtmwm velocity V4 was equal to about o8 tampet per

secon4 which makes it a negligible quantity when converted

into velocity head

An engineerbulla level was used to deterine the d1ffePshy

ence 1n elevation between the compound water-mercury manoshy

meter and the hook gauge Using this value the equation

for turbine bead becomes

where z4 is the hook gauge reading

The rate of flow 1 cent

w weight or water collected average time to collect

The inlet velocity v1 vas calculated by dividing the

weight rate or flow by the specific weight of water and the

)9

area ot ~e inlet pipe This was equivalent to dividing

the weight rate of flow by 490 Then the power input to the turbine is equal to

WHpin rri

10 (6)

Also

(P ~ut) Turbine

(P out) + Generator

(P lost) Generator

The power output of the generator is simplJ the

produot ot the terminal voltage and the armature (line)

curPent The power lost in the generator can be subdivided

into copper losses and stray power losses lo evaluate

these cunes based on losses of an identical generator

11leampsured by the Department ot Mechanical Engineering were

used The loss curves are reppoduced in part in Figures

15 and 16

Determination ot generator losses proceeds as tollowau

(1) From Figure 15 detem1ne the vo1tage drop in the

armature circuit using the temperatures of 1220 F and the

meaaured current

(2) The induced voltage is t~e sum of the terminal

voltage and the voltage drop 1n the armature circuit

() Entering the induced voltage and the turbine speed

into Figure 16 the stray power loss can be determined

(4) The copper lose can be evaluated from Figure 1$

using the measured current and the temperatlll-e of 1220 P

40

25 ~------~--------~--------~------~

U) -U) - 20

f-4 ~

-~ -gt 0

0

VOLTAGE DROP

~ - i -

- bullbullbull bull - -middot-middot -+ ~- + -t--+ ~ - ~ middotbull ~-~ middott- -+----- _ -4 middotmiddot- --~-+-t---r~~ ~--+t-t- - ---t-c-++~-ulf--

0 50 75 100

Figure 15 - Curves of Generator Voltage Drop and Copper Loss

41

1200

1000

800

600

800

0

0

~-

middot--~ 1shy --1 + bull l

100

I -

150 200

IIDOOED VOLTAGB (VOLTS)

Figure 16 - Curves of Generator Stray Power Loss

_ j

-bullshy -L---- shy middot -shy

250

- r

42

(5) The generator los os equal the sum of the eopp r

loss and stray power loss

~e efficiency or the turbine is taken as

etticiency u e =P out (8)Pin

~ample pound Determ1n1gg turbine Power Output

The following data are taken trom that ot Run 1-9-1

Line voltage 1040 volts Line current 870 amperesSpeed 355 revolutions per minute

The induced voltage 1a determined as follows

Line voltage 1040

Voltage drop 90 using Figure 15 with line current of 870 amperes and temperature ot 122 degrees)

Induced Toltage 1130 volta

The power output of the turbine is determined as follows

Generator output 90$0 (line voltage z line current)

Oopper loss 7 (using Figure 15 with line current of 870 amperes and temperatUe or 122 degrees)

Stray power lose 470 (using Figure 16 with speed ot 355 revolutions per miDUte and induced voltage or 1130 volts)

Turbine power output 9527 vatta

or turbine power output 1s 12z2 horsepower

43

The conversion of the calculated data to a constant

head is based on the conventional assumption of constant

efficiency regardless of turbine head For a constant head

ot 81 teet a purely arbitrary figure the tollowing relashy

tionships are ass1lJiled to be true

I ____L (9) (i)l72

(10)

For these two values the specific a peed may be combull

putedt

N t Jt VPt (11)8 243

Chapter VI

~RESULTS

A -Pr_e_ae_n_t_a_t_t_o~n g Reaultbull

Graphical presentation ot the results ot this te1t

are given as follows

Figure 17 -Turbine characteristics with 100~ dratt

tuba 1low area

Figure 18 - Turbine characteristics with 7S dratt

tube tlow area

Figure 19 bull Comparison ot power and etticiency at

over gate conditions between 100 and

75~ draft tube flow area

Figure 20 bull COZQparison of power and ettic1ency at

halt gate conditions between 100~ and

7S~ draft tube flow area

Figure 21 bull Comparison of power and etticiency at

over gate condition between 100~ and

So dratt tube tlow area

Figure 22 - Comparison in variation ot apec1t1c

speed between 100 and 75~ dratt tube

tlow area

50

45

20

-bull - 1--shy40

bull J-~ 30

~ ex

~ 20

~~ ~ -)q

I

~ - _

- -

10~ OF DRAFT TUBE FL(Jif AREA

CONSTANT HEAD OF 8l FEST10

POIER OUTPUT EFFICIENCY SPECIFIC SPEED

0 ~--------------_--------~------~------~ 400 600 800 1000 1200 1400

TURBINE SPEED (RPM)

Figure 17 - Turbine Char~cteristics with 100 Draft Tube Flow Area

50

46

-bulllle

~ 7 ~ OF DRAFt TUBE FLOW AREA

0 -~~-rl C05STAMT BEAD OF 81 mET 1J~

POIER OOTPUT ---+- ---o ~_H EFFICIDCY ~ I shy

bull ql SPECIFIC SPEKD - ~ -

bull ~ J 10 L rmiddotr- r- -

bullz- I

~~ 30 ~~--~----~~-

20 ~ ~ middot-shy

26

~~ 25

~0 ~r-----i (

Tbull -bullshy

400 600 800 1000 1200 1400

TURBINE SPEED (R PK )

Figure 18 -Turbine Characteristics with 75 Draft Tube Flow Area

47

EFFICIENCY 60

1-----shy

-~ 50~--~--~~-~middot middot middot middot r~-~----~~~~---4~-r~-~~gtt

II

POWER~ J ~ bull bull

u I

sH

40~------+-------+---- -~~--~~-~~~~

~----~rl 1 bull

I

I

0~--------------~------_------~--------

~ -OVER GATE CONDITION

COIJSTANT HEAD OF 81 FEET

0 o 10~ DRAFt TUBE

_-- _ 7~ DRAFT TUBamp FLON AREA II

10_~-----+--------r-------r----~~

400 600 800 1000 1200 1400

TURBINE SPEED (RPM)

Figure 19 middot - Comparison between 75 and 100 Draft Tube Flow Areas of Power and Efficiency at Over Gate Conshydition

48

t

bull --4 r ~- ~ middot~

70 1-----------+-~~~~~+middot ~ ~~ middot middot -~~--~~--------~~----~-+1

-~-

Atbull bull

lla-

60

amp0

40

20

10

oampOO

t _ - - ~-+- - -~-

l2 GATB COJIDITIOJJ

COJISTABT HJW) OF 81 JBET

o 0 lOQ( DRAFl TUB8 FLOI AREA

e-- - e 75 DRAFT TUBE FLOW AREA

800 1000

- r-

~

TURBIbull SPBIID (RPII)

Figure 20 - Comparison between 75 and 100 Draft Tube Flow Areas of Power and Efficiency at Half Gate Conshydition

49

60

50

-40

bull 30

IIQbull

20

10

0

400

- t - ~

EFFICIENCY

_J bull - bull bull

~ r r middot t -+ shy L -t -

OVER GAD COliDITIOI

CONSTABT BEAD OF 8l FBB

o o 10~ DRAFt TUBE FLOI ADA middot--- 5~ DRAF TUBE FLQPi AREA

600 800 1000 1200

Figure 21 -Comparison between 50~ and 100~ Draft Tube Flow Areas of Power and Efficiency at Ove~ Gate Conshydition

50

25

20

15

10

0

Figure 22

~- T -4 -t- -l --~-

t-~ I

middot --~- t ~---- _ __ _ + --

----~- --r-- --

~-=J-~-=-~ -==~ _ ~- -- ---f---1 - shy

CONSTANT HEAD OF 81 FEBT

o--o 1~ DRAFT TUBE FLltll AREA

75C DRMT TUBK FLCIJ AREAmiddot--middot-middot 600 800 1000

TURBINE SPEED (RPK)

Comparison of Specific Speeds for 75 and 100 Draft Tube Flow Areas

51

B Discussion 2 Result

Consideration of Figures 17 and 18 indicates the

overall eftioi ncy pattern or hill is significantly or

rounded for the 7$~ flow area than for the 100~ flow area

bia implies a greateP efficiency is possible at speeds

leas than or greater than design speed with an insert in

the draft tube However the muilDum efficiency is lemiddotas

Direct comparison at over gate conditions is made in

Figure 19 ~e same general trend is noted tor both the

etticiency and power curves for the 7$~ flow area case

The eurves show higher values at overspeed than do the

correaponding cWvea for the 100 flow area case It ia

not clear whether the curves have been shifted by the dratt

tube constriction or whether the curves simply bulge past

the normal curves at both overspeed and underspeed condishy

tions The power curves apparently peak near the aeme

point bullalthough maximum power is still obtained with the

normal draft tube area

For the comparison at halt gate operation shown in

Figure 20 a general improvement has apparently been made

by restriction of the draft tube flow area At every speed

the etticienoy and the power is greater for the restricted

tlow case The two ett1o1ency curves and two power curvea

are practically parallel throughout the speed range ot

teat

As the flou aroa i e decreased still farther a s1gn1

ticant change appears Reterr1ng to Figllle 211 tor the $0

flow area curves it a obvious that exit losses have

become excessive at the overgate condition because the

efficiency and power are everywhere leas than tor the case

of normal draf t tube area

Earlier it was pointed out t hat 1t the r esult s 1nd1bull

eated an increase in both power and ef tieiency- t hen it

could be assumed tha t the additional los s i ntroduced with

the draft tube insert is less than the diminished losses

due to leas shock losa and water passage losses For the

places where both the efficiency and power have been

increased we can assume that the insert has improved turshy

bine performance

For the places where the power haa been decreased

nothing can be said as to the elimination of ampbock loss

because the new lose present with the drat tube insert has

overshadowed any gains in eftecti Ve head upatJ-eam of the

insert

Near the peak of the efficiency hill howeve~ it may

be pointed out t hat shock loaa ie a minimum with a normal

draft tube and the insert merely adds an additional loss

with the resultant decrease in maximum efficiency tor the

7$~ flow area case

Perhaps the most s1gn1ticant set of eurves is shown aa

53

Figure 22 In this graph values of specific speed tor the

75 and 100~ flow area cases for both over gate and one

halt gate openings are plotted against turbine speed At

every speed and both gate openings the value ot specific

speed for th 75~ flow area case is greater than that for

the 100 t1ow area ease

Since the head is a constant for both situations this

may be interpreted in either of two ways trom equation

(11)

(1) For the same turbine apeed restriction of the

draft tube t1ow area resulted in greater turbine power

(2) For the same power amputput the turbine with 75~

draft tube flow area operated at a greater speed than did

the one with 100 flow area

Since the required diameter of a turbine varies

inversely with the speed the second interpretation could

be stated such that a smaller turbine could be used to

develop the same power output

Whether viewed trom the aspect of increased power

greater speed or reduced size the performance of the turshy

bine with reduced draft tube flow area is superior to that

with the nolmal flow are in the draft tube

The curve of specmiddotific speed versus turbine speed for

the so draft tube flow area case at over gate cond1t1ona

was not included in Figure 22 This curve lies below that

for the 100~ flow area c se at all speeds

In elaboration ot the second interpretation of Figure

22 attention is directed to the relative magnitudes ot

increased apee1f1c speed tor the two gate openings Assumbull

ing that the increase in specific speed implies a shift ot

the power curve to the right along the turbine speed scale

the power curve would be shifted more tor tbe halt gate

opening than tor the over gate opening

It thia trend could be extrapolated to the other gate

openings the tendency can be seen tor the line ot beat

speed to rotate toward the line of the operating speed as

illustrated in FigtU-e ) The advantage of this has already

been discussed

This particular turbine has a low specific speed tor a

reaction turbine Aa the rated value of apecitic apeed tor

reaction turbines increases the line ot beat speed departs

even more radically from the line of operating bullpeed It a

test similar to this were conducted on a reaction turbine

ot gleater specific speed it is pJobable t hat the rotation

ot the line of beat apeed would become more p~onounced

The scheme used in th1a teat had two obvious dr wbull

backs The first was the decision to leave all the wicket

gamiddottes installed tor all conditions ot the draft tube

These gates predominated in control of the tlow The

inserts added to the draft tube merely acted as auxiliary

55

contrGla

The aecond drawback was the choice or device to place

in the draft tube The reasons foll selection of this type

of device have been previously mentioned It is to be

anticipated that adaptation ot dratt tube flow control

would result 1n a better device for an actual turbine

installation Such apparatus might take the form of a

pneumatic bladder or a h7drau11oally operated variable

venturi section in the draft tube It is conceivable that

the gate as used in this test might be adapted also

Chapter VII

OONCLtJSIOfS

From the results of this test the following eonolubull

e1ona aa to the effect ot a variable draft tube flow area

on the performance or a r action turbine may be drawn

(1) The effect ot a variable draft tube tlow area 1a

generally favorable upon the operat1Gn ot a reaction turbull

bine because or the tendency tor the line or beat speed to

rotate toward the line ot operation This resulte in

better performance of the turbine at partbullloads

(2) he etf1o1ency eh111 tor the turbine beeomaa JDore

tlat at the top leading to a smaller max1JilWD effic1enc7

but e reater etticieney at other pointe of operation with

the insertion ot an auxiliary control ror the rate ot tlov

in the draft tube

(3) The power output of the turbine will increase at

over speed over gate conditione as well a at part gate

conditions with the proper amount or draft tube eonatr1cbull

tion or flow

(4) It is possible to eliminate at least partially

eddy type shock loss by tho introduction ot flow control

in the draft tube

BIBLIOGRAPBl

1 Addison Herbert A treatise on applied h-draul1cs New York Wiley 1954 724 Pbull

2 Allen o M and I A Winter middot Co111parative testa on experimental draft tubes Tranaact1ons ot the American ociety ot Civil Engineers 87t893bull970 1924

3 Barrows a E Water power engineering 3d ed ew York McGraw-Bill 1943 791 Pbull

Bovet G A Modern trenda in hydraulic turbine design4middot in Europe Tranaactions of the American Society ot Mechanical Engineera 75975bull993 1953bull

s Oreager William P and Joel D Justin Hydroelectrichandbook 2d ed New York Wiley 19$0 1151 Pbull

6 Daily Jamea w Hydraulic machinery Int Hunter Rouses Engineering hydraulics Hew York Wiley 19$0 p 8$8bull99

Daughertybull Robert L Bydraulie turbines ew Yorkbull7middot MoGrav-Hlll 1920 281 Pbull

8 Daugherty Robert L Inveat1gat1on of tne performance ot a reaction turbine ~anaactiona or the American Society ot Civil Engineers 7811270bull1304 1915

9 Davie L M Model and prototype testa Int Trend in hydraulle turbine practice symposium lranaactions ot the American Society ot Civil Engineers 1o63S3middot368 1941

lfJ Doland James J Hydro power engineering Hew Yorkbull Ronald 1954 209 Pbull

11 Gandy Theodore s and Elmer c Schacht Direct curshyrent motor and generator troubles operation and repair New York McGraw-Bill 1911 293 Pbull

12 Gibaon Arnold H Hydraulics and ita applications5th ed London Constable 1952 813 Pbull

58

13 Button s P Component loases in Kaplan turbinebull and The prediction of efficiency from model tests Probull coedings of the Institution or Mechanical Engineers168743-762 1954

14 Knapp R T~ Oavit t1on mechanics and its relation to the d sign or hydraulic equip ent Proceedings or tne Institution ot Mechanical Engineers 166150bull16) 1952

15 Langsdorf Alexander s Principles of direct curHnt mach1nee 5th ed New York r~cGrawbullH1ll 1940 746 Pbull

16 Lsrner Chester w Characteristica of modern hydraubull lie turbines Trans e~ions of the ~~erican Society ot Civil Engineers 66306-386 1910

17 Linsley Ray K Jr and Jobulleph B Franzin1 Eleshyments of hydraulic enginebullring New York McGrawshyBill 19$5 $82 Pbull

18 Mead Daniel w Hydraulic machinery llev York McGraw-Hill 1933 396 Pbull

19 ead Daniel w Water power engineering New York McGrawbullRill 191S 843 Pbull

20 Mockmore Charles A Part gate operation at water turbines Corvallis Oregon State College Department ot Civil Engineering 1933 11 numb leaves (Unpubshylshed typescript)

21 Mockmore Oharles A Flow characteristics in elbow dratt tubes Transactions of the Amez-ican Society ot Civil Engineers 103402middot464bull 1938

22 Moody L F Hydraulic machinery In c v Davis Handbook ot applied hydraulics New York McGrawshyHlll 1942 1082 Pbull

2) Ptau At-nold Hydrbullulie turbine handbook ld ed Milwaukee AllisbullOhalmers ManufactUIing Company 1948 70 Pbull

RheingalUI w J Recent developments in Francis turshybines Mechanical Engineering 74189-196 1952

25 Russell George E Hydraulica 5th ed New York Henry Holt 1942 466 Pbull

26 Safford A and E P- Hamilton American mixed tlow turbine and ita setting Tranampactions or the Amerieal Society of Civil Engineers 851237bull1)56 1922

27 bull Spannhake W1lhe1Dh Problems or modern pump and tur b1ne design Transactions of the American Society of Mechanical Engineers 56e22$-248 1934bull

28 Sutherlandraquo R A Better ethod or representing and middot tudying water turbine performance ~ansaetions ot thmiddote American Society of Mechanical Engineers 68t675bull 686 1946

29 Teats ot five models or draft tubes tor turbines Engineering News-Record Pbull 182-184 Aug 2 1923

30 White w M American hydztaulic turbines Mechanical Engineering S2t390bull39S 1930bull

31 White w M lhe hydraucGne rega1ner1 its developmentand appl1eat1ons 1n hydroelectric plants Meohanlobulll Engineering 43t37Sbull380 1921 middot

32 Winter I A Economic principlebull in designbull Int Trend in hydraulic urbin practice bull a ampoeiumTranaaot1ona ot the American Society ot Civil Engineerslo6332bull3S2 1941

33 Wiel1cenua G F Fluid mechan1ca or turbo-machineryNev York McGraw-Hill 1947 613 Pbull

APPENDICES

c

Appendix A

NOATIOB

A Angle between the absolute velocity vector and the tangent to the rwmer Subscripts 1 and 2 refel to entrance and exit ot the runner blade

B Angle between the relative 1elooity vector and the tangent to the rwmer Subscripta 1 and 2 refer to entrance and ezit or the runner blade

Angle between the tangent to the runner blade tip and the tangent to the runnel- Subscripts 1 and 2 reter to entrance and exit of the rt1rmer bladebull

Blade angle-gate opening conetant defined by equation (1)

e 09erall efficiency

g Gravitational acceleration assumed constant at 322 teet per second per second bull

H Turbine head detined by equation ($)

m Exit loss coeft1e1ent

Turbine speed expressed in revolutions per minute

Turbine speed under a constant head of 81 teet

specitic apeed of the turbine under a constant head ot 81 teet

p Power output in horsepower ot the tvbine

Power output of the turbine Ulder a constant head ot Sl teet

Pl- Pressure head at entrance to the tUlb1new

l1 Peripheral velocity ot the runneP Subacr1pta 1 and 2 refer to entrance and exit ot the JUnllampr blade

62

v Relative velocity reaulting trom the combination ot the absolute water velocity V and the runner periphshyeral velocity u Subscripts 1 and 2 refer to entrance and exit ot the runner blade

v] Relative velocity vector necessary to produce a tanbull gential entry into the runner blades

V Absolute water velocity Subscripts l and 2 refer to entrano and exit ot the runner blade

v2 Velocity head Subscripts 1 and 4 reter to the ~8 entrance to the turbine and the tail~ace wate~

w Unit weight ot water assumed constant at 624 pounda per cubic toot

V Weight rate ot flow in pounds per aeooncl

XX Velocity component ot ahook See Figule 2

Z Elevation head Subscripts 1 and 4 reter to entrance to the turbine and the taibace water surfacebull

Appendix B ORIGINAL DATA-Run

lfwnber

0-4-1 0-4-2 0-4-3 o-4-4 o-4-S o-4-6 0-4-7 0-4-8 0-4-9o-4-lo o-4-11 o-4-12 0-4-13

o-6-1 o-6-2 06-3 o-6-4o-6middotS o-6-6 o-6-7 o-6-8 0-6-9 o--6-lo o-6-11

Speed

rmiddot2middotbullmiddot(1)

336 38$ 451 S$9 620 669 6lt)$ 120 787 860 932

102imiddot109 bull

352 355 443middot 543middot 620 654AJs32

911 1001 1111

~essure Head rt (2)

410 410 416 426 431 43-7 439 44-9 452 467 482 soo $1 bull $

350 351 35middot7 )66 37-9 37-9 392 41 bull 3 43middot3 460 489

Elevation Bead

fjj $7 $7 $7 $7 $7 $7 51 57 5-15858 $8 58 56 56 $6565656 51 575As5a

Velocit Head

flj 07 07 07 06 06 06 06 os 05 os0404 03

09 09 oa o8 o8 os 07 07 06 o~o

Total Head rt ($)

47middot4 4A44 o 489 49-4 soo $02 $11 $14 $29 5imiddot45 2 576

41 bull $ 416 421 430 44middot3 44middot3 456 47-7 496 523551

Plow

lbtjec

326 324middot317 311 306 30029middot28 middotmiddot middot 386 275middot260 240 218

359 36~35 bull 349 345middot 339 330 318 300 273 240

Line Potential

vyqjbull 1060 1220 ~-0o 1920 2150 2000 2$60 2000 1940 18)015io11 o

1000 1100 139bull5 1760 1925 16$0 1620 1610 1540 1330 870

Line Current

amlscs 960 900 830 740 730655 70bull 0 530 660 600 5imiddot54 6 )60

982 930 860 780 ~3-545

79-5 74-5 670 560 370

P

Appendix B ORIGINAL DATA (Continued)

Run Number

Speed

Pbulltmiddotbullmiddot )

leasure Head ft(2

Elevation Head tt(J)

Velocity He-dfmiddotj

Total Bead tt($

Flow

lbstsec( )

Line Potential vo~ta( )

Line Current

amjs (sect

0bulllt)-1 0-9-2

3ll6 398

28o ~~1

$6 56

1o 10

346 347

390 365

1ooo 1190

aao 835

0-9-3 0-9-4 o-9-S

472 565 632

292 305 312

$6 s6 56

10 o9 o9

)$8 J7~o 37~7

381376 37o

1)6614oo 141o

820 ass ass o-9-6 0-9-7 0-9-8 o-9-9 0middot9-10

680 120 762 844 920

)24337346 366 390

56 $6 56 57 $7

09 os o8 oa 07

)89401 410 431454

367~ 357348 34o 322

1400 1J6o l36o 1310 1170

843 820 7957So 67~0

0-9-ll 0-912

1001 1100

41 bull 7 45-3

s 7 6~0

06 os 480 $18

299 268

980 65$

560 36~5

1-4-1 1-4-21-4-l1-4shy1-4-5 1-4-6 l-4-7 1 4-8 1-4-9 1-4-10 1middot4-ll 1-4bull12

354middot452 562 62q 674shy102 752 760- 863 932

1022 1100-

)82389 4014oa 416 41--7 423 428 44-2 45-7 486 49-2

51S757 51 5-7 5middot15zs sa $8 58 59

07 07 06 06 06 06 06 os o bull o 04 o J

446 45-)46middot4 471 ti7-9480 q86 491505 $19 548 55-4

)28 320 311 306 300 295 291 286 269 2582iimiddot21 bull

1080 14Lo 1550 153-5 1470 141-0 1385 1310 1310 1230 1120 855

970855 875 91-0 94~0 975 966 995 860 77-S 610 4fo

0 ~

Appendix B ORIGINAL DATA (Contirmed)-Run Speed Pressure Elevation Velocity Total Flow Line Line

Number Head Head Head had Potential Current rtjjmbull t~ bttec vyfs am~a12) ( ) ti fli 8

1-6-l $6 33$ $6 0bull9 400 364 1100 93 0 1-6-2 41 34laquo2 $6 oa 406 JS7middot iios a5s l-6-3 500 3~0 5bull6 os 356 1 1 o aos 41middot~1-6~4 35bull4 5-6 oa 41middot 352 16~0 82 0 5~1-6-5 5 bull 36_2 Sbull6 08 42bull6 349middot 161 ~ 0 86~0 1-6-6 622 366 $6 oe 43bull0 345middot 158 0 88~$ 16-A 649bull 37bull1 56 os 43-S 342middot 1570 895 1~- 386 57 07 46-0 192 ) 125A44 333middot 1-6-9 3) 404 5middot1 07 468 317 1620 675 1610 911 42-4 5-7 o6 48-7 298 168 0 61 0 1-6-11 999 451 56 os Sl ll 276 ~2-0 530 1-612 1115 485 58 04 54middot7 238 90 )3 0

1middot9-l 355 279 56 10 )45 385 1040 870 1-9-2 399 28J $6 10 )49 38$ 1140 86 5 l-9-3 ~ ao 291 56 ~0 35middot1 J8J_ JJ6o 815 1bull9-4 579 303 56 09 )68 375middot J4JO 830 l-9bullS 40- 313 )6 09 31middot8 370- 1460 82~0 1-9bull6 679 2) 56 09 3 bull8 364middot 1670 710 l-9-7 682 319 56 o9 384 ) 62 1460 79 5 l-9-8 724 33middot5 56 o8 399 3$6 bull 1480 76 -5 1-9-9 762 34middot3 $6 0 bull 8 407 )48 14910 13middotS 1-9-10 833middot )60 5middot7 os 42$ 339 144$ 686 1-9-ll 926 39middot1 5-7 07 455 318 1290 600 1-9-12 1000 41middot3 0-6 476 298 1115 510$ ~ 1middot9-13 1105 452 s o4 $14 2$6 710 )10

~

Appendix Bt ORIGDIAL J (Continued)

Run Speed Pressure Elevation Velocity Total Plow Line Line Number Head ltead Head jlamp$d P()ten~ibulll Current

r~~~m ft ft lbs~seo voltattj rgj twimiddot t 1 t2gt lt3 ou t ( rt

2-9-1 384 289 S 6 10 35 5 1400 1170 810 2-9-2 443middot 29$ $6 ltimiddot9 360 379middot 11(0 87$ 2-9-J 536 30bull 3 sc 09 )68 374middot 1)40 84 bull) 2-9-4 571 306 $6 09 3~1 372 120bull 0 955 2-9-5 623 316 S6 09 J l )6S UJSo 77$ 2bull9-6 669 327 S6 09 )92 )61 1240 905 2-9bull7 712 )39 56 os 40-3 351 12(0 86 bull0 2-9-8 ~5$~ J48 56 oa 412 348 1290 81 bull ) 2-9-9 04 )63 56 oa 42-7 339 12ltJO 76$ 2middotmiddot9-10 8$2 376 5middot1 07 440 33~- ~ o 710 2-9-11 955 394 5-1 o6 457 300 1100 506 2middot9-12 1000 421 $7 06 48middoti 295 1020 $18 2-9bull13 110~ 463 56 05 $2 267 620 3~0

oshy0

Appendix Gt CALCULATED DAgA

Turbine Run Generator Generator Turbine Turbine Efficiency Turbine Turbine Specit1c

Number OutputKWlt21

Loa~Jes KWlol

Outut K bull (H)

Input RP 12)

middot Percentlt13gt

Speed r~Jmiddot(

0ltput HP ~1

Speed r-m

( 6) middot

o-4-1 0middot4-2 0-4-3 0-4-4 0-4-5 0-4-6 O-qmiddot7o-4-8o-4-9 0-4bull10 0-4-11 o-4-12

1018 1o9a 1220 1)62J40214oa1J4oo 1357 1320 1164 997 718

046 o59 071 092 096 1071oo 134 104 100 109 107

14261sso 17)01948 2008 20322011 1999 19 09 1708 14-84 11o6

281279 27-7 276 215 273271 268 268 26h 258 24-5

soa 555 62$ 705 7)1145 742 74-6714645 51s 45-1

440 sos 585 720 195 sso sao 9$$ 985

1065 1135middot 1230

318 357 319 416 422 419412 39middot9 378 324 260 191

102 12bull4 148 191 21bull 3 22o 233 249 24924middot9 238 221

0-4middot13 418 104 699 228 306 1300 117 18)

o-6-1 982 045 1376 271 $08 496 376 124 o-6-2 o-6-3 G-6-4o-6-5 0-6-6

1023 1200 13 73 J415 139h

051 0middot66 oaa ()bull 96 088

14-39 1696 1958 2026 1986

276 27middot4 273 278 274

$20 61 8 717 7)0726

q95615745 8)5685

390 ll5middot3 sos soo 490

127 170 218 243 2$$

o-6-7 o-6-8 o-6-9o-6-lo

1288 1199 1032 7-45

o9o 094 09$ 096

1846 1733 1511 1128

274 276 271 260

67S 629559 43middot4

980 1085 1165 1245shy

436 )83316 21bull 7

266 276 270 239

0-6-11 322 1oo 566 2141 2JS 1350 101 177 0 --4

Appendix C CALCULATED DAlA ( Continued)-Run

Number Generator Generator

Out2ut Losaes xw LW- 12gt (lO)

Turbine Out2ut

ltPlJ

Turbine Inat lfP Jig)

Etpound1e1ency

PireentDl

Turbine Sed x-~m( 1

Turbine OutEut RPJl)

Turbine Specific

SeeedrIbullntbull

( 6)

o-9middot1 0-9-2 0-9-3 o-lt)-4 09-$ 0bull9-6 0-9-7 0-9-8 0-9-9 0-9-10 o-9-11 0-9-12

aao 994

111$ 1197 1206 1180 11)21081 982 784 5-49 2)9

0middot45oss o6$ 070 07$ 0-77 (l77 or~ o s06o 8 096

123~ 1402 1$80 1698 17bulllS 168$ 16bull18 ~middot5430 1151 a~J4 9

24middotgt24middot3248 25~25 260 260 259 267 266 26middot1 2S2

sos 577 63-7 671 676 650 621 60036J4

327 178

$) 610AlO 3$

92S 980

102$ 1070 1157middot 1230 1300 137Smiddot

44middot4 soo 523 ssomiddot 540so6 46-5 432 368 274 18~8

J46 176 21-1 255 2802s_A 28 289 288 265 231 168

1-4-1 1-4middot2 1-4-3 1-4-4 1-4-5 1-4-6 1-4-7 1-J-8 1-4~9 1-4-10 1-4-11 1-4-12

10bull48 1231 13-S6 1397 1)821375 1))8 1303 1127 953 683) 51

048 067 o7A07 0 bull79 oa1 oss o bullao osa 0lt)0 096 099

J468 1740 1921 1978 1958 19$1 1911 lSSi162 1)98 1045

603

266 264 262 262 261 2512$7 2$6 24middot7 24-3 233 217

551 660 13middot3155 75-6 7~-97 middot4 72$ 67 51middotJ 44middot9 21middot1

475 605 A4220

875middot 910 970_

1000 1090bull 1166 1243 1330

5816

44middot444middot5 430 427 412 392 329 273 188 l0-7

117 101 204 22$ 2)7245 2562sa 257251 222 179

a-C))

Appendix Ct CALCULATED -DATA ( Ocntinued)

1-6middot1 1023 o$2 14-41 26S 505 41~6 26~

54middot5 13middot3l-6-2 1201 067 1boo 625 47-9 17shy~middot41-6bull3 1296 oA9 1 middot43 26 9 700 so5 20bull 4 l-6-4 l3j5 o 0 19~09 268 71bull3 A5o 514 222 1-6-5 1) 5 o81 19(gt4 271 725 51-5 238 l-66 1398 081 198) 27-0 736 8 S13 252~-middot l-6j 1405 083 199i 211 733 885 $middot06 2$9 l-6 13middot9~ 103 2amp 0 279 71 8 985~ 467 ~-69 1228 1 bull 02 17-SS 270 661 109$ 407 ~3~ l-6bull10 1025 100 lSll 26i 573 1175middot 27~S32middot~l-ampu 153 1-00 llft3 26 444 1270 22 24bull8 1bull6-12 294 100 52a 231 22 3 1360 95 172

1-9bull1 904 048 1275 2J4Z $28 S4$ 459 1$2 1-92 98$ oss 13-92 24middot4 57-0 6JO 49bull1 176 1-9middot3 1110 066 1$76 24middot9 63middot4 I2o 536 21-7 l--9-4 1187 072 1685 251 66$ 5 $$ bull 0 261 1middot9-5 llltJ7 1710 25middot4 67-3 93$ 536 28~20-671middot9-6 1186 o 8 1708 25-7 67) 980 $15 2691-9- 1161 oBo 1660 2$middot3 6$6 990 508 29-1 l~- ll-32 oB) 16sect0 2$8 632 1030 471 291 1-9bull9 109$ oa5 2$7 614 1075 29S~middot 0 4imiddot41-9-10 9~91 oas 262 S$1 1150~ 3 o 292 1-9-11 o9o u57 12JiO 21gt 26-77middot74

-45 26sect ~middot91-912 $69 091 sas 25 middot3 1)0$ 196 2J-8 1-9-1) 220 098 426 2)9 178 1390middot 84 16 6

0 0

Appendx C CALCULATED DATA (Continued)

Turbine Run Generator Generator lurbine Turbine Eft1e1eney Turbine lurbine Spee1f1c

Number Output Losses Outit Input Speed Output SPed middot k_-V KW R _ H_bull_P Percent r Thm HP rpm_ (9) tlo) 11) middot (12 _) (lJI ( ) (1$ (14)

2-9-1 9--46 055 1)62 258 528 580 164 2-9-2 1024 056 248 58 4 665 4 9 191iimiddot48 4~middot0 2-9-3 1132 067 05 2$0 641 795 52q 237 2-9-4 1148 065 1027 2$1 -~8 845 525 252 2-9-5 11 77 oso 16-83 253 6 910~ 522 270 2-9 6 1122 071 1600 251 622 960 47-5 2722-9-A 1092 015 1562 257 608 1010 445 2z12bull9- 1052 079 1514 261 580 1060 41middot7 2 2 2middot9-9 986 o82 ]429 26) 542 1105 372 277 2-9-10 915 086 1340 268 500 1160 334 27-6 2-9-11 638 087 972 254 )81 1270~ 229 250 2-9-12 )28 090 828 259 )19 1295 179 226 2-9-13 192 094 383 2$ 6 150 1370 7 3 152

-3 0

Page 9: The Effect of A Variable Draft Tube Flow Area on the

2

turbine performance with the amount ot draft tube tlow

area To this end complete turbine charaeteristiea were

not obtained tor 0ach device inserted in the draft tube

It was considered sutt1e1ent to obtain data tor the tull

speed range tor two representative gat openings one

greater and one less than the rated gate openingbull

Before proceeding with th report ot this 1nvest1gabull

t1on it 1a desirable to supply sa b ckground m terial

on reaction tw-blnes and their dratt tubes

B Raot1on 1rbinea

A hydraulic turbine is a device for converting the

energy in water to eohanical energy (6 Pbull 93lbull96S) furbull

b1nes may be loosely grouped into one of three elasse

impulsmiddote 1 reaot1on or propeller

An impulse turbine normally operates under a high head

and with a relatively sma~l amount ot watel in the converbull

sion or kinetic nergy to mechanical energy The propeller

turbine utilizes pressure energy to develop mechanical

energy while under a low head and p ss1ng a large amount of

waver

The reaction turbine lies somewhere between these two

extremes It changes both pressure and kinetic energy

while oper ting under a medium head with a moderate ount

opound water An example or a reaction turbine is pietur d in

Figure 1

lhe terms of high low small and so tomiddotrth are only

relative in sense A turbinebulls class1f1 eat1on is depenfent

upon its hoad rate of diacharge and speed of rot tion A

useful index tor turbine comparison (5 Pbull 825) is termed

specific speed and this ia a function of the rated ipeed

power output and head or the turbine The common range in

values ot speoitic speed ($ Pbull 826 ) tor each type ot tlirshy

bine is

Impulse J to SS tor one nozzle)Reaction bull 22 to 80 Propeller - 85 to 170

The development of t he reaction turbine began in the

early part or the nineteenth century (26 Pbull 1217bull1)6)

The trst efficient inward tlow turbine was de igned by

James B Francis an American in 1649bull For many years

turbine design was a matter of cutbullandbulltry in America an4

pure mathematical analysis 1n Europe It was not until the

two schools began exchanging ideas in the l$tter halt ot

the n1neteenth century that pronounced advancement was made

in the field

ObTioual7 the primary pux-pose ot any turbine inatallabull

t1on is t he production of power Added to this is the

restriction that the production or power must necessarily

be a controlled process An example of this is where the

turbine is direct-connected to an electric generator which

4

Figure 1 - 135 Inch Reaction Turbine

5

must operate at a constant speed or rotation even though _

the power demand ohangos In thiamp case the turbine nuet

be eap~able or producing a range of power output yet menshy

ta1n e eonetant speed

Speed regulation of the turbine iv accomplished by

means ot a governor (23 Pbull 24bull3-7) bull The contr-ol or regulashy

tion 1s indirect that i s the governor actually exereiaabull

control over the water in order to JJaintain e given speed

Co-ntrol over- the turbine end bence its speed and

power is the function ot a ring of movable wicket gates

located just upsttteam of the turbine runner These w1eket

gates 1n the process of opening and closing upon eeeh

0~1ar in a rotational manner actually control the amount

velocity and direction of tne water passing throu~~ them

C Draft Tubes

It has been found that the effeetive head on a reae

1l1on middotturbine is increased with the addi timiddoton of a draft tube

(3 Pbull 256bull264) Tne draft tube does thin by~

(1) Making a greater presaure d~op across the turbine

possible by the creation of a negative pressure at the

discharge or the runner and

2) DeoreaGing the k1net1e energy lost by increasing

the eross sectional area at exit

he draft tube permits the turbine runner to be

6

located above the tail race water surface without the

sacrifice of head However cavitation will cause pitting

of the turbine if the difference in elevation is too great

A common maximum elevation difference is 19 feet although

this figure is quite subject to modification between difshy

ferent installations (3 p middot 264-266)

There are many different types or draft tubes in use

today the choice or type being largely a matter or

economics (2$ p 368-370) A very common type particushy

larly among the smaller units is vertical with flaring

sides However the angle of flare is limited by the possishy

bility of separation of the flow from the sides In order

to achieve a certain discharge area the length of the tube

may be such as to require a great deal of excavation In

oases or this sort the cost of this excavation must be

balanced against a more elaborate design that does not

require as much excavation Other draft tubes in use

include the elbow hydracone and spreader types

Despite the differences found in construction and

design the draft tube must accomplish the desired objecshy

tives while offering a good hydraulic geometry to the flow

passing through it An inefficient draft tube defeats its

own purpose

Ohapter II

DISCUSSION ~ TURBINE LOSSES

A General

lhe head that 1a actually utilized by the turbine 1a

less than the effective bead as defined by equation ($) by

the amount that 1a lost due to mechanical and hydraulic

reasons

Mechanical loaaea are a function or the turbine 8p$ed

fhis ia not a lineaz- function but varies eomewhere between

N and N2 (3- Pbull 224)

Hydraulic losses encounteled in turbines ma- be subshy

divided aa to the location or occurrence (3 p 225-227) aa

fOllOW$S

(1) Penstock and scroll case

(2) Wicket gates

(3) Between wicket gates and turbine runner

(4) Runner passages

(5) Runner exit into draft tube

(6) Draft tube and

(7) At exit from the draft tube

The flow in the penstock scroll case wicket gates

runner passages and draft tube may be envisioned as

examples of flew in conventional pipes elbows and convergbull

1ng passages If this comparison may be made it could be

assumed that the losses encountered in these locations

would be proportional to vn ~ value ot N is normally2g

aesU111ed to be 2

he losses encountered between the wicket gates an4

the turbine runner and exit lossos are special cases which

will be discussed separately

B Shock toes_

The flow betwe n the wicket gat outlet and the runner

blade entrance is or particular 1nt rest because no direct

comparison vith common flow situations is obvious

Conaider the vector diagram (7 Pbull 7576) in Figure 2

The veetoo v1 is the absolute entering velocity of the

water and is fixed in magnitude and direction by the setbull

ting or the wicket gates The vector l11 1e the peripheztal

velocity of the runnel which tol any given turbine 1e

dependent only upon the turbine rotational speed The

combination of these two vectors ylelda the third vector

v1 which is the relative entering velocity ot the water

nere is only one setting ot the wicket gates for a

given turbine a peed that will produce an angle B1 which

coincides with the blade angle B1bull At other gate settings

the vector v1 will rotate and change in magnitude in such a

9

t ehion that B1 will beoome either greater or 1 sa than B1bull Th1 give rise to tbe phenomenon term d shock loasft

If B1 1a greater than B1 the relative ent ring veloebull

ityt v1 will have a compon~nt opposing the forward motion

of the runner The shock loss could be typified bullbull that

occasioned by direct impact or the water 0n the blade- If

E1 is lese than a] the vector l will overshoot the blade

and the flow will tend to eddy around the forward portion

or the blade tip

The shock loss can then be either due to impact or

eddying flow Since the area norm 1 to the radius at outlampt

of the w1eket gftee is essentially equ 1 to the area normnl

to the rad1u~ at the inlet to the turbine runner the combull

ponents ot vl and vl perpendicular to ul will b approxishy

mately equal This leads to the conclusion that xxbull ~epresenting the shock vector 1 parallel to Ulbull

For either the impact or eddy case the trigonometric

law of $1nee leads tot

XX

bull ul - sin (Bi-Al) vl eln Bi

It it 1a assumed that the energy lost in the shock 1a

the Telocity head ot the shock component XX then

10

VELOCITY VECTOR DIAGIWI

TYPES OF SHOCK LOSS

xbull X

IMPACT BDDJ

XX 1a Teloc1t7 caponent ot shock

Figure 2 - ~bine Runner Vector Diagram$ and Shock Loss Diagrams

11

2 shock loss (XX gt2g

C =sin (BimiddotAl)Let (1)sin Bi

(UlmiddotCV1)2Then shock loabull (2)- 2g

For a given gate opening C ia a constant ranging

from about 14 to 10 For a well designed wheel it is to middot

be expected that C would be approximately equal to U1V1

at rated conditions ie at point of maximum efficiency

This point will occur in the neighborhood of 3~ to 78

gate opening for moat turbines For overgate conditions

the angle A1 becomes larger so the value of C would

decrease For gate openings below rated conditions t he

angle A1 decreases and C would decrease One could expect

a fairly uniform decrease in t he value of C as the gate is

closed from t he overgate position

The velocity v1 is approximately constant for any

turbine speed since the area and rate of flow both decrease

fairly uniformly However for a given gate opening the

velocity V1 will decrease with increased turbine speed

From the foregoing comments and equation (2) the

following trends can be established

(1) For constant turbine speed the shook loss curve

will be close to parabolic in shape concave upward and

have its maximum near t he point of complete gate closure

--

12

and its minimum near the rated gate position

(2) For conatant gate opening the shook loss curve

will approximate a symmetrical parabola with its vertex

the point of minimum loas located at the rated condition

of operation (7 Pbull 79)

c Exit Loas

It can be seen from Figure 2 that the exit loss from

the turbine would be v222g if no draft tube were present

The addition of a draft tube permits the gradual reduction

of velocity by an increase in cross sectional area between

the exit of the runner and the exit from the draft tube

The exit loss and the frictional loss encountered in

the draft tube may be placed together in the expression

m va2 (3)Exit Loss ~---2g

For the ideal case of no friction in the draft tube

m is equal to the square of the ratio of the area at exit

from the runner to the area at exit from the draft tube

In an actual turbine installation however friction

will change the value of m (7 p 84-85) to somewhere

between that for the ideal case and a maximum ot 10

In the interest of maintaining a minimum exit loss

the turbine should be designed and operated so the velocity

V2 will be minimum This will occur when the discharge

13

vector is at right angles to the tangent to the runnerbull

ie the angle A2 1e ninety degree bull It ia to be expected

that this condition will be tultilled near the design con~

d1t1ons ot the ~bine

Current design praetiee 1 to have a small component

ot v2 in th$ direction of turbine rotation at rated condibull

tion$ ltS p 938)

For a constant turbine speed the d1seharg or exit

loss is ess nti lly a constant

For a constant gate opening the exit lo s curve is

aptrroximately a symmetrical pa~abola with ita vert x the

point or minimum loss located at a slightly lowe~ speed

th n the turbine rated speed (7 Pbull 79)

Chapter III

PROPOSAL OP ALlERMAlE MFTBO 0 CO TROL-A lz ~ Location 2 Control

Thua tar only practice and theoretical aspects appemiddotrbull

taining to present day turbinea have been d1acuaaed It

haa been presented that control over the ~bine ia ezerbull

oiaed b y manipulation of the wicket gatea located 11101led1bull

ately preceding the runner These gate - upon rotation

modify both the magn1tu4e and the direction ot the entering

velocit7 Moreover it has be n shown that a simultaneous

change in these two variables leads to inefficient operabull

tion by the introduction of shock loss he farther the

point of operation a from the rated conditione the more

aerioua ia the ahock loss encountered

Any attempt to better turbine pertorance at other

than rated conditione and tbne flatten the top ot the

etticieney hill8 must concentrate upon the lessening ot

the ahock loaa It 1a a aumed that 1 provement in the

scroll case gates and runners would lequ1re sueh pertecbull

tion 1n machine work and metal$ as to be prohibitively

expensive

It ie surmised that any move to elblinate eYen parbull

tially the shock loss would require separate control ovel

l$

the flow and gate exit angle Since it is improbable that

d1~ect1on could be controlled at any location other than

where the gatea are situated in current turbines it will

be assumed that guide vanes will be necessary regardlesa or the method used to control the rate of flow

The primary purpose ot th se guide vanes 1s that or control over the direction ot the incoming water They

should be free to rotate in much the same manner as ordibull

nary wicket gates in order to exercise control over th

turbine speed

If the rate ot tlov is to be controlled elsewhere it

must be modified either in the penstock or the draft tube

Devices that could be used are standard valves gates

variable orifices variable venturi sections and associated

flow regulating schemes

Alauming it were decided to locate such a device upbull

stream of the turbine it would be necessary to allow disbull

tance tor the flow picture to become reestablished prior to

entry to the turbine A contused flow making transit of

the turbine passages would only contribute additional loesbull

ea Such a distance allowance would be perbapa 20 to So

diameters (2$ Pbull 119-123) In large penstocka th1a would

repreaent a considerable distance Which from the viewbull

points ot convenience and control would be undesirable

Attempts to ascertain the effect or additional tlov

16

reduc ion at the wicket gatctsmiddot wae ade 1n the lfadraulioe middot

Laboratory of Oregon St middot te College in 1933 (20) Three

d1tterent thode ot reducins the tlow were t~ied

(l) Locking in the cloeed position pairs or wicket

gatea located opposite to eaeh o~er on the -periphery ot

the wheel

(2) Locking adjacent gates in an open position by

inserting blocks of wood between them and

()) Suocess1vely looking adjacent gates in the closed

position

The results indicated a arked reduction in both power

and efficiency when compared to the curves tor normal gate

operation However it was demonstrated that it was poae1bull

ble to ahitt the power and tfieiency curve ill relation to

turbine apeed lbis important feature will be diacussed

later

ihe main conclusion of the investigation was that conbull

trol by the conyent1onal wick t gates was auper1or to other

methode egtt control exercised at the gates the aelvebullbull

It would app$ar that the bebullt location tor flow conshy

trol would be in the draft tube since none of the objecbull

tiona prev1ously mentioned wou~d eziat there

As bas been stated previously the sole object or the

17

18

turbine is to produce power as etfic1ently as possible

The equation tor the power output of a turbine () Pbull 227)

PaWHe HP (4)55o bull bull Assuming the head 1a constant and a g te located in

the draft tube decreases bhe rate ot flow the power eu

only be increased if the etticiency increases

The ettective head Gn the turbine 1s conventionally

d r1ned as the difference between the auma ot the elevashy

tion head pressure head and velocity head at the entrance

to the turbine casing and the tailrace ($ Pbull 872)

lt ie recognized that the theoretical treatment ot

shock loss as given is highly approximate and serves only

to dictate certain trenda For example the area at xit

rom the wicket g tea CfUl be measuPed with some exactness

but there exists no guarantee that the wateP particles will

complet-ely fill the apace oz- will exit at the establiahed

g te angle The same can be said of the exit trom the

runner blades AssUIlptiona were implied which would indishy

cate that all water particles passing a given croea section

ampH traveling at the same velocity in the same direction

the e alone are autt1c1ent to show 11m1tationa in a theoretbull

1eal approach to the problem

Assume a turbine with ordinary wicket gates tor oonbull

trol compared gainst the same turbine with a gate in the

18

draft tttbe tor supplampment1ng control or the rate ot rlow

Let it also be assumed that the two turbines are opershy

ating at the same point It 1s desirable to predict relabull

tive performance of the two turbines 1 this point of

operation is such that edd7 s hook loss ot reasonable proshy

portions is present in the fir t turbine

~ tull erteot of the shock loss will be exper1 need

by- the fir t turbine

lhe second turbine will derive certain advantages 11

the gate in the draft tube is adjusted to reduce the tlov

1n the proper amount Since they vary a the square ot

the veloo1t7bull the lossabull in the aeroll case wiomiddotket gate

and runner passages will decx-ease aetet-r1ng to Figure 2 1

it can be seen that a decreased velocity v1 w-ill reduce the

eddy shock losa

The ent loss in the dJtaft tube of the second turbine

will be the sum ot the tr1ct1onal loss and the velocity

head at ex1t The velocity head dissipated will be greater

due to the closing action or the gate but the reduoed

t~ictional loss which ia a tunction ot the rate of tlow1

will partially balance this

It 1a entirely possible that the net reduction in

losses in the second turbine will lead to a greater ettibull

oiency and more power output than 4eYeloped by the first

turbine

19

In Figure 3 the plot ot power output against turbine

speed for Curv A~ represents the typical family of curvea

tor a reaction turbine Th b st sp ed is the locus ot

points connecting maximum eft1oiency at each gate opening

The operating speed is the coZUJtant turbine apeed which

passes through the point ot maximum efC1ciencr of the turbull

bine The plot of turbine efficiency against power output

for Curve A is also ahown

It the turbine with flow regulation in the dratt tube

oan demonstrate superior power and efficiency at part loads

the effect would be the same as a shifting or the power

curves toward the condition shown fop Curve B 11 Thisbull

illustrates th ultimate case of the uperpoait1on of best

and operating speeds It will be noted that the pet-form~

of the turbine ot Ourve Bu 1a better than that of CUrve

A at part loads because of ita ability to sustain a relabull

tively high etticienoy ovel a Wider range of power output

o Reguireaegts tort Test Velitication

It is desired to deterra1ne the effect on the turbine

performance b) the addition of a gate in the dratt tube

Th step in the teit will bet

(1 To determine the power output and efficiency ot

the turbine tor wicket gate settings above and below rated

conditione for a wide range ot speed

20

CURVEAbull

TURBINE SPSBD TURBID SPEKD

POIBR OOTPOl

Figure 3 - Turbine Performance Curves

21

22

(2 peat (l) with the gate installed in the drat

tube

(3) middot Converting middot all data to a constant head compare the

powere and effioiencies at the same wicket gate setting and

turbin speed tor the two cbullses

If the ddition or the gate indicates an improvement

in power output and efficiency and the powe~ curve shifts

to the right along the turbine apeed scale the advantage

ot draft tube con~ol of the flow will hav been demonshy

strated

Chapter IV

A E9J11pment

ih turbine used in this test is lJ 5 1nch Pelton

reaction turbine with a rated output ot 30 horsepower under

a head of 56 feet at a speed ot 720 reYolutiona per minute

Views of this turbine are hovn in Figures S and 6 The

turbine is installed on a concrete pad located over an open

channel in the Hydraulics Laboratory at Oregon State Colshy

lege The date of manufacture of this turbine was 1915

The water was delivered to the turbine from a sump

reservoir by two pumps operating 1n parallel Each pump 1a

an 8 inch Pelton double suction centrifugal pump witb a

rating of l$00 gallons per minute at a head ot 75 teet with

a speed ot 1175 revolutions per minute Tbe inlet tlange

ot tne turbine is $pprox1mately 18 feet above the center

line of the pump

A direct current generator was coupled to the turbine

to receive tne power d veloped as shown in Figures 4 and 7 The generator is a Spr gue Electrodynamometer rated at SS horsepower with a speed range of 7$0 to l$00 revolut1one

per minute The classification is type LO 26A 2)0 volta

Figure 5 - View of Test Turbine

Figure 6 ~ View of Test Turbine

and 149 amperes lbe generator ti ld was aepar tely

excited using direct current from a motor g n r tor ampt

(l$ p 4~8)

The power output of the generator waa dissipated in

the water rheostat (3 p 488-489) shown in Figures 9 and

10 The galvanized tank contain d water ot variable d pth

on an electrode ot cast iron m aauring 1bull x 1 x 1

In the initial installation of the turbine it was

intended that the power output should be measured with a

Prony brak bull For th purpoa68 or this teat it was decided

that the brake was too instable and the generator was

substituted The platform for raising the generator the

nee asary two teet for alignment was built out of available

material In this case heavy laminated wood blocks reiashy

torced with other timbers were used and bolted through the

concrete deck (11 Pbull 36-$7)

Due to the light concrete deck the lack ot mas in

the platform and the slight misalignment in the flexible

coupling ao e vibration waa encountered It seemed to

ncr aae linearly to a maximum at the speed of bout 750

revolutions per minute Above this speed no vibPation was

noticeable The vibration waa not se~ere and does not

appear to have materially affected the test results

26

B Intrumentat1on ~ eaeur1ng Devices

The pressure head at inlet to the turbine vaa meaave4

bymeane ot two )6 inch waterbullmeroury manometerbull connected

in series as shown in Figure 8

The terminal voltage ot the generator vas meaeured by

a laboratory voltDleter with a range to )00 yolta and callbull

brated to within 15 Yolta

The armature current bull and hence the line current was

measured by a laboratory ammeter with a range to 150 amperea

and callbrated to w1 thin o 7S amperes

Tae rate ot tlow was established by weight and time

meaeurementa The weighing ank has a capacity ot 121 000

poundsJ the weight belng indicated by Toledo direct reading

scales Timing was done with a hand atop watch with clivibull

aion ot 02 second

he ~ater level in the tailrace was dete~1ned by a

hook gauge lhie was read to the nearest 001 toot

The turbine and generator speeds were eaaured by a

hand tachometer The technique of almost cont1nuoua readbull

ings of the speed gave an error ot no more than 5 revolubull

tiona per minute

c Operational Procedure

Atter the water level in the aump was checked to

insure an adequate auppl7 the puapa were primed and

27

Figure 7 - Test Generator and Plattorm

Figure middot8- Instrument Board and Field Rheostat

28

started After venting they were valved for operation 1n

parallel

The motor generator set was started to supply the

field current and the circuit breaker was closed Water

wa added to the water rheostat to the level shown in

Figure 10 ~ field current wae minimized by cutting in

all the f ield resistance in the field rheostat of Figure 8

The l2 inch gate valve shown in Figures 5 and 6 waa

slowly opened and the turbine and generator brought up to

speed The 12 inch gat valve and turbine were vented and

the pumps were checked to insure neither had lost ita prime

lhe water rheostat offers very steady load 1f the

water level is essentially constant and the water temperabull

ture 1a fixed () p 488~89) In order to maintain this

constant temperature it was decided not to circulate the

water in the rheostat but rather to allow the water to

boil thua achieving the desired result A standing wave

was set up on the face ot the electrode by the boiling

action but a atable load was eatablished except at very

low water leYels where th11 agitation led to fluctuationa

in the line current

After putting the turbine and generator on the line

maximum power was dissipated in the rheostat by redueing

the turbine speed to between oSO and Soo revolutions per

minute Salt vas added to the rheoetat wat r to increasemiddot

29

Figure 9 - View of Water Rheostat

Figure 10 - View of Water Rheostat

Separate Field ExcitationFrom Motor-Generator set Compound Water-Mercury

---shy

re Manometer

I Q)

~ 0

~

Book Gauge

Open Channel

I

Slap Reservoir

Figure 11 - Wat~r Flow Diagram and Electrical Layout

31

waiting pe~iod ot perhaps an h~ followed

while the boiling point or the water wbulls reacbe4 During

this ti+ne the manometer was vented end eheoked electrical

measur1ng 1nstlUments were connected end the hook gauge was

adjusted tor elevation

It required about two- houtte tor the generator to reach

its normal operating tempe-ratu~e_ After the water in the

rheostat and generator had reached their operating temperabull

turea it was possible to begin the taking of data

The only vaPiable which was controlled wee the turbineshy

generator speed However the upper l1ut1t of safe line

current was slightly over 100 ampJilPampPes and the eireuit

breaker would open when the current reached lOS ~ere bull

Control was exercised by means ot regulating the water

level and salt 1n the water rheo tat and the res1stsnoe of

the tield rheost t~

The etfeet ot each type ot regulation on the three

variables is shown below

Volta Aaperebull Speed

Inc Dec Inc Dee~ Inc Dec

Wa~e1 Level Inc Dec~ X

X X X X

X

Salt Concentration

Inc Dec X

X X X X

X

field Resistance

Inc Dec

X X

X X

X X

32

Jlot all methods gave the ame amount ot change in a

given variable and a period of experiment and trial led to

the following scheme starting the rune with the lowest

turbine speed the water level was high with a high amount

ot salt and the field resistance was cut completely out

Aa it became necessary to increase the speed tor each

aucceasive run either cutting in t he field resistance

decreasing the salt concentration or lowering the Vater

level would produce the desired result However decreasbull

1ng the salt concentration had to be done Without a net

gain in water which led to a tluahing procedure that was

not particularly good because cold water was introduced

which required time to heat to the boiling point Cutting

1n additional field resistance was a good method but th1a

increased the amperage possibly to the point of opening

the circuit breaker Lowering the water level was aatiashy

factol1 until the level got too low causing the current

fluctuation previously mentioned Actually it turned out

that a combination of lowering the water level and cutting

field resistance in would carry the speed from ita minimum

to 1ts maximum value it the proper choice were made each

time the speed waa to be changed At the conclusion of

each aet of runs at a high speed the water level would be

low and the field resistance high

33

TURBINE

PAD AND DECK

TAILRACE

WATER SURFACamp

CONCRETE

DRAFT TU1B INSERTS

7 5( DRAFr TUBE

FLltJI ARIA

5~ DRAFT TUBE

FLOI ARSA

Figure 12 - Sketch of Draft Tube and Test Inserts

34

Figure 13 - View of Draft Tube Insert

Figure 14 - View of Draft Tube Insert

D c __ ~s_middot hedu_le of

A number was assigned to each run The fi~st number

applies to the draft tube tlow areas

1 bull 100~ flow area or 0~ oonatriction

2 - 7S tlow area or 2$ conatr1ct1on

3 SoC flow area or so~ constriction

The second number refers to the wicket gate openings

9 over gate opening

6 bull intermediate gate opening

4 bull one h lt gate opening

The third number 14entif1ea the location of the particular

1Wl in a set ot rona made at a given dratt tube tlow area

and wicket gate opening

fnua run number 1bull4bull10 would identity this as the

tenth run ot a set made at halt gate with 75 ot the draft

tube t1ow area

Rune w re made tor a g1yen dratt tube condition

Firat tor tull 41-aft tube flow area seta ot rune were

made for the overgate halt gate and intermediate gate

conditione An insert was placed in t he draft tube and

rune based on the same gate conditions were made tor the

7S~ draft tube flow area case The insert was then changed

to allow only $~ draft tube flow area

The inserts are sketched 1n Figure 12 and photographed

ln Flgurea 13 and 14 They oonaisted of circula~ segments

36

or l2 ineh plywood mount 4 on wooden legs 10 inches high

The 1nse7te were placed in position and secured by th use

ot a-clamps on the legs and the outside ot the bottom of

the draft tube The obvious disadvantage to this method

waa the neoeasity tor draining the water from the tailrace

tor a change ot 1naert The advantage vas of course the

simplicity ot design and construction

Chapter V

DATA-A Original Data

The normal data-taking crew consisted or two men

Assuming adjustments having been made to secure a certain

turbine speed (aee section on Operational Procedure) one

man would take semi-continuous speed readings with the hand

tachometer until a state or rotational equilibrium was

reached This could be only a period or two minutes up to

ten or tifteen minutes As soon as steady speed was

assured the data taking would begin The second man went

to the weighing tank Where a minimum ot three weighingamp

were made The requirement was to get three consecutive

readings such that the ditterence between tbe smallest and

largest time did not exceed 04 seconds The time to

collect a given weight ot water was then assumed to be the

arithmetic average of the three times He then went to the

hook gauge determined the hook elevation and then

recorded the data on the data sheets The first man meanshy

while had taken readings of the line voltage line current

and manometers and checked the turbine speed by multiple

readings During the length of the run all values were

38

checked to determine mean values for recording

The minimum length of one run was about five minutes

If one or more measure ants tended to drift during the run

all values wer discarded and a new run began as soon aa

qu111br1um was stabl1shedo

B -0-al_e_u_l_a_t--d Data

The h d on the tu~bine 1 defined by

($)

The maxtmwm velocity V4 was equal to about o8 tampet per

secon4 which makes it a negligible quantity when converted

into velocity head

An engineerbulla level was used to deterine the d1ffePshy

ence 1n elevation between the compound water-mercury manoshy

meter and the hook gauge Using this value the equation

for turbine bead becomes

where z4 is the hook gauge reading

The rate of flow 1 cent

w weight or water collected average time to collect

The inlet velocity v1 vas calculated by dividing the

weight rate or flow by the specific weight of water and the

)9

area ot ~e inlet pipe This was equivalent to dividing

the weight rate of flow by 490 Then the power input to the turbine is equal to

WHpin rri

10 (6)

Also

(P ~ut) Turbine

(P out) + Generator

(P lost) Generator

The power output of the generator is simplJ the

produot ot the terminal voltage and the armature (line)

curPent The power lost in the generator can be subdivided

into copper losses and stray power losses lo evaluate

these cunes based on losses of an identical generator

11leampsured by the Department ot Mechanical Engineering were

used The loss curves are reppoduced in part in Figures

15 and 16

Determination ot generator losses proceeds as tollowau

(1) From Figure 15 detem1ne the vo1tage drop in the

armature circuit using the temperatures of 1220 F and the

meaaured current

(2) The induced voltage is t~e sum of the terminal

voltage and the voltage drop 1n the armature circuit

() Entering the induced voltage and the turbine speed

into Figure 16 the stray power loss can be determined

(4) The copper lose can be evaluated from Figure 1$

using the measured current and the temperatlll-e of 1220 P

40

25 ~------~--------~--------~------~

U) -U) - 20

f-4 ~

-~ -gt 0

0

VOLTAGE DROP

~ - i -

- bullbullbull bull - -middot-middot -+ ~- + -t--+ ~ - ~ middotbull ~-~ middott- -+----- _ -4 middotmiddot- --~-+-t---r~~ ~--+t-t- - ---t-c-++~-ulf--

0 50 75 100

Figure 15 - Curves of Generator Voltage Drop and Copper Loss

41

1200

1000

800

600

800

0

0

~-

middot--~ 1shy --1 + bull l

100

I -

150 200

IIDOOED VOLTAGB (VOLTS)

Figure 16 - Curves of Generator Stray Power Loss

_ j

-bullshy -L---- shy middot -shy

250

- r

42

(5) The generator los os equal the sum of the eopp r

loss and stray power loss

~e efficiency or the turbine is taken as

etticiency u e =P out (8)Pin

~ample pound Determ1n1gg turbine Power Output

The following data are taken trom that ot Run 1-9-1

Line voltage 1040 volts Line current 870 amperesSpeed 355 revolutions per minute

The induced voltage 1a determined as follows

Line voltage 1040

Voltage drop 90 using Figure 15 with line current of 870 amperes and temperature ot 122 degrees)

Induced Toltage 1130 volta

The power output of the turbine is determined as follows

Generator output 90$0 (line voltage z line current)

Oopper loss 7 (using Figure 15 with line current of 870 amperes and temperatUe or 122 degrees)

Stray power lose 470 (using Figure 16 with speed ot 355 revolutions per miDUte and induced voltage or 1130 volts)

Turbine power output 9527 vatta

or turbine power output 1s 12z2 horsepower

43

The conversion of the calculated data to a constant

head is based on the conventional assumption of constant

efficiency regardless of turbine head For a constant head

ot 81 teet a purely arbitrary figure the tollowing relashy

tionships are ass1lJiled to be true

I ____L (9) (i)l72

(10)

For these two values the specific a peed may be combull

putedt

N t Jt VPt (11)8 243

Chapter VI

~RESULTS

A -Pr_e_ae_n_t_a_t_t_o~n g Reaultbull

Graphical presentation ot the results ot this te1t

are given as follows

Figure 17 -Turbine characteristics with 100~ dratt

tuba 1low area

Figure 18 - Turbine characteristics with 7S dratt

tube tlow area

Figure 19 bull Comparison ot power and etticiency at

over gate conditions between 100 and

75~ draft tube flow area

Figure 20 bull COZQparison of power and ettic1ency at

halt gate conditions between 100~ and

7S~ draft tube flow area

Figure 21 bull Comparison of power and etticiency at

over gate condition between 100~ and

So dratt tube tlow area

Figure 22 - Comparison in variation ot apec1t1c

speed between 100 and 75~ dratt tube

tlow area

50

45

20

-bull - 1--shy40

bull J-~ 30

~ ex

~ 20

~~ ~ -)q

I

~ - _

- -

10~ OF DRAFT TUBE FL(Jif AREA

CONSTANT HEAD OF 8l FEST10

POIER OUTPUT EFFICIENCY SPECIFIC SPEED

0 ~--------------_--------~------~------~ 400 600 800 1000 1200 1400

TURBINE SPEED (RPM)

Figure 17 - Turbine Char~cteristics with 100 Draft Tube Flow Area

50

46

-bulllle

~ 7 ~ OF DRAFt TUBE FLOW AREA

0 -~~-rl C05STAMT BEAD OF 81 mET 1J~

POIER OOTPUT ---+- ---o ~_H EFFICIDCY ~ I shy

bull ql SPECIFIC SPEKD - ~ -

bull ~ J 10 L rmiddotr- r- -

bullz- I

~~ 30 ~~--~----~~-

20 ~ ~ middot-shy

26

~~ 25

~0 ~r-----i (

Tbull -bullshy

400 600 800 1000 1200 1400

TURBINE SPEED (R PK )

Figure 18 -Turbine Characteristics with 75 Draft Tube Flow Area

47

EFFICIENCY 60

1-----shy

-~ 50~--~--~~-~middot middot middot middot r~-~----~~~~---4~-r~-~~gtt

II

POWER~ J ~ bull bull

u I

sH

40~------+-------+---- -~~--~~-~~~~

~----~rl 1 bull

I

I

0~--------------~------_------~--------

~ -OVER GATE CONDITION

COIJSTANT HEAD OF 81 FEET

0 o 10~ DRAFt TUBE

_-- _ 7~ DRAFT TUBamp FLON AREA II

10_~-----+--------r-------r----~~

400 600 800 1000 1200 1400

TURBINE SPEED (RPM)

Figure 19 middot - Comparison between 75 and 100 Draft Tube Flow Areas of Power and Efficiency at Over Gate Conshydition

48

t

bull --4 r ~- ~ middot~

70 1-----------+-~~~~~+middot ~ ~~ middot middot -~~--~~--------~~----~-+1

-~-

Atbull bull

lla-

60

amp0

40

20

10

oampOO

t _ - - ~-+- - -~-

l2 GATB COJIDITIOJJ

COJISTABT HJW) OF 81 JBET

o 0 lOQ( DRAFl TUB8 FLOI AREA

e-- - e 75 DRAFT TUBE FLOW AREA

800 1000

- r-

~

TURBIbull SPBIID (RPII)

Figure 20 - Comparison between 75 and 100 Draft Tube Flow Areas of Power and Efficiency at Half Gate Conshydition

49

60

50

-40

bull 30

IIQbull

20

10

0

400

- t - ~

EFFICIENCY

_J bull - bull bull

~ r r middot t -+ shy L -t -

OVER GAD COliDITIOI

CONSTABT BEAD OF 8l FBB

o o 10~ DRAFt TUBE FLOI ADA middot--- 5~ DRAF TUBE FLQPi AREA

600 800 1000 1200

Figure 21 -Comparison between 50~ and 100~ Draft Tube Flow Areas of Power and Efficiency at Ove~ Gate Conshydition

50

25

20

15

10

0

Figure 22

~- T -4 -t- -l --~-

t-~ I

middot --~- t ~---- _ __ _ + --

----~- --r-- --

~-=J-~-=-~ -==~ _ ~- -- ---f---1 - shy

CONSTANT HEAD OF 81 FEBT

o--o 1~ DRAFT TUBE FLltll AREA

75C DRMT TUBK FLCIJ AREAmiddot--middot-middot 600 800 1000

TURBINE SPEED (RPK)

Comparison of Specific Speeds for 75 and 100 Draft Tube Flow Areas

51

B Discussion 2 Result

Consideration of Figures 17 and 18 indicates the

overall eftioi ncy pattern or hill is significantly or

rounded for the 7$~ flow area than for the 100~ flow area

bia implies a greateP efficiency is possible at speeds

leas than or greater than design speed with an insert in

the draft tube However the muilDum efficiency is lemiddotas

Direct comparison at over gate conditions is made in

Figure 19 ~e same general trend is noted tor both the

etticiency and power curves for the 7$~ flow area case

The eurves show higher values at overspeed than do the

correaponding cWvea for the 100 flow area case It ia

not clear whether the curves have been shifted by the dratt

tube constriction or whether the curves simply bulge past

the normal curves at both overspeed and underspeed condishy

tions The power curves apparently peak near the aeme

point bullalthough maximum power is still obtained with the

normal draft tube area

For the comparison at halt gate operation shown in

Figure 20 a general improvement has apparently been made

by restriction of the draft tube flow area At every speed

the etticienoy and the power is greater for the restricted

tlow case The two ett1o1ency curves and two power curvea

are practically parallel throughout the speed range ot

teat

As the flou aroa i e decreased still farther a s1gn1

ticant change appears Reterr1ng to Figllle 211 tor the $0

flow area curves it a obvious that exit losses have

become excessive at the overgate condition because the

efficiency and power are everywhere leas than tor the case

of normal draf t tube area

Earlier it was pointed out t hat 1t the r esult s 1nd1bull

eated an increase in both power and ef tieiency- t hen it

could be assumed tha t the additional los s i ntroduced with

the draft tube insert is less than the diminished losses

due to leas shock losa and water passage losses For the

places where both the efficiency and power have been

increased we can assume that the insert has improved turshy

bine performance

For the places where the power haa been decreased

nothing can be said as to the elimination of ampbock loss

because the new lose present with the drat tube insert has

overshadowed any gains in eftecti Ve head upatJ-eam of the

insert

Near the peak of the efficiency hill howeve~ it may

be pointed out t hat shock loaa ie a minimum with a normal

draft tube and the insert merely adds an additional loss

with the resultant decrease in maximum efficiency tor the

7$~ flow area case

Perhaps the most s1gn1ticant set of eurves is shown aa

53

Figure 22 In this graph values of specific speed tor the

75 and 100~ flow area cases for both over gate and one

halt gate openings are plotted against turbine speed At

every speed and both gate openings the value ot specific

speed for th 75~ flow area case is greater than that for

the 100 t1ow area ease

Since the head is a constant for both situations this

may be interpreted in either of two ways trom equation

(11)

(1) For the same turbine apeed restriction of the

draft tube t1ow area resulted in greater turbine power

(2) For the same power amputput the turbine with 75~

draft tube flow area operated at a greater speed than did

the one with 100 flow area

Since the required diameter of a turbine varies

inversely with the speed the second interpretation could

be stated such that a smaller turbine could be used to

develop the same power output

Whether viewed trom the aspect of increased power

greater speed or reduced size the performance of the turshy

bine with reduced draft tube flow area is superior to that

with the nolmal flow are in the draft tube

The curve of specmiddotific speed versus turbine speed for

the so draft tube flow area case at over gate cond1t1ona

was not included in Figure 22 This curve lies below that

for the 100~ flow area c se at all speeds

In elaboration ot the second interpretation of Figure

22 attention is directed to the relative magnitudes ot

increased apee1f1c speed tor the two gate openings Assumbull

ing that the increase in specific speed implies a shift ot

the power curve to the right along the turbine speed scale

the power curve would be shifted more tor tbe halt gate

opening than tor the over gate opening

It thia trend could be extrapolated to the other gate

openings the tendency can be seen tor the line ot beat

speed to rotate toward the line of the operating speed as

illustrated in FigtU-e ) The advantage of this has already

been discussed

This particular turbine has a low specific speed tor a

reaction turbine Aa the rated value of apecitic apeed tor

reaction turbines increases the line ot beat speed departs

even more radically from the line of operating bullpeed It a

test similar to this were conducted on a reaction turbine

ot gleater specific speed it is pJobable t hat the rotation

ot the line of beat apeed would become more p~onounced

The scheme used in th1a teat had two obvious dr wbull

backs The first was the decision to leave all the wicket

gamiddottes installed tor all conditions ot the draft tube

These gates predominated in control of the tlow The

inserts added to the draft tube merely acted as auxiliary

55

contrGla

The aecond drawback was the choice or device to place

in the draft tube The reasons foll selection of this type

of device have been previously mentioned It is to be

anticipated that adaptation ot dratt tube flow control

would result 1n a better device for an actual turbine

installation Such apparatus might take the form of a

pneumatic bladder or a h7drau11oally operated variable

venturi section in the draft tube It is conceivable that

the gate as used in this test might be adapted also

Chapter VII

OONCLtJSIOfS

From the results of this test the following eonolubull

e1ona aa to the effect ot a variable draft tube flow area

on the performance or a r action turbine may be drawn

(1) The effect ot a variable draft tube tlow area 1a

generally favorable upon the operat1Gn ot a reaction turbull

bine because or the tendency tor the line or beat speed to

rotate toward the line ot operation This resulte in

better performance of the turbine at partbullloads

(2) he etf1o1ency eh111 tor the turbine beeomaa JDore

tlat at the top leading to a smaller max1JilWD effic1enc7

but e reater etticieney at other pointe of operation with

the insertion ot an auxiliary control ror the rate ot tlov

in the draft tube

(3) The power output of the turbine will increase at

over speed over gate conditione as well a at part gate

conditions with the proper amount or draft tube eonatr1cbull

tion or flow

(4) It is possible to eliminate at least partially

eddy type shock loss by tho introduction ot flow control

in the draft tube

BIBLIOGRAPBl

1 Addison Herbert A treatise on applied h-draul1cs New York Wiley 1954 724 Pbull

2 Allen o M and I A Winter middot Co111parative testa on experimental draft tubes Tranaact1ons ot the American ociety ot Civil Engineers 87t893bull970 1924

3 Barrows a E Water power engineering 3d ed ew York McGraw-Bill 1943 791 Pbull

Bovet G A Modern trenda in hydraulic turbine design4middot in Europe Tranaactions of the American Society ot Mechanical Engineera 75975bull993 1953bull

s Oreager William P and Joel D Justin Hydroelectrichandbook 2d ed New York Wiley 19$0 1151 Pbull

6 Daily Jamea w Hydraulic machinery Int Hunter Rouses Engineering hydraulics Hew York Wiley 19$0 p 8$8bull99

Daughertybull Robert L Bydraulie turbines ew Yorkbull7middot MoGrav-Hlll 1920 281 Pbull

8 Daugherty Robert L Inveat1gat1on of tne performance ot a reaction turbine ~anaactiona or the American Society ot Civil Engineers 7811270bull1304 1915

9 Davie L M Model and prototype testa Int Trend in hydraulle turbine practice symposium lranaactions ot the American Society ot Civil Engineers 1o63S3middot368 1941

lfJ Doland James J Hydro power engineering Hew Yorkbull Ronald 1954 209 Pbull

11 Gandy Theodore s and Elmer c Schacht Direct curshyrent motor and generator troubles operation and repair New York McGraw-Bill 1911 293 Pbull

12 Gibaon Arnold H Hydraulics and ita applications5th ed London Constable 1952 813 Pbull

58

13 Button s P Component loases in Kaplan turbinebull and The prediction of efficiency from model tests Probull coedings of the Institution or Mechanical Engineers168743-762 1954

14 Knapp R T~ Oavit t1on mechanics and its relation to the d sign or hydraulic equip ent Proceedings or tne Institution ot Mechanical Engineers 166150bull16) 1952

15 Langsdorf Alexander s Principles of direct curHnt mach1nee 5th ed New York r~cGrawbullH1ll 1940 746 Pbull

16 Lsrner Chester w Characteristica of modern hydraubull lie turbines Trans e~ions of the ~~erican Society ot Civil Engineers 66306-386 1910

17 Linsley Ray K Jr and Jobulleph B Franzin1 Eleshyments of hydraulic enginebullring New York McGrawshyBill 19$5 $82 Pbull

18 Mead Daniel w Hydraulic machinery llev York McGraw-Hill 1933 396 Pbull

19 ead Daniel w Water power engineering New York McGrawbullRill 191S 843 Pbull

20 Mockmore Charles A Part gate operation at water turbines Corvallis Oregon State College Department ot Civil Engineering 1933 11 numb leaves (Unpubshylshed typescript)

21 Mockmore Oharles A Flow characteristics in elbow dratt tubes Transactions of the Amez-ican Society ot Civil Engineers 103402middot464bull 1938

22 Moody L F Hydraulic machinery In c v Davis Handbook ot applied hydraulics New York McGrawshyHlll 1942 1082 Pbull

2) Ptau At-nold Hydrbullulie turbine handbook ld ed Milwaukee AllisbullOhalmers ManufactUIing Company 1948 70 Pbull

RheingalUI w J Recent developments in Francis turshybines Mechanical Engineering 74189-196 1952

25 Russell George E Hydraulica 5th ed New York Henry Holt 1942 466 Pbull

26 Safford A and E P- Hamilton American mixed tlow turbine and ita setting Tranampactions or the Amerieal Society of Civil Engineers 851237bull1)56 1922

27 bull Spannhake W1lhe1Dh Problems or modern pump and tur b1ne design Transactions of the American Society of Mechanical Engineers 56e22$-248 1934bull

28 Sutherlandraquo R A Better ethod or representing and middot tudying water turbine performance ~ansaetions ot thmiddote American Society of Mechanical Engineers 68t675bull 686 1946

29 Teats ot five models or draft tubes tor turbines Engineering News-Record Pbull 182-184 Aug 2 1923

30 White w M American hydztaulic turbines Mechanical Engineering S2t390bull39S 1930bull

31 White w M lhe hydraucGne rega1ner1 its developmentand appl1eat1ons 1n hydroelectric plants Meohanlobulll Engineering 43t37Sbull380 1921 middot

32 Winter I A Economic principlebull in designbull Int Trend in hydraulic urbin practice bull a ampoeiumTranaaot1ona ot the American Society ot Civil Engineerslo6332bull3S2 1941

33 Wiel1cenua G F Fluid mechan1ca or turbo-machineryNev York McGraw-Hill 1947 613 Pbull

APPENDICES

c

Appendix A

NOATIOB

A Angle between the absolute velocity vector and the tangent to the rwmer Subscripts 1 and 2 refel to entrance and exit ot the runner blade

B Angle between the relative 1elooity vector and the tangent to the rwmer Subscripta 1 and 2 refer to entrance and ezit or the runner blade

Angle between the tangent to the runner blade tip and the tangent to the runnel- Subscripts 1 and 2 reter to entrance and exit of the rt1rmer bladebull

Blade angle-gate opening conetant defined by equation (1)

e 09erall efficiency

g Gravitational acceleration assumed constant at 322 teet per second per second bull

H Turbine head detined by equation ($)

m Exit loss coeft1e1ent

Turbine speed expressed in revolutions per minute

Turbine speed under a constant head of 81 teet

specitic apeed of the turbine under a constant head ot 81 teet

p Power output in horsepower ot the tvbine

Power output of the turbine Ulder a constant head ot Sl teet

Pl- Pressure head at entrance to the tUlb1new

l1 Peripheral velocity ot the runneP Subacr1pta 1 and 2 refer to entrance and exit ot the JUnllampr blade

62

v Relative velocity reaulting trom the combination ot the absolute water velocity V and the runner periphshyeral velocity u Subscripts 1 and 2 refer to entrance and exit ot the runner blade

v] Relative velocity vector necessary to produce a tanbull gential entry into the runner blades

V Absolute water velocity Subscripts l and 2 refer to entrano and exit ot the runner blade

v2 Velocity head Subscripts 1 and 4 reter to the ~8 entrance to the turbine and the tail~ace wate~

w Unit weight ot water assumed constant at 624 pounda per cubic toot

V Weight rate ot flow in pounds per aeooncl

XX Velocity component ot ahook See Figule 2

Z Elevation head Subscripts 1 and 4 reter to entrance to the turbine and the taibace water surfacebull

Appendix B ORIGINAL DATA-Run

lfwnber

0-4-1 0-4-2 0-4-3 o-4-4 o-4-S o-4-6 0-4-7 0-4-8 0-4-9o-4-lo o-4-11 o-4-12 0-4-13

o-6-1 o-6-2 06-3 o-6-4o-6middotS o-6-6 o-6-7 o-6-8 0-6-9 o--6-lo o-6-11

Speed

rmiddot2middotbullmiddot(1)

336 38$ 451 S$9 620 669 6lt)$ 120 787 860 932

102imiddot109 bull

352 355 443middot 543middot 620 654AJs32

911 1001 1111

~essure Head rt (2)

410 410 416 426 431 43-7 439 44-9 452 467 482 soo $1 bull $

350 351 35middot7 )66 37-9 37-9 392 41 bull 3 43middot3 460 489

Elevation Bead

fjj $7 $7 $7 $7 $7 $7 51 57 5-15858 $8 58 56 56 $6565656 51 575As5a

Velocit Head

flj 07 07 07 06 06 06 06 os 05 os0404 03

09 09 oa o8 o8 os 07 07 06 o~o

Total Head rt ($)

47middot4 4A44 o 489 49-4 soo $02 $11 $14 $29 5imiddot45 2 576

41 bull $ 416 421 430 44middot3 44middot3 456 47-7 496 523551

Plow

lbtjec

326 324middot317 311 306 30029middot28 middotmiddot middot 386 275middot260 240 218

359 36~35 bull 349 345middot 339 330 318 300 273 240

Line Potential

vyqjbull 1060 1220 ~-0o 1920 2150 2000 2$60 2000 1940 18)015io11 o

1000 1100 139bull5 1760 1925 16$0 1620 1610 1540 1330 870

Line Current

amlscs 960 900 830 740 730655 70bull 0 530 660 600 5imiddot54 6 )60

982 930 860 780 ~3-545

79-5 74-5 670 560 370

P

Appendix B ORIGINAL DATA (Continued)

Run Number

Speed

Pbulltmiddotbullmiddot )

leasure Head ft(2

Elevation Head tt(J)

Velocity He-dfmiddotj

Total Bead tt($

Flow

lbstsec( )

Line Potential vo~ta( )

Line Current

amjs (sect

0bulllt)-1 0-9-2

3ll6 398

28o ~~1

$6 56

1o 10

346 347

390 365

1ooo 1190

aao 835

0-9-3 0-9-4 o-9-S

472 565 632

292 305 312

$6 s6 56

10 o9 o9

)$8 J7~o 37~7

381376 37o

1)6614oo 141o

820 ass ass o-9-6 0-9-7 0-9-8 o-9-9 0middot9-10

680 120 762 844 920

)24337346 366 390

56 $6 56 57 $7

09 os o8 oa 07

)89401 410 431454

367~ 357348 34o 322

1400 1J6o l36o 1310 1170

843 820 7957So 67~0

0-9-ll 0-912

1001 1100

41 bull 7 45-3

s 7 6~0

06 os 480 $18

299 268

980 65$

560 36~5

1-4-1 1-4-21-4-l1-4shy1-4-5 1-4-6 l-4-7 1 4-8 1-4-9 1-4-10 1middot4-ll 1-4bull12

354middot452 562 62q 674shy102 752 760- 863 932

1022 1100-

)82389 4014oa 416 41--7 423 428 44-2 45-7 486 49-2

51S757 51 5-7 5middot15zs sa $8 58 59

07 07 06 06 06 06 06 os o bull o 04 o J

446 45-)46middot4 471 ti7-9480 q86 491505 $19 548 55-4

)28 320 311 306 300 295 291 286 269 2582iimiddot21 bull

1080 14Lo 1550 153-5 1470 141-0 1385 1310 1310 1230 1120 855

970855 875 91-0 94~0 975 966 995 860 77-S 610 4fo

0 ~

Appendix B ORIGINAL DATA (Contirmed)-Run Speed Pressure Elevation Velocity Total Flow Line Line

Number Head Head Head had Potential Current rtjjmbull t~ bttec vyfs am~a12) ( ) ti fli 8

1-6-l $6 33$ $6 0bull9 400 364 1100 93 0 1-6-2 41 34laquo2 $6 oa 406 JS7middot iios a5s l-6-3 500 3~0 5bull6 os 356 1 1 o aos 41middot~1-6~4 35bull4 5-6 oa 41middot 352 16~0 82 0 5~1-6-5 5 bull 36_2 Sbull6 08 42bull6 349middot 161 ~ 0 86~0 1-6-6 622 366 $6 oe 43bull0 345middot 158 0 88~$ 16-A 649bull 37bull1 56 os 43-S 342middot 1570 895 1~- 386 57 07 46-0 192 ) 125A44 333middot 1-6-9 3) 404 5middot1 07 468 317 1620 675 1610 911 42-4 5-7 o6 48-7 298 168 0 61 0 1-6-11 999 451 56 os Sl ll 276 ~2-0 530 1-612 1115 485 58 04 54middot7 238 90 )3 0

1middot9-l 355 279 56 10 )45 385 1040 870 1-9-2 399 28J $6 10 )49 38$ 1140 86 5 l-9-3 ~ ao 291 56 ~0 35middot1 J8J_ JJ6o 815 1bull9-4 579 303 56 09 )68 375middot J4JO 830 l-9bullS 40- 313 )6 09 31middot8 370- 1460 82~0 1-9bull6 679 2) 56 09 3 bull8 364middot 1670 710 l-9-7 682 319 56 o9 384 ) 62 1460 79 5 l-9-8 724 33middot5 56 o8 399 3$6 bull 1480 76 -5 1-9-9 762 34middot3 $6 0 bull 8 407 )48 14910 13middotS 1-9-10 833middot )60 5middot7 os 42$ 339 144$ 686 1-9-ll 926 39middot1 5-7 07 455 318 1290 600 1-9-12 1000 41middot3 0-6 476 298 1115 510$ ~ 1middot9-13 1105 452 s o4 $14 2$6 710 )10

~

Appendix Bt ORIGDIAL J (Continued)

Run Speed Pressure Elevation Velocity Total Plow Line Line Number Head ltead Head jlamp$d P()ten~ibulll Current

r~~~m ft ft lbs~seo voltattj rgj twimiddot t 1 t2gt lt3 ou t ( rt

2-9-1 384 289 S 6 10 35 5 1400 1170 810 2-9-2 443middot 29$ $6 ltimiddot9 360 379middot 11(0 87$ 2-9-J 536 30bull 3 sc 09 )68 374middot 1)40 84 bull) 2-9-4 571 306 $6 09 3~1 372 120bull 0 955 2-9-5 623 316 S6 09 J l )6S UJSo 77$ 2bull9-6 669 327 S6 09 )92 )61 1240 905 2-9bull7 712 )39 56 os 40-3 351 12(0 86 bull0 2-9-8 ~5$~ J48 56 oa 412 348 1290 81 bull ) 2-9-9 04 )63 56 oa 42-7 339 12ltJO 76$ 2middotmiddot9-10 8$2 376 5middot1 07 440 33~- ~ o 710 2-9-11 955 394 5-1 o6 457 300 1100 506 2middot9-12 1000 421 $7 06 48middoti 295 1020 $18 2-9bull13 110~ 463 56 05 $2 267 620 3~0

oshy0

Appendix Gt CALCULATED DAgA

Turbine Run Generator Generator Turbine Turbine Efficiency Turbine Turbine Specit1c

Number OutputKWlt21

Loa~Jes KWlol

Outut K bull (H)

Input RP 12)

middot Percentlt13gt

Speed r~Jmiddot(

0ltput HP ~1

Speed r-m

( 6) middot

o-4-1 0middot4-2 0-4-3 0-4-4 0-4-5 0-4-6 O-qmiddot7o-4-8o-4-9 0-4bull10 0-4-11 o-4-12

1018 1o9a 1220 1)62J40214oa1J4oo 1357 1320 1164 997 718

046 o59 071 092 096 1071oo 134 104 100 109 107

14261sso 17)01948 2008 20322011 1999 19 09 1708 14-84 11o6

281279 27-7 276 215 273271 268 268 26h 258 24-5

soa 555 62$ 705 7)1145 742 74-6714645 51s 45-1

440 sos 585 720 195 sso sao 9$$ 985

1065 1135middot 1230

318 357 319 416 422 419412 39middot9 378 324 260 191

102 12bull4 148 191 21bull 3 22o 233 249 24924middot9 238 221

0-4middot13 418 104 699 228 306 1300 117 18)

o-6-1 982 045 1376 271 $08 496 376 124 o-6-2 o-6-3 G-6-4o-6-5 0-6-6

1023 1200 13 73 J415 139h

051 0middot66 oaa ()bull 96 088

14-39 1696 1958 2026 1986

276 27middot4 273 278 274

$20 61 8 717 7)0726

q95615745 8)5685

390 ll5middot3 sos soo 490

127 170 218 243 2$$

o-6-7 o-6-8 o-6-9o-6-lo

1288 1199 1032 7-45

o9o 094 09$ 096

1846 1733 1511 1128

274 276 271 260

67S 629559 43middot4

980 1085 1165 1245shy

436 )83316 21bull 7

266 276 270 239

0-6-11 322 1oo 566 2141 2JS 1350 101 177 0 --4

Appendix C CALCULATED DAlA ( Continued)-Run

Number Generator Generator

Out2ut Losaes xw LW- 12gt (lO)

Turbine Out2ut

ltPlJ

Turbine Inat lfP Jig)

Etpound1e1ency

PireentDl

Turbine Sed x-~m( 1

Turbine OutEut RPJl)

Turbine Specific

SeeedrIbullntbull

( 6)

o-9middot1 0-9-2 0-9-3 o-lt)-4 09-$ 0bull9-6 0-9-7 0-9-8 0-9-9 0-9-10 o-9-11 0-9-12

aao 994

111$ 1197 1206 1180 11)21081 982 784 5-49 2)9

0middot45oss o6$ 070 07$ 0-77 (l77 or~ o s06o 8 096

123~ 1402 1$80 1698 17bulllS 168$ 16bull18 ~middot5430 1151 a~J4 9

24middotgt24middot3248 25~25 260 260 259 267 266 26middot1 2S2

sos 577 63-7 671 676 650 621 60036J4

327 178

$) 610AlO 3$

92S 980

102$ 1070 1157middot 1230 1300 137Smiddot

44middot4 soo 523 ssomiddot 540so6 46-5 432 368 274 18~8

J46 176 21-1 255 2802s_A 28 289 288 265 231 168

1-4-1 1-4middot2 1-4-3 1-4-4 1-4-5 1-4-6 1-4-7 1-J-8 1-4~9 1-4-10 1-4-11 1-4-12

10bull48 1231 13-S6 1397 1)821375 1))8 1303 1127 953 683) 51

048 067 o7A07 0 bull79 oa1 oss o bullao osa 0lt)0 096 099

J468 1740 1921 1978 1958 19$1 1911 lSSi162 1)98 1045

603

266 264 262 262 261 2512$7 2$6 24middot7 24-3 233 217

551 660 13middot3155 75-6 7~-97 middot4 72$ 67 51middotJ 44middot9 21middot1

475 605 A4220

875middot 910 970_

1000 1090bull 1166 1243 1330

5816

44middot444middot5 430 427 412 392 329 273 188 l0-7

117 101 204 22$ 2)7245 2562sa 257251 222 179

a-C))

Appendix Ct CALCULATED -DATA ( Ocntinued)

1-6middot1 1023 o$2 14-41 26S 505 41~6 26~

54middot5 13middot3l-6-2 1201 067 1boo 625 47-9 17shy~middot41-6bull3 1296 oA9 1 middot43 26 9 700 so5 20bull 4 l-6-4 l3j5 o 0 19~09 268 71bull3 A5o 514 222 1-6-5 1) 5 o81 19(gt4 271 725 51-5 238 l-66 1398 081 198) 27-0 736 8 S13 252~-middot l-6j 1405 083 199i 211 733 885 $middot06 2$9 l-6 13middot9~ 103 2amp 0 279 71 8 985~ 467 ~-69 1228 1 bull 02 17-SS 270 661 109$ 407 ~3~ l-6bull10 1025 100 lSll 26i 573 1175middot 27~S32middot~l-ampu 153 1-00 llft3 26 444 1270 22 24bull8 1bull6-12 294 100 52a 231 22 3 1360 95 172

1-9bull1 904 048 1275 2J4Z $28 S4$ 459 1$2 1-92 98$ oss 13-92 24middot4 57-0 6JO 49bull1 176 1-9middot3 1110 066 1$76 24middot9 63middot4 I2o 536 21-7 l--9-4 1187 072 1685 251 66$ 5 $$ bull 0 261 1middot9-5 llltJ7 1710 25middot4 67-3 93$ 536 28~20-671middot9-6 1186 o 8 1708 25-7 67) 980 $15 2691-9- 1161 oBo 1660 2$middot3 6$6 990 508 29-1 l~- ll-32 oB) 16sect0 2$8 632 1030 471 291 1-9bull9 109$ oa5 2$7 614 1075 29S~middot 0 4imiddot41-9-10 9~91 oas 262 S$1 1150~ 3 o 292 1-9-11 o9o u57 12JiO 21gt 26-77middot74

-45 26sect ~middot91-912 $69 091 sas 25 middot3 1)0$ 196 2J-8 1-9-1) 220 098 426 2)9 178 1390middot 84 16 6

0 0

Appendx C CALCULATED DATA (Continued)

Turbine Run Generator Generator lurbine Turbine Eft1e1eney Turbine lurbine Spee1f1c

Number Output Losses Outit Input Speed Output SPed middot k_-V KW R _ H_bull_P Percent r Thm HP rpm_ (9) tlo) 11) middot (12 _) (lJI ( ) (1$ (14)

2-9-1 9--46 055 1)62 258 528 580 164 2-9-2 1024 056 248 58 4 665 4 9 191iimiddot48 4~middot0 2-9-3 1132 067 05 2$0 641 795 52q 237 2-9-4 1148 065 1027 2$1 -~8 845 525 252 2-9-5 11 77 oso 16-83 253 6 910~ 522 270 2-9 6 1122 071 1600 251 622 960 47-5 2722-9-A 1092 015 1562 257 608 1010 445 2z12bull9- 1052 079 1514 261 580 1060 41middot7 2 2 2middot9-9 986 o82 ]429 26) 542 1105 372 277 2-9-10 915 086 1340 268 500 1160 334 27-6 2-9-11 638 087 972 254 )81 1270~ 229 250 2-9-12 )28 090 828 259 )19 1295 179 226 2-9-13 192 094 383 2$ 6 150 1370 7 3 152

-3 0

Page 10: The Effect of A Variable Draft Tube Flow Area on the

Figure 1

lhe terms of high low small and so tomiddotrth are only

relative in sense A turbinebulls class1f1 eat1on is depenfent

upon its hoad rate of diacharge and speed of rot tion A

useful index tor turbine comparison (5 Pbull 825) is termed

specific speed and this ia a function of the rated ipeed

power output and head or the turbine The common range in

values ot speoitic speed ($ Pbull 826 ) tor each type ot tlirshy

bine is

Impulse J to SS tor one nozzle)Reaction bull 22 to 80 Propeller - 85 to 170

The development of t he reaction turbine began in the

early part or the nineteenth century (26 Pbull 1217bull1)6)

The trst efficient inward tlow turbine was de igned by

James B Francis an American in 1649bull For many years

turbine design was a matter of cutbullandbulltry in America an4

pure mathematical analysis 1n Europe It was not until the

two schools began exchanging ideas in the l$tter halt ot

the n1neteenth century that pronounced advancement was made

in the field

ObTioual7 the primary pux-pose ot any turbine inatallabull

t1on is t he production of power Added to this is the

restriction that the production or power must necessarily

be a controlled process An example of this is where the

turbine is direct-connected to an electric generator which

4

Figure 1 - 135 Inch Reaction Turbine

5

must operate at a constant speed or rotation even though _

the power demand ohangos In thiamp case the turbine nuet

be eap~able or producing a range of power output yet menshy

ta1n e eonetant speed

Speed regulation of the turbine iv accomplished by

means ot a governor (23 Pbull 24bull3-7) bull The contr-ol or regulashy

tion 1s indirect that i s the governor actually exereiaabull

control over the water in order to JJaintain e given speed

Co-ntrol over- the turbine end bence its speed and

power is the function ot a ring of movable wicket gates

located just upsttteam of the turbine runner These w1eket

gates 1n the process of opening and closing upon eeeh

0~1ar in a rotational manner actually control the amount

velocity and direction of tne water passing throu~~ them

C Draft Tubes

It has been found that the effeetive head on a reae

1l1on middotturbine is increased with the addi timiddoton of a draft tube

(3 Pbull 256bull264) Tne draft tube does thin by~

(1) Making a greater presaure d~op across the turbine

possible by the creation of a negative pressure at the

discharge or the runner and

2) DeoreaGing the k1net1e energy lost by increasing

the eross sectional area at exit

he draft tube permits the turbine runner to be

6

located above the tail race water surface without the

sacrifice of head However cavitation will cause pitting

of the turbine if the difference in elevation is too great

A common maximum elevation difference is 19 feet although

this figure is quite subject to modification between difshy

ferent installations (3 p middot 264-266)

There are many different types or draft tubes in use

today the choice or type being largely a matter or

economics (2$ p 368-370) A very common type particushy

larly among the smaller units is vertical with flaring

sides However the angle of flare is limited by the possishy

bility of separation of the flow from the sides In order

to achieve a certain discharge area the length of the tube

may be such as to require a great deal of excavation In

oases or this sort the cost of this excavation must be

balanced against a more elaborate design that does not

require as much excavation Other draft tubes in use

include the elbow hydracone and spreader types

Despite the differences found in construction and

design the draft tube must accomplish the desired objecshy

tives while offering a good hydraulic geometry to the flow

passing through it An inefficient draft tube defeats its

own purpose

Ohapter II

DISCUSSION ~ TURBINE LOSSES

A General

lhe head that 1a actually utilized by the turbine 1a

less than the effective bead as defined by equation ($) by

the amount that 1a lost due to mechanical and hydraulic

reasons

Mechanical loaaea are a function or the turbine 8p$ed

fhis ia not a lineaz- function but varies eomewhere between

N and N2 (3- Pbull 224)

Hydraulic losses encounteled in turbines ma- be subshy

divided aa to the location or occurrence (3 p 225-227) aa

fOllOW$S

(1) Penstock and scroll case

(2) Wicket gates

(3) Between wicket gates and turbine runner

(4) Runner passages

(5) Runner exit into draft tube

(6) Draft tube and

(7) At exit from the draft tube

The flow in the penstock scroll case wicket gates

runner passages and draft tube may be envisioned as

examples of flew in conventional pipes elbows and convergbull

1ng passages If this comparison may be made it could be

assumed that the losses encountered in these locations

would be proportional to vn ~ value ot N is normally2g

aesU111ed to be 2

he losses encountered between the wicket gates an4

the turbine runner and exit lossos are special cases which

will be discussed separately

B Shock toes_

The flow betwe n the wicket gat outlet and the runner

blade entrance is or particular 1nt rest because no direct

comparison vith common flow situations is obvious

Conaider the vector diagram (7 Pbull 7576) in Figure 2

The veetoo v1 is the absolute entering velocity of the

water and is fixed in magnitude and direction by the setbull

ting or the wicket gates The vector l11 1e the peripheztal

velocity of the runnel which tol any given turbine 1e

dependent only upon the turbine rotational speed The

combination of these two vectors ylelda the third vector

v1 which is the relative entering velocity ot the water

nere is only one setting ot the wicket gates for a

given turbine a peed that will produce an angle B1 which

coincides with the blade angle B1bull At other gate settings

the vector v1 will rotate and change in magnitude in such a

9

t ehion that B1 will beoome either greater or 1 sa than B1bull Th1 give rise to tbe phenomenon term d shock loasft

If B1 1a greater than B1 the relative ent ring veloebull

ityt v1 will have a compon~nt opposing the forward motion

of the runner The shock loss could be typified bullbull that

occasioned by direct impact or the water 0n the blade- If

E1 is lese than a] the vector l will overshoot the blade

and the flow will tend to eddy around the forward portion

or the blade tip

The shock loss can then be either due to impact or

eddying flow Since the area norm 1 to the radius at outlampt

of the w1eket gftee is essentially equ 1 to the area normnl

to the rad1u~ at the inlet to the turbine runner the combull

ponents ot vl and vl perpendicular to ul will b approxishy

mately equal This leads to the conclusion that xxbull ~epresenting the shock vector 1 parallel to Ulbull

For either the impact or eddy case the trigonometric

law of $1nee leads tot

XX

bull ul - sin (Bi-Al) vl eln Bi

It it 1a assumed that the energy lost in the shock 1a

the Telocity head ot the shock component XX then

10

VELOCITY VECTOR DIAGIWI

TYPES OF SHOCK LOSS

xbull X

IMPACT BDDJ

XX 1a Teloc1t7 caponent ot shock

Figure 2 - ~bine Runner Vector Diagram$ and Shock Loss Diagrams

11

2 shock loss (XX gt2g

C =sin (BimiddotAl)Let (1)sin Bi

(UlmiddotCV1)2Then shock loabull (2)- 2g

For a given gate opening C ia a constant ranging

from about 14 to 10 For a well designed wheel it is to middot

be expected that C would be approximately equal to U1V1

at rated conditions ie at point of maximum efficiency

This point will occur in the neighborhood of 3~ to 78

gate opening for moat turbines For overgate conditions

the angle A1 becomes larger so the value of C would

decrease For gate openings below rated conditions t he

angle A1 decreases and C would decrease One could expect

a fairly uniform decrease in t he value of C as the gate is

closed from t he overgate position

The velocity v1 is approximately constant for any

turbine speed since the area and rate of flow both decrease

fairly uniformly However for a given gate opening the

velocity V1 will decrease with increased turbine speed

From the foregoing comments and equation (2) the

following trends can be established

(1) For constant turbine speed the shook loss curve

will be close to parabolic in shape concave upward and

have its maximum near t he point of complete gate closure

--

12

and its minimum near the rated gate position

(2) For conatant gate opening the shook loss curve

will approximate a symmetrical parabola with its vertex

the point of minimum loas located at the rated condition

of operation (7 Pbull 79)

c Exit Loas

It can be seen from Figure 2 that the exit loss from

the turbine would be v222g if no draft tube were present

The addition of a draft tube permits the gradual reduction

of velocity by an increase in cross sectional area between

the exit of the runner and the exit from the draft tube

The exit loss and the frictional loss encountered in

the draft tube may be placed together in the expression

m va2 (3)Exit Loss ~---2g

For the ideal case of no friction in the draft tube

m is equal to the square of the ratio of the area at exit

from the runner to the area at exit from the draft tube

In an actual turbine installation however friction

will change the value of m (7 p 84-85) to somewhere

between that for the ideal case and a maximum ot 10

In the interest of maintaining a minimum exit loss

the turbine should be designed and operated so the velocity

V2 will be minimum This will occur when the discharge

13

vector is at right angles to the tangent to the runnerbull

ie the angle A2 1e ninety degree bull It ia to be expected

that this condition will be tultilled near the design con~

d1t1ons ot the ~bine

Current design praetiee 1 to have a small component

ot v2 in th$ direction of turbine rotation at rated condibull

tion$ ltS p 938)

For a constant turbine speed the d1seharg or exit

loss is ess nti lly a constant

For a constant gate opening the exit lo s curve is

aptrroximately a symmetrical pa~abola with ita vert x the

point or minimum loss located at a slightly lowe~ speed

th n the turbine rated speed (7 Pbull 79)

Chapter III

PROPOSAL OP ALlERMAlE MFTBO 0 CO TROL-A lz ~ Location 2 Control

Thua tar only practice and theoretical aspects appemiddotrbull

taining to present day turbinea have been d1acuaaed It

haa been presented that control over the ~bine ia ezerbull

oiaed b y manipulation of the wicket gatea located 11101led1bull

ately preceding the runner These gate - upon rotation

modify both the magn1tu4e and the direction ot the entering

velocit7 Moreover it has be n shown that a simultaneous

change in these two variables leads to inefficient operabull

tion by the introduction of shock loss he farther the

point of operation a from the rated conditione the more

aerioua ia the ahock loss encountered

Any attempt to better turbine pertorance at other

than rated conditione and tbne flatten the top ot the

etticieney hill8 must concentrate upon the lessening ot

the ahock loaa It 1a a aumed that 1 provement in the

scroll case gates and runners would lequ1re sueh pertecbull

tion 1n machine work and metal$ as to be prohibitively

expensive

It ie surmised that any move to elblinate eYen parbull

tially the shock loss would require separate control ovel

l$

the flow and gate exit angle Since it is improbable that

d1~ect1on could be controlled at any location other than

where the gatea are situated in current turbines it will

be assumed that guide vanes will be necessary regardlesa or the method used to control the rate of flow

The primary purpose ot th se guide vanes 1s that or control over the direction ot the incoming water They

should be free to rotate in much the same manner as ordibull

nary wicket gates in order to exercise control over th

turbine speed

If the rate ot tlov is to be controlled elsewhere it

must be modified either in the penstock or the draft tube

Devices that could be used are standard valves gates

variable orifices variable venturi sections and associated

flow regulating schemes

Alauming it were decided to locate such a device upbull

stream of the turbine it would be necessary to allow disbull

tance tor the flow picture to become reestablished prior to

entry to the turbine A contused flow making transit of

the turbine passages would only contribute additional loesbull

ea Such a distance allowance would be perbapa 20 to So

diameters (2$ Pbull 119-123) In large penstocka th1a would

repreaent a considerable distance Which from the viewbull

points ot convenience and control would be undesirable

Attempts to ascertain the effect or additional tlov

16

reduc ion at the wicket gatctsmiddot wae ade 1n the lfadraulioe middot

Laboratory of Oregon St middot te College in 1933 (20) Three

d1tterent thode ot reducins the tlow were t~ied

(l) Locking in the cloeed position pairs or wicket

gatea located opposite to eaeh o~er on the -periphery ot

the wheel

(2) Locking adjacent gates in an open position by

inserting blocks of wood between them and

()) Suocess1vely looking adjacent gates in the closed

position

The results indicated a arked reduction in both power

and efficiency when compared to the curves tor normal gate

operation However it was demonstrated that it was poae1bull

ble to ahitt the power and tfieiency curve ill relation to

turbine apeed lbis important feature will be diacussed

later

ihe main conclusion of the investigation was that conbull

trol by the conyent1onal wick t gates was auper1or to other

methode egtt control exercised at the gates the aelvebullbull

It would app$ar that the bebullt location tor flow conshy

trol would be in the draft tube since none of the objecbull

tiona prev1ously mentioned wou~d eziat there

As bas been stated previously the sole object or the

17

18

turbine is to produce power as etfic1ently as possible

The equation tor the power output of a turbine () Pbull 227)

PaWHe HP (4)55o bull bull Assuming the head 1a constant and a g te located in

the draft tube decreases bhe rate ot flow the power eu

only be increased if the etticiency increases

The ettective head Gn the turbine 1s conventionally

d r1ned as the difference between the auma ot the elevashy

tion head pressure head and velocity head at the entrance

to the turbine casing and the tailrace ($ Pbull 872)

lt ie recognized that the theoretical treatment ot

shock loss as given is highly approximate and serves only

to dictate certain trenda For example the area at xit

rom the wicket g tea CfUl be measuPed with some exactness

but there exists no guarantee that the wateP particles will

complet-ely fill the apace oz- will exit at the establiahed

g te angle The same can be said of the exit trom the

runner blades AssUIlptiona were implied which would indishy

cate that all water particles passing a given croea section

ampH traveling at the same velocity in the same direction

the e alone are autt1c1ent to show 11m1tationa in a theoretbull

1eal approach to the problem

Assume a turbine with ordinary wicket gates tor oonbull

trol compared gainst the same turbine with a gate in the

18

draft tttbe tor supplampment1ng control or the rate ot rlow

Let it also be assumed that the two turbines are opershy

ating at the same point It 1s desirable to predict relabull

tive performance of the two turbines 1 this point of

operation is such that edd7 s hook loss ot reasonable proshy

portions is present in the fir t turbine

~ tull erteot of the shock loss will be exper1 need

by- the fir t turbine

lhe second turbine will derive certain advantages 11

the gate in the draft tube is adjusted to reduce the tlov

1n the proper amount Since they vary a the square ot

the veloo1t7bull the lossabull in the aeroll case wiomiddotket gate

and runner passages will decx-ease aetet-r1ng to Figure 2 1

it can be seen that a decreased velocity v1 w-ill reduce the

eddy shock losa

The ent loss in the dJtaft tube of the second turbine

will be the sum ot the tr1ct1onal loss and the velocity

head at ex1t The velocity head dissipated will be greater

due to the closing action or the gate but the reduoed

t~ictional loss which ia a tunction ot the rate of tlow1

will partially balance this

It 1a entirely possible that the net reduction in

losses in the second turbine will lead to a greater ettibull

oiency and more power output than 4eYeloped by the first

turbine

19

In Figure 3 the plot ot power output against turbine

speed for Curv A~ represents the typical family of curvea

tor a reaction turbine Th b st sp ed is the locus ot

points connecting maximum eft1oiency at each gate opening

The operating speed is the coZUJtant turbine apeed which

passes through the point ot maximum efC1ciencr of the turbull

bine The plot of turbine efficiency against power output

for Curve A is also ahown

It the turbine with flow regulation in the dratt tube

oan demonstrate superior power and efficiency at part loads

the effect would be the same as a shifting or the power

curves toward the condition shown fop Curve B 11 Thisbull

illustrates th ultimate case of the uperpoait1on of best

and operating speeds It will be noted that the pet-form~

of the turbine ot Ourve Bu 1a better than that of CUrve

A at part loads because of ita ability to sustain a relabull

tively high etticienoy ovel a Wider range of power output

o Reguireaegts tort Test Velitication

It is desired to deterra1ne the effect on the turbine

performance b) the addition of a gate in the dratt tube

Th step in the teit will bet

(1 To determine the power output and efficiency ot

the turbine tor wicket gate settings above and below rated

conditione for a wide range ot speed

20

CURVEAbull

TURBINE SPSBD TURBID SPEKD

POIBR OOTPOl

Figure 3 - Turbine Performance Curves

21

22

(2 peat (l) with the gate installed in the drat

tube

(3) middot Converting middot all data to a constant head compare the

powere and effioiencies at the same wicket gate setting and

turbin speed tor the two cbullses

If the ddition or the gate indicates an improvement

in power output and efficiency and the powe~ curve shifts

to the right along the turbine apeed scale the advantage

ot draft tube con~ol of the flow will hav been demonshy

strated

Chapter IV

A E9J11pment

ih turbine used in this test is lJ 5 1nch Pelton

reaction turbine with a rated output ot 30 horsepower under

a head of 56 feet at a speed ot 720 reYolutiona per minute

Views of this turbine are hovn in Figures S and 6 The

turbine is installed on a concrete pad located over an open

channel in the Hydraulics Laboratory at Oregon State Colshy

lege The date of manufacture of this turbine was 1915

The water was delivered to the turbine from a sump

reservoir by two pumps operating 1n parallel Each pump 1a

an 8 inch Pelton double suction centrifugal pump witb a

rating of l$00 gallons per minute at a head ot 75 teet with

a speed ot 1175 revolutions per minute Tbe inlet tlange

ot tne turbine is $pprox1mately 18 feet above the center

line of the pump

A direct current generator was coupled to the turbine

to receive tne power d veloped as shown in Figures 4 and 7 The generator is a Spr gue Electrodynamometer rated at SS horsepower with a speed range of 7$0 to l$00 revolut1one

per minute The classification is type LO 26A 2)0 volta

Figure 5 - View of Test Turbine

Figure 6 ~ View of Test Turbine

and 149 amperes lbe generator ti ld was aepar tely

excited using direct current from a motor g n r tor ampt

(l$ p 4~8)

The power output of the generator waa dissipated in

the water rheostat (3 p 488-489) shown in Figures 9 and

10 The galvanized tank contain d water ot variable d pth

on an electrode ot cast iron m aauring 1bull x 1 x 1

In the initial installation of the turbine it was

intended that the power output should be measured with a

Prony brak bull For th purpoa68 or this teat it was decided

that the brake was too instable and the generator was

substituted The platform for raising the generator the

nee asary two teet for alignment was built out of available

material In this case heavy laminated wood blocks reiashy

torced with other timbers were used and bolted through the

concrete deck (11 Pbull 36-$7)

Due to the light concrete deck the lack ot mas in

the platform and the slight misalignment in the flexible

coupling ao e vibration waa encountered It seemed to

ncr aae linearly to a maximum at the speed of bout 750

revolutions per minute Above this speed no vibPation was

noticeable The vibration waa not se~ere and does not

appear to have materially affected the test results

26

B Intrumentat1on ~ eaeur1ng Devices

The pressure head at inlet to the turbine vaa meaave4

bymeane ot two )6 inch waterbullmeroury manometerbull connected

in series as shown in Figure 8

The terminal voltage ot the generator vas meaeured by

a laboratory voltDleter with a range to )00 yolta and callbull

brated to within 15 Yolta

The armature current bull and hence the line current was

measured by a laboratory ammeter with a range to 150 amperea

and callbrated to w1 thin o 7S amperes

Tae rate ot tlow was established by weight and time

meaeurementa The weighing ank has a capacity ot 121 000

poundsJ the weight belng indicated by Toledo direct reading

scales Timing was done with a hand atop watch with clivibull

aion ot 02 second

he ~ater level in the tailrace was dete~1ned by a

hook gauge lhie was read to the nearest 001 toot

The turbine and generator speeds were eaaured by a

hand tachometer The technique of almost cont1nuoua readbull

ings of the speed gave an error ot no more than 5 revolubull

tiona per minute

c Operational Procedure

Atter the water level in the aump was checked to

insure an adequate auppl7 the puapa were primed and

27

Figure 7 - Test Generator and Plattorm

Figure middot8- Instrument Board and Field Rheostat

28

started After venting they were valved for operation 1n

parallel

The motor generator set was started to supply the

field current and the circuit breaker was closed Water

wa added to the water rheostat to the level shown in

Figure 10 ~ field current wae minimized by cutting in

all the f ield resistance in the field rheostat of Figure 8

The l2 inch gate valve shown in Figures 5 and 6 waa

slowly opened and the turbine and generator brought up to

speed The 12 inch gat valve and turbine were vented and

the pumps were checked to insure neither had lost ita prime

lhe water rheostat offers very steady load 1f the

water level is essentially constant and the water temperabull

ture 1a fixed () p 488~89) In order to maintain this

constant temperature it was decided not to circulate the

water in the rheostat but rather to allow the water to

boil thua achieving the desired result A standing wave

was set up on the face ot the electrode by the boiling

action but a atable load was eatablished except at very

low water leYels where th11 agitation led to fluctuationa

in the line current

After putting the turbine and generator on the line

maximum power was dissipated in the rheostat by redueing

the turbine speed to between oSO and Soo revolutions per

minute Salt vas added to the rheoetat wat r to increasemiddot

29

Figure 9 - View of Water Rheostat

Figure 10 - View of Water Rheostat

Separate Field ExcitationFrom Motor-Generator set Compound Water-Mercury

---shy

re Manometer

I Q)

~ 0

~

Book Gauge

Open Channel

I

Slap Reservoir

Figure 11 - Wat~r Flow Diagram and Electrical Layout

31

waiting pe~iod ot perhaps an h~ followed

while the boiling point or the water wbulls reacbe4 During

this ti+ne the manometer was vented end eheoked electrical

measur1ng 1nstlUments were connected end the hook gauge was

adjusted tor elevation

It required about two- houtte tor the generator to reach

its normal operating tempe-ratu~e_ After the water in the

rheostat and generator had reached their operating temperabull

turea it was possible to begin the taking of data

The only vaPiable which was controlled wee the turbineshy

generator speed However the upper l1ut1t of safe line

current was slightly over 100 ampJilPampPes and the eireuit

breaker would open when the current reached lOS ~ere bull

Control was exercised by means ot regulating the water

level and salt 1n the water rheo tat and the res1stsnoe of

the tield rheost t~

The etfeet ot each type ot regulation on the three

variables is shown below

Volta Aaperebull Speed

Inc Dec Inc Dee~ Inc Dec

Wa~e1 Level Inc Dec~ X

X X X X

X

Salt Concentration

Inc Dec X

X X X X

X

field Resistance

Inc Dec

X X

X X

X X

32

Jlot all methods gave the ame amount ot change in a

given variable and a period of experiment and trial led to

the following scheme starting the rune with the lowest

turbine speed the water level was high with a high amount

ot salt and the field resistance was cut completely out

Aa it became necessary to increase the speed tor each

aucceasive run either cutting in t he field resistance

decreasing the salt concentration or lowering the Vater

level would produce the desired result However decreasbull

1ng the salt concentration had to be done Without a net

gain in water which led to a tluahing procedure that was

not particularly good because cold water was introduced

which required time to heat to the boiling point Cutting

1n additional field resistance was a good method but th1a

increased the amperage possibly to the point of opening

the circuit breaker Lowering the water level was aatiashy

factol1 until the level got too low causing the current

fluctuation previously mentioned Actually it turned out

that a combination of lowering the water level and cutting

field resistance in would carry the speed from ita minimum

to 1ts maximum value it the proper choice were made each

time the speed waa to be changed At the conclusion of

each aet of runs at a high speed the water level would be

low and the field resistance high

33

TURBINE

PAD AND DECK

TAILRACE

WATER SURFACamp

CONCRETE

DRAFT TU1B INSERTS

7 5( DRAFr TUBE

FLltJI ARIA

5~ DRAFT TUBE

FLOI ARSA

Figure 12 - Sketch of Draft Tube and Test Inserts

34

Figure 13 - View of Draft Tube Insert

Figure 14 - View of Draft Tube Insert

D c __ ~s_middot hedu_le of

A number was assigned to each run The fi~st number

applies to the draft tube tlow areas

1 bull 100~ flow area or 0~ oonatriction

2 - 7S tlow area or 2$ conatr1ct1on

3 SoC flow area or so~ constriction

The second number refers to the wicket gate openings

9 over gate opening

6 bull intermediate gate opening

4 bull one h lt gate opening

The third number 14entif1ea the location of the particular

1Wl in a set ot rona made at a given dratt tube tlow area

and wicket gate opening

fnua run number 1bull4bull10 would identity this as the

tenth run ot a set made at halt gate with 75 ot the draft

tube t1ow area

Rune w re made tor a g1yen dratt tube condition

Firat tor tull 41-aft tube flow area seta ot rune were

made for the overgate halt gate and intermediate gate

conditione An insert was placed in t he draft tube and

rune based on the same gate conditions were made tor the

7S~ draft tube flow area case The insert was then changed

to allow only $~ draft tube flow area

The inserts are sketched 1n Figure 12 and photographed

ln Flgurea 13 and 14 They oonaisted of circula~ segments

36

or l2 ineh plywood mount 4 on wooden legs 10 inches high

The 1nse7te were placed in position and secured by th use

ot a-clamps on the legs and the outside ot the bottom of

the draft tube The obvious disadvantage to this method

waa the neoeasity tor draining the water from the tailrace

tor a change ot 1naert The advantage vas of course the

simplicity ot design and construction

Chapter V

DATA-A Original Data

The normal data-taking crew consisted or two men

Assuming adjustments having been made to secure a certain

turbine speed (aee section on Operational Procedure) one

man would take semi-continuous speed readings with the hand

tachometer until a state or rotational equilibrium was

reached This could be only a period or two minutes up to

ten or tifteen minutes As soon as steady speed was

assured the data taking would begin The second man went

to the weighing tank Where a minimum ot three weighingamp

were made The requirement was to get three consecutive

readings such that the ditterence between tbe smallest and

largest time did not exceed 04 seconds The time to

collect a given weight ot water was then assumed to be the

arithmetic average of the three times He then went to the

hook gauge determined the hook elevation and then

recorded the data on the data sheets The first man meanshy

while had taken readings of the line voltage line current

and manometers and checked the turbine speed by multiple

readings During the length of the run all values were

38

checked to determine mean values for recording

The minimum length of one run was about five minutes

If one or more measure ants tended to drift during the run

all values wer discarded and a new run began as soon aa

qu111br1um was stabl1shedo

B -0-al_e_u_l_a_t--d Data

The h d on the tu~bine 1 defined by

($)

The maxtmwm velocity V4 was equal to about o8 tampet per

secon4 which makes it a negligible quantity when converted

into velocity head

An engineerbulla level was used to deterine the d1ffePshy

ence 1n elevation between the compound water-mercury manoshy

meter and the hook gauge Using this value the equation

for turbine bead becomes

where z4 is the hook gauge reading

The rate of flow 1 cent

w weight or water collected average time to collect

The inlet velocity v1 vas calculated by dividing the

weight rate or flow by the specific weight of water and the

)9

area ot ~e inlet pipe This was equivalent to dividing

the weight rate of flow by 490 Then the power input to the turbine is equal to

WHpin rri

10 (6)

Also

(P ~ut) Turbine

(P out) + Generator

(P lost) Generator

The power output of the generator is simplJ the

produot ot the terminal voltage and the armature (line)

curPent The power lost in the generator can be subdivided

into copper losses and stray power losses lo evaluate

these cunes based on losses of an identical generator

11leampsured by the Department ot Mechanical Engineering were

used The loss curves are reppoduced in part in Figures

15 and 16

Determination ot generator losses proceeds as tollowau

(1) From Figure 15 detem1ne the vo1tage drop in the

armature circuit using the temperatures of 1220 F and the

meaaured current

(2) The induced voltage is t~e sum of the terminal

voltage and the voltage drop 1n the armature circuit

() Entering the induced voltage and the turbine speed

into Figure 16 the stray power loss can be determined

(4) The copper lose can be evaluated from Figure 1$

using the measured current and the temperatlll-e of 1220 P

40

25 ~------~--------~--------~------~

U) -U) - 20

f-4 ~

-~ -gt 0

0

VOLTAGE DROP

~ - i -

- bullbullbull bull - -middot-middot -+ ~- + -t--+ ~ - ~ middotbull ~-~ middott- -+----- _ -4 middotmiddot- --~-+-t---r~~ ~--+t-t- - ---t-c-++~-ulf--

0 50 75 100

Figure 15 - Curves of Generator Voltage Drop and Copper Loss

41

1200

1000

800

600

800

0

0

~-

middot--~ 1shy --1 + bull l

100

I -

150 200

IIDOOED VOLTAGB (VOLTS)

Figure 16 - Curves of Generator Stray Power Loss

_ j

-bullshy -L---- shy middot -shy

250

- r

42

(5) The generator los os equal the sum of the eopp r

loss and stray power loss

~e efficiency or the turbine is taken as

etticiency u e =P out (8)Pin

~ample pound Determ1n1gg turbine Power Output

The following data are taken trom that ot Run 1-9-1

Line voltage 1040 volts Line current 870 amperesSpeed 355 revolutions per minute

The induced voltage 1a determined as follows

Line voltage 1040

Voltage drop 90 using Figure 15 with line current of 870 amperes and temperature ot 122 degrees)

Induced Toltage 1130 volta

The power output of the turbine is determined as follows

Generator output 90$0 (line voltage z line current)

Oopper loss 7 (using Figure 15 with line current of 870 amperes and temperatUe or 122 degrees)

Stray power lose 470 (using Figure 16 with speed ot 355 revolutions per miDUte and induced voltage or 1130 volts)

Turbine power output 9527 vatta

or turbine power output 1s 12z2 horsepower

43

The conversion of the calculated data to a constant

head is based on the conventional assumption of constant

efficiency regardless of turbine head For a constant head

ot 81 teet a purely arbitrary figure the tollowing relashy

tionships are ass1lJiled to be true

I ____L (9) (i)l72

(10)

For these two values the specific a peed may be combull

putedt

N t Jt VPt (11)8 243

Chapter VI

~RESULTS

A -Pr_e_ae_n_t_a_t_t_o~n g Reaultbull

Graphical presentation ot the results ot this te1t

are given as follows

Figure 17 -Turbine characteristics with 100~ dratt

tuba 1low area

Figure 18 - Turbine characteristics with 7S dratt

tube tlow area

Figure 19 bull Comparison ot power and etticiency at

over gate conditions between 100 and

75~ draft tube flow area

Figure 20 bull COZQparison of power and ettic1ency at

halt gate conditions between 100~ and

7S~ draft tube flow area

Figure 21 bull Comparison of power and etticiency at

over gate condition between 100~ and

So dratt tube tlow area

Figure 22 - Comparison in variation ot apec1t1c

speed between 100 and 75~ dratt tube

tlow area

50

45

20

-bull - 1--shy40

bull J-~ 30

~ ex

~ 20

~~ ~ -)q

I

~ - _

- -

10~ OF DRAFT TUBE FL(Jif AREA

CONSTANT HEAD OF 8l FEST10

POIER OUTPUT EFFICIENCY SPECIFIC SPEED

0 ~--------------_--------~------~------~ 400 600 800 1000 1200 1400

TURBINE SPEED (RPM)

Figure 17 - Turbine Char~cteristics with 100 Draft Tube Flow Area

50

46

-bulllle

~ 7 ~ OF DRAFt TUBE FLOW AREA

0 -~~-rl C05STAMT BEAD OF 81 mET 1J~

POIER OOTPUT ---+- ---o ~_H EFFICIDCY ~ I shy

bull ql SPECIFIC SPEKD - ~ -

bull ~ J 10 L rmiddotr- r- -

bullz- I

~~ 30 ~~--~----~~-

20 ~ ~ middot-shy

26

~~ 25

~0 ~r-----i (

Tbull -bullshy

400 600 800 1000 1200 1400

TURBINE SPEED (R PK )

Figure 18 -Turbine Characteristics with 75 Draft Tube Flow Area

47

EFFICIENCY 60

1-----shy

-~ 50~--~--~~-~middot middot middot middot r~-~----~~~~---4~-r~-~~gtt

II

POWER~ J ~ bull bull

u I

sH

40~------+-------+---- -~~--~~-~~~~

~----~rl 1 bull

I

I

0~--------------~------_------~--------

~ -OVER GATE CONDITION

COIJSTANT HEAD OF 81 FEET

0 o 10~ DRAFt TUBE

_-- _ 7~ DRAFT TUBamp FLON AREA II

10_~-----+--------r-------r----~~

400 600 800 1000 1200 1400

TURBINE SPEED (RPM)

Figure 19 middot - Comparison between 75 and 100 Draft Tube Flow Areas of Power and Efficiency at Over Gate Conshydition

48

t

bull --4 r ~- ~ middot~

70 1-----------+-~~~~~+middot ~ ~~ middot middot -~~--~~--------~~----~-+1

-~-

Atbull bull

lla-

60

amp0

40

20

10

oampOO

t _ - - ~-+- - -~-

l2 GATB COJIDITIOJJ

COJISTABT HJW) OF 81 JBET

o 0 lOQ( DRAFl TUB8 FLOI AREA

e-- - e 75 DRAFT TUBE FLOW AREA

800 1000

- r-

~

TURBIbull SPBIID (RPII)

Figure 20 - Comparison between 75 and 100 Draft Tube Flow Areas of Power and Efficiency at Half Gate Conshydition

49

60

50

-40

bull 30

IIQbull

20

10

0

400

- t - ~

EFFICIENCY

_J bull - bull bull

~ r r middot t -+ shy L -t -

OVER GAD COliDITIOI

CONSTABT BEAD OF 8l FBB

o o 10~ DRAFt TUBE FLOI ADA middot--- 5~ DRAF TUBE FLQPi AREA

600 800 1000 1200

Figure 21 -Comparison between 50~ and 100~ Draft Tube Flow Areas of Power and Efficiency at Ove~ Gate Conshydition

50

25

20

15

10

0

Figure 22

~- T -4 -t- -l --~-

t-~ I

middot --~- t ~---- _ __ _ + --

----~- --r-- --

~-=J-~-=-~ -==~ _ ~- -- ---f---1 - shy

CONSTANT HEAD OF 81 FEBT

o--o 1~ DRAFT TUBE FLltll AREA

75C DRMT TUBK FLCIJ AREAmiddot--middot-middot 600 800 1000

TURBINE SPEED (RPK)

Comparison of Specific Speeds for 75 and 100 Draft Tube Flow Areas

51

B Discussion 2 Result

Consideration of Figures 17 and 18 indicates the

overall eftioi ncy pattern or hill is significantly or

rounded for the 7$~ flow area than for the 100~ flow area

bia implies a greateP efficiency is possible at speeds

leas than or greater than design speed with an insert in

the draft tube However the muilDum efficiency is lemiddotas

Direct comparison at over gate conditions is made in

Figure 19 ~e same general trend is noted tor both the

etticiency and power curves for the 7$~ flow area case

The eurves show higher values at overspeed than do the

correaponding cWvea for the 100 flow area case It ia

not clear whether the curves have been shifted by the dratt

tube constriction or whether the curves simply bulge past

the normal curves at both overspeed and underspeed condishy

tions The power curves apparently peak near the aeme

point bullalthough maximum power is still obtained with the

normal draft tube area

For the comparison at halt gate operation shown in

Figure 20 a general improvement has apparently been made

by restriction of the draft tube flow area At every speed

the etticienoy and the power is greater for the restricted

tlow case The two ett1o1ency curves and two power curvea

are practically parallel throughout the speed range ot

teat

As the flou aroa i e decreased still farther a s1gn1

ticant change appears Reterr1ng to Figllle 211 tor the $0

flow area curves it a obvious that exit losses have

become excessive at the overgate condition because the

efficiency and power are everywhere leas than tor the case

of normal draf t tube area

Earlier it was pointed out t hat 1t the r esult s 1nd1bull

eated an increase in both power and ef tieiency- t hen it

could be assumed tha t the additional los s i ntroduced with

the draft tube insert is less than the diminished losses

due to leas shock losa and water passage losses For the

places where both the efficiency and power have been

increased we can assume that the insert has improved turshy

bine performance

For the places where the power haa been decreased

nothing can be said as to the elimination of ampbock loss

because the new lose present with the drat tube insert has

overshadowed any gains in eftecti Ve head upatJ-eam of the

insert

Near the peak of the efficiency hill howeve~ it may

be pointed out t hat shock loaa ie a minimum with a normal

draft tube and the insert merely adds an additional loss

with the resultant decrease in maximum efficiency tor the

7$~ flow area case

Perhaps the most s1gn1ticant set of eurves is shown aa

53

Figure 22 In this graph values of specific speed tor the

75 and 100~ flow area cases for both over gate and one

halt gate openings are plotted against turbine speed At

every speed and both gate openings the value ot specific

speed for th 75~ flow area case is greater than that for

the 100 t1ow area ease

Since the head is a constant for both situations this

may be interpreted in either of two ways trom equation

(11)

(1) For the same turbine apeed restriction of the

draft tube t1ow area resulted in greater turbine power

(2) For the same power amputput the turbine with 75~

draft tube flow area operated at a greater speed than did

the one with 100 flow area

Since the required diameter of a turbine varies

inversely with the speed the second interpretation could

be stated such that a smaller turbine could be used to

develop the same power output

Whether viewed trom the aspect of increased power

greater speed or reduced size the performance of the turshy

bine with reduced draft tube flow area is superior to that

with the nolmal flow are in the draft tube

The curve of specmiddotific speed versus turbine speed for

the so draft tube flow area case at over gate cond1t1ona

was not included in Figure 22 This curve lies below that

for the 100~ flow area c se at all speeds

In elaboration ot the second interpretation of Figure

22 attention is directed to the relative magnitudes ot

increased apee1f1c speed tor the two gate openings Assumbull

ing that the increase in specific speed implies a shift ot

the power curve to the right along the turbine speed scale

the power curve would be shifted more tor tbe halt gate

opening than tor the over gate opening

It thia trend could be extrapolated to the other gate

openings the tendency can be seen tor the line ot beat

speed to rotate toward the line of the operating speed as

illustrated in FigtU-e ) The advantage of this has already

been discussed

This particular turbine has a low specific speed tor a

reaction turbine Aa the rated value of apecitic apeed tor

reaction turbines increases the line ot beat speed departs

even more radically from the line of operating bullpeed It a

test similar to this were conducted on a reaction turbine

ot gleater specific speed it is pJobable t hat the rotation

ot the line of beat apeed would become more p~onounced

The scheme used in th1a teat had two obvious dr wbull

backs The first was the decision to leave all the wicket

gamiddottes installed tor all conditions ot the draft tube

These gates predominated in control of the tlow The

inserts added to the draft tube merely acted as auxiliary

55

contrGla

The aecond drawback was the choice or device to place

in the draft tube The reasons foll selection of this type

of device have been previously mentioned It is to be

anticipated that adaptation ot dratt tube flow control

would result 1n a better device for an actual turbine

installation Such apparatus might take the form of a

pneumatic bladder or a h7drau11oally operated variable

venturi section in the draft tube It is conceivable that

the gate as used in this test might be adapted also

Chapter VII

OONCLtJSIOfS

From the results of this test the following eonolubull

e1ona aa to the effect ot a variable draft tube flow area

on the performance or a r action turbine may be drawn

(1) The effect ot a variable draft tube tlow area 1a

generally favorable upon the operat1Gn ot a reaction turbull

bine because or the tendency tor the line or beat speed to

rotate toward the line ot operation This resulte in

better performance of the turbine at partbullloads

(2) he etf1o1ency eh111 tor the turbine beeomaa JDore

tlat at the top leading to a smaller max1JilWD effic1enc7

but e reater etticieney at other pointe of operation with

the insertion ot an auxiliary control ror the rate ot tlov

in the draft tube

(3) The power output of the turbine will increase at

over speed over gate conditione as well a at part gate

conditions with the proper amount or draft tube eonatr1cbull

tion or flow

(4) It is possible to eliminate at least partially

eddy type shock loss by tho introduction ot flow control

in the draft tube

BIBLIOGRAPBl

1 Addison Herbert A treatise on applied h-draul1cs New York Wiley 1954 724 Pbull

2 Allen o M and I A Winter middot Co111parative testa on experimental draft tubes Tranaact1ons ot the American ociety ot Civil Engineers 87t893bull970 1924

3 Barrows a E Water power engineering 3d ed ew York McGraw-Bill 1943 791 Pbull

Bovet G A Modern trenda in hydraulic turbine design4middot in Europe Tranaactions of the American Society ot Mechanical Engineera 75975bull993 1953bull

s Oreager William P and Joel D Justin Hydroelectrichandbook 2d ed New York Wiley 19$0 1151 Pbull

6 Daily Jamea w Hydraulic machinery Int Hunter Rouses Engineering hydraulics Hew York Wiley 19$0 p 8$8bull99

Daughertybull Robert L Bydraulie turbines ew Yorkbull7middot MoGrav-Hlll 1920 281 Pbull

8 Daugherty Robert L Inveat1gat1on of tne performance ot a reaction turbine ~anaactiona or the American Society ot Civil Engineers 7811270bull1304 1915

9 Davie L M Model and prototype testa Int Trend in hydraulle turbine practice symposium lranaactions ot the American Society ot Civil Engineers 1o63S3middot368 1941

lfJ Doland James J Hydro power engineering Hew Yorkbull Ronald 1954 209 Pbull

11 Gandy Theodore s and Elmer c Schacht Direct curshyrent motor and generator troubles operation and repair New York McGraw-Bill 1911 293 Pbull

12 Gibaon Arnold H Hydraulics and ita applications5th ed London Constable 1952 813 Pbull

58

13 Button s P Component loases in Kaplan turbinebull and The prediction of efficiency from model tests Probull coedings of the Institution or Mechanical Engineers168743-762 1954

14 Knapp R T~ Oavit t1on mechanics and its relation to the d sign or hydraulic equip ent Proceedings or tne Institution ot Mechanical Engineers 166150bull16) 1952

15 Langsdorf Alexander s Principles of direct curHnt mach1nee 5th ed New York r~cGrawbullH1ll 1940 746 Pbull

16 Lsrner Chester w Characteristica of modern hydraubull lie turbines Trans e~ions of the ~~erican Society ot Civil Engineers 66306-386 1910

17 Linsley Ray K Jr and Jobulleph B Franzin1 Eleshyments of hydraulic enginebullring New York McGrawshyBill 19$5 $82 Pbull

18 Mead Daniel w Hydraulic machinery llev York McGraw-Hill 1933 396 Pbull

19 ead Daniel w Water power engineering New York McGrawbullRill 191S 843 Pbull

20 Mockmore Charles A Part gate operation at water turbines Corvallis Oregon State College Department ot Civil Engineering 1933 11 numb leaves (Unpubshylshed typescript)

21 Mockmore Oharles A Flow characteristics in elbow dratt tubes Transactions of the Amez-ican Society ot Civil Engineers 103402middot464bull 1938

22 Moody L F Hydraulic machinery In c v Davis Handbook ot applied hydraulics New York McGrawshyHlll 1942 1082 Pbull

2) Ptau At-nold Hydrbullulie turbine handbook ld ed Milwaukee AllisbullOhalmers ManufactUIing Company 1948 70 Pbull

RheingalUI w J Recent developments in Francis turshybines Mechanical Engineering 74189-196 1952

25 Russell George E Hydraulica 5th ed New York Henry Holt 1942 466 Pbull

26 Safford A and E P- Hamilton American mixed tlow turbine and ita setting Tranampactions or the Amerieal Society of Civil Engineers 851237bull1)56 1922

27 bull Spannhake W1lhe1Dh Problems or modern pump and tur b1ne design Transactions of the American Society of Mechanical Engineers 56e22$-248 1934bull

28 Sutherlandraquo R A Better ethod or representing and middot tudying water turbine performance ~ansaetions ot thmiddote American Society of Mechanical Engineers 68t675bull 686 1946

29 Teats ot five models or draft tubes tor turbines Engineering News-Record Pbull 182-184 Aug 2 1923

30 White w M American hydztaulic turbines Mechanical Engineering S2t390bull39S 1930bull

31 White w M lhe hydraucGne rega1ner1 its developmentand appl1eat1ons 1n hydroelectric plants Meohanlobulll Engineering 43t37Sbull380 1921 middot

32 Winter I A Economic principlebull in designbull Int Trend in hydraulic urbin practice bull a ampoeiumTranaaot1ona ot the American Society ot Civil Engineerslo6332bull3S2 1941

33 Wiel1cenua G F Fluid mechan1ca or turbo-machineryNev York McGraw-Hill 1947 613 Pbull

APPENDICES

c

Appendix A

NOATIOB

A Angle between the absolute velocity vector and the tangent to the rwmer Subscripts 1 and 2 refel to entrance and exit ot the runner blade

B Angle between the relative 1elooity vector and the tangent to the rwmer Subscripta 1 and 2 refer to entrance and ezit or the runner blade

Angle between the tangent to the runner blade tip and the tangent to the runnel- Subscripts 1 and 2 reter to entrance and exit of the rt1rmer bladebull

Blade angle-gate opening conetant defined by equation (1)

e 09erall efficiency

g Gravitational acceleration assumed constant at 322 teet per second per second bull

H Turbine head detined by equation ($)

m Exit loss coeft1e1ent

Turbine speed expressed in revolutions per minute

Turbine speed under a constant head of 81 teet

specitic apeed of the turbine under a constant head ot 81 teet

p Power output in horsepower ot the tvbine

Power output of the turbine Ulder a constant head ot Sl teet

Pl- Pressure head at entrance to the tUlb1new

l1 Peripheral velocity ot the runneP Subacr1pta 1 and 2 refer to entrance and exit ot the JUnllampr blade

62

v Relative velocity reaulting trom the combination ot the absolute water velocity V and the runner periphshyeral velocity u Subscripts 1 and 2 refer to entrance and exit ot the runner blade

v] Relative velocity vector necessary to produce a tanbull gential entry into the runner blades

V Absolute water velocity Subscripts l and 2 refer to entrano and exit ot the runner blade

v2 Velocity head Subscripts 1 and 4 reter to the ~8 entrance to the turbine and the tail~ace wate~

w Unit weight ot water assumed constant at 624 pounda per cubic toot

V Weight rate ot flow in pounds per aeooncl

XX Velocity component ot ahook See Figule 2

Z Elevation head Subscripts 1 and 4 reter to entrance to the turbine and the taibace water surfacebull

Appendix B ORIGINAL DATA-Run

lfwnber

0-4-1 0-4-2 0-4-3 o-4-4 o-4-S o-4-6 0-4-7 0-4-8 0-4-9o-4-lo o-4-11 o-4-12 0-4-13

o-6-1 o-6-2 06-3 o-6-4o-6middotS o-6-6 o-6-7 o-6-8 0-6-9 o--6-lo o-6-11

Speed

rmiddot2middotbullmiddot(1)

336 38$ 451 S$9 620 669 6lt)$ 120 787 860 932

102imiddot109 bull

352 355 443middot 543middot 620 654AJs32

911 1001 1111

~essure Head rt (2)

410 410 416 426 431 43-7 439 44-9 452 467 482 soo $1 bull $

350 351 35middot7 )66 37-9 37-9 392 41 bull 3 43middot3 460 489

Elevation Bead

fjj $7 $7 $7 $7 $7 $7 51 57 5-15858 $8 58 56 56 $6565656 51 575As5a

Velocit Head

flj 07 07 07 06 06 06 06 os 05 os0404 03

09 09 oa o8 o8 os 07 07 06 o~o

Total Head rt ($)

47middot4 4A44 o 489 49-4 soo $02 $11 $14 $29 5imiddot45 2 576

41 bull $ 416 421 430 44middot3 44middot3 456 47-7 496 523551

Plow

lbtjec

326 324middot317 311 306 30029middot28 middotmiddot middot 386 275middot260 240 218

359 36~35 bull 349 345middot 339 330 318 300 273 240

Line Potential

vyqjbull 1060 1220 ~-0o 1920 2150 2000 2$60 2000 1940 18)015io11 o

1000 1100 139bull5 1760 1925 16$0 1620 1610 1540 1330 870

Line Current

amlscs 960 900 830 740 730655 70bull 0 530 660 600 5imiddot54 6 )60

982 930 860 780 ~3-545

79-5 74-5 670 560 370

P

Appendix B ORIGINAL DATA (Continued)

Run Number

Speed

Pbulltmiddotbullmiddot )

leasure Head ft(2

Elevation Head tt(J)

Velocity He-dfmiddotj

Total Bead tt($

Flow

lbstsec( )

Line Potential vo~ta( )

Line Current

amjs (sect

0bulllt)-1 0-9-2

3ll6 398

28o ~~1

$6 56

1o 10

346 347

390 365

1ooo 1190

aao 835

0-9-3 0-9-4 o-9-S

472 565 632

292 305 312

$6 s6 56

10 o9 o9

)$8 J7~o 37~7

381376 37o

1)6614oo 141o

820 ass ass o-9-6 0-9-7 0-9-8 o-9-9 0middot9-10

680 120 762 844 920

)24337346 366 390

56 $6 56 57 $7

09 os o8 oa 07

)89401 410 431454

367~ 357348 34o 322

1400 1J6o l36o 1310 1170

843 820 7957So 67~0

0-9-ll 0-912

1001 1100

41 bull 7 45-3

s 7 6~0

06 os 480 $18

299 268

980 65$

560 36~5

1-4-1 1-4-21-4-l1-4shy1-4-5 1-4-6 l-4-7 1 4-8 1-4-9 1-4-10 1middot4-ll 1-4bull12

354middot452 562 62q 674shy102 752 760- 863 932

1022 1100-

)82389 4014oa 416 41--7 423 428 44-2 45-7 486 49-2

51S757 51 5-7 5middot15zs sa $8 58 59

07 07 06 06 06 06 06 os o bull o 04 o J

446 45-)46middot4 471 ti7-9480 q86 491505 $19 548 55-4

)28 320 311 306 300 295 291 286 269 2582iimiddot21 bull

1080 14Lo 1550 153-5 1470 141-0 1385 1310 1310 1230 1120 855

970855 875 91-0 94~0 975 966 995 860 77-S 610 4fo

0 ~

Appendix B ORIGINAL DATA (Contirmed)-Run Speed Pressure Elevation Velocity Total Flow Line Line

Number Head Head Head had Potential Current rtjjmbull t~ bttec vyfs am~a12) ( ) ti fli 8

1-6-l $6 33$ $6 0bull9 400 364 1100 93 0 1-6-2 41 34laquo2 $6 oa 406 JS7middot iios a5s l-6-3 500 3~0 5bull6 os 356 1 1 o aos 41middot~1-6~4 35bull4 5-6 oa 41middot 352 16~0 82 0 5~1-6-5 5 bull 36_2 Sbull6 08 42bull6 349middot 161 ~ 0 86~0 1-6-6 622 366 $6 oe 43bull0 345middot 158 0 88~$ 16-A 649bull 37bull1 56 os 43-S 342middot 1570 895 1~- 386 57 07 46-0 192 ) 125A44 333middot 1-6-9 3) 404 5middot1 07 468 317 1620 675 1610 911 42-4 5-7 o6 48-7 298 168 0 61 0 1-6-11 999 451 56 os Sl ll 276 ~2-0 530 1-612 1115 485 58 04 54middot7 238 90 )3 0

1middot9-l 355 279 56 10 )45 385 1040 870 1-9-2 399 28J $6 10 )49 38$ 1140 86 5 l-9-3 ~ ao 291 56 ~0 35middot1 J8J_ JJ6o 815 1bull9-4 579 303 56 09 )68 375middot J4JO 830 l-9bullS 40- 313 )6 09 31middot8 370- 1460 82~0 1-9bull6 679 2) 56 09 3 bull8 364middot 1670 710 l-9-7 682 319 56 o9 384 ) 62 1460 79 5 l-9-8 724 33middot5 56 o8 399 3$6 bull 1480 76 -5 1-9-9 762 34middot3 $6 0 bull 8 407 )48 14910 13middotS 1-9-10 833middot )60 5middot7 os 42$ 339 144$ 686 1-9-ll 926 39middot1 5-7 07 455 318 1290 600 1-9-12 1000 41middot3 0-6 476 298 1115 510$ ~ 1middot9-13 1105 452 s o4 $14 2$6 710 )10

~

Appendix Bt ORIGDIAL J (Continued)

Run Speed Pressure Elevation Velocity Total Plow Line Line Number Head ltead Head jlamp$d P()ten~ibulll Current

r~~~m ft ft lbs~seo voltattj rgj twimiddot t 1 t2gt lt3 ou t ( rt

2-9-1 384 289 S 6 10 35 5 1400 1170 810 2-9-2 443middot 29$ $6 ltimiddot9 360 379middot 11(0 87$ 2-9-J 536 30bull 3 sc 09 )68 374middot 1)40 84 bull) 2-9-4 571 306 $6 09 3~1 372 120bull 0 955 2-9-5 623 316 S6 09 J l )6S UJSo 77$ 2bull9-6 669 327 S6 09 )92 )61 1240 905 2-9bull7 712 )39 56 os 40-3 351 12(0 86 bull0 2-9-8 ~5$~ J48 56 oa 412 348 1290 81 bull ) 2-9-9 04 )63 56 oa 42-7 339 12ltJO 76$ 2middotmiddot9-10 8$2 376 5middot1 07 440 33~- ~ o 710 2-9-11 955 394 5-1 o6 457 300 1100 506 2middot9-12 1000 421 $7 06 48middoti 295 1020 $18 2-9bull13 110~ 463 56 05 $2 267 620 3~0

oshy0

Appendix Gt CALCULATED DAgA

Turbine Run Generator Generator Turbine Turbine Efficiency Turbine Turbine Specit1c

Number OutputKWlt21

Loa~Jes KWlol

Outut K bull (H)

Input RP 12)

middot Percentlt13gt

Speed r~Jmiddot(

0ltput HP ~1

Speed r-m

( 6) middot

o-4-1 0middot4-2 0-4-3 0-4-4 0-4-5 0-4-6 O-qmiddot7o-4-8o-4-9 0-4bull10 0-4-11 o-4-12

1018 1o9a 1220 1)62J40214oa1J4oo 1357 1320 1164 997 718

046 o59 071 092 096 1071oo 134 104 100 109 107

14261sso 17)01948 2008 20322011 1999 19 09 1708 14-84 11o6

281279 27-7 276 215 273271 268 268 26h 258 24-5

soa 555 62$ 705 7)1145 742 74-6714645 51s 45-1

440 sos 585 720 195 sso sao 9$$ 985

1065 1135middot 1230

318 357 319 416 422 419412 39middot9 378 324 260 191

102 12bull4 148 191 21bull 3 22o 233 249 24924middot9 238 221

0-4middot13 418 104 699 228 306 1300 117 18)

o-6-1 982 045 1376 271 $08 496 376 124 o-6-2 o-6-3 G-6-4o-6-5 0-6-6

1023 1200 13 73 J415 139h

051 0middot66 oaa ()bull 96 088

14-39 1696 1958 2026 1986

276 27middot4 273 278 274

$20 61 8 717 7)0726

q95615745 8)5685

390 ll5middot3 sos soo 490

127 170 218 243 2$$

o-6-7 o-6-8 o-6-9o-6-lo

1288 1199 1032 7-45

o9o 094 09$ 096

1846 1733 1511 1128

274 276 271 260

67S 629559 43middot4

980 1085 1165 1245shy

436 )83316 21bull 7

266 276 270 239

0-6-11 322 1oo 566 2141 2JS 1350 101 177 0 --4

Appendix C CALCULATED DAlA ( Continued)-Run

Number Generator Generator

Out2ut Losaes xw LW- 12gt (lO)

Turbine Out2ut

ltPlJ

Turbine Inat lfP Jig)

Etpound1e1ency

PireentDl

Turbine Sed x-~m( 1

Turbine OutEut RPJl)

Turbine Specific

SeeedrIbullntbull

( 6)

o-9middot1 0-9-2 0-9-3 o-lt)-4 09-$ 0bull9-6 0-9-7 0-9-8 0-9-9 0-9-10 o-9-11 0-9-12

aao 994

111$ 1197 1206 1180 11)21081 982 784 5-49 2)9

0middot45oss o6$ 070 07$ 0-77 (l77 or~ o s06o 8 096

123~ 1402 1$80 1698 17bulllS 168$ 16bull18 ~middot5430 1151 a~J4 9

24middotgt24middot3248 25~25 260 260 259 267 266 26middot1 2S2

sos 577 63-7 671 676 650 621 60036J4

327 178

$) 610AlO 3$

92S 980

102$ 1070 1157middot 1230 1300 137Smiddot

44middot4 soo 523 ssomiddot 540so6 46-5 432 368 274 18~8

J46 176 21-1 255 2802s_A 28 289 288 265 231 168

1-4-1 1-4middot2 1-4-3 1-4-4 1-4-5 1-4-6 1-4-7 1-J-8 1-4~9 1-4-10 1-4-11 1-4-12

10bull48 1231 13-S6 1397 1)821375 1))8 1303 1127 953 683) 51

048 067 o7A07 0 bull79 oa1 oss o bullao osa 0lt)0 096 099

J468 1740 1921 1978 1958 19$1 1911 lSSi162 1)98 1045

603

266 264 262 262 261 2512$7 2$6 24middot7 24-3 233 217

551 660 13middot3155 75-6 7~-97 middot4 72$ 67 51middotJ 44middot9 21middot1

475 605 A4220

875middot 910 970_

1000 1090bull 1166 1243 1330

5816

44middot444middot5 430 427 412 392 329 273 188 l0-7

117 101 204 22$ 2)7245 2562sa 257251 222 179

a-C))

Appendix Ct CALCULATED -DATA ( Ocntinued)

1-6middot1 1023 o$2 14-41 26S 505 41~6 26~

54middot5 13middot3l-6-2 1201 067 1boo 625 47-9 17shy~middot41-6bull3 1296 oA9 1 middot43 26 9 700 so5 20bull 4 l-6-4 l3j5 o 0 19~09 268 71bull3 A5o 514 222 1-6-5 1) 5 o81 19(gt4 271 725 51-5 238 l-66 1398 081 198) 27-0 736 8 S13 252~-middot l-6j 1405 083 199i 211 733 885 $middot06 2$9 l-6 13middot9~ 103 2amp 0 279 71 8 985~ 467 ~-69 1228 1 bull 02 17-SS 270 661 109$ 407 ~3~ l-6bull10 1025 100 lSll 26i 573 1175middot 27~S32middot~l-ampu 153 1-00 llft3 26 444 1270 22 24bull8 1bull6-12 294 100 52a 231 22 3 1360 95 172

1-9bull1 904 048 1275 2J4Z $28 S4$ 459 1$2 1-92 98$ oss 13-92 24middot4 57-0 6JO 49bull1 176 1-9middot3 1110 066 1$76 24middot9 63middot4 I2o 536 21-7 l--9-4 1187 072 1685 251 66$ 5 $$ bull 0 261 1middot9-5 llltJ7 1710 25middot4 67-3 93$ 536 28~20-671middot9-6 1186 o 8 1708 25-7 67) 980 $15 2691-9- 1161 oBo 1660 2$middot3 6$6 990 508 29-1 l~- ll-32 oB) 16sect0 2$8 632 1030 471 291 1-9bull9 109$ oa5 2$7 614 1075 29S~middot 0 4imiddot41-9-10 9~91 oas 262 S$1 1150~ 3 o 292 1-9-11 o9o u57 12JiO 21gt 26-77middot74

-45 26sect ~middot91-912 $69 091 sas 25 middot3 1)0$ 196 2J-8 1-9-1) 220 098 426 2)9 178 1390middot 84 16 6

0 0

Appendx C CALCULATED DATA (Continued)

Turbine Run Generator Generator lurbine Turbine Eft1e1eney Turbine lurbine Spee1f1c

Number Output Losses Outit Input Speed Output SPed middot k_-V KW R _ H_bull_P Percent r Thm HP rpm_ (9) tlo) 11) middot (12 _) (lJI ( ) (1$ (14)

2-9-1 9--46 055 1)62 258 528 580 164 2-9-2 1024 056 248 58 4 665 4 9 191iimiddot48 4~middot0 2-9-3 1132 067 05 2$0 641 795 52q 237 2-9-4 1148 065 1027 2$1 -~8 845 525 252 2-9-5 11 77 oso 16-83 253 6 910~ 522 270 2-9 6 1122 071 1600 251 622 960 47-5 2722-9-A 1092 015 1562 257 608 1010 445 2z12bull9- 1052 079 1514 261 580 1060 41middot7 2 2 2middot9-9 986 o82 ]429 26) 542 1105 372 277 2-9-10 915 086 1340 268 500 1160 334 27-6 2-9-11 638 087 972 254 )81 1270~ 229 250 2-9-12 )28 090 828 259 )19 1295 179 226 2-9-13 192 094 383 2$ 6 150 1370 7 3 152

-3 0

Page 11: The Effect of A Variable Draft Tube Flow Area on the

4

Figure 1 - 135 Inch Reaction Turbine

5

must operate at a constant speed or rotation even though _

the power demand ohangos In thiamp case the turbine nuet

be eap~able or producing a range of power output yet menshy

ta1n e eonetant speed

Speed regulation of the turbine iv accomplished by

means ot a governor (23 Pbull 24bull3-7) bull The contr-ol or regulashy

tion 1s indirect that i s the governor actually exereiaabull

control over the water in order to JJaintain e given speed

Co-ntrol over- the turbine end bence its speed and

power is the function ot a ring of movable wicket gates

located just upsttteam of the turbine runner These w1eket

gates 1n the process of opening and closing upon eeeh

0~1ar in a rotational manner actually control the amount

velocity and direction of tne water passing throu~~ them

C Draft Tubes

It has been found that the effeetive head on a reae

1l1on middotturbine is increased with the addi timiddoton of a draft tube

(3 Pbull 256bull264) Tne draft tube does thin by~

(1) Making a greater presaure d~op across the turbine

possible by the creation of a negative pressure at the

discharge or the runner and

2) DeoreaGing the k1net1e energy lost by increasing

the eross sectional area at exit

he draft tube permits the turbine runner to be

6

located above the tail race water surface without the

sacrifice of head However cavitation will cause pitting

of the turbine if the difference in elevation is too great

A common maximum elevation difference is 19 feet although

this figure is quite subject to modification between difshy

ferent installations (3 p middot 264-266)

There are many different types or draft tubes in use

today the choice or type being largely a matter or

economics (2$ p 368-370) A very common type particushy

larly among the smaller units is vertical with flaring

sides However the angle of flare is limited by the possishy

bility of separation of the flow from the sides In order

to achieve a certain discharge area the length of the tube

may be such as to require a great deal of excavation In

oases or this sort the cost of this excavation must be

balanced against a more elaborate design that does not

require as much excavation Other draft tubes in use

include the elbow hydracone and spreader types

Despite the differences found in construction and

design the draft tube must accomplish the desired objecshy

tives while offering a good hydraulic geometry to the flow

passing through it An inefficient draft tube defeats its

own purpose

Ohapter II

DISCUSSION ~ TURBINE LOSSES

A General

lhe head that 1a actually utilized by the turbine 1a

less than the effective bead as defined by equation ($) by

the amount that 1a lost due to mechanical and hydraulic

reasons

Mechanical loaaea are a function or the turbine 8p$ed

fhis ia not a lineaz- function but varies eomewhere between

N and N2 (3- Pbull 224)

Hydraulic losses encounteled in turbines ma- be subshy

divided aa to the location or occurrence (3 p 225-227) aa

fOllOW$S

(1) Penstock and scroll case

(2) Wicket gates

(3) Between wicket gates and turbine runner

(4) Runner passages

(5) Runner exit into draft tube

(6) Draft tube and

(7) At exit from the draft tube

The flow in the penstock scroll case wicket gates

runner passages and draft tube may be envisioned as

examples of flew in conventional pipes elbows and convergbull

1ng passages If this comparison may be made it could be

assumed that the losses encountered in these locations

would be proportional to vn ~ value ot N is normally2g

aesU111ed to be 2

he losses encountered between the wicket gates an4

the turbine runner and exit lossos are special cases which

will be discussed separately

B Shock toes_

The flow betwe n the wicket gat outlet and the runner

blade entrance is or particular 1nt rest because no direct

comparison vith common flow situations is obvious

Conaider the vector diagram (7 Pbull 7576) in Figure 2

The veetoo v1 is the absolute entering velocity of the

water and is fixed in magnitude and direction by the setbull

ting or the wicket gates The vector l11 1e the peripheztal

velocity of the runnel which tol any given turbine 1e

dependent only upon the turbine rotational speed The

combination of these two vectors ylelda the third vector

v1 which is the relative entering velocity ot the water

nere is only one setting ot the wicket gates for a

given turbine a peed that will produce an angle B1 which

coincides with the blade angle B1bull At other gate settings

the vector v1 will rotate and change in magnitude in such a

9

t ehion that B1 will beoome either greater or 1 sa than B1bull Th1 give rise to tbe phenomenon term d shock loasft

If B1 1a greater than B1 the relative ent ring veloebull

ityt v1 will have a compon~nt opposing the forward motion

of the runner The shock loss could be typified bullbull that

occasioned by direct impact or the water 0n the blade- If

E1 is lese than a] the vector l will overshoot the blade

and the flow will tend to eddy around the forward portion

or the blade tip

The shock loss can then be either due to impact or

eddying flow Since the area norm 1 to the radius at outlampt

of the w1eket gftee is essentially equ 1 to the area normnl

to the rad1u~ at the inlet to the turbine runner the combull

ponents ot vl and vl perpendicular to ul will b approxishy

mately equal This leads to the conclusion that xxbull ~epresenting the shock vector 1 parallel to Ulbull

For either the impact or eddy case the trigonometric

law of $1nee leads tot

XX

bull ul - sin (Bi-Al) vl eln Bi

It it 1a assumed that the energy lost in the shock 1a

the Telocity head ot the shock component XX then

10

VELOCITY VECTOR DIAGIWI

TYPES OF SHOCK LOSS

xbull X

IMPACT BDDJ

XX 1a Teloc1t7 caponent ot shock

Figure 2 - ~bine Runner Vector Diagram$ and Shock Loss Diagrams

11

2 shock loss (XX gt2g

C =sin (BimiddotAl)Let (1)sin Bi

(UlmiddotCV1)2Then shock loabull (2)- 2g

For a given gate opening C ia a constant ranging

from about 14 to 10 For a well designed wheel it is to middot

be expected that C would be approximately equal to U1V1

at rated conditions ie at point of maximum efficiency

This point will occur in the neighborhood of 3~ to 78

gate opening for moat turbines For overgate conditions

the angle A1 becomes larger so the value of C would

decrease For gate openings below rated conditions t he

angle A1 decreases and C would decrease One could expect

a fairly uniform decrease in t he value of C as the gate is

closed from t he overgate position

The velocity v1 is approximately constant for any

turbine speed since the area and rate of flow both decrease

fairly uniformly However for a given gate opening the

velocity V1 will decrease with increased turbine speed

From the foregoing comments and equation (2) the

following trends can be established

(1) For constant turbine speed the shook loss curve

will be close to parabolic in shape concave upward and

have its maximum near t he point of complete gate closure

--

12

and its minimum near the rated gate position

(2) For conatant gate opening the shook loss curve

will approximate a symmetrical parabola with its vertex

the point of minimum loas located at the rated condition

of operation (7 Pbull 79)

c Exit Loas

It can be seen from Figure 2 that the exit loss from

the turbine would be v222g if no draft tube were present

The addition of a draft tube permits the gradual reduction

of velocity by an increase in cross sectional area between

the exit of the runner and the exit from the draft tube

The exit loss and the frictional loss encountered in

the draft tube may be placed together in the expression

m va2 (3)Exit Loss ~---2g

For the ideal case of no friction in the draft tube

m is equal to the square of the ratio of the area at exit

from the runner to the area at exit from the draft tube

In an actual turbine installation however friction

will change the value of m (7 p 84-85) to somewhere

between that for the ideal case and a maximum ot 10

In the interest of maintaining a minimum exit loss

the turbine should be designed and operated so the velocity

V2 will be minimum This will occur when the discharge

13

vector is at right angles to the tangent to the runnerbull

ie the angle A2 1e ninety degree bull It ia to be expected

that this condition will be tultilled near the design con~

d1t1ons ot the ~bine

Current design praetiee 1 to have a small component

ot v2 in th$ direction of turbine rotation at rated condibull

tion$ ltS p 938)

For a constant turbine speed the d1seharg or exit

loss is ess nti lly a constant

For a constant gate opening the exit lo s curve is

aptrroximately a symmetrical pa~abola with ita vert x the

point or minimum loss located at a slightly lowe~ speed

th n the turbine rated speed (7 Pbull 79)

Chapter III

PROPOSAL OP ALlERMAlE MFTBO 0 CO TROL-A lz ~ Location 2 Control

Thua tar only practice and theoretical aspects appemiddotrbull

taining to present day turbinea have been d1acuaaed It

haa been presented that control over the ~bine ia ezerbull

oiaed b y manipulation of the wicket gatea located 11101led1bull

ately preceding the runner These gate - upon rotation

modify both the magn1tu4e and the direction ot the entering

velocit7 Moreover it has be n shown that a simultaneous

change in these two variables leads to inefficient operabull

tion by the introduction of shock loss he farther the

point of operation a from the rated conditione the more

aerioua ia the ahock loss encountered

Any attempt to better turbine pertorance at other

than rated conditione and tbne flatten the top ot the

etticieney hill8 must concentrate upon the lessening ot

the ahock loaa It 1a a aumed that 1 provement in the

scroll case gates and runners would lequ1re sueh pertecbull

tion 1n machine work and metal$ as to be prohibitively

expensive

It ie surmised that any move to elblinate eYen parbull

tially the shock loss would require separate control ovel

l$

the flow and gate exit angle Since it is improbable that

d1~ect1on could be controlled at any location other than

where the gatea are situated in current turbines it will

be assumed that guide vanes will be necessary regardlesa or the method used to control the rate of flow

The primary purpose ot th se guide vanes 1s that or control over the direction ot the incoming water They

should be free to rotate in much the same manner as ordibull

nary wicket gates in order to exercise control over th

turbine speed

If the rate ot tlov is to be controlled elsewhere it

must be modified either in the penstock or the draft tube

Devices that could be used are standard valves gates

variable orifices variable venturi sections and associated

flow regulating schemes

Alauming it were decided to locate such a device upbull

stream of the turbine it would be necessary to allow disbull

tance tor the flow picture to become reestablished prior to

entry to the turbine A contused flow making transit of

the turbine passages would only contribute additional loesbull

ea Such a distance allowance would be perbapa 20 to So

diameters (2$ Pbull 119-123) In large penstocka th1a would

repreaent a considerable distance Which from the viewbull

points ot convenience and control would be undesirable

Attempts to ascertain the effect or additional tlov

16

reduc ion at the wicket gatctsmiddot wae ade 1n the lfadraulioe middot

Laboratory of Oregon St middot te College in 1933 (20) Three

d1tterent thode ot reducins the tlow were t~ied

(l) Locking in the cloeed position pairs or wicket

gatea located opposite to eaeh o~er on the -periphery ot

the wheel

(2) Locking adjacent gates in an open position by

inserting blocks of wood between them and

()) Suocess1vely looking adjacent gates in the closed

position

The results indicated a arked reduction in both power

and efficiency when compared to the curves tor normal gate

operation However it was demonstrated that it was poae1bull

ble to ahitt the power and tfieiency curve ill relation to

turbine apeed lbis important feature will be diacussed

later

ihe main conclusion of the investigation was that conbull

trol by the conyent1onal wick t gates was auper1or to other

methode egtt control exercised at the gates the aelvebullbull

It would app$ar that the bebullt location tor flow conshy

trol would be in the draft tube since none of the objecbull

tiona prev1ously mentioned wou~d eziat there

As bas been stated previously the sole object or the

17

18

turbine is to produce power as etfic1ently as possible

The equation tor the power output of a turbine () Pbull 227)

PaWHe HP (4)55o bull bull Assuming the head 1a constant and a g te located in

the draft tube decreases bhe rate ot flow the power eu

only be increased if the etticiency increases

The ettective head Gn the turbine 1s conventionally

d r1ned as the difference between the auma ot the elevashy

tion head pressure head and velocity head at the entrance

to the turbine casing and the tailrace ($ Pbull 872)

lt ie recognized that the theoretical treatment ot

shock loss as given is highly approximate and serves only

to dictate certain trenda For example the area at xit

rom the wicket g tea CfUl be measuPed with some exactness

but there exists no guarantee that the wateP particles will

complet-ely fill the apace oz- will exit at the establiahed

g te angle The same can be said of the exit trom the

runner blades AssUIlptiona were implied which would indishy

cate that all water particles passing a given croea section

ampH traveling at the same velocity in the same direction

the e alone are autt1c1ent to show 11m1tationa in a theoretbull

1eal approach to the problem

Assume a turbine with ordinary wicket gates tor oonbull

trol compared gainst the same turbine with a gate in the

18

draft tttbe tor supplampment1ng control or the rate ot rlow

Let it also be assumed that the two turbines are opershy

ating at the same point It 1s desirable to predict relabull

tive performance of the two turbines 1 this point of

operation is such that edd7 s hook loss ot reasonable proshy

portions is present in the fir t turbine

~ tull erteot of the shock loss will be exper1 need

by- the fir t turbine

lhe second turbine will derive certain advantages 11

the gate in the draft tube is adjusted to reduce the tlov

1n the proper amount Since they vary a the square ot

the veloo1t7bull the lossabull in the aeroll case wiomiddotket gate

and runner passages will decx-ease aetet-r1ng to Figure 2 1

it can be seen that a decreased velocity v1 w-ill reduce the

eddy shock losa

The ent loss in the dJtaft tube of the second turbine

will be the sum ot the tr1ct1onal loss and the velocity

head at ex1t The velocity head dissipated will be greater

due to the closing action or the gate but the reduoed

t~ictional loss which ia a tunction ot the rate of tlow1

will partially balance this

It 1a entirely possible that the net reduction in

losses in the second turbine will lead to a greater ettibull

oiency and more power output than 4eYeloped by the first

turbine

19

In Figure 3 the plot ot power output against turbine

speed for Curv A~ represents the typical family of curvea

tor a reaction turbine Th b st sp ed is the locus ot

points connecting maximum eft1oiency at each gate opening

The operating speed is the coZUJtant turbine apeed which

passes through the point ot maximum efC1ciencr of the turbull

bine The plot of turbine efficiency against power output

for Curve A is also ahown

It the turbine with flow regulation in the dratt tube

oan demonstrate superior power and efficiency at part loads

the effect would be the same as a shifting or the power

curves toward the condition shown fop Curve B 11 Thisbull

illustrates th ultimate case of the uperpoait1on of best

and operating speeds It will be noted that the pet-form~

of the turbine ot Ourve Bu 1a better than that of CUrve

A at part loads because of ita ability to sustain a relabull

tively high etticienoy ovel a Wider range of power output

o Reguireaegts tort Test Velitication

It is desired to deterra1ne the effect on the turbine

performance b) the addition of a gate in the dratt tube

Th step in the teit will bet

(1 To determine the power output and efficiency ot

the turbine tor wicket gate settings above and below rated

conditione for a wide range ot speed

20

CURVEAbull

TURBINE SPSBD TURBID SPEKD

POIBR OOTPOl

Figure 3 - Turbine Performance Curves

21

22

(2 peat (l) with the gate installed in the drat

tube

(3) middot Converting middot all data to a constant head compare the

powere and effioiencies at the same wicket gate setting and

turbin speed tor the two cbullses

If the ddition or the gate indicates an improvement

in power output and efficiency and the powe~ curve shifts

to the right along the turbine apeed scale the advantage

ot draft tube con~ol of the flow will hav been demonshy

strated

Chapter IV

A E9J11pment

ih turbine used in this test is lJ 5 1nch Pelton

reaction turbine with a rated output ot 30 horsepower under

a head of 56 feet at a speed ot 720 reYolutiona per minute

Views of this turbine are hovn in Figures S and 6 The

turbine is installed on a concrete pad located over an open

channel in the Hydraulics Laboratory at Oregon State Colshy

lege The date of manufacture of this turbine was 1915

The water was delivered to the turbine from a sump

reservoir by two pumps operating 1n parallel Each pump 1a

an 8 inch Pelton double suction centrifugal pump witb a

rating of l$00 gallons per minute at a head ot 75 teet with

a speed ot 1175 revolutions per minute Tbe inlet tlange

ot tne turbine is $pprox1mately 18 feet above the center

line of the pump

A direct current generator was coupled to the turbine

to receive tne power d veloped as shown in Figures 4 and 7 The generator is a Spr gue Electrodynamometer rated at SS horsepower with a speed range of 7$0 to l$00 revolut1one

per minute The classification is type LO 26A 2)0 volta

Figure 5 - View of Test Turbine

Figure 6 ~ View of Test Turbine

and 149 amperes lbe generator ti ld was aepar tely

excited using direct current from a motor g n r tor ampt

(l$ p 4~8)

The power output of the generator waa dissipated in

the water rheostat (3 p 488-489) shown in Figures 9 and

10 The galvanized tank contain d water ot variable d pth

on an electrode ot cast iron m aauring 1bull x 1 x 1

In the initial installation of the turbine it was

intended that the power output should be measured with a

Prony brak bull For th purpoa68 or this teat it was decided

that the brake was too instable and the generator was

substituted The platform for raising the generator the

nee asary two teet for alignment was built out of available

material In this case heavy laminated wood blocks reiashy

torced with other timbers were used and bolted through the

concrete deck (11 Pbull 36-$7)

Due to the light concrete deck the lack ot mas in

the platform and the slight misalignment in the flexible

coupling ao e vibration waa encountered It seemed to

ncr aae linearly to a maximum at the speed of bout 750

revolutions per minute Above this speed no vibPation was

noticeable The vibration waa not se~ere and does not

appear to have materially affected the test results

26

B Intrumentat1on ~ eaeur1ng Devices

The pressure head at inlet to the turbine vaa meaave4

bymeane ot two )6 inch waterbullmeroury manometerbull connected

in series as shown in Figure 8

The terminal voltage ot the generator vas meaeured by

a laboratory voltDleter with a range to )00 yolta and callbull

brated to within 15 Yolta

The armature current bull and hence the line current was

measured by a laboratory ammeter with a range to 150 amperea

and callbrated to w1 thin o 7S amperes

Tae rate ot tlow was established by weight and time

meaeurementa The weighing ank has a capacity ot 121 000

poundsJ the weight belng indicated by Toledo direct reading

scales Timing was done with a hand atop watch with clivibull

aion ot 02 second

he ~ater level in the tailrace was dete~1ned by a

hook gauge lhie was read to the nearest 001 toot

The turbine and generator speeds were eaaured by a

hand tachometer The technique of almost cont1nuoua readbull

ings of the speed gave an error ot no more than 5 revolubull

tiona per minute

c Operational Procedure

Atter the water level in the aump was checked to

insure an adequate auppl7 the puapa were primed and

27

Figure 7 - Test Generator and Plattorm

Figure middot8- Instrument Board and Field Rheostat

28

started After venting they were valved for operation 1n

parallel

The motor generator set was started to supply the

field current and the circuit breaker was closed Water

wa added to the water rheostat to the level shown in

Figure 10 ~ field current wae minimized by cutting in

all the f ield resistance in the field rheostat of Figure 8

The l2 inch gate valve shown in Figures 5 and 6 waa

slowly opened and the turbine and generator brought up to

speed The 12 inch gat valve and turbine were vented and

the pumps were checked to insure neither had lost ita prime

lhe water rheostat offers very steady load 1f the

water level is essentially constant and the water temperabull

ture 1a fixed () p 488~89) In order to maintain this

constant temperature it was decided not to circulate the

water in the rheostat but rather to allow the water to

boil thua achieving the desired result A standing wave

was set up on the face ot the electrode by the boiling

action but a atable load was eatablished except at very

low water leYels where th11 agitation led to fluctuationa

in the line current

After putting the turbine and generator on the line

maximum power was dissipated in the rheostat by redueing

the turbine speed to between oSO and Soo revolutions per

minute Salt vas added to the rheoetat wat r to increasemiddot

29

Figure 9 - View of Water Rheostat

Figure 10 - View of Water Rheostat

Separate Field ExcitationFrom Motor-Generator set Compound Water-Mercury

---shy

re Manometer

I Q)

~ 0

~

Book Gauge

Open Channel

I

Slap Reservoir

Figure 11 - Wat~r Flow Diagram and Electrical Layout

31

waiting pe~iod ot perhaps an h~ followed

while the boiling point or the water wbulls reacbe4 During

this ti+ne the manometer was vented end eheoked electrical

measur1ng 1nstlUments were connected end the hook gauge was

adjusted tor elevation

It required about two- houtte tor the generator to reach

its normal operating tempe-ratu~e_ After the water in the

rheostat and generator had reached their operating temperabull

turea it was possible to begin the taking of data

The only vaPiable which was controlled wee the turbineshy

generator speed However the upper l1ut1t of safe line

current was slightly over 100 ampJilPampPes and the eireuit

breaker would open when the current reached lOS ~ere bull

Control was exercised by means ot regulating the water

level and salt 1n the water rheo tat and the res1stsnoe of

the tield rheost t~

The etfeet ot each type ot regulation on the three

variables is shown below

Volta Aaperebull Speed

Inc Dec Inc Dee~ Inc Dec

Wa~e1 Level Inc Dec~ X

X X X X

X

Salt Concentration

Inc Dec X

X X X X

X

field Resistance

Inc Dec

X X

X X

X X

32

Jlot all methods gave the ame amount ot change in a

given variable and a period of experiment and trial led to

the following scheme starting the rune with the lowest

turbine speed the water level was high with a high amount

ot salt and the field resistance was cut completely out

Aa it became necessary to increase the speed tor each

aucceasive run either cutting in t he field resistance

decreasing the salt concentration or lowering the Vater

level would produce the desired result However decreasbull

1ng the salt concentration had to be done Without a net

gain in water which led to a tluahing procedure that was

not particularly good because cold water was introduced

which required time to heat to the boiling point Cutting

1n additional field resistance was a good method but th1a

increased the amperage possibly to the point of opening

the circuit breaker Lowering the water level was aatiashy

factol1 until the level got too low causing the current

fluctuation previously mentioned Actually it turned out

that a combination of lowering the water level and cutting

field resistance in would carry the speed from ita minimum

to 1ts maximum value it the proper choice were made each

time the speed waa to be changed At the conclusion of

each aet of runs at a high speed the water level would be

low and the field resistance high

33

TURBINE

PAD AND DECK

TAILRACE

WATER SURFACamp

CONCRETE

DRAFT TU1B INSERTS

7 5( DRAFr TUBE

FLltJI ARIA

5~ DRAFT TUBE

FLOI ARSA

Figure 12 - Sketch of Draft Tube and Test Inserts

34

Figure 13 - View of Draft Tube Insert

Figure 14 - View of Draft Tube Insert

D c __ ~s_middot hedu_le of

A number was assigned to each run The fi~st number

applies to the draft tube tlow areas

1 bull 100~ flow area or 0~ oonatriction

2 - 7S tlow area or 2$ conatr1ct1on

3 SoC flow area or so~ constriction

The second number refers to the wicket gate openings

9 over gate opening

6 bull intermediate gate opening

4 bull one h lt gate opening

The third number 14entif1ea the location of the particular

1Wl in a set ot rona made at a given dratt tube tlow area

and wicket gate opening

fnua run number 1bull4bull10 would identity this as the

tenth run ot a set made at halt gate with 75 ot the draft

tube t1ow area

Rune w re made tor a g1yen dratt tube condition

Firat tor tull 41-aft tube flow area seta ot rune were

made for the overgate halt gate and intermediate gate

conditione An insert was placed in t he draft tube and

rune based on the same gate conditions were made tor the

7S~ draft tube flow area case The insert was then changed

to allow only $~ draft tube flow area

The inserts are sketched 1n Figure 12 and photographed

ln Flgurea 13 and 14 They oonaisted of circula~ segments

36

or l2 ineh plywood mount 4 on wooden legs 10 inches high

The 1nse7te were placed in position and secured by th use

ot a-clamps on the legs and the outside ot the bottom of

the draft tube The obvious disadvantage to this method

waa the neoeasity tor draining the water from the tailrace

tor a change ot 1naert The advantage vas of course the

simplicity ot design and construction

Chapter V

DATA-A Original Data

The normal data-taking crew consisted or two men

Assuming adjustments having been made to secure a certain

turbine speed (aee section on Operational Procedure) one

man would take semi-continuous speed readings with the hand

tachometer until a state or rotational equilibrium was

reached This could be only a period or two minutes up to

ten or tifteen minutes As soon as steady speed was

assured the data taking would begin The second man went

to the weighing tank Where a minimum ot three weighingamp

were made The requirement was to get three consecutive

readings such that the ditterence between tbe smallest and

largest time did not exceed 04 seconds The time to

collect a given weight ot water was then assumed to be the

arithmetic average of the three times He then went to the

hook gauge determined the hook elevation and then

recorded the data on the data sheets The first man meanshy

while had taken readings of the line voltage line current

and manometers and checked the turbine speed by multiple

readings During the length of the run all values were

38

checked to determine mean values for recording

The minimum length of one run was about five minutes

If one or more measure ants tended to drift during the run

all values wer discarded and a new run began as soon aa

qu111br1um was stabl1shedo

B -0-al_e_u_l_a_t--d Data

The h d on the tu~bine 1 defined by

($)

The maxtmwm velocity V4 was equal to about o8 tampet per

secon4 which makes it a negligible quantity when converted

into velocity head

An engineerbulla level was used to deterine the d1ffePshy

ence 1n elevation between the compound water-mercury manoshy

meter and the hook gauge Using this value the equation

for turbine bead becomes

where z4 is the hook gauge reading

The rate of flow 1 cent

w weight or water collected average time to collect

The inlet velocity v1 vas calculated by dividing the

weight rate or flow by the specific weight of water and the

)9

area ot ~e inlet pipe This was equivalent to dividing

the weight rate of flow by 490 Then the power input to the turbine is equal to

WHpin rri

10 (6)

Also

(P ~ut) Turbine

(P out) + Generator

(P lost) Generator

The power output of the generator is simplJ the

produot ot the terminal voltage and the armature (line)

curPent The power lost in the generator can be subdivided

into copper losses and stray power losses lo evaluate

these cunes based on losses of an identical generator

11leampsured by the Department ot Mechanical Engineering were

used The loss curves are reppoduced in part in Figures

15 and 16

Determination ot generator losses proceeds as tollowau

(1) From Figure 15 detem1ne the vo1tage drop in the

armature circuit using the temperatures of 1220 F and the

meaaured current

(2) The induced voltage is t~e sum of the terminal

voltage and the voltage drop 1n the armature circuit

() Entering the induced voltage and the turbine speed

into Figure 16 the stray power loss can be determined

(4) The copper lose can be evaluated from Figure 1$

using the measured current and the temperatlll-e of 1220 P

40

25 ~------~--------~--------~------~

U) -U) - 20

f-4 ~

-~ -gt 0

0

VOLTAGE DROP

~ - i -

- bullbullbull bull - -middot-middot -+ ~- + -t--+ ~ - ~ middotbull ~-~ middott- -+----- _ -4 middotmiddot- --~-+-t---r~~ ~--+t-t- - ---t-c-++~-ulf--

0 50 75 100

Figure 15 - Curves of Generator Voltage Drop and Copper Loss

41

1200

1000

800

600

800

0

0

~-

middot--~ 1shy --1 + bull l

100

I -

150 200

IIDOOED VOLTAGB (VOLTS)

Figure 16 - Curves of Generator Stray Power Loss

_ j

-bullshy -L---- shy middot -shy

250

- r

42

(5) The generator los os equal the sum of the eopp r

loss and stray power loss

~e efficiency or the turbine is taken as

etticiency u e =P out (8)Pin

~ample pound Determ1n1gg turbine Power Output

The following data are taken trom that ot Run 1-9-1

Line voltage 1040 volts Line current 870 amperesSpeed 355 revolutions per minute

The induced voltage 1a determined as follows

Line voltage 1040

Voltage drop 90 using Figure 15 with line current of 870 amperes and temperature ot 122 degrees)

Induced Toltage 1130 volta

The power output of the turbine is determined as follows

Generator output 90$0 (line voltage z line current)

Oopper loss 7 (using Figure 15 with line current of 870 amperes and temperatUe or 122 degrees)

Stray power lose 470 (using Figure 16 with speed ot 355 revolutions per miDUte and induced voltage or 1130 volts)

Turbine power output 9527 vatta

or turbine power output 1s 12z2 horsepower

43

The conversion of the calculated data to a constant

head is based on the conventional assumption of constant

efficiency regardless of turbine head For a constant head

ot 81 teet a purely arbitrary figure the tollowing relashy

tionships are ass1lJiled to be true

I ____L (9) (i)l72

(10)

For these two values the specific a peed may be combull

putedt

N t Jt VPt (11)8 243

Chapter VI

~RESULTS

A -Pr_e_ae_n_t_a_t_t_o~n g Reaultbull

Graphical presentation ot the results ot this te1t

are given as follows

Figure 17 -Turbine characteristics with 100~ dratt

tuba 1low area

Figure 18 - Turbine characteristics with 7S dratt

tube tlow area

Figure 19 bull Comparison ot power and etticiency at

over gate conditions between 100 and

75~ draft tube flow area

Figure 20 bull COZQparison of power and ettic1ency at

halt gate conditions between 100~ and

7S~ draft tube flow area

Figure 21 bull Comparison of power and etticiency at

over gate condition between 100~ and

So dratt tube tlow area

Figure 22 - Comparison in variation ot apec1t1c

speed between 100 and 75~ dratt tube

tlow area

50

45

20

-bull - 1--shy40

bull J-~ 30

~ ex

~ 20

~~ ~ -)q

I

~ - _

- -

10~ OF DRAFT TUBE FL(Jif AREA

CONSTANT HEAD OF 8l FEST10

POIER OUTPUT EFFICIENCY SPECIFIC SPEED

0 ~--------------_--------~------~------~ 400 600 800 1000 1200 1400

TURBINE SPEED (RPM)

Figure 17 - Turbine Char~cteristics with 100 Draft Tube Flow Area

50

46

-bulllle

~ 7 ~ OF DRAFt TUBE FLOW AREA

0 -~~-rl C05STAMT BEAD OF 81 mET 1J~

POIER OOTPUT ---+- ---o ~_H EFFICIDCY ~ I shy

bull ql SPECIFIC SPEKD - ~ -

bull ~ J 10 L rmiddotr- r- -

bullz- I

~~ 30 ~~--~----~~-

20 ~ ~ middot-shy

26

~~ 25

~0 ~r-----i (

Tbull -bullshy

400 600 800 1000 1200 1400

TURBINE SPEED (R PK )

Figure 18 -Turbine Characteristics with 75 Draft Tube Flow Area

47

EFFICIENCY 60

1-----shy

-~ 50~--~--~~-~middot middot middot middot r~-~----~~~~---4~-r~-~~gtt

II

POWER~ J ~ bull bull

u I

sH

40~------+-------+---- -~~--~~-~~~~

~----~rl 1 bull

I

I

0~--------------~------_------~--------

~ -OVER GATE CONDITION

COIJSTANT HEAD OF 81 FEET

0 o 10~ DRAFt TUBE

_-- _ 7~ DRAFT TUBamp FLON AREA II

10_~-----+--------r-------r----~~

400 600 800 1000 1200 1400

TURBINE SPEED (RPM)

Figure 19 middot - Comparison between 75 and 100 Draft Tube Flow Areas of Power and Efficiency at Over Gate Conshydition

48

t

bull --4 r ~- ~ middot~

70 1-----------+-~~~~~+middot ~ ~~ middot middot -~~--~~--------~~----~-+1

-~-

Atbull bull

lla-

60

amp0

40

20

10

oampOO

t _ - - ~-+- - -~-

l2 GATB COJIDITIOJJ

COJISTABT HJW) OF 81 JBET

o 0 lOQ( DRAFl TUB8 FLOI AREA

e-- - e 75 DRAFT TUBE FLOW AREA

800 1000

- r-

~

TURBIbull SPBIID (RPII)

Figure 20 - Comparison between 75 and 100 Draft Tube Flow Areas of Power and Efficiency at Half Gate Conshydition

49

60

50

-40

bull 30

IIQbull

20

10

0

400

- t - ~

EFFICIENCY

_J bull - bull bull

~ r r middot t -+ shy L -t -

OVER GAD COliDITIOI

CONSTABT BEAD OF 8l FBB

o o 10~ DRAFt TUBE FLOI ADA middot--- 5~ DRAF TUBE FLQPi AREA

600 800 1000 1200

Figure 21 -Comparison between 50~ and 100~ Draft Tube Flow Areas of Power and Efficiency at Ove~ Gate Conshydition

50

25

20

15

10

0

Figure 22

~- T -4 -t- -l --~-

t-~ I

middot --~- t ~---- _ __ _ + --

----~- --r-- --

~-=J-~-=-~ -==~ _ ~- -- ---f---1 - shy

CONSTANT HEAD OF 81 FEBT

o--o 1~ DRAFT TUBE FLltll AREA

75C DRMT TUBK FLCIJ AREAmiddot--middot-middot 600 800 1000

TURBINE SPEED (RPK)

Comparison of Specific Speeds for 75 and 100 Draft Tube Flow Areas

51

B Discussion 2 Result

Consideration of Figures 17 and 18 indicates the

overall eftioi ncy pattern or hill is significantly or

rounded for the 7$~ flow area than for the 100~ flow area

bia implies a greateP efficiency is possible at speeds

leas than or greater than design speed with an insert in

the draft tube However the muilDum efficiency is lemiddotas

Direct comparison at over gate conditions is made in

Figure 19 ~e same general trend is noted tor both the

etticiency and power curves for the 7$~ flow area case

The eurves show higher values at overspeed than do the

correaponding cWvea for the 100 flow area case It ia

not clear whether the curves have been shifted by the dratt

tube constriction or whether the curves simply bulge past

the normal curves at both overspeed and underspeed condishy

tions The power curves apparently peak near the aeme

point bullalthough maximum power is still obtained with the

normal draft tube area

For the comparison at halt gate operation shown in

Figure 20 a general improvement has apparently been made

by restriction of the draft tube flow area At every speed

the etticienoy and the power is greater for the restricted

tlow case The two ett1o1ency curves and two power curvea

are practically parallel throughout the speed range ot

teat

As the flou aroa i e decreased still farther a s1gn1

ticant change appears Reterr1ng to Figllle 211 tor the $0

flow area curves it a obvious that exit losses have

become excessive at the overgate condition because the

efficiency and power are everywhere leas than tor the case

of normal draf t tube area

Earlier it was pointed out t hat 1t the r esult s 1nd1bull

eated an increase in both power and ef tieiency- t hen it

could be assumed tha t the additional los s i ntroduced with

the draft tube insert is less than the diminished losses

due to leas shock losa and water passage losses For the

places where both the efficiency and power have been

increased we can assume that the insert has improved turshy

bine performance

For the places where the power haa been decreased

nothing can be said as to the elimination of ampbock loss

because the new lose present with the drat tube insert has

overshadowed any gains in eftecti Ve head upatJ-eam of the

insert

Near the peak of the efficiency hill howeve~ it may

be pointed out t hat shock loaa ie a minimum with a normal

draft tube and the insert merely adds an additional loss

with the resultant decrease in maximum efficiency tor the

7$~ flow area case

Perhaps the most s1gn1ticant set of eurves is shown aa

53

Figure 22 In this graph values of specific speed tor the

75 and 100~ flow area cases for both over gate and one

halt gate openings are plotted against turbine speed At

every speed and both gate openings the value ot specific

speed for th 75~ flow area case is greater than that for

the 100 t1ow area ease

Since the head is a constant for both situations this

may be interpreted in either of two ways trom equation

(11)

(1) For the same turbine apeed restriction of the

draft tube t1ow area resulted in greater turbine power

(2) For the same power amputput the turbine with 75~

draft tube flow area operated at a greater speed than did

the one with 100 flow area

Since the required diameter of a turbine varies

inversely with the speed the second interpretation could

be stated such that a smaller turbine could be used to

develop the same power output

Whether viewed trom the aspect of increased power

greater speed or reduced size the performance of the turshy

bine with reduced draft tube flow area is superior to that

with the nolmal flow are in the draft tube

The curve of specmiddotific speed versus turbine speed for

the so draft tube flow area case at over gate cond1t1ona

was not included in Figure 22 This curve lies below that

for the 100~ flow area c se at all speeds

In elaboration ot the second interpretation of Figure

22 attention is directed to the relative magnitudes ot

increased apee1f1c speed tor the two gate openings Assumbull

ing that the increase in specific speed implies a shift ot

the power curve to the right along the turbine speed scale

the power curve would be shifted more tor tbe halt gate

opening than tor the over gate opening

It thia trend could be extrapolated to the other gate

openings the tendency can be seen tor the line ot beat

speed to rotate toward the line of the operating speed as

illustrated in FigtU-e ) The advantage of this has already

been discussed

This particular turbine has a low specific speed tor a

reaction turbine Aa the rated value of apecitic apeed tor

reaction turbines increases the line ot beat speed departs

even more radically from the line of operating bullpeed It a

test similar to this were conducted on a reaction turbine

ot gleater specific speed it is pJobable t hat the rotation

ot the line of beat apeed would become more p~onounced

The scheme used in th1a teat had two obvious dr wbull

backs The first was the decision to leave all the wicket

gamiddottes installed tor all conditions ot the draft tube

These gates predominated in control of the tlow The

inserts added to the draft tube merely acted as auxiliary

55

contrGla

The aecond drawback was the choice or device to place

in the draft tube The reasons foll selection of this type

of device have been previously mentioned It is to be

anticipated that adaptation ot dratt tube flow control

would result 1n a better device for an actual turbine

installation Such apparatus might take the form of a

pneumatic bladder or a h7drau11oally operated variable

venturi section in the draft tube It is conceivable that

the gate as used in this test might be adapted also

Chapter VII

OONCLtJSIOfS

From the results of this test the following eonolubull

e1ona aa to the effect ot a variable draft tube flow area

on the performance or a r action turbine may be drawn

(1) The effect ot a variable draft tube tlow area 1a

generally favorable upon the operat1Gn ot a reaction turbull

bine because or the tendency tor the line or beat speed to

rotate toward the line ot operation This resulte in

better performance of the turbine at partbullloads

(2) he etf1o1ency eh111 tor the turbine beeomaa JDore

tlat at the top leading to a smaller max1JilWD effic1enc7

but e reater etticieney at other pointe of operation with

the insertion ot an auxiliary control ror the rate ot tlov

in the draft tube

(3) The power output of the turbine will increase at

over speed over gate conditione as well a at part gate

conditions with the proper amount or draft tube eonatr1cbull

tion or flow

(4) It is possible to eliminate at least partially

eddy type shock loss by tho introduction ot flow control

in the draft tube

BIBLIOGRAPBl

1 Addison Herbert A treatise on applied h-draul1cs New York Wiley 1954 724 Pbull

2 Allen o M and I A Winter middot Co111parative testa on experimental draft tubes Tranaact1ons ot the American ociety ot Civil Engineers 87t893bull970 1924

3 Barrows a E Water power engineering 3d ed ew York McGraw-Bill 1943 791 Pbull

Bovet G A Modern trenda in hydraulic turbine design4middot in Europe Tranaactions of the American Society ot Mechanical Engineera 75975bull993 1953bull

s Oreager William P and Joel D Justin Hydroelectrichandbook 2d ed New York Wiley 19$0 1151 Pbull

6 Daily Jamea w Hydraulic machinery Int Hunter Rouses Engineering hydraulics Hew York Wiley 19$0 p 8$8bull99

Daughertybull Robert L Bydraulie turbines ew Yorkbull7middot MoGrav-Hlll 1920 281 Pbull

8 Daugherty Robert L Inveat1gat1on of tne performance ot a reaction turbine ~anaactiona or the American Society ot Civil Engineers 7811270bull1304 1915

9 Davie L M Model and prototype testa Int Trend in hydraulle turbine practice symposium lranaactions ot the American Society ot Civil Engineers 1o63S3middot368 1941

lfJ Doland James J Hydro power engineering Hew Yorkbull Ronald 1954 209 Pbull

11 Gandy Theodore s and Elmer c Schacht Direct curshyrent motor and generator troubles operation and repair New York McGraw-Bill 1911 293 Pbull

12 Gibaon Arnold H Hydraulics and ita applications5th ed London Constable 1952 813 Pbull

58

13 Button s P Component loases in Kaplan turbinebull and The prediction of efficiency from model tests Probull coedings of the Institution or Mechanical Engineers168743-762 1954

14 Knapp R T~ Oavit t1on mechanics and its relation to the d sign or hydraulic equip ent Proceedings or tne Institution ot Mechanical Engineers 166150bull16) 1952

15 Langsdorf Alexander s Principles of direct curHnt mach1nee 5th ed New York r~cGrawbullH1ll 1940 746 Pbull

16 Lsrner Chester w Characteristica of modern hydraubull lie turbines Trans e~ions of the ~~erican Society ot Civil Engineers 66306-386 1910

17 Linsley Ray K Jr and Jobulleph B Franzin1 Eleshyments of hydraulic enginebullring New York McGrawshyBill 19$5 $82 Pbull

18 Mead Daniel w Hydraulic machinery llev York McGraw-Hill 1933 396 Pbull

19 ead Daniel w Water power engineering New York McGrawbullRill 191S 843 Pbull

20 Mockmore Charles A Part gate operation at water turbines Corvallis Oregon State College Department ot Civil Engineering 1933 11 numb leaves (Unpubshylshed typescript)

21 Mockmore Oharles A Flow characteristics in elbow dratt tubes Transactions of the Amez-ican Society ot Civil Engineers 103402middot464bull 1938

22 Moody L F Hydraulic machinery In c v Davis Handbook ot applied hydraulics New York McGrawshyHlll 1942 1082 Pbull

2) Ptau At-nold Hydrbullulie turbine handbook ld ed Milwaukee AllisbullOhalmers ManufactUIing Company 1948 70 Pbull

RheingalUI w J Recent developments in Francis turshybines Mechanical Engineering 74189-196 1952

25 Russell George E Hydraulica 5th ed New York Henry Holt 1942 466 Pbull

26 Safford A and E P- Hamilton American mixed tlow turbine and ita setting Tranampactions or the Amerieal Society of Civil Engineers 851237bull1)56 1922

27 bull Spannhake W1lhe1Dh Problems or modern pump and tur b1ne design Transactions of the American Society of Mechanical Engineers 56e22$-248 1934bull

28 Sutherlandraquo R A Better ethod or representing and middot tudying water turbine performance ~ansaetions ot thmiddote American Society of Mechanical Engineers 68t675bull 686 1946

29 Teats ot five models or draft tubes tor turbines Engineering News-Record Pbull 182-184 Aug 2 1923

30 White w M American hydztaulic turbines Mechanical Engineering S2t390bull39S 1930bull

31 White w M lhe hydraucGne rega1ner1 its developmentand appl1eat1ons 1n hydroelectric plants Meohanlobulll Engineering 43t37Sbull380 1921 middot

32 Winter I A Economic principlebull in designbull Int Trend in hydraulic urbin practice bull a ampoeiumTranaaot1ona ot the American Society ot Civil Engineerslo6332bull3S2 1941

33 Wiel1cenua G F Fluid mechan1ca or turbo-machineryNev York McGraw-Hill 1947 613 Pbull

APPENDICES

c

Appendix A

NOATIOB

A Angle between the absolute velocity vector and the tangent to the rwmer Subscripts 1 and 2 refel to entrance and exit ot the runner blade

B Angle between the relative 1elooity vector and the tangent to the rwmer Subscripta 1 and 2 refer to entrance and ezit or the runner blade

Angle between the tangent to the runner blade tip and the tangent to the runnel- Subscripts 1 and 2 reter to entrance and exit of the rt1rmer bladebull

Blade angle-gate opening conetant defined by equation (1)

e 09erall efficiency

g Gravitational acceleration assumed constant at 322 teet per second per second bull

H Turbine head detined by equation ($)

m Exit loss coeft1e1ent

Turbine speed expressed in revolutions per minute

Turbine speed under a constant head of 81 teet

specitic apeed of the turbine under a constant head ot 81 teet

p Power output in horsepower ot the tvbine

Power output of the turbine Ulder a constant head ot Sl teet

Pl- Pressure head at entrance to the tUlb1new

l1 Peripheral velocity ot the runneP Subacr1pta 1 and 2 refer to entrance and exit ot the JUnllampr blade

62

v Relative velocity reaulting trom the combination ot the absolute water velocity V and the runner periphshyeral velocity u Subscripts 1 and 2 refer to entrance and exit ot the runner blade

v] Relative velocity vector necessary to produce a tanbull gential entry into the runner blades

V Absolute water velocity Subscripts l and 2 refer to entrano and exit ot the runner blade

v2 Velocity head Subscripts 1 and 4 reter to the ~8 entrance to the turbine and the tail~ace wate~

w Unit weight ot water assumed constant at 624 pounda per cubic toot

V Weight rate ot flow in pounds per aeooncl

XX Velocity component ot ahook See Figule 2

Z Elevation head Subscripts 1 and 4 reter to entrance to the turbine and the taibace water surfacebull

Appendix B ORIGINAL DATA-Run

lfwnber

0-4-1 0-4-2 0-4-3 o-4-4 o-4-S o-4-6 0-4-7 0-4-8 0-4-9o-4-lo o-4-11 o-4-12 0-4-13

o-6-1 o-6-2 06-3 o-6-4o-6middotS o-6-6 o-6-7 o-6-8 0-6-9 o--6-lo o-6-11

Speed

rmiddot2middotbullmiddot(1)

336 38$ 451 S$9 620 669 6lt)$ 120 787 860 932

102imiddot109 bull

352 355 443middot 543middot 620 654AJs32

911 1001 1111

~essure Head rt (2)

410 410 416 426 431 43-7 439 44-9 452 467 482 soo $1 bull $

350 351 35middot7 )66 37-9 37-9 392 41 bull 3 43middot3 460 489

Elevation Bead

fjj $7 $7 $7 $7 $7 $7 51 57 5-15858 $8 58 56 56 $6565656 51 575As5a

Velocit Head

flj 07 07 07 06 06 06 06 os 05 os0404 03

09 09 oa o8 o8 os 07 07 06 o~o

Total Head rt ($)

47middot4 4A44 o 489 49-4 soo $02 $11 $14 $29 5imiddot45 2 576

41 bull $ 416 421 430 44middot3 44middot3 456 47-7 496 523551

Plow

lbtjec

326 324middot317 311 306 30029middot28 middotmiddot middot 386 275middot260 240 218

359 36~35 bull 349 345middot 339 330 318 300 273 240

Line Potential

vyqjbull 1060 1220 ~-0o 1920 2150 2000 2$60 2000 1940 18)015io11 o

1000 1100 139bull5 1760 1925 16$0 1620 1610 1540 1330 870

Line Current

amlscs 960 900 830 740 730655 70bull 0 530 660 600 5imiddot54 6 )60

982 930 860 780 ~3-545

79-5 74-5 670 560 370

P

Appendix B ORIGINAL DATA (Continued)

Run Number

Speed

Pbulltmiddotbullmiddot )

leasure Head ft(2

Elevation Head tt(J)

Velocity He-dfmiddotj

Total Bead tt($

Flow

lbstsec( )

Line Potential vo~ta( )

Line Current

amjs (sect

0bulllt)-1 0-9-2

3ll6 398

28o ~~1

$6 56

1o 10

346 347

390 365

1ooo 1190

aao 835

0-9-3 0-9-4 o-9-S

472 565 632

292 305 312

$6 s6 56

10 o9 o9

)$8 J7~o 37~7

381376 37o

1)6614oo 141o

820 ass ass o-9-6 0-9-7 0-9-8 o-9-9 0middot9-10

680 120 762 844 920

)24337346 366 390

56 $6 56 57 $7

09 os o8 oa 07

)89401 410 431454

367~ 357348 34o 322

1400 1J6o l36o 1310 1170

843 820 7957So 67~0

0-9-ll 0-912

1001 1100

41 bull 7 45-3

s 7 6~0

06 os 480 $18

299 268

980 65$

560 36~5

1-4-1 1-4-21-4-l1-4shy1-4-5 1-4-6 l-4-7 1 4-8 1-4-9 1-4-10 1middot4-ll 1-4bull12

354middot452 562 62q 674shy102 752 760- 863 932

1022 1100-

)82389 4014oa 416 41--7 423 428 44-2 45-7 486 49-2

51S757 51 5-7 5middot15zs sa $8 58 59

07 07 06 06 06 06 06 os o bull o 04 o J

446 45-)46middot4 471 ti7-9480 q86 491505 $19 548 55-4

)28 320 311 306 300 295 291 286 269 2582iimiddot21 bull

1080 14Lo 1550 153-5 1470 141-0 1385 1310 1310 1230 1120 855

970855 875 91-0 94~0 975 966 995 860 77-S 610 4fo

0 ~

Appendix B ORIGINAL DATA (Contirmed)-Run Speed Pressure Elevation Velocity Total Flow Line Line

Number Head Head Head had Potential Current rtjjmbull t~ bttec vyfs am~a12) ( ) ti fli 8

1-6-l $6 33$ $6 0bull9 400 364 1100 93 0 1-6-2 41 34laquo2 $6 oa 406 JS7middot iios a5s l-6-3 500 3~0 5bull6 os 356 1 1 o aos 41middot~1-6~4 35bull4 5-6 oa 41middot 352 16~0 82 0 5~1-6-5 5 bull 36_2 Sbull6 08 42bull6 349middot 161 ~ 0 86~0 1-6-6 622 366 $6 oe 43bull0 345middot 158 0 88~$ 16-A 649bull 37bull1 56 os 43-S 342middot 1570 895 1~- 386 57 07 46-0 192 ) 125A44 333middot 1-6-9 3) 404 5middot1 07 468 317 1620 675 1610 911 42-4 5-7 o6 48-7 298 168 0 61 0 1-6-11 999 451 56 os Sl ll 276 ~2-0 530 1-612 1115 485 58 04 54middot7 238 90 )3 0

1middot9-l 355 279 56 10 )45 385 1040 870 1-9-2 399 28J $6 10 )49 38$ 1140 86 5 l-9-3 ~ ao 291 56 ~0 35middot1 J8J_ JJ6o 815 1bull9-4 579 303 56 09 )68 375middot J4JO 830 l-9bullS 40- 313 )6 09 31middot8 370- 1460 82~0 1-9bull6 679 2) 56 09 3 bull8 364middot 1670 710 l-9-7 682 319 56 o9 384 ) 62 1460 79 5 l-9-8 724 33middot5 56 o8 399 3$6 bull 1480 76 -5 1-9-9 762 34middot3 $6 0 bull 8 407 )48 14910 13middotS 1-9-10 833middot )60 5middot7 os 42$ 339 144$ 686 1-9-ll 926 39middot1 5-7 07 455 318 1290 600 1-9-12 1000 41middot3 0-6 476 298 1115 510$ ~ 1middot9-13 1105 452 s o4 $14 2$6 710 )10

~

Appendix Bt ORIGDIAL J (Continued)

Run Speed Pressure Elevation Velocity Total Plow Line Line Number Head ltead Head jlamp$d P()ten~ibulll Current

r~~~m ft ft lbs~seo voltattj rgj twimiddot t 1 t2gt lt3 ou t ( rt

2-9-1 384 289 S 6 10 35 5 1400 1170 810 2-9-2 443middot 29$ $6 ltimiddot9 360 379middot 11(0 87$ 2-9-J 536 30bull 3 sc 09 )68 374middot 1)40 84 bull) 2-9-4 571 306 $6 09 3~1 372 120bull 0 955 2-9-5 623 316 S6 09 J l )6S UJSo 77$ 2bull9-6 669 327 S6 09 )92 )61 1240 905 2-9bull7 712 )39 56 os 40-3 351 12(0 86 bull0 2-9-8 ~5$~ J48 56 oa 412 348 1290 81 bull ) 2-9-9 04 )63 56 oa 42-7 339 12ltJO 76$ 2middotmiddot9-10 8$2 376 5middot1 07 440 33~- ~ o 710 2-9-11 955 394 5-1 o6 457 300 1100 506 2middot9-12 1000 421 $7 06 48middoti 295 1020 $18 2-9bull13 110~ 463 56 05 $2 267 620 3~0

oshy0

Appendix Gt CALCULATED DAgA

Turbine Run Generator Generator Turbine Turbine Efficiency Turbine Turbine Specit1c

Number OutputKWlt21

Loa~Jes KWlol

Outut K bull (H)

Input RP 12)

middot Percentlt13gt

Speed r~Jmiddot(

0ltput HP ~1

Speed r-m

( 6) middot

o-4-1 0middot4-2 0-4-3 0-4-4 0-4-5 0-4-6 O-qmiddot7o-4-8o-4-9 0-4bull10 0-4-11 o-4-12

1018 1o9a 1220 1)62J40214oa1J4oo 1357 1320 1164 997 718

046 o59 071 092 096 1071oo 134 104 100 109 107

14261sso 17)01948 2008 20322011 1999 19 09 1708 14-84 11o6

281279 27-7 276 215 273271 268 268 26h 258 24-5

soa 555 62$ 705 7)1145 742 74-6714645 51s 45-1

440 sos 585 720 195 sso sao 9$$ 985

1065 1135middot 1230

318 357 319 416 422 419412 39middot9 378 324 260 191

102 12bull4 148 191 21bull 3 22o 233 249 24924middot9 238 221

0-4middot13 418 104 699 228 306 1300 117 18)

o-6-1 982 045 1376 271 $08 496 376 124 o-6-2 o-6-3 G-6-4o-6-5 0-6-6

1023 1200 13 73 J415 139h

051 0middot66 oaa ()bull 96 088

14-39 1696 1958 2026 1986

276 27middot4 273 278 274

$20 61 8 717 7)0726

q95615745 8)5685

390 ll5middot3 sos soo 490

127 170 218 243 2$$

o-6-7 o-6-8 o-6-9o-6-lo

1288 1199 1032 7-45

o9o 094 09$ 096

1846 1733 1511 1128

274 276 271 260

67S 629559 43middot4

980 1085 1165 1245shy

436 )83316 21bull 7

266 276 270 239

0-6-11 322 1oo 566 2141 2JS 1350 101 177 0 --4

Appendix C CALCULATED DAlA ( Continued)-Run

Number Generator Generator

Out2ut Losaes xw LW- 12gt (lO)

Turbine Out2ut

ltPlJ

Turbine Inat lfP Jig)

Etpound1e1ency

PireentDl

Turbine Sed x-~m( 1

Turbine OutEut RPJl)

Turbine Specific

SeeedrIbullntbull

( 6)

o-9middot1 0-9-2 0-9-3 o-lt)-4 09-$ 0bull9-6 0-9-7 0-9-8 0-9-9 0-9-10 o-9-11 0-9-12

aao 994

111$ 1197 1206 1180 11)21081 982 784 5-49 2)9

0middot45oss o6$ 070 07$ 0-77 (l77 or~ o s06o 8 096

123~ 1402 1$80 1698 17bulllS 168$ 16bull18 ~middot5430 1151 a~J4 9

24middotgt24middot3248 25~25 260 260 259 267 266 26middot1 2S2

sos 577 63-7 671 676 650 621 60036J4

327 178

$) 610AlO 3$

92S 980

102$ 1070 1157middot 1230 1300 137Smiddot

44middot4 soo 523 ssomiddot 540so6 46-5 432 368 274 18~8

J46 176 21-1 255 2802s_A 28 289 288 265 231 168

1-4-1 1-4middot2 1-4-3 1-4-4 1-4-5 1-4-6 1-4-7 1-J-8 1-4~9 1-4-10 1-4-11 1-4-12

10bull48 1231 13-S6 1397 1)821375 1))8 1303 1127 953 683) 51

048 067 o7A07 0 bull79 oa1 oss o bullao osa 0lt)0 096 099

J468 1740 1921 1978 1958 19$1 1911 lSSi162 1)98 1045

603

266 264 262 262 261 2512$7 2$6 24middot7 24-3 233 217

551 660 13middot3155 75-6 7~-97 middot4 72$ 67 51middotJ 44middot9 21middot1

475 605 A4220

875middot 910 970_

1000 1090bull 1166 1243 1330

5816

44middot444middot5 430 427 412 392 329 273 188 l0-7

117 101 204 22$ 2)7245 2562sa 257251 222 179

a-C))

Appendix Ct CALCULATED -DATA ( Ocntinued)

1-6middot1 1023 o$2 14-41 26S 505 41~6 26~

54middot5 13middot3l-6-2 1201 067 1boo 625 47-9 17shy~middot41-6bull3 1296 oA9 1 middot43 26 9 700 so5 20bull 4 l-6-4 l3j5 o 0 19~09 268 71bull3 A5o 514 222 1-6-5 1) 5 o81 19(gt4 271 725 51-5 238 l-66 1398 081 198) 27-0 736 8 S13 252~-middot l-6j 1405 083 199i 211 733 885 $middot06 2$9 l-6 13middot9~ 103 2amp 0 279 71 8 985~ 467 ~-69 1228 1 bull 02 17-SS 270 661 109$ 407 ~3~ l-6bull10 1025 100 lSll 26i 573 1175middot 27~S32middot~l-ampu 153 1-00 llft3 26 444 1270 22 24bull8 1bull6-12 294 100 52a 231 22 3 1360 95 172

1-9bull1 904 048 1275 2J4Z $28 S4$ 459 1$2 1-92 98$ oss 13-92 24middot4 57-0 6JO 49bull1 176 1-9middot3 1110 066 1$76 24middot9 63middot4 I2o 536 21-7 l--9-4 1187 072 1685 251 66$ 5 $$ bull 0 261 1middot9-5 llltJ7 1710 25middot4 67-3 93$ 536 28~20-671middot9-6 1186 o 8 1708 25-7 67) 980 $15 2691-9- 1161 oBo 1660 2$middot3 6$6 990 508 29-1 l~- ll-32 oB) 16sect0 2$8 632 1030 471 291 1-9bull9 109$ oa5 2$7 614 1075 29S~middot 0 4imiddot41-9-10 9~91 oas 262 S$1 1150~ 3 o 292 1-9-11 o9o u57 12JiO 21gt 26-77middot74

-45 26sect ~middot91-912 $69 091 sas 25 middot3 1)0$ 196 2J-8 1-9-1) 220 098 426 2)9 178 1390middot 84 16 6

0 0

Appendx C CALCULATED DATA (Continued)

Turbine Run Generator Generator lurbine Turbine Eft1e1eney Turbine lurbine Spee1f1c

Number Output Losses Outit Input Speed Output SPed middot k_-V KW R _ H_bull_P Percent r Thm HP rpm_ (9) tlo) 11) middot (12 _) (lJI ( ) (1$ (14)

2-9-1 9--46 055 1)62 258 528 580 164 2-9-2 1024 056 248 58 4 665 4 9 191iimiddot48 4~middot0 2-9-3 1132 067 05 2$0 641 795 52q 237 2-9-4 1148 065 1027 2$1 -~8 845 525 252 2-9-5 11 77 oso 16-83 253 6 910~ 522 270 2-9 6 1122 071 1600 251 622 960 47-5 2722-9-A 1092 015 1562 257 608 1010 445 2z12bull9- 1052 079 1514 261 580 1060 41middot7 2 2 2middot9-9 986 o82 ]429 26) 542 1105 372 277 2-9-10 915 086 1340 268 500 1160 334 27-6 2-9-11 638 087 972 254 )81 1270~ 229 250 2-9-12 )28 090 828 259 )19 1295 179 226 2-9-13 192 094 383 2$ 6 150 1370 7 3 152

-3 0

Page 12: The Effect of A Variable Draft Tube Flow Area on the

5

must operate at a constant speed or rotation even though _

the power demand ohangos In thiamp case the turbine nuet

be eap~able or producing a range of power output yet menshy

ta1n e eonetant speed

Speed regulation of the turbine iv accomplished by

means ot a governor (23 Pbull 24bull3-7) bull The contr-ol or regulashy

tion 1s indirect that i s the governor actually exereiaabull

control over the water in order to JJaintain e given speed

Co-ntrol over- the turbine end bence its speed and

power is the function ot a ring of movable wicket gates

located just upsttteam of the turbine runner These w1eket

gates 1n the process of opening and closing upon eeeh

0~1ar in a rotational manner actually control the amount

velocity and direction of tne water passing throu~~ them

C Draft Tubes

It has been found that the effeetive head on a reae

1l1on middotturbine is increased with the addi timiddoton of a draft tube

(3 Pbull 256bull264) Tne draft tube does thin by~

(1) Making a greater presaure d~op across the turbine

possible by the creation of a negative pressure at the

discharge or the runner and

2) DeoreaGing the k1net1e energy lost by increasing

the eross sectional area at exit

he draft tube permits the turbine runner to be

6

located above the tail race water surface without the

sacrifice of head However cavitation will cause pitting

of the turbine if the difference in elevation is too great

A common maximum elevation difference is 19 feet although

this figure is quite subject to modification between difshy

ferent installations (3 p middot 264-266)

There are many different types or draft tubes in use

today the choice or type being largely a matter or

economics (2$ p 368-370) A very common type particushy

larly among the smaller units is vertical with flaring

sides However the angle of flare is limited by the possishy

bility of separation of the flow from the sides In order

to achieve a certain discharge area the length of the tube

may be such as to require a great deal of excavation In

oases or this sort the cost of this excavation must be

balanced against a more elaborate design that does not

require as much excavation Other draft tubes in use

include the elbow hydracone and spreader types

Despite the differences found in construction and

design the draft tube must accomplish the desired objecshy

tives while offering a good hydraulic geometry to the flow

passing through it An inefficient draft tube defeats its

own purpose

Ohapter II

DISCUSSION ~ TURBINE LOSSES

A General

lhe head that 1a actually utilized by the turbine 1a

less than the effective bead as defined by equation ($) by

the amount that 1a lost due to mechanical and hydraulic

reasons

Mechanical loaaea are a function or the turbine 8p$ed

fhis ia not a lineaz- function but varies eomewhere between

N and N2 (3- Pbull 224)

Hydraulic losses encounteled in turbines ma- be subshy

divided aa to the location or occurrence (3 p 225-227) aa

fOllOW$S

(1) Penstock and scroll case

(2) Wicket gates

(3) Between wicket gates and turbine runner

(4) Runner passages

(5) Runner exit into draft tube

(6) Draft tube and

(7) At exit from the draft tube

The flow in the penstock scroll case wicket gates

runner passages and draft tube may be envisioned as

examples of flew in conventional pipes elbows and convergbull

1ng passages If this comparison may be made it could be

assumed that the losses encountered in these locations

would be proportional to vn ~ value ot N is normally2g

aesU111ed to be 2

he losses encountered between the wicket gates an4

the turbine runner and exit lossos are special cases which

will be discussed separately

B Shock toes_

The flow betwe n the wicket gat outlet and the runner

blade entrance is or particular 1nt rest because no direct

comparison vith common flow situations is obvious

Conaider the vector diagram (7 Pbull 7576) in Figure 2

The veetoo v1 is the absolute entering velocity of the

water and is fixed in magnitude and direction by the setbull

ting or the wicket gates The vector l11 1e the peripheztal

velocity of the runnel which tol any given turbine 1e

dependent only upon the turbine rotational speed The

combination of these two vectors ylelda the third vector

v1 which is the relative entering velocity ot the water

nere is only one setting ot the wicket gates for a

given turbine a peed that will produce an angle B1 which

coincides with the blade angle B1bull At other gate settings

the vector v1 will rotate and change in magnitude in such a

9

t ehion that B1 will beoome either greater or 1 sa than B1bull Th1 give rise to tbe phenomenon term d shock loasft

If B1 1a greater than B1 the relative ent ring veloebull

ityt v1 will have a compon~nt opposing the forward motion

of the runner The shock loss could be typified bullbull that

occasioned by direct impact or the water 0n the blade- If

E1 is lese than a] the vector l will overshoot the blade

and the flow will tend to eddy around the forward portion

or the blade tip

The shock loss can then be either due to impact or

eddying flow Since the area norm 1 to the radius at outlampt

of the w1eket gftee is essentially equ 1 to the area normnl

to the rad1u~ at the inlet to the turbine runner the combull

ponents ot vl and vl perpendicular to ul will b approxishy

mately equal This leads to the conclusion that xxbull ~epresenting the shock vector 1 parallel to Ulbull

For either the impact or eddy case the trigonometric

law of $1nee leads tot

XX

bull ul - sin (Bi-Al) vl eln Bi

It it 1a assumed that the energy lost in the shock 1a

the Telocity head ot the shock component XX then

10

VELOCITY VECTOR DIAGIWI

TYPES OF SHOCK LOSS

xbull X

IMPACT BDDJ

XX 1a Teloc1t7 caponent ot shock

Figure 2 - ~bine Runner Vector Diagram$ and Shock Loss Diagrams

11

2 shock loss (XX gt2g

C =sin (BimiddotAl)Let (1)sin Bi

(UlmiddotCV1)2Then shock loabull (2)- 2g

For a given gate opening C ia a constant ranging

from about 14 to 10 For a well designed wheel it is to middot

be expected that C would be approximately equal to U1V1

at rated conditions ie at point of maximum efficiency

This point will occur in the neighborhood of 3~ to 78

gate opening for moat turbines For overgate conditions

the angle A1 becomes larger so the value of C would

decrease For gate openings below rated conditions t he

angle A1 decreases and C would decrease One could expect

a fairly uniform decrease in t he value of C as the gate is

closed from t he overgate position

The velocity v1 is approximately constant for any

turbine speed since the area and rate of flow both decrease

fairly uniformly However for a given gate opening the

velocity V1 will decrease with increased turbine speed

From the foregoing comments and equation (2) the

following trends can be established

(1) For constant turbine speed the shook loss curve

will be close to parabolic in shape concave upward and

have its maximum near t he point of complete gate closure

--

12

and its minimum near the rated gate position

(2) For conatant gate opening the shook loss curve

will approximate a symmetrical parabola with its vertex

the point of minimum loas located at the rated condition

of operation (7 Pbull 79)

c Exit Loas

It can be seen from Figure 2 that the exit loss from

the turbine would be v222g if no draft tube were present

The addition of a draft tube permits the gradual reduction

of velocity by an increase in cross sectional area between

the exit of the runner and the exit from the draft tube

The exit loss and the frictional loss encountered in

the draft tube may be placed together in the expression

m va2 (3)Exit Loss ~---2g

For the ideal case of no friction in the draft tube

m is equal to the square of the ratio of the area at exit

from the runner to the area at exit from the draft tube

In an actual turbine installation however friction

will change the value of m (7 p 84-85) to somewhere

between that for the ideal case and a maximum ot 10

In the interest of maintaining a minimum exit loss

the turbine should be designed and operated so the velocity

V2 will be minimum This will occur when the discharge

13

vector is at right angles to the tangent to the runnerbull

ie the angle A2 1e ninety degree bull It ia to be expected

that this condition will be tultilled near the design con~

d1t1ons ot the ~bine

Current design praetiee 1 to have a small component

ot v2 in th$ direction of turbine rotation at rated condibull

tion$ ltS p 938)

For a constant turbine speed the d1seharg or exit

loss is ess nti lly a constant

For a constant gate opening the exit lo s curve is

aptrroximately a symmetrical pa~abola with ita vert x the

point or minimum loss located at a slightly lowe~ speed

th n the turbine rated speed (7 Pbull 79)

Chapter III

PROPOSAL OP ALlERMAlE MFTBO 0 CO TROL-A lz ~ Location 2 Control

Thua tar only practice and theoretical aspects appemiddotrbull

taining to present day turbinea have been d1acuaaed It

haa been presented that control over the ~bine ia ezerbull

oiaed b y manipulation of the wicket gatea located 11101led1bull

ately preceding the runner These gate - upon rotation

modify both the magn1tu4e and the direction ot the entering

velocit7 Moreover it has be n shown that a simultaneous

change in these two variables leads to inefficient operabull

tion by the introduction of shock loss he farther the

point of operation a from the rated conditione the more

aerioua ia the ahock loss encountered

Any attempt to better turbine pertorance at other

than rated conditione and tbne flatten the top ot the

etticieney hill8 must concentrate upon the lessening ot

the ahock loaa It 1a a aumed that 1 provement in the

scroll case gates and runners would lequ1re sueh pertecbull

tion 1n machine work and metal$ as to be prohibitively

expensive

It ie surmised that any move to elblinate eYen parbull

tially the shock loss would require separate control ovel

l$

the flow and gate exit angle Since it is improbable that

d1~ect1on could be controlled at any location other than

where the gatea are situated in current turbines it will

be assumed that guide vanes will be necessary regardlesa or the method used to control the rate of flow

The primary purpose ot th se guide vanes 1s that or control over the direction ot the incoming water They

should be free to rotate in much the same manner as ordibull

nary wicket gates in order to exercise control over th

turbine speed

If the rate ot tlov is to be controlled elsewhere it

must be modified either in the penstock or the draft tube

Devices that could be used are standard valves gates

variable orifices variable venturi sections and associated

flow regulating schemes

Alauming it were decided to locate such a device upbull

stream of the turbine it would be necessary to allow disbull

tance tor the flow picture to become reestablished prior to

entry to the turbine A contused flow making transit of

the turbine passages would only contribute additional loesbull

ea Such a distance allowance would be perbapa 20 to So

diameters (2$ Pbull 119-123) In large penstocka th1a would

repreaent a considerable distance Which from the viewbull

points ot convenience and control would be undesirable

Attempts to ascertain the effect or additional tlov

16

reduc ion at the wicket gatctsmiddot wae ade 1n the lfadraulioe middot

Laboratory of Oregon St middot te College in 1933 (20) Three

d1tterent thode ot reducins the tlow were t~ied

(l) Locking in the cloeed position pairs or wicket

gatea located opposite to eaeh o~er on the -periphery ot

the wheel

(2) Locking adjacent gates in an open position by

inserting blocks of wood between them and

()) Suocess1vely looking adjacent gates in the closed

position

The results indicated a arked reduction in both power

and efficiency when compared to the curves tor normal gate

operation However it was demonstrated that it was poae1bull

ble to ahitt the power and tfieiency curve ill relation to

turbine apeed lbis important feature will be diacussed

later

ihe main conclusion of the investigation was that conbull

trol by the conyent1onal wick t gates was auper1or to other

methode egtt control exercised at the gates the aelvebullbull

It would app$ar that the bebullt location tor flow conshy

trol would be in the draft tube since none of the objecbull

tiona prev1ously mentioned wou~d eziat there

As bas been stated previously the sole object or the

17

18

turbine is to produce power as etfic1ently as possible

The equation tor the power output of a turbine () Pbull 227)

PaWHe HP (4)55o bull bull Assuming the head 1a constant and a g te located in

the draft tube decreases bhe rate ot flow the power eu

only be increased if the etticiency increases

The ettective head Gn the turbine 1s conventionally

d r1ned as the difference between the auma ot the elevashy

tion head pressure head and velocity head at the entrance

to the turbine casing and the tailrace ($ Pbull 872)

lt ie recognized that the theoretical treatment ot

shock loss as given is highly approximate and serves only

to dictate certain trenda For example the area at xit

rom the wicket g tea CfUl be measuPed with some exactness

but there exists no guarantee that the wateP particles will

complet-ely fill the apace oz- will exit at the establiahed

g te angle The same can be said of the exit trom the

runner blades AssUIlptiona were implied which would indishy

cate that all water particles passing a given croea section

ampH traveling at the same velocity in the same direction

the e alone are autt1c1ent to show 11m1tationa in a theoretbull

1eal approach to the problem

Assume a turbine with ordinary wicket gates tor oonbull

trol compared gainst the same turbine with a gate in the

18

draft tttbe tor supplampment1ng control or the rate ot rlow

Let it also be assumed that the two turbines are opershy

ating at the same point It 1s desirable to predict relabull

tive performance of the two turbines 1 this point of

operation is such that edd7 s hook loss ot reasonable proshy

portions is present in the fir t turbine

~ tull erteot of the shock loss will be exper1 need

by- the fir t turbine

lhe second turbine will derive certain advantages 11

the gate in the draft tube is adjusted to reduce the tlov

1n the proper amount Since they vary a the square ot

the veloo1t7bull the lossabull in the aeroll case wiomiddotket gate

and runner passages will decx-ease aetet-r1ng to Figure 2 1

it can be seen that a decreased velocity v1 w-ill reduce the

eddy shock losa

The ent loss in the dJtaft tube of the second turbine

will be the sum ot the tr1ct1onal loss and the velocity

head at ex1t The velocity head dissipated will be greater

due to the closing action or the gate but the reduoed

t~ictional loss which ia a tunction ot the rate of tlow1

will partially balance this

It 1a entirely possible that the net reduction in

losses in the second turbine will lead to a greater ettibull

oiency and more power output than 4eYeloped by the first

turbine

19

In Figure 3 the plot ot power output against turbine

speed for Curv A~ represents the typical family of curvea

tor a reaction turbine Th b st sp ed is the locus ot

points connecting maximum eft1oiency at each gate opening

The operating speed is the coZUJtant turbine apeed which

passes through the point ot maximum efC1ciencr of the turbull

bine The plot of turbine efficiency against power output

for Curve A is also ahown

It the turbine with flow regulation in the dratt tube

oan demonstrate superior power and efficiency at part loads

the effect would be the same as a shifting or the power

curves toward the condition shown fop Curve B 11 Thisbull

illustrates th ultimate case of the uperpoait1on of best

and operating speeds It will be noted that the pet-form~

of the turbine ot Ourve Bu 1a better than that of CUrve

A at part loads because of ita ability to sustain a relabull

tively high etticienoy ovel a Wider range of power output

o Reguireaegts tort Test Velitication

It is desired to deterra1ne the effect on the turbine

performance b) the addition of a gate in the dratt tube

Th step in the teit will bet

(1 To determine the power output and efficiency ot

the turbine tor wicket gate settings above and below rated

conditione for a wide range ot speed

20

CURVEAbull

TURBINE SPSBD TURBID SPEKD

POIBR OOTPOl

Figure 3 - Turbine Performance Curves

21

22

(2 peat (l) with the gate installed in the drat

tube

(3) middot Converting middot all data to a constant head compare the

powere and effioiencies at the same wicket gate setting and

turbin speed tor the two cbullses

If the ddition or the gate indicates an improvement

in power output and efficiency and the powe~ curve shifts

to the right along the turbine apeed scale the advantage

ot draft tube con~ol of the flow will hav been demonshy

strated

Chapter IV

A E9J11pment

ih turbine used in this test is lJ 5 1nch Pelton

reaction turbine with a rated output ot 30 horsepower under

a head of 56 feet at a speed ot 720 reYolutiona per minute

Views of this turbine are hovn in Figures S and 6 The

turbine is installed on a concrete pad located over an open

channel in the Hydraulics Laboratory at Oregon State Colshy

lege The date of manufacture of this turbine was 1915

The water was delivered to the turbine from a sump

reservoir by two pumps operating 1n parallel Each pump 1a

an 8 inch Pelton double suction centrifugal pump witb a

rating of l$00 gallons per minute at a head ot 75 teet with

a speed ot 1175 revolutions per minute Tbe inlet tlange

ot tne turbine is $pprox1mately 18 feet above the center

line of the pump

A direct current generator was coupled to the turbine

to receive tne power d veloped as shown in Figures 4 and 7 The generator is a Spr gue Electrodynamometer rated at SS horsepower with a speed range of 7$0 to l$00 revolut1one

per minute The classification is type LO 26A 2)0 volta

Figure 5 - View of Test Turbine

Figure 6 ~ View of Test Turbine

and 149 amperes lbe generator ti ld was aepar tely

excited using direct current from a motor g n r tor ampt

(l$ p 4~8)

The power output of the generator waa dissipated in

the water rheostat (3 p 488-489) shown in Figures 9 and

10 The galvanized tank contain d water ot variable d pth

on an electrode ot cast iron m aauring 1bull x 1 x 1

In the initial installation of the turbine it was

intended that the power output should be measured with a

Prony brak bull For th purpoa68 or this teat it was decided

that the brake was too instable and the generator was

substituted The platform for raising the generator the

nee asary two teet for alignment was built out of available

material In this case heavy laminated wood blocks reiashy

torced with other timbers were used and bolted through the

concrete deck (11 Pbull 36-$7)

Due to the light concrete deck the lack ot mas in

the platform and the slight misalignment in the flexible

coupling ao e vibration waa encountered It seemed to

ncr aae linearly to a maximum at the speed of bout 750

revolutions per minute Above this speed no vibPation was

noticeable The vibration waa not se~ere and does not

appear to have materially affected the test results

26

B Intrumentat1on ~ eaeur1ng Devices

The pressure head at inlet to the turbine vaa meaave4

bymeane ot two )6 inch waterbullmeroury manometerbull connected

in series as shown in Figure 8

The terminal voltage ot the generator vas meaeured by

a laboratory voltDleter with a range to )00 yolta and callbull

brated to within 15 Yolta

The armature current bull and hence the line current was

measured by a laboratory ammeter with a range to 150 amperea

and callbrated to w1 thin o 7S amperes

Tae rate ot tlow was established by weight and time

meaeurementa The weighing ank has a capacity ot 121 000

poundsJ the weight belng indicated by Toledo direct reading

scales Timing was done with a hand atop watch with clivibull

aion ot 02 second

he ~ater level in the tailrace was dete~1ned by a

hook gauge lhie was read to the nearest 001 toot

The turbine and generator speeds were eaaured by a

hand tachometer The technique of almost cont1nuoua readbull

ings of the speed gave an error ot no more than 5 revolubull

tiona per minute

c Operational Procedure

Atter the water level in the aump was checked to

insure an adequate auppl7 the puapa were primed and

27

Figure 7 - Test Generator and Plattorm

Figure middot8- Instrument Board and Field Rheostat

28

started After venting they were valved for operation 1n

parallel

The motor generator set was started to supply the

field current and the circuit breaker was closed Water

wa added to the water rheostat to the level shown in

Figure 10 ~ field current wae minimized by cutting in

all the f ield resistance in the field rheostat of Figure 8

The l2 inch gate valve shown in Figures 5 and 6 waa

slowly opened and the turbine and generator brought up to

speed The 12 inch gat valve and turbine were vented and

the pumps were checked to insure neither had lost ita prime

lhe water rheostat offers very steady load 1f the

water level is essentially constant and the water temperabull

ture 1a fixed () p 488~89) In order to maintain this

constant temperature it was decided not to circulate the

water in the rheostat but rather to allow the water to

boil thua achieving the desired result A standing wave

was set up on the face ot the electrode by the boiling

action but a atable load was eatablished except at very

low water leYels where th11 agitation led to fluctuationa

in the line current

After putting the turbine and generator on the line

maximum power was dissipated in the rheostat by redueing

the turbine speed to between oSO and Soo revolutions per

minute Salt vas added to the rheoetat wat r to increasemiddot

29

Figure 9 - View of Water Rheostat

Figure 10 - View of Water Rheostat

Separate Field ExcitationFrom Motor-Generator set Compound Water-Mercury

---shy

re Manometer

I Q)

~ 0

~

Book Gauge

Open Channel

I

Slap Reservoir

Figure 11 - Wat~r Flow Diagram and Electrical Layout

31

waiting pe~iod ot perhaps an h~ followed

while the boiling point or the water wbulls reacbe4 During

this ti+ne the manometer was vented end eheoked electrical

measur1ng 1nstlUments were connected end the hook gauge was

adjusted tor elevation

It required about two- houtte tor the generator to reach

its normal operating tempe-ratu~e_ After the water in the

rheostat and generator had reached their operating temperabull

turea it was possible to begin the taking of data

The only vaPiable which was controlled wee the turbineshy

generator speed However the upper l1ut1t of safe line

current was slightly over 100 ampJilPampPes and the eireuit

breaker would open when the current reached lOS ~ere bull

Control was exercised by means ot regulating the water

level and salt 1n the water rheo tat and the res1stsnoe of

the tield rheost t~

The etfeet ot each type ot regulation on the three

variables is shown below

Volta Aaperebull Speed

Inc Dec Inc Dee~ Inc Dec

Wa~e1 Level Inc Dec~ X

X X X X

X

Salt Concentration

Inc Dec X

X X X X

X

field Resistance

Inc Dec

X X

X X

X X

32

Jlot all methods gave the ame amount ot change in a

given variable and a period of experiment and trial led to

the following scheme starting the rune with the lowest

turbine speed the water level was high with a high amount

ot salt and the field resistance was cut completely out

Aa it became necessary to increase the speed tor each

aucceasive run either cutting in t he field resistance

decreasing the salt concentration or lowering the Vater

level would produce the desired result However decreasbull

1ng the salt concentration had to be done Without a net

gain in water which led to a tluahing procedure that was

not particularly good because cold water was introduced

which required time to heat to the boiling point Cutting

1n additional field resistance was a good method but th1a

increased the amperage possibly to the point of opening

the circuit breaker Lowering the water level was aatiashy

factol1 until the level got too low causing the current

fluctuation previously mentioned Actually it turned out

that a combination of lowering the water level and cutting

field resistance in would carry the speed from ita minimum

to 1ts maximum value it the proper choice were made each

time the speed waa to be changed At the conclusion of

each aet of runs at a high speed the water level would be

low and the field resistance high

33

TURBINE

PAD AND DECK

TAILRACE

WATER SURFACamp

CONCRETE

DRAFT TU1B INSERTS

7 5( DRAFr TUBE

FLltJI ARIA

5~ DRAFT TUBE

FLOI ARSA

Figure 12 - Sketch of Draft Tube and Test Inserts

34

Figure 13 - View of Draft Tube Insert

Figure 14 - View of Draft Tube Insert

D c __ ~s_middot hedu_le of

A number was assigned to each run The fi~st number

applies to the draft tube tlow areas

1 bull 100~ flow area or 0~ oonatriction

2 - 7S tlow area or 2$ conatr1ct1on

3 SoC flow area or so~ constriction

The second number refers to the wicket gate openings

9 over gate opening

6 bull intermediate gate opening

4 bull one h lt gate opening

The third number 14entif1ea the location of the particular

1Wl in a set ot rona made at a given dratt tube tlow area

and wicket gate opening

fnua run number 1bull4bull10 would identity this as the

tenth run ot a set made at halt gate with 75 ot the draft

tube t1ow area

Rune w re made tor a g1yen dratt tube condition

Firat tor tull 41-aft tube flow area seta ot rune were

made for the overgate halt gate and intermediate gate

conditione An insert was placed in t he draft tube and

rune based on the same gate conditions were made tor the

7S~ draft tube flow area case The insert was then changed

to allow only $~ draft tube flow area

The inserts are sketched 1n Figure 12 and photographed

ln Flgurea 13 and 14 They oonaisted of circula~ segments

36

or l2 ineh plywood mount 4 on wooden legs 10 inches high

The 1nse7te were placed in position and secured by th use

ot a-clamps on the legs and the outside ot the bottom of

the draft tube The obvious disadvantage to this method

waa the neoeasity tor draining the water from the tailrace

tor a change ot 1naert The advantage vas of course the

simplicity ot design and construction

Chapter V

DATA-A Original Data

The normal data-taking crew consisted or two men

Assuming adjustments having been made to secure a certain

turbine speed (aee section on Operational Procedure) one

man would take semi-continuous speed readings with the hand

tachometer until a state or rotational equilibrium was

reached This could be only a period or two minutes up to

ten or tifteen minutes As soon as steady speed was

assured the data taking would begin The second man went

to the weighing tank Where a minimum ot three weighingamp

were made The requirement was to get three consecutive

readings such that the ditterence between tbe smallest and

largest time did not exceed 04 seconds The time to

collect a given weight ot water was then assumed to be the

arithmetic average of the three times He then went to the

hook gauge determined the hook elevation and then

recorded the data on the data sheets The first man meanshy

while had taken readings of the line voltage line current

and manometers and checked the turbine speed by multiple

readings During the length of the run all values were

38

checked to determine mean values for recording

The minimum length of one run was about five minutes

If one or more measure ants tended to drift during the run

all values wer discarded and a new run began as soon aa

qu111br1um was stabl1shedo

B -0-al_e_u_l_a_t--d Data

The h d on the tu~bine 1 defined by

($)

The maxtmwm velocity V4 was equal to about o8 tampet per

secon4 which makes it a negligible quantity when converted

into velocity head

An engineerbulla level was used to deterine the d1ffePshy

ence 1n elevation between the compound water-mercury manoshy

meter and the hook gauge Using this value the equation

for turbine bead becomes

where z4 is the hook gauge reading

The rate of flow 1 cent

w weight or water collected average time to collect

The inlet velocity v1 vas calculated by dividing the

weight rate or flow by the specific weight of water and the

)9

area ot ~e inlet pipe This was equivalent to dividing

the weight rate of flow by 490 Then the power input to the turbine is equal to

WHpin rri

10 (6)

Also

(P ~ut) Turbine

(P out) + Generator

(P lost) Generator

The power output of the generator is simplJ the

produot ot the terminal voltage and the armature (line)

curPent The power lost in the generator can be subdivided

into copper losses and stray power losses lo evaluate

these cunes based on losses of an identical generator

11leampsured by the Department ot Mechanical Engineering were

used The loss curves are reppoduced in part in Figures

15 and 16

Determination ot generator losses proceeds as tollowau

(1) From Figure 15 detem1ne the vo1tage drop in the

armature circuit using the temperatures of 1220 F and the

meaaured current

(2) The induced voltage is t~e sum of the terminal

voltage and the voltage drop 1n the armature circuit

() Entering the induced voltage and the turbine speed

into Figure 16 the stray power loss can be determined

(4) The copper lose can be evaluated from Figure 1$

using the measured current and the temperatlll-e of 1220 P

40

25 ~------~--------~--------~------~

U) -U) - 20

f-4 ~

-~ -gt 0

0

VOLTAGE DROP

~ - i -

- bullbullbull bull - -middot-middot -+ ~- + -t--+ ~ - ~ middotbull ~-~ middott- -+----- _ -4 middotmiddot- --~-+-t---r~~ ~--+t-t- - ---t-c-++~-ulf--

0 50 75 100

Figure 15 - Curves of Generator Voltage Drop and Copper Loss

41

1200

1000

800

600

800

0

0

~-

middot--~ 1shy --1 + bull l

100

I -

150 200

IIDOOED VOLTAGB (VOLTS)

Figure 16 - Curves of Generator Stray Power Loss

_ j

-bullshy -L---- shy middot -shy

250

- r

42

(5) The generator los os equal the sum of the eopp r

loss and stray power loss

~e efficiency or the turbine is taken as

etticiency u e =P out (8)Pin

~ample pound Determ1n1gg turbine Power Output

The following data are taken trom that ot Run 1-9-1

Line voltage 1040 volts Line current 870 amperesSpeed 355 revolutions per minute

The induced voltage 1a determined as follows

Line voltage 1040

Voltage drop 90 using Figure 15 with line current of 870 amperes and temperature ot 122 degrees)

Induced Toltage 1130 volta

The power output of the turbine is determined as follows

Generator output 90$0 (line voltage z line current)

Oopper loss 7 (using Figure 15 with line current of 870 amperes and temperatUe or 122 degrees)

Stray power lose 470 (using Figure 16 with speed ot 355 revolutions per miDUte and induced voltage or 1130 volts)

Turbine power output 9527 vatta

or turbine power output 1s 12z2 horsepower

43

The conversion of the calculated data to a constant

head is based on the conventional assumption of constant

efficiency regardless of turbine head For a constant head

ot 81 teet a purely arbitrary figure the tollowing relashy

tionships are ass1lJiled to be true

I ____L (9) (i)l72

(10)

For these two values the specific a peed may be combull

putedt

N t Jt VPt (11)8 243

Chapter VI

~RESULTS

A -Pr_e_ae_n_t_a_t_t_o~n g Reaultbull

Graphical presentation ot the results ot this te1t

are given as follows

Figure 17 -Turbine characteristics with 100~ dratt

tuba 1low area

Figure 18 - Turbine characteristics with 7S dratt

tube tlow area

Figure 19 bull Comparison ot power and etticiency at

over gate conditions between 100 and

75~ draft tube flow area

Figure 20 bull COZQparison of power and ettic1ency at

halt gate conditions between 100~ and

7S~ draft tube flow area

Figure 21 bull Comparison of power and etticiency at

over gate condition between 100~ and

So dratt tube tlow area

Figure 22 - Comparison in variation ot apec1t1c

speed between 100 and 75~ dratt tube

tlow area

50

45

20

-bull - 1--shy40

bull J-~ 30

~ ex

~ 20

~~ ~ -)q

I

~ - _

- -

10~ OF DRAFT TUBE FL(Jif AREA

CONSTANT HEAD OF 8l FEST10

POIER OUTPUT EFFICIENCY SPECIFIC SPEED

0 ~--------------_--------~------~------~ 400 600 800 1000 1200 1400

TURBINE SPEED (RPM)

Figure 17 - Turbine Char~cteristics with 100 Draft Tube Flow Area

50

46

-bulllle

~ 7 ~ OF DRAFt TUBE FLOW AREA

0 -~~-rl C05STAMT BEAD OF 81 mET 1J~

POIER OOTPUT ---+- ---o ~_H EFFICIDCY ~ I shy

bull ql SPECIFIC SPEKD - ~ -

bull ~ J 10 L rmiddotr- r- -

bullz- I

~~ 30 ~~--~----~~-

20 ~ ~ middot-shy

26

~~ 25

~0 ~r-----i (

Tbull -bullshy

400 600 800 1000 1200 1400

TURBINE SPEED (R PK )

Figure 18 -Turbine Characteristics with 75 Draft Tube Flow Area

47

EFFICIENCY 60

1-----shy

-~ 50~--~--~~-~middot middot middot middot r~-~----~~~~---4~-r~-~~gtt

II

POWER~ J ~ bull bull

u I

sH

40~------+-------+---- -~~--~~-~~~~

~----~rl 1 bull

I

I

0~--------------~------_------~--------

~ -OVER GATE CONDITION

COIJSTANT HEAD OF 81 FEET

0 o 10~ DRAFt TUBE

_-- _ 7~ DRAFT TUBamp FLON AREA II

10_~-----+--------r-------r----~~

400 600 800 1000 1200 1400

TURBINE SPEED (RPM)

Figure 19 middot - Comparison between 75 and 100 Draft Tube Flow Areas of Power and Efficiency at Over Gate Conshydition

48

t

bull --4 r ~- ~ middot~

70 1-----------+-~~~~~+middot ~ ~~ middot middot -~~--~~--------~~----~-+1

-~-

Atbull bull

lla-

60

amp0

40

20

10

oampOO

t _ - - ~-+- - -~-

l2 GATB COJIDITIOJJ

COJISTABT HJW) OF 81 JBET

o 0 lOQ( DRAFl TUB8 FLOI AREA

e-- - e 75 DRAFT TUBE FLOW AREA

800 1000

- r-

~

TURBIbull SPBIID (RPII)

Figure 20 - Comparison between 75 and 100 Draft Tube Flow Areas of Power and Efficiency at Half Gate Conshydition

49

60

50

-40

bull 30

IIQbull

20

10

0

400

- t - ~

EFFICIENCY

_J bull - bull bull

~ r r middot t -+ shy L -t -

OVER GAD COliDITIOI

CONSTABT BEAD OF 8l FBB

o o 10~ DRAFt TUBE FLOI ADA middot--- 5~ DRAF TUBE FLQPi AREA

600 800 1000 1200

Figure 21 -Comparison between 50~ and 100~ Draft Tube Flow Areas of Power and Efficiency at Ove~ Gate Conshydition

50

25

20

15

10

0

Figure 22

~- T -4 -t- -l --~-

t-~ I

middot --~- t ~---- _ __ _ + --

----~- --r-- --

~-=J-~-=-~ -==~ _ ~- -- ---f---1 - shy

CONSTANT HEAD OF 81 FEBT

o--o 1~ DRAFT TUBE FLltll AREA

75C DRMT TUBK FLCIJ AREAmiddot--middot-middot 600 800 1000

TURBINE SPEED (RPK)

Comparison of Specific Speeds for 75 and 100 Draft Tube Flow Areas

51

B Discussion 2 Result

Consideration of Figures 17 and 18 indicates the

overall eftioi ncy pattern or hill is significantly or

rounded for the 7$~ flow area than for the 100~ flow area

bia implies a greateP efficiency is possible at speeds

leas than or greater than design speed with an insert in

the draft tube However the muilDum efficiency is lemiddotas

Direct comparison at over gate conditions is made in

Figure 19 ~e same general trend is noted tor both the

etticiency and power curves for the 7$~ flow area case

The eurves show higher values at overspeed than do the

correaponding cWvea for the 100 flow area case It ia

not clear whether the curves have been shifted by the dratt

tube constriction or whether the curves simply bulge past

the normal curves at both overspeed and underspeed condishy

tions The power curves apparently peak near the aeme

point bullalthough maximum power is still obtained with the

normal draft tube area

For the comparison at halt gate operation shown in

Figure 20 a general improvement has apparently been made

by restriction of the draft tube flow area At every speed

the etticienoy and the power is greater for the restricted

tlow case The two ett1o1ency curves and two power curvea

are practically parallel throughout the speed range ot

teat

As the flou aroa i e decreased still farther a s1gn1

ticant change appears Reterr1ng to Figllle 211 tor the $0

flow area curves it a obvious that exit losses have

become excessive at the overgate condition because the

efficiency and power are everywhere leas than tor the case

of normal draf t tube area

Earlier it was pointed out t hat 1t the r esult s 1nd1bull

eated an increase in both power and ef tieiency- t hen it

could be assumed tha t the additional los s i ntroduced with

the draft tube insert is less than the diminished losses

due to leas shock losa and water passage losses For the

places where both the efficiency and power have been

increased we can assume that the insert has improved turshy

bine performance

For the places where the power haa been decreased

nothing can be said as to the elimination of ampbock loss

because the new lose present with the drat tube insert has

overshadowed any gains in eftecti Ve head upatJ-eam of the

insert

Near the peak of the efficiency hill howeve~ it may

be pointed out t hat shock loaa ie a minimum with a normal

draft tube and the insert merely adds an additional loss

with the resultant decrease in maximum efficiency tor the

7$~ flow area case

Perhaps the most s1gn1ticant set of eurves is shown aa

53

Figure 22 In this graph values of specific speed tor the

75 and 100~ flow area cases for both over gate and one

halt gate openings are plotted against turbine speed At

every speed and both gate openings the value ot specific

speed for th 75~ flow area case is greater than that for

the 100 t1ow area ease

Since the head is a constant for both situations this

may be interpreted in either of two ways trom equation

(11)

(1) For the same turbine apeed restriction of the

draft tube t1ow area resulted in greater turbine power

(2) For the same power amputput the turbine with 75~

draft tube flow area operated at a greater speed than did

the one with 100 flow area

Since the required diameter of a turbine varies

inversely with the speed the second interpretation could

be stated such that a smaller turbine could be used to

develop the same power output

Whether viewed trom the aspect of increased power

greater speed or reduced size the performance of the turshy

bine with reduced draft tube flow area is superior to that

with the nolmal flow are in the draft tube

The curve of specmiddotific speed versus turbine speed for

the so draft tube flow area case at over gate cond1t1ona

was not included in Figure 22 This curve lies below that

for the 100~ flow area c se at all speeds

In elaboration ot the second interpretation of Figure

22 attention is directed to the relative magnitudes ot

increased apee1f1c speed tor the two gate openings Assumbull

ing that the increase in specific speed implies a shift ot

the power curve to the right along the turbine speed scale

the power curve would be shifted more tor tbe halt gate

opening than tor the over gate opening

It thia trend could be extrapolated to the other gate

openings the tendency can be seen tor the line ot beat

speed to rotate toward the line of the operating speed as

illustrated in FigtU-e ) The advantage of this has already

been discussed

This particular turbine has a low specific speed tor a

reaction turbine Aa the rated value of apecitic apeed tor

reaction turbines increases the line ot beat speed departs

even more radically from the line of operating bullpeed It a

test similar to this were conducted on a reaction turbine

ot gleater specific speed it is pJobable t hat the rotation

ot the line of beat apeed would become more p~onounced

The scheme used in th1a teat had two obvious dr wbull

backs The first was the decision to leave all the wicket

gamiddottes installed tor all conditions ot the draft tube

These gates predominated in control of the tlow The

inserts added to the draft tube merely acted as auxiliary

55

contrGla

The aecond drawback was the choice or device to place

in the draft tube The reasons foll selection of this type

of device have been previously mentioned It is to be

anticipated that adaptation ot dratt tube flow control

would result 1n a better device for an actual turbine

installation Such apparatus might take the form of a

pneumatic bladder or a h7drau11oally operated variable

venturi section in the draft tube It is conceivable that

the gate as used in this test might be adapted also

Chapter VII

OONCLtJSIOfS

From the results of this test the following eonolubull

e1ona aa to the effect ot a variable draft tube flow area

on the performance or a r action turbine may be drawn

(1) The effect ot a variable draft tube tlow area 1a

generally favorable upon the operat1Gn ot a reaction turbull

bine because or the tendency tor the line or beat speed to

rotate toward the line ot operation This resulte in

better performance of the turbine at partbullloads

(2) he etf1o1ency eh111 tor the turbine beeomaa JDore

tlat at the top leading to a smaller max1JilWD effic1enc7

but e reater etticieney at other pointe of operation with

the insertion ot an auxiliary control ror the rate ot tlov

in the draft tube

(3) The power output of the turbine will increase at

over speed over gate conditione as well a at part gate

conditions with the proper amount or draft tube eonatr1cbull

tion or flow

(4) It is possible to eliminate at least partially

eddy type shock loss by tho introduction ot flow control

in the draft tube

BIBLIOGRAPBl

1 Addison Herbert A treatise on applied h-draul1cs New York Wiley 1954 724 Pbull

2 Allen o M and I A Winter middot Co111parative testa on experimental draft tubes Tranaact1ons ot the American ociety ot Civil Engineers 87t893bull970 1924

3 Barrows a E Water power engineering 3d ed ew York McGraw-Bill 1943 791 Pbull

Bovet G A Modern trenda in hydraulic turbine design4middot in Europe Tranaactions of the American Society ot Mechanical Engineera 75975bull993 1953bull

s Oreager William P and Joel D Justin Hydroelectrichandbook 2d ed New York Wiley 19$0 1151 Pbull

6 Daily Jamea w Hydraulic machinery Int Hunter Rouses Engineering hydraulics Hew York Wiley 19$0 p 8$8bull99

Daughertybull Robert L Bydraulie turbines ew Yorkbull7middot MoGrav-Hlll 1920 281 Pbull

8 Daugherty Robert L Inveat1gat1on of tne performance ot a reaction turbine ~anaactiona or the American Society ot Civil Engineers 7811270bull1304 1915

9 Davie L M Model and prototype testa Int Trend in hydraulle turbine practice symposium lranaactions ot the American Society ot Civil Engineers 1o63S3middot368 1941

lfJ Doland James J Hydro power engineering Hew Yorkbull Ronald 1954 209 Pbull

11 Gandy Theodore s and Elmer c Schacht Direct curshyrent motor and generator troubles operation and repair New York McGraw-Bill 1911 293 Pbull

12 Gibaon Arnold H Hydraulics and ita applications5th ed London Constable 1952 813 Pbull

58

13 Button s P Component loases in Kaplan turbinebull and The prediction of efficiency from model tests Probull coedings of the Institution or Mechanical Engineers168743-762 1954

14 Knapp R T~ Oavit t1on mechanics and its relation to the d sign or hydraulic equip ent Proceedings or tne Institution ot Mechanical Engineers 166150bull16) 1952

15 Langsdorf Alexander s Principles of direct curHnt mach1nee 5th ed New York r~cGrawbullH1ll 1940 746 Pbull

16 Lsrner Chester w Characteristica of modern hydraubull lie turbines Trans e~ions of the ~~erican Society ot Civil Engineers 66306-386 1910

17 Linsley Ray K Jr and Jobulleph B Franzin1 Eleshyments of hydraulic enginebullring New York McGrawshyBill 19$5 $82 Pbull

18 Mead Daniel w Hydraulic machinery llev York McGraw-Hill 1933 396 Pbull

19 ead Daniel w Water power engineering New York McGrawbullRill 191S 843 Pbull

20 Mockmore Charles A Part gate operation at water turbines Corvallis Oregon State College Department ot Civil Engineering 1933 11 numb leaves (Unpubshylshed typescript)

21 Mockmore Oharles A Flow characteristics in elbow dratt tubes Transactions of the Amez-ican Society ot Civil Engineers 103402middot464bull 1938

22 Moody L F Hydraulic machinery In c v Davis Handbook ot applied hydraulics New York McGrawshyHlll 1942 1082 Pbull

2) Ptau At-nold Hydrbullulie turbine handbook ld ed Milwaukee AllisbullOhalmers ManufactUIing Company 1948 70 Pbull

RheingalUI w J Recent developments in Francis turshybines Mechanical Engineering 74189-196 1952

25 Russell George E Hydraulica 5th ed New York Henry Holt 1942 466 Pbull

26 Safford A and E P- Hamilton American mixed tlow turbine and ita setting Tranampactions or the Amerieal Society of Civil Engineers 851237bull1)56 1922

27 bull Spannhake W1lhe1Dh Problems or modern pump and tur b1ne design Transactions of the American Society of Mechanical Engineers 56e22$-248 1934bull

28 Sutherlandraquo R A Better ethod or representing and middot tudying water turbine performance ~ansaetions ot thmiddote American Society of Mechanical Engineers 68t675bull 686 1946

29 Teats ot five models or draft tubes tor turbines Engineering News-Record Pbull 182-184 Aug 2 1923

30 White w M American hydztaulic turbines Mechanical Engineering S2t390bull39S 1930bull

31 White w M lhe hydraucGne rega1ner1 its developmentand appl1eat1ons 1n hydroelectric plants Meohanlobulll Engineering 43t37Sbull380 1921 middot

32 Winter I A Economic principlebull in designbull Int Trend in hydraulic urbin practice bull a ampoeiumTranaaot1ona ot the American Society ot Civil Engineerslo6332bull3S2 1941

33 Wiel1cenua G F Fluid mechan1ca or turbo-machineryNev York McGraw-Hill 1947 613 Pbull

APPENDICES

c

Appendix A

NOATIOB

A Angle between the absolute velocity vector and the tangent to the rwmer Subscripts 1 and 2 refel to entrance and exit ot the runner blade

B Angle between the relative 1elooity vector and the tangent to the rwmer Subscripta 1 and 2 refer to entrance and ezit or the runner blade

Angle between the tangent to the runner blade tip and the tangent to the runnel- Subscripts 1 and 2 reter to entrance and exit of the rt1rmer bladebull

Blade angle-gate opening conetant defined by equation (1)

e 09erall efficiency

g Gravitational acceleration assumed constant at 322 teet per second per second bull

H Turbine head detined by equation ($)

m Exit loss coeft1e1ent

Turbine speed expressed in revolutions per minute

Turbine speed under a constant head of 81 teet

specitic apeed of the turbine under a constant head ot 81 teet

p Power output in horsepower ot the tvbine

Power output of the turbine Ulder a constant head ot Sl teet

Pl- Pressure head at entrance to the tUlb1new

l1 Peripheral velocity ot the runneP Subacr1pta 1 and 2 refer to entrance and exit ot the JUnllampr blade

62

v Relative velocity reaulting trom the combination ot the absolute water velocity V and the runner periphshyeral velocity u Subscripts 1 and 2 refer to entrance and exit ot the runner blade

v] Relative velocity vector necessary to produce a tanbull gential entry into the runner blades

V Absolute water velocity Subscripts l and 2 refer to entrano and exit ot the runner blade

v2 Velocity head Subscripts 1 and 4 reter to the ~8 entrance to the turbine and the tail~ace wate~

w Unit weight ot water assumed constant at 624 pounda per cubic toot

V Weight rate ot flow in pounds per aeooncl

XX Velocity component ot ahook See Figule 2

Z Elevation head Subscripts 1 and 4 reter to entrance to the turbine and the taibace water surfacebull

Appendix B ORIGINAL DATA-Run

lfwnber

0-4-1 0-4-2 0-4-3 o-4-4 o-4-S o-4-6 0-4-7 0-4-8 0-4-9o-4-lo o-4-11 o-4-12 0-4-13

o-6-1 o-6-2 06-3 o-6-4o-6middotS o-6-6 o-6-7 o-6-8 0-6-9 o--6-lo o-6-11

Speed

rmiddot2middotbullmiddot(1)

336 38$ 451 S$9 620 669 6lt)$ 120 787 860 932

102imiddot109 bull

352 355 443middot 543middot 620 654AJs32

911 1001 1111

~essure Head rt (2)

410 410 416 426 431 43-7 439 44-9 452 467 482 soo $1 bull $

350 351 35middot7 )66 37-9 37-9 392 41 bull 3 43middot3 460 489

Elevation Bead

fjj $7 $7 $7 $7 $7 $7 51 57 5-15858 $8 58 56 56 $6565656 51 575As5a

Velocit Head

flj 07 07 07 06 06 06 06 os 05 os0404 03

09 09 oa o8 o8 os 07 07 06 o~o

Total Head rt ($)

47middot4 4A44 o 489 49-4 soo $02 $11 $14 $29 5imiddot45 2 576

41 bull $ 416 421 430 44middot3 44middot3 456 47-7 496 523551

Plow

lbtjec

326 324middot317 311 306 30029middot28 middotmiddot middot 386 275middot260 240 218

359 36~35 bull 349 345middot 339 330 318 300 273 240

Line Potential

vyqjbull 1060 1220 ~-0o 1920 2150 2000 2$60 2000 1940 18)015io11 o

1000 1100 139bull5 1760 1925 16$0 1620 1610 1540 1330 870

Line Current

amlscs 960 900 830 740 730655 70bull 0 530 660 600 5imiddot54 6 )60

982 930 860 780 ~3-545

79-5 74-5 670 560 370

P

Appendix B ORIGINAL DATA (Continued)

Run Number

Speed

Pbulltmiddotbullmiddot )

leasure Head ft(2

Elevation Head tt(J)

Velocity He-dfmiddotj

Total Bead tt($

Flow

lbstsec( )

Line Potential vo~ta( )

Line Current

amjs (sect

0bulllt)-1 0-9-2

3ll6 398

28o ~~1

$6 56

1o 10

346 347

390 365

1ooo 1190

aao 835

0-9-3 0-9-4 o-9-S

472 565 632

292 305 312

$6 s6 56

10 o9 o9

)$8 J7~o 37~7

381376 37o

1)6614oo 141o

820 ass ass o-9-6 0-9-7 0-9-8 o-9-9 0middot9-10

680 120 762 844 920

)24337346 366 390

56 $6 56 57 $7

09 os o8 oa 07

)89401 410 431454

367~ 357348 34o 322

1400 1J6o l36o 1310 1170

843 820 7957So 67~0

0-9-ll 0-912

1001 1100

41 bull 7 45-3

s 7 6~0

06 os 480 $18

299 268

980 65$

560 36~5

1-4-1 1-4-21-4-l1-4shy1-4-5 1-4-6 l-4-7 1 4-8 1-4-9 1-4-10 1middot4-ll 1-4bull12

354middot452 562 62q 674shy102 752 760- 863 932

1022 1100-

)82389 4014oa 416 41--7 423 428 44-2 45-7 486 49-2

51S757 51 5-7 5middot15zs sa $8 58 59

07 07 06 06 06 06 06 os o bull o 04 o J

446 45-)46middot4 471 ti7-9480 q86 491505 $19 548 55-4

)28 320 311 306 300 295 291 286 269 2582iimiddot21 bull

1080 14Lo 1550 153-5 1470 141-0 1385 1310 1310 1230 1120 855

970855 875 91-0 94~0 975 966 995 860 77-S 610 4fo

0 ~

Appendix B ORIGINAL DATA (Contirmed)-Run Speed Pressure Elevation Velocity Total Flow Line Line

Number Head Head Head had Potential Current rtjjmbull t~ bttec vyfs am~a12) ( ) ti fli 8

1-6-l $6 33$ $6 0bull9 400 364 1100 93 0 1-6-2 41 34laquo2 $6 oa 406 JS7middot iios a5s l-6-3 500 3~0 5bull6 os 356 1 1 o aos 41middot~1-6~4 35bull4 5-6 oa 41middot 352 16~0 82 0 5~1-6-5 5 bull 36_2 Sbull6 08 42bull6 349middot 161 ~ 0 86~0 1-6-6 622 366 $6 oe 43bull0 345middot 158 0 88~$ 16-A 649bull 37bull1 56 os 43-S 342middot 1570 895 1~- 386 57 07 46-0 192 ) 125A44 333middot 1-6-9 3) 404 5middot1 07 468 317 1620 675 1610 911 42-4 5-7 o6 48-7 298 168 0 61 0 1-6-11 999 451 56 os Sl ll 276 ~2-0 530 1-612 1115 485 58 04 54middot7 238 90 )3 0

1middot9-l 355 279 56 10 )45 385 1040 870 1-9-2 399 28J $6 10 )49 38$ 1140 86 5 l-9-3 ~ ao 291 56 ~0 35middot1 J8J_ JJ6o 815 1bull9-4 579 303 56 09 )68 375middot J4JO 830 l-9bullS 40- 313 )6 09 31middot8 370- 1460 82~0 1-9bull6 679 2) 56 09 3 bull8 364middot 1670 710 l-9-7 682 319 56 o9 384 ) 62 1460 79 5 l-9-8 724 33middot5 56 o8 399 3$6 bull 1480 76 -5 1-9-9 762 34middot3 $6 0 bull 8 407 )48 14910 13middotS 1-9-10 833middot )60 5middot7 os 42$ 339 144$ 686 1-9-ll 926 39middot1 5-7 07 455 318 1290 600 1-9-12 1000 41middot3 0-6 476 298 1115 510$ ~ 1middot9-13 1105 452 s o4 $14 2$6 710 )10

~

Appendix Bt ORIGDIAL J (Continued)

Run Speed Pressure Elevation Velocity Total Plow Line Line Number Head ltead Head jlamp$d P()ten~ibulll Current

r~~~m ft ft lbs~seo voltattj rgj twimiddot t 1 t2gt lt3 ou t ( rt

2-9-1 384 289 S 6 10 35 5 1400 1170 810 2-9-2 443middot 29$ $6 ltimiddot9 360 379middot 11(0 87$ 2-9-J 536 30bull 3 sc 09 )68 374middot 1)40 84 bull) 2-9-4 571 306 $6 09 3~1 372 120bull 0 955 2-9-5 623 316 S6 09 J l )6S UJSo 77$ 2bull9-6 669 327 S6 09 )92 )61 1240 905 2-9bull7 712 )39 56 os 40-3 351 12(0 86 bull0 2-9-8 ~5$~ J48 56 oa 412 348 1290 81 bull ) 2-9-9 04 )63 56 oa 42-7 339 12ltJO 76$ 2middotmiddot9-10 8$2 376 5middot1 07 440 33~- ~ o 710 2-9-11 955 394 5-1 o6 457 300 1100 506 2middot9-12 1000 421 $7 06 48middoti 295 1020 $18 2-9bull13 110~ 463 56 05 $2 267 620 3~0

oshy0

Appendix Gt CALCULATED DAgA

Turbine Run Generator Generator Turbine Turbine Efficiency Turbine Turbine Specit1c

Number OutputKWlt21

Loa~Jes KWlol

Outut K bull (H)

Input RP 12)

middot Percentlt13gt

Speed r~Jmiddot(

0ltput HP ~1

Speed r-m

( 6) middot

o-4-1 0middot4-2 0-4-3 0-4-4 0-4-5 0-4-6 O-qmiddot7o-4-8o-4-9 0-4bull10 0-4-11 o-4-12

1018 1o9a 1220 1)62J40214oa1J4oo 1357 1320 1164 997 718

046 o59 071 092 096 1071oo 134 104 100 109 107

14261sso 17)01948 2008 20322011 1999 19 09 1708 14-84 11o6

281279 27-7 276 215 273271 268 268 26h 258 24-5

soa 555 62$ 705 7)1145 742 74-6714645 51s 45-1

440 sos 585 720 195 sso sao 9$$ 985

1065 1135middot 1230

318 357 319 416 422 419412 39middot9 378 324 260 191

102 12bull4 148 191 21bull 3 22o 233 249 24924middot9 238 221

0-4middot13 418 104 699 228 306 1300 117 18)

o-6-1 982 045 1376 271 $08 496 376 124 o-6-2 o-6-3 G-6-4o-6-5 0-6-6

1023 1200 13 73 J415 139h

051 0middot66 oaa ()bull 96 088

14-39 1696 1958 2026 1986

276 27middot4 273 278 274

$20 61 8 717 7)0726

q95615745 8)5685

390 ll5middot3 sos soo 490

127 170 218 243 2$$

o-6-7 o-6-8 o-6-9o-6-lo

1288 1199 1032 7-45

o9o 094 09$ 096

1846 1733 1511 1128

274 276 271 260

67S 629559 43middot4

980 1085 1165 1245shy

436 )83316 21bull 7

266 276 270 239

0-6-11 322 1oo 566 2141 2JS 1350 101 177 0 --4

Appendix C CALCULATED DAlA ( Continued)-Run

Number Generator Generator

Out2ut Losaes xw LW- 12gt (lO)

Turbine Out2ut

ltPlJ

Turbine Inat lfP Jig)

Etpound1e1ency

PireentDl

Turbine Sed x-~m( 1

Turbine OutEut RPJl)

Turbine Specific

SeeedrIbullntbull

( 6)

o-9middot1 0-9-2 0-9-3 o-lt)-4 09-$ 0bull9-6 0-9-7 0-9-8 0-9-9 0-9-10 o-9-11 0-9-12

aao 994

111$ 1197 1206 1180 11)21081 982 784 5-49 2)9

0middot45oss o6$ 070 07$ 0-77 (l77 or~ o s06o 8 096

123~ 1402 1$80 1698 17bulllS 168$ 16bull18 ~middot5430 1151 a~J4 9

24middotgt24middot3248 25~25 260 260 259 267 266 26middot1 2S2

sos 577 63-7 671 676 650 621 60036J4

327 178

$) 610AlO 3$

92S 980

102$ 1070 1157middot 1230 1300 137Smiddot

44middot4 soo 523 ssomiddot 540so6 46-5 432 368 274 18~8

J46 176 21-1 255 2802s_A 28 289 288 265 231 168

1-4-1 1-4middot2 1-4-3 1-4-4 1-4-5 1-4-6 1-4-7 1-J-8 1-4~9 1-4-10 1-4-11 1-4-12

10bull48 1231 13-S6 1397 1)821375 1))8 1303 1127 953 683) 51

048 067 o7A07 0 bull79 oa1 oss o bullao osa 0lt)0 096 099

J468 1740 1921 1978 1958 19$1 1911 lSSi162 1)98 1045

603

266 264 262 262 261 2512$7 2$6 24middot7 24-3 233 217

551 660 13middot3155 75-6 7~-97 middot4 72$ 67 51middotJ 44middot9 21middot1

475 605 A4220

875middot 910 970_

1000 1090bull 1166 1243 1330

5816

44middot444middot5 430 427 412 392 329 273 188 l0-7

117 101 204 22$ 2)7245 2562sa 257251 222 179

a-C))

Appendix Ct CALCULATED -DATA ( Ocntinued)

1-6middot1 1023 o$2 14-41 26S 505 41~6 26~

54middot5 13middot3l-6-2 1201 067 1boo 625 47-9 17shy~middot41-6bull3 1296 oA9 1 middot43 26 9 700 so5 20bull 4 l-6-4 l3j5 o 0 19~09 268 71bull3 A5o 514 222 1-6-5 1) 5 o81 19(gt4 271 725 51-5 238 l-66 1398 081 198) 27-0 736 8 S13 252~-middot l-6j 1405 083 199i 211 733 885 $middot06 2$9 l-6 13middot9~ 103 2amp 0 279 71 8 985~ 467 ~-69 1228 1 bull 02 17-SS 270 661 109$ 407 ~3~ l-6bull10 1025 100 lSll 26i 573 1175middot 27~S32middot~l-ampu 153 1-00 llft3 26 444 1270 22 24bull8 1bull6-12 294 100 52a 231 22 3 1360 95 172

1-9bull1 904 048 1275 2J4Z $28 S4$ 459 1$2 1-92 98$ oss 13-92 24middot4 57-0 6JO 49bull1 176 1-9middot3 1110 066 1$76 24middot9 63middot4 I2o 536 21-7 l--9-4 1187 072 1685 251 66$ 5 $$ bull 0 261 1middot9-5 llltJ7 1710 25middot4 67-3 93$ 536 28~20-671middot9-6 1186 o 8 1708 25-7 67) 980 $15 2691-9- 1161 oBo 1660 2$middot3 6$6 990 508 29-1 l~- ll-32 oB) 16sect0 2$8 632 1030 471 291 1-9bull9 109$ oa5 2$7 614 1075 29S~middot 0 4imiddot41-9-10 9~91 oas 262 S$1 1150~ 3 o 292 1-9-11 o9o u57 12JiO 21gt 26-77middot74

-45 26sect ~middot91-912 $69 091 sas 25 middot3 1)0$ 196 2J-8 1-9-1) 220 098 426 2)9 178 1390middot 84 16 6

0 0

Appendx C CALCULATED DATA (Continued)

Turbine Run Generator Generator lurbine Turbine Eft1e1eney Turbine lurbine Spee1f1c

Number Output Losses Outit Input Speed Output SPed middot k_-V KW R _ H_bull_P Percent r Thm HP rpm_ (9) tlo) 11) middot (12 _) (lJI ( ) (1$ (14)

2-9-1 9--46 055 1)62 258 528 580 164 2-9-2 1024 056 248 58 4 665 4 9 191iimiddot48 4~middot0 2-9-3 1132 067 05 2$0 641 795 52q 237 2-9-4 1148 065 1027 2$1 -~8 845 525 252 2-9-5 11 77 oso 16-83 253 6 910~ 522 270 2-9 6 1122 071 1600 251 622 960 47-5 2722-9-A 1092 015 1562 257 608 1010 445 2z12bull9- 1052 079 1514 261 580 1060 41middot7 2 2 2middot9-9 986 o82 ]429 26) 542 1105 372 277 2-9-10 915 086 1340 268 500 1160 334 27-6 2-9-11 638 087 972 254 )81 1270~ 229 250 2-9-12 )28 090 828 259 )19 1295 179 226 2-9-13 192 094 383 2$ 6 150 1370 7 3 152

-3 0

Page 13: The Effect of A Variable Draft Tube Flow Area on the

6

located above the tail race water surface without the

sacrifice of head However cavitation will cause pitting

of the turbine if the difference in elevation is too great

A common maximum elevation difference is 19 feet although

this figure is quite subject to modification between difshy

ferent installations (3 p middot 264-266)

There are many different types or draft tubes in use

today the choice or type being largely a matter or

economics (2$ p 368-370) A very common type particushy

larly among the smaller units is vertical with flaring

sides However the angle of flare is limited by the possishy

bility of separation of the flow from the sides In order

to achieve a certain discharge area the length of the tube

may be such as to require a great deal of excavation In

oases or this sort the cost of this excavation must be

balanced against a more elaborate design that does not

require as much excavation Other draft tubes in use

include the elbow hydracone and spreader types

Despite the differences found in construction and

design the draft tube must accomplish the desired objecshy

tives while offering a good hydraulic geometry to the flow

passing through it An inefficient draft tube defeats its

own purpose

Ohapter II

DISCUSSION ~ TURBINE LOSSES

A General

lhe head that 1a actually utilized by the turbine 1a

less than the effective bead as defined by equation ($) by

the amount that 1a lost due to mechanical and hydraulic

reasons

Mechanical loaaea are a function or the turbine 8p$ed

fhis ia not a lineaz- function but varies eomewhere between

N and N2 (3- Pbull 224)

Hydraulic losses encounteled in turbines ma- be subshy

divided aa to the location or occurrence (3 p 225-227) aa

fOllOW$S

(1) Penstock and scroll case

(2) Wicket gates

(3) Between wicket gates and turbine runner

(4) Runner passages

(5) Runner exit into draft tube

(6) Draft tube and

(7) At exit from the draft tube

The flow in the penstock scroll case wicket gates

runner passages and draft tube may be envisioned as

examples of flew in conventional pipes elbows and convergbull

1ng passages If this comparison may be made it could be

assumed that the losses encountered in these locations

would be proportional to vn ~ value ot N is normally2g

aesU111ed to be 2

he losses encountered between the wicket gates an4

the turbine runner and exit lossos are special cases which

will be discussed separately

B Shock toes_

The flow betwe n the wicket gat outlet and the runner

blade entrance is or particular 1nt rest because no direct

comparison vith common flow situations is obvious

Conaider the vector diagram (7 Pbull 7576) in Figure 2

The veetoo v1 is the absolute entering velocity of the

water and is fixed in magnitude and direction by the setbull

ting or the wicket gates The vector l11 1e the peripheztal

velocity of the runnel which tol any given turbine 1e

dependent only upon the turbine rotational speed The

combination of these two vectors ylelda the third vector

v1 which is the relative entering velocity ot the water

nere is only one setting ot the wicket gates for a

given turbine a peed that will produce an angle B1 which

coincides with the blade angle B1bull At other gate settings

the vector v1 will rotate and change in magnitude in such a

9

t ehion that B1 will beoome either greater or 1 sa than B1bull Th1 give rise to tbe phenomenon term d shock loasft

If B1 1a greater than B1 the relative ent ring veloebull

ityt v1 will have a compon~nt opposing the forward motion

of the runner The shock loss could be typified bullbull that

occasioned by direct impact or the water 0n the blade- If

E1 is lese than a] the vector l will overshoot the blade

and the flow will tend to eddy around the forward portion

or the blade tip

The shock loss can then be either due to impact or

eddying flow Since the area norm 1 to the radius at outlampt

of the w1eket gftee is essentially equ 1 to the area normnl

to the rad1u~ at the inlet to the turbine runner the combull

ponents ot vl and vl perpendicular to ul will b approxishy

mately equal This leads to the conclusion that xxbull ~epresenting the shock vector 1 parallel to Ulbull

For either the impact or eddy case the trigonometric

law of $1nee leads tot

XX

bull ul - sin (Bi-Al) vl eln Bi

It it 1a assumed that the energy lost in the shock 1a

the Telocity head ot the shock component XX then

10

VELOCITY VECTOR DIAGIWI

TYPES OF SHOCK LOSS

xbull X

IMPACT BDDJ

XX 1a Teloc1t7 caponent ot shock

Figure 2 - ~bine Runner Vector Diagram$ and Shock Loss Diagrams

11

2 shock loss (XX gt2g

C =sin (BimiddotAl)Let (1)sin Bi

(UlmiddotCV1)2Then shock loabull (2)- 2g

For a given gate opening C ia a constant ranging

from about 14 to 10 For a well designed wheel it is to middot

be expected that C would be approximately equal to U1V1

at rated conditions ie at point of maximum efficiency

This point will occur in the neighborhood of 3~ to 78

gate opening for moat turbines For overgate conditions

the angle A1 becomes larger so the value of C would

decrease For gate openings below rated conditions t he

angle A1 decreases and C would decrease One could expect

a fairly uniform decrease in t he value of C as the gate is

closed from t he overgate position

The velocity v1 is approximately constant for any

turbine speed since the area and rate of flow both decrease

fairly uniformly However for a given gate opening the

velocity V1 will decrease with increased turbine speed

From the foregoing comments and equation (2) the

following trends can be established

(1) For constant turbine speed the shook loss curve

will be close to parabolic in shape concave upward and

have its maximum near t he point of complete gate closure

--

12

and its minimum near the rated gate position

(2) For conatant gate opening the shook loss curve

will approximate a symmetrical parabola with its vertex

the point of minimum loas located at the rated condition

of operation (7 Pbull 79)

c Exit Loas

It can be seen from Figure 2 that the exit loss from

the turbine would be v222g if no draft tube were present

The addition of a draft tube permits the gradual reduction

of velocity by an increase in cross sectional area between

the exit of the runner and the exit from the draft tube

The exit loss and the frictional loss encountered in

the draft tube may be placed together in the expression

m va2 (3)Exit Loss ~---2g

For the ideal case of no friction in the draft tube

m is equal to the square of the ratio of the area at exit

from the runner to the area at exit from the draft tube

In an actual turbine installation however friction

will change the value of m (7 p 84-85) to somewhere

between that for the ideal case and a maximum ot 10

In the interest of maintaining a minimum exit loss

the turbine should be designed and operated so the velocity

V2 will be minimum This will occur when the discharge

13

vector is at right angles to the tangent to the runnerbull

ie the angle A2 1e ninety degree bull It ia to be expected

that this condition will be tultilled near the design con~

d1t1ons ot the ~bine

Current design praetiee 1 to have a small component

ot v2 in th$ direction of turbine rotation at rated condibull

tion$ ltS p 938)

For a constant turbine speed the d1seharg or exit

loss is ess nti lly a constant

For a constant gate opening the exit lo s curve is

aptrroximately a symmetrical pa~abola with ita vert x the

point or minimum loss located at a slightly lowe~ speed

th n the turbine rated speed (7 Pbull 79)

Chapter III

PROPOSAL OP ALlERMAlE MFTBO 0 CO TROL-A lz ~ Location 2 Control

Thua tar only practice and theoretical aspects appemiddotrbull

taining to present day turbinea have been d1acuaaed It

haa been presented that control over the ~bine ia ezerbull

oiaed b y manipulation of the wicket gatea located 11101led1bull

ately preceding the runner These gate - upon rotation

modify both the magn1tu4e and the direction ot the entering

velocit7 Moreover it has be n shown that a simultaneous

change in these two variables leads to inefficient operabull

tion by the introduction of shock loss he farther the

point of operation a from the rated conditione the more

aerioua ia the ahock loss encountered

Any attempt to better turbine pertorance at other

than rated conditione and tbne flatten the top ot the

etticieney hill8 must concentrate upon the lessening ot

the ahock loaa It 1a a aumed that 1 provement in the

scroll case gates and runners would lequ1re sueh pertecbull

tion 1n machine work and metal$ as to be prohibitively

expensive

It ie surmised that any move to elblinate eYen parbull

tially the shock loss would require separate control ovel

l$

the flow and gate exit angle Since it is improbable that

d1~ect1on could be controlled at any location other than

where the gatea are situated in current turbines it will

be assumed that guide vanes will be necessary regardlesa or the method used to control the rate of flow

The primary purpose ot th se guide vanes 1s that or control over the direction ot the incoming water They

should be free to rotate in much the same manner as ordibull

nary wicket gates in order to exercise control over th

turbine speed

If the rate ot tlov is to be controlled elsewhere it

must be modified either in the penstock or the draft tube

Devices that could be used are standard valves gates

variable orifices variable venturi sections and associated

flow regulating schemes

Alauming it were decided to locate such a device upbull

stream of the turbine it would be necessary to allow disbull

tance tor the flow picture to become reestablished prior to

entry to the turbine A contused flow making transit of

the turbine passages would only contribute additional loesbull

ea Such a distance allowance would be perbapa 20 to So

diameters (2$ Pbull 119-123) In large penstocka th1a would

repreaent a considerable distance Which from the viewbull

points ot convenience and control would be undesirable

Attempts to ascertain the effect or additional tlov

16

reduc ion at the wicket gatctsmiddot wae ade 1n the lfadraulioe middot

Laboratory of Oregon St middot te College in 1933 (20) Three

d1tterent thode ot reducins the tlow were t~ied

(l) Locking in the cloeed position pairs or wicket

gatea located opposite to eaeh o~er on the -periphery ot

the wheel

(2) Locking adjacent gates in an open position by

inserting blocks of wood between them and

()) Suocess1vely looking adjacent gates in the closed

position

The results indicated a arked reduction in both power

and efficiency when compared to the curves tor normal gate

operation However it was demonstrated that it was poae1bull

ble to ahitt the power and tfieiency curve ill relation to

turbine apeed lbis important feature will be diacussed

later

ihe main conclusion of the investigation was that conbull

trol by the conyent1onal wick t gates was auper1or to other

methode egtt control exercised at the gates the aelvebullbull

It would app$ar that the bebullt location tor flow conshy

trol would be in the draft tube since none of the objecbull

tiona prev1ously mentioned wou~d eziat there

As bas been stated previously the sole object or the

17

18

turbine is to produce power as etfic1ently as possible

The equation tor the power output of a turbine () Pbull 227)

PaWHe HP (4)55o bull bull Assuming the head 1a constant and a g te located in

the draft tube decreases bhe rate ot flow the power eu

only be increased if the etticiency increases

The ettective head Gn the turbine 1s conventionally

d r1ned as the difference between the auma ot the elevashy

tion head pressure head and velocity head at the entrance

to the turbine casing and the tailrace ($ Pbull 872)

lt ie recognized that the theoretical treatment ot

shock loss as given is highly approximate and serves only

to dictate certain trenda For example the area at xit

rom the wicket g tea CfUl be measuPed with some exactness

but there exists no guarantee that the wateP particles will

complet-ely fill the apace oz- will exit at the establiahed

g te angle The same can be said of the exit trom the

runner blades AssUIlptiona were implied which would indishy

cate that all water particles passing a given croea section

ampH traveling at the same velocity in the same direction

the e alone are autt1c1ent to show 11m1tationa in a theoretbull

1eal approach to the problem

Assume a turbine with ordinary wicket gates tor oonbull

trol compared gainst the same turbine with a gate in the

18

draft tttbe tor supplampment1ng control or the rate ot rlow

Let it also be assumed that the two turbines are opershy

ating at the same point It 1s desirable to predict relabull

tive performance of the two turbines 1 this point of

operation is such that edd7 s hook loss ot reasonable proshy

portions is present in the fir t turbine

~ tull erteot of the shock loss will be exper1 need

by- the fir t turbine

lhe second turbine will derive certain advantages 11

the gate in the draft tube is adjusted to reduce the tlov

1n the proper amount Since they vary a the square ot

the veloo1t7bull the lossabull in the aeroll case wiomiddotket gate

and runner passages will decx-ease aetet-r1ng to Figure 2 1

it can be seen that a decreased velocity v1 w-ill reduce the

eddy shock losa

The ent loss in the dJtaft tube of the second turbine

will be the sum ot the tr1ct1onal loss and the velocity

head at ex1t The velocity head dissipated will be greater

due to the closing action or the gate but the reduoed

t~ictional loss which ia a tunction ot the rate of tlow1

will partially balance this

It 1a entirely possible that the net reduction in

losses in the second turbine will lead to a greater ettibull

oiency and more power output than 4eYeloped by the first

turbine

19

In Figure 3 the plot ot power output against turbine

speed for Curv A~ represents the typical family of curvea

tor a reaction turbine Th b st sp ed is the locus ot

points connecting maximum eft1oiency at each gate opening

The operating speed is the coZUJtant turbine apeed which

passes through the point ot maximum efC1ciencr of the turbull

bine The plot of turbine efficiency against power output

for Curve A is also ahown

It the turbine with flow regulation in the dratt tube

oan demonstrate superior power and efficiency at part loads

the effect would be the same as a shifting or the power

curves toward the condition shown fop Curve B 11 Thisbull

illustrates th ultimate case of the uperpoait1on of best

and operating speeds It will be noted that the pet-form~

of the turbine ot Ourve Bu 1a better than that of CUrve

A at part loads because of ita ability to sustain a relabull

tively high etticienoy ovel a Wider range of power output

o Reguireaegts tort Test Velitication

It is desired to deterra1ne the effect on the turbine

performance b) the addition of a gate in the dratt tube

Th step in the teit will bet

(1 To determine the power output and efficiency ot

the turbine tor wicket gate settings above and below rated

conditione for a wide range ot speed

20

CURVEAbull

TURBINE SPSBD TURBID SPEKD

POIBR OOTPOl

Figure 3 - Turbine Performance Curves

21

22

(2 peat (l) with the gate installed in the drat

tube

(3) middot Converting middot all data to a constant head compare the

powere and effioiencies at the same wicket gate setting and

turbin speed tor the two cbullses

If the ddition or the gate indicates an improvement

in power output and efficiency and the powe~ curve shifts

to the right along the turbine apeed scale the advantage

ot draft tube con~ol of the flow will hav been demonshy

strated

Chapter IV

A E9J11pment

ih turbine used in this test is lJ 5 1nch Pelton

reaction turbine with a rated output ot 30 horsepower under

a head of 56 feet at a speed ot 720 reYolutiona per minute

Views of this turbine are hovn in Figures S and 6 The

turbine is installed on a concrete pad located over an open

channel in the Hydraulics Laboratory at Oregon State Colshy

lege The date of manufacture of this turbine was 1915

The water was delivered to the turbine from a sump

reservoir by two pumps operating 1n parallel Each pump 1a

an 8 inch Pelton double suction centrifugal pump witb a

rating of l$00 gallons per minute at a head ot 75 teet with

a speed ot 1175 revolutions per minute Tbe inlet tlange

ot tne turbine is $pprox1mately 18 feet above the center

line of the pump

A direct current generator was coupled to the turbine

to receive tne power d veloped as shown in Figures 4 and 7 The generator is a Spr gue Electrodynamometer rated at SS horsepower with a speed range of 7$0 to l$00 revolut1one

per minute The classification is type LO 26A 2)0 volta

Figure 5 - View of Test Turbine

Figure 6 ~ View of Test Turbine

and 149 amperes lbe generator ti ld was aepar tely

excited using direct current from a motor g n r tor ampt

(l$ p 4~8)

The power output of the generator waa dissipated in

the water rheostat (3 p 488-489) shown in Figures 9 and

10 The galvanized tank contain d water ot variable d pth

on an electrode ot cast iron m aauring 1bull x 1 x 1

In the initial installation of the turbine it was

intended that the power output should be measured with a

Prony brak bull For th purpoa68 or this teat it was decided

that the brake was too instable and the generator was

substituted The platform for raising the generator the

nee asary two teet for alignment was built out of available

material In this case heavy laminated wood blocks reiashy

torced with other timbers were used and bolted through the

concrete deck (11 Pbull 36-$7)

Due to the light concrete deck the lack ot mas in

the platform and the slight misalignment in the flexible

coupling ao e vibration waa encountered It seemed to

ncr aae linearly to a maximum at the speed of bout 750

revolutions per minute Above this speed no vibPation was

noticeable The vibration waa not se~ere and does not

appear to have materially affected the test results

26

B Intrumentat1on ~ eaeur1ng Devices

The pressure head at inlet to the turbine vaa meaave4

bymeane ot two )6 inch waterbullmeroury manometerbull connected

in series as shown in Figure 8

The terminal voltage ot the generator vas meaeured by

a laboratory voltDleter with a range to )00 yolta and callbull

brated to within 15 Yolta

The armature current bull and hence the line current was

measured by a laboratory ammeter with a range to 150 amperea

and callbrated to w1 thin o 7S amperes

Tae rate ot tlow was established by weight and time

meaeurementa The weighing ank has a capacity ot 121 000

poundsJ the weight belng indicated by Toledo direct reading

scales Timing was done with a hand atop watch with clivibull

aion ot 02 second

he ~ater level in the tailrace was dete~1ned by a

hook gauge lhie was read to the nearest 001 toot

The turbine and generator speeds were eaaured by a

hand tachometer The technique of almost cont1nuoua readbull

ings of the speed gave an error ot no more than 5 revolubull

tiona per minute

c Operational Procedure

Atter the water level in the aump was checked to

insure an adequate auppl7 the puapa were primed and

27

Figure 7 - Test Generator and Plattorm

Figure middot8- Instrument Board and Field Rheostat

28

started After venting they were valved for operation 1n

parallel

The motor generator set was started to supply the

field current and the circuit breaker was closed Water

wa added to the water rheostat to the level shown in

Figure 10 ~ field current wae minimized by cutting in

all the f ield resistance in the field rheostat of Figure 8

The l2 inch gate valve shown in Figures 5 and 6 waa

slowly opened and the turbine and generator brought up to

speed The 12 inch gat valve and turbine were vented and

the pumps were checked to insure neither had lost ita prime

lhe water rheostat offers very steady load 1f the

water level is essentially constant and the water temperabull

ture 1a fixed () p 488~89) In order to maintain this

constant temperature it was decided not to circulate the

water in the rheostat but rather to allow the water to

boil thua achieving the desired result A standing wave

was set up on the face ot the electrode by the boiling

action but a atable load was eatablished except at very

low water leYels where th11 agitation led to fluctuationa

in the line current

After putting the turbine and generator on the line

maximum power was dissipated in the rheostat by redueing

the turbine speed to between oSO and Soo revolutions per

minute Salt vas added to the rheoetat wat r to increasemiddot

29

Figure 9 - View of Water Rheostat

Figure 10 - View of Water Rheostat

Separate Field ExcitationFrom Motor-Generator set Compound Water-Mercury

---shy

re Manometer

I Q)

~ 0

~

Book Gauge

Open Channel

I

Slap Reservoir

Figure 11 - Wat~r Flow Diagram and Electrical Layout

31

waiting pe~iod ot perhaps an h~ followed

while the boiling point or the water wbulls reacbe4 During

this ti+ne the manometer was vented end eheoked electrical

measur1ng 1nstlUments were connected end the hook gauge was

adjusted tor elevation

It required about two- houtte tor the generator to reach

its normal operating tempe-ratu~e_ After the water in the

rheostat and generator had reached their operating temperabull

turea it was possible to begin the taking of data

The only vaPiable which was controlled wee the turbineshy

generator speed However the upper l1ut1t of safe line

current was slightly over 100 ampJilPampPes and the eireuit

breaker would open when the current reached lOS ~ere bull

Control was exercised by means ot regulating the water

level and salt 1n the water rheo tat and the res1stsnoe of

the tield rheost t~

The etfeet ot each type ot regulation on the three

variables is shown below

Volta Aaperebull Speed

Inc Dec Inc Dee~ Inc Dec

Wa~e1 Level Inc Dec~ X

X X X X

X

Salt Concentration

Inc Dec X

X X X X

X

field Resistance

Inc Dec

X X

X X

X X

32

Jlot all methods gave the ame amount ot change in a

given variable and a period of experiment and trial led to

the following scheme starting the rune with the lowest

turbine speed the water level was high with a high amount

ot salt and the field resistance was cut completely out

Aa it became necessary to increase the speed tor each

aucceasive run either cutting in t he field resistance

decreasing the salt concentration or lowering the Vater

level would produce the desired result However decreasbull

1ng the salt concentration had to be done Without a net

gain in water which led to a tluahing procedure that was

not particularly good because cold water was introduced

which required time to heat to the boiling point Cutting

1n additional field resistance was a good method but th1a

increased the amperage possibly to the point of opening

the circuit breaker Lowering the water level was aatiashy

factol1 until the level got too low causing the current

fluctuation previously mentioned Actually it turned out

that a combination of lowering the water level and cutting

field resistance in would carry the speed from ita minimum

to 1ts maximum value it the proper choice were made each

time the speed waa to be changed At the conclusion of

each aet of runs at a high speed the water level would be

low and the field resistance high

33

TURBINE

PAD AND DECK

TAILRACE

WATER SURFACamp

CONCRETE

DRAFT TU1B INSERTS

7 5( DRAFr TUBE

FLltJI ARIA

5~ DRAFT TUBE

FLOI ARSA

Figure 12 - Sketch of Draft Tube and Test Inserts

34

Figure 13 - View of Draft Tube Insert

Figure 14 - View of Draft Tube Insert

D c __ ~s_middot hedu_le of

A number was assigned to each run The fi~st number

applies to the draft tube tlow areas

1 bull 100~ flow area or 0~ oonatriction

2 - 7S tlow area or 2$ conatr1ct1on

3 SoC flow area or so~ constriction

The second number refers to the wicket gate openings

9 over gate opening

6 bull intermediate gate opening

4 bull one h lt gate opening

The third number 14entif1ea the location of the particular

1Wl in a set ot rona made at a given dratt tube tlow area

and wicket gate opening

fnua run number 1bull4bull10 would identity this as the

tenth run ot a set made at halt gate with 75 ot the draft

tube t1ow area

Rune w re made tor a g1yen dratt tube condition

Firat tor tull 41-aft tube flow area seta ot rune were

made for the overgate halt gate and intermediate gate

conditione An insert was placed in t he draft tube and

rune based on the same gate conditions were made tor the

7S~ draft tube flow area case The insert was then changed

to allow only $~ draft tube flow area

The inserts are sketched 1n Figure 12 and photographed

ln Flgurea 13 and 14 They oonaisted of circula~ segments

36

or l2 ineh plywood mount 4 on wooden legs 10 inches high

The 1nse7te were placed in position and secured by th use

ot a-clamps on the legs and the outside ot the bottom of

the draft tube The obvious disadvantage to this method

waa the neoeasity tor draining the water from the tailrace

tor a change ot 1naert The advantage vas of course the

simplicity ot design and construction

Chapter V

DATA-A Original Data

The normal data-taking crew consisted or two men

Assuming adjustments having been made to secure a certain

turbine speed (aee section on Operational Procedure) one

man would take semi-continuous speed readings with the hand

tachometer until a state or rotational equilibrium was

reached This could be only a period or two minutes up to

ten or tifteen minutes As soon as steady speed was

assured the data taking would begin The second man went

to the weighing tank Where a minimum ot three weighingamp

were made The requirement was to get three consecutive

readings such that the ditterence between tbe smallest and

largest time did not exceed 04 seconds The time to

collect a given weight ot water was then assumed to be the

arithmetic average of the three times He then went to the

hook gauge determined the hook elevation and then

recorded the data on the data sheets The first man meanshy

while had taken readings of the line voltage line current

and manometers and checked the turbine speed by multiple

readings During the length of the run all values were

38

checked to determine mean values for recording

The minimum length of one run was about five minutes

If one or more measure ants tended to drift during the run

all values wer discarded and a new run began as soon aa

qu111br1um was stabl1shedo

B -0-al_e_u_l_a_t--d Data

The h d on the tu~bine 1 defined by

($)

The maxtmwm velocity V4 was equal to about o8 tampet per

secon4 which makes it a negligible quantity when converted

into velocity head

An engineerbulla level was used to deterine the d1ffePshy

ence 1n elevation between the compound water-mercury manoshy

meter and the hook gauge Using this value the equation

for turbine bead becomes

where z4 is the hook gauge reading

The rate of flow 1 cent

w weight or water collected average time to collect

The inlet velocity v1 vas calculated by dividing the

weight rate or flow by the specific weight of water and the

)9

area ot ~e inlet pipe This was equivalent to dividing

the weight rate of flow by 490 Then the power input to the turbine is equal to

WHpin rri

10 (6)

Also

(P ~ut) Turbine

(P out) + Generator

(P lost) Generator

The power output of the generator is simplJ the

produot ot the terminal voltage and the armature (line)

curPent The power lost in the generator can be subdivided

into copper losses and stray power losses lo evaluate

these cunes based on losses of an identical generator

11leampsured by the Department ot Mechanical Engineering were

used The loss curves are reppoduced in part in Figures

15 and 16

Determination ot generator losses proceeds as tollowau

(1) From Figure 15 detem1ne the vo1tage drop in the

armature circuit using the temperatures of 1220 F and the

meaaured current

(2) The induced voltage is t~e sum of the terminal

voltage and the voltage drop 1n the armature circuit

() Entering the induced voltage and the turbine speed

into Figure 16 the stray power loss can be determined

(4) The copper lose can be evaluated from Figure 1$

using the measured current and the temperatlll-e of 1220 P

40

25 ~------~--------~--------~------~

U) -U) - 20

f-4 ~

-~ -gt 0

0

VOLTAGE DROP

~ - i -

- bullbullbull bull - -middot-middot -+ ~- + -t--+ ~ - ~ middotbull ~-~ middott- -+----- _ -4 middotmiddot- --~-+-t---r~~ ~--+t-t- - ---t-c-++~-ulf--

0 50 75 100

Figure 15 - Curves of Generator Voltage Drop and Copper Loss

41

1200

1000

800

600

800

0

0

~-

middot--~ 1shy --1 + bull l

100

I -

150 200

IIDOOED VOLTAGB (VOLTS)

Figure 16 - Curves of Generator Stray Power Loss

_ j

-bullshy -L---- shy middot -shy

250

- r

42

(5) The generator los os equal the sum of the eopp r

loss and stray power loss

~e efficiency or the turbine is taken as

etticiency u e =P out (8)Pin

~ample pound Determ1n1gg turbine Power Output

The following data are taken trom that ot Run 1-9-1

Line voltage 1040 volts Line current 870 amperesSpeed 355 revolutions per minute

The induced voltage 1a determined as follows

Line voltage 1040

Voltage drop 90 using Figure 15 with line current of 870 amperes and temperature ot 122 degrees)

Induced Toltage 1130 volta

The power output of the turbine is determined as follows

Generator output 90$0 (line voltage z line current)

Oopper loss 7 (using Figure 15 with line current of 870 amperes and temperatUe or 122 degrees)

Stray power lose 470 (using Figure 16 with speed ot 355 revolutions per miDUte and induced voltage or 1130 volts)

Turbine power output 9527 vatta

or turbine power output 1s 12z2 horsepower

43

The conversion of the calculated data to a constant

head is based on the conventional assumption of constant

efficiency regardless of turbine head For a constant head

ot 81 teet a purely arbitrary figure the tollowing relashy

tionships are ass1lJiled to be true

I ____L (9) (i)l72

(10)

For these two values the specific a peed may be combull

putedt

N t Jt VPt (11)8 243

Chapter VI

~RESULTS

A -Pr_e_ae_n_t_a_t_t_o~n g Reaultbull

Graphical presentation ot the results ot this te1t

are given as follows

Figure 17 -Turbine characteristics with 100~ dratt

tuba 1low area

Figure 18 - Turbine characteristics with 7S dratt

tube tlow area

Figure 19 bull Comparison ot power and etticiency at

over gate conditions between 100 and

75~ draft tube flow area

Figure 20 bull COZQparison of power and ettic1ency at

halt gate conditions between 100~ and

7S~ draft tube flow area

Figure 21 bull Comparison of power and etticiency at

over gate condition between 100~ and

So dratt tube tlow area

Figure 22 - Comparison in variation ot apec1t1c

speed between 100 and 75~ dratt tube

tlow area

50

45

20

-bull - 1--shy40

bull J-~ 30

~ ex

~ 20

~~ ~ -)q

I

~ - _

- -

10~ OF DRAFT TUBE FL(Jif AREA

CONSTANT HEAD OF 8l FEST10

POIER OUTPUT EFFICIENCY SPECIFIC SPEED

0 ~--------------_--------~------~------~ 400 600 800 1000 1200 1400

TURBINE SPEED (RPM)

Figure 17 - Turbine Char~cteristics with 100 Draft Tube Flow Area

50

46

-bulllle

~ 7 ~ OF DRAFt TUBE FLOW AREA

0 -~~-rl C05STAMT BEAD OF 81 mET 1J~

POIER OOTPUT ---+- ---o ~_H EFFICIDCY ~ I shy

bull ql SPECIFIC SPEKD - ~ -

bull ~ J 10 L rmiddotr- r- -

bullz- I

~~ 30 ~~--~----~~-

20 ~ ~ middot-shy

26

~~ 25

~0 ~r-----i (

Tbull -bullshy

400 600 800 1000 1200 1400

TURBINE SPEED (R PK )

Figure 18 -Turbine Characteristics with 75 Draft Tube Flow Area

47

EFFICIENCY 60

1-----shy

-~ 50~--~--~~-~middot middot middot middot r~-~----~~~~---4~-r~-~~gtt

II

POWER~ J ~ bull bull

u I

sH

40~------+-------+---- -~~--~~-~~~~

~----~rl 1 bull

I

I

0~--------------~------_------~--------

~ -OVER GATE CONDITION

COIJSTANT HEAD OF 81 FEET

0 o 10~ DRAFt TUBE

_-- _ 7~ DRAFT TUBamp FLON AREA II

10_~-----+--------r-------r----~~

400 600 800 1000 1200 1400

TURBINE SPEED (RPM)

Figure 19 middot - Comparison between 75 and 100 Draft Tube Flow Areas of Power and Efficiency at Over Gate Conshydition

48

t

bull --4 r ~- ~ middot~

70 1-----------+-~~~~~+middot ~ ~~ middot middot -~~--~~--------~~----~-+1

-~-

Atbull bull

lla-

60

amp0

40

20

10

oampOO

t _ - - ~-+- - -~-

l2 GATB COJIDITIOJJ

COJISTABT HJW) OF 81 JBET

o 0 lOQ( DRAFl TUB8 FLOI AREA

e-- - e 75 DRAFT TUBE FLOW AREA

800 1000

- r-

~

TURBIbull SPBIID (RPII)

Figure 20 - Comparison between 75 and 100 Draft Tube Flow Areas of Power and Efficiency at Half Gate Conshydition

49

60

50

-40

bull 30

IIQbull

20

10

0

400

- t - ~

EFFICIENCY

_J bull - bull bull

~ r r middot t -+ shy L -t -

OVER GAD COliDITIOI

CONSTABT BEAD OF 8l FBB

o o 10~ DRAFt TUBE FLOI ADA middot--- 5~ DRAF TUBE FLQPi AREA

600 800 1000 1200

Figure 21 -Comparison between 50~ and 100~ Draft Tube Flow Areas of Power and Efficiency at Ove~ Gate Conshydition

50

25

20

15

10

0

Figure 22

~- T -4 -t- -l --~-

t-~ I

middot --~- t ~---- _ __ _ + --

----~- --r-- --

~-=J-~-=-~ -==~ _ ~- -- ---f---1 - shy

CONSTANT HEAD OF 81 FEBT

o--o 1~ DRAFT TUBE FLltll AREA

75C DRMT TUBK FLCIJ AREAmiddot--middot-middot 600 800 1000

TURBINE SPEED (RPK)

Comparison of Specific Speeds for 75 and 100 Draft Tube Flow Areas

51

B Discussion 2 Result

Consideration of Figures 17 and 18 indicates the

overall eftioi ncy pattern or hill is significantly or

rounded for the 7$~ flow area than for the 100~ flow area

bia implies a greateP efficiency is possible at speeds

leas than or greater than design speed with an insert in

the draft tube However the muilDum efficiency is lemiddotas

Direct comparison at over gate conditions is made in

Figure 19 ~e same general trend is noted tor both the

etticiency and power curves for the 7$~ flow area case

The eurves show higher values at overspeed than do the

correaponding cWvea for the 100 flow area case It ia

not clear whether the curves have been shifted by the dratt

tube constriction or whether the curves simply bulge past

the normal curves at both overspeed and underspeed condishy

tions The power curves apparently peak near the aeme

point bullalthough maximum power is still obtained with the

normal draft tube area

For the comparison at halt gate operation shown in

Figure 20 a general improvement has apparently been made

by restriction of the draft tube flow area At every speed

the etticienoy and the power is greater for the restricted

tlow case The two ett1o1ency curves and two power curvea

are practically parallel throughout the speed range ot

teat

As the flou aroa i e decreased still farther a s1gn1

ticant change appears Reterr1ng to Figllle 211 tor the $0

flow area curves it a obvious that exit losses have

become excessive at the overgate condition because the

efficiency and power are everywhere leas than tor the case

of normal draf t tube area

Earlier it was pointed out t hat 1t the r esult s 1nd1bull

eated an increase in both power and ef tieiency- t hen it

could be assumed tha t the additional los s i ntroduced with

the draft tube insert is less than the diminished losses

due to leas shock losa and water passage losses For the

places where both the efficiency and power have been

increased we can assume that the insert has improved turshy

bine performance

For the places where the power haa been decreased

nothing can be said as to the elimination of ampbock loss

because the new lose present with the drat tube insert has

overshadowed any gains in eftecti Ve head upatJ-eam of the

insert

Near the peak of the efficiency hill howeve~ it may

be pointed out t hat shock loaa ie a minimum with a normal

draft tube and the insert merely adds an additional loss

with the resultant decrease in maximum efficiency tor the

7$~ flow area case

Perhaps the most s1gn1ticant set of eurves is shown aa

53

Figure 22 In this graph values of specific speed tor the

75 and 100~ flow area cases for both over gate and one

halt gate openings are plotted against turbine speed At

every speed and both gate openings the value ot specific

speed for th 75~ flow area case is greater than that for

the 100 t1ow area ease

Since the head is a constant for both situations this

may be interpreted in either of two ways trom equation

(11)

(1) For the same turbine apeed restriction of the

draft tube t1ow area resulted in greater turbine power

(2) For the same power amputput the turbine with 75~

draft tube flow area operated at a greater speed than did

the one with 100 flow area

Since the required diameter of a turbine varies

inversely with the speed the second interpretation could

be stated such that a smaller turbine could be used to

develop the same power output

Whether viewed trom the aspect of increased power

greater speed or reduced size the performance of the turshy

bine with reduced draft tube flow area is superior to that

with the nolmal flow are in the draft tube

The curve of specmiddotific speed versus turbine speed for

the so draft tube flow area case at over gate cond1t1ona

was not included in Figure 22 This curve lies below that

for the 100~ flow area c se at all speeds

In elaboration ot the second interpretation of Figure

22 attention is directed to the relative magnitudes ot

increased apee1f1c speed tor the two gate openings Assumbull

ing that the increase in specific speed implies a shift ot

the power curve to the right along the turbine speed scale

the power curve would be shifted more tor tbe halt gate

opening than tor the over gate opening

It thia trend could be extrapolated to the other gate

openings the tendency can be seen tor the line ot beat

speed to rotate toward the line of the operating speed as

illustrated in FigtU-e ) The advantage of this has already

been discussed

This particular turbine has a low specific speed tor a

reaction turbine Aa the rated value of apecitic apeed tor

reaction turbines increases the line ot beat speed departs

even more radically from the line of operating bullpeed It a

test similar to this were conducted on a reaction turbine

ot gleater specific speed it is pJobable t hat the rotation

ot the line of beat apeed would become more p~onounced

The scheme used in th1a teat had two obvious dr wbull

backs The first was the decision to leave all the wicket

gamiddottes installed tor all conditions ot the draft tube

These gates predominated in control of the tlow The

inserts added to the draft tube merely acted as auxiliary

55

contrGla

The aecond drawback was the choice or device to place

in the draft tube The reasons foll selection of this type

of device have been previously mentioned It is to be

anticipated that adaptation ot dratt tube flow control

would result 1n a better device for an actual turbine

installation Such apparatus might take the form of a

pneumatic bladder or a h7drau11oally operated variable

venturi section in the draft tube It is conceivable that

the gate as used in this test might be adapted also

Chapter VII

OONCLtJSIOfS

From the results of this test the following eonolubull

e1ona aa to the effect ot a variable draft tube flow area

on the performance or a r action turbine may be drawn

(1) The effect ot a variable draft tube tlow area 1a

generally favorable upon the operat1Gn ot a reaction turbull

bine because or the tendency tor the line or beat speed to

rotate toward the line ot operation This resulte in

better performance of the turbine at partbullloads

(2) he etf1o1ency eh111 tor the turbine beeomaa JDore

tlat at the top leading to a smaller max1JilWD effic1enc7

but e reater etticieney at other pointe of operation with

the insertion ot an auxiliary control ror the rate ot tlov

in the draft tube

(3) The power output of the turbine will increase at

over speed over gate conditione as well a at part gate

conditions with the proper amount or draft tube eonatr1cbull

tion or flow

(4) It is possible to eliminate at least partially

eddy type shock loss by tho introduction ot flow control

in the draft tube

BIBLIOGRAPBl

1 Addison Herbert A treatise on applied h-draul1cs New York Wiley 1954 724 Pbull

2 Allen o M and I A Winter middot Co111parative testa on experimental draft tubes Tranaact1ons ot the American ociety ot Civil Engineers 87t893bull970 1924

3 Barrows a E Water power engineering 3d ed ew York McGraw-Bill 1943 791 Pbull

Bovet G A Modern trenda in hydraulic turbine design4middot in Europe Tranaactions of the American Society ot Mechanical Engineera 75975bull993 1953bull

s Oreager William P and Joel D Justin Hydroelectrichandbook 2d ed New York Wiley 19$0 1151 Pbull

6 Daily Jamea w Hydraulic machinery Int Hunter Rouses Engineering hydraulics Hew York Wiley 19$0 p 8$8bull99

Daughertybull Robert L Bydraulie turbines ew Yorkbull7middot MoGrav-Hlll 1920 281 Pbull

8 Daugherty Robert L Inveat1gat1on of tne performance ot a reaction turbine ~anaactiona or the American Society ot Civil Engineers 7811270bull1304 1915

9 Davie L M Model and prototype testa Int Trend in hydraulle turbine practice symposium lranaactions ot the American Society ot Civil Engineers 1o63S3middot368 1941

lfJ Doland James J Hydro power engineering Hew Yorkbull Ronald 1954 209 Pbull

11 Gandy Theodore s and Elmer c Schacht Direct curshyrent motor and generator troubles operation and repair New York McGraw-Bill 1911 293 Pbull

12 Gibaon Arnold H Hydraulics and ita applications5th ed London Constable 1952 813 Pbull

58

13 Button s P Component loases in Kaplan turbinebull and The prediction of efficiency from model tests Probull coedings of the Institution or Mechanical Engineers168743-762 1954

14 Knapp R T~ Oavit t1on mechanics and its relation to the d sign or hydraulic equip ent Proceedings or tne Institution ot Mechanical Engineers 166150bull16) 1952

15 Langsdorf Alexander s Principles of direct curHnt mach1nee 5th ed New York r~cGrawbullH1ll 1940 746 Pbull

16 Lsrner Chester w Characteristica of modern hydraubull lie turbines Trans e~ions of the ~~erican Society ot Civil Engineers 66306-386 1910

17 Linsley Ray K Jr and Jobulleph B Franzin1 Eleshyments of hydraulic enginebullring New York McGrawshyBill 19$5 $82 Pbull

18 Mead Daniel w Hydraulic machinery llev York McGraw-Hill 1933 396 Pbull

19 ead Daniel w Water power engineering New York McGrawbullRill 191S 843 Pbull

20 Mockmore Charles A Part gate operation at water turbines Corvallis Oregon State College Department ot Civil Engineering 1933 11 numb leaves (Unpubshylshed typescript)

21 Mockmore Oharles A Flow characteristics in elbow dratt tubes Transactions of the Amez-ican Society ot Civil Engineers 103402middot464bull 1938

22 Moody L F Hydraulic machinery In c v Davis Handbook ot applied hydraulics New York McGrawshyHlll 1942 1082 Pbull

2) Ptau At-nold Hydrbullulie turbine handbook ld ed Milwaukee AllisbullOhalmers ManufactUIing Company 1948 70 Pbull

RheingalUI w J Recent developments in Francis turshybines Mechanical Engineering 74189-196 1952

25 Russell George E Hydraulica 5th ed New York Henry Holt 1942 466 Pbull

26 Safford A and E P- Hamilton American mixed tlow turbine and ita setting Tranampactions or the Amerieal Society of Civil Engineers 851237bull1)56 1922

27 bull Spannhake W1lhe1Dh Problems or modern pump and tur b1ne design Transactions of the American Society of Mechanical Engineers 56e22$-248 1934bull

28 Sutherlandraquo R A Better ethod or representing and middot tudying water turbine performance ~ansaetions ot thmiddote American Society of Mechanical Engineers 68t675bull 686 1946

29 Teats ot five models or draft tubes tor turbines Engineering News-Record Pbull 182-184 Aug 2 1923

30 White w M American hydztaulic turbines Mechanical Engineering S2t390bull39S 1930bull

31 White w M lhe hydraucGne rega1ner1 its developmentand appl1eat1ons 1n hydroelectric plants Meohanlobulll Engineering 43t37Sbull380 1921 middot

32 Winter I A Economic principlebull in designbull Int Trend in hydraulic urbin practice bull a ampoeiumTranaaot1ona ot the American Society ot Civil Engineerslo6332bull3S2 1941

33 Wiel1cenua G F Fluid mechan1ca or turbo-machineryNev York McGraw-Hill 1947 613 Pbull

APPENDICES

c

Appendix A

NOATIOB

A Angle between the absolute velocity vector and the tangent to the rwmer Subscripts 1 and 2 refel to entrance and exit ot the runner blade

B Angle between the relative 1elooity vector and the tangent to the rwmer Subscripta 1 and 2 refer to entrance and ezit or the runner blade

Angle between the tangent to the runner blade tip and the tangent to the runnel- Subscripts 1 and 2 reter to entrance and exit of the rt1rmer bladebull

Blade angle-gate opening conetant defined by equation (1)

e 09erall efficiency

g Gravitational acceleration assumed constant at 322 teet per second per second bull

H Turbine head detined by equation ($)

m Exit loss coeft1e1ent

Turbine speed expressed in revolutions per minute

Turbine speed under a constant head of 81 teet

specitic apeed of the turbine under a constant head ot 81 teet

p Power output in horsepower ot the tvbine

Power output of the turbine Ulder a constant head ot Sl teet

Pl- Pressure head at entrance to the tUlb1new

l1 Peripheral velocity ot the runneP Subacr1pta 1 and 2 refer to entrance and exit ot the JUnllampr blade

62

v Relative velocity reaulting trom the combination ot the absolute water velocity V and the runner periphshyeral velocity u Subscripts 1 and 2 refer to entrance and exit ot the runner blade

v] Relative velocity vector necessary to produce a tanbull gential entry into the runner blades

V Absolute water velocity Subscripts l and 2 refer to entrano and exit ot the runner blade

v2 Velocity head Subscripts 1 and 4 reter to the ~8 entrance to the turbine and the tail~ace wate~

w Unit weight ot water assumed constant at 624 pounda per cubic toot

V Weight rate ot flow in pounds per aeooncl

XX Velocity component ot ahook See Figule 2

Z Elevation head Subscripts 1 and 4 reter to entrance to the turbine and the taibace water surfacebull

Appendix B ORIGINAL DATA-Run

lfwnber

0-4-1 0-4-2 0-4-3 o-4-4 o-4-S o-4-6 0-4-7 0-4-8 0-4-9o-4-lo o-4-11 o-4-12 0-4-13

o-6-1 o-6-2 06-3 o-6-4o-6middotS o-6-6 o-6-7 o-6-8 0-6-9 o--6-lo o-6-11

Speed

rmiddot2middotbullmiddot(1)

336 38$ 451 S$9 620 669 6lt)$ 120 787 860 932

102imiddot109 bull

352 355 443middot 543middot 620 654AJs32

911 1001 1111

~essure Head rt (2)

410 410 416 426 431 43-7 439 44-9 452 467 482 soo $1 bull $

350 351 35middot7 )66 37-9 37-9 392 41 bull 3 43middot3 460 489

Elevation Bead

fjj $7 $7 $7 $7 $7 $7 51 57 5-15858 $8 58 56 56 $6565656 51 575As5a

Velocit Head

flj 07 07 07 06 06 06 06 os 05 os0404 03

09 09 oa o8 o8 os 07 07 06 o~o

Total Head rt ($)

47middot4 4A44 o 489 49-4 soo $02 $11 $14 $29 5imiddot45 2 576

41 bull $ 416 421 430 44middot3 44middot3 456 47-7 496 523551

Plow

lbtjec

326 324middot317 311 306 30029middot28 middotmiddot middot 386 275middot260 240 218

359 36~35 bull 349 345middot 339 330 318 300 273 240

Line Potential

vyqjbull 1060 1220 ~-0o 1920 2150 2000 2$60 2000 1940 18)015io11 o

1000 1100 139bull5 1760 1925 16$0 1620 1610 1540 1330 870

Line Current

amlscs 960 900 830 740 730655 70bull 0 530 660 600 5imiddot54 6 )60

982 930 860 780 ~3-545

79-5 74-5 670 560 370

P

Appendix B ORIGINAL DATA (Continued)

Run Number

Speed

Pbulltmiddotbullmiddot )

leasure Head ft(2

Elevation Head tt(J)

Velocity He-dfmiddotj

Total Bead tt($

Flow

lbstsec( )

Line Potential vo~ta( )

Line Current

amjs (sect

0bulllt)-1 0-9-2

3ll6 398

28o ~~1

$6 56

1o 10

346 347

390 365

1ooo 1190

aao 835

0-9-3 0-9-4 o-9-S

472 565 632

292 305 312

$6 s6 56

10 o9 o9

)$8 J7~o 37~7

381376 37o

1)6614oo 141o

820 ass ass o-9-6 0-9-7 0-9-8 o-9-9 0middot9-10

680 120 762 844 920

)24337346 366 390

56 $6 56 57 $7

09 os o8 oa 07

)89401 410 431454

367~ 357348 34o 322

1400 1J6o l36o 1310 1170

843 820 7957So 67~0

0-9-ll 0-912

1001 1100

41 bull 7 45-3

s 7 6~0

06 os 480 $18

299 268

980 65$

560 36~5

1-4-1 1-4-21-4-l1-4shy1-4-5 1-4-6 l-4-7 1 4-8 1-4-9 1-4-10 1middot4-ll 1-4bull12

354middot452 562 62q 674shy102 752 760- 863 932

1022 1100-

)82389 4014oa 416 41--7 423 428 44-2 45-7 486 49-2

51S757 51 5-7 5middot15zs sa $8 58 59

07 07 06 06 06 06 06 os o bull o 04 o J

446 45-)46middot4 471 ti7-9480 q86 491505 $19 548 55-4

)28 320 311 306 300 295 291 286 269 2582iimiddot21 bull

1080 14Lo 1550 153-5 1470 141-0 1385 1310 1310 1230 1120 855

970855 875 91-0 94~0 975 966 995 860 77-S 610 4fo

0 ~

Appendix B ORIGINAL DATA (Contirmed)-Run Speed Pressure Elevation Velocity Total Flow Line Line

Number Head Head Head had Potential Current rtjjmbull t~ bttec vyfs am~a12) ( ) ti fli 8

1-6-l $6 33$ $6 0bull9 400 364 1100 93 0 1-6-2 41 34laquo2 $6 oa 406 JS7middot iios a5s l-6-3 500 3~0 5bull6 os 356 1 1 o aos 41middot~1-6~4 35bull4 5-6 oa 41middot 352 16~0 82 0 5~1-6-5 5 bull 36_2 Sbull6 08 42bull6 349middot 161 ~ 0 86~0 1-6-6 622 366 $6 oe 43bull0 345middot 158 0 88~$ 16-A 649bull 37bull1 56 os 43-S 342middot 1570 895 1~- 386 57 07 46-0 192 ) 125A44 333middot 1-6-9 3) 404 5middot1 07 468 317 1620 675 1610 911 42-4 5-7 o6 48-7 298 168 0 61 0 1-6-11 999 451 56 os Sl ll 276 ~2-0 530 1-612 1115 485 58 04 54middot7 238 90 )3 0

1middot9-l 355 279 56 10 )45 385 1040 870 1-9-2 399 28J $6 10 )49 38$ 1140 86 5 l-9-3 ~ ao 291 56 ~0 35middot1 J8J_ JJ6o 815 1bull9-4 579 303 56 09 )68 375middot J4JO 830 l-9bullS 40- 313 )6 09 31middot8 370- 1460 82~0 1-9bull6 679 2) 56 09 3 bull8 364middot 1670 710 l-9-7 682 319 56 o9 384 ) 62 1460 79 5 l-9-8 724 33middot5 56 o8 399 3$6 bull 1480 76 -5 1-9-9 762 34middot3 $6 0 bull 8 407 )48 14910 13middotS 1-9-10 833middot )60 5middot7 os 42$ 339 144$ 686 1-9-ll 926 39middot1 5-7 07 455 318 1290 600 1-9-12 1000 41middot3 0-6 476 298 1115 510$ ~ 1middot9-13 1105 452 s o4 $14 2$6 710 )10

~

Appendix Bt ORIGDIAL J (Continued)

Run Speed Pressure Elevation Velocity Total Plow Line Line Number Head ltead Head jlamp$d P()ten~ibulll Current

r~~~m ft ft lbs~seo voltattj rgj twimiddot t 1 t2gt lt3 ou t ( rt

2-9-1 384 289 S 6 10 35 5 1400 1170 810 2-9-2 443middot 29$ $6 ltimiddot9 360 379middot 11(0 87$ 2-9-J 536 30bull 3 sc 09 )68 374middot 1)40 84 bull) 2-9-4 571 306 $6 09 3~1 372 120bull 0 955 2-9-5 623 316 S6 09 J l )6S UJSo 77$ 2bull9-6 669 327 S6 09 )92 )61 1240 905 2-9bull7 712 )39 56 os 40-3 351 12(0 86 bull0 2-9-8 ~5$~ J48 56 oa 412 348 1290 81 bull ) 2-9-9 04 )63 56 oa 42-7 339 12ltJO 76$ 2middotmiddot9-10 8$2 376 5middot1 07 440 33~- ~ o 710 2-9-11 955 394 5-1 o6 457 300 1100 506 2middot9-12 1000 421 $7 06 48middoti 295 1020 $18 2-9bull13 110~ 463 56 05 $2 267 620 3~0

oshy0

Appendix Gt CALCULATED DAgA

Turbine Run Generator Generator Turbine Turbine Efficiency Turbine Turbine Specit1c

Number OutputKWlt21

Loa~Jes KWlol

Outut K bull (H)

Input RP 12)

middot Percentlt13gt

Speed r~Jmiddot(

0ltput HP ~1

Speed r-m

( 6) middot

o-4-1 0middot4-2 0-4-3 0-4-4 0-4-5 0-4-6 O-qmiddot7o-4-8o-4-9 0-4bull10 0-4-11 o-4-12

1018 1o9a 1220 1)62J40214oa1J4oo 1357 1320 1164 997 718

046 o59 071 092 096 1071oo 134 104 100 109 107

14261sso 17)01948 2008 20322011 1999 19 09 1708 14-84 11o6

281279 27-7 276 215 273271 268 268 26h 258 24-5

soa 555 62$ 705 7)1145 742 74-6714645 51s 45-1

440 sos 585 720 195 sso sao 9$$ 985

1065 1135middot 1230

318 357 319 416 422 419412 39middot9 378 324 260 191

102 12bull4 148 191 21bull 3 22o 233 249 24924middot9 238 221

0-4middot13 418 104 699 228 306 1300 117 18)

o-6-1 982 045 1376 271 $08 496 376 124 o-6-2 o-6-3 G-6-4o-6-5 0-6-6

1023 1200 13 73 J415 139h

051 0middot66 oaa ()bull 96 088

14-39 1696 1958 2026 1986

276 27middot4 273 278 274

$20 61 8 717 7)0726

q95615745 8)5685

390 ll5middot3 sos soo 490

127 170 218 243 2$$

o-6-7 o-6-8 o-6-9o-6-lo

1288 1199 1032 7-45

o9o 094 09$ 096

1846 1733 1511 1128

274 276 271 260

67S 629559 43middot4

980 1085 1165 1245shy

436 )83316 21bull 7

266 276 270 239

0-6-11 322 1oo 566 2141 2JS 1350 101 177 0 --4

Appendix C CALCULATED DAlA ( Continued)-Run

Number Generator Generator

Out2ut Losaes xw LW- 12gt (lO)

Turbine Out2ut

ltPlJ

Turbine Inat lfP Jig)

Etpound1e1ency

PireentDl

Turbine Sed x-~m( 1

Turbine OutEut RPJl)

Turbine Specific

SeeedrIbullntbull

( 6)

o-9middot1 0-9-2 0-9-3 o-lt)-4 09-$ 0bull9-6 0-9-7 0-9-8 0-9-9 0-9-10 o-9-11 0-9-12

aao 994

111$ 1197 1206 1180 11)21081 982 784 5-49 2)9

0middot45oss o6$ 070 07$ 0-77 (l77 or~ o s06o 8 096

123~ 1402 1$80 1698 17bulllS 168$ 16bull18 ~middot5430 1151 a~J4 9

24middotgt24middot3248 25~25 260 260 259 267 266 26middot1 2S2

sos 577 63-7 671 676 650 621 60036J4

327 178

$) 610AlO 3$

92S 980

102$ 1070 1157middot 1230 1300 137Smiddot

44middot4 soo 523 ssomiddot 540so6 46-5 432 368 274 18~8

J46 176 21-1 255 2802s_A 28 289 288 265 231 168

1-4-1 1-4middot2 1-4-3 1-4-4 1-4-5 1-4-6 1-4-7 1-J-8 1-4~9 1-4-10 1-4-11 1-4-12

10bull48 1231 13-S6 1397 1)821375 1))8 1303 1127 953 683) 51

048 067 o7A07 0 bull79 oa1 oss o bullao osa 0lt)0 096 099

J468 1740 1921 1978 1958 19$1 1911 lSSi162 1)98 1045

603

266 264 262 262 261 2512$7 2$6 24middot7 24-3 233 217

551 660 13middot3155 75-6 7~-97 middot4 72$ 67 51middotJ 44middot9 21middot1

475 605 A4220

875middot 910 970_

1000 1090bull 1166 1243 1330

5816

44middot444middot5 430 427 412 392 329 273 188 l0-7

117 101 204 22$ 2)7245 2562sa 257251 222 179

a-C))

Appendix Ct CALCULATED -DATA ( Ocntinued)

1-6middot1 1023 o$2 14-41 26S 505 41~6 26~

54middot5 13middot3l-6-2 1201 067 1boo 625 47-9 17shy~middot41-6bull3 1296 oA9 1 middot43 26 9 700 so5 20bull 4 l-6-4 l3j5 o 0 19~09 268 71bull3 A5o 514 222 1-6-5 1) 5 o81 19(gt4 271 725 51-5 238 l-66 1398 081 198) 27-0 736 8 S13 252~-middot l-6j 1405 083 199i 211 733 885 $middot06 2$9 l-6 13middot9~ 103 2amp 0 279 71 8 985~ 467 ~-69 1228 1 bull 02 17-SS 270 661 109$ 407 ~3~ l-6bull10 1025 100 lSll 26i 573 1175middot 27~S32middot~l-ampu 153 1-00 llft3 26 444 1270 22 24bull8 1bull6-12 294 100 52a 231 22 3 1360 95 172

1-9bull1 904 048 1275 2J4Z $28 S4$ 459 1$2 1-92 98$ oss 13-92 24middot4 57-0 6JO 49bull1 176 1-9middot3 1110 066 1$76 24middot9 63middot4 I2o 536 21-7 l--9-4 1187 072 1685 251 66$ 5 $$ bull 0 261 1middot9-5 llltJ7 1710 25middot4 67-3 93$ 536 28~20-671middot9-6 1186 o 8 1708 25-7 67) 980 $15 2691-9- 1161 oBo 1660 2$middot3 6$6 990 508 29-1 l~- ll-32 oB) 16sect0 2$8 632 1030 471 291 1-9bull9 109$ oa5 2$7 614 1075 29S~middot 0 4imiddot41-9-10 9~91 oas 262 S$1 1150~ 3 o 292 1-9-11 o9o u57 12JiO 21gt 26-77middot74

-45 26sect ~middot91-912 $69 091 sas 25 middot3 1)0$ 196 2J-8 1-9-1) 220 098 426 2)9 178 1390middot 84 16 6

0 0

Appendx C CALCULATED DATA (Continued)

Turbine Run Generator Generator lurbine Turbine Eft1e1eney Turbine lurbine Spee1f1c

Number Output Losses Outit Input Speed Output SPed middot k_-V KW R _ H_bull_P Percent r Thm HP rpm_ (9) tlo) 11) middot (12 _) (lJI ( ) (1$ (14)

2-9-1 9--46 055 1)62 258 528 580 164 2-9-2 1024 056 248 58 4 665 4 9 191iimiddot48 4~middot0 2-9-3 1132 067 05 2$0 641 795 52q 237 2-9-4 1148 065 1027 2$1 -~8 845 525 252 2-9-5 11 77 oso 16-83 253 6 910~ 522 270 2-9 6 1122 071 1600 251 622 960 47-5 2722-9-A 1092 015 1562 257 608 1010 445 2z12bull9- 1052 079 1514 261 580 1060 41middot7 2 2 2middot9-9 986 o82 ]429 26) 542 1105 372 277 2-9-10 915 086 1340 268 500 1160 334 27-6 2-9-11 638 087 972 254 )81 1270~ 229 250 2-9-12 )28 090 828 259 )19 1295 179 226 2-9-13 192 094 383 2$ 6 150 1370 7 3 152

-3 0

Page 14: The Effect of A Variable Draft Tube Flow Area on the

Ohapter II

DISCUSSION ~ TURBINE LOSSES

A General

lhe head that 1a actually utilized by the turbine 1a

less than the effective bead as defined by equation ($) by

the amount that 1a lost due to mechanical and hydraulic

reasons

Mechanical loaaea are a function or the turbine 8p$ed

fhis ia not a lineaz- function but varies eomewhere between

N and N2 (3- Pbull 224)

Hydraulic losses encounteled in turbines ma- be subshy

divided aa to the location or occurrence (3 p 225-227) aa

fOllOW$S

(1) Penstock and scroll case

(2) Wicket gates

(3) Between wicket gates and turbine runner

(4) Runner passages

(5) Runner exit into draft tube

(6) Draft tube and

(7) At exit from the draft tube

The flow in the penstock scroll case wicket gates

runner passages and draft tube may be envisioned as

examples of flew in conventional pipes elbows and convergbull

1ng passages If this comparison may be made it could be

assumed that the losses encountered in these locations

would be proportional to vn ~ value ot N is normally2g

aesU111ed to be 2

he losses encountered between the wicket gates an4

the turbine runner and exit lossos are special cases which

will be discussed separately

B Shock toes_

The flow betwe n the wicket gat outlet and the runner

blade entrance is or particular 1nt rest because no direct

comparison vith common flow situations is obvious

Conaider the vector diagram (7 Pbull 7576) in Figure 2

The veetoo v1 is the absolute entering velocity of the

water and is fixed in magnitude and direction by the setbull

ting or the wicket gates The vector l11 1e the peripheztal

velocity of the runnel which tol any given turbine 1e

dependent only upon the turbine rotational speed The

combination of these two vectors ylelda the third vector

v1 which is the relative entering velocity ot the water

nere is only one setting ot the wicket gates for a

given turbine a peed that will produce an angle B1 which

coincides with the blade angle B1bull At other gate settings

the vector v1 will rotate and change in magnitude in such a

9

t ehion that B1 will beoome either greater or 1 sa than B1bull Th1 give rise to tbe phenomenon term d shock loasft

If B1 1a greater than B1 the relative ent ring veloebull

ityt v1 will have a compon~nt opposing the forward motion

of the runner The shock loss could be typified bullbull that

occasioned by direct impact or the water 0n the blade- If

E1 is lese than a] the vector l will overshoot the blade

and the flow will tend to eddy around the forward portion

or the blade tip

The shock loss can then be either due to impact or

eddying flow Since the area norm 1 to the radius at outlampt

of the w1eket gftee is essentially equ 1 to the area normnl

to the rad1u~ at the inlet to the turbine runner the combull

ponents ot vl and vl perpendicular to ul will b approxishy

mately equal This leads to the conclusion that xxbull ~epresenting the shock vector 1 parallel to Ulbull

For either the impact or eddy case the trigonometric

law of $1nee leads tot

XX

bull ul - sin (Bi-Al) vl eln Bi

It it 1a assumed that the energy lost in the shock 1a

the Telocity head ot the shock component XX then

10

VELOCITY VECTOR DIAGIWI

TYPES OF SHOCK LOSS

xbull X

IMPACT BDDJ

XX 1a Teloc1t7 caponent ot shock

Figure 2 - ~bine Runner Vector Diagram$ and Shock Loss Diagrams

11

2 shock loss (XX gt2g

C =sin (BimiddotAl)Let (1)sin Bi

(UlmiddotCV1)2Then shock loabull (2)- 2g

For a given gate opening C ia a constant ranging

from about 14 to 10 For a well designed wheel it is to middot

be expected that C would be approximately equal to U1V1

at rated conditions ie at point of maximum efficiency

This point will occur in the neighborhood of 3~ to 78

gate opening for moat turbines For overgate conditions

the angle A1 becomes larger so the value of C would

decrease For gate openings below rated conditions t he

angle A1 decreases and C would decrease One could expect

a fairly uniform decrease in t he value of C as the gate is

closed from t he overgate position

The velocity v1 is approximately constant for any

turbine speed since the area and rate of flow both decrease

fairly uniformly However for a given gate opening the

velocity V1 will decrease with increased turbine speed

From the foregoing comments and equation (2) the

following trends can be established

(1) For constant turbine speed the shook loss curve

will be close to parabolic in shape concave upward and

have its maximum near t he point of complete gate closure

--

12

and its minimum near the rated gate position

(2) For conatant gate opening the shook loss curve

will approximate a symmetrical parabola with its vertex

the point of minimum loas located at the rated condition

of operation (7 Pbull 79)

c Exit Loas

It can be seen from Figure 2 that the exit loss from

the turbine would be v222g if no draft tube were present

The addition of a draft tube permits the gradual reduction

of velocity by an increase in cross sectional area between

the exit of the runner and the exit from the draft tube

The exit loss and the frictional loss encountered in

the draft tube may be placed together in the expression

m va2 (3)Exit Loss ~---2g

For the ideal case of no friction in the draft tube

m is equal to the square of the ratio of the area at exit

from the runner to the area at exit from the draft tube

In an actual turbine installation however friction

will change the value of m (7 p 84-85) to somewhere

between that for the ideal case and a maximum ot 10

In the interest of maintaining a minimum exit loss

the turbine should be designed and operated so the velocity

V2 will be minimum This will occur when the discharge

13

vector is at right angles to the tangent to the runnerbull

ie the angle A2 1e ninety degree bull It ia to be expected

that this condition will be tultilled near the design con~

d1t1ons ot the ~bine

Current design praetiee 1 to have a small component

ot v2 in th$ direction of turbine rotation at rated condibull

tion$ ltS p 938)

For a constant turbine speed the d1seharg or exit

loss is ess nti lly a constant

For a constant gate opening the exit lo s curve is

aptrroximately a symmetrical pa~abola with ita vert x the

point or minimum loss located at a slightly lowe~ speed

th n the turbine rated speed (7 Pbull 79)

Chapter III

PROPOSAL OP ALlERMAlE MFTBO 0 CO TROL-A lz ~ Location 2 Control

Thua tar only practice and theoretical aspects appemiddotrbull

taining to present day turbinea have been d1acuaaed It

haa been presented that control over the ~bine ia ezerbull

oiaed b y manipulation of the wicket gatea located 11101led1bull

ately preceding the runner These gate - upon rotation

modify both the magn1tu4e and the direction ot the entering

velocit7 Moreover it has be n shown that a simultaneous

change in these two variables leads to inefficient operabull

tion by the introduction of shock loss he farther the

point of operation a from the rated conditione the more

aerioua ia the ahock loss encountered

Any attempt to better turbine pertorance at other

than rated conditione and tbne flatten the top ot the

etticieney hill8 must concentrate upon the lessening ot

the ahock loaa It 1a a aumed that 1 provement in the

scroll case gates and runners would lequ1re sueh pertecbull

tion 1n machine work and metal$ as to be prohibitively

expensive

It ie surmised that any move to elblinate eYen parbull

tially the shock loss would require separate control ovel

l$

the flow and gate exit angle Since it is improbable that

d1~ect1on could be controlled at any location other than

where the gatea are situated in current turbines it will

be assumed that guide vanes will be necessary regardlesa or the method used to control the rate of flow

The primary purpose ot th se guide vanes 1s that or control over the direction ot the incoming water They

should be free to rotate in much the same manner as ordibull

nary wicket gates in order to exercise control over th

turbine speed

If the rate ot tlov is to be controlled elsewhere it

must be modified either in the penstock or the draft tube

Devices that could be used are standard valves gates

variable orifices variable venturi sections and associated

flow regulating schemes

Alauming it were decided to locate such a device upbull

stream of the turbine it would be necessary to allow disbull

tance tor the flow picture to become reestablished prior to

entry to the turbine A contused flow making transit of

the turbine passages would only contribute additional loesbull

ea Such a distance allowance would be perbapa 20 to So

diameters (2$ Pbull 119-123) In large penstocka th1a would

repreaent a considerable distance Which from the viewbull

points ot convenience and control would be undesirable

Attempts to ascertain the effect or additional tlov

16

reduc ion at the wicket gatctsmiddot wae ade 1n the lfadraulioe middot

Laboratory of Oregon St middot te College in 1933 (20) Three

d1tterent thode ot reducins the tlow were t~ied

(l) Locking in the cloeed position pairs or wicket

gatea located opposite to eaeh o~er on the -periphery ot

the wheel

(2) Locking adjacent gates in an open position by

inserting blocks of wood between them and

()) Suocess1vely looking adjacent gates in the closed

position

The results indicated a arked reduction in both power

and efficiency when compared to the curves tor normal gate

operation However it was demonstrated that it was poae1bull

ble to ahitt the power and tfieiency curve ill relation to

turbine apeed lbis important feature will be diacussed

later

ihe main conclusion of the investigation was that conbull

trol by the conyent1onal wick t gates was auper1or to other

methode egtt control exercised at the gates the aelvebullbull

It would app$ar that the bebullt location tor flow conshy

trol would be in the draft tube since none of the objecbull

tiona prev1ously mentioned wou~d eziat there

As bas been stated previously the sole object or the

17

18

turbine is to produce power as etfic1ently as possible

The equation tor the power output of a turbine () Pbull 227)

PaWHe HP (4)55o bull bull Assuming the head 1a constant and a g te located in

the draft tube decreases bhe rate ot flow the power eu

only be increased if the etticiency increases

The ettective head Gn the turbine 1s conventionally

d r1ned as the difference between the auma ot the elevashy

tion head pressure head and velocity head at the entrance

to the turbine casing and the tailrace ($ Pbull 872)

lt ie recognized that the theoretical treatment ot

shock loss as given is highly approximate and serves only

to dictate certain trenda For example the area at xit

rom the wicket g tea CfUl be measuPed with some exactness

but there exists no guarantee that the wateP particles will

complet-ely fill the apace oz- will exit at the establiahed

g te angle The same can be said of the exit trom the

runner blades AssUIlptiona were implied which would indishy

cate that all water particles passing a given croea section

ampH traveling at the same velocity in the same direction

the e alone are autt1c1ent to show 11m1tationa in a theoretbull

1eal approach to the problem

Assume a turbine with ordinary wicket gates tor oonbull

trol compared gainst the same turbine with a gate in the

18

draft tttbe tor supplampment1ng control or the rate ot rlow

Let it also be assumed that the two turbines are opershy

ating at the same point It 1s desirable to predict relabull

tive performance of the two turbines 1 this point of

operation is such that edd7 s hook loss ot reasonable proshy

portions is present in the fir t turbine

~ tull erteot of the shock loss will be exper1 need

by- the fir t turbine

lhe second turbine will derive certain advantages 11

the gate in the draft tube is adjusted to reduce the tlov

1n the proper amount Since they vary a the square ot

the veloo1t7bull the lossabull in the aeroll case wiomiddotket gate

and runner passages will decx-ease aetet-r1ng to Figure 2 1

it can be seen that a decreased velocity v1 w-ill reduce the

eddy shock losa

The ent loss in the dJtaft tube of the second turbine

will be the sum ot the tr1ct1onal loss and the velocity

head at ex1t The velocity head dissipated will be greater

due to the closing action or the gate but the reduoed

t~ictional loss which ia a tunction ot the rate of tlow1

will partially balance this

It 1a entirely possible that the net reduction in

losses in the second turbine will lead to a greater ettibull

oiency and more power output than 4eYeloped by the first

turbine

19

In Figure 3 the plot ot power output against turbine

speed for Curv A~ represents the typical family of curvea

tor a reaction turbine Th b st sp ed is the locus ot

points connecting maximum eft1oiency at each gate opening

The operating speed is the coZUJtant turbine apeed which

passes through the point ot maximum efC1ciencr of the turbull

bine The plot of turbine efficiency against power output

for Curve A is also ahown

It the turbine with flow regulation in the dratt tube

oan demonstrate superior power and efficiency at part loads

the effect would be the same as a shifting or the power

curves toward the condition shown fop Curve B 11 Thisbull

illustrates th ultimate case of the uperpoait1on of best

and operating speeds It will be noted that the pet-form~

of the turbine ot Ourve Bu 1a better than that of CUrve

A at part loads because of ita ability to sustain a relabull

tively high etticienoy ovel a Wider range of power output

o Reguireaegts tort Test Velitication

It is desired to deterra1ne the effect on the turbine

performance b) the addition of a gate in the dratt tube

Th step in the teit will bet

(1 To determine the power output and efficiency ot

the turbine tor wicket gate settings above and below rated

conditione for a wide range ot speed

20

CURVEAbull

TURBINE SPSBD TURBID SPEKD

POIBR OOTPOl

Figure 3 - Turbine Performance Curves

21

22

(2 peat (l) with the gate installed in the drat

tube

(3) middot Converting middot all data to a constant head compare the

powere and effioiencies at the same wicket gate setting and

turbin speed tor the two cbullses

If the ddition or the gate indicates an improvement

in power output and efficiency and the powe~ curve shifts

to the right along the turbine apeed scale the advantage

ot draft tube con~ol of the flow will hav been demonshy

strated

Chapter IV

A E9J11pment

ih turbine used in this test is lJ 5 1nch Pelton

reaction turbine with a rated output ot 30 horsepower under

a head of 56 feet at a speed ot 720 reYolutiona per minute

Views of this turbine are hovn in Figures S and 6 The

turbine is installed on a concrete pad located over an open

channel in the Hydraulics Laboratory at Oregon State Colshy

lege The date of manufacture of this turbine was 1915

The water was delivered to the turbine from a sump

reservoir by two pumps operating 1n parallel Each pump 1a

an 8 inch Pelton double suction centrifugal pump witb a

rating of l$00 gallons per minute at a head ot 75 teet with

a speed ot 1175 revolutions per minute Tbe inlet tlange

ot tne turbine is $pprox1mately 18 feet above the center

line of the pump

A direct current generator was coupled to the turbine

to receive tne power d veloped as shown in Figures 4 and 7 The generator is a Spr gue Electrodynamometer rated at SS horsepower with a speed range of 7$0 to l$00 revolut1one

per minute The classification is type LO 26A 2)0 volta

Figure 5 - View of Test Turbine

Figure 6 ~ View of Test Turbine

and 149 amperes lbe generator ti ld was aepar tely

excited using direct current from a motor g n r tor ampt

(l$ p 4~8)

The power output of the generator waa dissipated in

the water rheostat (3 p 488-489) shown in Figures 9 and

10 The galvanized tank contain d water ot variable d pth

on an electrode ot cast iron m aauring 1bull x 1 x 1

In the initial installation of the turbine it was

intended that the power output should be measured with a

Prony brak bull For th purpoa68 or this teat it was decided

that the brake was too instable and the generator was

substituted The platform for raising the generator the

nee asary two teet for alignment was built out of available

material In this case heavy laminated wood blocks reiashy

torced with other timbers were used and bolted through the

concrete deck (11 Pbull 36-$7)

Due to the light concrete deck the lack ot mas in

the platform and the slight misalignment in the flexible

coupling ao e vibration waa encountered It seemed to

ncr aae linearly to a maximum at the speed of bout 750

revolutions per minute Above this speed no vibPation was

noticeable The vibration waa not se~ere and does not

appear to have materially affected the test results

26

B Intrumentat1on ~ eaeur1ng Devices

The pressure head at inlet to the turbine vaa meaave4

bymeane ot two )6 inch waterbullmeroury manometerbull connected

in series as shown in Figure 8

The terminal voltage ot the generator vas meaeured by

a laboratory voltDleter with a range to )00 yolta and callbull

brated to within 15 Yolta

The armature current bull and hence the line current was

measured by a laboratory ammeter with a range to 150 amperea

and callbrated to w1 thin o 7S amperes

Tae rate ot tlow was established by weight and time

meaeurementa The weighing ank has a capacity ot 121 000

poundsJ the weight belng indicated by Toledo direct reading

scales Timing was done with a hand atop watch with clivibull

aion ot 02 second

he ~ater level in the tailrace was dete~1ned by a

hook gauge lhie was read to the nearest 001 toot

The turbine and generator speeds were eaaured by a

hand tachometer The technique of almost cont1nuoua readbull

ings of the speed gave an error ot no more than 5 revolubull

tiona per minute

c Operational Procedure

Atter the water level in the aump was checked to

insure an adequate auppl7 the puapa were primed and

27

Figure 7 - Test Generator and Plattorm

Figure middot8- Instrument Board and Field Rheostat

28

started After venting they were valved for operation 1n

parallel

The motor generator set was started to supply the

field current and the circuit breaker was closed Water

wa added to the water rheostat to the level shown in

Figure 10 ~ field current wae minimized by cutting in

all the f ield resistance in the field rheostat of Figure 8

The l2 inch gate valve shown in Figures 5 and 6 waa

slowly opened and the turbine and generator brought up to

speed The 12 inch gat valve and turbine were vented and

the pumps were checked to insure neither had lost ita prime

lhe water rheostat offers very steady load 1f the

water level is essentially constant and the water temperabull

ture 1a fixed () p 488~89) In order to maintain this

constant temperature it was decided not to circulate the

water in the rheostat but rather to allow the water to

boil thua achieving the desired result A standing wave

was set up on the face ot the electrode by the boiling

action but a atable load was eatablished except at very

low water leYels where th11 agitation led to fluctuationa

in the line current

After putting the turbine and generator on the line

maximum power was dissipated in the rheostat by redueing

the turbine speed to between oSO and Soo revolutions per

minute Salt vas added to the rheoetat wat r to increasemiddot

29

Figure 9 - View of Water Rheostat

Figure 10 - View of Water Rheostat

Separate Field ExcitationFrom Motor-Generator set Compound Water-Mercury

---shy

re Manometer

I Q)

~ 0

~

Book Gauge

Open Channel

I

Slap Reservoir

Figure 11 - Wat~r Flow Diagram and Electrical Layout

31

waiting pe~iod ot perhaps an h~ followed

while the boiling point or the water wbulls reacbe4 During

this ti+ne the manometer was vented end eheoked electrical

measur1ng 1nstlUments were connected end the hook gauge was

adjusted tor elevation

It required about two- houtte tor the generator to reach

its normal operating tempe-ratu~e_ After the water in the

rheostat and generator had reached their operating temperabull

turea it was possible to begin the taking of data

The only vaPiable which was controlled wee the turbineshy

generator speed However the upper l1ut1t of safe line

current was slightly over 100 ampJilPampPes and the eireuit

breaker would open when the current reached lOS ~ere bull

Control was exercised by means ot regulating the water

level and salt 1n the water rheo tat and the res1stsnoe of

the tield rheost t~

The etfeet ot each type ot regulation on the three

variables is shown below

Volta Aaperebull Speed

Inc Dec Inc Dee~ Inc Dec

Wa~e1 Level Inc Dec~ X

X X X X

X

Salt Concentration

Inc Dec X

X X X X

X

field Resistance

Inc Dec

X X

X X

X X

32

Jlot all methods gave the ame amount ot change in a

given variable and a period of experiment and trial led to

the following scheme starting the rune with the lowest

turbine speed the water level was high with a high amount

ot salt and the field resistance was cut completely out

Aa it became necessary to increase the speed tor each

aucceasive run either cutting in t he field resistance

decreasing the salt concentration or lowering the Vater

level would produce the desired result However decreasbull

1ng the salt concentration had to be done Without a net

gain in water which led to a tluahing procedure that was

not particularly good because cold water was introduced

which required time to heat to the boiling point Cutting

1n additional field resistance was a good method but th1a

increased the amperage possibly to the point of opening

the circuit breaker Lowering the water level was aatiashy

factol1 until the level got too low causing the current

fluctuation previously mentioned Actually it turned out

that a combination of lowering the water level and cutting

field resistance in would carry the speed from ita minimum

to 1ts maximum value it the proper choice were made each

time the speed waa to be changed At the conclusion of

each aet of runs at a high speed the water level would be

low and the field resistance high

33

TURBINE

PAD AND DECK

TAILRACE

WATER SURFACamp

CONCRETE

DRAFT TU1B INSERTS

7 5( DRAFr TUBE

FLltJI ARIA

5~ DRAFT TUBE

FLOI ARSA

Figure 12 - Sketch of Draft Tube and Test Inserts

34

Figure 13 - View of Draft Tube Insert

Figure 14 - View of Draft Tube Insert

D c __ ~s_middot hedu_le of

A number was assigned to each run The fi~st number

applies to the draft tube tlow areas

1 bull 100~ flow area or 0~ oonatriction

2 - 7S tlow area or 2$ conatr1ct1on

3 SoC flow area or so~ constriction

The second number refers to the wicket gate openings

9 over gate opening

6 bull intermediate gate opening

4 bull one h lt gate opening

The third number 14entif1ea the location of the particular

1Wl in a set ot rona made at a given dratt tube tlow area

and wicket gate opening

fnua run number 1bull4bull10 would identity this as the

tenth run ot a set made at halt gate with 75 ot the draft

tube t1ow area

Rune w re made tor a g1yen dratt tube condition

Firat tor tull 41-aft tube flow area seta ot rune were

made for the overgate halt gate and intermediate gate

conditione An insert was placed in t he draft tube and

rune based on the same gate conditions were made tor the

7S~ draft tube flow area case The insert was then changed

to allow only $~ draft tube flow area

The inserts are sketched 1n Figure 12 and photographed

ln Flgurea 13 and 14 They oonaisted of circula~ segments

36

or l2 ineh plywood mount 4 on wooden legs 10 inches high

The 1nse7te were placed in position and secured by th use

ot a-clamps on the legs and the outside ot the bottom of

the draft tube The obvious disadvantage to this method

waa the neoeasity tor draining the water from the tailrace

tor a change ot 1naert The advantage vas of course the

simplicity ot design and construction

Chapter V

DATA-A Original Data

The normal data-taking crew consisted or two men

Assuming adjustments having been made to secure a certain

turbine speed (aee section on Operational Procedure) one

man would take semi-continuous speed readings with the hand

tachometer until a state or rotational equilibrium was

reached This could be only a period or two minutes up to

ten or tifteen minutes As soon as steady speed was

assured the data taking would begin The second man went

to the weighing tank Where a minimum ot three weighingamp

were made The requirement was to get three consecutive

readings such that the ditterence between tbe smallest and

largest time did not exceed 04 seconds The time to

collect a given weight ot water was then assumed to be the

arithmetic average of the three times He then went to the

hook gauge determined the hook elevation and then

recorded the data on the data sheets The first man meanshy

while had taken readings of the line voltage line current

and manometers and checked the turbine speed by multiple

readings During the length of the run all values were

38

checked to determine mean values for recording

The minimum length of one run was about five minutes

If one or more measure ants tended to drift during the run

all values wer discarded and a new run began as soon aa

qu111br1um was stabl1shedo

B -0-al_e_u_l_a_t--d Data

The h d on the tu~bine 1 defined by

($)

The maxtmwm velocity V4 was equal to about o8 tampet per

secon4 which makes it a negligible quantity when converted

into velocity head

An engineerbulla level was used to deterine the d1ffePshy

ence 1n elevation between the compound water-mercury manoshy

meter and the hook gauge Using this value the equation

for turbine bead becomes

where z4 is the hook gauge reading

The rate of flow 1 cent

w weight or water collected average time to collect

The inlet velocity v1 vas calculated by dividing the

weight rate or flow by the specific weight of water and the

)9

area ot ~e inlet pipe This was equivalent to dividing

the weight rate of flow by 490 Then the power input to the turbine is equal to

WHpin rri

10 (6)

Also

(P ~ut) Turbine

(P out) + Generator

(P lost) Generator

The power output of the generator is simplJ the

produot ot the terminal voltage and the armature (line)

curPent The power lost in the generator can be subdivided

into copper losses and stray power losses lo evaluate

these cunes based on losses of an identical generator

11leampsured by the Department ot Mechanical Engineering were

used The loss curves are reppoduced in part in Figures

15 and 16

Determination ot generator losses proceeds as tollowau

(1) From Figure 15 detem1ne the vo1tage drop in the

armature circuit using the temperatures of 1220 F and the

meaaured current

(2) The induced voltage is t~e sum of the terminal

voltage and the voltage drop 1n the armature circuit

() Entering the induced voltage and the turbine speed

into Figure 16 the stray power loss can be determined

(4) The copper lose can be evaluated from Figure 1$

using the measured current and the temperatlll-e of 1220 P

40

25 ~------~--------~--------~------~

U) -U) - 20

f-4 ~

-~ -gt 0

0

VOLTAGE DROP

~ - i -

- bullbullbull bull - -middot-middot -+ ~- + -t--+ ~ - ~ middotbull ~-~ middott- -+----- _ -4 middotmiddot- --~-+-t---r~~ ~--+t-t- - ---t-c-++~-ulf--

0 50 75 100

Figure 15 - Curves of Generator Voltage Drop and Copper Loss

41

1200

1000

800

600

800

0

0

~-

middot--~ 1shy --1 + bull l

100

I -

150 200

IIDOOED VOLTAGB (VOLTS)

Figure 16 - Curves of Generator Stray Power Loss

_ j

-bullshy -L---- shy middot -shy

250

- r

42

(5) The generator los os equal the sum of the eopp r

loss and stray power loss

~e efficiency or the turbine is taken as

etticiency u e =P out (8)Pin

~ample pound Determ1n1gg turbine Power Output

The following data are taken trom that ot Run 1-9-1

Line voltage 1040 volts Line current 870 amperesSpeed 355 revolutions per minute

The induced voltage 1a determined as follows

Line voltage 1040

Voltage drop 90 using Figure 15 with line current of 870 amperes and temperature ot 122 degrees)

Induced Toltage 1130 volta

The power output of the turbine is determined as follows

Generator output 90$0 (line voltage z line current)

Oopper loss 7 (using Figure 15 with line current of 870 amperes and temperatUe or 122 degrees)

Stray power lose 470 (using Figure 16 with speed ot 355 revolutions per miDUte and induced voltage or 1130 volts)

Turbine power output 9527 vatta

or turbine power output 1s 12z2 horsepower

43

The conversion of the calculated data to a constant

head is based on the conventional assumption of constant

efficiency regardless of turbine head For a constant head

ot 81 teet a purely arbitrary figure the tollowing relashy

tionships are ass1lJiled to be true

I ____L (9) (i)l72

(10)

For these two values the specific a peed may be combull

putedt

N t Jt VPt (11)8 243

Chapter VI

~RESULTS

A -Pr_e_ae_n_t_a_t_t_o~n g Reaultbull

Graphical presentation ot the results ot this te1t

are given as follows

Figure 17 -Turbine characteristics with 100~ dratt

tuba 1low area

Figure 18 - Turbine characteristics with 7S dratt

tube tlow area

Figure 19 bull Comparison ot power and etticiency at

over gate conditions between 100 and

75~ draft tube flow area

Figure 20 bull COZQparison of power and ettic1ency at

halt gate conditions between 100~ and

7S~ draft tube flow area

Figure 21 bull Comparison of power and etticiency at

over gate condition between 100~ and

So dratt tube tlow area

Figure 22 - Comparison in variation ot apec1t1c

speed between 100 and 75~ dratt tube

tlow area

50

45

20

-bull - 1--shy40

bull J-~ 30

~ ex

~ 20

~~ ~ -)q

I

~ - _

- -

10~ OF DRAFT TUBE FL(Jif AREA

CONSTANT HEAD OF 8l FEST10

POIER OUTPUT EFFICIENCY SPECIFIC SPEED

0 ~--------------_--------~------~------~ 400 600 800 1000 1200 1400

TURBINE SPEED (RPM)

Figure 17 - Turbine Char~cteristics with 100 Draft Tube Flow Area

50

46

-bulllle

~ 7 ~ OF DRAFt TUBE FLOW AREA

0 -~~-rl C05STAMT BEAD OF 81 mET 1J~

POIER OOTPUT ---+- ---o ~_H EFFICIDCY ~ I shy

bull ql SPECIFIC SPEKD - ~ -

bull ~ J 10 L rmiddotr- r- -

bullz- I

~~ 30 ~~--~----~~-

20 ~ ~ middot-shy

26

~~ 25

~0 ~r-----i (

Tbull -bullshy

400 600 800 1000 1200 1400

TURBINE SPEED (R PK )

Figure 18 -Turbine Characteristics with 75 Draft Tube Flow Area

47

EFFICIENCY 60

1-----shy

-~ 50~--~--~~-~middot middot middot middot r~-~----~~~~---4~-r~-~~gtt

II

POWER~ J ~ bull bull

u I

sH

40~------+-------+---- -~~--~~-~~~~

~----~rl 1 bull

I

I

0~--------------~------_------~--------

~ -OVER GATE CONDITION

COIJSTANT HEAD OF 81 FEET

0 o 10~ DRAFt TUBE

_-- _ 7~ DRAFT TUBamp FLON AREA II

10_~-----+--------r-------r----~~

400 600 800 1000 1200 1400

TURBINE SPEED (RPM)

Figure 19 middot - Comparison between 75 and 100 Draft Tube Flow Areas of Power and Efficiency at Over Gate Conshydition

48

t

bull --4 r ~- ~ middot~

70 1-----------+-~~~~~+middot ~ ~~ middot middot -~~--~~--------~~----~-+1

-~-

Atbull bull

lla-

60

amp0

40

20

10

oampOO

t _ - - ~-+- - -~-

l2 GATB COJIDITIOJJ

COJISTABT HJW) OF 81 JBET

o 0 lOQ( DRAFl TUB8 FLOI AREA

e-- - e 75 DRAFT TUBE FLOW AREA

800 1000

- r-

~

TURBIbull SPBIID (RPII)

Figure 20 - Comparison between 75 and 100 Draft Tube Flow Areas of Power and Efficiency at Half Gate Conshydition

49

60

50

-40

bull 30

IIQbull

20

10

0

400

- t - ~

EFFICIENCY

_J bull - bull bull

~ r r middot t -+ shy L -t -

OVER GAD COliDITIOI

CONSTABT BEAD OF 8l FBB

o o 10~ DRAFt TUBE FLOI ADA middot--- 5~ DRAF TUBE FLQPi AREA

600 800 1000 1200

Figure 21 -Comparison between 50~ and 100~ Draft Tube Flow Areas of Power and Efficiency at Ove~ Gate Conshydition

50

25

20

15

10

0

Figure 22

~- T -4 -t- -l --~-

t-~ I

middot --~- t ~---- _ __ _ + --

----~- --r-- --

~-=J-~-=-~ -==~ _ ~- -- ---f---1 - shy

CONSTANT HEAD OF 81 FEBT

o--o 1~ DRAFT TUBE FLltll AREA

75C DRMT TUBK FLCIJ AREAmiddot--middot-middot 600 800 1000

TURBINE SPEED (RPK)

Comparison of Specific Speeds for 75 and 100 Draft Tube Flow Areas

51

B Discussion 2 Result

Consideration of Figures 17 and 18 indicates the

overall eftioi ncy pattern or hill is significantly or

rounded for the 7$~ flow area than for the 100~ flow area

bia implies a greateP efficiency is possible at speeds

leas than or greater than design speed with an insert in

the draft tube However the muilDum efficiency is lemiddotas

Direct comparison at over gate conditions is made in

Figure 19 ~e same general trend is noted tor both the

etticiency and power curves for the 7$~ flow area case

The eurves show higher values at overspeed than do the

correaponding cWvea for the 100 flow area case It ia

not clear whether the curves have been shifted by the dratt

tube constriction or whether the curves simply bulge past

the normal curves at both overspeed and underspeed condishy

tions The power curves apparently peak near the aeme

point bullalthough maximum power is still obtained with the

normal draft tube area

For the comparison at halt gate operation shown in

Figure 20 a general improvement has apparently been made

by restriction of the draft tube flow area At every speed

the etticienoy and the power is greater for the restricted

tlow case The two ett1o1ency curves and two power curvea

are practically parallel throughout the speed range ot

teat

As the flou aroa i e decreased still farther a s1gn1

ticant change appears Reterr1ng to Figllle 211 tor the $0

flow area curves it a obvious that exit losses have

become excessive at the overgate condition because the

efficiency and power are everywhere leas than tor the case

of normal draf t tube area

Earlier it was pointed out t hat 1t the r esult s 1nd1bull

eated an increase in both power and ef tieiency- t hen it

could be assumed tha t the additional los s i ntroduced with

the draft tube insert is less than the diminished losses

due to leas shock losa and water passage losses For the

places where both the efficiency and power have been

increased we can assume that the insert has improved turshy

bine performance

For the places where the power haa been decreased

nothing can be said as to the elimination of ampbock loss

because the new lose present with the drat tube insert has

overshadowed any gains in eftecti Ve head upatJ-eam of the

insert

Near the peak of the efficiency hill howeve~ it may

be pointed out t hat shock loaa ie a minimum with a normal

draft tube and the insert merely adds an additional loss

with the resultant decrease in maximum efficiency tor the

7$~ flow area case

Perhaps the most s1gn1ticant set of eurves is shown aa

53

Figure 22 In this graph values of specific speed tor the

75 and 100~ flow area cases for both over gate and one

halt gate openings are plotted against turbine speed At

every speed and both gate openings the value ot specific

speed for th 75~ flow area case is greater than that for

the 100 t1ow area ease

Since the head is a constant for both situations this

may be interpreted in either of two ways trom equation

(11)

(1) For the same turbine apeed restriction of the

draft tube t1ow area resulted in greater turbine power

(2) For the same power amputput the turbine with 75~

draft tube flow area operated at a greater speed than did

the one with 100 flow area

Since the required diameter of a turbine varies

inversely with the speed the second interpretation could

be stated such that a smaller turbine could be used to

develop the same power output

Whether viewed trom the aspect of increased power

greater speed or reduced size the performance of the turshy

bine with reduced draft tube flow area is superior to that

with the nolmal flow are in the draft tube

The curve of specmiddotific speed versus turbine speed for

the so draft tube flow area case at over gate cond1t1ona

was not included in Figure 22 This curve lies below that

for the 100~ flow area c se at all speeds

In elaboration ot the second interpretation of Figure

22 attention is directed to the relative magnitudes ot

increased apee1f1c speed tor the two gate openings Assumbull

ing that the increase in specific speed implies a shift ot

the power curve to the right along the turbine speed scale

the power curve would be shifted more tor tbe halt gate

opening than tor the over gate opening

It thia trend could be extrapolated to the other gate

openings the tendency can be seen tor the line ot beat

speed to rotate toward the line of the operating speed as

illustrated in FigtU-e ) The advantage of this has already

been discussed

This particular turbine has a low specific speed tor a

reaction turbine Aa the rated value of apecitic apeed tor

reaction turbines increases the line ot beat speed departs

even more radically from the line of operating bullpeed It a

test similar to this were conducted on a reaction turbine

ot gleater specific speed it is pJobable t hat the rotation

ot the line of beat apeed would become more p~onounced

The scheme used in th1a teat had two obvious dr wbull

backs The first was the decision to leave all the wicket

gamiddottes installed tor all conditions ot the draft tube

These gates predominated in control of the tlow The

inserts added to the draft tube merely acted as auxiliary

55

contrGla

The aecond drawback was the choice or device to place

in the draft tube The reasons foll selection of this type

of device have been previously mentioned It is to be

anticipated that adaptation ot dratt tube flow control

would result 1n a better device for an actual turbine

installation Such apparatus might take the form of a

pneumatic bladder or a h7drau11oally operated variable

venturi section in the draft tube It is conceivable that

the gate as used in this test might be adapted also

Chapter VII

OONCLtJSIOfS

From the results of this test the following eonolubull

e1ona aa to the effect ot a variable draft tube flow area

on the performance or a r action turbine may be drawn

(1) The effect ot a variable draft tube tlow area 1a

generally favorable upon the operat1Gn ot a reaction turbull

bine because or the tendency tor the line or beat speed to

rotate toward the line ot operation This resulte in

better performance of the turbine at partbullloads

(2) he etf1o1ency eh111 tor the turbine beeomaa JDore

tlat at the top leading to a smaller max1JilWD effic1enc7

but e reater etticieney at other pointe of operation with

the insertion ot an auxiliary control ror the rate ot tlov

in the draft tube

(3) The power output of the turbine will increase at

over speed over gate conditione as well a at part gate

conditions with the proper amount or draft tube eonatr1cbull

tion or flow

(4) It is possible to eliminate at least partially

eddy type shock loss by tho introduction ot flow control

in the draft tube

BIBLIOGRAPBl

1 Addison Herbert A treatise on applied h-draul1cs New York Wiley 1954 724 Pbull

2 Allen o M and I A Winter middot Co111parative testa on experimental draft tubes Tranaact1ons ot the American ociety ot Civil Engineers 87t893bull970 1924

3 Barrows a E Water power engineering 3d ed ew York McGraw-Bill 1943 791 Pbull

Bovet G A Modern trenda in hydraulic turbine design4middot in Europe Tranaactions of the American Society ot Mechanical Engineera 75975bull993 1953bull

s Oreager William P and Joel D Justin Hydroelectrichandbook 2d ed New York Wiley 19$0 1151 Pbull

6 Daily Jamea w Hydraulic machinery Int Hunter Rouses Engineering hydraulics Hew York Wiley 19$0 p 8$8bull99

Daughertybull Robert L Bydraulie turbines ew Yorkbull7middot MoGrav-Hlll 1920 281 Pbull

8 Daugherty Robert L Inveat1gat1on of tne performance ot a reaction turbine ~anaactiona or the American Society ot Civil Engineers 7811270bull1304 1915

9 Davie L M Model and prototype testa Int Trend in hydraulle turbine practice symposium lranaactions ot the American Society ot Civil Engineers 1o63S3middot368 1941

lfJ Doland James J Hydro power engineering Hew Yorkbull Ronald 1954 209 Pbull

11 Gandy Theodore s and Elmer c Schacht Direct curshyrent motor and generator troubles operation and repair New York McGraw-Bill 1911 293 Pbull

12 Gibaon Arnold H Hydraulics and ita applications5th ed London Constable 1952 813 Pbull

58

13 Button s P Component loases in Kaplan turbinebull and The prediction of efficiency from model tests Probull coedings of the Institution or Mechanical Engineers168743-762 1954

14 Knapp R T~ Oavit t1on mechanics and its relation to the d sign or hydraulic equip ent Proceedings or tne Institution ot Mechanical Engineers 166150bull16) 1952

15 Langsdorf Alexander s Principles of direct curHnt mach1nee 5th ed New York r~cGrawbullH1ll 1940 746 Pbull

16 Lsrner Chester w Characteristica of modern hydraubull lie turbines Trans e~ions of the ~~erican Society ot Civil Engineers 66306-386 1910

17 Linsley Ray K Jr and Jobulleph B Franzin1 Eleshyments of hydraulic enginebullring New York McGrawshyBill 19$5 $82 Pbull

18 Mead Daniel w Hydraulic machinery llev York McGraw-Hill 1933 396 Pbull

19 ead Daniel w Water power engineering New York McGrawbullRill 191S 843 Pbull

20 Mockmore Charles A Part gate operation at water turbines Corvallis Oregon State College Department ot Civil Engineering 1933 11 numb leaves (Unpubshylshed typescript)

21 Mockmore Oharles A Flow characteristics in elbow dratt tubes Transactions of the Amez-ican Society ot Civil Engineers 103402middot464bull 1938

22 Moody L F Hydraulic machinery In c v Davis Handbook ot applied hydraulics New York McGrawshyHlll 1942 1082 Pbull

2) Ptau At-nold Hydrbullulie turbine handbook ld ed Milwaukee AllisbullOhalmers ManufactUIing Company 1948 70 Pbull

RheingalUI w J Recent developments in Francis turshybines Mechanical Engineering 74189-196 1952

25 Russell George E Hydraulica 5th ed New York Henry Holt 1942 466 Pbull

26 Safford A and E P- Hamilton American mixed tlow turbine and ita setting Tranampactions or the Amerieal Society of Civil Engineers 851237bull1)56 1922

27 bull Spannhake W1lhe1Dh Problems or modern pump and tur b1ne design Transactions of the American Society of Mechanical Engineers 56e22$-248 1934bull

28 Sutherlandraquo R A Better ethod or representing and middot tudying water turbine performance ~ansaetions ot thmiddote American Society of Mechanical Engineers 68t675bull 686 1946

29 Teats ot five models or draft tubes tor turbines Engineering News-Record Pbull 182-184 Aug 2 1923

30 White w M American hydztaulic turbines Mechanical Engineering S2t390bull39S 1930bull

31 White w M lhe hydraucGne rega1ner1 its developmentand appl1eat1ons 1n hydroelectric plants Meohanlobulll Engineering 43t37Sbull380 1921 middot

32 Winter I A Economic principlebull in designbull Int Trend in hydraulic urbin practice bull a ampoeiumTranaaot1ona ot the American Society ot Civil Engineerslo6332bull3S2 1941

33 Wiel1cenua G F Fluid mechan1ca or turbo-machineryNev York McGraw-Hill 1947 613 Pbull

APPENDICES

c

Appendix A

NOATIOB

A Angle between the absolute velocity vector and the tangent to the rwmer Subscripts 1 and 2 refel to entrance and exit ot the runner blade

B Angle between the relative 1elooity vector and the tangent to the rwmer Subscripta 1 and 2 refer to entrance and ezit or the runner blade

Angle between the tangent to the runner blade tip and the tangent to the runnel- Subscripts 1 and 2 reter to entrance and exit of the rt1rmer bladebull

Blade angle-gate opening conetant defined by equation (1)

e 09erall efficiency

g Gravitational acceleration assumed constant at 322 teet per second per second bull

H Turbine head detined by equation ($)

m Exit loss coeft1e1ent

Turbine speed expressed in revolutions per minute

Turbine speed under a constant head of 81 teet

specitic apeed of the turbine under a constant head ot 81 teet

p Power output in horsepower ot the tvbine

Power output of the turbine Ulder a constant head ot Sl teet

Pl- Pressure head at entrance to the tUlb1new

l1 Peripheral velocity ot the runneP Subacr1pta 1 and 2 refer to entrance and exit ot the JUnllampr blade

62

v Relative velocity reaulting trom the combination ot the absolute water velocity V and the runner periphshyeral velocity u Subscripts 1 and 2 refer to entrance and exit ot the runner blade

v] Relative velocity vector necessary to produce a tanbull gential entry into the runner blades

V Absolute water velocity Subscripts l and 2 refer to entrano and exit ot the runner blade

v2 Velocity head Subscripts 1 and 4 reter to the ~8 entrance to the turbine and the tail~ace wate~

w Unit weight ot water assumed constant at 624 pounda per cubic toot

V Weight rate ot flow in pounds per aeooncl

XX Velocity component ot ahook See Figule 2

Z Elevation head Subscripts 1 and 4 reter to entrance to the turbine and the taibace water surfacebull

Appendix B ORIGINAL DATA-Run

lfwnber

0-4-1 0-4-2 0-4-3 o-4-4 o-4-S o-4-6 0-4-7 0-4-8 0-4-9o-4-lo o-4-11 o-4-12 0-4-13

o-6-1 o-6-2 06-3 o-6-4o-6middotS o-6-6 o-6-7 o-6-8 0-6-9 o--6-lo o-6-11

Speed

rmiddot2middotbullmiddot(1)

336 38$ 451 S$9 620 669 6lt)$ 120 787 860 932

102imiddot109 bull

352 355 443middot 543middot 620 654AJs32

911 1001 1111

~essure Head rt (2)

410 410 416 426 431 43-7 439 44-9 452 467 482 soo $1 bull $

350 351 35middot7 )66 37-9 37-9 392 41 bull 3 43middot3 460 489

Elevation Bead

fjj $7 $7 $7 $7 $7 $7 51 57 5-15858 $8 58 56 56 $6565656 51 575As5a

Velocit Head

flj 07 07 07 06 06 06 06 os 05 os0404 03

09 09 oa o8 o8 os 07 07 06 o~o

Total Head rt ($)

47middot4 4A44 o 489 49-4 soo $02 $11 $14 $29 5imiddot45 2 576

41 bull $ 416 421 430 44middot3 44middot3 456 47-7 496 523551

Plow

lbtjec

326 324middot317 311 306 30029middot28 middotmiddot middot 386 275middot260 240 218

359 36~35 bull 349 345middot 339 330 318 300 273 240

Line Potential

vyqjbull 1060 1220 ~-0o 1920 2150 2000 2$60 2000 1940 18)015io11 o

1000 1100 139bull5 1760 1925 16$0 1620 1610 1540 1330 870

Line Current

amlscs 960 900 830 740 730655 70bull 0 530 660 600 5imiddot54 6 )60

982 930 860 780 ~3-545

79-5 74-5 670 560 370

P

Appendix B ORIGINAL DATA (Continued)

Run Number

Speed

Pbulltmiddotbullmiddot )

leasure Head ft(2

Elevation Head tt(J)

Velocity He-dfmiddotj

Total Bead tt($

Flow

lbstsec( )

Line Potential vo~ta( )

Line Current

amjs (sect

0bulllt)-1 0-9-2

3ll6 398

28o ~~1

$6 56

1o 10

346 347

390 365

1ooo 1190

aao 835

0-9-3 0-9-4 o-9-S

472 565 632

292 305 312

$6 s6 56

10 o9 o9

)$8 J7~o 37~7

381376 37o

1)6614oo 141o

820 ass ass o-9-6 0-9-7 0-9-8 o-9-9 0middot9-10

680 120 762 844 920

)24337346 366 390

56 $6 56 57 $7

09 os o8 oa 07

)89401 410 431454

367~ 357348 34o 322

1400 1J6o l36o 1310 1170

843 820 7957So 67~0

0-9-ll 0-912

1001 1100

41 bull 7 45-3

s 7 6~0

06 os 480 $18

299 268

980 65$

560 36~5

1-4-1 1-4-21-4-l1-4shy1-4-5 1-4-6 l-4-7 1 4-8 1-4-9 1-4-10 1middot4-ll 1-4bull12

354middot452 562 62q 674shy102 752 760- 863 932

1022 1100-

)82389 4014oa 416 41--7 423 428 44-2 45-7 486 49-2

51S757 51 5-7 5middot15zs sa $8 58 59

07 07 06 06 06 06 06 os o bull o 04 o J

446 45-)46middot4 471 ti7-9480 q86 491505 $19 548 55-4

)28 320 311 306 300 295 291 286 269 2582iimiddot21 bull

1080 14Lo 1550 153-5 1470 141-0 1385 1310 1310 1230 1120 855

970855 875 91-0 94~0 975 966 995 860 77-S 610 4fo

0 ~

Appendix B ORIGINAL DATA (Contirmed)-Run Speed Pressure Elevation Velocity Total Flow Line Line

Number Head Head Head had Potential Current rtjjmbull t~ bttec vyfs am~a12) ( ) ti fli 8

1-6-l $6 33$ $6 0bull9 400 364 1100 93 0 1-6-2 41 34laquo2 $6 oa 406 JS7middot iios a5s l-6-3 500 3~0 5bull6 os 356 1 1 o aos 41middot~1-6~4 35bull4 5-6 oa 41middot 352 16~0 82 0 5~1-6-5 5 bull 36_2 Sbull6 08 42bull6 349middot 161 ~ 0 86~0 1-6-6 622 366 $6 oe 43bull0 345middot 158 0 88~$ 16-A 649bull 37bull1 56 os 43-S 342middot 1570 895 1~- 386 57 07 46-0 192 ) 125A44 333middot 1-6-9 3) 404 5middot1 07 468 317 1620 675 1610 911 42-4 5-7 o6 48-7 298 168 0 61 0 1-6-11 999 451 56 os Sl ll 276 ~2-0 530 1-612 1115 485 58 04 54middot7 238 90 )3 0

1middot9-l 355 279 56 10 )45 385 1040 870 1-9-2 399 28J $6 10 )49 38$ 1140 86 5 l-9-3 ~ ao 291 56 ~0 35middot1 J8J_ JJ6o 815 1bull9-4 579 303 56 09 )68 375middot J4JO 830 l-9bullS 40- 313 )6 09 31middot8 370- 1460 82~0 1-9bull6 679 2) 56 09 3 bull8 364middot 1670 710 l-9-7 682 319 56 o9 384 ) 62 1460 79 5 l-9-8 724 33middot5 56 o8 399 3$6 bull 1480 76 -5 1-9-9 762 34middot3 $6 0 bull 8 407 )48 14910 13middotS 1-9-10 833middot )60 5middot7 os 42$ 339 144$ 686 1-9-ll 926 39middot1 5-7 07 455 318 1290 600 1-9-12 1000 41middot3 0-6 476 298 1115 510$ ~ 1middot9-13 1105 452 s o4 $14 2$6 710 )10

~

Appendix Bt ORIGDIAL J (Continued)

Run Speed Pressure Elevation Velocity Total Plow Line Line Number Head ltead Head jlamp$d P()ten~ibulll Current

r~~~m ft ft lbs~seo voltattj rgj twimiddot t 1 t2gt lt3 ou t ( rt

2-9-1 384 289 S 6 10 35 5 1400 1170 810 2-9-2 443middot 29$ $6 ltimiddot9 360 379middot 11(0 87$ 2-9-J 536 30bull 3 sc 09 )68 374middot 1)40 84 bull) 2-9-4 571 306 $6 09 3~1 372 120bull 0 955 2-9-5 623 316 S6 09 J l )6S UJSo 77$ 2bull9-6 669 327 S6 09 )92 )61 1240 905 2-9bull7 712 )39 56 os 40-3 351 12(0 86 bull0 2-9-8 ~5$~ J48 56 oa 412 348 1290 81 bull ) 2-9-9 04 )63 56 oa 42-7 339 12ltJO 76$ 2middotmiddot9-10 8$2 376 5middot1 07 440 33~- ~ o 710 2-9-11 955 394 5-1 o6 457 300 1100 506 2middot9-12 1000 421 $7 06 48middoti 295 1020 $18 2-9bull13 110~ 463 56 05 $2 267 620 3~0

oshy0

Appendix Gt CALCULATED DAgA

Turbine Run Generator Generator Turbine Turbine Efficiency Turbine Turbine Specit1c

Number OutputKWlt21

Loa~Jes KWlol

Outut K bull (H)

Input RP 12)

middot Percentlt13gt

Speed r~Jmiddot(

0ltput HP ~1

Speed r-m

( 6) middot

o-4-1 0middot4-2 0-4-3 0-4-4 0-4-5 0-4-6 O-qmiddot7o-4-8o-4-9 0-4bull10 0-4-11 o-4-12

1018 1o9a 1220 1)62J40214oa1J4oo 1357 1320 1164 997 718

046 o59 071 092 096 1071oo 134 104 100 109 107

14261sso 17)01948 2008 20322011 1999 19 09 1708 14-84 11o6

281279 27-7 276 215 273271 268 268 26h 258 24-5

soa 555 62$ 705 7)1145 742 74-6714645 51s 45-1

440 sos 585 720 195 sso sao 9$$ 985

1065 1135middot 1230

318 357 319 416 422 419412 39middot9 378 324 260 191

102 12bull4 148 191 21bull 3 22o 233 249 24924middot9 238 221

0-4middot13 418 104 699 228 306 1300 117 18)

o-6-1 982 045 1376 271 $08 496 376 124 o-6-2 o-6-3 G-6-4o-6-5 0-6-6

1023 1200 13 73 J415 139h

051 0middot66 oaa ()bull 96 088

14-39 1696 1958 2026 1986

276 27middot4 273 278 274

$20 61 8 717 7)0726

q95615745 8)5685

390 ll5middot3 sos soo 490

127 170 218 243 2$$

o-6-7 o-6-8 o-6-9o-6-lo

1288 1199 1032 7-45

o9o 094 09$ 096

1846 1733 1511 1128

274 276 271 260

67S 629559 43middot4

980 1085 1165 1245shy

436 )83316 21bull 7

266 276 270 239

0-6-11 322 1oo 566 2141 2JS 1350 101 177 0 --4

Appendix C CALCULATED DAlA ( Continued)-Run

Number Generator Generator

Out2ut Losaes xw LW- 12gt (lO)

Turbine Out2ut

ltPlJ

Turbine Inat lfP Jig)

Etpound1e1ency

PireentDl

Turbine Sed x-~m( 1

Turbine OutEut RPJl)

Turbine Specific

SeeedrIbullntbull

( 6)

o-9middot1 0-9-2 0-9-3 o-lt)-4 09-$ 0bull9-6 0-9-7 0-9-8 0-9-9 0-9-10 o-9-11 0-9-12

aao 994

111$ 1197 1206 1180 11)21081 982 784 5-49 2)9

0middot45oss o6$ 070 07$ 0-77 (l77 or~ o s06o 8 096

123~ 1402 1$80 1698 17bulllS 168$ 16bull18 ~middot5430 1151 a~J4 9

24middotgt24middot3248 25~25 260 260 259 267 266 26middot1 2S2

sos 577 63-7 671 676 650 621 60036J4

327 178

$) 610AlO 3$

92S 980

102$ 1070 1157middot 1230 1300 137Smiddot

44middot4 soo 523 ssomiddot 540so6 46-5 432 368 274 18~8

J46 176 21-1 255 2802s_A 28 289 288 265 231 168

1-4-1 1-4middot2 1-4-3 1-4-4 1-4-5 1-4-6 1-4-7 1-J-8 1-4~9 1-4-10 1-4-11 1-4-12

10bull48 1231 13-S6 1397 1)821375 1))8 1303 1127 953 683) 51

048 067 o7A07 0 bull79 oa1 oss o bullao osa 0lt)0 096 099

J468 1740 1921 1978 1958 19$1 1911 lSSi162 1)98 1045

603

266 264 262 262 261 2512$7 2$6 24middot7 24-3 233 217

551 660 13middot3155 75-6 7~-97 middot4 72$ 67 51middotJ 44middot9 21middot1

475 605 A4220

875middot 910 970_

1000 1090bull 1166 1243 1330

5816

44middot444middot5 430 427 412 392 329 273 188 l0-7

117 101 204 22$ 2)7245 2562sa 257251 222 179

a-C))

Appendix Ct CALCULATED -DATA ( Ocntinued)

1-6middot1 1023 o$2 14-41 26S 505 41~6 26~

54middot5 13middot3l-6-2 1201 067 1boo 625 47-9 17shy~middot41-6bull3 1296 oA9 1 middot43 26 9 700 so5 20bull 4 l-6-4 l3j5 o 0 19~09 268 71bull3 A5o 514 222 1-6-5 1) 5 o81 19(gt4 271 725 51-5 238 l-66 1398 081 198) 27-0 736 8 S13 252~-middot l-6j 1405 083 199i 211 733 885 $middot06 2$9 l-6 13middot9~ 103 2amp 0 279 71 8 985~ 467 ~-69 1228 1 bull 02 17-SS 270 661 109$ 407 ~3~ l-6bull10 1025 100 lSll 26i 573 1175middot 27~S32middot~l-ampu 153 1-00 llft3 26 444 1270 22 24bull8 1bull6-12 294 100 52a 231 22 3 1360 95 172

1-9bull1 904 048 1275 2J4Z $28 S4$ 459 1$2 1-92 98$ oss 13-92 24middot4 57-0 6JO 49bull1 176 1-9middot3 1110 066 1$76 24middot9 63middot4 I2o 536 21-7 l--9-4 1187 072 1685 251 66$ 5 $$ bull 0 261 1middot9-5 llltJ7 1710 25middot4 67-3 93$ 536 28~20-671middot9-6 1186 o 8 1708 25-7 67) 980 $15 2691-9- 1161 oBo 1660 2$middot3 6$6 990 508 29-1 l~- ll-32 oB) 16sect0 2$8 632 1030 471 291 1-9bull9 109$ oa5 2$7 614 1075 29S~middot 0 4imiddot41-9-10 9~91 oas 262 S$1 1150~ 3 o 292 1-9-11 o9o u57 12JiO 21gt 26-77middot74

-45 26sect ~middot91-912 $69 091 sas 25 middot3 1)0$ 196 2J-8 1-9-1) 220 098 426 2)9 178 1390middot 84 16 6

0 0

Appendx C CALCULATED DATA (Continued)

Turbine Run Generator Generator lurbine Turbine Eft1e1eney Turbine lurbine Spee1f1c

Number Output Losses Outit Input Speed Output SPed middot k_-V KW R _ H_bull_P Percent r Thm HP rpm_ (9) tlo) 11) middot (12 _) (lJI ( ) (1$ (14)

2-9-1 9--46 055 1)62 258 528 580 164 2-9-2 1024 056 248 58 4 665 4 9 191iimiddot48 4~middot0 2-9-3 1132 067 05 2$0 641 795 52q 237 2-9-4 1148 065 1027 2$1 -~8 845 525 252 2-9-5 11 77 oso 16-83 253 6 910~ 522 270 2-9 6 1122 071 1600 251 622 960 47-5 2722-9-A 1092 015 1562 257 608 1010 445 2z12bull9- 1052 079 1514 261 580 1060 41middot7 2 2 2middot9-9 986 o82 ]429 26) 542 1105 372 277 2-9-10 915 086 1340 268 500 1160 334 27-6 2-9-11 638 087 972 254 )81 1270~ 229 250 2-9-12 )28 090 828 259 )19 1295 179 226 2-9-13 192 094 383 2$ 6 150 1370 7 3 152

-3 0

Page 15: The Effect of A Variable Draft Tube Flow Area on the

examples of flew in conventional pipes elbows and convergbull

1ng passages If this comparison may be made it could be

assumed that the losses encountered in these locations

would be proportional to vn ~ value ot N is normally2g

aesU111ed to be 2

he losses encountered between the wicket gates an4

the turbine runner and exit lossos are special cases which

will be discussed separately

B Shock toes_

The flow betwe n the wicket gat outlet and the runner

blade entrance is or particular 1nt rest because no direct

comparison vith common flow situations is obvious

Conaider the vector diagram (7 Pbull 7576) in Figure 2

The veetoo v1 is the absolute entering velocity of the

water and is fixed in magnitude and direction by the setbull

ting or the wicket gates The vector l11 1e the peripheztal

velocity of the runnel which tol any given turbine 1e

dependent only upon the turbine rotational speed The

combination of these two vectors ylelda the third vector

v1 which is the relative entering velocity ot the water

nere is only one setting ot the wicket gates for a

given turbine a peed that will produce an angle B1 which

coincides with the blade angle B1bull At other gate settings

the vector v1 will rotate and change in magnitude in such a

9

t ehion that B1 will beoome either greater or 1 sa than B1bull Th1 give rise to tbe phenomenon term d shock loasft

If B1 1a greater than B1 the relative ent ring veloebull

ityt v1 will have a compon~nt opposing the forward motion

of the runner The shock loss could be typified bullbull that

occasioned by direct impact or the water 0n the blade- If

E1 is lese than a] the vector l will overshoot the blade

and the flow will tend to eddy around the forward portion

or the blade tip

The shock loss can then be either due to impact or

eddying flow Since the area norm 1 to the radius at outlampt

of the w1eket gftee is essentially equ 1 to the area normnl

to the rad1u~ at the inlet to the turbine runner the combull

ponents ot vl and vl perpendicular to ul will b approxishy

mately equal This leads to the conclusion that xxbull ~epresenting the shock vector 1 parallel to Ulbull

For either the impact or eddy case the trigonometric

law of $1nee leads tot

XX

bull ul - sin (Bi-Al) vl eln Bi

It it 1a assumed that the energy lost in the shock 1a

the Telocity head ot the shock component XX then

10

VELOCITY VECTOR DIAGIWI

TYPES OF SHOCK LOSS

xbull X

IMPACT BDDJ

XX 1a Teloc1t7 caponent ot shock

Figure 2 - ~bine Runner Vector Diagram$ and Shock Loss Diagrams

11

2 shock loss (XX gt2g

C =sin (BimiddotAl)Let (1)sin Bi

(UlmiddotCV1)2Then shock loabull (2)- 2g

For a given gate opening C ia a constant ranging

from about 14 to 10 For a well designed wheel it is to middot

be expected that C would be approximately equal to U1V1

at rated conditions ie at point of maximum efficiency

This point will occur in the neighborhood of 3~ to 78

gate opening for moat turbines For overgate conditions

the angle A1 becomes larger so the value of C would

decrease For gate openings below rated conditions t he

angle A1 decreases and C would decrease One could expect

a fairly uniform decrease in t he value of C as the gate is

closed from t he overgate position

The velocity v1 is approximately constant for any

turbine speed since the area and rate of flow both decrease

fairly uniformly However for a given gate opening the

velocity V1 will decrease with increased turbine speed

From the foregoing comments and equation (2) the

following trends can be established

(1) For constant turbine speed the shook loss curve

will be close to parabolic in shape concave upward and

have its maximum near t he point of complete gate closure

--

12

and its minimum near the rated gate position

(2) For conatant gate opening the shook loss curve

will approximate a symmetrical parabola with its vertex

the point of minimum loas located at the rated condition

of operation (7 Pbull 79)

c Exit Loas

It can be seen from Figure 2 that the exit loss from

the turbine would be v222g if no draft tube were present

The addition of a draft tube permits the gradual reduction

of velocity by an increase in cross sectional area between

the exit of the runner and the exit from the draft tube

The exit loss and the frictional loss encountered in

the draft tube may be placed together in the expression

m va2 (3)Exit Loss ~---2g

For the ideal case of no friction in the draft tube

m is equal to the square of the ratio of the area at exit

from the runner to the area at exit from the draft tube

In an actual turbine installation however friction

will change the value of m (7 p 84-85) to somewhere

between that for the ideal case and a maximum ot 10

In the interest of maintaining a minimum exit loss

the turbine should be designed and operated so the velocity

V2 will be minimum This will occur when the discharge

13

vector is at right angles to the tangent to the runnerbull

ie the angle A2 1e ninety degree bull It ia to be expected

that this condition will be tultilled near the design con~

d1t1ons ot the ~bine

Current design praetiee 1 to have a small component

ot v2 in th$ direction of turbine rotation at rated condibull

tion$ ltS p 938)

For a constant turbine speed the d1seharg or exit

loss is ess nti lly a constant

For a constant gate opening the exit lo s curve is

aptrroximately a symmetrical pa~abola with ita vert x the

point or minimum loss located at a slightly lowe~ speed

th n the turbine rated speed (7 Pbull 79)

Chapter III

PROPOSAL OP ALlERMAlE MFTBO 0 CO TROL-A lz ~ Location 2 Control

Thua tar only practice and theoretical aspects appemiddotrbull

taining to present day turbinea have been d1acuaaed It

haa been presented that control over the ~bine ia ezerbull

oiaed b y manipulation of the wicket gatea located 11101led1bull

ately preceding the runner These gate - upon rotation

modify both the magn1tu4e and the direction ot the entering

velocit7 Moreover it has be n shown that a simultaneous

change in these two variables leads to inefficient operabull

tion by the introduction of shock loss he farther the

point of operation a from the rated conditione the more

aerioua ia the ahock loss encountered

Any attempt to better turbine pertorance at other

than rated conditione and tbne flatten the top ot the

etticieney hill8 must concentrate upon the lessening ot

the ahock loaa It 1a a aumed that 1 provement in the

scroll case gates and runners would lequ1re sueh pertecbull

tion 1n machine work and metal$ as to be prohibitively

expensive

It ie surmised that any move to elblinate eYen parbull

tially the shock loss would require separate control ovel

l$

the flow and gate exit angle Since it is improbable that

d1~ect1on could be controlled at any location other than

where the gatea are situated in current turbines it will

be assumed that guide vanes will be necessary regardlesa or the method used to control the rate of flow

The primary purpose ot th se guide vanes 1s that or control over the direction ot the incoming water They

should be free to rotate in much the same manner as ordibull

nary wicket gates in order to exercise control over th

turbine speed

If the rate ot tlov is to be controlled elsewhere it

must be modified either in the penstock or the draft tube

Devices that could be used are standard valves gates

variable orifices variable venturi sections and associated

flow regulating schemes

Alauming it were decided to locate such a device upbull

stream of the turbine it would be necessary to allow disbull

tance tor the flow picture to become reestablished prior to

entry to the turbine A contused flow making transit of

the turbine passages would only contribute additional loesbull

ea Such a distance allowance would be perbapa 20 to So

diameters (2$ Pbull 119-123) In large penstocka th1a would

repreaent a considerable distance Which from the viewbull

points ot convenience and control would be undesirable

Attempts to ascertain the effect or additional tlov

16

reduc ion at the wicket gatctsmiddot wae ade 1n the lfadraulioe middot

Laboratory of Oregon St middot te College in 1933 (20) Three

d1tterent thode ot reducins the tlow were t~ied

(l) Locking in the cloeed position pairs or wicket

gatea located opposite to eaeh o~er on the -periphery ot

the wheel

(2) Locking adjacent gates in an open position by

inserting blocks of wood between them and

()) Suocess1vely looking adjacent gates in the closed

position

The results indicated a arked reduction in both power

and efficiency when compared to the curves tor normal gate

operation However it was demonstrated that it was poae1bull

ble to ahitt the power and tfieiency curve ill relation to

turbine apeed lbis important feature will be diacussed

later

ihe main conclusion of the investigation was that conbull

trol by the conyent1onal wick t gates was auper1or to other

methode egtt control exercised at the gates the aelvebullbull

It would app$ar that the bebullt location tor flow conshy

trol would be in the draft tube since none of the objecbull

tiona prev1ously mentioned wou~d eziat there

As bas been stated previously the sole object or the

17

18

turbine is to produce power as etfic1ently as possible

The equation tor the power output of a turbine () Pbull 227)

PaWHe HP (4)55o bull bull Assuming the head 1a constant and a g te located in

the draft tube decreases bhe rate ot flow the power eu

only be increased if the etticiency increases

The ettective head Gn the turbine 1s conventionally

d r1ned as the difference between the auma ot the elevashy

tion head pressure head and velocity head at the entrance

to the turbine casing and the tailrace ($ Pbull 872)

lt ie recognized that the theoretical treatment ot

shock loss as given is highly approximate and serves only

to dictate certain trenda For example the area at xit

rom the wicket g tea CfUl be measuPed with some exactness

but there exists no guarantee that the wateP particles will

complet-ely fill the apace oz- will exit at the establiahed

g te angle The same can be said of the exit trom the

runner blades AssUIlptiona were implied which would indishy

cate that all water particles passing a given croea section

ampH traveling at the same velocity in the same direction

the e alone are autt1c1ent to show 11m1tationa in a theoretbull

1eal approach to the problem

Assume a turbine with ordinary wicket gates tor oonbull

trol compared gainst the same turbine with a gate in the

18

draft tttbe tor supplampment1ng control or the rate ot rlow

Let it also be assumed that the two turbines are opershy

ating at the same point It 1s desirable to predict relabull

tive performance of the two turbines 1 this point of

operation is such that edd7 s hook loss ot reasonable proshy

portions is present in the fir t turbine

~ tull erteot of the shock loss will be exper1 need

by- the fir t turbine

lhe second turbine will derive certain advantages 11

the gate in the draft tube is adjusted to reduce the tlov

1n the proper amount Since they vary a the square ot

the veloo1t7bull the lossabull in the aeroll case wiomiddotket gate

and runner passages will decx-ease aetet-r1ng to Figure 2 1

it can be seen that a decreased velocity v1 w-ill reduce the

eddy shock losa

The ent loss in the dJtaft tube of the second turbine

will be the sum ot the tr1ct1onal loss and the velocity

head at ex1t The velocity head dissipated will be greater

due to the closing action or the gate but the reduoed

t~ictional loss which ia a tunction ot the rate of tlow1

will partially balance this

It 1a entirely possible that the net reduction in

losses in the second turbine will lead to a greater ettibull

oiency and more power output than 4eYeloped by the first

turbine

19

In Figure 3 the plot ot power output against turbine

speed for Curv A~ represents the typical family of curvea

tor a reaction turbine Th b st sp ed is the locus ot

points connecting maximum eft1oiency at each gate opening

The operating speed is the coZUJtant turbine apeed which

passes through the point ot maximum efC1ciencr of the turbull

bine The plot of turbine efficiency against power output

for Curve A is also ahown

It the turbine with flow regulation in the dratt tube

oan demonstrate superior power and efficiency at part loads

the effect would be the same as a shifting or the power

curves toward the condition shown fop Curve B 11 Thisbull

illustrates th ultimate case of the uperpoait1on of best

and operating speeds It will be noted that the pet-form~

of the turbine ot Ourve Bu 1a better than that of CUrve

A at part loads because of ita ability to sustain a relabull

tively high etticienoy ovel a Wider range of power output

o Reguireaegts tort Test Velitication

It is desired to deterra1ne the effect on the turbine

performance b) the addition of a gate in the dratt tube

Th step in the teit will bet

(1 To determine the power output and efficiency ot

the turbine tor wicket gate settings above and below rated

conditione for a wide range ot speed

20

CURVEAbull

TURBINE SPSBD TURBID SPEKD

POIBR OOTPOl

Figure 3 - Turbine Performance Curves

21

22

(2 peat (l) with the gate installed in the drat

tube

(3) middot Converting middot all data to a constant head compare the

powere and effioiencies at the same wicket gate setting and

turbin speed tor the two cbullses

If the ddition or the gate indicates an improvement

in power output and efficiency and the powe~ curve shifts

to the right along the turbine apeed scale the advantage

ot draft tube con~ol of the flow will hav been demonshy

strated

Chapter IV

A E9J11pment

ih turbine used in this test is lJ 5 1nch Pelton

reaction turbine with a rated output ot 30 horsepower under

a head of 56 feet at a speed ot 720 reYolutiona per minute

Views of this turbine are hovn in Figures S and 6 The

turbine is installed on a concrete pad located over an open

channel in the Hydraulics Laboratory at Oregon State Colshy

lege The date of manufacture of this turbine was 1915

The water was delivered to the turbine from a sump

reservoir by two pumps operating 1n parallel Each pump 1a

an 8 inch Pelton double suction centrifugal pump witb a

rating of l$00 gallons per minute at a head ot 75 teet with

a speed ot 1175 revolutions per minute Tbe inlet tlange

ot tne turbine is $pprox1mately 18 feet above the center

line of the pump

A direct current generator was coupled to the turbine

to receive tne power d veloped as shown in Figures 4 and 7 The generator is a Spr gue Electrodynamometer rated at SS horsepower with a speed range of 7$0 to l$00 revolut1one

per minute The classification is type LO 26A 2)0 volta

Figure 5 - View of Test Turbine

Figure 6 ~ View of Test Turbine

and 149 amperes lbe generator ti ld was aepar tely

excited using direct current from a motor g n r tor ampt

(l$ p 4~8)

The power output of the generator waa dissipated in

the water rheostat (3 p 488-489) shown in Figures 9 and

10 The galvanized tank contain d water ot variable d pth

on an electrode ot cast iron m aauring 1bull x 1 x 1

In the initial installation of the turbine it was

intended that the power output should be measured with a

Prony brak bull For th purpoa68 or this teat it was decided

that the brake was too instable and the generator was

substituted The platform for raising the generator the

nee asary two teet for alignment was built out of available

material In this case heavy laminated wood blocks reiashy

torced with other timbers were used and bolted through the

concrete deck (11 Pbull 36-$7)

Due to the light concrete deck the lack ot mas in

the platform and the slight misalignment in the flexible

coupling ao e vibration waa encountered It seemed to

ncr aae linearly to a maximum at the speed of bout 750

revolutions per minute Above this speed no vibPation was

noticeable The vibration waa not se~ere and does not

appear to have materially affected the test results

26

B Intrumentat1on ~ eaeur1ng Devices

The pressure head at inlet to the turbine vaa meaave4

bymeane ot two )6 inch waterbullmeroury manometerbull connected

in series as shown in Figure 8

The terminal voltage ot the generator vas meaeured by

a laboratory voltDleter with a range to )00 yolta and callbull

brated to within 15 Yolta

The armature current bull and hence the line current was

measured by a laboratory ammeter with a range to 150 amperea

and callbrated to w1 thin o 7S amperes

Tae rate ot tlow was established by weight and time

meaeurementa The weighing ank has a capacity ot 121 000

poundsJ the weight belng indicated by Toledo direct reading

scales Timing was done with a hand atop watch with clivibull

aion ot 02 second

he ~ater level in the tailrace was dete~1ned by a

hook gauge lhie was read to the nearest 001 toot

The turbine and generator speeds were eaaured by a

hand tachometer The technique of almost cont1nuoua readbull

ings of the speed gave an error ot no more than 5 revolubull

tiona per minute

c Operational Procedure

Atter the water level in the aump was checked to

insure an adequate auppl7 the puapa were primed and

27

Figure 7 - Test Generator and Plattorm

Figure middot8- Instrument Board and Field Rheostat

28

started After venting they were valved for operation 1n

parallel

The motor generator set was started to supply the

field current and the circuit breaker was closed Water

wa added to the water rheostat to the level shown in

Figure 10 ~ field current wae minimized by cutting in

all the f ield resistance in the field rheostat of Figure 8

The l2 inch gate valve shown in Figures 5 and 6 waa

slowly opened and the turbine and generator brought up to

speed The 12 inch gat valve and turbine were vented and

the pumps were checked to insure neither had lost ita prime

lhe water rheostat offers very steady load 1f the

water level is essentially constant and the water temperabull

ture 1a fixed () p 488~89) In order to maintain this

constant temperature it was decided not to circulate the

water in the rheostat but rather to allow the water to

boil thua achieving the desired result A standing wave

was set up on the face ot the electrode by the boiling

action but a atable load was eatablished except at very

low water leYels where th11 agitation led to fluctuationa

in the line current

After putting the turbine and generator on the line

maximum power was dissipated in the rheostat by redueing

the turbine speed to between oSO and Soo revolutions per

minute Salt vas added to the rheoetat wat r to increasemiddot

29

Figure 9 - View of Water Rheostat

Figure 10 - View of Water Rheostat

Separate Field ExcitationFrom Motor-Generator set Compound Water-Mercury

---shy

re Manometer

I Q)

~ 0

~

Book Gauge

Open Channel

I

Slap Reservoir

Figure 11 - Wat~r Flow Diagram and Electrical Layout

31

waiting pe~iod ot perhaps an h~ followed

while the boiling point or the water wbulls reacbe4 During

this ti+ne the manometer was vented end eheoked electrical

measur1ng 1nstlUments were connected end the hook gauge was

adjusted tor elevation

It required about two- houtte tor the generator to reach

its normal operating tempe-ratu~e_ After the water in the

rheostat and generator had reached their operating temperabull

turea it was possible to begin the taking of data

The only vaPiable which was controlled wee the turbineshy

generator speed However the upper l1ut1t of safe line

current was slightly over 100 ampJilPampPes and the eireuit

breaker would open when the current reached lOS ~ere bull

Control was exercised by means ot regulating the water

level and salt 1n the water rheo tat and the res1stsnoe of

the tield rheost t~

The etfeet ot each type ot regulation on the three

variables is shown below

Volta Aaperebull Speed

Inc Dec Inc Dee~ Inc Dec

Wa~e1 Level Inc Dec~ X

X X X X

X

Salt Concentration

Inc Dec X

X X X X

X

field Resistance

Inc Dec

X X

X X

X X

32

Jlot all methods gave the ame amount ot change in a

given variable and a period of experiment and trial led to

the following scheme starting the rune with the lowest

turbine speed the water level was high with a high amount

ot salt and the field resistance was cut completely out

Aa it became necessary to increase the speed tor each

aucceasive run either cutting in t he field resistance

decreasing the salt concentration or lowering the Vater

level would produce the desired result However decreasbull

1ng the salt concentration had to be done Without a net

gain in water which led to a tluahing procedure that was

not particularly good because cold water was introduced

which required time to heat to the boiling point Cutting

1n additional field resistance was a good method but th1a

increased the amperage possibly to the point of opening

the circuit breaker Lowering the water level was aatiashy

factol1 until the level got too low causing the current

fluctuation previously mentioned Actually it turned out

that a combination of lowering the water level and cutting

field resistance in would carry the speed from ita minimum

to 1ts maximum value it the proper choice were made each

time the speed waa to be changed At the conclusion of

each aet of runs at a high speed the water level would be

low and the field resistance high

33

TURBINE

PAD AND DECK

TAILRACE

WATER SURFACamp

CONCRETE

DRAFT TU1B INSERTS

7 5( DRAFr TUBE

FLltJI ARIA

5~ DRAFT TUBE

FLOI ARSA

Figure 12 - Sketch of Draft Tube and Test Inserts

34

Figure 13 - View of Draft Tube Insert

Figure 14 - View of Draft Tube Insert

D c __ ~s_middot hedu_le of

A number was assigned to each run The fi~st number

applies to the draft tube tlow areas

1 bull 100~ flow area or 0~ oonatriction

2 - 7S tlow area or 2$ conatr1ct1on

3 SoC flow area or so~ constriction

The second number refers to the wicket gate openings

9 over gate opening

6 bull intermediate gate opening

4 bull one h lt gate opening

The third number 14entif1ea the location of the particular

1Wl in a set ot rona made at a given dratt tube tlow area

and wicket gate opening

fnua run number 1bull4bull10 would identity this as the

tenth run ot a set made at halt gate with 75 ot the draft

tube t1ow area

Rune w re made tor a g1yen dratt tube condition

Firat tor tull 41-aft tube flow area seta ot rune were

made for the overgate halt gate and intermediate gate

conditione An insert was placed in t he draft tube and

rune based on the same gate conditions were made tor the

7S~ draft tube flow area case The insert was then changed

to allow only $~ draft tube flow area

The inserts are sketched 1n Figure 12 and photographed

ln Flgurea 13 and 14 They oonaisted of circula~ segments

36

or l2 ineh plywood mount 4 on wooden legs 10 inches high

The 1nse7te were placed in position and secured by th use

ot a-clamps on the legs and the outside ot the bottom of

the draft tube The obvious disadvantage to this method

waa the neoeasity tor draining the water from the tailrace

tor a change ot 1naert The advantage vas of course the

simplicity ot design and construction

Chapter V

DATA-A Original Data

The normal data-taking crew consisted or two men

Assuming adjustments having been made to secure a certain

turbine speed (aee section on Operational Procedure) one

man would take semi-continuous speed readings with the hand

tachometer until a state or rotational equilibrium was

reached This could be only a period or two minutes up to

ten or tifteen minutes As soon as steady speed was

assured the data taking would begin The second man went

to the weighing tank Where a minimum ot three weighingamp

were made The requirement was to get three consecutive

readings such that the ditterence between tbe smallest and

largest time did not exceed 04 seconds The time to

collect a given weight ot water was then assumed to be the

arithmetic average of the three times He then went to the

hook gauge determined the hook elevation and then

recorded the data on the data sheets The first man meanshy

while had taken readings of the line voltage line current

and manometers and checked the turbine speed by multiple

readings During the length of the run all values were

38

checked to determine mean values for recording

The minimum length of one run was about five minutes

If one or more measure ants tended to drift during the run

all values wer discarded and a new run began as soon aa

qu111br1um was stabl1shedo

B -0-al_e_u_l_a_t--d Data

The h d on the tu~bine 1 defined by

($)

The maxtmwm velocity V4 was equal to about o8 tampet per

secon4 which makes it a negligible quantity when converted

into velocity head

An engineerbulla level was used to deterine the d1ffePshy

ence 1n elevation between the compound water-mercury manoshy

meter and the hook gauge Using this value the equation

for turbine bead becomes

where z4 is the hook gauge reading

The rate of flow 1 cent

w weight or water collected average time to collect

The inlet velocity v1 vas calculated by dividing the

weight rate or flow by the specific weight of water and the

)9

area ot ~e inlet pipe This was equivalent to dividing

the weight rate of flow by 490 Then the power input to the turbine is equal to

WHpin rri

10 (6)

Also

(P ~ut) Turbine

(P out) + Generator

(P lost) Generator

The power output of the generator is simplJ the

produot ot the terminal voltage and the armature (line)

curPent The power lost in the generator can be subdivided

into copper losses and stray power losses lo evaluate

these cunes based on losses of an identical generator

11leampsured by the Department ot Mechanical Engineering were

used The loss curves are reppoduced in part in Figures

15 and 16

Determination ot generator losses proceeds as tollowau

(1) From Figure 15 detem1ne the vo1tage drop in the

armature circuit using the temperatures of 1220 F and the

meaaured current

(2) The induced voltage is t~e sum of the terminal

voltage and the voltage drop 1n the armature circuit

() Entering the induced voltage and the turbine speed

into Figure 16 the stray power loss can be determined

(4) The copper lose can be evaluated from Figure 1$

using the measured current and the temperatlll-e of 1220 P

40

25 ~------~--------~--------~------~

U) -U) - 20

f-4 ~

-~ -gt 0

0

VOLTAGE DROP

~ - i -

- bullbullbull bull - -middot-middot -+ ~- + -t--+ ~ - ~ middotbull ~-~ middott- -+----- _ -4 middotmiddot- --~-+-t---r~~ ~--+t-t- - ---t-c-++~-ulf--

0 50 75 100

Figure 15 - Curves of Generator Voltage Drop and Copper Loss

41

1200

1000

800

600

800

0

0

~-

middot--~ 1shy --1 + bull l

100

I -

150 200

IIDOOED VOLTAGB (VOLTS)

Figure 16 - Curves of Generator Stray Power Loss

_ j

-bullshy -L---- shy middot -shy

250

- r

42

(5) The generator los os equal the sum of the eopp r

loss and stray power loss

~e efficiency or the turbine is taken as

etticiency u e =P out (8)Pin

~ample pound Determ1n1gg turbine Power Output

The following data are taken trom that ot Run 1-9-1

Line voltage 1040 volts Line current 870 amperesSpeed 355 revolutions per minute

The induced voltage 1a determined as follows

Line voltage 1040

Voltage drop 90 using Figure 15 with line current of 870 amperes and temperature ot 122 degrees)

Induced Toltage 1130 volta

The power output of the turbine is determined as follows

Generator output 90$0 (line voltage z line current)

Oopper loss 7 (using Figure 15 with line current of 870 amperes and temperatUe or 122 degrees)

Stray power lose 470 (using Figure 16 with speed ot 355 revolutions per miDUte and induced voltage or 1130 volts)

Turbine power output 9527 vatta

or turbine power output 1s 12z2 horsepower

43

The conversion of the calculated data to a constant

head is based on the conventional assumption of constant

efficiency regardless of turbine head For a constant head

ot 81 teet a purely arbitrary figure the tollowing relashy

tionships are ass1lJiled to be true

I ____L (9) (i)l72

(10)

For these two values the specific a peed may be combull

putedt

N t Jt VPt (11)8 243

Chapter VI

~RESULTS

A -Pr_e_ae_n_t_a_t_t_o~n g Reaultbull

Graphical presentation ot the results ot this te1t

are given as follows

Figure 17 -Turbine characteristics with 100~ dratt

tuba 1low area

Figure 18 - Turbine characteristics with 7S dratt

tube tlow area

Figure 19 bull Comparison ot power and etticiency at

over gate conditions between 100 and

75~ draft tube flow area

Figure 20 bull COZQparison of power and ettic1ency at

halt gate conditions between 100~ and

7S~ draft tube flow area

Figure 21 bull Comparison of power and etticiency at

over gate condition between 100~ and

So dratt tube tlow area

Figure 22 - Comparison in variation ot apec1t1c

speed between 100 and 75~ dratt tube

tlow area

50

45

20

-bull - 1--shy40

bull J-~ 30

~ ex

~ 20

~~ ~ -)q

I

~ - _

- -

10~ OF DRAFT TUBE FL(Jif AREA

CONSTANT HEAD OF 8l FEST10

POIER OUTPUT EFFICIENCY SPECIFIC SPEED

0 ~--------------_--------~------~------~ 400 600 800 1000 1200 1400

TURBINE SPEED (RPM)

Figure 17 - Turbine Char~cteristics with 100 Draft Tube Flow Area

50

46

-bulllle

~ 7 ~ OF DRAFt TUBE FLOW AREA

0 -~~-rl C05STAMT BEAD OF 81 mET 1J~

POIER OOTPUT ---+- ---o ~_H EFFICIDCY ~ I shy

bull ql SPECIFIC SPEKD - ~ -

bull ~ J 10 L rmiddotr- r- -

bullz- I

~~ 30 ~~--~----~~-

20 ~ ~ middot-shy

26

~~ 25

~0 ~r-----i (

Tbull -bullshy

400 600 800 1000 1200 1400

TURBINE SPEED (R PK )

Figure 18 -Turbine Characteristics with 75 Draft Tube Flow Area

47

EFFICIENCY 60

1-----shy

-~ 50~--~--~~-~middot middot middot middot r~-~----~~~~---4~-r~-~~gtt

II

POWER~ J ~ bull bull

u I

sH

40~------+-------+---- -~~--~~-~~~~

~----~rl 1 bull

I

I

0~--------------~------_------~--------

~ -OVER GATE CONDITION

COIJSTANT HEAD OF 81 FEET

0 o 10~ DRAFt TUBE

_-- _ 7~ DRAFT TUBamp FLON AREA II

10_~-----+--------r-------r----~~

400 600 800 1000 1200 1400

TURBINE SPEED (RPM)

Figure 19 middot - Comparison between 75 and 100 Draft Tube Flow Areas of Power and Efficiency at Over Gate Conshydition

48

t

bull --4 r ~- ~ middot~

70 1-----------+-~~~~~+middot ~ ~~ middot middot -~~--~~--------~~----~-+1

-~-

Atbull bull

lla-

60

amp0

40

20

10

oampOO

t _ - - ~-+- - -~-

l2 GATB COJIDITIOJJ

COJISTABT HJW) OF 81 JBET

o 0 lOQ( DRAFl TUB8 FLOI AREA

e-- - e 75 DRAFT TUBE FLOW AREA

800 1000

- r-

~

TURBIbull SPBIID (RPII)

Figure 20 - Comparison between 75 and 100 Draft Tube Flow Areas of Power and Efficiency at Half Gate Conshydition

49

60

50

-40

bull 30

IIQbull

20

10

0

400

- t - ~

EFFICIENCY

_J bull - bull bull

~ r r middot t -+ shy L -t -

OVER GAD COliDITIOI

CONSTABT BEAD OF 8l FBB

o o 10~ DRAFt TUBE FLOI ADA middot--- 5~ DRAF TUBE FLQPi AREA

600 800 1000 1200

Figure 21 -Comparison between 50~ and 100~ Draft Tube Flow Areas of Power and Efficiency at Ove~ Gate Conshydition

50

25

20

15

10

0

Figure 22

~- T -4 -t- -l --~-

t-~ I

middot --~- t ~---- _ __ _ + --

----~- --r-- --

~-=J-~-=-~ -==~ _ ~- -- ---f---1 - shy

CONSTANT HEAD OF 81 FEBT

o--o 1~ DRAFT TUBE FLltll AREA

75C DRMT TUBK FLCIJ AREAmiddot--middot-middot 600 800 1000

TURBINE SPEED (RPK)

Comparison of Specific Speeds for 75 and 100 Draft Tube Flow Areas

51

B Discussion 2 Result

Consideration of Figures 17 and 18 indicates the

overall eftioi ncy pattern or hill is significantly or

rounded for the 7$~ flow area than for the 100~ flow area

bia implies a greateP efficiency is possible at speeds

leas than or greater than design speed with an insert in

the draft tube However the muilDum efficiency is lemiddotas

Direct comparison at over gate conditions is made in

Figure 19 ~e same general trend is noted tor both the

etticiency and power curves for the 7$~ flow area case

The eurves show higher values at overspeed than do the

correaponding cWvea for the 100 flow area case It ia

not clear whether the curves have been shifted by the dratt

tube constriction or whether the curves simply bulge past

the normal curves at both overspeed and underspeed condishy

tions The power curves apparently peak near the aeme

point bullalthough maximum power is still obtained with the

normal draft tube area

For the comparison at halt gate operation shown in

Figure 20 a general improvement has apparently been made

by restriction of the draft tube flow area At every speed

the etticienoy and the power is greater for the restricted

tlow case The two ett1o1ency curves and two power curvea

are practically parallel throughout the speed range ot

teat

As the flou aroa i e decreased still farther a s1gn1

ticant change appears Reterr1ng to Figllle 211 tor the $0

flow area curves it a obvious that exit losses have

become excessive at the overgate condition because the

efficiency and power are everywhere leas than tor the case

of normal draf t tube area

Earlier it was pointed out t hat 1t the r esult s 1nd1bull

eated an increase in both power and ef tieiency- t hen it

could be assumed tha t the additional los s i ntroduced with

the draft tube insert is less than the diminished losses

due to leas shock losa and water passage losses For the

places where both the efficiency and power have been

increased we can assume that the insert has improved turshy

bine performance

For the places where the power haa been decreased

nothing can be said as to the elimination of ampbock loss

because the new lose present with the drat tube insert has

overshadowed any gains in eftecti Ve head upatJ-eam of the

insert

Near the peak of the efficiency hill howeve~ it may

be pointed out t hat shock loaa ie a minimum with a normal

draft tube and the insert merely adds an additional loss

with the resultant decrease in maximum efficiency tor the

7$~ flow area case

Perhaps the most s1gn1ticant set of eurves is shown aa

53

Figure 22 In this graph values of specific speed tor the

75 and 100~ flow area cases for both over gate and one

halt gate openings are plotted against turbine speed At

every speed and both gate openings the value ot specific

speed for th 75~ flow area case is greater than that for

the 100 t1ow area ease

Since the head is a constant for both situations this

may be interpreted in either of two ways trom equation

(11)

(1) For the same turbine apeed restriction of the

draft tube t1ow area resulted in greater turbine power

(2) For the same power amputput the turbine with 75~

draft tube flow area operated at a greater speed than did

the one with 100 flow area

Since the required diameter of a turbine varies

inversely with the speed the second interpretation could

be stated such that a smaller turbine could be used to

develop the same power output

Whether viewed trom the aspect of increased power

greater speed or reduced size the performance of the turshy

bine with reduced draft tube flow area is superior to that

with the nolmal flow are in the draft tube

The curve of specmiddotific speed versus turbine speed for

the so draft tube flow area case at over gate cond1t1ona

was not included in Figure 22 This curve lies below that

for the 100~ flow area c se at all speeds

In elaboration ot the second interpretation of Figure

22 attention is directed to the relative magnitudes ot

increased apee1f1c speed tor the two gate openings Assumbull

ing that the increase in specific speed implies a shift ot

the power curve to the right along the turbine speed scale

the power curve would be shifted more tor tbe halt gate

opening than tor the over gate opening

It thia trend could be extrapolated to the other gate

openings the tendency can be seen tor the line ot beat

speed to rotate toward the line of the operating speed as

illustrated in FigtU-e ) The advantage of this has already

been discussed

This particular turbine has a low specific speed tor a

reaction turbine Aa the rated value of apecitic apeed tor

reaction turbines increases the line ot beat speed departs

even more radically from the line of operating bullpeed It a

test similar to this were conducted on a reaction turbine

ot gleater specific speed it is pJobable t hat the rotation

ot the line of beat apeed would become more p~onounced

The scheme used in th1a teat had two obvious dr wbull

backs The first was the decision to leave all the wicket

gamiddottes installed tor all conditions ot the draft tube

These gates predominated in control of the tlow The

inserts added to the draft tube merely acted as auxiliary

55

contrGla

The aecond drawback was the choice or device to place

in the draft tube The reasons foll selection of this type

of device have been previously mentioned It is to be

anticipated that adaptation ot dratt tube flow control

would result 1n a better device for an actual turbine

installation Such apparatus might take the form of a

pneumatic bladder or a h7drau11oally operated variable

venturi section in the draft tube It is conceivable that

the gate as used in this test might be adapted also

Chapter VII

OONCLtJSIOfS

From the results of this test the following eonolubull

e1ona aa to the effect ot a variable draft tube flow area

on the performance or a r action turbine may be drawn

(1) The effect ot a variable draft tube tlow area 1a

generally favorable upon the operat1Gn ot a reaction turbull

bine because or the tendency tor the line or beat speed to

rotate toward the line ot operation This resulte in

better performance of the turbine at partbullloads

(2) he etf1o1ency eh111 tor the turbine beeomaa JDore

tlat at the top leading to a smaller max1JilWD effic1enc7

but e reater etticieney at other pointe of operation with

the insertion ot an auxiliary control ror the rate ot tlov

in the draft tube

(3) The power output of the turbine will increase at

over speed over gate conditione as well a at part gate

conditions with the proper amount or draft tube eonatr1cbull

tion or flow

(4) It is possible to eliminate at least partially

eddy type shock loss by tho introduction ot flow control

in the draft tube

BIBLIOGRAPBl

1 Addison Herbert A treatise on applied h-draul1cs New York Wiley 1954 724 Pbull

2 Allen o M and I A Winter middot Co111parative testa on experimental draft tubes Tranaact1ons ot the American ociety ot Civil Engineers 87t893bull970 1924

3 Barrows a E Water power engineering 3d ed ew York McGraw-Bill 1943 791 Pbull

Bovet G A Modern trenda in hydraulic turbine design4middot in Europe Tranaactions of the American Society ot Mechanical Engineera 75975bull993 1953bull

s Oreager William P and Joel D Justin Hydroelectrichandbook 2d ed New York Wiley 19$0 1151 Pbull

6 Daily Jamea w Hydraulic machinery Int Hunter Rouses Engineering hydraulics Hew York Wiley 19$0 p 8$8bull99

Daughertybull Robert L Bydraulie turbines ew Yorkbull7middot MoGrav-Hlll 1920 281 Pbull

8 Daugherty Robert L Inveat1gat1on of tne performance ot a reaction turbine ~anaactiona or the American Society ot Civil Engineers 7811270bull1304 1915

9 Davie L M Model and prototype testa Int Trend in hydraulle turbine practice symposium lranaactions ot the American Society ot Civil Engineers 1o63S3middot368 1941

lfJ Doland James J Hydro power engineering Hew Yorkbull Ronald 1954 209 Pbull

11 Gandy Theodore s and Elmer c Schacht Direct curshyrent motor and generator troubles operation and repair New York McGraw-Bill 1911 293 Pbull

12 Gibaon Arnold H Hydraulics and ita applications5th ed London Constable 1952 813 Pbull

58

13 Button s P Component loases in Kaplan turbinebull and The prediction of efficiency from model tests Probull coedings of the Institution or Mechanical Engineers168743-762 1954

14 Knapp R T~ Oavit t1on mechanics and its relation to the d sign or hydraulic equip ent Proceedings or tne Institution ot Mechanical Engineers 166150bull16) 1952

15 Langsdorf Alexander s Principles of direct curHnt mach1nee 5th ed New York r~cGrawbullH1ll 1940 746 Pbull

16 Lsrner Chester w Characteristica of modern hydraubull lie turbines Trans e~ions of the ~~erican Society ot Civil Engineers 66306-386 1910

17 Linsley Ray K Jr and Jobulleph B Franzin1 Eleshyments of hydraulic enginebullring New York McGrawshyBill 19$5 $82 Pbull

18 Mead Daniel w Hydraulic machinery llev York McGraw-Hill 1933 396 Pbull

19 ead Daniel w Water power engineering New York McGrawbullRill 191S 843 Pbull

20 Mockmore Charles A Part gate operation at water turbines Corvallis Oregon State College Department ot Civil Engineering 1933 11 numb leaves (Unpubshylshed typescript)

21 Mockmore Oharles A Flow characteristics in elbow dratt tubes Transactions of the Amez-ican Society ot Civil Engineers 103402middot464bull 1938

22 Moody L F Hydraulic machinery In c v Davis Handbook ot applied hydraulics New York McGrawshyHlll 1942 1082 Pbull

2) Ptau At-nold Hydrbullulie turbine handbook ld ed Milwaukee AllisbullOhalmers ManufactUIing Company 1948 70 Pbull

RheingalUI w J Recent developments in Francis turshybines Mechanical Engineering 74189-196 1952

25 Russell George E Hydraulica 5th ed New York Henry Holt 1942 466 Pbull

26 Safford A and E P- Hamilton American mixed tlow turbine and ita setting Tranampactions or the Amerieal Society of Civil Engineers 851237bull1)56 1922

27 bull Spannhake W1lhe1Dh Problems or modern pump and tur b1ne design Transactions of the American Society of Mechanical Engineers 56e22$-248 1934bull

28 Sutherlandraquo R A Better ethod or representing and middot tudying water turbine performance ~ansaetions ot thmiddote American Society of Mechanical Engineers 68t675bull 686 1946

29 Teats ot five models or draft tubes tor turbines Engineering News-Record Pbull 182-184 Aug 2 1923

30 White w M American hydztaulic turbines Mechanical Engineering S2t390bull39S 1930bull

31 White w M lhe hydraucGne rega1ner1 its developmentand appl1eat1ons 1n hydroelectric plants Meohanlobulll Engineering 43t37Sbull380 1921 middot

32 Winter I A Economic principlebull in designbull Int Trend in hydraulic urbin practice bull a ampoeiumTranaaot1ona ot the American Society ot Civil Engineerslo6332bull3S2 1941

33 Wiel1cenua G F Fluid mechan1ca or turbo-machineryNev York McGraw-Hill 1947 613 Pbull

APPENDICES

c

Appendix A

NOATIOB

A Angle between the absolute velocity vector and the tangent to the rwmer Subscripts 1 and 2 refel to entrance and exit ot the runner blade

B Angle between the relative 1elooity vector and the tangent to the rwmer Subscripta 1 and 2 refer to entrance and ezit or the runner blade

Angle between the tangent to the runner blade tip and the tangent to the runnel- Subscripts 1 and 2 reter to entrance and exit of the rt1rmer bladebull

Blade angle-gate opening conetant defined by equation (1)

e 09erall efficiency

g Gravitational acceleration assumed constant at 322 teet per second per second bull

H Turbine head detined by equation ($)

m Exit loss coeft1e1ent

Turbine speed expressed in revolutions per minute

Turbine speed under a constant head of 81 teet

specitic apeed of the turbine under a constant head ot 81 teet

p Power output in horsepower ot the tvbine

Power output of the turbine Ulder a constant head ot Sl teet

Pl- Pressure head at entrance to the tUlb1new

l1 Peripheral velocity ot the runneP Subacr1pta 1 and 2 refer to entrance and exit ot the JUnllampr blade

62

v Relative velocity reaulting trom the combination ot the absolute water velocity V and the runner periphshyeral velocity u Subscripts 1 and 2 refer to entrance and exit ot the runner blade

v] Relative velocity vector necessary to produce a tanbull gential entry into the runner blades

V Absolute water velocity Subscripts l and 2 refer to entrano and exit ot the runner blade

v2 Velocity head Subscripts 1 and 4 reter to the ~8 entrance to the turbine and the tail~ace wate~

w Unit weight ot water assumed constant at 624 pounda per cubic toot

V Weight rate ot flow in pounds per aeooncl

XX Velocity component ot ahook See Figule 2

Z Elevation head Subscripts 1 and 4 reter to entrance to the turbine and the taibace water surfacebull

Appendix B ORIGINAL DATA-Run

lfwnber

0-4-1 0-4-2 0-4-3 o-4-4 o-4-S o-4-6 0-4-7 0-4-8 0-4-9o-4-lo o-4-11 o-4-12 0-4-13

o-6-1 o-6-2 06-3 o-6-4o-6middotS o-6-6 o-6-7 o-6-8 0-6-9 o--6-lo o-6-11

Speed

rmiddot2middotbullmiddot(1)

336 38$ 451 S$9 620 669 6lt)$ 120 787 860 932

102imiddot109 bull

352 355 443middot 543middot 620 654AJs32

911 1001 1111

~essure Head rt (2)

410 410 416 426 431 43-7 439 44-9 452 467 482 soo $1 bull $

350 351 35middot7 )66 37-9 37-9 392 41 bull 3 43middot3 460 489

Elevation Bead

fjj $7 $7 $7 $7 $7 $7 51 57 5-15858 $8 58 56 56 $6565656 51 575As5a

Velocit Head

flj 07 07 07 06 06 06 06 os 05 os0404 03

09 09 oa o8 o8 os 07 07 06 o~o

Total Head rt ($)

47middot4 4A44 o 489 49-4 soo $02 $11 $14 $29 5imiddot45 2 576

41 bull $ 416 421 430 44middot3 44middot3 456 47-7 496 523551

Plow

lbtjec

326 324middot317 311 306 30029middot28 middotmiddot middot 386 275middot260 240 218

359 36~35 bull 349 345middot 339 330 318 300 273 240

Line Potential

vyqjbull 1060 1220 ~-0o 1920 2150 2000 2$60 2000 1940 18)015io11 o

1000 1100 139bull5 1760 1925 16$0 1620 1610 1540 1330 870

Line Current

amlscs 960 900 830 740 730655 70bull 0 530 660 600 5imiddot54 6 )60

982 930 860 780 ~3-545

79-5 74-5 670 560 370

P

Appendix B ORIGINAL DATA (Continued)

Run Number

Speed

Pbulltmiddotbullmiddot )

leasure Head ft(2

Elevation Head tt(J)

Velocity He-dfmiddotj

Total Bead tt($

Flow

lbstsec( )

Line Potential vo~ta( )

Line Current

amjs (sect

0bulllt)-1 0-9-2

3ll6 398

28o ~~1

$6 56

1o 10

346 347

390 365

1ooo 1190

aao 835

0-9-3 0-9-4 o-9-S

472 565 632

292 305 312

$6 s6 56

10 o9 o9

)$8 J7~o 37~7

381376 37o

1)6614oo 141o

820 ass ass o-9-6 0-9-7 0-9-8 o-9-9 0middot9-10

680 120 762 844 920

)24337346 366 390

56 $6 56 57 $7

09 os o8 oa 07

)89401 410 431454

367~ 357348 34o 322

1400 1J6o l36o 1310 1170

843 820 7957So 67~0

0-9-ll 0-912

1001 1100

41 bull 7 45-3

s 7 6~0

06 os 480 $18

299 268

980 65$

560 36~5

1-4-1 1-4-21-4-l1-4shy1-4-5 1-4-6 l-4-7 1 4-8 1-4-9 1-4-10 1middot4-ll 1-4bull12

354middot452 562 62q 674shy102 752 760- 863 932

1022 1100-

)82389 4014oa 416 41--7 423 428 44-2 45-7 486 49-2

51S757 51 5-7 5middot15zs sa $8 58 59

07 07 06 06 06 06 06 os o bull o 04 o J

446 45-)46middot4 471 ti7-9480 q86 491505 $19 548 55-4

)28 320 311 306 300 295 291 286 269 2582iimiddot21 bull

1080 14Lo 1550 153-5 1470 141-0 1385 1310 1310 1230 1120 855

970855 875 91-0 94~0 975 966 995 860 77-S 610 4fo

0 ~

Appendix B ORIGINAL DATA (Contirmed)-Run Speed Pressure Elevation Velocity Total Flow Line Line

Number Head Head Head had Potential Current rtjjmbull t~ bttec vyfs am~a12) ( ) ti fli 8

1-6-l $6 33$ $6 0bull9 400 364 1100 93 0 1-6-2 41 34laquo2 $6 oa 406 JS7middot iios a5s l-6-3 500 3~0 5bull6 os 356 1 1 o aos 41middot~1-6~4 35bull4 5-6 oa 41middot 352 16~0 82 0 5~1-6-5 5 bull 36_2 Sbull6 08 42bull6 349middot 161 ~ 0 86~0 1-6-6 622 366 $6 oe 43bull0 345middot 158 0 88~$ 16-A 649bull 37bull1 56 os 43-S 342middot 1570 895 1~- 386 57 07 46-0 192 ) 125A44 333middot 1-6-9 3) 404 5middot1 07 468 317 1620 675 1610 911 42-4 5-7 o6 48-7 298 168 0 61 0 1-6-11 999 451 56 os Sl ll 276 ~2-0 530 1-612 1115 485 58 04 54middot7 238 90 )3 0

1middot9-l 355 279 56 10 )45 385 1040 870 1-9-2 399 28J $6 10 )49 38$ 1140 86 5 l-9-3 ~ ao 291 56 ~0 35middot1 J8J_ JJ6o 815 1bull9-4 579 303 56 09 )68 375middot J4JO 830 l-9bullS 40- 313 )6 09 31middot8 370- 1460 82~0 1-9bull6 679 2) 56 09 3 bull8 364middot 1670 710 l-9-7 682 319 56 o9 384 ) 62 1460 79 5 l-9-8 724 33middot5 56 o8 399 3$6 bull 1480 76 -5 1-9-9 762 34middot3 $6 0 bull 8 407 )48 14910 13middotS 1-9-10 833middot )60 5middot7 os 42$ 339 144$ 686 1-9-ll 926 39middot1 5-7 07 455 318 1290 600 1-9-12 1000 41middot3 0-6 476 298 1115 510$ ~ 1middot9-13 1105 452 s o4 $14 2$6 710 )10

~

Appendix Bt ORIGDIAL J (Continued)

Run Speed Pressure Elevation Velocity Total Plow Line Line Number Head ltead Head jlamp$d P()ten~ibulll Current

r~~~m ft ft lbs~seo voltattj rgj twimiddot t 1 t2gt lt3 ou t ( rt

2-9-1 384 289 S 6 10 35 5 1400 1170 810 2-9-2 443middot 29$ $6 ltimiddot9 360 379middot 11(0 87$ 2-9-J 536 30bull 3 sc 09 )68 374middot 1)40 84 bull) 2-9-4 571 306 $6 09 3~1 372 120bull 0 955 2-9-5 623 316 S6 09 J l )6S UJSo 77$ 2bull9-6 669 327 S6 09 )92 )61 1240 905 2-9bull7 712 )39 56 os 40-3 351 12(0 86 bull0 2-9-8 ~5$~ J48 56 oa 412 348 1290 81 bull ) 2-9-9 04 )63 56 oa 42-7 339 12ltJO 76$ 2middotmiddot9-10 8$2 376 5middot1 07 440 33~- ~ o 710 2-9-11 955 394 5-1 o6 457 300 1100 506 2middot9-12 1000 421 $7 06 48middoti 295 1020 $18 2-9bull13 110~ 463 56 05 $2 267 620 3~0

oshy0

Appendix Gt CALCULATED DAgA

Turbine Run Generator Generator Turbine Turbine Efficiency Turbine Turbine Specit1c

Number OutputKWlt21

Loa~Jes KWlol

Outut K bull (H)

Input RP 12)

middot Percentlt13gt

Speed r~Jmiddot(

0ltput HP ~1

Speed r-m

( 6) middot

o-4-1 0middot4-2 0-4-3 0-4-4 0-4-5 0-4-6 O-qmiddot7o-4-8o-4-9 0-4bull10 0-4-11 o-4-12

1018 1o9a 1220 1)62J40214oa1J4oo 1357 1320 1164 997 718

046 o59 071 092 096 1071oo 134 104 100 109 107

14261sso 17)01948 2008 20322011 1999 19 09 1708 14-84 11o6

281279 27-7 276 215 273271 268 268 26h 258 24-5

soa 555 62$ 705 7)1145 742 74-6714645 51s 45-1

440 sos 585 720 195 sso sao 9$$ 985

1065 1135middot 1230

318 357 319 416 422 419412 39middot9 378 324 260 191

102 12bull4 148 191 21bull 3 22o 233 249 24924middot9 238 221

0-4middot13 418 104 699 228 306 1300 117 18)

o-6-1 982 045 1376 271 $08 496 376 124 o-6-2 o-6-3 G-6-4o-6-5 0-6-6

1023 1200 13 73 J415 139h

051 0middot66 oaa ()bull 96 088

14-39 1696 1958 2026 1986

276 27middot4 273 278 274

$20 61 8 717 7)0726

q95615745 8)5685

390 ll5middot3 sos soo 490

127 170 218 243 2$$

o-6-7 o-6-8 o-6-9o-6-lo

1288 1199 1032 7-45

o9o 094 09$ 096

1846 1733 1511 1128

274 276 271 260

67S 629559 43middot4

980 1085 1165 1245shy

436 )83316 21bull 7

266 276 270 239

0-6-11 322 1oo 566 2141 2JS 1350 101 177 0 --4

Appendix C CALCULATED DAlA ( Continued)-Run

Number Generator Generator

Out2ut Losaes xw LW- 12gt (lO)

Turbine Out2ut

ltPlJ

Turbine Inat lfP Jig)

Etpound1e1ency

PireentDl

Turbine Sed x-~m( 1

Turbine OutEut RPJl)

Turbine Specific

SeeedrIbullntbull

( 6)

o-9middot1 0-9-2 0-9-3 o-lt)-4 09-$ 0bull9-6 0-9-7 0-9-8 0-9-9 0-9-10 o-9-11 0-9-12

aao 994

111$ 1197 1206 1180 11)21081 982 784 5-49 2)9

0middot45oss o6$ 070 07$ 0-77 (l77 or~ o s06o 8 096

123~ 1402 1$80 1698 17bulllS 168$ 16bull18 ~middot5430 1151 a~J4 9

24middotgt24middot3248 25~25 260 260 259 267 266 26middot1 2S2

sos 577 63-7 671 676 650 621 60036J4

327 178

$) 610AlO 3$

92S 980

102$ 1070 1157middot 1230 1300 137Smiddot

44middot4 soo 523 ssomiddot 540so6 46-5 432 368 274 18~8

J46 176 21-1 255 2802s_A 28 289 288 265 231 168

1-4-1 1-4middot2 1-4-3 1-4-4 1-4-5 1-4-6 1-4-7 1-J-8 1-4~9 1-4-10 1-4-11 1-4-12

10bull48 1231 13-S6 1397 1)821375 1))8 1303 1127 953 683) 51

048 067 o7A07 0 bull79 oa1 oss o bullao osa 0lt)0 096 099

J468 1740 1921 1978 1958 19$1 1911 lSSi162 1)98 1045

603

266 264 262 262 261 2512$7 2$6 24middot7 24-3 233 217

551 660 13middot3155 75-6 7~-97 middot4 72$ 67 51middotJ 44middot9 21middot1

475 605 A4220

875middot 910 970_

1000 1090bull 1166 1243 1330

5816

44middot444middot5 430 427 412 392 329 273 188 l0-7

117 101 204 22$ 2)7245 2562sa 257251 222 179

a-C))

Appendix Ct CALCULATED -DATA ( Ocntinued)

1-6middot1 1023 o$2 14-41 26S 505 41~6 26~

54middot5 13middot3l-6-2 1201 067 1boo 625 47-9 17shy~middot41-6bull3 1296 oA9 1 middot43 26 9 700 so5 20bull 4 l-6-4 l3j5 o 0 19~09 268 71bull3 A5o 514 222 1-6-5 1) 5 o81 19(gt4 271 725 51-5 238 l-66 1398 081 198) 27-0 736 8 S13 252~-middot l-6j 1405 083 199i 211 733 885 $middot06 2$9 l-6 13middot9~ 103 2amp 0 279 71 8 985~ 467 ~-69 1228 1 bull 02 17-SS 270 661 109$ 407 ~3~ l-6bull10 1025 100 lSll 26i 573 1175middot 27~S32middot~l-ampu 153 1-00 llft3 26 444 1270 22 24bull8 1bull6-12 294 100 52a 231 22 3 1360 95 172

1-9bull1 904 048 1275 2J4Z $28 S4$ 459 1$2 1-92 98$ oss 13-92 24middot4 57-0 6JO 49bull1 176 1-9middot3 1110 066 1$76 24middot9 63middot4 I2o 536 21-7 l--9-4 1187 072 1685 251 66$ 5 $$ bull 0 261 1middot9-5 llltJ7 1710 25middot4 67-3 93$ 536 28~20-671middot9-6 1186 o 8 1708 25-7 67) 980 $15 2691-9- 1161 oBo 1660 2$middot3 6$6 990 508 29-1 l~- ll-32 oB) 16sect0 2$8 632 1030 471 291 1-9bull9 109$ oa5 2$7 614 1075 29S~middot 0 4imiddot41-9-10 9~91 oas 262 S$1 1150~ 3 o 292 1-9-11 o9o u57 12JiO 21gt 26-77middot74

-45 26sect ~middot91-912 $69 091 sas 25 middot3 1)0$ 196 2J-8 1-9-1) 220 098 426 2)9 178 1390middot 84 16 6

0 0

Appendx C CALCULATED DATA (Continued)

Turbine Run Generator Generator lurbine Turbine Eft1e1eney Turbine lurbine Spee1f1c

Number Output Losses Outit Input Speed Output SPed middot k_-V KW R _ H_bull_P Percent r Thm HP rpm_ (9) tlo) 11) middot (12 _) (lJI ( ) (1$ (14)

2-9-1 9--46 055 1)62 258 528 580 164 2-9-2 1024 056 248 58 4 665 4 9 191iimiddot48 4~middot0 2-9-3 1132 067 05 2$0 641 795 52q 237 2-9-4 1148 065 1027 2$1 -~8 845 525 252 2-9-5 11 77 oso 16-83 253 6 910~ 522 270 2-9 6 1122 071 1600 251 622 960 47-5 2722-9-A 1092 015 1562 257 608 1010 445 2z12bull9- 1052 079 1514 261 580 1060 41middot7 2 2 2middot9-9 986 o82 ]429 26) 542 1105 372 277 2-9-10 915 086 1340 268 500 1160 334 27-6 2-9-11 638 087 972 254 )81 1270~ 229 250 2-9-12 )28 090 828 259 )19 1295 179 226 2-9-13 192 094 383 2$ 6 150 1370 7 3 152

-3 0

Page 16: The Effect of A Variable Draft Tube Flow Area on the

9

t ehion that B1 will beoome either greater or 1 sa than B1bull Th1 give rise to tbe phenomenon term d shock loasft

If B1 1a greater than B1 the relative ent ring veloebull

ityt v1 will have a compon~nt opposing the forward motion

of the runner The shock loss could be typified bullbull that

occasioned by direct impact or the water 0n the blade- If

E1 is lese than a] the vector l will overshoot the blade

and the flow will tend to eddy around the forward portion

or the blade tip

The shock loss can then be either due to impact or

eddying flow Since the area norm 1 to the radius at outlampt

of the w1eket gftee is essentially equ 1 to the area normnl

to the rad1u~ at the inlet to the turbine runner the combull

ponents ot vl and vl perpendicular to ul will b approxishy

mately equal This leads to the conclusion that xxbull ~epresenting the shock vector 1 parallel to Ulbull

For either the impact or eddy case the trigonometric

law of $1nee leads tot

XX

bull ul - sin (Bi-Al) vl eln Bi

It it 1a assumed that the energy lost in the shock 1a

the Telocity head ot the shock component XX then

10

VELOCITY VECTOR DIAGIWI

TYPES OF SHOCK LOSS

xbull X

IMPACT BDDJ

XX 1a Teloc1t7 caponent ot shock

Figure 2 - ~bine Runner Vector Diagram$ and Shock Loss Diagrams

11

2 shock loss (XX gt2g

C =sin (BimiddotAl)Let (1)sin Bi

(UlmiddotCV1)2Then shock loabull (2)- 2g

For a given gate opening C ia a constant ranging

from about 14 to 10 For a well designed wheel it is to middot

be expected that C would be approximately equal to U1V1

at rated conditions ie at point of maximum efficiency

This point will occur in the neighborhood of 3~ to 78

gate opening for moat turbines For overgate conditions

the angle A1 becomes larger so the value of C would

decrease For gate openings below rated conditions t he

angle A1 decreases and C would decrease One could expect

a fairly uniform decrease in t he value of C as the gate is

closed from t he overgate position

The velocity v1 is approximately constant for any

turbine speed since the area and rate of flow both decrease

fairly uniformly However for a given gate opening the

velocity V1 will decrease with increased turbine speed

From the foregoing comments and equation (2) the

following trends can be established

(1) For constant turbine speed the shook loss curve

will be close to parabolic in shape concave upward and

have its maximum near t he point of complete gate closure

--

12

and its minimum near the rated gate position

(2) For conatant gate opening the shook loss curve

will approximate a symmetrical parabola with its vertex

the point of minimum loas located at the rated condition

of operation (7 Pbull 79)

c Exit Loas

It can be seen from Figure 2 that the exit loss from

the turbine would be v222g if no draft tube were present

The addition of a draft tube permits the gradual reduction

of velocity by an increase in cross sectional area between

the exit of the runner and the exit from the draft tube

The exit loss and the frictional loss encountered in

the draft tube may be placed together in the expression

m va2 (3)Exit Loss ~---2g

For the ideal case of no friction in the draft tube

m is equal to the square of the ratio of the area at exit

from the runner to the area at exit from the draft tube

In an actual turbine installation however friction

will change the value of m (7 p 84-85) to somewhere

between that for the ideal case and a maximum ot 10

In the interest of maintaining a minimum exit loss

the turbine should be designed and operated so the velocity

V2 will be minimum This will occur when the discharge

13

vector is at right angles to the tangent to the runnerbull

ie the angle A2 1e ninety degree bull It ia to be expected

that this condition will be tultilled near the design con~

d1t1ons ot the ~bine

Current design praetiee 1 to have a small component

ot v2 in th$ direction of turbine rotation at rated condibull

tion$ ltS p 938)

For a constant turbine speed the d1seharg or exit

loss is ess nti lly a constant

For a constant gate opening the exit lo s curve is

aptrroximately a symmetrical pa~abola with ita vert x the

point or minimum loss located at a slightly lowe~ speed

th n the turbine rated speed (7 Pbull 79)

Chapter III

PROPOSAL OP ALlERMAlE MFTBO 0 CO TROL-A lz ~ Location 2 Control

Thua tar only practice and theoretical aspects appemiddotrbull

taining to present day turbinea have been d1acuaaed It

haa been presented that control over the ~bine ia ezerbull

oiaed b y manipulation of the wicket gatea located 11101led1bull

ately preceding the runner These gate - upon rotation

modify both the magn1tu4e and the direction ot the entering

velocit7 Moreover it has be n shown that a simultaneous

change in these two variables leads to inefficient operabull

tion by the introduction of shock loss he farther the

point of operation a from the rated conditione the more

aerioua ia the ahock loss encountered

Any attempt to better turbine pertorance at other

than rated conditione and tbne flatten the top ot the

etticieney hill8 must concentrate upon the lessening ot

the ahock loaa It 1a a aumed that 1 provement in the

scroll case gates and runners would lequ1re sueh pertecbull

tion 1n machine work and metal$ as to be prohibitively

expensive

It ie surmised that any move to elblinate eYen parbull

tially the shock loss would require separate control ovel

l$

the flow and gate exit angle Since it is improbable that

d1~ect1on could be controlled at any location other than

where the gatea are situated in current turbines it will

be assumed that guide vanes will be necessary regardlesa or the method used to control the rate of flow

The primary purpose ot th se guide vanes 1s that or control over the direction ot the incoming water They

should be free to rotate in much the same manner as ordibull

nary wicket gates in order to exercise control over th

turbine speed

If the rate ot tlov is to be controlled elsewhere it

must be modified either in the penstock or the draft tube

Devices that could be used are standard valves gates

variable orifices variable venturi sections and associated

flow regulating schemes

Alauming it were decided to locate such a device upbull

stream of the turbine it would be necessary to allow disbull

tance tor the flow picture to become reestablished prior to

entry to the turbine A contused flow making transit of

the turbine passages would only contribute additional loesbull

ea Such a distance allowance would be perbapa 20 to So

diameters (2$ Pbull 119-123) In large penstocka th1a would

repreaent a considerable distance Which from the viewbull

points ot convenience and control would be undesirable

Attempts to ascertain the effect or additional tlov

16

reduc ion at the wicket gatctsmiddot wae ade 1n the lfadraulioe middot

Laboratory of Oregon St middot te College in 1933 (20) Three

d1tterent thode ot reducins the tlow were t~ied

(l) Locking in the cloeed position pairs or wicket

gatea located opposite to eaeh o~er on the -periphery ot

the wheel

(2) Locking adjacent gates in an open position by

inserting blocks of wood between them and

()) Suocess1vely looking adjacent gates in the closed

position

The results indicated a arked reduction in both power

and efficiency when compared to the curves tor normal gate

operation However it was demonstrated that it was poae1bull

ble to ahitt the power and tfieiency curve ill relation to

turbine apeed lbis important feature will be diacussed

later

ihe main conclusion of the investigation was that conbull

trol by the conyent1onal wick t gates was auper1or to other

methode egtt control exercised at the gates the aelvebullbull

It would app$ar that the bebullt location tor flow conshy

trol would be in the draft tube since none of the objecbull

tiona prev1ously mentioned wou~d eziat there

As bas been stated previously the sole object or the

17

18

turbine is to produce power as etfic1ently as possible

The equation tor the power output of a turbine () Pbull 227)

PaWHe HP (4)55o bull bull Assuming the head 1a constant and a g te located in

the draft tube decreases bhe rate ot flow the power eu

only be increased if the etticiency increases

The ettective head Gn the turbine 1s conventionally

d r1ned as the difference between the auma ot the elevashy

tion head pressure head and velocity head at the entrance

to the turbine casing and the tailrace ($ Pbull 872)

lt ie recognized that the theoretical treatment ot

shock loss as given is highly approximate and serves only

to dictate certain trenda For example the area at xit

rom the wicket g tea CfUl be measuPed with some exactness

but there exists no guarantee that the wateP particles will

complet-ely fill the apace oz- will exit at the establiahed

g te angle The same can be said of the exit trom the

runner blades AssUIlptiona were implied which would indishy

cate that all water particles passing a given croea section

ampH traveling at the same velocity in the same direction

the e alone are autt1c1ent to show 11m1tationa in a theoretbull

1eal approach to the problem

Assume a turbine with ordinary wicket gates tor oonbull

trol compared gainst the same turbine with a gate in the

18

draft tttbe tor supplampment1ng control or the rate ot rlow

Let it also be assumed that the two turbines are opershy

ating at the same point It 1s desirable to predict relabull

tive performance of the two turbines 1 this point of

operation is such that edd7 s hook loss ot reasonable proshy

portions is present in the fir t turbine

~ tull erteot of the shock loss will be exper1 need

by- the fir t turbine

lhe second turbine will derive certain advantages 11

the gate in the draft tube is adjusted to reduce the tlov

1n the proper amount Since they vary a the square ot

the veloo1t7bull the lossabull in the aeroll case wiomiddotket gate

and runner passages will decx-ease aetet-r1ng to Figure 2 1

it can be seen that a decreased velocity v1 w-ill reduce the

eddy shock losa

The ent loss in the dJtaft tube of the second turbine

will be the sum ot the tr1ct1onal loss and the velocity

head at ex1t The velocity head dissipated will be greater

due to the closing action or the gate but the reduoed

t~ictional loss which ia a tunction ot the rate of tlow1

will partially balance this

It 1a entirely possible that the net reduction in

losses in the second turbine will lead to a greater ettibull

oiency and more power output than 4eYeloped by the first

turbine

19

In Figure 3 the plot ot power output against turbine

speed for Curv A~ represents the typical family of curvea

tor a reaction turbine Th b st sp ed is the locus ot

points connecting maximum eft1oiency at each gate opening

The operating speed is the coZUJtant turbine apeed which

passes through the point ot maximum efC1ciencr of the turbull

bine The plot of turbine efficiency against power output

for Curve A is also ahown

It the turbine with flow regulation in the dratt tube

oan demonstrate superior power and efficiency at part loads

the effect would be the same as a shifting or the power

curves toward the condition shown fop Curve B 11 Thisbull

illustrates th ultimate case of the uperpoait1on of best

and operating speeds It will be noted that the pet-form~

of the turbine ot Ourve Bu 1a better than that of CUrve

A at part loads because of ita ability to sustain a relabull

tively high etticienoy ovel a Wider range of power output

o Reguireaegts tort Test Velitication

It is desired to deterra1ne the effect on the turbine

performance b) the addition of a gate in the dratt tube

Th step in the teit will bet

(1 To determine the power output and efficiency ot

the turbine tor wicket gate settings above and below rated

conditione for a wide range ot speed

20

CURVEAbull

TURBINE SPSBD TURBID SPEKD

POIBR OOTPOl

Figure 3 - Turbine Performance Curves

21

22

(2 peat (l) with the gate installed in the drat

tube

(3) middot Converting middot all data to a constant head compare the

powere and effioiencies at the same wicket gate setting and

turbin speed tor the two cbullses

If the ddition or the gate indicates an improvement

in power output and efficiency and the powe~ curve shifts

to the right along the turbine apeed scale the advantage

ot draft tube con~ol of the flow will hav been demonshy

strated

Chapter IV

A E9J11pment

ih turbine used in this test is lJ 5 1nch Pelton

reaction turbine with a rated output ot 30 horsepower under

a head of 56 feet at a speed ot 720 reYolutiona per minute

Views of this turbine are hovn in Figures S and 6 The

turbine is installed on a concrete pad located over an open

channel in the Hydraulics Laboratory at Oregon State Colshy

lege The date of manufacture of this turbine was 1915

The water was delivered to the turbine from a sump

reservoir by two pumps operating 1n parallel Each pump 1a

an 8 inch Pelton double suction centrifugal pump witb a

rating of l$00 gallons per minute at a head ot 75 teet with

a speed ot 1175 revolutions per minute Tbe inlet tlange

ot tne turbine is $pprox1mately 18 feet above the center

line of the pump

A direct current generator was coupled to the turbine

to receive tne power d veloped as shown in Figures 4 and 7 The generator is a Spr gue Electrodynamometer rated at SS horsepower with a speed range of 7$0 to l$00 revolut1one

per minute The classification is type LO 26A 2)0 volta

Figure 5 - View of Test Turbine

Figure 6 ~ View of Test Turbine

and 149 amperes lbe generator ti ld was aepar tely

excited using direct current from a motor g n r tor ampt

(l$ p 4~8)

The power output of the generator waa dissipated in

the water rheostat (3 p 488-489) shown in Figures 9 and

10 The galvanized tank contain d water ot variable d pth

on an electrode ot cast iron m aauring 1bull x 1 x 1

In the initial installation of the turbine it was

intended that the power output should be measured with a

Prony brak bull For th purpoa68 or this teat it was decided

that the brake was too instable and the generator was

substituted The platform for raising the generator the

nee asary two teet for alignment was built out of available

material In this case heavy laminated wood blocks reiashy

torced with other timbers were used and bolted through the

concrete deck (11 Pbull 36-$7)

Due to the light concrete deck the lack ot mas in

the platform and the slight misalignment in the flexible

coupling ao e vibration waa encountered It seemed to

ncr aae linearly to a maximum at the speed of bout 750

revolutions per minute Above this speed no vibPation was

noticeable The vibration waa not se~ere and does not

appear to have materially affected the test results

26

B Intrumentat1on ~ eaeur1ng Devices

The pressure head at inlet to the turbine vaa meaave4

bymeane ot two )6 inch waterbullmeroury manometerbull connected

in series as shown in Figure 8

The terminal voltage ot the generator vas meaeured by

a laboratory voltDleter with a range to )00 yolta and callbull

brated to within 15 Yolta

The armature current bull and hence the line current was

measured by a laboratory ammeter with a range to 150 amperea

and callbrated to w1 thin o 7S amperes

Tae rate ot tlow was established by weight and time

meaeurementa The weighing ank has a capacity ot 121 000

poundsJ the weight belng indicated by Toledo direct reading

scales Timing was done with a hand atop watch with clivibull

aion ot 02 second

he ~ater level in the tailrace was dete~1ned by a

hook gauge lhie was read to the nearest 001 toot

The turbine and generator speeds were eaaured by a

hand tachometer The technique of almost cont1nuoua readbull

ings of the speed gave an error ot no more than 5 revolubull

tiona per minute

c Operational Procedure

Atter the water level in the aump was checked to

insure an adequate auppl7 the puapa were primed and

27

Figure 7 - Test Generator and Plattorm

Figure middot8- Instrument Board and Field Rheostat

28

started After venting they were valved for operation 1n

parallel

The motor generator set was started to supply the

field current and the circuit breaker was closed Water

wa added to the water rheostat to the level shown in

Figure 10 ~ field current wae minimized by cutting in

all the f ield resistance in the field rheostat of Figure 8

The l2 inch gate valve shown in Figures 5 and 6 waa

slowly opened and the turbine and generator brought up to

speed The 12 inch gat valve and turbine were vented and

the pumps were checked to insure neither had lost ita prime

lhe water rheostat offers very steady load 1f the

water level is essentially constant and the water temperabull

ture 1a fixed () p 488~89) In order to maintain this

constant temperature it was decided not to circulate the

water in the rheostat but rather to allow the water to

boil thua achieving the desired result A standing wave

was set up on the face ot the electrode by the boiling

action but a atable load was eatablished except at very

low water leYels where th11 agitation led to fluctuationa

in the line current

After putting the turbine and generator on the line

maximum power was dissipated in the rheostat by redueing

the turbine speed to between oSO and Soo revolutions per

minute Salt vas added to the rheoetat wat r to increasemiddot

29

Figure 9 - View of Water Rheostat

Figure 10 - View of Water Rheostat

Separate Field ExcitationFrom Motor-Generator set Compound Water-Mercury

---shy

re Manometer

I Q)

~ 0

~

Book Gauge

Open Channel

I

Slap Reservoir

Figure 11 - Wat~r Flow Diagram and Electrical Layout

31

waiting pe~iod ot perhaps an h~ followed

while the boiling point or the water wbulls reacbe4 During

this ti+ne the manometer was vented end eheoked electrical

measur1ng 1nstlUments were connected end the hook gauge was

adjusted tor elevation

It required about two- houtte tor the generator to reach

its normal operating tempe-ratu~e_ After the water in the

rheostat and generator had reached their operating temperabull

turea it was possible to begin the taking of data

The only vaPiable which was controlled wee the turbineshy

generator speed However the upper l1ut1t of safe line

current was slightly over 100 ampJilPampPes and the eireuit

breaker would open when the current reached lOS ~ere bull

Control was exercised by means ot regulating the water

level and salt 1n the water rheo tat and the res1stsnoe of

the tield rheost t~

The etfeet ot each type ot regulation on the three

variables is shown below

Volta Aaperebull Speed

Inc Dec Inc Dee~ Inc Dec

Wa~e1 Level Inc Dec~ X

X X X X

X

Salt Concentration

Inc Dec X

X X X X

X

field Resistance

Inc Dec

X X

X X

X X

32

Jlot all methods gave the ame amount ot change in a

given variable and a period of experiment and trial led to

the following scheme starting the rune with the lowest

turbine speed the water level was high with a high amount

ot salt and the field resistance was cut completely out

Aa it became necessary to increase the speed tor each

aucceasive run either cutting in t he field resistance

decreasing the salt concentration or lowering the Vater

level would produce the desired result However decreasbull

1ng the salt concentration had to be done Without a net

gain in water which led to a tluahing procedure that was

not particularly good because cold water was introduced

which required time to heat to the boiling point Cutting

1n additional field resistance was a good method but th1a

increased the amperage possibly to the point of opening

the circuit breaker Lowering the water level was aatiashy

factol1 until the level got too low causing the current

fluctuation previously mentioned Actually it turned out

that a combination of lowering the water level and cutting

field resistance in would carry the speed from ita minimum

to 1ts maximum value it the proper choice were made each

time the speed waa to be changed At the conclusion of

each aet of runs at a high speed the water level would be

low and the field resistance high

33

TURBINE

PAD AND DECK

TAILRACE

WATER SURFACamp

CONCRETE

DRAFT TU1B INSERTS

7 5( DRAFr TUBE

FLltJI ARIA

5~ DRAFT TUBE

FLOI ARSA

Figure 12 - Sketch of Draft Tube and Test Inserts

34

Figure 13 - View of Draft Tube Insert

Figure 14 - View of Draft Tube Insert

D c __ ~s_middot hedu_le of

A number was assigned to each run The fi~st number

applies to the draft tube tlow areas

1 bull 100~ flow area or 0~ oonatriction

2 - 7S tlow area or 2$ conatr1ct1on

3 SoC flow area or so~ constriction

The second number refers to the wicket gate openings

9 over gate opening

6 bull intermediate gate opening

4 bull one h lt gate opening

The third number 14entif1ea the location of the particular

1Wl in a set ot rona made at a given dratt tube tlow area

and wicket gate opening

fnua run number 1bull4bull10 would identity this as the

tenth run ot a set made at halt gate with 75 ot the draft

tube t1ow area

Rune w re made tor a g1yen dratt tube condition

Firat tor tull 41-aft tube flow area seta ot rune were

made for the overgate halt gate and intermediate gate

conditione An insert was placed in t he draft tube and

rune based on the same gate conditions were made tor the

7S~ draft tube flow area case The insert was then changed

to allow only $~ draft tube flow area

The inserts are sketched 1n Figure 12 and photographed

ln Flgurea 13 and 14 They oonaisted of circula~ segments

36

or l2 ineh plywood mount 4 on wooden legs 10 inches high

The 1nse7te were placed in position and secured by th use

ot a-clamps on the legs and the outside ot the bottom of

the draft tube The obvious disadvantage to this method

waa the neoeasity tor draining the water from the tailrace

tor a change ot 1naert The advantage vas of course the

simplicity ot design and construction

Chapter V

DATA-A Original Data

The normal data-taking crew consisted or two men

Assuming adjustments having been made to secure a certain

turbine speed (aee section on Operational Procedure) one

man would take semi-continuous speed readings with the hand

tachometer until a state or rotational equilibrium was

reached This could be only a period or two minutes up to

ten or tifteen minutes As soon as steady speed was

assured the data taking would begin The second man went

to the weighing tank Where a minimum ot three weighingamp

were made The requirement was to get three consecutive

readings such that the ditterence between tbe smallest and

largest time did not exceed 04 seconds The time to

collect a given weight ot water was then assumed to be the

arithmetic average of the three times He then went to the

hook gauge determined the hook elevation and then

recorded the data on the data sheets The first man meanshy

while had taken readings of the line voltage line current

and manometers and checked the turbine speed by multiple

readings During the length of the run all values were

38

checked to determine mean values for recording

The minimum length of one run was about five minutes

If one or more measure ants tended to drift during the run

all values wer discarded and a new run began as soon aa

qu111br1um was stabl1shedo

B -0-al_e_u_l_a_t--d Data

The h d on the tu~bine 1 defined by

($)

The maxtmwm velocity V4 was equal to about o8 tampet per

secon4 which makes it a negligible quantity when converted

into velocity head

An engineerbulla level was used to deterine the d1ffePshy

ence 1n elevation between the compound water-mercury manoshy

meter and the hook gauge Using this value the equation

for turbine bead becomes

where z4 is the hook gauge reading

The rate of flow 1 cent

w weight or water collected average time to collect

The inlet velocity v1 vas calculated by dividing the

weight rate or flow by the specific weight of water and the

)9

area ot ~e inlet pipe This was equivalent to dividing

the weight rate of flow by 490 Then the power input to the turbine is equal to

WHpin rri

10 (6)

Also

(P ~ut) Turbine

(P out) + Generator

(P lost) Generator

The power output of the generator is simplJ the

produot ot the terminal voltage and the armature (line)

curPent The power lost in the generator can be subdivided

into copper losses and stray power losses lo evaluate

these cunes based on losses of an identical generator

11leampsured by the Department ot Mechanical Engineering were

used The loss curves are reppoduced in part in Figures

15 and 16

Determination ot generator losses proceeds as tollowau

(1) From Figure 15 detem1ne the vo1tage drop in the

armature circuit using the temperatures of 1220 F and the

meaaured current

(2) The induced voltage is t~e sum of the terminal

voltage and the voltage drop 1n the armature circuit

() Entering the induced voltage and the turbine speed

into Figure 16 the stray power loss can be determined

(4) The copper lose can be evaluated from Figure 1$

using the measured current and the temperatlll-e of 1220 P

40

25 ~------~--------~--------~------~

U) -U) - 20

f-4 ~

-~ -gt 0

0

VOLTAGE DROP

~ - i -

- bullbullbull bull - -middot-middot -+ ~- + -t--+ ~ - ~ middotbull ~-~ middott- -+----- _ -4 middotmiddot- --~-+-t---r~~ ~--+t-t- - ---t-c-++~-ulf--

0 50 75 100

Figure 15 - Curves of Generator Voltage Drop and Copper Loss

41

1200

1000

800

600

800

0

0

~-

middot--~ 1shy --1 + bull l

100

I -

150 200

IIDOOED VOLTAGB (VOLTS)

Figure 16 - Curves of Generator Stray Power Loss

_ j

-bullshy -L---- shy middot -shy

250

- r

42

(5) The generator los os equal the sum of the eopp r

loss and stray power loss

~e efficiency or the turbine is taken as

etticiency u e =P out (8)Pin

~ample pound Determ1n1gg turbine Power Output

The following data are taken trom that ot Run 1-9-1

Line voltage 1040 volts Line current 870 amperesSpeed 355 revolutions per minute

The induced voltage 1a determined as follows

Line voltage 1040

Voltage drop 90 using Figure 15 with line current of 870 amperes and temperature ot 122 degrees)

Induced Toltage 1130 volta

The power output of the turbine is determined as follows

Generator output 90$0 (line voltage z line current)

Oopper loss 7 (using Figure 15 with line current of 870 amperes and temperatUe or 122 degrees)

Stray power lose 470 (using Figure 16 with speed ot 355 revolutions per miDUte and induced voltage or 1130 volts)

Turbine power output 9527 vatta

or turbine power output 1s 12z2 horsepower

43

The conversion of the calculated data to a constant

head is based on the conventional assumption of constant

efficiency regardless of turbine head For a constant head

ot 81 teet a purely arbitrary figure the tollowing relashy

tionships are ass1lJiled to be true

I ____L (9) (i)l72

(10)

For these two values the specific a peed may be combull

putedt

N t Jt VPt (11)8 243

Chapter VI

~RESULTS

A -Pr_e_ae_n_t_a_t_t_o~n g Reaultbull

Graphical presentation ot the results ot this te1t

are given as follows

Figure 17 -Turbine characteristics with 100~ dratt

tuba 1low area

Figure 18 - Turbine characteristics with 7S dratt

tube tlow area

Figure 19 bull Comparison ot power and etticiency at

over gate conditions between 100 and

75~ draft tube flow area

Figure 20 bull COZQparison of power and ettic1ency at

halt gate conditions between 100~ and

7S~ draft tube flow area

Figure 21 bull Comparison of power and etticiency at

over gate condition between 100~ and

So dratt tube tlow area

Figure 22 - Comparison in variation ot apec1t1c

speed between 100 and 75~ dratt tube

tlow area

50

45

20

-bull - 1--shy40

bull J-~ 30

~ ex

~ 20

~~ ~ -)q

I

~ - _

- -

10~ OF DRAFT TUBE FL(Jif AREA

CONSTANT HEAD OF 8l FEST10

POIER OUTPUT EFFICIENCY SPECIFIC SPEED

0 ~--------------_--------~------~------~ 400 600 800 1000 1200 1400

TURBINE SPEED (RPM)

Figure 17 - Turbine Char~cteristics with 100 Draft Tube Flow Area

50

46

-bulllle

~ 7 ~ OF DRAFt TUBE FLOW AREA

0 -~~-rl C05STAMT BEAD OF 81 mET 1J~

POIER OOTPUT ---+- ---o ~_H EFFICIDCY ~ I shy

bull ql SPECIFIC SPEKD - ~ -

bull ~ J 10 L rmiddotr- r- -

bullz- I

~~ 30 ~~--~----~~-

20 ~ ~ middot-shy

26

~~ 25

~0 ~r-----i (

Tbull -bullshy

400 600 800 1000 1200 1400

TURBINE SPEED (R PK )

Figure 18 -Turbine Characteristics with 75 Draft Tube Flow Area

47

EFFICIENCY 60

1-----shy

-~ 50~--~--~~-~middot middot middot middot r~-~----~~~~---4~-r~-~~gtt

II

POWER~ J ~ bull bull

u I

sH

40~------+-------+---- -~~--~~-~~~~

~----~rl 1 bull

I

I

0~--------------~------_------~--------

~ -OVER GATE CONDITION

COIJSTANT HEAD OF 81 FEET

0 o 10~ DRAFt TUBE

_-- _ 7~ DRAFT TUBamp FLON AREA II

10_~-----+--------r-------r----~~

400 600 800 1000 1200 1400

TURBINE SPEED (RPM)

Figure 19 middot - Comparison between 75 and 100 Draft Tube Flow Areas of Power and Efficiency at Over Gate Conshydition

48

t

bull --4 r ~- ~ middot~

70 1-----------+-~~~~~+middot ~ ~~ middot middot -~~--~~--------~~----~-+1

-~-

Atbull bull

lla-

60

amp0

40

20

10

oampOO

t _ - - ~-+- - -~-

l2 GATB COJIDITIOJJ

COJISTABT HJW) OF 81 JBET

o 0 lOQ( DRAFl TUB8 FLOI AREA

e-- - e 75 DRAFT TUBE FLOW AREA

800 1000

- r-

~

TURBIbull SPBIID (RPII)

Figure 20 - Comparison between 75 and 100 Draft Tube Flow Areas of Power and Efficiency at Half Gate Conshydition

49

60

50

-40

bull 30

IIQbull

20

10

0

400

- t - ~

EFFICIENCY

_J bull - bull bull

~ r r middot t -+ shy L -t -

OVER GAD COliDITIOI

CONSTABT BEAD OF 8l FBB

o o 10~ DRAFt TUBE FLOI ADA middot--- 5~ DRAF TUBE FLQPi AREA

600 800 1000 1200

Figure 21 -Comparison between 50~ and 100~ Draft Tube Flow Areas of Power and Efficiency at Ove~ Gate Conshydition

50

25

20

15

10

0

Figure 22

~- T -4 -t- -l --~-

t-~ I

middot --~- t ~---- _ __ _ + --

----~- --r-- --

~-=J-~-=-~ -==~ _ ~- -- ---f---1 - shy

CONSTANT HEAD OF 81 FEBT

o--o 1~ DRAFT TUBE FLltll AREA

75C DRMT TUBK FLCIJ AREAmiddot--middot-middot 600 800 1000

TURBINE SPEED (RPK)

Comparison of Specific Speeds for 75 and 100 Draft Tube Flow Areas

51

B Discussion 2 Result

Consideration of Figures 17 and 18 indicates the

overall eftioi ncy pattern or hill is significantly or

rounded for the 7$~ flow area than for the 100~ flow area

bia implies a greateP efficiency is possible at speeds

leas than or greater than design speed with an insert in

the draft tube However the muilDum efficiency is lemiddotas

Direct comparison at over gate conditions is made in

Figure 19 ~e same general trend is noted tor both the

etticiency and power curves for the 7$~ flow area case

The eurves show higher values at overspeed than do the

correaponding cWvea for the 100 flow area case It ia

not clear whether the curves have been shifted by the dratt

tube constriction or whether the curves simply bulge past

the normal curves at both overspeed and underspeed condishy

tions The power curves apparently peak near the aeme

point bullalthough maximum power is still obtained with the

normal draft tube area

For the comparison at halt gate operation shown in

Figure 20 a general improvement has apparently been made

by restriction of the draft tube flow area At every speed

the etticienoy and the power is greater for the restricted

tlow case The two ett1o1ency curves and two power curvea

are practically parallel throughout the speed range ot

teat

As the flou aroa i e decreased still farther a s1gn1

ticant change appears Reterr1ng to Figllle 211 tor the $0

flow area curves it a obvious that exit losses have

become excessive at the overgate condition because the

efficiency and power are everywhere leas than tor the case

of normal draf t tube area

Earlier it was pointed out t hat 1t the r esult s 1nd1bull

eated an increase in both power and ef tieiency- t hen it

could be assumed tha t the additional los s i ntroduced with

the draft tube insert is less than the diminished losses

due to leas shock losa and water passage losses For the

places where both the efficiency and power have been

increased we can assume that the insert has improved turshy

bine performance

For the places where the power haa been decreased

nothing can be said as to the elimination of ampbock loss

because the new lose present with the drat tube insert has

overshadowed any gains in eftecti Ve head upatJ-eam of the

insert

Near the peak of the efficiency hill howeve~ it may

be pointed out t hat shock loaa ie a minimum with a normal

draft tube and the insert merely adds an additional loss

with the resultant decrease in maximum efficiency tor the

7$~ flow area case

Perhaps the most s1gn1ticant set of eurves is shown aa

53

Figure 22 In this graph values of specific speed tor the

75 and 100~ flow area cases for both over gate and one

halt gate openings are plotted against turbine speed At

every speed and both gate openings the value ot specific

speed for th 75~ flow area case is greater than that for

the 100 t1ow area ease

Since the head is a constant for both situations this

may be interpreted in either of two ways trom equation

(11)

(1) For the same turbine apeed restriction of the

draft tube t1ow area resulted in greater turbine power

(2) For the same power amputput the turbine with 75~

draft tube flow area operated at a greater speed than did

the one with 100 flow area

Since the required diameter of a turbine varies

inversely with the speed the second interpretation could

be stated such that a smaller turbine could be used to

develop the same power output

Whether viewed trom the aspect of increased power

greater speed or reduced size the performance of the turshy

bine with reduced draft tube flow area is superior to that

with the nolmal flow are in the draft tube

The curve of specmiddotific speed versus turbine speed for

the so draft tube flow area case at over gate cond1t1ona

was not included in Figure 22 This curve lies below that

for the 100~ flow area c se at all speeds

In elaboration ot the second interpretation of Figure

22 attention is directed to the relative magnitudes ot

increased apee1f1c speed tor the two gate openings Assumbull

ing that the increase in specific speed implies a shift ot

the power curve to the right along the turbine speed scale

the power curve would be shifted more tor tbe halt gate

opening than tor the over gate opening

It thia trend could be extrapolated to the other gate

openings the tendency can be seen tor the line ot beat

speed to rotate toward the line of the operating speed as

illustrated in FigtU-e ) The advantage of this has already

been discussed

This particular turbine has a low specific speed tor a

reaction turbine Aa the rated value of apecitic apeed tor

reaction turbines increases the line ot beat speed departs

even more radically from the line of operating bullpeed It a

test similar to this were conducted on a reaction turbine

ot gleater specific speed it is pJobable t hat the rotation

ot the line of beat apeed would become more p~onounced

The scheme used in th1a teat had two obvious dr wbull

backs The first was the decision to leave all the wicket

gamiddottes installed tor all conditions ot the draft tube

These gates predominated in control of the tlow The

inserts added to the draft tube merely acted as auxiliary

55

contrGla

The aecond drawback was the choice or device to place

in the draft tube The reasons foll selection of this type

of device have been previously mentioned It is to be

anticipated that adaptation ot dratt tube flow control

would result 1n a better device for an actual turbine

installation Such apparatus might take the form of a

pneumatic bladder or a h7drau11oally operated variable

venturi section in the draft tube It is conceivable that

the gate as used in this test might be adapted also

Chapter VII

OONCLtJSIOfS

From the results of this test the following eonolubull

e1ona aa to the effect ot a variable draft tube flow area

on the performance or a r action turbine may be drawn

(1) The effect ot a variable draft tube tlow area 1a

generally favorable upon the operat1Gn ot a reaction turbull

bine because or the tendency tor the line or beat speed to

rotate toward the line ot operation This resulte in

better performance of the turbine at partbullloads

(2) he etf1o1ency eh111 tor the turbine beeomaa JDore

tlat at the top leading to a smaller max1JilWD effic1enc7

but e reater etticieney at other pointe of operation with

the insertion ot an auxiliary control ror the rate ot tlov

in the draft tube

(3) The power output of the turbine will increase at

over speed over gate conditione as well a at part gate

conditions with the proper amount or draft tube eonatr1cbull

tion or flow

(4) It is possible to eliminate at least partially

eddy type shock loss by tho introduction ot flow control

in the draft tube

BIBLIOGRAPBl

1 Addison Herbert A treatise on applied h-draul1cs New York Wiley 1954 724 Pbull

2 Allen o M and I A Winter middot Co111parative testa on experimental draft tubes Tranaact1ons ot the American ociety ot Civil Engineers 87t893bull970 1924

3 Barrows a E Water power engineering 3d ed ew York McGraw-Bill 1943 791 Pbull

Bovet G A Modern trenda in hydraulic turbine design4middot in Europe Tranaactions of the American Society ot Mechanical Engineera 75975bull993 1953bull

s Oreager William P and Joel D Justin Hydroelectrichandbook 2d ed New York Wiley 19$0 1151 Pbull

6 Daily Jamea w Hydraulic machinery Int Hunter Rouses Engineering hydraulics Hew York Wiley 19$0 p 8$8bull99

Daughertybull Robert L Bydraulie turbines ew Yorkbull7middot MoGrav-Hlll 1920 281 Pbull

8 Daugherty Robert L Inveat1gat1on of tne performance ot a reaction turbine ~anaactiona or the American Society ot Civil Engineers 7811270bull1304 1915

9 Davie L M Model and prototype testa Int Trend in hydraulle turbine practice symposium lranaactions ot the American Society ot Civil Engineers 1o63S3middot368 1941

lfJ Doland James J Hydro power engineering Hew Yorkbull Ronald 1954 209 Pbull

11 Gandy Theodore s and Elmer c Schacht Direct curshyrent motor and generator troubles operation and repair New York McGraw-Bill 1911 293 Pbull

12 Gibaon Arnold H Hydraulics and ita applications5th ed London Constable 1952 813 Pbull

58

13 Button s P Component loases in Kaplan turbinebull and The prediction of efficiency from model tests Probull coedings of the Institution or Mechanical Engineers168743-762 1954

14 Knapp R T~ Oavit t1on mechanics and its relation to the d sign or hydraulic equip ent Proceedings or tne Institution ot Mechanical Engineers 166150bull16) 1952

15 Langsdorf Alexander s Principles of direct curHnt mach1nee 5th ed New York r~cGrawbullH1ll 1940 746 Pbull

16 Lsrner Chester w Characteristica of modern hydraubull lie turbines Trans e~ions of the ~~erican Society ot Civil Engineers 66306-386 1910

17 Linsley Ray K Jr and Jobulleph B Franzin1 Eleshyments of hydraulic enginebullring New York McGrawshyBill 19$5 $82 Pbull

18 Mead Daniel w Hydraulic machinery llev York McGraw-Hill 1933 396 Pbull

19 ead Daniel w Water power engineering New York McGrawbullRill 191S 843 Pbull

20 Mockmore Charles A Part gate operation at water turbines Corvallis Oregon State College Department ot Civil Engineering 1933 11 numb leaves (Unpubshylshed typescript)

21 Mockmore Oharles A Flow characteristics in elbow dratt tubes Transactions of the Amez-ican Society ot Civil Engineers 103402middot464bull 1938

22 Moody L F Hydraulic machinery In c v Davis Handbook ot applied hydraulics New York McGrawshyHlll 1942 1082 Pbull

2) Ptau At-nold Hydrbullulie turbine handbook ld ed Milwaukee AllisbullOhalmers ManufactUIing Company 1948 70 Pbull

RheingalUI w J Recent developments in Francis turshybines Mechanical Engineering 74189-196 1952

25 Russell George E Hydraulica 5th ed New York Henry Holt 1942 466 Pbull

26 Safford A and E P- Hamilton American mixed tlow turbine and ita setting Tranampactions or the Amerieal Society of Civil Engineers 851237bull1)56 1922

27 bull Spannhake W1lhe1Dh Problems or modern pump and tur b1ne design Transactions of the American Society of Mechanical Engineers 56e22$-248 1934bull

28 Sutherlandraquo R A Better ethod or representing and middot tudying water turbine performance ~ansaetions ot thmiddote American Society of Mechanical Engineers 68t675bull 686 1946

29 Teats ot five models or draft tubes tor turbines Engineering News-Record Pbull 182-184 Aug 2 1923

30 White w M American hydztaulic turbines Mechanical Engineering S2t390bull39S 1930bull

31 White w M lhe hydraucGne rega1ner1 its developmentand appl1eat1ons 1n hydroelectric plants Meohanlobulll Engineering 43t37Sbull380 1921 middot

32 Winter I A Economic principlebull in designbull Int Trend in hydraulic urbin practice bull a ampoeiumTranaaot1ona ot the American Society ot Civil Engineerslo6332bull3S2 1941

33 Wiel1cenua G F Fluid mechan1ca or turbo-machineryNev York McGraw-Hill 1947 613 Pbull

APPENDICES

c

Appendix A

NOATIOB

A Angle between the absolute velocity vector and the tangent to the rwmer Subscripts 1 and 2 refel to entrance and exit ot the runner blade

B Angle between the relative 1elooity vector and the tangent to the rwmer Subscripta 1 and 2 refer to entrance and ezit or the runner blade

Angle between the tangent to the runner blade tip and the tangent to the runnel- Subscripts 1 and 2 reter to entrance and exit of the rt1rmer bladebull

Blade angle-gate opening conetant defined by equation (1)

e 09erall efficiency

g Gravitational acceleration assumed constant at 322 teet per second per second bull

H Turbine head detined by equation ($)

m Exit loss coeft1e1ent

Turbine speed expressed in revolutions per minute

Turbine speed under a constant head of 81 teet

specitic apeed of the turbine under a constant head ot 81 teet

p Power output in horsepower ot the tvbine

Power output of the turbine Ulder a constant head ot Sl teet

Pl- Pressure head at entrance to the tUlb1new

l1 Peripheral velocity ot the runneP Subacr1pta 1 and 2 refer to entrance and exit ot the JUnllampr blade

62

v Relative velocity reaulting trom the combination ot the absolute water velocity V and the runner periphshyeral velocity u Subscripts 1 and 2 refer to entrance and exit ot the runner blade

v] Relative velocity vector necessary to produce a tanbull gential entry into the runner blades

V Absolute water velocity Subscripts l and 2 refer to entrano and exit ot the runner blade

v2 Velocity head Subscripts 1 and 4 reter to the ~8 entrance to the turbine and the tail~ace wate~

w Unit weight ot water assumed constant at 624 pounda per cubic toot

V Weight rate ot flow in pounds per aeooncl

XX Velocity component ot ahook See Figule 2

Z Elevation head Subscripts 1 and 4 reter to entrance to the turbine and the taibace water surfacebull

Appendix B ORIGINAL DATA-Run

lfwnber

0-4-1 0-4-2 0-4-3 o-4-4 o-4-S o-4-6 0-4-7 0-4-8 0-4-9o-4-lo o-4-11 o-4-12 0-4-13

o-6-1 o-6-2 06-3 o-6-4o-6middotS o-6-6 o-6-7 o-6-8 0-6-9 o--6-lo o-6-11

Speed

rmiddot2middotbullmiddot(1)

336 38$ 451 S$9 620 669 6lt)$ 120 787 860 932

102imiddot109 bull

352 355 443middot 543middot 620 654AJs32

911 1001 1111

~essure Head rt (2)

410 410 416 426 431 43-7 439 44-9 452 467 482 soo $1 bull $

350 351 35middot7 )66 37-9 37-9 392 41 bull 3 43middot3 460 489

Elevation Bead

fjj $7 $7 $7 $7 $7 $7 51 57 5-15858 $8 58 56 56 $6565656 51 575As5a

Velocit Head

flj 07 07 07 06 06 06 06 os 05 os0404 03

09 09 oa o8 o8 os 07 07 06 o~o

Total Head rt ($)

47middot4 4A44 o 489 49-4 soo $02 $11 $14 $29 5imiddot45 2 576

41 bull $ 416 421 430 44middot3 44middot3 456 47-7 496 523551

Plow

lbtjec

326 324middot317 311 306 30029middot28 middotmiddot middot 386 275middot260 240 218

359 36~35 bull 349 345middot 339 330 318 300 273 240

Line Potential

vyqjbull 1060 1220 ~-0o 1920 2150 2000 2$60 2000 1940 18)015io11 o

1000 1100 139bull5 1760 1925 16$0 1620 1610 1540 1330 870

Line Current

amlscs 960 900 830 740 730655 70bull 0 530 660 600 5imiddot54 6 )60

982 930 860 780 ~3-545

79-5 74-5 670 560 370

P

Appendix B ORIGINAL DATA (Continued)

Run Number

Speed

Pbulltmiddotbullmiddot )

leasure Head ft(2

Elevation Head tt(J)

Velocity He-dfmiddotj

Total Bead tt($

Flow

lbstsec( )

Line Potential vo~ta( )

Line Current

amjs (sect

0bulllt)-1 0-9-2

3ll6 398

28o ~~1

$6 56

1o 10

346 347

390 365

1ooo 1190

aao 835

0-9-3 0-9-4 o-9-S

472 565 632

292 305 312

$6 s6 56

10 o9 o9

)$8 J7~o 37~7

381376 37o

1)6614oo 141o

820 ass ass o-9-6 0-9-7 0-9-8 o-9-9 0middot9-10

680 120 762 844 920

)24337346 366 390

56 $6 56 57 $7

09 os o8 oa 07

)89401 410 431454

367~ 357348 34o 322

1400 1J6o l36o 1310 1170

843 820 7957So 67~0

0-9-ll 0-912

1001 1100

41 bull 7 45-3

s 7 6~0

06 os 480 $18

299 268

980 65$

560 36~5

1-4-1 1-4-21-4-l1-4shy1-4-5 1-4-6 l-4-7 1 4-8 1-4-9 1-4-10 1middot4-ll 1-4bull12

354middot452 562 62q 674shy102 752 760- 863 932

1022 1100-

)82389 4014oa 416 41--7 423 428 44-2 45-7 486 49-2

51S757 51 5-7 5middot15zs sa $8 58 59

07 07 06 06 06 06 06 os o bull o 04 o J

446 45-)46middot4 471 ti7-9480 q86 491505 $19 548 55-4

)28 320 311 306 300 295 291 286 269 2582iimiddot21 bull

1080 14Lo 1550 153-5 1470 141-0 1385 1310 1310 1230 1120 855

970855 875 91-0 94~0 975 966 995 860 77-S 610 4fo

0 ~

Appendix B ORIGINAL DATA (Contirmed)-Run Speed Pressure Elevation Velocity Total Flow Line Line

Number Head Head Head had Potential Current rtjjmbull t~ bttec vyfs am~a12) ( ) ti fli 8

1-6-l $6 33$ $6 0bull9 400 364 1100 93 0 1-6-2 41 34laquo2 $6 oa 406 JS7middot iios a5s l-6-3 500 3~0 5bull6 os 356 1 1 o aos 41middot~1-6~4 35bull4 5-6 oa 41middot 352 16~0 82 0 5~1-6-5 5 bull 36_2 Sbull6 08 42bull6 349middot 161 ~ 0 86~0 1-6-6 622 366 $6 oe 43bull0 345middot 158 0 88~$ 16-A 649bull 37bull1 56 os 43-S 342middot 1570 895 1~- 386 57 07 46-0 192 ) 125A44 333middot 1-6-9 3) 404 5middot1 07 468 317 1620 675 1610 911 42-4 5-7 o6 48-7 298 168 0 61 0 1-6-11 999 451 56 os Sl ll 276 ~2-0 530 1-612 1115 485 58 04 54middot7 238 90 )3 0

1middot9-l 355 279 56 10 )45 385 1040 870 1-9-2 399 28J $6 10 )49 38$ 1140 86 5 l-9-3 ~ ao 291 56 ~0 35middot1 J8J_ JJ6o 815 1bull9-4 579 303 56 09 )68 375middot J4JO 830 l-9bullS 40- 313 )6 09 31middot8 370- 1460 82~0 1-9bull6 679 2) 56 09 3 bull8 364middot 1670 710 l-9-7 682 319 56 o9 384 ) 62 1460 79 5 l-9-8 724 33middot5 56 o8 399 3$6 bull 1480 76 -5 1-9-9 762 34middot3 $6 0 bull 8 407 )48 14910 13middotS 1-9-10 833middot )60 5middot7 os 42$ 339 144$ 686 1-9-ll 926 39middot1 5-7 07 455 318 1290 600 1-9-12 1000 41middot3 0-6 476 298 1115 510$ ~ 1middot9-13 1105 452 s o4 $14 2$6 710 )10

~

Appendix Bt ORIGDIAL J (Continued)

Run Speed Pressure Elevation Velocity Total Plow Line Line Number Head ltead Head jlamp$d P()ten~ibulll Current

r~~~m ft ft lbs~seo voltattj rgj twimiddot t 1 t2gt lt3 ou t ( rt

2-9-1 384 289 S 6 10 35 5 1400 1170 810 2-9-2 443middot 29$ $6 ltimiddot9 360 379middot 11(0 87$ 2-9-J 536 30bull 3 sc 09 )68 374middot 1)40 84 bull) 2-9-4 571 306 $6 09 3~1 372 120bull 0 955 2-9-5 623 316 S6 09 J l )6S UJSo 77$ 2bull9-6 669 327 S6 09 )92 )61 1240 905 2-9bull7 712 )39 56 os 40-3 351 12(0 86 bull0 2-9-8 ~5$~ J48 56 oa 412 348 1290 81 bull ) 2-9-9 04 )63 56 oa 42-7 339 12ltJO 76$ 2middotmiddot9-10 8$2 376 5middot1 07 440 33~- ~ o 710 2-9-11 955 394 5-1 o6 457 300 1100 506 2middot9-12 1000 421 $7 06 48middoti 295 1020 $18 2-9bull13 110~ 463 56 05 $2 267 620 3~0

oshy0

Appendix Gt CALCULATED DAgA

Turbine Run Generator Generator Turbine Turbine Efficiency Turbine Turbine Specit1c

Number OutputKWlt21

Loa~Jes KWlol

Outut K bull (H)

Input RP 12)

middot Percentlt13gt

Speed r~Jmiddot(

0ltput HP ~1

Speed r-m

( 6) middot

o-4-1 0middot4-2 0-4-3 0-4-4 0-4-5 0-4-6 O-qmiddot7o-4-8o-4-9 0-4bull10 0-4-11 o-4-12

1018 1o9a 1220 1)62J40214oa1J4oo 1357 1320 1164 997 718

046 o59 071 092 096 1071oo 134 104 100 109 107

14261sso 17)01948 2008 20322011 1999 19 09 1708 14-84 11o6

281279 27-7 276 215 273271 268 268 26h 258 24-5

soa 555 62$ 705 7)1145 742 74-6714645 51s 45-1

440 sos 585 720 195 sso sao 9$$ 985

1065 1135middot 1230

318 357 319 416 422 419412 39middot9 378 324 260 191

102 12bull4 148 191 21bull 3 22o 233 249 24924middot9 238 221

0-4middot13 418 104 699 228 306 1300 117 18)

o-6-1 982 045 1376 271 $08 496 376 124 o-6-2 o-6-3 G-6-4o-6-5 0-6-6

1023 1200 13 73 J415 139h

051 0middot66 oaa ()bull 96 088

14-39 1696 1958 2026 1986

276 27middot4 273 278 274

$20 61 8 717 7)0726

q95615745 8)5685

390 ll5middot3 sos soo 490

127 170 218 243 2$$

o-6-7 o-6-8 o-6-9o-6-lo

1288 1199 1032 7-45

o9o 094 09$ 096

1846 1733 1511 1128

274 276 271 260

67S 629559 43middot4

980 1085 1165 1245shy

436 )83316 21bull 7

266 276 270 239

0-6-11 322 1oo 566 2141 2JS 1350 101 177 0 --4

Appendix C CALCULATED DAlA ( Continued)-Run

Number Generator Generator

Out2ut Losaes xw LW- 12gt (lO)

Turbine Out2ut

ltPlJ

Turbine Inat lfP Jig)

Etpound1e1ency

PireentDl

Turbine Sed x-~m( 1

Turbine OutEut RPJl)

Turbine Specific

SeeedrIbullntbull

( 6)

o-9middot1 0-9-2 0-9-3 o-lt)-4 09-$ 0bull9-6 0-9-7 0-9-8 0-9-9 0-9-10 o-9-11 0-9-12

aao 994

111$ 1197 1206 1180 11)21081 982 784 5-49 2)9

0middot45oss o6$ 070 07$ 0-77 (l77 or~ o s06o 8 096

123~ 1402 1$80 1698 17bulllS 168$ 16bull18 ~middot5430 1151 a~J4 9

24middotgt24middot3248 25~25 260 260 259 267 266 26middot1 2S2

sos 577 63-7 671 676 650 621 60036J4

327 178

$) 610AlO 3$

92S 980

102$ 1070 1157middot 1230 1300 137Smiddot

44middot4 soo 523 ssomiddot 540so6 46-5 432 368 274 18~8

J46 176 21-1 255 2802s_A 28 289 288 265 231 168

1-4-1 1-4middot2 1-4-3 1-4-4 1-4-5 1-4-6 1-4-7 1-J-8 1-4~9 1-4-10 1-4-11 1-4-12

10bull48 1231 13-S6 1397 1)821375 1))8 1303 1127 953 683) 51

048 067 o7A07 0 bull79 oa1 oss o bullao osa 0lt)0 096 099

J468 1740 1921 1978 1958 19$1 1911 lSSi162 1)98 1045

603

266 264 262 262 261 2512$7 2$6 24middot7 24-3 233 217

551 660 13middot3155 75-6 7~-97 middot4 72$ 67 51middotJ 44middot9 21middot1

475 605 A4220

875middot 910 970_

1000 1090bull 1166 1243 1330

5816

44middot444middot5 430 427 412 392 329 273 188 l0-7

117 101 204 22$ 2)7245 2562sa 257251 222 179

a-C))

Appendix Ct CALCULATED -DATA ( Ocntinued)

1-6middot1 1023 o$2 14-41 26S 505 41~6 26~

54middot5 13middot3l-6-2 1201 067 1boo 625 47-9 17shy~middot41-6bull3 1296 oA9 1 middot43 26 9 700 so5 20bull 4 l-6-4 l3j5 o 0 19~09 268 71bull3 A5o 514 222 1-6-5 1) 5 o81 19(gt4 271 725 51-5 238 l-66 1398 081 198) 27-0 736 8 S13 252~-middot l-6j 1405 083 199i 211 733 885 $middot06 2$9 l-6 13middot9~ 103 2amp 0 279 71 8 985~ 467 ~-69 1228 1 bull 02 17-SS 270 661 109$ 407 ~3~ l-6bull10 1025 100 lSll 26i 573 1175middot 27~S32middot~l-ampu 153 1-00 llft3 26 444 1270 22 24bull8 1bull6-12 294 100 52a 231 22 3 1360 95 172

1-9bull1 904 048 1275 2J4Z $28 S4$ 459 1$2 1-92 98$ oss 13-92 24middot4 57-0 6JO 49bull1 176 1-9middot3 1110 066 1$76 24middot9 63middot4 I2o 536 21-7 l--9-4 1187 072 1685 251 66$ 5 $$ bull 0 261 1middot9-5 llltJ7 1710 25middot4 67-3 93$ 536 28~20-671middot9-6 1186 o 8 1708 25-7 67) 980 $15 2691-9- 1161 oBo 1660 2$middot3 6$6 990 508 29-1 l~- ll-32 oB) 16sect0 2$8 632 1030 471 291 1-9bull9 109$ oa5 2$7 614 1075 29S~middot 0 4imiddot41-9-10 9~91 oas 262 S$1 1150~ 3 o 292 1-9-11 o9o u57 12JiO 21gt 26-77middot74

-45 26sect ~middot91-912 $69 091 sas 25 middot3 1)0$ 196 2J-8 1-9-1) 220 098 426 2)9 178 1390middot 84 16 6

0 0

Appendx C CALCULATED DATA (Continued)

Turbine Run Generator Generator lurbine Turbine Eft1e1eney Turbine lurbine Spee1f1c

Number Output Losses Outit Input Speed Output SPed middot k_-V KW R _ H_bull_P Percent r Thm HP rpm_ (9) tlo) 11) middot (12 _) (lJI ( ) (1$ (14)

2-9-1 9--46 055 1)62 258 528 580 164 2-9-2 1024 056 248 58 4 665 4 9 191iimiddot48 4~middot0 2-9-3 1132 067 05 2$0 641 795 52q 237 2-9-4 1148 065 1027 2$1 -~8 845 525 252 2-9-5 11 77 oso 16-83 253 6 910~ 522 270 2-9 6 1122 071 1600 251 622 960 47-5 2722-9-A 1092 015 1562 257 608 1010 445 2z12bull9- 1052 079 1514 261 580 1060 41middot7 2 2 2middot9-9 986 o82 ]429 26) 542 1105 372 277 2-9-10 915 086 1340 268 500 1160 334 27-6 2-9-11 638 087 972 254 )81 1270~ 229 250 2-9-12 )28 090 828 259 )19 1295 179 226 2-9-13 192 094 383 2$ 6 150 1370 7 3 152

-3 0

Page 17: The Effect of A Variable Draft Tube Flow Area on the

10

VELOCITY VECTOR DIAGIWI

TYPES OF SHOCK LOSS

xbull X

IMPACT BDDJ

XX 1a Teloc1t7 caponent ot shock

Figure 2 - ~bine Runner Vector Diagram$ and Shock Loss Diagrams

11

2 shock loss (XX gt2g

C =sin (BimiddotAl)Let (1)sin Bi

(UlmiddotCV1)2Then shock loabull (2)- 2g

For a given gate opening C ia a constant ranging

from about 14 to 10 For a well designed wheel it is to middot

be expected that C would be approximately equal to U1V1

at rated conditions ie at point of maximum efficiency

This point will occur in the neighborhood of 3~ to 78

gate opening for moat turbines For overgate conditions

the angle A1 becomes larger so the value of C would

decrease For gate openings below rated conditions t he

angle A1 decreases and C would decrease One could expect

a fairly uniform decrease in t he value of C as the gate is

closed from t he overgate position

The velocity v1 is approximately constant for any

turbine speed since the area and rate of flow both decrease

fairly uniformly However for a given gate opening the

velocity V1 will decrease with increased turbine speed

From the foregoing comments and equation (2) the

following trends can be established

(1) For constant turbine speed the shook loss curve

will be close to parabolic in shape concave upward and

have its maximum near t he point of complete gate closure

--

12

and its minimum near the rated gate position

(2) For conatant gate opening the shook loss curve

will approximate a symmetrical parabola with its vertex

the point of minimum loas located at the rated condition

of operation (7 Pbull 79)

c Exit Loas

It can be seen from Figure 2 that the exit loss from

the turbine would be v222g if no draft tube were present

The addition of a draft tube permits the gradual reduction

of velocity by an increase in cross sectional area between

the exit of the runner and the exit from the draft tube

The exit loss and the frictional loss encountered in

the draft tube may be placed together in the expression

m va2 (3)Exit Loss ~---2g

For the ideal case of no friction in the draft tube

m is equal to the square of the ratio of the area at exit

from the runner to the area at exit from the draft tube

In an actual turbine installation however friction

will change the value of m (7 p 84-85) to somewhere

between that for the ideal case and a maximum ot 10

In the interest of maintaining a minimum exit loss

the turbine should be designed and operated so the velocity

V2 will be minimum This will occur when the discharge

13

vector is at right angles to the tangent to the runnerbull

ie the angle A2 1e ninety degree bull It ia to be expected

that this condition will be tultilled near the design con~

d1t1ons ot the ~bine

Current design praetiee 1 to have a small component

ot v2 in th$ direction of turbine rotation at rated condibull

tion$ ltS p 938)

For a constant turbine speed the d1seharg or exit

loss is ess nti lly a constant

For a constant gate opening the exit lo s curve is

aptrroximately a symmetrical pa~abola with ita vert x the

point or minimum loss located at a slightly lowe~ speed

th n the turbine rated speed (7 Pbull 79)

Chapter III

PROPOSAL OP ALlERMAlE MFTBO 0 CO TROL-A lz ~ Location 2 Control

Thua tar only practice and theoretical aspects appemiddotrbull

taining to present day turbinea have been d1acuaaed It

haa been presented that control over the ~bine ia ezerbull

oiaed b y manipulation of the wicket gatea located 11101led1bull

ately preceding the runner These gate - upon rotation

modify both the magn1tu4e and the direction ot the entering

velocit7 Moreover it has be n shown that a simultaneous

change in these two variables leads to inefficient operabull

tion by the introduction of shock loss he farther the

point of operation a from the rated conditione the more

aerioua ia the ahock loss encountered

Any attempt to better turbine pertorance at other

than rated conditione and tbne flatten the top ot the

etticieney hill8 must concentrate upon the lessening ot

the ahock loaa It 1a a aumed that 1 provement in the

scroll case gates and runners would lequ1re sueh pertecbull

tion 1n machine work and metal$ as to be prohibitively

expensive

It ie surmised that any move to elblinate eYen parbull

tially the shock loss would require separate control ovel

l$

the flow and gate exit angle Since it is improbable that

d1~ect1on could be controlled at any location other than

where the gatea are situated in current turbines it will

be assumed that guide vanes will be necessary regardlesa or the method used to control the rate of flow

The primary purpose ot th se guide vanes 1s that or control over the direction ot the incoming water They

should be free to rotate in much the same manner as ordibull

nary wicket gates in order to exercise control over th

turbine speed

If the rate ot tlov is to be controlled elsewhere it

must be modified either in the penstock or the draft tube

Devices that could be used are standard valves gates

variable orifices variable venturi sections and associated

flow regulating schemes

Alauming it were decided to locate such a device upbull

stream of the turbine it would be necessary to allow disbull

tance tor the flow picture to become reestablished prior to

entry to the turbine A contused flow making transit of

the turbine passages would only contribute additional loesbull

ea Such a distance allowance would be perbapa 20 to So

diameters (2$ Pbull 119-123) In large penstocka th1a would

repreaent a considerable distance Which from the viewbull

points ot convenience and control would be undesirable

Attempts to ascertain the effect or additional tlov

16

reduc ion at the wicket gatctsmiddot wae ade 1n the lfadraulioe middot

Laboratory of Oregon St middot te College in 1933 (20) Three

d1tterent thode ot reducins the tlow were t~ied

(l) Locking in the cloeed position pairs or wicket

gatea located opposite to eaeh o~er on the -periphery ot

the wheel

(2) Locking adjacent gates in an open position by

inserting blocks of wood between them and

()) Suocess1vely looking adjacent gates in the closed

position

The results indicated a arked reduction in both power

and efficiency when compared to the curves tor normal gate

operation However it was demonstrated that it was poae1bull

ble to ahitt the power and tfieiency curve ill relation to

turbine apeed lbis important feature will be diacussed

later

ihe main conclusion of the investigation was that conbull

trol by the conyent1onal wick t gates was auper1or to other

methode egtt control exercised at the gates the aelvebullbull

It would app$ar that the bebullt location tor flow conshy

trol would be in the draft tube since none of the objecbull

tiona prev1ously mentioned wou~d eziat there

As bas been stated previously the sole object or the

17

18

turbine is to produce power as etfic1ently as possible

The equation tor the power output of a turbine () Pbull 227)

PaWHe HP (4)55o bull bull Assuming the head 1a constant and a g te located in

the draft tube decreases bhe rate ot flow the power eu

only be increased if the etticiency increases

The ettective head Gn the turbine 1s conventionally

d r1ned as the difference between the auma ot the elevashy

tion head pressure head and velocity head at the entrance

to the turbine casing and the tailrace ($ Pbull 872)

lt ie recognized that the theoretical treatment ot

shock loss as given is highly approximate and serves only

to dictate certain trenda For example the area at xit

rom the wicket g tea CfUl be measuPed with some exactness

but there exists no guarantee that the wateP particles will

complet-ely fill the apace oz- will exit at the establiahed

g te angle The same can be said of the exit trom the

runner blades AssUIlptiona were implied which would indishy

cate that all water particles passing a given croea section

ampH traveling at the same velocity in the same direction

the e alone are autt1c1ent to show 11m1tationa in a theoretbull

1eal approach to the problem

Assume a turbine with ordinary wicket gates tor oonbull

trol compared gainst the same turbine with a gate in the

18

draft tttbe tor supplampment1ng control or the rate ot rlow

Let it also be assumed that the two turbines are opershy

ating at the same point It 1s desirable to predict relabull

tive performance of the two turbines 1 this point of

operation is such that edd7 s hook loss ot reasonable proshy

portions is present in the fir t turbine

~ tull erteot of the shock loss will be exper1 need

by- the fir t turbine

lhe second turbine will derive certain advantages 11

the gate in the draft tube is adjusted to reduce the tlov

1n the proper amount Since they vary a the square ot

the veloo1t7bull the lossabull in the aeroll case wiomiddotket gate

and runner passages will decx-ease aetet-r1ng to Figure 2 1

it can be seen that a decreased velocity v1 w-ill reduce the

eddy shock losa

The ent loss in the dJtaft tube of the second turbine

will be the sum ot the tr1ct1onal loss and the velocity

head at ex1t The velocity head dissipated will be greater

due to the closing action or the gate but the reduoed

t~ictional loss which ia a tunction ot the rate of tlow1

will partially balance this

It 1a entirely possible that the net reduction in

losses in the second turbine will lead to a greater ettibull

oiency and more power output than 4eYeloped by the first

turbine

19

In Figure 3 the plot ot power output against turbine

speed for Curv A~ represents the typical family of curvea

tor a reaction turbine Th b st sp ed is the locus ot

points connecting maximum eft1oiency at each gate opening

The operating speed is the coZUJtant turbine apeed which

passes through the point ot maximum efC1ciencr of the turbull

bine The plot of turbine efficiency against power output

for Curve A is also ahown

It the turbine with flow regulation in the dratt tube

oan demonstrate superior power and efficiency at part loads

the effect would be the same as a shifting or the power

curves toward the condition shown fop Curve B 11 Thisbull

illustrates th ultimate case of the uperpoait1on of best

and operating speeds It will be noted that the pet-form~

of the turbine ot Ourve Bu 1a better than that of CUrve

A at part loads because of ita ability to sustain a relabull

tively high etticienoy ovel a Wider range of power output

o Reguireaegts tort Test Velitication

It is desired to deterra1ne the effect on the turbine

performance b) the addition of a gate in the dratt tube

Th step in the teit will bet

(1 To determine the power output and efficiency ot

the turbine tor wicket gate settings above and below rated

conditione for a wide range ot speed

20

CURVEAbull

TURBINE SPSBD TURBID SPEKD

POIBR OOTPOl

Figure 3 - Turbine Performance Curves

21

22

(2 peat (l) with the gate installed in the drat

tube

(3) middot Converting middot all data to a constant head compare the

powere and effioiencies at the same wicket gate setting and

turbin speed tor the two cbullses

If the ddition or the gate indicates an improvement

in power output and efficiency and the powe~ curve shifts

to the right along the turbine apeed scale the advantage

ot draft tube con~ol of the flow will hav been demonshy

strated

Chapter IV

A E9J11pment

ih turbine used in this test is lJ 5 1nch Pelton

reaction turbine with a rated output ot 30 horsepower under

a head of 56 feet at a speed ot 720 reYolutiona per minute

Views of this turbine are hovn in Figures S and 6 The

turbine is installed on a concrete pad located over an open

channel in the Hydraulics Laboratory at Oregon State Colshy

lege The date of manufacture of this turbine was 1915

The water was delivered to the turbine from a sump

reservoir by two pumps operating 1n parallel Each pump 1a

an 8 inch Pelton double suction centrifugal pump witb a

rating of l$00 gallons per minute at a head ot 75 teet with

a speed ot 1175 revolutions per minute Tbe inlet tlange

ot tne turbine is $pprox1mately 18 feet above the center

line of the pump

A direct current generator was coupled to the turbine

to receive tne power d veloped as shown in Figures 4 and 7 The generator is a Spr gue Electrodynamometer rated at SS horsepower with a speed range of 7$0 to l$00 revolut1one

per minute The classification is type LO 26A 2)0 volta

Figure 5 - View of Test Turbine

Figure 6 ~ View of Test Turbine

and 149 amperes lbe generator ti ld was aepar tely

excited using direct current from a motor g n r tor ampt

(l$ p 4~8)

The power output of the generator waa dissipated in

the water rheostat (3 p 488-489) shown in Figures 9 and

10 The galvanized tank contain d water ot variable d pth

on an electrode ot cast iron m aauring 1bull x 1 x 1

In the initial installation of the turbine it was

intended that the power output should be measured with a

Prony brak bull For th purpoa68 or this teat it was decided

that the brake was too instable and the generator was

substituted The platform for raising the generator the

nee asary two teet for alignment was built out of available

material In this case heavy laminated wood blocks reiashy

torced with other timbers were used and bolted through the

concrete deck (11 Pbull 36-$7)

Due to the light concrete deck the lack ot mas in

the platform and the slight misalignment in the flexible

coupling ao e vibration waa encountered It seemed to

ncr aae linearly to a maximum at the speed of bout 750

revolutions per minute Above this speed no vibPation was

noticeable The vibration waa not se~ere and does not

appear to have materially affected the test results

26

B Intrumentat1on ~ eaeur1ng Devices

The pressure head at inlet to the turbine vaa meaave4

bymeane ot two )6 inch waterbullmeroury manometerbull connected

in series as shown in Figure 8

The terminal voltage ot the generator vas meaeured by

a laboratory voltDleter with a range to )00 yolta and callbull

brated to within 15 Yolta

The armature current bull and hence the line current was

measured by a laboratory ammeter with a range to 150 amperea

and callbrated to w1 thin o 7S amperes

Tae rate ot tlow was established by weight and time

meaeurementa The weighing ank has a capacity ot 121 000

poundsJ the weight belng indicated by Toledo direct reading

scales Timing was done with a hand atop watch with clivibull

aion ot 02 second

he ~ater level in the tailrace was dete~1ned by a

hook gauge lhie was read to the nearest 001 toot

The turbine and generator speeds were eaaured by a

hand tachometer The technique of almost cont1nuoua readbull

ings of the speed gave an error ot no more than 5 revolubull

tiona per minute

c Operational Procedure

Atter the water level in the aump was checked to

insure an adequate auppl7 the puapa were primed and

27

Figure 7 - Test Generator and Plattorm

Figure middot8- Instrument Board and Field Rheostat

28

started After venting they were valved for operation 1n

parallel

The motor generator set was started to supply the

field current and the circuit breaker was closed Water

wa added to the water rheostat to the level shown in

Figure 10 ~ field current wae minimized by cutting in

all the f ield resistance in the field rheostat of Figure 8

The l2 inch gate valve shown in Figures 5 and 6 waa

slowly opened and the turbine and generator brought up to

speed The 12 inch gat valve and turbine were vented and

the pumps were checked to insure neither had lost ita prime

lhe water rheostat offers very steady load 1f the

water level is essentially constant and the water temperabull

ture 1a fixed () p 488~89) In order to maintain this

constant temperature it was decided not to circulate the

water in the rheostat but rather to allow the water to

boil thua achieving the desired result A standing wave

was set up on the face ot the electrode by the boiling

action but a atable load was eatablished except at very

low water leYels where th11 agitation led to fluctuationa

in the line current

After putting the turbine and generator on the line

maximum power was dissipated in the rheostat by redueing

the turbine speed to between oSO and Soo revolutions per

minute Salt vas added to the rheoetat wat r to increasemiddot

29

Figure 9 - View of Water Rheostat

Figure 10 - View of Water Rheostat

Separate Field ExcitationFrom Motor-Generator set Compound Water-Mercury

---shy

re Manometer

I Q)

~ 0

~

Book Gauge

Open Channel

I

Slap Reservoir

Figure 11 - Wat~r Flow Diagram and Electrical Layout

31

waiting pe~iod ot perhaps an h~ followed

while the boiling point or the water wbulls reacbe4 During

this ti+ne the manometer was vented end eheoked electrical

measur1ng 1nstlUments were connected end the hook gauge was

adjusted tor elevation

It required about two- houtte tor the generator to reach

its normal operating tempe-ratu~e_ After the water in the

rheostat and generator had reached their operating temperabull

turea it was possible to begin the taking of data

The only vaPiable which was controlled wee the turbineshy

generator speed However the upper l1ut1t of safe line

current was slightly over 100 ampJilPampPes and the eireuit

breaker would open when the current reached lOS ~ere bull

Control was exercised by means ot regulating the water

level and salt 1n the water rheo tat and the res1stsnoe of

the tield rheost t~

The etfeet ot each type ot regulation on the three

variables is shown below

Volta Aaperebull Speed

Inc Dec Inc Dee~ Inc Dec

Wa~e1 Level Inc Dec~ X

X X X X

X

Salt Concentration

Inc Dec X

X X X X

X

field Resistance

Inc Dec

X X

X X

X X

32

Jlot all methods gave the ame amount ot change in a

given variable and a period of experiment and trial led to

the following scheme starting the rune with the lowest

turbine speed the water level was high with a high amount

ot salt and the field resistance was cut completely out

Aa it became necessary to increase the speed tor each

aucceasive run either cutting in t he field resistance

decreasing the salt concentration or lowering the Vater

level would produce the desired result However decreasbull

1ng the salt concentration had to be done Without a net

gain in water which led to a tluahing procedure that was

not particularly good because cold water was introduced

which required time to heat to the boiling point Cutting

1n additional field resistance was a good method but th1a

increased the amperage possibly to the point of opening

the circuit breaker Lowering the water level was aatiashy

factol1 until the level got too low causing the current

fluctuation previously mentioned Actually it turned out

that a combination of lowering the water level and cutting

field resistance in would carry the speed from ita minimum

to 1ts maximum value it the proper choice were made each

time the speed waa to be changed At the conclusion of

each aet of runs at a high speed the water level would be

low and the field resistance high

33

TURBINE

PAD AND DECK

TAILRACE

WATER SURFACamp

CONCRETE

DRAFT TU1B INSERTS

7 5( DRAFr TUBE

FLltJI ARIA

5~ DRAFT TUBE

FLOI ARSA

Figure 12 - Sketch of Draft Tube and Test Inserts

34

Figure 13 - View of Draft Tube Insert

Figure 14 - View of Draft Tube Insert

D c __ ~s_middot hedu_le of

A number was assigned to each run The fi~st number

applies to the draft tube tlow areas

1 bull 100~ flow area or 0~ oonatriction

2 - 7S tlow area or 2$ conatr1ct1on

3 SoC flow area or so~ constriction

The second number refers to the wicket gate openings

9 over gate opening

6 bull intermediate gate opening

4 bull one h lt gate opening

The third number 14entif1ea the location of the particular

1Wl in a set ot rona made at a given dratt tube tlow area

and wicket gate opening

fnua run number 1bull4bull10 would identity this as the

tenth run ot a set made at halt gate with 75 ot the draft

tube t1ow area

Rune w re made tor a g1yen dratt tube condition

Firat tor tull 41-aft tube flow area seta ot rune were

made for the overgate halt gate and intermediate gate

conditione An insert was placed in t he draft tube and

rune based on the same gate conditions were made tor the

7S~ draft tube flow area case The insert was then changed

to allow only $~ draft tube flow area

The inserts are sketched 1n Figure 12 and photographed

ln Flgurea 13 and 14 They oonaisted of circula~ segments

36

or l2 ineh plywood mount 4 on wooden legs 10 inches high

The 1nse7te were placed in position and secured by th use

ot a-clamps on the legs and the outside ot the bottom of

the draft tube The obvious disadvantage to this method

waa the neoeasity tor draining the water from the tailrace

tor a change ot 1naert The advantage vas of course the

simplicity ot design and construction

Chapter V

DATA-A Original Data

The normal data-taking crew consisted or two men

Assuming adjustments having been made to secure a certain

turbine speed (aee section on Operational Procedure) one

man would take semi-continuous speed readings with the hand

tachometer until a state or rotational equilibrium was

reached This could be only a period or two minutes up to

ten or tifteen minutes As soon as steady speed was

assured the data taking would begin The second man went

to the weighing tank Where a minimum ot three weighingamp

were made The requirement was to get three consecutive

readings such that the ditterence between tbe smallest and

largest time did not exceed 04 seconds The time to

collect a given weight ot water was then assumed to be the

arithmetic average of the three times He then went to the

hook gauge determined the hook elevation and then

recorded the data on the data sheets The first man meanshy

while had taken readings of the line voltage line current

and manometers and checked the turbine speed by multiple

readings During the length of the run all values were

38

checked to determine mean values for recording

The minimum length of one run was about five minutes

If one or more measure ants tended to drift during the run

all values wer discarded and a new run began as soon aa

qu111br1um was stabl1shedo

B -0-al_e_u_l_a_t--d Data

The h d on the tu~bine 1 defined by

($)

The maxtmwm velocity V4 was equal to about o8 tampet per

secon4 which makes it a negligible quantity when converted

into velocity head

An engineerbulla level was used to deterine the d1ffePshy

ence 1n elevation between the compound water-mercury manoshy

meter and the hook gauge Using this value the equation

for turbine bead becomes

where z4 is the hook gauge reading

The rate of flow 1 cent

w weight or water collected average time to collect

The inlet velocity v1 vas calculated by dividing the

weight rate or flow by the specific weight of water and the

)9

area ot ~e inlet pipe This was equivalent to dividing

the weight rate of flow by 490 Then the power input to the turbine is equal to

WHpin rri

10 (6)

Also

(P ~ut) Turbine

(P out) + Generator

(P lost) Generator

The power output of the generator is simplJ the

produot ot the terminal voltage and the armature (line)

curPent The power lost in the generator can be subdivided

into copper losses and stray power losses lo evaluate

these cunes based on losses of an identical generator

11leampsured by the Department ot Mechanical Engineering were

used The loss curves are reppoduced in part in Figures

15 and 16

Determination ot generator losses proceeds as tollowau

(1) From Figure 15 detem1ne the vo1tage drop in the

armature circuit using the temperatures of 1220 F and the

meaaured current

(2) The induced voltage is t~e sum of the terminal

voltage and the voltage drop 1n the armature circuit

() Entering the induced voltage and the turbine speed

into Figure 16 the stray power loss can be determined

(4) The copper lose can be evaluated from Figure 1$

using the measured current and the temperatlll-e of 1220 P

40

25 ~------~--------~--------~------~

U) -U) - 20

f-4 ~

-~ -gt 0

0

VOLTAGE DROP

~ - i -

- bullbullbull bull - -middot-middot -+ ~- + -t--+ ~ - ~ middotbull ~-~ middott- -+----- _ -4 middotmiddot- --~-+-t---r~~ ~--+t-t- - ---t-c-++~-ulf--

0 50 75 100

Figure 15 - Curves of Generator Voltage Drop and Copper Loss

41

1200

1000

800

600

800

0

0

~-

middot--~ 1shy --1 + bull l

100

I -

150 200

IIDOOED VOLTAGB (VOLTS)

Figure 16 - Curves of Generator Stray Power Loss

_ j

-bullshy -L---- shy middot -shy

250

- r

42

(5) The generator los os equal the sum of the eopp r

loss and stray power loss

~e efficiency or the turbine is taken as

etticiency u e =P out (8)Pin

~ample pound Determ1n1gg turbine Power Output

The following data are taken trom that ot Run 1-9-1

Line voltage 1040 volts Line current 870 amperesSpeed 355 revolutions per minute

The induced voltage 1a determined as follows

Line voltage 1040

Voltage drop 90 using Figure 15 with line current of 870 amperes and temperature ot 122 degrees)

Induced Toltage 1130 volta

The power output of the turbine is determined as follows

Generator output 90$0 (line voltage z line current)

Oopper loss 7 (using Figure 15 with line current of 870 amperes and temperatUe or 122 degrees)

Stray power lose 470 (using Figure 16 with speed ot 355 revolutions per miDUte and induced voltage or 1130 volts)

Turbine power output 9527 vatta

or turbine power output 1s 12z2 horsepower

43

The conversion of the calculated data to a constant

head is based on the conventional assumption of constant

efficiency regardless of turbine head For a constant head

ot 81 teet a purely arbitrary figure the tollowing relashy

tionships are ass1lJiled to be true

I ____L (9) (i)l72

(10)

For these two values the specific a peed may be combull

putedt

N t Jt VPt (11)8 243

Chapter VI

~RESULTS

A -Pr_e_ae_n_t_a_t_t_o~n g Reaultbull

Graphical presentation ot the results ot this te1t

are given as follows

Figure 17 -Turbine characteristics with 100~ dratt

tuba 1low area

Figure 18 - Turbine characteristics with 7S dratt

tube tlow area

Figure 19 bull Comparison ot power and etticiency at

over gate conditions between 100 and

75~ draft tube flow area

Figure 20 bull COZQparison of power and ettic1ency at

halt gate conditions between 100~ and

7S~ draft tube flow area

Figure 21 bull Comparison of power and etticiency at

over gate condition between 100~ and

So dratt tube tlow area

Figure 22 - Comparison in variation ot apec1t1c

speed between 100 and 75~ dratt tube

tlow area

50

45

20

-bull - 1--shy40

bull J-~ 30

~ ex

~ 20

~~ ~ -)q

I

~ - _

- -

10~ OF DRAFT TUBE FL(Jif AREA

CONSTANT HEAD OF 8l FEST10

POIER OUTPUT EFFICIENCY SPECIFIC SPEED

0 ~--------------_--------~------~------~ 400 600 800 1000 1200 1400

TURBINE SPEED (RPM)

Figure 17 - Turbine Char~cteristics with 100 Draft Tube Flow Area

50

46

-bulllle

~ 7 ~ OF DRAFt TUBE FLOW AREA

0 -~~-rl C05STAMT BEAD OF 81 mET 1J~

POIER OOTPUT ---+- ---o ~_H EFFICIDCY ~ I shy

bull ql SPECIFIC SPEKD - ~ -

bull ~ J 10 L rmiddotr- r- -

bullz- I

~~ 30 ~~--~----~~-

20 ~ ~ middot-shy

26

~~ 25

~0 ~r-----i (

Tbull -bullshy

400 600 800 1000 1200 1400

TURBINE SPEED (R PK )

Figure 18 -Turbine Characteristics with 75 Draft Tube Flow Area

47

EFFICIENCY 60

1-----shy

-~ 50~--~--~~-~middot middot middot middot r~-~----~~~~---4~-r~-~~gtt

II

POWER~ J ~ bull bull

u I

sH

40~------+-------+---- -~~--~~-~~~~

~----~rl 1 bull

I

I

0~--------------~------_------~--------

~ -OVER GATE CONDITION

COIJSTANT HEAD OF 81 FEET

0 o 10~ DRAFt TUBE

_-- _ 7~ DRAFT TUBamp FLON AREA II

10_~-----+--------r-------r----~~

400 600 800 1000 1200 1400

TURBINE SPEED (RPM)

Figure 19 middot - Comparison between 75 and 100 Draft Tube Flow Areas of Power and Efficiency at Over Gate Conshydition

48

t

bull --4 r ~- ~ middot~

70 1-----------+-~~~~~+middot ~ ~~ middot middot -~~--~~--------~~----~-+1

-~-

Atbull bull

lla-

60

amp0

40

20

10

oampOO

t _ - - ~-+- - -~-

l2 GATB COJIDITIOJJ

COJISTABT HJW) OF 81 JBET

o 0 lOQ( DRAFl TUB8 FLOI AREA

e-- - e 75 DRAFT TUBE FLOW AREA

800 1000

- r-

~

TURBIbull SPBIID (RPII)

Figure 20 - Comparison between 75 and 100 Draft Tube Flow Areas of Power and Efficiency at Half Gate Conshydition

49

60

50

-40

bull 30

IIQbull

20

10

0

400

- t - ~

EFFICIENCY

_J bull - bull bull

~ r r middot t -+ shy L -t -

OVER GAD COliDITIOI

CONSTABT BEAD OF 8l FBB

o o 10~ DRAFt TUBE FLOI ADA middot--- 5~ DRAF TUBE FLQPi AREA

600 800 1000 1200

Figure 21 -Comparison between 50~ and 100~ Draft Tube Flow Areas of Power and Efficiency at Ove~ Gate Conshydition

50

25

20

15

10

0

Figure 22

~- T -4 -t- -l --~-

t-~ I

middot --~- t ~---- _ __ _ + --

----~- --r-- --

~-=J-~-=-~ -==~ _ ~- -- ---f---1 - shy

CONSTANT HEAD OF 81 FEBT

o--o 1~ DRAFT TUBE FLltll AREA

75C DRMT TUBK FLCIJ AREAmiddot--middot-middot 600 800 1000

TURBINE SPEED (RPK)

Comparison of Specific Speeds for 75 and 100 Draft Tube Flow Areas

51

B Discussion 2 Result

Consideration of Figures 17 and 18 indicates the

overall eftioi ncy pattern or hill is significantly or

rounded for the 7$~ flow area than for the 100~ flow area

bia implies a greateP efficiency is possible at speeds

leas than or greater than design speed with an insert in

the draft tube However the muilDum efficiency is lemiddotas

Direct comparison at over gate conditions is made in

Figure 19 ~e same general trend is noted tor both the

etticiency and power curves for the 7$~ flow area case

The eurves show higher values at overspeed than do the

correaponding cWvea for the 100 flow area case It ia

not clear whether the curves have been shifted by the dratt

tube constriction or whether the curves simply bulge past

the normal curves at both overspeed and underspeed condishy

tions The power curves apparently peak near the aeme

point bullalthough maximum power is still obtained with the

normal draft tube area

For the comparison at halt gate operation shown in

Figure 20 a general improvement has apparently been made

by restriction of the draft tube flow area At every speed

the etticienoy and the power is greater for the restricted

tlow case The two ett1o1ency curves and two power curvea

are practically parallel throughout the speed range ot

teat

As the flou aroa i e decreased still farther a s1gn1

ticant change appears Reterr1ng to Figllle 211 tor the $0

flow area curves it a obvious that exit losses have

become excessive at the overgate condition because the

efficiency and power are everywhere leas than tor the case

of normal draf t tube area

Earlier it was pointed out t hat 1t the r esult s 1nd1bull

eated an increase in both power and ef tieiency- t hen it

could be assumed tha t the additional los s i ntroduced with

the draft tube insert is less than the diminished losses

due to leas shock losa and water passage losses For the

places where both the efficiency and power have been

increased we can assume that the insert has improved turshy

bine performance

For the places where the power haa been decreased

nothing can be said as to the elimination of ampbock loss

because the new lose present with the drat tube insert has

overshadowed any gains in eftecti Ve head upatJ-eam of the

insert

Near the peak of the efficiency hill howeve~ it may

be pointed out t hat shock loaa ie a minimum with a normal

draft tube and the insert merely adds an additional loss

with the resultant decrease in maximum efficiency tor the

7$~ flow area case

Perhaps the most s1gn1ticant set of eurves is shown aa

53

Figure 22 In this graph values of specific speed tor the

75 and 100~ flow area cases for both over gate and one

halt gate openings are plotted against turbine speed At

every speed and both gate openings the value ot specific

speed for th 75~ flow area case is greater than that for

the 100 t1ow area ease

Since the head is a constant for both situations this

may be interpreted in either of two ways trom equation

(11)

(1) For the same turbine apeed restriction of the

draft tube t1ow area resulted in greater turbine power

(2) For the same power amputput the turbine with 75~

draft tube flow area operated at a greater speed than did

the one with 100 flow area

Since the required diameter of a turbine varies

inversely with the speed the second interpretation could

be stated such that a smaller turbine could be used to

develop the same power output

Whether viewed trom the aspect of increased power

greater speed or reduced size the performance of the turshy

bine with reduced draft tube flow area is superior to that

with the nolmal flow are in the draft tube

The curve of specmiddotific speed versus turbine speed for

the so draft tube flow area case at over gate cond1t1ona

was not included in Figure 22 This curve lies below that

for the 100~ flow area c se at all speeds

In elaboration ot the second interpretation of Figure

22 attention is directed to the relative magnitudes ot

increased apee1f1c speed tor the two gate openings Assumbull

ing that the increase in specific speed implies a shift ot

the power curve to the right along the turbine speed scale

the power curve would be shifted more tor tbe halt gate

opening than tor the over gate opening

It thia trend could be extrapolated to the other gate

openings the tendency can be seen tor the line ot beat

speed to rotate toward the line of the operating speed as

illustrated in FigtU-e ) The advantage of this has already

been discussed

This particular turbine has a low specific speed tor a

reaction turbine Aa the rated value of apecitic apeed tor

reaction turbines increases the line ot beat speed departs

even more radically from the line of operating bullpeed It a

test similar to this were conducted on a reaction turbine

ot gleater specific speed it is pJobable t hat the rotation

ot the line of beat apeed would become more p~onounced

The scheme used in th1a teat had two obvious dr wbull

backs The first was the decision to leave all the wicket

gamiddottes installed tor all conditions ot the draft tube

These gates predominated in control of the tlow The

inserts added to the draft tube merely acted as auxiliary

55

contrGla

The aecond drawback was the choice or device to place

in the draft tube The reasons foll selection of this type

of device have been previously mentioned It is to be

anticipated that adaptation ot dratt tube flow control

would result 1n a better device for an actual turbine

installation Such apparatus might take the form of a

pneumatic bladder or a h7drau11oally operated variable

venturi section in the draft tube It is conceivable that

the gate as used in this test might be adapted also

Chapter VII

OONCLtJSIOfS

From the results of this test the following eonolubull

e1ona aa to the effect ot a variable draft tube flow area

on the performance or a r action turbine may be drawn

(1) The effect ot a variable draft tube tlow area 1a

generally favorable upon the operat1Gn ot a reaction turbull

bine because or the tendency tor the line or beat speed to

rotate toward the line ot operation This resulte in

better performance of the turbine at partbullloads

(2) he etf1o1ency eh111 tor the turbine beeomaa JDore

tlat at the top leading to a smaller max1JilWD effic1enc7

but e reater etticieney at other pointe of operation with

the insertion ot an auxiliary control ror the rate ot tlov

in the draft tube

(3) The power output of the turbine will increase at

over speed over gate conditione as well a at part gate

conditions with the proper amount or draft tube eonatr1cbull

tion or flow

(4) It is possible to eliminate at least partially

eddy type shock loss by tho introduction ot flow control

in the draft tube

BIBLIOGRAPBl

1 Addison Herbert A treatise on applied h-draul1cs New York Wiley 1954 724 Pbull

2 Allen o M and I A Winter middot Co111parative testa on experimental draft tubes Tranaact1ons ot the American ociety ot Civil Engineers 87t893bull970 1924

3 Barrows a E Water power engineering 3d ed ew York McGraw-Bill 1943 791 Pbull

Bovet G A Modern trenda in hydraulic turbine design4middot in Europe Tranaactions of the American Society ot Mechanical Engineera 75975bull993 1953bull

s Oreager William P and Joel D Justin Hydroelectrichandbook 2d ed New York Wiley 19$0 1151 Pbull

6 Daily Jamea w Hydraulic machinery Int Hunter Rouses Engineering hydraulics Hew York Wiley 19$0 p 8$8bull99

Daughertybull Robert L Bydraulie turbines ew Yorkbull7middot MoGrav-Hlll 1920 281 Pbull

8 Daugherty Robert L Inveat1gat1on of tne performance ot a reaction turbine ~anaactiona or the American Society ot Civil Engineers 7811270bull1304 1915

9 Davie L M Model and prototype testa Int Trend in hydraulle turbine practice symposium lranaactions ot the American Society ot Civil Engineers 1o63S3middot368 1941

lfJ Doland James J Hydro power engineering Hew Yorkbull Ronald 1954 209 Pbull

11 Gandy Theodore s and Elmer c Schacht Direct curshyrent motor and generator troubles operation and repair New York McGraw-Bill 1911 293 Pbull

12 Gibaon Arnold H Hydraulics and ita applications5th ed London Constable 1952 813 Pbull

58

13 Button s P Component loases in Kaplan turbinebull and The prediction of efficiency from model tests Probull coedings of the Institution or Mechanical Engineers168743-762 1954

14 Knapp R T~ Oavit t1on mechanics and its relation to the d sign or hydraulic equip ent Proceedings or tne Institution ot Mechanical Engineers 166150bull16) 1952

15 Langsdorf Alexander s Principles of direct curHnt mach1nee 5th ed New York r~cGrawbullH1ll 1940 746 Pbull

16 Lsrner Chester w Characteristica of modern hydraubull lie turbines Trans e~ions of the ~~erican Society ot Civil Engineers 66306-386 1910

17 Linsley Ray K Jr and Jobulleph B Franzin1 Eleshyments of hydraulic enginebullring New York McGrawshyBill 19$5 $82 Pbull

18 Mead Daniel w Hydraulic machinery llev York McGraw-Hill 1933 396 Pbull

19 ead Daniel w Water power engineering New York McGrawbullRill 191S 843 Pbull

20 Mockmore Charles A Part gate operation at water turbines Corvallis Oregon State College Department ot Civil Engineering 1933 11 numb leaves (Unpubshylshed typescript)

21 Mockmore Oharles A Flow characteristics in elbow dratt tubes Transactions of the Amez-ican Society ot Civil Engineers 103402middot464bull 1938

22 Moody L F Hydraulic machinery In c v Davis Handbook ot applied hydraulics New York McGrawshyHlll 1942 1082 Pbull

2) Ptau At-nold Hydrbullulie turbine handbook ld ed Milwaukee AllisbullOhalmers ManufactUIing Company 1948 70 Pbull

RheingalUI w J Recent developments in Francis turshybines Mechanical Engineering 74189-196 1952

25 Russell George E Hydraulica 5th ed New York Henry Holt 1942 466 Pbull

26 Safford A and E P- Hamilton American mixed tlow turbine and ita setting Tranampactions or the Amerieal Society of Civil Engineers 851237bull1)56 1922

27 bull Spannhake W1lhe1Dh Problems or modern pump and tur b1ne design Transactions of the American Society of Mechanical Engineers 56e22$-248 1934bull

28 Sutherlandraquo R A Better ethod or representing and middot tudying water turbine performance ~ansaetions ot thmiddote American Society of Mechanical Engineers 68t675bull 686 1946

29 Teats ot five models or draft tubes tor turbines Engineering News-Record Pbull 182-184 Aug 2 1923

30 White w M American hydztaulic turbines Mechanical Engineering S2t390bull39S 1930bull

31 White w M lhe hydraucGne rega1ner1 its developmentand appl1eat1ons 1n hydroelectric plants Meohanlobulll Engineering 43t37Sbull380 1921 middot

32 Winter I A Economic principlebull in designbull Int Trend in hydraulic urbin practice bull a ampoeiumTranaaot1ona ot the American Society ot Civil Engineerslo6332bull3S2 1941

33 Wiel1cenua G F Fluid mechan1ca or turbo-machineryNev York McGraw-Hill 1947 613 Pbull

APPENDICES

c

Appendix A

NOATIOB

A Angle between the absolute velocity vector and the tangent to the rwmer Subscripts 1 and 2 refel to entrance and exit ot the runner blade

B Angle between the relative 1elooity vector and the tangent to the rwmer Subscripta 1 and 2 refer to entrance and ezit or the runner blade

Angle between the tangent to the runner blade tip and the tangent to the runnel- Subscripts 1 and 2 reter to entrance and exit of the rt1rmer bladebull

Blade angle-gate opening conetant defined by equation (1)

e 09erall efficiency

g Gravitational acceleration assumed constant at 322 teet per second per second bull

H Turbine head detined by equation ($)

m Exit loss coeft1e1ent

Turbine speed expressed in revolutions per minute

Turbine speed under a constant head of 81 teet

specitic apeed of the turbine under a constant head ot 81 teet

p Power output in horsepower ot the tvbine

Power output of the turbine Ulder a constant head ot Sl teet

Pl- Pressure head at entrance to the tUlb1new

l1 Peripheral velocity ot the runneP Subacr1pta 1 and 2 refer to entrance and exit ot the JUnllampr blade

62

v Relative velocity reaulting trom the combination ot the absolute water velocity V and the runner periphshyeral velocity u Subscripts 1 and 2 refer to entrance and exit ot the runner blade

v] Relative velocity vector necessary to produce a tanbull gential entry into the runner blades

V Absolute water velocity Subscripts l and 2 refer to entrano and exit ot the runner blade

v2 Velocity head Subscripts 1 and 4 reter to the ~8 entrance to the turbine and the tail~ace wate~

w Unit weight ot water assumed constant at 624 pounda per cubic toot

V Weight rate ot flow in pounds per aeooncl

XX Velocity component ot ahook See Figule 2

Z Elevation head Subscripts 1 and 4 reter to entrance to the turbine and the taibace water surfacebull

Appendix B ORIGINAL DATA-Run

lfwnber

0-4-1 0-4-2 0-4-3 o-4-4 o-4-S o-4-6 0-4-7 0-4-8 0-4-9o-4-lo o-4-11 o-4-12 0-4-13

o-6-1 o-6-2 06-3 o-6-4o-6middotS o-6-6 o-6-7 o-6-8 0-6-9 o--6-lo o-6-11

Speed

rmiddot2middotbullmiddot(1)

336 38$ 451 S$9 620 669 6lt)$ 120 787 860 932

102imiddot109 bull

352 355 443middot 543middot 620 654AJs32

911 1001 1111

~essure Head rt (2)

410 410 416 426 431 43-7 439 44-9 452 467 482 soo $1 bull $

350 351 35middot7 )66 37-9 37-9 392 41 bull 3 43middot3 460 489

Elevation Bead

fjj $7 $7 $7 $7 $7 $7 51 57 5-15858 $8 58 56 56 $6565656 51 575As5a

Velocit Head

flj 07 07 07 06 06 06 06 os 05 os0404 03

09 09 oa o8 o8 os 07 07 06 o~o

Total Head rt ($)

47middot4 4A44 o 489 49-4 soo $02 $11 $14 $29 5imiddot45 2 576

41 bull $ 416 421 430 44middot3 44middot3 456 47-7 496 523551

Plow

lbtjec

326 324middot317 311 306 30029middot28 middotmiddot middot 386 275middot260 240 218

359 36~35 bull 349 345middot 339 330 318 300 273 240

Line Potential

vyqjbull 1060 1220 ~-0o 1920 2150 2000 2$60 2000 1940 18)015io11 o

1000 1100 139bull5 1760 1925 16$0 1620 1610 1540 1330 870

Line Current

amlscs 960 900 830 740 730655 70bull 0 530 660 600 5imiddot54 6 )60

982 930 860 780 ~3-545

79-5 74-5 670 560 370

P

Appendix B ORIGINAL DATA (Continued)

Run Number

Speed

Pbulltmiddotbullmiddot )

leasure Head ft(2

Elevation Head tt(J)

Velocity He-dfmiddotj

Total Bead tt($

Flow

lbstsec( )

Line Potential vo~ta( )

Line Current

amjs (sect

0bulllt)-1 0-9-2

3ll6 398

28o ~~1

$6 56

1o 10

346 347

390 365

1ooo 1190

aao 835

0-9-3 0-9-4 o-9-S

472 565 632

292 305 312

$6 s6 56

10 o9 o9

)$8 J7~o 37~7

381376 37o

1)6614oo 141o

820 ass ass o-9-6 0-9-7 0-9-8 o-9-9 0middot9-10

680 120 762 844 920

)24337346 366 390

56 $6 56 57 $7

09 os o8 oa 07

)89401 410 431454

367~ 357348 34o 322

1400 1J6o l36o 1310 1170

843 820 7957So 67~0

0-9-ll 0-912

1001 1100

41 bull 7 45-3

s 7 6~0

06 os 480 $18

299 268

980 65$

560 36~5

1-4-1 1-4-21-4-l1-4shy1-4-5 1-4-6 l-4-7 1 4-8 1-4-9 1-4-10 1middot4-ll 1-4bull12

354middot452 562 62q 674shy102 752 760- 863 932

1022 1100-

)82389 4014oa 416 41--7 423 428 44-2 45-7 486 49-2

51S757 51 5-7 5middot15zs sa $8 58 59

07 07 06 06 06 06 06 os o bull o 04 o J

446 45-)46middot4 471 ti7-9480 q86 491505 $19 548 55-4

)28 320 311 306 300 295 291 286 269 2582iimiddot21 bull

1080 14Lo 1550 153-5 1470 141-0 1385 1310 1310 1230 1120 855

970855 875 91-0 94~0 975 966 995 860 77-S 610 4fo

0 ~

Appendix B ORIGINAL DATA (Contirmed)-Run Speed Pressure Elevation Velocity Total Flow Line Line

Number Head Head Head had Potential Current rtjjmbull t~ bttec vyfs am~a12) ( ) ti fli 8

1-6-l $6 33$ $6 0bull9 400 364 1100 93 0 1-6-2 41 34laquo2 $6 oa 406 JS7middot iios a5s l-6-3 500 3~0 5bull6 os 356 1 1 o aos 41middot~1-6~4 35bull4 5-6 oa 41middot 352 16~0 82 0 5~1-6-5 5 bull 36_2 Sbull6 08 42bull6 349middot 161 ~ 0 86~0 1-6-6 622 366 $6 oe 43bull0 345middot 158 0 88~$ 16-A 649bull 37bull1 56 os 43-S 342middot 1570 895 1~- 386 57 07 46-0 192 ) 125A44 333middot 1-6-9 3) 404 5middot1 07 468 317 1620 675 1610 911 42-4 5-7 o6 48-7 298 168 0 61 0 1-6-11 999 451 56 os Sl ll 276 ~2-0 530 1-612 1115 485 58 04 54middot7 238 90 )3 0

1middot9-l 355 279 56 10 )45 385 1040 870 1-9-2 399 28J $6 10 )49 38$ 1140 86 5 l-9-3 ~ ao 291 56 ~0 35middot1 J8J_ JJ6o 815 1bull9-4 579 303 56 09 )68 375middot J4JO 830 l-9bullS 40- 313 )6 09 31middot8 370- 1460 82~0 1-9bull6 679 2) 56 09 3 bull8 364middot 1670 710 l-9-7 682 319 56 o9 384 ) 62 1460 79 5 l-9-8 724 33middot5 56 o8 399 3$6 bull 1480 76 -5 1-9-9 762 34middot3 $6 0 bull 8 407 )48 14910 13middotS 1-9-10 833middot )60 5middot7 os 42$ 339 144$ 686 1-9-ll 926 39middot1 5-7 07 455 318 1290 600 1-9-12 1000 41middot3 0-6 476 298 1115 510$ ~ 1middot9-13 1105 452 s o4 $14 2$6 710 )10

~

Appendix Bt ORIGDIAL J (Continued)

Run Speed Pressure Elevation Velocity Total Plow Line Line Number Head ltead Head jlamp$d P()ten~ibulll Current

r~~~m ft ft lbs~seo voltattj rgj twimiddot t 1 t2gt lt3 ou t ( rt

2-9-1 384 289 S 6 10 35 5 1400 1170 810 2-9-2 443middot 29$ $6 ltimiddot9 360 379middot 11(0 87$ 2-9-J 536 30bull 3 sc 09 )68 374middot 1)40 84 bull) 2-9-4 571 306 $6 09 3~1 372 120bull 0 955 2-9-5 623 316 S6 09 J l )6S UJSo 77$ 2bull9-6 669 327 S6 09 )92 )61 1240 905 2-9bull7 712 )39 56 os 40-3 351 12(0 86 bull0 2-9-8 ~5$~ J48 56 oa 412 348 1290 81 bull ) 2-9-9 04 )63 56 oa 42-7 339 12ltJO 76$ 2middotmiddot9-10 8$2 376 5middot1 07 440 33~- ~ o 710 2-9-11 955 394 5-1 o6 457 300 1100 506 2middot9-12 1000 421 $7 06 48middoti 295 1020 $18 2-9bull13 110~ 463 56 05 $2 267 620 3~0

oshy0

Appendix Gt CALCULATED DAgA

Turbine Run Generator Generator Turbine Turbine Efficiency Turbine Turbine Specit1c

Number OutputKWlt21

Loa~Jes KWlol

Outut K bull (H)

Input RP 12)

middot Percentlt13gt

Speed r~Jmiddot(

0ltput HP ~1

Speed r-m

( 6) middot

o-4-1 0middot4-2 0-4-3 0-4-4 0-4-5 0-4-6 O-qmiddot7o-4-8o-4-9 0-4bull10 0-4-11 o-4-12

1018 1o9a 1220 1)62J40214oa1J4oo 1357 1320 1164 997 718

046 o59 071 092 096 1071oo 134 104 100 109 107

14261sso 17)01948 2008 20322011 1999 19 09 1708 14-84 11o6

281279 27-7 276 215 273271 268 268 26h 258 24-5

soa 555 62$ 705 7)1145 742 74-6714645 51s 45-1

440 sos 585 720 195 sso sao 9$$ 985

1065 1135middot 1230

318 357 319 416 422 419412 39middot9 378 324 260 191

102 12bull4 148 191 21bull 3 22o 233 249 24924middot9 238 221

0-4middot13 418 104 699 228 306 1300 117 18)

o-6-1 982 045 1376 271 $08 496 376 124 o-6-2 o-6-3 G-6-4o-6-5 0-6-6

1023 1200 13 73 J415 139h

051 0middot66 oaa ()bull 96 088

14-39 1696 1958 2026 1986

276 27middot4 273 278 274

$20 61 8 717 7)0726

q95615745 8)5685

390 ll5middot3 sos soo 490

127 170 218 243 2$$

o-6-7 o-6-8 o-6-9o-6-lo

1288 1199 1032 7-45

o9o 094 09$ 096

1846 1733 1511 1128

274 276 271 260

67S 629559 43middot4

980 1085 1165 1245shy

436 )83316 21bull 7

266 276 270 239

0-6-11 322 1oo 566 2141 2JS 1350 101 177 0 --4

Appendix C CALCULATED DAlA ( Continued)-Run

Number Generator Generator

Out2ut Losaes xw LW- 12gt (lO)

Turbine Out2ut

ltPlJ

Turbine Inat lfP Jig)

Etpound1e1ency

PireentDl

Turbine Sed x-~m( 1

Turbine OutEut RPJl)

Turbine Specific

SeeedrIbullntbull

( 6)

o-9middot1 0-9-2 0-9-3 o-lt)-4 09-$ 0bull9-6 0-9-7 0-9-8 0-9-9 0-9-10 o-9-11 0-9-12

aao 994

111$ 1197 1206 1180 11)21081 982 784 5-49 2)9

0middot45oss o6$ 070 07$ 0-77 (l77 or~ o s06o 8 096

123~ 1402 1$80 1698 17bulllS 168$ 16bull18 ~middot5430 1151 a~J4 9

24middotgt24middot3248 25~25 260 260 259 267 266 26middot1 2S2

sos 577 63-7 671 676 650 621 60036J4

327 178

$) 610AlO 3$

92S 980

102$ 1070 1157middot 1230 1300 137Smiddot

44middot4 soo 523 ssomiddot 540so6 46-5 432 368 274 18~8

J46 176 21-1 255 2802s_A 28 289 288 265 231 168

1-4-1 1-4middot2 1-4-3 1-4-4 1-4-5 1-4-6 1-4-7 1-J-8 1-4~9 1-4-10 1-4-11 1-4-12

10bull48 1231 13-S6 1397 1)821375 1))8 1303 1127 953 683) 51

048 067 o7A07 0 bull79 oa1 oss o bullao osa 0lt)0 096 099

J468 1740 1921 1978 1958 19$1 1911 lSSi162 1)98 1045

603

266 264 262 262 261 2512$7 2$6 24middot7 24-3 233 217

551 660 13middot3155 75-6 7~-97 middot4 72$ 67 51middotJ 44middot9 21middot1

475 605 A4220

875middot 910 970_

1000 1090bull 1166 1243 1330

5816

44middot444middot5 430 427 412 392 329 273 188 l0-7

117 101 204 22$ 2)7245 2562sa 257251 222 179

a-C))

Appendix Ct CALCULATED -DATA ( Ocntinued)

1-6middot1 1023 o$2 14-41 26S 505 41~6 26~

54middot5 13middot3l-6-2 1201 067 1boo 625 47-9 17shy~middot41-6bull3 1296 oA9 1 middot43 26 9 700 so5 20bull 4 l-6-4 l3j5 o 0 19~09 268 71bull3 A5o 514 222 1-6-5 1) 5 o81 19(gt4 271 725 51-5 238 l-66 1398 081 198) 27-0 736 8 S13 252~-middot l-6j 1405 083 199i 211 733 885 $middot06 2$9 l-6 13middot9~ 103 2amp 0 279 71 8 985~ 467 ~-69 1228 1 bull 02 17-SS 270 661 109$ 407 ~3~ l-6bull10 1025 100 lSll 26i 573 1175middot 27~S32middot~l-ampu 153 1-00 llft3 26 444 1270 22 24bull8 1bull6-12 294 100 52a 231 22 3 1360 95 172

1-9bull1 904 048 1275 2J4Z $28 S4$ 459 1$2 1-92 98$ oss 13-92 24middot4 57-0 6JO 49bull1 176 1-9middot3 1110 066 1$76 24middot9 63middot4 I2o 536 21-7 l--9-4 1187 072 1685 251 66$ 5 $$ bull 0 261 1middot9-5 llltJ7 1710 25middot4 67-3 93$ 536 28~20-671middot9-6 1186 o 8 1708 25-7 67) 980 $15 2691-9- 1161 oBo 1660 2$middot3 6$6 990 508 29-1 l~- ll-32 oB) 16sect0 2$8 632 1030 471 291 1-9bull9 109$ oa5 2$7 614 1075 29S~middot 0 4imiddot41-9-10 9~91 oas 262 S$1 1150~ 3 o 292 1-9-11 o9o u57 12JiO 21gt 26-77middot74

-45 26sect ~middot91-912 $69 091 sas 25 middot3 1)0$ 196 2J-8 1-9-1) 220 098 426 2)9 178 1390middot 84 16 6

0 0

Appendx C CALCULATED DATA (Continued)

Turbine Run Generator Generator lurbine Turbine Eft1e1eney Turbine lurbine Spee1f1c

Number Output Losses Outit Input Speed Output SPed middot k_-V KW R _ H_bull_P Percent r Thm HP rpm_ (9) tlo) 11) middot (12 _) (lJI ( ) (1$ (14)

2-9-1 9--46 055 1)62 258 528 580 164 2-9-2 1024 056 248 58 4 665 4 9 191iimiddot48 4~middot0 2-9-3 1132 067 05 2$0 641 795 52q 237 2-9-4 1148 065 1027 2$1 -~8 845 525 252 2-9-5 11 77 oso 16-83 253 6 910~ 522 270 2-9 6 1122 071 1600 251 622 960 47-5 2722-9-A 1092 015 1562 257 608 1010 445 2z12bull9- 1052 079 1514 261 580 1060 41middot7 2 2 2middot9-9 986 o82 ]429 26) 542 1105 372 277 2-9-10 915 086 1340 268 500 1160 334 27-6 2-9-11 638 087 972 254 )81 1270~ 229 250 2-9-12 )28 090 828 259 )19 1295 179 226 2-9-13 192 094 383 2$ 6 150 1370 7 3 152

-3 0

Page 18: The Effect of A Variable Draft Tube Flow Area on the

11

2 shock loss (XX gt2g

C =sin (BimiddotAl)Let (1)sin Bi

(UlmiddotCV1)2Then shock loabull (2)- 2g

For a given gate opening C ia a constant ranging

from about 14 to 10 For a well designed wheel it is to middot

be expected that C would be approximately equal to U1V1

at rated conditions ie at point of maximum efficiency

This point will occur in the neighborhood of 3~ to 78

gate opening for moat turbines For overgate conditions

the angle A1 becomes larger so the value of C would

decrease For gate openings below rated conditions t he

angle A1 decreases and C would decrease One could expect

a fairly uniform decrease in t he value of C as the gate is

closed from t he overgate position

The velocity v1 is approximately constant for any

turbine speed since the area and rate of flow both decrease

fairly uniformly However for a given gate opening the

velocity V1 will decrease with increased turbine speed

From the foregoing comments and equation (2) the

following trends can be established

(1) For constant turbine speed the shook loss curve

will be close to parabolic in shape concave upward and

have its maximum near t he point of complete gate closure

--

12

and its minimum near the rated gate position

(2) For conatant gate opening the shook loss curve

will approximate a symmetrical parabola with its vertex

the point of minimum loas located at the rated condition

of operation (7 Pbull 79)

c Exit Loas

It can be seen from Figure 2 that the exit loss from

the turbine would be v222g if no draft tube were present

The addition of a draft tube permits the gradual reduction

of velocity by an increase in cross sectional area between

the exit of the runner and the exit from the draft tube

The exit loss and the frictional loss encountered in

the draft tube may be placed together in the expression

m va2 (3)Exit Loss ~---2g

For the ideal case of no friction in the draft tube

m is equal to the square of the ratio of the area at exit

from the runner to the area at exit from the draft tube

In an actual turbine installation however friction

will change the value of m (7 p 84-85) to somewhere

between that for the ideal case and a maximum ot 10

In the interest of maintaining a minimum exit loss

the turbine should be designed and operated so the velocity

V2 will be minimum This will occur when the discharge

13

vector is at right angles to the tangent to the runnerbull

ie the angle A2 1e ninety degree bull It ia to be expected

that this condition will be tultilled near the design con~

d1t1ons ot the ~bine

Current design praetiee 1 to have a small component

ot v2 in th$ direction of turbine rotation at rated condibull

tion$ ltS p 938)

For a constant turbine speed the d1seharg or exit

loss is ess nti lly a constant

For a constant gate opening the exit lo s curve is

aptrroximately a symmetrical pa~abola with ita vert x the

point or minimum loss located at a slightly lowe~ speed

th n the turbine rated speed (7 Pbull 79)

Chapter III

PROPOSAL OP ALlERMAlE MFTBO 0 CO TROL-A lz ~ Location 2 Control

Thua tar only practice and theoretical aspects appemiddotrbull

taining to present day turbinea have been d1acuaaed It

haa been presented that control over the ~bine ia ezerbull

oiaed b y manipulation of the wicket gatea located 11101led1bull

ately preceding the runner These gate - upon rotation

modify both the magn1tu4e and the direction ot the entering

velocit7 Moreover it has be n shown that a simultaneous

change in these two variables leads to inefficient operabull

tion by the introduction of shock loss he farther the

point of operation a from the rated conditione the more

aerioua ia the ahock loss encountered

Any attempt to better turbine pertorance at other

than rated conditione and tbne flatten the top ot the

etticieney hill8 must concentrate upon the lessening ot

the ahock loaa It 1a a aumed that 1 provement in the

scroll case gates and runners would lequ1re sueh pertecbull

tion 1n machine work and metal$ as to be prohibitively

expensive

It ie surmised that any move to elblinate eYen parbull

tially the shock loss would require separate control ovel

l$

the flow and gate exit angle Since it is improbable that

d1~ect1on could be controlled at any location other than

where the gatea are situated in current turbines it will

be assumed that guide vanes will be necessary regardlesa or the method used to control the rate of flow

The primary purpose ot th se guide vanes 1s that or control over the direction ot the incoming water They

should be free to rotate in much the same manner as ordibull

nary wicket gates in order to exercise control over th

turbine speed

If the rate ot tlov is to be controlled elsewhere it

must be modified either in the penstock or the draft tube

Devices that could be used are standard valves gates

variable orifices variable venturi sections and associated

flow regulating schemes

Alauming it were decided to locate such a device upbull

stream of the turbine it would be necessary to allow disbull

tance tor the flow picture to become reestablished prior to

entry to the turbine A contused flow making transit of

the turbine passages would only contribute additional loesbull

ea Such a distance allowance would be perbapa 20 to So

diameters (2$ Pbull 119-123) In large penstocka th1a would

repreaent a considerable distance Which from the viewbull

points ot convenience and control would be undesirable

Attempts to ascertain the effect or additional tlov

16

reduc ion at the wicket gatctsmiddot wae ade 1n the lfadraulioe middot

Laboratory of Oregon St middot te College in 1933 (20) Three

d1tterent thode ot reducins the tlow were t~ied

(l) Locking in the cloeed position pairs or wicket

gatea located opposite to eaeh o~er on the -periphery ot

the wheel

(2) Locking adjacent gates in an open position by

inserting blocks of wood between them and

()) Suocess1vely looking adjacent gates in the closed

position

The results indicated a arked reduction in both power

and efficiency when compared to the curves tor normal gate

operation However it was demonstrated that it was poae1bull

ble to ahitt the power and tfieiency curve ill relation to

turbine apeed lbis important feature will be diacussed

later

ihe main conclusion of the investigation was that conbull

trol by the conyent1onal wick t gates was auper1or to other

methode egtt control exercised at the gates the aelvebullbull

It would app$ar that the bebullt location tor flow conshy

trol would be in the draft tube since none of the objecbull

tiona prev1ously mentioned wou~d eziat there

As bas been stated previously the sole object or the

17

18

turbine is to produce power as etfic1ently as possible

The equation tor the power output of a turbine () Pbull 227)

PaWHe HP (4)55o bull bull Assuming the head 1a constant and a g te located in

the draft tube decreases bhe rate ot flow the power eu

only be increased if the etticiency increases

The ettective head Gn the turbine 1s conventionally

d r1ned as the difference between the auma ot the elevashy

tion head pressure head and velocity head at the entrance

to the turbine casing and the tailrace ($ Pbull 872)

lt ie recognized that the theoretical treatment ot

shock loss as given is highly approximate and serves only

to dictate certain trenda For example the area at xit

rom the wicket g tea CfUl be measuPed with some exactness

but there exists no guarantee that the wateP particles will

complet-ely fill the apace oz- will exit at the establiahed

g te angle The same can be said of the exit trom the

runner blades AssUIlptiona were implied which would indishy

cate that all water particles passing a given croea section

ampH traveling at the same velocity in the same direction

the e alone are autt1c1ent to show 11m1tationa in a theoretbull

1eal approach to the problem

Assume a turbine with ordinary wicket gates tor oonbull

trol compared gainst the same turbine with a gate in the

18

draft tttbe tor supplampment1ng control or the rate ot rlow

Let it also be assumed that the two turbines are opershy

ating at the same point It 1s desirable to predict relabull

tive performance of the two turbines 1 this point of

operation is such that edd7 s hook loss ot reasonable proshy

portions is present in the fir t turbine

~ tull erteot of the shock loss will be exper1 need

by- the fir t turbine

lhe second turbine will derive certain advantages 11

the gate in the draft tube is adjusted to reduce the tlov

1n the proper amount Since they vary a the square ot

the veloo1t7bull the lossabull in the aeroll case wiomiddotket gate

and runner passages will decx-ease aetet-r1ng to Figure 2 1

it can be seen that a decreased velocity v1 w-ill reduce the

eddy shock losa

The ent loss in the dJtaft tube of the second turbine

will be the sum ot the tr1ct1onal loss and the velocity

head at ex1t The velocity head dissipated will be greater

due to the closing action or the gate but the reduoed

t~ictional loss which ia a tunction ot the rate of tlow1

will partially balance this

It 1a entirely possible that the net reduction in

losses in the second turbine will lead to a greater ettibull

oiency and more power output than 4eYeloped by the first

turbine

19

In Figure 3 the plot ot power output against turbine

speed for Curv A~ represents the typical family of curvea

tor a reaction turbine Th b st sp ed is the locus ot

points connecting maximum eft1oiency at each gate opening

The operating speed is the coZUJtant turbine apeed which

passes through the point ot maximum efC1ciencr of the turbull

bine The plot of turbine efficiency against power output

for Curve A is also ahown

It the turbine with flow regulation in the dratt tube

oan demonstrate superior power and efficiency at part loads

the effect would be the same as a shifting or the power

curves toward the condition shown fop Curve B 11 Thisbull

illustrates th ultimate case of the uperpoait1on of best

and operating speeds It will be noted that the pet-form~

of the turbine ot Ourve Bu 1a better than that of CUrve

A at part loads because of ita ability to sustain a relabull

tively high etticienoy ovel a Wider range of power output

o Reguireaegts tort Test Velitication

It is desired to deterra1ne the effect on the turbine

performance b) the addition of a gate in the dratt tube

Th step in the teit will bet

(1 To determine the power output and efficiency ot

the turbine tor wicket gate settings above and below rated

conditione for a wide range ot speed

20

CURVEAbull

TURBINE SPSBD TURBID SPEKD

POIBR OOTPOl

Figure 3 - Turbine Performance Curves

21

22

(2 peat (l) with the gate installed in the drat

tube

(3) middot Converting middot all data to a constant head compare the

powere and effioiencies at the same wicket gate setting and

turbin speed tor the two cbullses

If the ddition or the gate indicates an improvement

in power output and efficiency and the powe~ curve shifts

to the right along the turbine apeed scale the advantage

ot draft tube con~ol of the flow will hav been demonshy

strated

Chapter IV

A E9J11pment

ih turbine used in this test is lJ 5 1nch Pelton

reaction turbine with a rated output ot 30 horsepower under

a head of 56 feet at a speed ot 720 reYolutiona per minute

Views of this turbine are hovn in Figures S and 6 The

turbine is installed on a concrete pad located over an open

channel in the Hydraulics Laboratory at Oregon State Colshy

lege The date of manufacture of this turbine was 1915

The water was delivered to the turbine from a sump

reservoir by two pumps operating 1n parallel Each pump 1a

an 8 inch Pelton double suction centrifugal pump witb a

rating of l$00 gallons per minute at a head ot 75 teet with

a speed ot 1175 revolutions per minute Tbe inlet tlange

ot tne turbine is $pprox1mately 18 feet above the center

line of the pump

A direct current generator was coupled to the turbine

to receive tne power d veloped as shown in Figures 4 and 7 The generator is a Spr gue Electrodynamometer rated at SS horsepower with a speed range of 7$0 to l$00 revolut1one

per minute The classification is type LO 26A 2)0 volta

Figure 5 - View of Test Turbine

Figure 6 ~ View of Test Turbine

and 149 amperes lbe generator ti ld was aepar tely

excited using direct current from a motor g n r tor ampt

(l$ p 4~8)

The power output of the generator waa dissipated in

the water rheostat (3 p 488-489) shown in Figures 9 and

10 The galvanized tank contain d water ot variable d pth

on an electrode ot cast iron m aauring 1bull x 1 x 1

In the initial installation of the turbine it was

intended that the power output should be measured with a

Prony brak bull For th purpoa68 or this teat it was decided

that the brake was too instable and the generator was

substituted The platform for raising the generator the

nee asary two teet for alignment was built out of available

material In this case heavy laminated wood blocks reiashy

torced with other timbers were used and bolted through the

concrete deck (11 Pbull 36-$7)

Due to the light concrete deck the lack ot mas in

the platform and the slight misalignment in the flexible

coupling ao e vibration waa encountered It seemed to

ncr aae linearly to a maximum at the speed of bout 750

revolutions per minute Above this speed no vibPation was

noticeable The vibration waa not se~ere and does not

appear to have materially affected the test results

26

B Intrumentat1on ~ eaeur1ng Devices

The pressure head at inlet to the turbine vaa meaave4

bymeane ot two )6 inch waterbullmeroury manometerbull connected

in series as shown in Figure 8

The terminal voltage ot the generator vas meaeured by

a laboratory voltDleter with a range to )00 yolta and callbull

brated to within 15 Yolta

The armature current bull and hence the line current was

measured by a laboratory ammeter with a range to 150 amperea

and callbrated to w1 thin o 7S amperes

Tae rate ot tlow was established by weight and time

meaeurementa The weighing ank has a capacity ot 121 000

poundsJ the weight belng indicated by Toledo direct reading

scales Timing was done with a hand atop watch with clivibull

aion ot 02 second

he ~ater level in the tailrace was dete~1ned by a

hook gauge lhie was read to the nearest 001 toot

The turbine and generator speeds were eaaured by a

hand tachometer The technique of almost cont1nuoua readbull

ings of the speed gave an error ot no more than 5 revolubull

tiona per minute

c Operational Procedure

Atter the water level in the aump was checked to

insure an adequate auppl7 the puapa were primed and

27

Figure 7 - Test Generator and Plattorm

Figure middot8- Instrument Board and Field Rheostat

28

started After venting they were valved for operation 1n

parallel

The motor generator set was started to supply the

field current and the circuit breaker was closed Water

wa added to the water rheostat to the level shown in

Figure 10 ~ field current wae minimized by cutting in

all the f ield resistance in the field rheostat of Figure 8

The l2 inch gate valve shown in Figures 5 and 6 waa

slowly opened and the turbine and generator brought up to

speed The 12 inch gat valve and turbine were vented and

the pumps were checked to insure neither had lost ita prime

lhe water rheostat offers very steady load 1f the

water level is essentially constant and the water temperabull

ture 1a fixed () p 488~89) In order to maintain this

constant temperature it was decided not to circulate the

water in the rheostat but rather to allow the water to

boil thua achieving the desired result A standing wave

was set up on the face ot the electrode by the boiling

action but a atable load was eatablished except at very

low water leYels where th11 agitation led to fluctuationa

in the line current

After putting the turbine and generator on the line

maximum power was dissipated in the rheostat by redueing

the turbine speed to between oSO and Soo revolutions per

minute Salt vas added to the rheoetat wat r to increasemiddot

29

Figure 9 - View of Water Rheostat

Figure 10 - View of Water Rheostat

Separate Field ExcitationFrom Motor-Generator set Compound Water-Mercury

---shy

re Manometer

I Q)

~ 0

~

Book Gauge

Open Channel

I

Slap Reservoir

Figure 11 - Wat~r Flow Diagram and Electrical Layout

31

waiting pe~iod ot perhaps an h~ followed

while the boiling point or the water wbulls reacbe4 During

this ti+ne the manometer was vented end eheoked electrical

measur1ng 1nstlUments were connected end the hook gauge was

adjusted tor elevation

It required about two- houtte tor the generator to reach

its normal operating tempe-ratu~e_ After the water in the

rheostat and generator had reached their operating temperabull

turea it was possible to begin the taking of data

The only vaPiable which was controlled wee the turbineshy

generator speed However the upper l1ut1t of safe line

current was slightly over 100 ampJilPampPes and the eireuit

breaker would open when the current reached lOS ~ere bull

Control was exercised by means ot regulating the water

level and salt 1n the water rheo tat and the res1stsnoe of

the tield rheost t~

The etfeet ot each type ot regulation on the three

variables is shown below

Volta Aaperebull Speed

Inc Dec Inc Dee~ Inc Dec

Wa~e1 Level Inc Dec~ X

X X X X

X

Salt Concentration

Inc Dec X

X X X X

X

field Resistance

Inc Dec

X X

X X

X X

32

Jlot all methods gave the ame amount ot change in a

given variable and a period of experiment and trial led to

the following scheme starting the rune with the lowest

turbine speed the water level was high with a high amount

ot salt and the field resistance was cut completely out

Aa it became necessary to increase the speed tor each

aucceasive run either cutting in t he field resistance

decreasing the salt concentration or lowering the Vater

level would produce the desired result However decreasbull

1ng the salt concentration had to be done Without a net

gain in water which led to a tluahing procedure that was

not particularly good because cold water was introduced

which required time to heat to the boiling point Cutting

1n additional field resistance was a good method but th1a

increased the amperage possibly to the point of opening

the circuit breaker Lowering the water level was aatiashy

factol1 until the level got too low causing the current

fluctuation previously mentioned Actually it turned out

that a combination of lowering the water level and cutting

field resistance in would carry the speed from ita minimum

to 1ts maximum value it the proper choice were made each

time the speed waa to be changed At the conclusion of

each aet of runs at a high speed the water level would be

low and the field resistance high

33

TURBINE

PAD AND DECK

TAILRACE

WATER SURFACamp

CONCRETE

DRAFT TU1B INSERTS

7 5( DRAFr TUBE

FLltJI ARIA

5~ DRAFT TUBE

FLOI ARSA

Figure 12 - Sketch of Draft Tube and Test Inserts

34

Figure 13 - View of Draft Tube Insert

Figure 14 - View of Draft Tube Insert

D c __ ~s_middot hedu_le of

A number was assigned to each run The fi~st number

applies to the draft tube tlow areas

1 bull 100~ flow area or 0~ oonatriction

2 - 7S tlow area or 2$ conatr1ct1on

3 SoC flow area or so~ constriction

The second number refers to the wicket gate openings

9 over gate opening

6 bull intermediate gate opening

4 bull one h lt gate opening

The third number 14entif1ea the location of the particular

1Wl in a set ot rona made at a given dratt tube tlow area

and wicket gate opening

fnua run number 1bull4bull10 would identity this as the

tenth run ot a set made at halt gate with 75 ot the draft

tube t1ow area

Rune w re made tor a g1yen dratt tube condition

Firat tor tull 41-aft tube flow area seta ot rune were

made for the overgate halt gate and intermediate gate

conditione An insert was placed in t he draft tube and

rune based on the same gate conditions were made tor the

7S~ draft tube flow area case The insert was then changed

to allow only $~ draft tube flow area

The inserts are sketched 1n Figure 12 and photographed

ln Flgurea 13 and 14 They oonaisted of circula~ segments

36

or l2 ineh plywood mount 4 on wooden legs 10 inches high

The 1nse7te were placed in position and secured by th use

ot a-clamps on the legs and the outside ot the bottom of

the draft tube The obvious disadvantage to this method

waa the neoeasity tor draining the water from the tailrace

tor a change ot 1naert The advantage vas of course the

simplicity ot design and construction

Chapter V

DATA-A Original Data

The normal data-taking crew consisted or two men

Assuming adjustments having been made to secure a certain

turbine speed (aee section on Operational Procedure) one

man would take semi-continuous speed readings with the hand

tachometer until a state or rotational equilibrium was

reached This could be only a period or two minutes up to

ten or tifteen minutes As soon as steady speed was

assured the data taking would begin The second man went

to the weighing tank Where a minimum ot three weighingamp

were made The requirement was to get three consecutive

readings such that the ditterence between tbe smallest and

largest time did not exceed 04 seconds The time to

collect a given weight ot water was then assumed to be the

arithmetic average of the three times He then went to the

hook gauge determined the hook elevation and then

recorded the data on the data sheets The first man meanshy

while had taken readings of the line voltage line current

and manometers and checked the turbine speed by multiple

readings During the length of the run all values were

38

checked to determine mean values for recording

The minimum length of one run was about five minutes

If one or more measure ants tended to drift during the run

all values wer discarded and a new run began as soon aa

qu111br1um was stabl1shedo

B -0-al_e_u_l_a_t--d Data

The h d on the tu~bine 1 defined by

($)

The maxtmwm velocity V4 was equal to about o8 tampet per

secon4 which makes it a negligible quantity when converted

into velocity head

An engineerbulla level was used to deterine the d1ffePshy

ence 1n elevation between the compound water-mercury manoshy

meter and the hook gauge Using this value the equation

for turbine bead becomes

where z4 is the hook gauge reading

The rate of flow 1 cent

w weight or water collected average time to collect

The inlet velocity v1 vas calculated by dividing the

weight rate or flow by the specific weight of water and the

)9

area ot ~e inlet pipe This was equivalent to dividing

the weight rate of flow by 490 Then the power input to the turbine is equal to

WHpin rri

10 (6)

Also

(P ~ut) Turbine

(P out) + Generator

(P lost) Generator

The power output of the generator is simplJ the

produot ot the terminal voltage and the armature (line)

curPent The power lost in the generator can be subdivided

into copper losses and stray power losses lo evaluate

these cunes based on losses of an identical generator

11leampsured by the Department ot Mechanical Engineering were

used The loss curves are reppoduced in part in Figures

15 and 16

Determination ot generator losses proceeds as tollowau

(1) From Figure 15 detem1ne the vo1tage drop in the

armature circuit using the temperatures of 1220 F and the

meaaured current

(2) The induced voltage is t~e sum of the terminal

voltage and the voltage drop 1n the armature circuit

() Entering the induced voltage and the turbine speed

into Figure 16 the stray power loss can be determined

(4) The copper lose can be evaluated from Figure 1$

using the measured current and the temperatlll-e of 1220 P

40

25 ~------~--------~--------~------~

U) -U) - 20

f-4 ~

-~ -gt 0

0

VOLTAGE DROP

~ - i -

- bullbullbull bull - -middot-middot -+ ~- + -t--+ ~ - ~ middotbull ~-~ middott- -+----- _ -4 middotmiddot- --~-+-t---r~~ ~--+t-t- - ---t-c-++~-ulf--

0 50 75 100

Figure 15 - Curves of Generator Voltage Drop and Copper Loss

41

1200

1000

800

600

800

0

0

~-

middot--~ 1shy --1 + bull l

100

I -

150 200

IIDOOED VOLTAGB (VOLTS)

Figure 16 - Curves of Generator Stray Power Loss

_ j

-bullshy -L---- shy middot -shy

250

- r

42

(5) The generator los os equal the sum of the eopp r

loss and stray power loss

~e efficiency or the turbine is taken as

etticiency u e =P out (8)Pin

~ample pound Determ1n1gg turbine Power Output

The following data are taken trom that ot Run 1-9-1

Line voltage 1040 volts Line current 870 amperesSpeed 355 revolutions per minute

The induced voltage 1a determined as follows

Line voltage 1040

Voltage drop 90 using Figure 15 with line current of 870 amperes and temperature ot 122 degrees)

Induced Toltage 1130 volta

The power output of the turbine is determined as follows

Generator output 90$0 (line voltage z line current)

Oopper loss 7 (using Figure 15 with line current of 870 amperes and temperatUe or 122 degrees)

Stray power lose 470 (using Figure 16 with speed ot 355 revolutions per miDUte and induced voltage or 1130 volts)

Turbine power output 9527 vatta

or turbine power output 1s 12z2 horsepower

43

The conversion of the calculated data to a constant

head is based on the conventional assumption of constant

efficiency regardless of turbine head For a constant head

ot 81 teet a purely arbitrary figure the tollowing relashy

tionships are ass1lJiled to be true

I ____L (9) (i)l72

(10)

For these two values the specific a peed may be combull

putedt

N t Jt VPt (11)8 243

Chapter VI

~RESULTS

A -Pr_e_ae_n_t_a_t_t_o~n g Reaultbull

Graphical presentation ot the results ot this te1t

are given as follows

Figure 17 -Turbine characteristics with 100~ dratt

tuba 1low area

Figure 18 - Turbine characteristics with 7S dratt

tube tlow area

Figure 19 bull Comparison ot power and etticiency at

over gate conditions between 100 and

75~ draft tube flow area

Figure 20 bull COZQparison of power and ettic1ency at

halt gate conditions between 100~ and

7S~ draft tube flow area

Figure 21 bull Comparison of power and etticiency at

over gate condition between 100~ and

So dratt tube tlow area

Figure 22 - Comparison in variation ot apec1t1c

speed between 100 and 75~ dratt tube

tlow area

50

45

20

-bull - 1--shy40

bull J-~ 30

~ ex

~ 20

~~ ~ -)q

I

~ - _

- -

10~ OF DRAFT TUBE FL(Jif AREA

CONSTANT HEAD OF 8l FEST10

POIER OUTPUT EFFICIENCY SPECIFIC SPEED

0 ~--------------_--------~------~------~ 400 600 800 1000 1200 1400

TURBINE SPEED (RPM)

Figure 17 - Turbine Char~cteristics with 100 Draft Tube Flow Area

50

46

-bulllle

~ 7 ~ OF DRAFt TUBE FLOW AREA

0 -~~-rl C05STAMT BEAD OF 81 mET 1J~

POIER OOTPUT ---+- ---o ~_H EFFICIDCY ~ I shy

bull ql SPECIFIC SPEKD - ~ -

bull ~ J 10 L rmiddotr- r- -

bullz- I

~~ 30 ~~--~----~~-

20 ~ ~ middot-shy

26

~~ 25

~0 ~r-----i (

Tbull -bullshy

400 600 800 1000 1200 1400

TURBINE SPEED (R PK )

Figure 18 -Turbine Characteristics with 75 Draft Tube Flow Area

47

EFFICIENCY 60

1-----shy

-~ 50~--~--~~-~middot middot middot middot r~-~----~~~~---4~-r~-~~gtt

II

POWER~ J ~ bull bull

u I

sH

40~------+-------+---- -~~--~~-~~~~

~----~rl 1 bull

I

I

0~--------------~------_------~--------

~ -OVER GATE CONDITION

COIJSTANT HEAD OF 81 FEET

0 o 10~ DRAFt TUBE

_-- _ 7~ DRAFT TUBamp FLON AREA II

10_~-----+--------r-------r----~~

400 600 800 1000 1200 1400

TURBINE SPEED (RPM)

Figure 19 middot - Comparison between 75 and 100 Draft Tube Flow Areas of Power and Efficiency at Over Gate Conshydition

48

t

bull --4 r ~- ~ middot~

70 1-----------+-~~~~~+middot ~ ~~ middot middot -~~--~~--------~~----~-+1

-~-

Atbull bull

lla-

60

amp0

40

20

10

oampOO

t _ - - ~-+- - -~-

l2 GATB COJIDITIOJJ

COJISTABT HJW) OF 81 JBET

o 0 lOQ( DRAFl TUB8 FLOI AREA

e-- - e 75 DRAFT TUBE FLOW AREA

800 1000

- r-

~

TURBIbull SPBIID (RPII)

Figure 20 - Comparison between 75 and 100 Draft Tube Flow Areas of Power and Efficiency at Half Gate Conshydition

49

60

50

-40

bull 30

IIQbull

20

10

0

400

- t - ~

EFFICIENCY

_J bull - bull bull

~ r r middot t -+ shy L -t -

OVER GAD COliDITIOI

CONSTABT BEAD OF 8l FBB

o o 10~ DRAFt TUBE FLOI ADA middot--- 5~ DRAF TUBE FLQPi AREA

600 800 1000 1200

Figure 21 -Comparison between 50~ and 100~ Draft Tube Flow Areas of Power and Efficiency at Ove~ Gate Conshydition

50

25

20

15

10

0

Figure 22

~- T -4 -t- -l --~-

t-~ I

middot --~- t ~---- _ __ _ + --

----~- --r-- --

~-=J-~-=-~ -==~ _ ~- -- ---f---1 - shy

CONSTANT HEAD OF 81 FEBT

o--o 1~ DRAFT TUBE FLltll AREA

75C DRMT TUBK FLCIJ AREAmiddot--middot-middot 600 800 1000

TURBINE SPEED (RPK)

Comparison of Specific Speeds for 75 and 100 Draft Tube Flow Areas

51

B Discussion 2 Result

Consideration of Figures 17 and 18 indicates the

overall eftioi ncy pattern or hill is significantly or

rounded for the 7$~ flow area than for the 100~ flow area

bia implies a greateP efficiency is possible at speeds

leas than or greater than design speed with an insert in

the draft tube However the muilDum efficiency is lemiddotas

Direct comparison at over gate conditions is made in

Figure 19 ~e same general trend is noted tor both the

etticiency and power curves for the 7$~ flow area case

The eurves show higher values at overspeed than do the

correaponding cWvea for the 100 flow area case It ia

not clear whether the curves have been shifted by the dratt

tube constriction or whether the curves simply bulge past

the normal curves at both overspeed and underspeed condishy

tions The power curves apparently peak near the aeme

point bullalthough maximum power is still obtained with the

normal draft tube area

For the comparison at halt gate operation shown in

Figure 20 a general improvement has apparently been made

by restriction of the draft tube flow area At every speed

the etticienoy and the power is greater for the restricted

tlow case The two ett1o1ency curves and two power curvea

are practically parallel throughout the speed range ot

teat

As the flou aroa i e decreased still farther a s1gn1

ticant change appears Reterr1ng to Figllle 211 tor the $0

flow area curves it a obvious that exit losses have

become excessive at the overgate condition because the

efficiency and power are everywhere leas than tor the case

of normal draf t tube area

Earlier it was pointed out t hat 1t the r esult s 1nd1bull

eated an increase in both power and ef tieiency- t hen it

could be assumed tha t the additional los s i ntroduced with

the draft tube insert is less than the diminished losses

due to leas shock losa and water passage losses For the

places where both the efficiency and power have been

increased we can assume that the insert has improved turshy

bine performance

For the places where the power haa been decreased

nothing can be said as to the elimination of ampbock loss

because the new lose present with the drat tube insert has

overshadowed any gains in eftecti Ve head upatJ-eam of the

insert

Near the peak of the efficiency hill howeve~ it may

be pointed out t hat shock loaa ie a minimum with a normal

draft tube and the insert merely adds an additional loss

with the resultant decrease in maximum efficiency tor the

7$~ flow area case

Perhaps the most s1gn1ticant set of eurves is shown aa

53

Figure 22 In this graph values of specific speed tor the

75 and 100~ flow area cases for both over gate and one

halt gate openings are plotted against turbine speed At

every speed and both gate openings the value ot specific

speed for th 75~ flow area case is greater than that for

the 100 t1ow area ease

Since the head is a constant for both situations this

may be interpreted in either of two ways trom equation

(11)

(1) For the same turbine apeed restriction of the

draft tube t1ow area resulted in greater turbine power

(2) For the same power amputput the turbine with 75~

draft tube flow area operated at a greater speed than did

the one with 100 flow area

Since the required diameter of a turbine varies

inversely with the speed the second interpretation could

be stated such that a smaller turbine could be used to

develop the same power output

Whether viewed trom the aspect of increased power

greater speed or reduced size the performance of the turshy

bine with reduced draft tube flow area is superior to that

with the nolmal flow are in the draft tube

The curve of specmiddotific speed versus turbine speed for

the so draft tube flow area case at over gate cond1t1ona

was not included in Figure 22 This curve lies below that

for the 100~ flow area c se at all speeds

In elaboration ot the second interpretation of Figure

22 attention is directed to the relative magnitudes ot

increased apee1f1c speed tor the two gate openings Assumbull

ing that the increase in specific speed implies a shift ot

the power curve to the right along the turbine speed scale

the power curve would be shifted more tor tbe halt gate

opening than tor the over gate opening

It thia trend could be extrapolated to the other gate

openings the tendency can be seen tor the line ot beat

speed to rotate toward the line of the operating speed as

illustrated in FigtU-e ) The advantage of this has already

been discussed

This particular turbine has a low specific speed tor a

reaction turbine Aa the rated value of apecitic apeed tor

reaction turbines increases the line ot beat speed departs

even more radically from the line of operating bullpeed It a

test similar to this were conducted on a reaction turbine

ot gleater specific speed it is pJobable t hat the rotation

ot the line of beat apeed would become more p~onounced

The scheme used in th1a teat had two obvious dr wbull

backs The first was the decision to leave all the wicket

gamiddottes installed tor all conditions ot the draft tube

These gates predominated in control of the tlow The

inserts added to the draft tube merely acted as auxiliary

55

contrGla

The aecond drawback was the choice or device to place

in the draft tube The reasons foll selection of this type

of device have been previously mentioned It is to be

anticipated that adaptation ot dratt tube flow control

would result 1n a better device for an actual turbine

installation Such apparatus might take the form of a

pneumatic bladder or a h7drau11oally operated variable

venturi section in the draft tube It is conceivable that

the gate as used in this test might be adapted also

Chapter VII

OONCLtJSIOfS

From the results of this test the following eonolubull

e1ona aa to the effect ot a variable draft tube flow area

on the performance or a r action turbine may be drawn

(1) The effect ot a variable draft tube tlow area 1a

generally favorable upon the operat1Gn ot a reaction turbull

bine because or the tendency tor the line or beat speed to

rotate toward the line ot operation This resulte in

better performance of the turbine at partbullloads

(2) he etf1o1ency eh111 tor the turbine beeomaa JDore

tlat at the top leading to a smaller max1JilWD effic1enc7

but e reater etticieney at other pointe of operation with

the insertion ot an auxiliary control ror the rate ot tlov

in the draft tube

(3) The power output of the turbine will increase at

over speed over gate conditione as well a at part gate

conditions with the proper amount or draft tube eonatr1cbull

tion or flow

(4) It is possible to eliminate at least partially

eddy type shock loss by tho introduction ot flow control

in the draft tube

BIBLIOGRAPBl

1 Addison Herbert A treatise on applied h-draul1cs New York Wiley 1954 724 Pbull

2 Allen o M and I A Winter middot Co111parative testa on experimental draft tubes Tranaact1ons ot the American ociety ot Civil Engineers 87t893bull970 1924

3 Barrows a E Water power engineering 3d ed ew York McGraw-Bill 1943 791 Pbull

Bovet G A Modern trenda in hydraulic turbine design4middot in Europe Tranaactions of the American Society ot Mechanical Engineera 75975bull993 1953bull

s Oreager William P and Joel D Justin Hydroelectrichandbook 2d ed New York Wiley 19$0 1151 Pbull

6 Daily Jamea w Hydraulic machinery Int Hunter Rouses Engineering hydraulics Hew York Wiley 19$0 p 8$8bull99

Daughertybull Robert L Bydraulie turbines ew Yorkbull7middot MoGrav-Hlll 1920 281 Pbull

8 Daugherty Robert L Inveat1gat1on of tne performance ot a reaction turbine ~anaactiona or the American Society ot Civil Engineers 7811270bull1304 1915

9 Davie L M Model and prototype testa Int Trend in hydraulle turbine practice symposium lranaactions ot the American Society ot Civil Engineers 1o63S3middot368 1941

lfJ Doland James J Hydro power engineering Hew Yorkbull Ronald 1954 209 Pbull

11 Gandy Theodore s and Elmer c Schacht Direct curshyrent motor and generator troubles operation and repair New York McGraw-Bill 1911 293 Pbull

12 Gibaon Arnold H Hydraulics and ita applications5th ed London Constable 1952 813 Pbull

58

13 Button s P Component loases in Kaplan turbinebull and The prediction of efficiency from model tests Probull coedings of the Institution or Mechanical Engineers168743-762 1954

14 Knapp R T~ Oavit t1on mechanics and its relation to the d sign or hydraulic equip ent Proceedings or tne Institution ot Mechanical Engineers 166150bull16) 1952

15 Langsdorf Alexander s Principles of direct curHnt mach1nee 5th ed New York r~cGrawbullH1ll 1940 746 Pbull

16 Lsrner Chester w Characteristica of modern hydraubull lie turbines Trans e~ions of the ~~erican Society ot Civil Engineers 66306-386 1910

17 Linsley Ray K Jr and Jobulleph B Franzin1 Eleshyments of hydraulic enginebullring New York McGrawshyBill 19$5 $82 Pbull

18 Mead Daniel w Hydraulic machinery llev York McGraw-Hill 1933 396 Pbull

19 ead Daniel w Water power engineering New York McGrawbullRill 191S 843 Pbull

20 Mockmore Charles A Part gate operation at water turbines Corvallis Oregon State College Department ot Civil Engineering 1933 11 numb leaves (Unpubshylshed typescript)

21 Mockmore Oharles A Flow characteristics in elbow dratt tubes Transactions of the Amez-ican Society ot Civil Engineers 103402middot464bull 1938

22 Moody L F Hydraulic machinery In c v Davis Handbook ot applied hydraulics New York McGrawshyHlll 1942 1082 Pbull

2) Ptau At-nold Hydrbullulie turbine handbook ld ed Milwaukee AllisbullOhalmers ManufactUIing Company 1948 70 Pbull

RheingalUI w J Recent developments in Francis turshybines Mechanical Engineering 74189-196 1952

25 Russell George E Hydraulica 5th ed New York Henry Holt 1942 466 Pbull

26 Safford A and E P- Hamilton American mixed tlow turbine and ita setting Tranampactions or the Amerieal Society of Civil Engineers 851237bull1)56 1922

27 bull Spannhake W1lhe1Dh Problems or modern pump and tur b1ne design Transactions of the American Society of Mechanical Engineers 56e22$-248 1934bull

28 Sutherlandraquo R A Better ethod or representing and middot tudying water turbine performance ~ansaetions ot thmiddote American Society of Mechanical Engineers 68t675bull 686 1946

29 Teats ot five models or draft tubes tor turbines Engineering News-Record Pbull 182-184 Aug 2 1923

30 White w M American hydztaulic turbines Mechanical Engineering S2t390bull39S 1930bull

31 White w M lhe hydraucGne rega1ner1 its developmentand appl1eat1ons 1n hydroelectric plants Meohanlobulll Engineering 43t37Sbull380 1921 middot

32 Winter I A Economic principlebull in designbull Int Trend in hydraulic urbin practice bull a ampoeiumTranaaot1ona ot the American Society ot Civil Engineerslo6332bull3S2 1941

33 Wiel1cenua G F Fluid mechan1ca or turbo-machineryNev York McGraw-Hill 1947 613 Pbull

APPENDICES

c

Appendix A

NOATIOB

A Angle between the absolute velocity vector and the tangent to the rwmer Subscripts 1 and 2 refel to entrance and exit ot the runner blade

B Angle between the relative 1elooity vector and the tangent to the rwmer Subscripta 1 and 2 refer to entrance and ezit or the runner blade

Angle between the tangent to the runner blade tip and the tangent to the runnel- Subscripts 1 and 2 reter to entrance and exit of the rt1rmer bladebull

Blade angle-gate opening conetant defined by equation (1)

e 09erall efficiency

g Gravitational acceleration assumed constant at 322 teet per second per second bull

H Turbine head detined by equation ($)

m Exit loss coeft1e1ent

Turbine speed expressed in revolutions per minute

Turbine speed under a constant head of 81 teet

specitic apeed of the turbine under a constant head ot 81 teet

p Power output in horsepower ot the tvbine

Power output of the turbine Ulder a constant head ot Sl teet

Pl- Pressure head at entrance to the tUlb1new

l1 Peripheral velocity ot the runneP Subacr1pta 1 and 2 refer to entrance and exit ot the JUnllampr blade

62

v Relative velocity reaulting trom the combination ot the absolute water velocity V and the runner periphshyeral velocity u Subscripts 1 and 2 refer to entrance and exit ot the runner blade

v] Relative velocity vector necessary to produce a tanbull gential entry into the runner blades

V Absolute water velocity Subscripts l and 2 refer to entrano and exit ot the runner blade

v2 Velocity head Subscripts 1 and 4 reter to the ~8 entrance to the turbine and the tail~ace wate~

w Unit weight ot water assumed constant at 624 pounda per cubic toot

V Weight rate ot flow in pounds per aeooncl

XX Velocity component ot ahook See Figule 2

Z Elevation head Subscripts 1 and 4 reter to entrance to the turbine and the taibace water surfacebull

Appendix B ORIGINAL DATA-Run

lfwnber

0-4-1 0-4-2 0-4-3 o-4-4 o-4-S o-4-6 0-4-7 0-4-8 0-4-9o-4-lo o-4-11 o-4-12 0-4-13

o-6-1 o-6-2 06-3 o-6-4o-6middotS o-6-6 o-6-7 o-6-8 0-6-9 o--6-lo o-6-11

Speed

rmiddot2middotbullmiddot(1)

336 38$ 451 S$9 620 669 6lt)$ 120 787 860 932

102imiddot109 bull

352 355 443middot 543middot 620 654AJs32

911 1001 1111

~essure Head rt (2)

410 410 416 426 431 43-7 439 44-9 452 467 482 soo $1 bull $

350 351 35middot7 )66 37-9 37-9 392 41 bull 3 43middot3 460 489

Elevation Bead

fjj $7 $7 $7 $7 $7 $7 51 57 5-15858 $8 58 56 56 $6565656 51 575As5a

Velocit Head

flj 07 07 07 06 06 06 06 os 05 os0404 03

09 09 oa o8 o8 os 07 07 06 o~o

Total Head rt ($)

47middot4 4A44 o 489 49-4 soo $02 $11 $14 $29 5imiddot45 2 576

41 bull $ 416 421 430 44middot3 44middot3 456 47-7 496 523551

Plow

lbtjec

326 324middot317 311 306 30029middot28 middotmiddot middot 386 275middot260 240 218

359 36~35 bull 349 345middot 339 330 318 300 273 240

Line Potential

vyqjbull 1060 1220 ~-0o 1920 2150 2000 2$60 2000 1940 18)015io11 o

1000 1100 139bull5 1760 1925 16$0 1620 1610 1540 1330 870

Line Current

amlscs 960 900 830 740 730655 70bull 0 530 660 600 5imiddot54 6 )60

982 930 860 780 ~3-545

79-5 74-5 670 560 370

P

Appendix B ORIGINAL DATA (Continued)

Run Number

Speed

Pbulltmiddotbullmiddot )

leasure Head ft(2

Elevation Head tt(J)

Velocity He-dfmiddotj

Total Bead tt($

Flow

lbstsec( )

Line Potential vo~ta( )

Line Current

amjs (sect

0bulllt)-1 0-9-2

3ll6 398

28o ~~1

$6 56

1o 10

346 347

390 365

1ooo 1190

aao 835

0-9-3 0-9-4 o-9-S

472 565 632

292 305 312

$6 s6 56

10 o9 o9

)$8 J7~o 37~7

381376 37o

1)6614oo 141o

820 ass ass o-9-6 0-9-7 0-9-8 o-9-9 0middot9-10

680 120 762 844 920

)24337346 366 390

56 $6 56 57 $7

09 os o8 oa 07

)89401 410 431454

367~ 357348 34o 322

1400 1J6o l36o 1310 1170

843 820 7957So 67~0

0-9-ll 0-912

1001 1100

41 bull 7 45-3

s 7 6~0

06 os 480 $18

299 268

980 65$

560 36~5

1-4-1 1-4-21-4-l1-4shy1-4-5 1-4-6 l-4-7 1 4-8 1-4-9 1-4-10 1middot4-ll 1-4bull12

354middot452 562 62q 674shy102 752 760- 863 932

1022 1100-

)82389 4014oa 416 41--7 423 428 44-2 45-7 486 49-2

51S757 51 5-7 5middot15zs sa $8 58 59

07 07 06 06 06 06 06 os o bull o 04 o J

446 45-)46middot4 471 ti7-9480 q86 491505 $19 548 55-4

)28 320 311 306 300 295 291 286 269 2582iimiddot21 bull

1080 14Lo 1550 153-5 1470 141-0 1385 1310 1310 1230 1120 855

970855 875 91-0 94~0 975 966 995 860 77-S 610 4fo

0 ~

Appendix B ORIGINAL DATA (Contirmed)-Run Speed Pressure Elevation Velocity Total Flow Line Line

Number Head Head Head had Potential Current rtjjmbull t~ bttec vyfs am~a12) ( ) ti fli 8

1-6-l $6 33$ $6 0bull9 400 364 1100 93 0 1-6-2 41 34laquo2 $6 oa 406 JS7middot iios a5s l-6-3 500 3~0 5bull6 os 356 1 1 o aos 41middot~1-6~4 35bull4 5-6 oa 41middot 352 16~0 82 0 5~1-6-5 5 bull 36_2 Sbull6 08 42bull6 349middot 161 ~ 0 86~0 1-6-6 622 366 $6 oe 43bull0 345middot 158 0 88~$ 16-A 649bull 37bull1 56 os 43-S 342middot 1570 895 1~- 386 57 07 46-0 192 ) 125A44 333middot 1-6-9 3) 404 5middot1 07 468 317 1620 675 1610 911 42-4 5-7 o6 48-7 298 168 0 61 0 1-6-11 999 451 56 os Sl ll 276 ~2-0 530 1-612 1115 485 58 04 54middot7 238 90 )3 0

1middot9-l 355 279 56 10 )45 385 1040 870 1-9-2 399 28J $6 10 )49 38$ 1140 86 5 l-9-3 ~ ao 291 56 ~0 35middot1 J8J_ JJ6o 815 1bull9-4 579 303 56 09 )68 375middot J4JO 830 l-9bullS 40- 313 )6 09 31middot8 370- 1460 82~0 1-9bull6 679 2) 56 09 3 bull8 364middot 1670 710 l-9-7 682 319 56 o9 384 ) 62 1460 79 5 l-9-8 724 33middot5 56 o8 399 3$6 bull 1480 76 -5 1-9-9 762 34middot3 $6 0 bull 8 407 )48 14910 13middotS 1-9-10 833middot )60 5middot7 os 42$ 339 144$ 686 1-9-ll 926 39middot1 5-7 07 455 318 1290 600 1-9-12 1000 41middot3 0-6 476 298 1115 510$ ~ 1middot9-13 1105 452 s o4 $14 2$6 710 )10

~

Appendix Bt ORIGDIAL J (Continued)

Run Speed Pressure Elevation Velocity Total Plow Line Line Number Head ltead Head jlamp$d P()ten~ibulll Current

r~~~m ft ft lbs~seo voltattj rgj twimiddot t 1 t2gt lt3 ou t ( rt

2-9-1 384 289 S 6 10 35 5 1400 1170 810 2-9-2 443middot 29$ $6 ltimiddot9 360 379middot 11(0 87$ 2-9-J 536 30bull 3 sc 09 )68 374middot 1)40 84 bull) 2-9-4 571 306 $6 09 3~1 372 120bull 0 955 2-9-5 623 316 S6 09 J l )6S UJSo 77$ 2bull9-6 669 327 S6 09 )92 )61 1240 905 2-9bull7 712 )39 56 os 40-3 351 12(0 86 bull0 2-9-8 ~5$~ J48 56 oa 412 348 1290 81 bull ) 2-9-9 04 )63 56 oa 42-7 339 12ltJO 76$ 2middotmiddot9-10 8$2 376 5middot1 07 440 33~- ~ o 710 2-9-11 955 394 5-1 o6 457 300 1100 506 2middot9-12 1000 421 $7 06 48middoti 295 1020 $18 2-9bull13 110~ 463 56 05 $2 267 620 3~0

oshy0

Appendix Gt CALCULATED DAgA

Turbine Run Generator Generator Turbine Turbine Efficiency Turbine Turbine Specit1c

Number OutputKWlt21

Loa~Jes KWlol

Outut K bull (H)

Input RP 12)

middot Percentlt13gt

Speed r~Jmiddot(

0ltput HP ~1

Speed r-m

( 6) middot

o-4-1 0middot4-2 0-4-3 0-4-4 0-4-5 0-4-6 O-qmiddot7o-4-8o-4-9 0-4bull10 0-4-11 o-4-12

1018 1o9a 1220 1)62J40214oa1J4oo 1357 1320 1164 997 718

046 o59 071 092 096 1071oo 134 104 100 109 107

14261sso 17)01948 2008 20322011 1999 19 09 1708 14-84 11o6

281279 27-7 276 215 273271 268 268 26h 258 24-5

soa 555 62$ 705 7)1145 742 74-6714645 51s 45-1

440 sos 585 720 195 sso sao 9$$ 985

1065 1135middot 1230

318 357 319 416 422 419412 39middot9 378 324 260 191

102 12bull4 148 191 21bull 3 22o 233 249 24924middot9 238 221

0-4middot13 418 104 699 228 306 1300 117 18)

o-6-1 982 045 1376 271 $08 496 376 124 o-6-2 o-6-3 G-6-4o-6-5 0-6-6

1023 1200 13 73 J415 139h

051 0middot66 oaa ()bull 96 088

14-39 1696 1958 2026 1986

276 27middot4 273 278 274

$20 61 8 717 7)0726

q95615745 8)5685

390 ll5middot3 sos soo 490

127 170 218 243 2$$

o-6-7 o-6-8 o-6-9o-6-lo

1288 1199 1032 7-45

o9o 094 09$ 096

1846 1733 1511 1128

274 276 271 260

67S 629559 43middot4

980 1085 1165 1245shy

436 )83316 21bull 7

266 276 270 239

0-6-11 322 1oo 566 2141 2JS 1350 101 177 0 --4

Appendix C CALCULATED DAlA ( Continued)-Run

Number Generator Generator

Out2ut Losaes xw LW- 12gt (lO)

Turbine Out2ut

ltPlJ

Turbine Inat lfP Jig)

Etpound1e1ency

PireentDl

Turbine Sed x-~m( 1

Turbine OutEut RPJl)

Turbine Specific

SeeedrIbullntbull

( 6)

o-9middot1 0-9-2 0-9-3 o-lt)-4 09-$ 0bull9-6 0-9-7 0-9-8 0-9-9 0-9-10 o-9-11 0-9-12

aao 994

111$ 1197 1206 1180 11)21081 982 784 5-49 2)9

0middot45oss o6$ 070 07$ 0-77 (l77 or~ o s06o 8 096

123~ 1402 1$80 1698 17bulllS 168$ 16bull18 ~middot5430 1151 a~J4 9

24middotgt24middot3248 25~25 260 260 259 267 266 26middot1 2S2

sos 577 63-7 671 676 650 621 60036J4

327 178

$) 610AlO 3$

92S 980

102$ 1070 1157middot 1230 1300 137Smiddot

44middot4 soo 523 ssomiddot 540so6 46-5 432 368 274 18~8

J46 176 21-1 255 2802s_A 28 289 288 265 231 168

1-4-1 1-4middot2 1-4-3 1-4-4 1-4-5 1-4-6 1-4-7 1-J-8 1-4~9 1-4-10 1-4-11 1-4-12

10bull48 1231 13-S6 1397 1)821375 1))8 1303 1127 953 683) 51

048 067 o7A07 0 bull79 oa1 oss o bullao osa 0lt)0 096 099

J468 1740 1921 1978 1958 19$1 1911 lSSi162 1)98 1045

603

266 264 262 262 261 2512$7 2$6 24middot7 24-3 233 217

551 660 13middot3155 75-6 7~-97 middot4 72$ 67 51middotJ 44middot9 21middot1

475 605 A4220

875middot 910 970_

1000 1090bull 1166 1243 1330

5816

44middot444middot5 430 427 412 392 329 273 188 l0-7

117 101 204 22$ 2)7245 2562sa 257251 222 179

a-C))

Appendix Ct CALCULATED -DATA ( Ocntinued)

1-6middot1 1023 o$2 14-41 26S 505 41~6 26~

54middot5 13middot3l-6-2 1201 067 1boo 625 47-9 17shy~middot41-6bull3 1296 oA9 1 middot43 26 9 700 so5 20bull 4 l-6-4 l3j5 o 0 19~09 268 71bull3 A5o 514 222 1-6-5 1) 5 o81 19(gt4 271 725 51-5 238 l-66 1398 081 198) 27-0 736 8 S13 252~-middot l-6j 1405 083 199i 211 733 885 $middot06 2$9 l-6 13middot9~ 103 2amp 0 279 71 8 985~ 467 ~-69 1228 1 bull 02 17-SS 270 661 109$ 407 ~3~ l-6bull10 1025 100 lSll 26i 573 1175middot 27~S32middot~l-ampu 153 1-00 llft3 26 444 1270 22 24bull8 1bull6-12 294 100 52a 231 22 3 1360 95 172

1-9bull1 904 048 1275 2J4Z $28 S4$ 459 1$2 1-92 98$ oss 13-92 24middot4 57-0 6JO 49bull1 176 1-9middot3 1110 066 1$76 24middot9 63middot4 I2o 536 21-7 l--9-4 1187 072 1685 251 66$ 5 $$ bull 0 261 1middot9-5 llltJ7 1710 25middot4 67-3 93$ 536 28~20-671middot9-6 1186 o 8 1708 25-7 67) 980 $15 2691-9- 1161 oBo 1660 2$middot3 6$6 990 508 29-1 l~- ll-32 oB) 16sect0 2$8 632 1030 471 291 1-9bull9 109$ oa5 2$7 614 1075 29S~middot 0 4imiddot41-9-10 9~91 oas 262 S$1 1150~ 3 o 292 1-9-11 o9o u57 12JiO 21gt 26-77middot74

-45 26sect ~middot91-912 $69 091 sas 25 middot3 1)0$ 196 2J-8 1-9-1) 220 098 426 2)9 178 1390middot 84 16 6

0 0

Appendx C CALCULATED DATA (Continued)

Turbine Run Generator Generator lurbine Turbine Eft1e1eney Turbine lurbine Spee1f1c

Number Output Losses Outit Input Speed Output SPed middot k_-V KW R _ H_bull_P Percent r Thm HP rpm_ (9) tlo) 11) middot (12 _) (lJI ( ) (1$ (14)

2-9-1 9--46 055 1)62 258 528 580 164 2-9-2 1024 056 248 58 4 665 4 9 191iimiddot48 4~middot0 2-9-3 1132 067 05 2$0 641 795 52q 237 2-9-4 1148 065 1027 2$1 -~8 845 525 252 2-9-5 11 77 oso 16-83 253 6 910~ 522 270 2-9 6 1122 071 1600 251 622 960 47-5 2722-9-A 1092 015 1562 257 608 1010 445 2z12bull9- 1052 079 1514 261 580 1060 41middot7 2 2 2middot9-9 986 o82 ]429 26) 542 1105 372 277 2-9-10 915 086 1340 268 500 1160 334 27-6 2-9-11 638 087 972 254 )81 1270~ 229 250 2-9-12 )28 090 828 259 )19 1295 179 226 2-9-13 192 094 383 2$ 6 150 1370 7 3 152

-3 0

Page 19: The Effect of A Variable Draft Tube Flow Area on the

--

12

and its minimum near the rated gate position

(2) For conatant gate opening the shook loss curve

will approximate a symmetrical parabola with its vertex

the point of minimum loas located at the rated condition

of operation (7 Pbull 79)

c Exit Loas

It can be seen from Figure 2 that the exit loss from

the turbine would be v222g if no draft tube were present

The addition of a draft tube permits the gradual reduction

of velocity by an increase in cross sectional area between

the exit of the runner and the exit from the draft tube

The exit loss and the frictional loss encountered in

the draft tube may be placed together in the expression

m va2 (3)Exit Loss ~---2g

For the ideal case of no friction in the draft tube

m is equal to the square of the ratio of the area at exit

from the runner to the area at exit from the draft tube

In an actual turbine installation however friction

will change the value of m (7 p 84-85) to somewhere

between that for the ideal case and a maximum ot 10

In the interest of maintaining a minimum exit loss

the turbine should be designed and operated so the velocity

V2 will be minimum This will occur when the discharge

13

vector is at right angles to the tangent to the runnerbull

ie the angle A2 1e ninety degree bull It ia to be expected

that this condition will be tultilled near the design con~

d1t1ons ot the ~bine

Current design praetiee 1 to have a small component

ot v2 in th$ direction of turbine rotation at rated condibull

tion$ ltS p 938)

For a constant turbine speed the d1seharg or exit

loss is ess nti lly a constant

For a constant gate opening the exit lo s curve is

aptrroximately a symmetrical pa~abola with ita vert x the

point or minimum loss located at a slightly lowe~ speed

th n the turbine rated speed (7 Pbull 79)

Chapter III

PROPOSAL OP ALlERMAlE MFTBO 0 CO TROL-A lz ~ Location 2 Control

Thua tar only practice and theoretical aspects appemiddotrbull

taining to present day turbinea have been d1acuaaed It

haa been presented that control over the ~bine ia ezerbull

oiaed b y manipulation of the wicket gatea located 11101led1bull

ately preceding the runner These gate - upon rotation

modify both the magn1tu4e and the direction ot the entering

velocit7 Moreover it has be n shown that a simultaneous

change in these two variables leads to inefficient operabull

tion by the introduction of shock loss he farther the

point of operation a from the rated conditione the more

aerioua ia the ahock loss encountered

Any attempt to better turbine pertorance at other

than rated conditione and tbne flatten the top ot the

etticieney hill8 must concentrate upon the lessening ot

the ahock loaa It 1a a aumed that 1 provement in the

scroll case gates and runners would lequ1re sueh pertecbull

tion 1n machine work and metal$ as to be prohibitively

expensive

It ie surmised that any move to elblinate eYen parbull

tially the shock loss would require separate control ovel

l$

the flow and gate exit angle Since it is improbable that

d1~ect1on could be controlled at any location other than

where the gatea are situated in current turbines it will

be assumed that guide vanes will be necessary regardlesa or the method used to control the rate of flow

The primary purpose ot th se guide vanes 1s that or control over the direction ot the incoming water They

should be free to rotate in much the same manner as ordibull

nary wicket gates in order to exercise control over th

turbine speed

If the rate ot tlov is to be controlled elsewhere it

must be modified either in the penstock or the draft tube

Devices that could be used are standard valves gates

variable orifices variable venturi sections and associated

flow regulating schemes

Alauming it were decided to locate such a device upbull

stream of the turbine it would be necessary to allow disbull

tance tor the flow picture to become reestablished prior to

entry to the turbine A contused flow making transit of

the turbine passages would only contribute additional loesbull

ea Such a distance allowance would be perbapa 20 to So

diameters (2$ Pbull 119-123) In large penstocka th1a would

repreaent a considerable distance Which from the viewbull

points ot convenience and control would be undesirable

Attempts to ascertain the effect or additional tlov

16

reduc ion at the wicket gatctsmiddot wae ade 1n the lfadraulioe middot

Laboratory of Oregon St middot te College in 1933 (20) Three

d1tterent thode ot reducins the tlow were t~ied

(l) Locking in the cloeed position pairs or wicket

gatea located opposite to eaeh o~er on the -periphery ot

the wheel

(2) Locking adjacent gates in an open position by

inserting blocks of wood between them and

()) Suocess1vely looking adjacent gates in the closed

position

The results indicated a arked reduction in both power

and efficiency when compared to the curves tor normal gate

operation However it was demonstrated that it was poae1bull

ble to ahitt the power and tfieiency curve ill relation to

turbine apeed lbis important feature will be diacussed

later

ihe main conclusion of the investigation was that conbull

trol by the conyent1onal wick t gates was auper1or to other

methode egtt control exercised at the gates the aelvebullbull

It would app$ar that the bebullt location tor flow conshy

trol would be in the draft tube since none of the objecbull

tiona prev1ously mentioned wou~d eziat there

As bas been stated previously the sole object or the

17

18

turbine is to produce power as etfic1ently as possible

The equation tor the power output of a turbine () Pbull 227)

PaWHe HP (4)55o bull bull Assuming the head 1a constant and a g te located in

the draft tube decreases bhe rate ot flow the power eu

only be increased if the etticiency increases

The ettective head Gn the turbine 1s conventionally

d r1ned as the difference between the auma ot the elevashy

tion head pressure head and velocity head at the entrance

to the turbine casing and the tailrace ($ Pbull 872)

lt ie recognized that the theoretical treatment ot

shock loss as given is highly approximate and serves only

to dictate certain trenda For example the area at xit

rom the wicket g tea CfUl be measuPed with some exactness

but there exists no guarantee that the wateP particles will

complet-ely fill the apace oz- will exit at the establiahed

g te angle The same can be said of the exit trom the

runner blades AssUIlptiona were implied which would indishy

cate that all water particles passing a given croea section

ampH traveling at the same velocity in the same direction

the e alone are autt1c1ent to show 11m1tationa in a theoretbull

1eal approach to the problem

Assume a turbine with ordinary wicket gates tor oonbull

trol compared gainst the same turbine with a gate in the

18

draft tttbe tor supplampment1ng control or the rate ot rlow

Let it also be assumed that the two turbines are opershy

ating at the same point It 1s desirable to predict relabull

tive performance of the two turbines 1 this point of

operation is such that edd7 s hook loss ot reasonable proshy

portions is present in the fir t turbine

~ tull erteot of the shock loss will be exper1 need

by- the fir t turbine

lhe second turbine will derive certain advantages 11

the gate in the draft tube is adjusted to reduce the tlov

1n the proper amount Since they vary a the square ot

the veloo1t7bull the lossabull in the aeroll case wiomiddotket gate

and runner passages will decx-ease aetet-r1ng to Figure 2 1

it can be seen that a decreased velocity v1 w-ill reduce the

eddy shock losa

The ent loss in the dJtaft tube of the second turbine

will be the sum ot the tr1ct1onal loss and the velocity

head at ex1t The velocity head dissipated will be greater

due to the closing action or the gate but the reduoed

t~ictional loss which ia a tunction ot the rate of tlow1

will partially balance this

It 1a entirely possible that the net reduction in

losses in the second turbine will lead to a greater ettibull

oiency and more power output than 4eYeloped by the first

turbine

19

In Figure 3 the plot ot power output against turbine

speed for Curv A~ represents the typical family of curvea

tor a reaction turbine Th b st sp ed is the locus ot

points connecting maximum eft1oiency at each gate opening

The operating speed is the coZUJtant turbine apeed which

passes through the point ot maximum efC1ciencr of the turbull

bine The plot of turbine efficiency against power output

for Curve A is also ahown

It the turbine with flow regulation in the dratt tube

oan demonstrate superior power and efficiency at part loads

the effect would be the same as a shifting or the power

curves toward the condition shown fop Curve B 11 Thisbull

illustrates th ultimate case of the uperpoait1on of best

and operating speeds It will be noted that the pet-form~

of the turbine ot Ourve Bu 1a better than that of CUrve

A at part loads because of ita ability to sustain a relabull

tively high etticienoy ovel a Wider range of power output

o Reguireaegts tort Test Velitication

It is desired to deterra1ne the effect on the turbine

performance b) the addition of a gate in the dratt tube

Th step in the teit will bet

(1 To determine the power output and efficiency ot

the turbine tor wicket gate settings above and below rated

conditione for a wide range ot speed

20

CURVEAbull

TURBINE SPSBD TURBID SPEKD

POIBR OOTPOl

Figure 3 - Turbine Performance Curves

21

22

(2 peat (l) with the gate installed in the drat

tube

(3) middot Converting middot all data to a constant head compare the

powere and effioiencies at the same wicket gate setting and

turbin speed tor the two cbullses

If the ddition or the gate indicates an improvement

in power output and efficiency and the powe~ curve shifts

to the right along the turbine apeed scale the advantage

ot draft tube con~ol of the flow will hav been demonshy

strated

Chapter IV

A E9J11pment

ih turbine used in this test is lJ 5 1nch Pelton

reaction turbine with a rated output ot 30 horsepower under

a head of 56 feet at a speed ot 720 reYolutiona per minute

Views of this turbine are hovn in Figures S and 6 The

turbine is installed on a concrete pad located over an open

channel in the Hydraulics Laboratory at Oregon State Colshy

lege The date of manufacture of this turbine was 1915

The water was delivered to the turbine from a sump

reservoir by two pumps operating 1n parallel Each pump 1a

an 8 inch Pelton double suction centrifugal pump witb a

rating of l$00 gallons per minute at a head ot 75 teet with

a speed ot 1175 revolutions per minute Tbe inlet tlange

ot tne turbine is $pprox1mately 18 feet above the center

line of the pump

A direct current generator was coupled to the turbine

to receive tne power d veloped as shown in Figures 4 and 7 The generator is a Spr gue Electrodynamometer rated at SS horsepower with a speed range of 7$0 to l$00 revolut1one

per minute The classification is type LO 26A 2)0 volta

Figure 5 - View of Test Turbine

Figure 6 ~ View of Test Turbine

and 149 amperes lbe generator ti ld was aepar tely

excited using direct current from a motor g n r tor ampt

(l$ p 4~8)

The power output of the generator waa dissipated in

the water rheostat (3 p 488-489) shown in Figures 9 and

10 The galvanized tank contain d water ot variable d pth

on an electrode ot cast iron m aauring 1bull x 1 x 1

In the initial installation of the turbine it was

intended that the power output should be measured with a

Prony brak bull For th purpoa68 or this teat it was decided

that the brake was too instable and the generator was

substituted The platform for raising the generator the

nee asary two teet for alignment was built out of available

material In this case heavy laminated wood blocks reiashy

torced with other timbers were used and bolted through the

concrete deck (11 Pbull 36-$7)

Due to the light concrete deck the lack ot mas in

the platform and the slight misalignment in the flexible

coupling ao e vibration waa encountered It seemed to

ncr aae linearly to a maximum at the speed of bout 750

revolutions per minute Above this speed no vibPation was

noticeable The vibration waa not se~ere and does not

appear to have materially affected the test results

26

B Intrumentat1on ~ eaeur1ng Devices

The pressure head at inlet to the turbine vaa meaave4

bymeane ot two )6 inch waterbullmeroury manometerbull connected

in series as shown in Figure 8

The terminal voltage ot the generator vas meaeured by

a laboratory voltDleter with a range to )00 yolta and callbull

brated to within 15 Yolta

The armature current bull and hence the line current was

measured by a laboratory ammeter with a range to 150 amperea

and callbrated to w1 thin o 7S amperes

Tae rate ot tlow was established by weight and time

meaeurementa The weighing ank has a capacity ot 121 000

poundsJ the weight belng indicated by Toledo direct reading

scales Timing was done with a hand atop watch with clivibull

aion ot 02 second

he ~ater level in the tailrace was dete~1ned by a

hook gauge lhie was read to the nearest 001 toot

The turbine and generator speeds were eaaured by a

hand tachometer The technique of almost cont1nuoua readbull

ings of the speed gave an error ot no more than 5 revolubull

tiona per minute

c Operational Procedure

Atter the water level in the aump was checked to

insure an adequate auppl7 the puapa were primed and

27

Figure 7 - Test Generator and Plattorm

Figure middot8- Instrument Board and Field Rheostat

28

started After venting they were valved for operation 1n

parallel

The motor generator set was started to supply the

field current and the circuit breaker was closed Water

wa added to the water rheostat to the level shown in

Figure 10 ~ field current wae minimized by cutting in

all the f ield resistance in the field rheostat of Figure 8

The l2 inch gate valve shown in Figures 5 and 6 waa

slowly opened and the turbine and generator brought up to

speed The 12 inch gat valve and turbine were vented and

the pumps were checked to insure neither had lost ita prime

lhe water rheostat offers very steady load 1f the

water level is essentially constant and the water temperabull

ture 1a fixed () p 488~89) In order to maintain this

constant temperature it was decided not to circulate the

water in the rheostat but rather to allow the water to

boil thua achieving the desired result A standing wave

was set up on the face ot the electrode by the boiling

action but a atable load was eatablished except at very

low water leYels where th11 agitation led to fluctuationa

in the line current

After putting the turbine and generator on the line

maximum power was dissipated in the rheostat by redueing

the turbine speed to between oSO and Soo revolutions per

minute Salt vas added to the rheoetat wat r to increasemiddot

29

Figure 9 - View of Water Rheostat

Figure 10 - View of Water Rheostat

Separate Field ExcitationFrom Motor-Generator set Compound Water-Mercury

---shy

re Manometer

I Q)

~ 0

~

Book Gauge

Open Channel

I

Slap Reservoir

Figure 11 - Wat~r Flow Diagram and Electrical Layout

31

waiting pe~iod ot perhaps an h~ followed

while the boiling point or the water wbulls reacbe4 During

this ti+ne the manometer was vented end eheoked electrical

measur1ng 1nstlUments were connected end the hook gauge was

adjusted tor elevation

It required about two- houtte tor the generator to reach

its normal operating tempe-ratu~e_ After the water in the

rheostat and generator had reached their operating temperabull

turea it was possible to begin the taking of data

The only vaPiable which was controlled wee the turbineshy

generator speed However the upper l1ut1t of safe line

current was slightly over 100 ampJilPampPes and the eireuit

breaker would open when the current reached lOS ~ere bull

Control was exercised by means ot regulating the water

level and salt 1n the water rheo tat and the res1stsnoe of

the tield rheost t~

The etfeet ot each type ot regulation on the three

variables is shown below

Volta Aaperebull Speed

Inc Dec Inc Dee~ Inc Dec

Wa~e1 Level Inc Dec~ X

X X X X

X

Salt Concentration

Inc Dec X

X X X X

X

field Resistance

Inc Dec

X X

X X

X X

32

Jlot all methods gave the ame amount ot change in a

given variable and a period of experiment and trial led to

the following scheme starting the rune with the lowest

turbine speed the water level was high with a high amount

ot salt and the field resistance was cut completely out

Aa it became necessary to increase the speed tor each

aucceasive run either cutting in t he field resistance

decreasing the salt concentration or lowering the Vater

level would produce the desired result However decreasbull

1ng the salt concentration had to be done Without a net

gain in water which led to a tluahing procedure that was

not particularly good because cold water was introduced

which required time to heat to the boiling point Cutting

1n additional field resistance was a good method but th1a

increased the amperage possibly to the point of opening

the circuit breaker Lowering the water level was aatiashy

factol1 until the level got too low causing the current

fluctuation previously mentioned Actually it turned out

that a combination of lowering the water level and cutting

field resistance in would carry the speed from ita minimum

to 1ts maximum value it the proper choice were made each

time the speed waa to be changed At the conclusion of

each aet of runs at a high speed the water level would be

low and the field resistance high

33

TURBINE

PAD AND DECK

TAILRACE

WATER SURFACamp

CONCRETE

DRAFT TU1B INSERTS

7 5( DRAFr TUBE

FLltJI ARIA

5~ DRAFT TUBE

FLOI ARSA

Figure 12 - Sketch of Draft Tube and Test Inserts

34

Figure 13 - View of Draft Tube Insert

Figure 14 - View of Draft Tube Insert

D c __ ~s_middot hedu_le of

A number was assigned to each run The fi~st number

applies to the draft tube tlow areas

1 bull 100~ flow area or 0~ oonatriction

2 - 7S tlow area or 2$ conatr1ct1on

3 SoC flow area or so~ constriction

The second number refers to the wicket gate openings

9 over gate opening

6 bull intermediate gate opening

4 bull one h lt gate opening

The third number 14entif1ea the location of the particular

1Wl in a set ot rona made at a given dratt tube tlow area

and wicket gate opening

fnua run number 1bull4bull10 would identity this as the

tenth run ot a set made at halt gate with 75 ot the draft

tube t1ow area

Rune w re made tor a g1yen dratt tube condition

Firat tor tull 41-aft tube flow area seta ot rune were

made for the overgate halt gate and intermediate gate

conditione An insert was placed in t he draft tube and

rune based on the same gate conditions were made tor the

7S~ draft tube flow area case The insert was then changed

to allow only $~ draft tube flow area

The inserts are sketched 1n Figure 12 and photographed

ln Flgurea 13 and 14 They oonaisted of circula~ segments

36

or l2 ineh plywood mount 4 on wooden legs 10 inches high

The 1nse7te were placed in position and secured by th use

ot a-clamps on the legs and the outside ot the bottom of

the draft tube The obvious disadvantage to this method

waa the neoeasity tor draining the water from the tailrace

tor a change ot 1naert The advantage vas of course the

simplicity ot design and construction

Chapter V

DATA-A Original Data

The normal data-taking crew consisted or two men

Assuming adjustments having been made to secure a certain

turbine speed (aee section on Operational Procedure) one

man would take semi-continuous speed readings with the hand

tachometer until a state or rotational equilibrium was

reached This could be only a period or two minutes up to

ten or tifteen minutes As soon as steady speed was

assured the data taking would begin The second man went

to the weighing tank Where a minimum ot three weighingamp

were made The requirement was to get three consecutive

readings such that the ditterence between tbe smallest and

largest time did not exceed 04 seconds The time to

collect a given weight ot water was then assumed to be the

arithmetic average of the three times He then went to the

hook gauge determined the hook elevation and then

recorded the data on the data sheets The first man meanshy

while had taken readings of the line voltage line current

and manometers and checked the turbine speed by multiple

readings During the length of the run all values were

38

checked to determine mean values for recording

The minimum length of one run was about five minutes

If one or more measure ants tended to drift during the run

all values wer discarded and a new run began as soon aa

qu111br1um was stabl1shedo

B -0-al_e_u_l_a_t--d Data

The h d on the tu~bine 1 defined by

($)

The maxtmwm velocity V4 was equal to about o8 tampet per

secon4 which makes it a negligible quantity when converted

into velocity head

An engineerbulla level was used to deterine the d1ffePshy

ence 1n elevation between the compound water-mercury manoshy

meter and the hook gauge Using this value the equation

for turbine bead becomes

where z4 is the hook gauge reading

The rate of flow 1 cent

w weight or water collected average time to collect

The inlet velocity v1 vas calculated by dividing the

weight rate or flow by the specific weight of water and the

)9

area ot ~e inlet pipe This was equivalent to dividing

the weight rate of flow by 490 Then the power input to the turbine is equal to

WHpin rri

10 (6)

Also

(P ~ut) Turbine

(P out) + Generator

(P lost) Generator

The power output of the generator is simplJ the

produot ot the terminal voltage and the armature (line)

curPent The power lost in the generator can be subdivided

into copper losses and stray power losses lo evaluate

these cunes based on losses of an identical generator

11leampsured by the Department ot Mechanical Engineering were

used The loss curves are reppoduced in part in Figures

15 and 16

Determination ot generator losses proceeds as tollowau

(1) From Figure 15 detem1ne the vo1tage drop in the

armature circuit using the temperatures of 1220 F and the

meaaured current

(2) The induced voltage is t~e sum of the terminal

voltage and the voltage drop 1n the armature circuit

() Entering the induced voltage and the turbine speed

into Figure 16 the stray power loss can be determined

(4) The copper lose can be evaluated from Figure 1$

using the measured current and the temperatlll-e of 1220 P

40

25 ~------~--------~--------~------~

U) -U) - 20

f-4 ~

-~ -gt 0

0

VOLTAGE DROP

~ - i -

- bullbullbull bull - -middot-middot -+ ~- + -t--+ ~ - ~ middotbull ~-~ middott- -+----- _ -4 middotmiddot- --~-+-t---r~~ ~--+t-t- - ---t-c-++~-ulf--

0 50 75 100

Figure 15 - Curves of Generator Voltage Drop and Copper Loss

41

1200

1000

800

600

800

0

0

~-

middot--~ 1shy --1 + bull l

100

I -

150 200

IIDOOED VOLTAGB (VOLTS)

Figure 16 - Curves of Generator Stray Power Loss

_ j

-bullshy -L---- shy middot -shy

250

- r

42

(5) The generator los os equal the sum of the eopp r

loss and stray power loss

~e efficiency or the turbine is taken as

etticiency u e =P out (8)Pin

~ample pound Determ1n1gg turbine Power Output

The following data are taken trom that ot Run 1-9-1

Line voltage 1040 volts Line current 870 amperesSpeed 355 revolutions per minute

The induced voltage 1a determined as follows

Line voltage 1040

Voltage drop 90 using Figure 15 with line current of 870 amperes and temperature ot 122 degrees)

Induced Toltage 1130 volta

The power output of the turbine is determined as follows

Generator output 90$0 (line voltage z line current)

Oopper loss 7 (using Figure 15 with line current of 870 amperes and temperatUe or 122 degrees)

Stray power lose 470 (using Figure 16 with speed ot 355 revolutions per miDUte and induced voltage or 1130 volts)

Turbine power output 9527 vatta

or turbine power output 1s 12z2 horsepower

43

The conversion of the calculated data to a constant

head is based on the conventional assumption of constant

efficiency regardless of turbine head For a constant head

ot 81 teet a purely arbitrary figure the tollowing relashy

tionships are ass1lJiled to be true

I ____L (9) (i)l72

(10)

For these two values the specific a peed may be combull

putedt

N t Jt VPt (11)8 243

Chapter VI

~RESULTS

A -Pr_e_ae_n_t_a_t_t_o~n g Reaultbull

Graphical presentation ot the results ot this te1t

are given as follows

Figure 17 -Turbine characteristics with 100~ dratt

tuba 1low area

Figure 18 - Turbine characteristics with 7S dratt

tube tlow area

Figure 19 bull Comparison ot power and etticiency at

over gate conditions between 100 and

75~ draft tube flow area

Figure 20 bull COZQparison of power and ettic1ency at

halt gate conditions between 100~ and

7S~ draft tube flow area

Figure 21 bull Comparison of power and etticiency at

over gate condition between 100~ and

So dratt tube tlow area

Figure 22 - Comparison in variation ot apec1t1c

speed between 100 and 75~ dratt tube

tlow area

50

45

20

-bull - 1--shy40

bull J-~ 30

~ ex

~ 20

~~ ~ -)q

I

~ - _

- -

10~ OF DRAFT TUBE FL(Jif AREA

CONSTANT HEAD OF 8l FEST10

POIER OUTPUT EFFICIENCY SPECIFIC SPEED

0 ~--------------_--------~------~------~ 400 600 800 1000 1200 1400

TURBINE SPEED (RPM)

Figure 17 - Turbine Char~cteristics with 100 Draft Tube Flow Area

50

46

-bulllle

~ 7 ~ OF DRAFt TUBE FLOW AREA

0 -~~-rl C05STAMT BEAD OF 81 mET 1J~

POIER OOTPUT ---+- ---o ~_H EFFICIDCY ~ I shy

bull ql SPECIFIC SPEKD - ~ -

bull ~ J 10 L rmiddotr- r- -

bullz- I

~~ 30 ~~--~----~~-

20 ~ ~ middot-shy

26

~~ 25

~0 ~r-----i (

Tbull -bullshy

400 600 800 1000 1200 1400

TURBINE SPEED (R PK )

Figure 18 -Turbine Characteristics with 75 Draft Tube Flow Area

47

EFFICIENCY 60

1-----shy

-~ 50~--~--~~-~middot middot middot middot r~-~----~~~~---4~-r~-~~gtt

II

POWER~ J ~ bull bull

u I

sH

40~------+-------+---- -~~--~~-~~~~

~----~rl 1 bull

I

I

0~--------------~------_------~--------

~ -OVER GATE CONDITION

COIJSTANT HEAD OF 81 FEET

0 o 10~ DRAFt TUBE

_-- _ 7~ DRAFT TUBamp FLON AREA II

10_~-----+--------r-------r----~~

400 600 800 1000 1200 1400

TURBINE SPEED (RPM)

Figure 19 middot - Comparison between 75 and 100 Draft Tube Flow Areas of Power and Efficiency at Over Gate Conshydition

48

t

bull --4 r ~- ~ middot~

70 1-----------+-~~~~~+middot ~ ~~ middot middot -~~--~~--------~~----~-+1

-~-

Atbull bull

lla-

60

amp0

40

20

10

oampOO

t _ - - ~-+- - -~-

l2 GATB COJIDITIOJJ

COJISTABT HJW) OF 81 JBET

o 0 lOQ( DRAFl TUB8 FLOI AREA

e-- - e 75 DRAFT TUBE FLOW AREA

800 1000

- r-

~

TURBIbull SPBIID (RPII)

Figure 20 - Comparison between 75 and 100 Draft Tube Flow Areas of Power and Efficiency at Half Gate Conshydition

49

60

50

-40

bull 30

IIQbull

20

10

0

400

- t - ~

EFFICIENCY

_J bull - bull bull

~ r r middot t -+ shy L -t -

OVER GAD COliDITIOI

CONSTABT BEAD OF 8l FBB

o o 10~ DRAFt TUBE FLOI ADA middot--- 5~ DRAF TUBE FLQPi AREA

600 800 1000 1200

Figure 21 -Comparison between 50~ and 100~ Draft Tube Flow Areas of Power and Efficiency at Ove~ Gate Conshydition

50

25

20

15

10

0

Figure 22

~- T -4 -t- -l --~-

t-~ I

middot --~- t ~---- _ __ _ + --

----~- --r-- --

~-=J-~-=-~ -==~ _ ~- -- ---f---1 - shy

CONSTANT HEAD OF 81 FEBT

o--o 1~ DRAFT TUBE FLltll AREA

75C DRMT TUBK FLCIJ AREAmiddot--middot-middot 600 800 1000

TURBINE SPEED (RPK)

Comparison of Specific Speeds for 75 and 100 Draft Tube Flow Areas

51

B Discussion 2 Result

Consideration of Figures 17 and 18 indicates the

overall eftioi ncy pattern or hill is significantly or

rounded for the 7$~ flow area than for the 100~ flow area

bia implies a greateP efficiency is possible at speeds

leas than or greater than design speed with an insert in

the draft tube However the muilDum efficiency is lemiddotas

Direct comparison at over gate conditions is made in

Figure 19 ~e same general trend is noted tor both the

etticiency and power curves for the 7$~ flow area case

The eurves show higher values at overspeed than do the

correaponding cWvea for the 100 flow area case It ia

not clear whether the curves have been shifted by the dratt

tube constriction or whether the curves simply bulge past

the normal curves at both overspeed and underspeed condishy

tions The power curves apparently peak near the aeme

point bullalthough maximum power is still obtained with the

normal draft tube area

For the comparison at halt gate operation shown in

Figure 20 a general improvement has apparently been made

by restriction of the draft tube flow area At every speed

the etticienoy and the power is greater for the restricted

tlow case The two ett1o1ency curves and two power curvea

are practically parallel throughout the speed range ot

teat

As the flou aroa i e decreased still farther a s1gn1

ticant change appears Reterr1ng to Figllle 211 tor the $0

flow area curves it a obvious that exit losses have

become excessive at the overgate condition because the

efficiency and power are everywhere leas than tor the case

of normal draf t tube area

Earlier it was pointed out t hat 1t the r esult s 1nd1bull

eated an increase in both power and ef tieiency- t hen it

could be assumed tha t the additional los s i ntroduced with

the draft tube insert is less than the diminished losses

due to leas shock losa and water passage losses For the

places where both the efficiency and power have been

increased we can assume that the insert has improved turshy

bine performance

For the places where the power haa been decreased

nothing can be said as to the elimination of ampbock loss

because the new lose present with the drat tube insert has

overshadowed any gains in eftecti Ve head upatJ-eam of the

insert

Near the peak of the efficiency hill howeve~ it may

be pointed out t hat shock loaa ie a minimum with a normal

draft tube and the insert merely adds an additional loss

with the resultant decrease in maximum efficiency tor the

7$~ flow area case

Perhaps the most s1gn1ticant set of eurves is shown aa

53

Figure 22 In this graph values of specific speed tor the

75 and 100~ flow area cases for both over gate and one

halt gate openings are plotted against turbine speed At

every speed and both gate openings the value ot specific

speed for th 75~ flow area case is greater than that for

the 100 t1ow area ease

Since the head is a constant for both situations this

may be interpreted in either of two ways trom equation

(11)

(1) For the same turbine apeed restriction of the

draft tube t1ow area resulted in greater turbine power

(2) For the same power amputput the turbine with 75~

draft tube flow area operated at a greater speed than did

the one with 100 flow area

Since the required diameter of a turbine varies

inversely with the speed the second interpretation could

be stated such that a smaller turbine could be used to

develop the same power output

Whether viewed trom the aspect of increased power

greater speed or reduced size the performance of the turshy

bine with reduced draft tube flow area is superior to that

with the nolmal flow are in the draft tube

The curve of specmiddotific speed versus turbine speed for

the so draft tube flow area case at over gate cond1t1ona

was not included in Figure 22 This curve lies below that

for the 100~ flow area c se at all speeds

In elaboration ot the second interpretation of Figure

22 attention is directed to the relative magnitudes ot

increased apee1f1c speed tor the two gate openings Assumbull

ing that the increase in specific speed implies a shift ot

the power curve to the right along the turbine speed scale

the power curve would be shifted more tor tbe halt gate

opening than tor the over gate opening

It thia trend could be extrapolated to the other gate

openings the tendency can be seen tor the line ot beat

speed to rotate toward the line of the operating speed as

illustrated in FigtU-e ) The advantage of this has already

been discussed

This particular turbine has a low specific speed tor a

reaction turbine Aa the rated value of apecitic apeed tor

reaction turbines increases the line ot beat speed departs

even more radically from the line of operating bullpeed It a

test similar to this were conducted on a reaction turbine

ot gleater specific speed it is pJobable t hat the rotation

ot the line of beat apeed would become more p~onounced

The scheme used in th1a teat had two obvious dr wbull

backs The first was the decision to leave all the wicket

gamiddottes installed tor all conditions ot the draft tube

These gates predominated in control of the tlow The

inserts added to the draft tube merely acted as auxiliary

55

contrGla

The aecond drawback was the choice or device to place

in the draft tube The reasons foll selection of this type

of device have been previously mentioned It is to be

anticipated that adaptation ot dratt tube flow control

would result 1n a better device for an actual turbine

installation Such apparatus might take the form of a

pneumatic bladder or a h7drau11oally operated variable

venturi section in the draft tube It is conceivable that

the gate as used in this test might be adapted also

Chapter VII

OONCLtJSIOfS

From the results of this test the following eonolubull

e1ona aa to the effect ot a variable draft tube flow area

on the performance or a r action turbine may be drawn

(1) The effect ot a variable draft tube tlow area 1a

generally favorable upon the operat1Gn ot a reaction turbull

bine because or the tendency tor the line or beat speed to

rotate toward the line ot operation This resulte in

better performance of the turbine at partbullloads

(2) he etf1o1ency eh111 tor the turbine beeomaa JDore

tlat at the top leading to a smaller max1JilWD effic1enc7

but e reater etticieney at other pointe of operation with

the insertion ot an auxiliary control ror the rate ot tlov

in the draft tube

(3) The power output of the turbine will increase at

over speed over gate conditione as well a at part gate

conditions with the proper amount or draft tube eonatr1cbull

tion or flow

(4) It is possible to eliminate at least partially

eddy type shock loss by tho introduction ot flow control

in the draft tube

BIBLIOGRAPBl

1 Addison Herbert A treatise on applied h-draul1cs New York Wiley 1954 724 Pbull

2 Allen o M and I A Winter middot Co111parative testa on experimental draft tubes Tranaact1ons ot the American ociety ot Civil Engineers 87t893bull970 1924

3 Barrows a E Water power engineering 3d ed ew York McGraw-Bill 1943 791 Pbull

Bovet G A Modern trenda in hydraulic turbine design4middot in Europe Tranaactions of the American Society ot Mechanical Engineera 75975bull993 1953bull

s Oreager William P and Joel D Justin Hydroelectrichandbook 2d ed New York Wiley 19$0 1151 Pbull

6 Daily Jamea w Hydraulic machinery Int Hunter Rouses Engineering hydraulics Hew York Wiley 19$0 p 8$8bull99

Daughertybull Robert L Bydraulie turbines ew Yorkbull7middot MoGrav-Hlll 1920 281 Pbull

8 Daugherty Robert L Inveat1gat1on of tne performance ot a reaction turbine ~anaactiona or the American Society ot Civil Engineers 7811270bull1304 1915

9 Davie L M Model and prototype testa Int Trend in hydraulle turbine practice symposium lranaactions ot the American Society ot Civil Engineers 1o63S3middot368 1941

lfJ Doland James J Hydro power engineering Hew Yorkbull Ronald 1954 209 Pbull

11 Gandy Theodore s and Elmer c Schacht Direct curshyrent motor and generator troubles operation and repair New York McGraw-Bill 1911 293 Pbull

12 Gibaon Arnold H Hydraulics and ita applications5th ed London Constable 1952 813 Pbull

58

13 Button s P Component loases in Kaplan turbinebull and The prediction of efficiency from model tests Probull coedings of the Institution or Mechanical Engineers168743-762 1954

14 Knapp R T~ Oavit t1on mechanics and its relation to the d sign or hydraulic equip ent Proceedings or tne Institution ot Mechanical Engineers 166150bull16) 1952

15 Langsdorf Alexander s Principles of direct curHnt mach1nee 5th ed New York r~cGrawbullH1ll 1940 746 Pbull

16 Lsrner Chester w Characteristica of modern hydraubull lie turbines Trans e~ions of the ~~erican Society ot Civil Engineers 66306-386 1910

17 Linsley Ray K Jr and Jobulleph B Franzin1 Eleshyments of hydraulic enginebullring New York McGrawshyBill 19$5 $82 Pbull

18 Mead Daniel w Hydraulic machinery llev York McGraw-Hill 1933 396 Pbull

19 ead Daniel w Water power engineering New York McGrawbullRill 191S 843 Pbull

20 Mockmore Charles A Part gate operation at water turbines Corvallis Oregon State College Department ot Civil Engineering 1933 11 numb leaves (Unpubshylshed typescript)

21 Mockmore Oharles A Flow characteristics in elbow dratt tubes Transactions of the Amez-ican Society ot Civil Engineers 103402middot464bull 1938

22 Moody L F Hydraulic machinery In c v Davis Handbook ot applied hydraulics New York McGrawshyHlll 1942 1082 Pbull

2) Ptau At-nold Hydrbullulie turbine handbook ld ed Milwaukee AllisbullOhalmers ManufactUIing Company 1948 70 Pbull

RheingalUI w J Recent developments in Francis turshybines Mechanical Engineering 74189-196 1952

25 Russell George E Hydraulica 5th ed New York Henry Holt 1942 466 Pbull

26 Safford A and E P- Hamilton American mixed tlow turbine and ita setting Tranampactions or the Amerieal Society of Civil Engineers 851237bull1)56 1922

27 bull Spannhake W1lhe1Dh Problems or modern pump and tur b1ne design Transactions of the American Society of Mechanical Engineers 56e22$-248 1934bull

28 Sutherlandraquo R A Better ethod or representing and middot tudying water turbine performance ~ansaetions ot thmiddote American Society of Mechanical Engineers 68t675bull 686 1946

29 Teats ot five models or draft tubes tor turbines Engineering News-Record Pbull 182-184 Aug 2 1923

30 White w M American hydztaulic turbines Mechanical Engineering S2t390bull39S 1930bull

31 White w M lhe hydraucGne rega1ner1 its developmentand appl1eat1ons 1n hydroelectric plants Meohanlobulll Engineering 43t37Sbull380 1921 middot

32 Winter I A Economic principlebull in designbull Int Trend in hydraulic urbin practice bull a ampoeiumTranaaot1ona ot the American Society ot Civil Engineerslo6332bull3S2 1941

33 Wiel1cenua G F Fluid mechan1ca or turbo-machineryNev York McGraw-Hill 1947 613 Pbull

APPENDICES

c

Appendix A

NOATIOB

A Angle between the absolute velocity vector and the tangent to the rwmer Subscripts 1 and 2 refel to entrance and exit ot the runner blade

B Angle between the relative 1elooity vector and the tangent to the rwmer Subscripta 1 and 2 refer to entrance and ezit or the runner blade

Angle between the tangent to the runner blade tip and the tangent to the runnel- Subscripts 1 and 2 reter to entrance and exit of the rt1rmer bladebull

Blade angle-gate opening conetant defined by equation (1)

e 09erall efficiency

g Gravitational acceleration assumed constant at 322 teet per second per second bull

H Turbine head detined by equation ($)

m Exit loss coeft1e1ent

Turbine speed expressed in revolutions per minute

Turbine speed under a constant head of 81 teet

specitic apeed of the turbine under a constant head ot 81 teet

p Power output in horsepower ot the tvbine

Power output of the turbine Ulder a constant head ot Sl teet

Pl- Pressure head at entrance to the tUlb1new

l1 Peripheral velocity ot the runneP Subacr1pta 1 and 2 refer to entrance and exit ot the JUnllampr blade

62

v Relative velocity reaulting trom the combination ot the absolute water velocity V and the runner periphshyeral velocity u Subscripts 1 and 2 refer to entrance and exit ot the runner blade

v] Relative velocity vector necessary to produce a tanbull gential entry into the runner blades

V Absolute water velocity Subscripts l and 2 refer to entrano and exit ot the runner blade

v2 Velocity head Subscripts 1 and 4 reter to the ~8 entrance to the turbine and the tail~ace wate~

w Unit weight ot water assumed constant at 624 pounda per cubic toot

V Weight rate ot flow in pounds per aeooncl

XX Velocity component ot ahook See Figule 2

Z Elevation head Subscripts 1 and 4 reter to entrance to the turbine and the taibace water surfacebull

Appendix B ORIGINAL DATA-Run

lfwnber

0-4-1 0-4-2 0-4-3 o-4-4 o-4-S o-4-6 0-4-7 0-4-8 0-4-9o-4-lo o-4-11 o-4-12 0-4-13

o-6-1 o-6-2 06-3 o-6-4o-6middotS o-6-6 o-6-7 o-6-8 0-6-9 o--6-lo o-6-11

Speed

rmiddot2middotbullmiddot(1)

336 38$ 451 S$9 620 669 6lt)$ 120 787 860 932

102imiddot109 bull

352 355 443middot 543middot 620 654AJs32

911 1001 1111

~essure Head rt (2)

410 410 416 426 431 43-7 439 44-9 452 467 482 soo $1 bull $

350 351 35middot7 )66 37-9 37-9 392 41 bull 3 43middot3 460 489

Elevation Bead

fjj $7 $7 $7 $7 $7 $7 51 57 5-15858 $8 58 56 56 $6565656 51 575As5a

Velocit Head

flj 07 07 07 06 06 06 06 os 05 os0404 03

09 09 oa o8 o8 os 07 07 06 o~o

Total Head rt ($)

47middot4 4A44 o 489 49-4 soo $02 $11 $14 $29 5imiddot45 2 576

41 bull $ 416 421 430 44middot3 44middot3 456 47-7 496 523551

Plow

lbtjec

326 324middot317 311 306 30029middot28 middotmiddot middot 386 275middot260 240 218

359 36~35 bull 349 345middot 339 330 318 300 273 240

Line Potential

vyqjbull 1060 1220 ~-0o 1920 2150 2000 2$60 2000 1940 18)015io11 o

1000 1100 139bull5 1760 1925 16$0 1620 1610 1540 1330 870

Line Current

amlscs 960 900 830 740 730655 70bull 0 530 660 600 5imiddot54 6 )60

982 930 860 780 ~3-545

79-5 74-5 670 560 370

P

Appendix B ORIGINAL DATA (Continued)

Run Number

Speed

Pbulltmiddotbullmiddot )

leasure Head ft(2

Elevation Head tt(J)

Velocity He-dfmiddotj

Total Bead tt($

Flow

lbstsec( )

Line Potential vo~ta( )

Line Current

amjs (sect

0bulllt)-1 0-9-2

3ll6 398

28o ~~1

$6 56

1o 10

346 347

390 365

1ooo 1190

aao 835

0-9-3 0-9-4 o-9-S

472 565 632

292 305 312

$6 s6 56

10 o9 o9

)$8 J7~o 37~7

381376 37o

1)6614oo 141o

820 ass ass o-9-6 0-9-7 0-9-8 o-9-9 0middot9-10

680 120 762 844 920

)24337346 366 390

56 $6 56 57 $7

09 os o8 oa 07

)89401 410 431454

367~ 357348 34o 322

1400 1J6o l36o 1310 1170

843 820 7957So 67~0

0-9-ll 0-912

1001 1100

41 bull 7 45-3

s 7 6~0

06 os 480 $18

299 268

980 65$

560 36~5

1-4-1 1-4-21-4-l1-4shy1-4-5 1-4-6 l-4-7 1 4-8 1-4-9 1-4-10 1middot4-ll 1-4bull12

354middot452 562 62q 674shy102 752 760- 863 932

1022 1100-

)82389 4014oa 416 41--7 423 428 44-2 45-7 486 49-2

51S757 51 5-7 5middot15zs sa $8 58 59

07 07 06 06 06 06 06 os o bull o 04 o J

446 45-)46middot4 471 ti7-9480 q86 491505 $19 548 55-4

)28 320 311 306 300 295 291 286 269 2582iimiddot21 bull

1080 14Lo 1550 153-5 1470 141-0 1385 1310 1310 1230 1120 855

970855 875 91-0 94~0 975 966 995 860 77-S 610 4fo

0 ~

Appendix B ORIGINAL DATA (Contirmed)-Run Speed Pressure Elevation Velocity Total Flow Line Line

Number Head Head Head had Potential Current rtjjmbull t~ bttec vyfs am~a12) ( ) ti fli 8

1-6-l $6 33$ $6 0bull9 400 364 1100 93 0 1-6-2 41 34laquo2 $6 oa 406 JS7middot iios a5s l-6-3 500 3~0 5bull6 os 356 1 1 o aos 41middot~1-6~4 35bull4 5-6 oa 41middot 352 16~0 82 0 5~1-6-5 5 bull 36_2 Sbull6 08 42bull6 349middot 161 ~ 0 86~0 1-6-6 622 366 $6 oe 43bull0 345middot 158 0 88~$ 16-A 649bull 37bull1 56 os 43-S 342middot 1570 895 1~- 386 57 07 46-0 192 ) 125A44 333middot 1-6-9 3) 404 5middot1 07 468 317 1620 675 1610 911 42-4 5-7 o6 48-7 298 168 0 61 0 1-6-11 999 451 56 os Sl ll 276 ~2-0 530 1-612 1115 485 58 04 54middot7 238 90 )3 0

1middot9-l 355 279 56 10 )45 385 1040 870 1-9-2 399 28J $6 10 )49 38$ 1140 86 5 l-9-3 ~ ao 291 56 ~0 35middot1 J8J_ JJ6o 815 1bull9-4 579 303 56 09 )68 375middot J4JO 830 l-9bullS 40- 313 )6 09 31middot8 370- 1460 82~0 1-9bull6 679 2) 56 09 3 bull8 364middot 1670 710 l-9-7 682 319 56 o9 384 ) 62 1460 79 5 l-9-8 724 33middot5 56 o8 399 3$6 bull 1480 76 -5 1-9-9 762 34middot3 $6 0 bull 8 407 )48 14910 13middotS 1-9-10 833middot )60 5middot7 os 42$ 339 144$ 686 1-9-ll 926 39middot1 5-7 07 455 318 1290 600 1-9-12 1000 41middot3 0-6 476 298 1115 510$ ~ 1middot9-13 1105 452 s o4 $14 2$6 710 )10

~

Appendix Bt ORIGDIAL J (Continued)

Run Speed Pressure Elevation Velocity Total Plow Line Line Number Head ltead Head jlamp$d P()ten~ibulll Current

r~~~m ft ft lbs~seo voltattj rgj twimiddot t 1 t2gt lt3 ou t ( rt

2-9-1 384 289 S 6 10 35 5 1400 1170 810 2-9-2 443middot 29$ $6 ltimiddot9 360 379middot 11(0 87$ 2-9-J 536 30bull 3 sc 09 )68 374middot 1)40 84 bull) 2-9-4 571 306 $6 09 3~1 372 120bull 0 955 2-9-5 623 316 S6 09 J l )6S UJSo 77$ 2bull9-6 669 327 S6 09 )92 )61 1240 905 2-9bull7 712 )39 56 os 40-3 351 12(0 86 bull0 2-9-8 ~5$~ J48 56 oa 412 348 1290 81 bull ) 2-9-9 04 )63 56 oa 42-7 339 12ltJO 76$ 2middotmiddot9-10 8$2 376 5middot1 07 440 33~- ~ o 710 2-9-11 955 394 5-1 o6 457 300 1100 506 2middot9-12 1000 421 $7 06 48middoti 295 1020 $18 2-9bull13 110~ 463 56 05 $2 267 620 3~0

oshy0

Appendix Gt CALCULATED DAgA

Turbine Run Generator Generator Turbine Turbine Efficiency Turbine Turbine Specit1c

Number OutputKWlt21

Loa~Jes KWlol

Outut K bull (H)

Input RP 12)

middot Percentlt13gt

Speed r~Jmiddot(

0ltput HP ~1

Speed r-m

( 6) middot

o-4-1 0middot4-2 0-4-3 0-4-4 0-4-5 0-4-6 O-qmiddot7o-4-8o-4-9 0-4bull10 0-4-11 o-4-12

1018 1o9a 1220 1)62J40214oa1J4oo 1357 1320 1164 997 718

046 o59 071 092 096 1071oo 134 104 100 109 107

14261sso 17)01948 2008 20322011 1999 19 09 1708 14-84 11o6

281279 27-7 276 215 273271 268 268 26h 258 24-5

soa 555 62$ 705 7)1145 742 74-6714645 51s 45-1

440 sos 585 720 195 sso sao 9$$ 985

1065 1135middot 1230

318 357 319 416 422 419412 39middot9 378 324 260 191

102 12bull4 148 191 21bull 3 22o 233 249 24924middot9 238 221

0-4middot13 418 104 699 228 306 1300 117 18)

o-6-1 982 045 1376 271 $08 496 376 124 o-6-2 o-6-3 G-6-4o-6-5 0-6-6

1023 1200 13 73 J415 139h

051 0middot66 oaa ()bull 96 088

14-39 1696 1958 2026 1986

276 27middot4 273 278 274

$20 61 8 717 7)0726

q95615745 8)5685

390 ll5middot3 sos soo 490

127 170 218 243 2$$

o-6-7 o-6-8 o-6-9o-6-lo

1288 1199 1032 7-45

o9o 094 09$ 096

1846 1733 1511 1128

274 276 271 260

67S 629559 43middot4

980 1085 1165 1245shy

436 )83316 21bull 7

266 276 270 239

0-6-11 322 1oo 566 2141 2JS 1350 101 177 0 --4

Appendix C CALCULATED DAlA ( Continued)-Run

Number Generator Generator

Out2ut Losaes xw LW- 12gt (lO)

Turbine Out2ut

ltPlJ

Turbine Inat lfP Jig)

Etpound1e1ency

PireentDl

Turbine Sed x-~m( 1

Turbine OutEut RPJl)

Turbine Specific

SeeedrIbullntbull

( 6)

o-9middot1 0-9-2 0-9-3 o-lt)-4 09-$ 0bull9-6 0-9-7 0-9-8 0-9-9 0-9-10 o-9-11 0-9-12

aao 994

111$ 1197 1206 1180 11)21081 982 784 5-49 2)9

0middot45oss o6$ 070 07$ 0-77 (l77 or~ o s06o 8 096

123~ 1402 1$80 1698 17bulllS 168$ 16bull18 ~middot5430 1151 a~J4 9

24middotgt24middot3248 25~25 260 260 259 267 266 26middot1 2S2

sos 577 63-7 671 676 650 621 60036J4

327 178

$) 610AlO 3$

92S 980

102$ 1070 1157middot 1230 1300 137Smiddot

44middot4 soo 523 ssomiddot 540so6 46-5 432 368 274 18~8

J46 176 21-1 255 2802s_A 28 289 288 265 231 168

1-4-1 1-4middot2 1-4-3 1-4-4 1-4-5 1-4-6 1-4-7 1-J-8 1-4~9 1-4-10 1-4-11 1-4-12

10bull48 1231 13-S6 1397 1)821375 1))8 1303 1127 953 683) 51

048 067 o7A07 0 bull79 oa1 oss o bullao osa 0lt)0 096 099

J468 1740 1921 1978 1958 19$1 1911 lSSi162 1)98 1045

603

266 264 262 262 261 2512$7 2$6 24middot7 24-3 233 217

551 660 13middot3155 75-6 7~-97 middot4 72$ 67 51middotJ 44middot9 21middot1

475 605 A4220

875middot 910 970_

1000 1090bull 1166 1243 1330

5816

44middot444middot5 430 427 412 392 329 273 188 l0-7

117 101 204 22$ 2)7245 2562sa 257251 222 179

a-C))

Appendix Ct CALCULATED -DATA ( Ocntinued)

1-6middot1 1023 o$2 14-41 26S 505 41~6 26~

54middot5 13middot3l-6-2 1201 067 1boo 625 47-9 17shy~middot41-6bull3 1296 oA9 1 middot43 26 9 700 so5 20bull 4 l-6-4 l3j5 o 0 19~09 268 71bull3 A5o 514 222 1-6-5 1) 5 o81 19(gt4 271 725 51-5 238 l-66 1398 081 198) 27-0 736 8 S13 252~-middot l-6j 1405 083 199i 211 733 885 $middot06 2$9 l-6 13middot9~ 103 2amp 0 279 71 8 985~ 467 ~-69 1228 1 bull 02 17-SS 270 661 109$ 407 ~3~ l-6bull10 1025 100 lSll 26i 573 1175middot 27~S32middot~l-ampu 153 1-00 llft3 26 444 1270 22 24bull8 1bull6-12 294 100 52a 231 22 3 1360 95 172

1-9bull1 904 048 1275 2J4Z $28 S4$ 459 1$2 1-92 98$ oss 13-92 24middot4 57-0 6JO 49bull1 176 1-9middot3 1110 066 1$76 24middot9 63middot4 I2o 536 21-7 l--9-4 1187 072 1685 251 66$ 5 $$ bull 0 261 1middot9-5 llltJ7 1710 25middot4 67-3 93$ 536 28~20-671middot9-6 1186 o 8 1708 25-7 67) 980 $15 2691-9- 1161 oBo 1660 2$middot3 6$6 990 508 29-1 l~- ll-32 oB) 16sect0 2$8 632 1030 471 291 1-9bull9 109$ oa5 2$7 614 1075 29S~middot 0 4imiddot41-9-10 9~91 oas 262 S$1 1150~ 3 o 292 1-9-11 o9o u57 12JiO 21gt 26-77middot74

-45 26sect ~middot91-912 $69 091 sas 25 middot3 1)0$ 196 2J-8 1-9-1) 220 098 426 2)9 178 1390middot 84 16 6

0 0

Appendx C CALCULATED DATA (Continued)

Turbine Run Generator Generator lurbine Turbine Eft1e1eney Turbine lurbine Spee1f1c

Number Output Losses Outit Input Speed Output SPed middot k_-V KW R _ H_bull_P Percent r Thm HP rpm_ (9) tlo) 11) middot (12 _) (lJI ( ) (1$ (14)

2-9-1 9--46 055 1)62 258 528 580 164 2-9-2 1024 056 248 58 4 665 4 9 191iimiddot48 4~middot0 2-9-3 1132 067 05 2$0 641 795 52q 237 2-9-4 1148 065 1027 2$1 -~8 845 525 252 2-9-5 11 77 oso 16-83 253 6 910~ 522 270 2-9 6 1122 071 1600 251 622 960 47-5 2722-9-A 1092 015 1562 257 608 1010 445 2z12bull9- 1052 079 1514 261 580 1060 41middot7 2 2 2middot9-9 986 o82 ]429 26) 542 1105 372 277 2-9-10 915 086 1340 268 500 1160 334 27-6 2-9-11 638 087 972 254 )81 1270~ 229 250 2-9-12 )28 090 828 259 )19 1295 179 226 2-9-13 192 094 383 2$ 6 150 1370 7 3 152

-3 0

Page 20: The Effect of A Variable Draft Tube Flow Area on the

13

vector is at right angles to the tangent to the runnerbull

ie the angle A2 1e ninety degree bull It ia to be expected

that this condition will be tultilled near the design con~

d1t1ons ot the ~bine

Current design praetiee 1 to have a small component

ot v2 in th$ direction of turbine rotation at rated condibull

tion$ ltS p 938)

For a constant turbine speed the d1seharg or exit

loss is ess nti lly a constant

For a constant gate opening the exit lo s curve is

aptrroximately a symmetrical pa~abola with ita vert x the

point or minimum loss located at a slightly lowe~ speed

th n the turbine rated speed (7 Pbull 79)

Chapter III

PROPOSAL OP ALlERMAlE MFTBO 0 CO TROL-A lz ~ Location 2 Control

Thua tar only practice and theoretical aspects appemiddotrbull

taining to present day turbinea have been d1acuaaed It

haa been presented that control over the ~bine ia ezerbull

oiaed b y manipulation of the wicket gatea located 11101led1bull

ately preceding the runner These gate - upon rotation

modify both the magn1tu4e and the direction ot the entering

velocit7 Moreover it has be n shown that a simultaneous

change in these two variables leads to inefficient operabull

tion by the introduction of shock loss he farther the

point of operation a from the rated conditione the more

aerioua ia the ahock loss encountered

Any attempt to better turbine pertorance at other

than rated conditione and tbne flatten the top ot the

etticieney hill8 must concentrate upon the lessening ot

the ahock loaa It 1a a aumed that 1 provement in the

scroll case gates and runners would lequ1re sueh pertecbull

tion 1n machine work and metal$ as to be prohibitively

expensive

It ie surmised that any move to elblinate eYen parbull

tially the shock loss would require separate control ovel

l$

the flow and gate exit angle Since it is improbable that

d1~ect1on could be controlled at any location other than

where the gatea are situated in current turbines it will

be assumed that guide vanes will be necessary regardlesa or the method used to control the rate of flow

The primary purpose ot th se guide vanes 1s that or control over the direction ot the incoming water They

should be free to rotate in much the same manner as ordibull

nary wicket gates in order to exercise control over th

turbine speed

If the rate ot tlov is to be controlled elsewhere it

must be modified either in the penstock or the draft tube

Devices that could be used are standard valves gates

variable orifices variable venturi sections and associated

flow regulating schemes

Alauming it were decided to locate such a device upbull

stream of the turbine it would be necessary to allow disbull

tance tor the flow picture to become reestablished prior to

entry to the turbine A contused flow making transit of

the turbine passages would only contribute additional loesbull

ea Such a distance allowance would be perbapa 20 to So

diameters (2$ Pbull 119-123) In large penstocka th1a would

repreaent a considerable distance Which from the viewbull

points ot convenience and control would be undesirable

Attempts to ascertain the effect or additional tlov

16

reduc ion at the wicket gatctsmiddot wae ade 1n the lfadraulioe middot

Laboratory of Oregon St middot te College in 1933 (20) Three

d1tterent thode ot reducins the tlow were t~ied

(l) Locking in the cloeed position pairs or wicket

gatea located opposite to eaeh o~er on the -periphery ot

the wheel

(2) Locking adjacent gates in an open position by

inserting blocks of wood between them and

()) Suocess1vely looking adjacent gates in the closed

position

The results indicated a arked reduction in both power

and efficiency when compared to the curves tor normal gate

operation However it was demonstrated that it was poae1bull

ble to ahitt the power and tfieiency curve ill relation to

turbine apeed lbis important feature will be diacussed

later

ihe main conclusion of the investigation was that conbull

trol by the conyent1onal wick t gates was auper1or to other

methode egtt control exercised at the gates the aelvebullbull

It would app$ar that the bebullt location tor flow conshy

trol would be in the draft tube since none of the objecbull

tiona prev1ously mentioned wou~d eziat there

As bas been stated previously the sole object or the

17

18

turbine is to produce power as etfic1ently as possible

The equation tor the power output of a turbine () Pbull 227)

PaWHe HP (4)55o bull bull Assuming the head 1a constant and a g te located in

the draft tube decreases bhe rate ot flow the power eu

only be increased if the etticiency increases

The ettective head Gn the turbine 1s conventionally

d r1ned as the difference between the auma ot the elevashy

tion head pressure head and velocity head at the entrance

to the turbine casing and the tailrace ($ Pbull 872)

lt ie recognized that the theoretical treatment ot

shock loss as given is highly approximate and serves only

to dictate certain trenda For example the area at xit

rom the wicket g tea CfUl be measuPed with some exactness

but there exists no guarantee that the wateP particles will

complet-ely fill the apace oz- will exit at the establiahed

g te angle The same can be said of the exit trom the

runner blades AssUIlptiona were implied which would indishy

cate that all water particles passing a given croea section

ampH traveling at the same velocity in the same direction

the e alone are autt1c1ent to show 11m1tationa in a theoretbull

1eal approach to the problem

Assume a turbine with ordinary wicket gates tor oonbull

trol compared gainst the same turbine with a gate in the

18

draft tttbe tor supplampment1ng control or the rate ot rlow

Let it also be assumed that the two turbines are opershy

ating at the same point It 1s desirable to predict relabull

tive performance of the two turbines 1 this point of

operation is such that edd7 s hook loss ot reasonable proshy

portions is present in the fir t turbine

~ tull erteot of the shock loss will be exper1 need

by- the fir t turbine

lhe second turbine will derive certain advantages 11

the gate in the draft tube is adjusted to reduce the tlov

1n the proper amount Since they vary a the square ot

the veloo1t7bull the lossabull in the aeroll case wiomiddotket gate

and runner passages will decx-ease aetet-r1ng to Figure 2 1

it can be seen that a decreased velocity v1 w-ill reduce the

eddy shock losa

The ent loss in the dJtaft tube of the second turbine

will be the sum ot the tr1ct1onal loss and the velocity

head at ex1t The velocity head dissipated will be greater

due to the closing action or the gate but the reduoed

t~ictional loss which ia a tunction ot the rate of tlow1

will partially balance this

It 1a entirely possible that the net reduction in

losses in the second turbine will lead to a greater ettibull

oiency and more power output than 4eYeloped by the first

turbine

19

In Figure 3 the plot ot power output against turbine

speed for Curv A~ represents the typical family of curvea

tor a reaction turbine Th b st sp ed is the locus ot

points connecting maximum eft1oiency at each gate opening

The operating speed is the coZUJtant turbine apeed which

passes through the point ot maximum efC1ciencr of the turbull

bine The plot of turbine efficiency against power output

for Curve A is also ahown

It the turbine with flow regulation in the dratt tube

oan demonstrate superior power and efficiency at part loads

the effect would be the same as a shifting or the power

curves toward the condition shown fop Curve B 11 Thisbull

illustrates th ultimate case of the uperpoait1on of best

and operating speeds It will be noted that the pet-form~

of the turbine ot Ourve Bu 1a better than that of CUrve

A at part loads because of ita ability to sustain a relabull

tively high etticienoy ovel a Wider range of power output

o Reguireaegts tort Test Velitication

It is desired to deterra1ne the effect on the turbine

performance b) the addition of a gate in the dratt tube

Th step in the teit will bet

(1 To determine the power output and efficiency ot

the turbine tor wicket gate settings above and below rated

conditione for a wide range ot speed

20

CURVEAbull

TURBINE SPSBD TURBID SPEKD

POIBR OOTPOl

Figure 3 - Turbine Performance Curves

21

22

(2 peat (l) with the gate installed in the drat

tube

(3) middot Converting middot all data to a constant head compare the

powere and effioiencies at the same wicket gate setting and

turbin speed tor the two cbullses

If the ddition or the gate indicates an improvement

in power output and efficiency and the powe~ curve shifts

to the right along the turbine apeed scale the advantage

ot draft tube con~ol of the flow will hav been demonshy

strated

Chapter IV

A E9J11pment

ih turbine used in this test is lJ 5 1nch Pelton

reaction turbine with a rated output ot 30 horsepower under

a head of 56 feet at a speed ot 720 reYolutiona per minute

Views of this turbine are hovn in Figures S and 6 The

turbine is installed on a concrete pad located over an open

channel in the Hydraulics Laboratory at Oregon State Colshy

lege The date of manufacture of this turbine was 1915

The water was delivered to the turbine from a sump

reservoir by two pumps operating 1n parallel Each pump 1a

an 8 inch Pelton double suction centrifugal pump witb a

rating of l$00 gallons per minute at a head ot 75 teet with

a speed ot 1175 revolutions per minute Tbe inlet tlange

ot tne turbine is $pprox1mately 18 feet above the center

line of the pump

A direct current generator was coupled to the turbine

to receive tne power d veloped as shown in Figures 4 and 7 The generator is a Spr gue Electrodynamometer rated at SS horsepower with a speed range of 7$0 to l$00 revolut1one

per minute The classification is type LO 26A 2)0 volta

Figure 5 - View of Test Turbine

Figure 6 ~ View of Test Turbine

and 149 amperes lbe generator ti ld was aepar tely

excited using direct current from a motor g n r tor ampt

(l$ p 4~8)

The power output of the generator waa dissipated in

the water rheostat (3 p 488-489) shown in Figures 9 and

10 The galvanized tank contain d water ot variable d pth

on an electrode ot cast iron m aauring 1bull x 1 x 1

In the initial installation of the turbine it was

intended that the power output should be measured with a

Prony brak bull For th purpoa68 or this teat it was decided

that the brake was too instable and the generator was

substituted The platform for raising the generator the

nee asary two teet for alignment was built out of available

material In this case heavy laminated wood blocks reiashy

torced with other timbers were used and bolted through the

concrete deck (11 Pbull 36-$7)

Due to the light concrete deck the lack ot mas in

the platform and the slight misalignment in the flexible

coupling ao e vibration waa encountered It seemed to

ncr aae linearly to a maximum at the speed of bout 750

revolutions per minute Above this speed no vibPation was

noticeable The vibration waa not se~ere and does not

appear to have materially affected the test results

26

B Intrumentat1on ~ eaeur1ng Devices

The pressure head at inlet to the turbine vaa meaave4

bymeane ot two )6 inch waterbullmeroury manometerbull connected

in series as shown in Figure 8

The terminal voltage ot the generator vas meaeured by

a laboratory voltDleter with a range to )00 yolta and callbull

brated to within 15 Yolta

The armature current bull and hence the line current was

measured by a laboratory ammeter with a range to 150 amperea

and callbrated to w1 thin o 7S amperes

Tae rate ot tlow was established by weight and time

meaeurementa The weighing ank has a capacity ot 121 000

poundsJ the weight belng indicated by Toledo direct reading

scales Timing was done with a hand atop watch with clivibull

aion ot 02 second

he ~ater level in the tailrace was dete~1ned by a

hook gauge lhie was read to the nearest 001 toot

The turbine and generator speeds were eaaured by a

hand tachometer The technique of almost cont1nuoua readbull

ings of the speed gave an error ot no more than 5 revolubull

tiona per minute

c Operational Procedure

Atter the water level in the aump was checked to

insure an adequate auppl7 the puapa were primed and

27

Figure 7 - Test Generator and Plattorm

Figure middot8- Instrument Board and Field Rheostat

28

started After venting they were valved for operation 1n

parallel

The motor generator set was started to supply the

field current and the circuit breaker was closed Water

wa added to the water rheostat to the level shown in

Figure 10 ~ field current wae minimized by cutting in

all the f ield resistance in the field rheostat of Figure 8

The l2 inch gate valve shown in Figures 5 and 6 waa

slowly opened and the turbine and generator brought up to

speed The 12 inch gat valve and turbine were vented and

the pumps were checked to insure neither had lost ita prime

lhe water rheostat offers very steady load 1f the

water level is essentially constant and the water temperabull

ture 1a fixed () p 488~89) In order to maintain this

constant temperature it was decided not to circulate the

water in the rheostat but rather to allow the water to

boil thua achieving the desired result A standing wave

was set up on the face ot the electrode by the boiling

action but a atable load was eatablished except at very

low water leYels where th11 agitation led to fluctuationa

in the line current

After putting the turbine and generator on the line

maximum power was dissipated in the rheostat by redueing

the turbine speed to between oSO and Soo revolutions per

minute Salt vas added to the rheoetat wat r to increasemiddot

29

Figure 9 - View of Water Rheostat

Figure 10 - View of Water Rheostat

Separate Field ExcitationFrom Motor-Generator set Compound Water-Mercury

---shy

re Manometer

I Q)

~ 0

~

Book Gauge

Open Channel

I

Slap Reservoir

Figure 11 - Wat~r Flow Diagram and Electrical Layout

31

waiting pe~iod ot perhaps an h~ followed

while the boiling point or the water wbulls reacbe4 During

this ti+ne the manometer was vented end eheoked electrical

measur1ng 1nstlUments were connected end the hook gauge was

adjusted tor elevation

It required about two- houtte tor the generator to reach

its normal operating tempe-ratu~e_ After the water in the

rheostat and generator had reached their operating temperabull

turea it was possible to begin the taking of data

The only vaPiable which was controlled wee the turbineshy

generator speed However the upper l1ut1t of safe line

current was slightly over 100 ampJilPampPes and the eireuit

breaker would open when the current reached lOS ~ere bull

Control was exercised by means ot regulating the water

level and salt 1n the water rheo tat and the res1stsnoe of

the tield rheost t~

The etfeet ot each type ot regulation on the three

variables is shown below

Volta Aaperebull Speed

Inc Dec Inc Dee~ Inc Dec

Wa~e1 Level Inc Dec~ X

X X X X

X

Salt Concentration

Inc Dec X

X X X X

X

field Resistance

Inc Dec

X X

X X

X X

32

Jlot all methods gave the ame amount ot change in a

given variable and a period of experiment and trial led to

the following scheme starting the rune with the lowest

turbine speed the water level was high with a high amount

ot salt and the field resistance was cut completely out

Aa it became necessary to increase the speed tor each

aucceasive run either cutting in t he field resistance

decreasing the salt concentration or lowering the Vater

level would produce the desired result However decreasbull

1ng the salt concentration had to be done Without a net

gain in water which led to a tluahing procedure that was

not particularly good because cold water was introduced

which required time to heat to the boiling point Cutting

1n additional field resistance was a good method but th1a

increased the amperage possibly to the point of opening

the circuit breaker Lowering the water level was aatiashy

factol1 until the level got too low causing the current

fluctuation previously mentioned Actually it turned out

that a combination of lowering the water level and cutting

field resistance in would carry the speed from ita minimum

to 1ts maximum value it the proper choice were made each

time the speed waa to be changed At the conclusion of

each aet of runs at a high speed the water level would be

low and the field resistance high

33

TURBINE

PAD AND DECK

TAILRACE

WATER SURFACamp

CONCRETE

DRAFT TU1B INSERTS

7 5( DRAFr TUBE

FLltJI ARIA

5~ DRAFT TUBE

FLOI ARSA

Figure 12 - Sketch of Draft Tube and Test Inserts

34

Figure 13 - View of Draft Tube Insert

Figure 14 - View of Draft Tube Insert

D c __ ~s_middot hedu_le of

A number was assigned to each run The fi~st number

applies to the draft tube tlow areas

1 bull 100~ flow area or 0~ oonatriction

2 - 7S tlow area or 2$ conatr1ct1on

3 SoC flow area or so~ constriction

The second number refers to the wicket gate openings

9 over gate opening

6 bull intermediate gate opening

4 bull one h lt gate opening

The third number 14entif1ea the location of the particular

1Wl in a set ot rona made at a given dratt tube tlow area

and wicket gate opening

fnua run number 1bull4bull10 would identity this as the

tenth run ot a set made at halt gate with 75 ot the draft

tube t1ow area

Rune w re made tor a g1yen dratt tube condition

Firat tor tull 41-aft tube flow area seta ot rune were

made for the overgate halt gate and intermediate gate

conditione An insert was placed in t he draft tube and

rune based on the same gate conditions were made tor the

7S~ draft tube flow area case The insert was then changed

to allow only $~ draft tube flow area

The inserts are sketched 1n Figure 12 and photographed

ln Flgurea 13 and 14 They oonaisted of circula~ segments

36

or l2 ineh plywood mount 4 on wooden legs 10 inches high

The 1nse7te were placed in position and secured by th use

ot a-clamps on the legs and the outside ot the bottom of

the draft tube The obvious disadvantage to this method

waa the neoeasity tor draining the water from the tailrace

tor a change ot 1naert The advantage vas of course the

simplicity ot design and construction

Chapter V

DATA-A Original Data

The normal data-taking crew consisted or two men

Assuming adjustments having been made to secure a certain

turbine speed (aee section on Operational Procedure) one

man would take semi-continuous speed readings with the hand

tachometer until a state or rotational equilibrium was

reached This could be only a period or two minutes up to

ten or tifteen minutes As soon as steady speed was

assured the data taking would begin The second man went

to the weighing tank Where a minimum ot three weighingamp

were made The requirement was to get three consecutive

readings such that the ditterence between tbe smallest and

largest time did not exceed 04 seconds The time to

collect a given weight ot water was then assumed to be the

arithmetic average of the three times He then went to the

hook gauge determined the hook elevation and then

recorded the data on the data sheets The first man meanshy

while had taken readings of the line voltage line current

and manometers and checked the turbine speed by multiple

readings During the length of the run all values were

38

checked to determine mean values for recording

The minimum length of one run was about five minutes

If one or more measure ants tended to drift during the run

all values wer discarded and a new run began as soon aa

qu111br1um was stabl1shedo

B -0-al_e_u_l_a_t--d Data

The h d on the tu~bine 1 defined by

($)

The maxtmwm velocity V4 was equal to about o8 tampet per

secon4 which makes it a negligible quantity when converted

into velocity head

An engineerbulla level was used to deterine the d1ffePshy

ence 1n elevation between the compound water-mercury manoshy

meter and the hook gauge Using this value the equation

for turbine bead becomes

where z4 is the hook gauge reading

The rate of flow 1 cent

w weight or water collected average time to collect

The inlet velocity v1 vas calculated by dividing the

weight rate or flow by the specific weight of water and the

)9

area ot ~e inlet pipe This was equivalent to dividing

the weight rate of flow by 490 Then the power input to the turbine is equal to

WHpin rri

10 (6)

Also

(P ~ut) Turbine

(P out) + Generator

(P lost) Generator

The power output of the generator is simplJ the

produot ot the terminal voltage and the armature (line)

curPent The power lost in the generator can be subdivided

into copper losses and stray power losses lo evaluate

these cunes based on losses of an identical generator

11leampsured by the Department ot Mechanical Engineering were

used The loss curves are reppoduced in part in Figures

15 and 16

Determination ot generator losses proceeds as tollowau

(1) From Figure 15 detem1ne the vo1tage drop in the

armature circuit using the temperatures of 1220 F and the

meaaured current

(2) The induced voltage is t~e sum of the terminal

voltage and the voltage drop 1n the armature circuit

() Entering the induced voltage and the turbine speed

into Figure 16 the stray power loss can be determined

(4) The copper lose can be evaluated from Figure 1$

using the measured current and the temperatlll-e of 1220 P

40

25 ~------~--------~--------~------~

U) -U) - 20

f-4 ~

-~ -gt 0

0

VOLTAGE DROP

~ - i -

- bullbullbull bull - -middot-middot -+ ~- + -t--+ ~ - ~ middotbull ~-~ middott- -+----- _ -4 middotmiddot- --~-+-t---r~~ ~--+t-t- - ---t-c-++~-ulf--

0 50 75 100

Figure 15 - Curves of Generator Voltage Drop and Copper Loss

41

1200

1000

800

600

800

0

0

~-

middot--~ 1shy --1 + bull l

100

I -

150 200

IIDOOED VOLTAGB (VOLTS)

Figure 16 - Curves of Generator Stray Power Loss

_ j

-bullshy -L---- shy middot -shy

250

- r

42

(5) The generator los os equal the sum of the eopp r

loss and stray power loss

~e efficiency or the turbine is taken as

etticiency u e =P out (8)Pin

~ample pound Determ1n1gg turbine Power Output

The following data are taken trom that ot Run 1-9-1

Line voltage 1040 volts Line current 870 amperesSpeed 355 revolutions per minute

The induced voltage 1a determined as follows

Line voltage 1040

Voltage drop 90 using Figure 15 with line current of 870 amperes and temperature ot 122 degrees)

Induced Toltage 1130 volta

The power output of the turbine is determined as follows

Generator output 90$0 (line voltage z line current)

Oopper loss 7 (using Figure 15 with line current of 870 amperes and temperatUe or 122 degrees)

Stray power lose 470 (using Figure 16 with speed ot 355 revolutions per miDUte and induced voltage or 1130 volts)

Turbine power output 9527 vatta

or turbine power output 1s 12z2 horsepower

43

The conversion of the calculated data to a constant

head is based on the conventional assumption of constant

efficiency regardless of turbine head For a constant head

ot 81 teet a purely arbitrary figure the tollowing relashy

tionships are ass1lJiled to be true

I ____L (9) (i)l72

(10)

For these two values the specific a peed may be combull

putedt

N t Jt VPt (11)8 243

Chapter VI

~RESULTS

A -Pr_e_ae_n_t_a_t_t_o~n g Reaultbull

Graphical presentation ot the results ot this te1t

are given as follows

Figure 17 -Turbine characteristics with 100~ dratt

tuba 1low area

Figure 18 - Turbine characteristics with 7S dratt

tube tlow area

Figure 19 bull Comparison ot power and etticiency at

over gate conditions between 100 and

75~ draft tube flow area

Figure 20 bull COZQparison of power and ettic1ency at

halt gate conditions between 100~ and

7S~ draft tube flow area

Figure 21 bull Comparison of power and etticiency at

over gate condition between 100~ and

So dratt tube tlow area

Figure 22 - Comparison in variation ot apec1t1c

speed between 100 and 75~ dratt tube

tlow area

50

45

20

-bull - 1--shy40

bull J-~ 30

~ ex

~ 20

~~ ~ -)q

I

~ - _

- -

10~ OF DRAFT TUBE FL(Jif AREA

CONSTANT HEAD OF 8l FEST10

POIER OUTPUT EFFICIENCY SPECIFIC SPEED

0 ~--------------_--------~------~------~ 400 600 800 1000 1200 1400

TURBINE SPEED (RPM)

Figure 17 - Turbine Char~cteristics with 100 Draft Tube Flow Area

50

46

-bulllle

~ 7 ~ OF DRAFt TUBE FLOW AREA

0 -~~-rl C05STAMT BEAD OF 81 mET 1J~

POIER OOTPUT ---+- ---o ~_H EFFICIDCY ~ I shy

bull ql SPECIFIC SPEKD - ~ -

bull ~ J 10 L rmiddotr- r- -

bullz- I

~~ 30 ~~--~----~~-

20 ~ ~ middot-shy

26

~~ 25

~0 ~r-----i (

Tbull -bullshy

400 600 800 1000 1200 1400

TURBINE SPEED (R PK )

Figure 18 -Turbine Characteristics with 75 Draft Tube Flow Area

47

EFFICIENCY 60

1-----shy

-~ 50~--~--~~-~middot middot middot middot r~-~----~~~~---4~-r~-~~gtt

II

POWER~ J ~ bull bull

u I

sH

40~------+-------+---- -~~--~~-~~~~

~----~rl 1 bull

I

I

0~--------------~------_------~--------

~ -OVER GATE CONDITION

COIJSTANT HEAD OF 81 FEET

0 o 10~ DRAFt TUBE

_-- _ 7~ DRAFT TUBamp FLON AREA II

10_~-----+--------r-------r----~~

400 600 800 1000 1200 1400

TURBINE SPEED (RPM)

Figure 19 middot - Comparison between 75 and 100 Draft Tube Flow Areas of Power and Efficiency at Over Gate Conshydition

48

t

bull --4 r ~- ~ middot~

70 1-----------+-~~~~~+middot ~ ~~ middot middot -~~--~~--------~~----~-+1

-~-

Atbull bull

lla-

60

amp0

40

20

10

oampOO

t _ - - ~-+- - -~-

l2 GATB COJIDITIOJJ

COJISTABT HJW) OF 81 JBET

o 0 lOQ( DRAFl TUB8 FLOI AREA

e-- - e 75 DRAFT TUBE FLOW AREA

800 1000

- r-

~

TURBIbull SPBIID (RPII)

Figure 20 - Comparison between 75 and 100 Draft Tube Flow Areas of Power and Efficiency at Half Gate Conshydition

49

60

50

-40

bull 30

IIQbull

20

10

0

400

- t - ~

EFFICIENCY

_J bull - bull bull

~ r r middot t -+ shy L -t -

OVER GAD COliDITIOI

CONSTABT BEAD OF 8l FBB

o o 10~ DRAFt TUBE FLOI ADA middot--- 5~ DRAF TUBE FLQPi AREA

600 800 1000 1200

Figure 21 -Comparison between 50~ and 100~ Draft Tube Flow Areas of Power and Efficiency at Ove~ Gate Conshydition

50

25

20

15

10

0

Figure 22

~- T -4 -t- -l --~-

t-~ I

middot --~- t ~---- _ __ _ + --

----~- --r-- --

~-=J-~-=-~ -==~ _ ~- -- ---f---1 - shy

CONSTANT HEAD OF 81 FEBT

o--o 1~ DRAFT TUBE FLltll AREA

75C DRMT TUBK FLCIJ AREAmiddot--middot-middot 600 800 1000

TURBINE SPEED (RPK)

Comparison of Specific Speeds for 75 and 100 Draft Tube Flow Areas

51

B Discussion 2 Result

Consideration of Figures 17 and 18 indicates the

overall eftioi ncy pattern or hill is significantly or

rounded for the 7$~ flow area than for the 100~ flow area

bia implies a greateP efficiency is possible at speeds

leas than or greater than design speed with an insert in

the draft tube However the muilDum efficiency is lemiddotas

Direct comparison at over gate conditions is made in

Figure 19 ~e same general trend is noted tor both the

etticiency and power curves for the 7$~ flow area case

The eurves show higher values at overspeed than do the

correaponding cWvea for the 100 flow area case It ia

not clear whether the curves have been shifted by the dratt

tube constriction or whether the curves simply bulge past

the normal curves at both overspeed and underspeed condishy

tions The power curves apparently peak near the aeme

point bullalthough maximum power is still obtained with the

normal draft tube area

For the comparison at halt gate operation shown in

Figure 20 a general improvement has apparently been made

by restriction of the draft tube flow area At every speed

the etticienoy and the power is greater for the restricted

tlow case The two ett1o1ency curves and two power curvea

are practically parallel throughout the speed range ot

teat

As the flou aroa i e decreased still farther a s1gn1

ticant change appears Reterr1ng to Figllle 211 tor the $0

flow area curves it a obvious that exit losses have

become excessive at the overgate condition because the

efficiency and power are everywhere leas than tor the case

of normal draf t tube area

Earlier it was pointed out t hat 1t the r esult s 1nd1bull

eated an increase in both power and ef tieiency- t hen it

could be assumed tha t the additional los s i ntroduced with

the draft tube insert is less than the diminished losses

due to leas shock losa and water passage losses For the

places where both the efficiency and power have been

increased we can assume that the insert has improved turshy

bine performance

For the places where the power haa been decreased

nothing can be said as to the elimination of ampbock loss

because the new lose present with the drat tube insert has

overshadowed any gains in eftecti Ve head upatJ-eam of the

insert

Near the peak of the efficiency hill howeve~ it may

be pointed out t hat shock loaa ie a minimum with a normal

draft tube and the insert merely adds an additional loss

with the resultant decrease in maximum efficiency tor the

7$~ flow area case

Perhaps the most s1gn1ticant set of eurves is shown aa

53

Figure 22 In this graph values of specific speed tor the

75 and 100~ flow area cases for both over gate and one

halt gate openings are plotted against turbine speed At

every speed and both gate openings the value ot specific

speed for th 75~ flow area case is greater than that for

the 100 t1ow area ease

Since the head is a constant for both situations this

may be interpreted in either of two ways trom equation

(11)

(1) For the same turbine apeed restriction of the

draft tube t1ow area resulted in greater turbine power

(2) For the same power amputput the turbine with 75~

draft tube flow area operated at a greater speed than did

the one with 100 flow area

Since the required diameter of a turbine varies

inversely with the speed the second interpretation could

be stated such that a smaller turbine could be used to

develop the same power output

Whether viewed trom the aspect of increased power

greater speed or reduced size the performance of the turshy

bine with reduced draft tube flow area is superior to that

with the nolmal flow are in the draft tube

The curve of specmiddotific speed versus turbine speed for

the so draft tube flow area case at over gate cond1t1ona

was not included in Figure 22 This curve lies below that

for the 100~ flow area c se at all speeds

In elaboration ot the second interpretation of Figure

22 attention is directed to the relative magnitudes ot

increased apee1f1c speed tor the two gate openings Assumbull

ing that the increase in specific speed implies a shift ot

the power curve to the right along the turbine speed scale

the power curve would be shifted more tor tbe halt gate

opening than tor the over gate opening

It thia trend could be extrapolated to the other gate

openings the tendency can be seen tor the line ot beat

speed to rotate toward the line of the operating speed as

illustrated in FigtU-e ) The advantage of this has already

been discussed

This particular turbine has a low specific speed tor a

reaction turbine Aa the rated value of apecitic apeed tor

reaction turbines increases the line ot beat speed departs

even more radically from the line of operating bullpeed It a

test similar to this were conducted on a reaction turbine

ot gleater specific speed it is pJobable t hat the rotation

ot the line of beat apeed would become more p~onounced

The scheme used in th1a teat had two obvious dr wbull

backs The first was the decision to leave all the wicket

gamiddottes installed tor all conditions ot the draft tube

These gates predominated in control of the tlow The

inserts added to the draft tube merely acted as auxiliary

55

contrGla

The aecond drawback was the choice or device to place

in the draft tube The reasons foll selection of this type

of device have been previously mentioned It is to be

anticipated that adaptation ot dratt tube flow control

would result 1n a better device for an actual turbine

installation Such apparatus might take the form of a

pneumatic bladder or a h7drau11oally operated variable

venturi section in the draft tube It is conceivable that

the gate as used in this test might be adapted also

Chapter VII

OONCLtJSIOfS

From the results of this test the following eonolubull

e1ona aa to the effect ot a variable draft tube flow area

on the performance or a r action turbine may be drawn

(1) The effect ot a variable draft tube tlow area 1a

generally favorable upon the operat1Gn ot a reaction turbull

bine because or the tendency tor the line or beat speed to

rotate toward the line ot operation This resulte in

better performance of the turbine at partbullloads

(2) he etf1o1ency eh111 tor the turbine beeomaa JDore

tlat at the top leading to a smaller max1JilWD effic1enc7

but e reater etticieney at other pointe of operation with

the insertion ot an auxiliary control ror the rate ot tlov

in the draft tube

(3) The power output of the turbine will increase at

over speed over gate conditione as well a at part gate

conditions with the proper amount or draft tube eonatr1cbull

tion or flow

(4) It is possible to eliminate at least partially

eddy type shock loss by tho introduction ot flow control

in the draft tube

BIBLIOGRAPBl

1 Addison Herbert A treatise on applied h-draul1cs New York Wiley 1954 724 Pbull

2 Allen o M and I A Winter middot Co111parative testa on experimental draft tubes Tranaact1ons ot the American ociety ot Civil Engineers 87t893bull970 1924

3 Barrows a E Water power engineering 3d ed ew York McGraw-Bill 1943 791 Pbull

Bovet G A Modern trenda in hydraulic turbine design4middot in Europe Tranaactions of the American Society ot Mechanical Engineera 75975bull993 1953bull

s Oreager William P and Joel D Justin Hydroelectrichandbook 2d ed New York Wiley 19$0 1151 Pbull

6 Daily Jamea w Hydraulic machinery Int Hunter Rouses Engineering hydraulics Hew York Wiley 19$0 p 8$8bull99

Daughertybull Robert L Bydraulie turbines ew Yorkbull7middot MoGrav-Hlll 1920 281 Pbull

8 Daugherty Robert L Inveat1gat1on of tne performance ot a reaction turbine ~anaactiona or the American Society ot Civil Engineers 7811270bull1304 1915

9 Davie L M Model and prototype testa Int Trend in hydraulle turbine practice symposium lranaactions ot the American Society ot Civil Engineers 1o63S3middot368 1941

lfJ Doland James J Hydro power engineering Hew Yorkbull Ronald 1954 209 Pbull

11 Gandy Theodore s and Elmer c Schacht Direct curshyrent motor and generator troubles operation and repair New York McGraw-Bill 1911 293 Pbull

12 Gibaon Arnold H Hydraulics and ita applications5th ed London Constable 1952 813 Pbull

58

13 Button s P Component loases in Kaplan turbinebull and The prediction of efficiency from model tests Probull coedings of the Institution or Mechanical Engineers168743-762 1954

14 Knapp R T~ Oavit t1on mechanics and its relation to the d sign or hydraulic equip ent Proceedings or tne Institution ot Mechanical Engineers 166150bull16) 1952

15 Langsdorf Alexander s Principles of direct curHnt mach1nee 5th ed New York r~cGrawbullH1ll 1940 746 Pbull

16 Lsrner Chester w Characteristica of modern hydraubull lie turbines Trans e~ions of the ~~erican Society ot Civil Engineers 66306-386 1910

17 Linsley Ray K Jr and Jobulleph B Franzin1 Eleshyments of hydraulic enginebullring New York McGrawshyBill 19$5 $82 Pbull

18 Mead Daniel w Hydraulic machinery llev York McGraw-Hill 1933 396 Pbull

19 ead Daniel w Water power engineering New York McGrawbullRill 191S 843 Pbull

20 Mockmore Charles A Part gate operation at water turbines Corvallis Oregon State College Department ot Civil Engineering 1933 11 numb leaves (Unpubshylshed typescript)

21 Mockmore Oharles A Flow characteristics in elbow dratt tubes Transactions of the Amez-ican Society ot Civil Engineers 103402middot464bull 1938

22 Moody L F Hydraulic machinery In c v Davis Handbook ot applied hydraulics New York McGrawshyHlll 1942 1082 Pbull

2) Ptau At-nold Hydrbullulie turbine handbook ld ed Milwaukee AllisbullOhalmers ManufactUIing Company 1948 70 Pbull

RheingalUI w J Recent developments in Francis turshybines Mechanical Engineering 74189-196 1952

25 Russell George E Hydraulica 5th ed New York Henry Holt 1942 466 Pbull

26 Safford A and E P- Hamilton American mixed tlow turbine and ita setting Tranampactions or the Amerieal Society of Civil Engineers 851237bull1)56 1922

27 bull Spannhake W1lhe1Dh Problems or modern pump and tur b1ne design Transactions of the American Society of Mechanical Engineers 56e22$-248 1934bull

28 Sutherlandraquo R A Better ethod or representing and middot tudying water turbine performance ~ansaetions ot thmiddote American Society of Mechanical Engineers 68t675bull 686 1946

29 Teats ot five models or draft tubes tor turbines Engineering News-Record Pbull 182-184 Aug 2 1923

30 White w M American hydztaulic turbines Mechanical Engineering S2t390bull39S 1930bull

31 White w M lhe hydraucGne rega1ner1 its developmentand appl1eat1ons 1n hydroelectric plants Meohanlobulll Engineering 43t37Sbull380 1921 middot

32 Winter I A Economic principlebull in designbull Int Trend in hydraulic urbin practice bull a ampoeiumTranaaot1ona ot the American Society ot Civil Engineerslo6332bull3S2 1941

33 Wiel1cenua G F Fluid mechan1ca or turbo-machineryNev York McGraw-Hill 1947 613 Pbull

APPENDICES

c

Appendix A

NOATIOB

A Angle between the absolute velocity vector and the tangent to the rwmer Subscripts 1 and 2 refel to entrance and exit ot the runner blade

B Angle between the relative 1elooity vector and the tangent to the rwmer Subscripta 1 and 2 refer to entrance and ezit or the runner blade

Angle between the tangent to the runner blade tip and the tangent to the runnel- Subscripts 1 and 2 reter to entrance and exit of the rt1rmer bladebull

Blade angle-gate opening conetant defined by equation (1)

e 09erall efficiency

g Gravitational acceleration assumed constant at 322 teet per second per second bull

H Turbine head detined by equation ($)

m Exit loss coeft1e1ent

Turbine speed expressed in revolutions per minute

Turbine speed under a constant head of 81 teet

specitic apeed of the turbine under a constant head ot 81 teet

p Power output in horsepower ot the tvbine

Power output of the turbine Ulder a constant head ot Sl teet

Pl- Pressure head at entrance to the tUlb1new

l1 Peripheral velocity ot the runneP Subacr1pta 1 and 2 refer to entrance and exit ot the JUnllampr blade

62

v Relative velocity reaulting trom the combination ot the absolute water velocity V and the runner periphshyeral velocity u Subscripts 1 and 2 refer to entrance and exit ot the runner blade

v] Relative velocity vector necessary to produce a tanbull gential entry into the runner blades

V Absolute water velocity Subscripts l and 2 refer to entrano and exit ot the runner blade

v2 Velocity head Subscripts 1 and 4 reter to the ~8 entrance to the turbine and the tail~ace wate~

w Unit weight ot water assumed constant at 624 pounda per cubic toot

V Weight rate ot flow in pounds per aeooncl

XX Velocity component ot ahook See Figule 2

Z Elevation head Subscripts 1 and 4 reter to entrance to the turbine and the taibace water surfacebull

Appendix B ORIGINAL DATA-Run

lfwnber

0-4-1 0-4-2 0-4-3 o-4-4 o-4-S o-4-6 0-4-7 0-4-8 0-4-9o-4-lo o-4-11 o-4-12 0-4-13

o-6-1 o-6-2 06-3 o-6-4o-6middotS o-6-6 o-6-7 o-6-8 0-6-9 o--6-lo o-6-11

Speed

rmiddot2middotbullmiddot(1)

336 38$ 451 S$9 620 669 6lt)$ 120 787 860 932

102imiddot109 bull

352 355 443middot 543middot 620 654AJs32

911 1001 1111

~essure Head rt (2)

410 410 416 426 431 43-7 439 44-9 452 467 482 soo $1 bull $

350 351 35middot7 )66 37-9 37-9 392 41 bull 3 43middot3 460 489

Elevation Bead

fjj $7 $7 $7 $7 $7 $7 51 57 5-15858 $8 58 56 56 $6565656 51 575As5a

Velocit Head

flj 07 07 07 06 06 06 06 os 05 os0404 03

09 09 oa o8 o8 os 07 07 06 o~o

Total Head rt ($)

47middot4 4A44 o 489 49-4 soo $02 $11 $14 $29 5imiddot45 2 576

41 bull $ 416 421 430 44middot3 44middot3 456 47-7 496 523551

Plow

lbtjec

326 324middot317 311 306 30029middot28 middotmiddot middot 386 275middot260 240 218

359 36~35 bull 349 345middot 339 330 318 300 273 240

Line Potential

vyqjbull 1060 1220 ~-0o 1920 2150 2000 2$60 2000 1940 18)015io11 o

1000 1100 139bull5 1760 1925 16$0 1620 1610 1540 1330 870

Line Current

amlscs 960 900 830 740 730655 70bull 0 530 660 600 5imiddot54 6 )60

982 930 860 780 ~3-545

79-5 74-5 670 560 370

P

Appendix B ORIGINAL DATA (Continued)

Run Number

Speed

Pbulltmiddotbullmiddot )

leasure Head ft(2

Elevation Head tt(J)

Velocity He-dfmiddotj

Total Bead tt($

Flow

lbstsec( )

Line Potential vo~ta( )

Line Current

amjs (sect

0bulllt)-1 0-9-2

3ll6 398

28o ~~1

$6 56

1o 10

346 347

390 365

1ooo 1190

aao 835

0-9-3 0-9-4 o-9-S

472 565 632

292 305 312

$6 s6 56

10 o9 o9

)$8 J7~o 37~7

381376 37o

1)6614oo 141o

820 ass ass o-9-6 0-9-7 0-9-8 o-9-9 0middot9-10

680 120 762 844 920

)24337346 366 390

56 $6 56 57 $7

09 os o8 oa 07

)89401 410 431454

367~ 357348 34o 322

1400 1J6o l36o 1310 1170

843 820 7957So 67~0

0-9-ll 0-912

1001 1100

41 bull 7 45-3

s 7 6~0

06 os 480 $18

299 268

980 65$

560 36~5

1-4-1 1-4-21-4-l1-4shy1-4-5 1-4-6 l-4-7 1 4-8 1-4-9 1-4-10 1middot4-ll 1-4bull12

354middot452 562 62q 674shy102 752 760- 863 932

1022 1100-

)82389 4014oa 416 41--7 423 428 44-2 45-7 486 49-2

51S757 51 5-7 5middot15zs sa $8 58 59

07 07 06 06 06 06 06 os o bull o 04 o J

446 45-)46middot4 471 ti7-9480 q86 491505 $19 548 55-4

)28 320 311 306 300 295 291 286 269 2582iimiddot21 bull

1080 14Lo 1550 153-5 1470 141-0 1385 1310 1310 1230 1120 855

970855 875 91-0 94~0 975 966 995 860 77-S 610 4fo

0 ~

Appendix B ORIGINAL DATA (Contirmed)-Run Speed Pressure Elevation Velocity Total Flow Line Line

Number Head Head Head had Potential Current rtjjmbull t~ bttec vyfs am~a12) ( ) ti fli 8

1-6-l $6 33$ $6 0bull9 400 364 1100 93 0 1-6-2 41 34laquo2 $6 oa 406 JS7middot iios a5s l-6-3 500 3~0 5bull6 os 356 1 1 o aos 41middot~1-6~4 35bull4 5-6 oa 41middot 352 16~0 82 0 5~1-6-5 5 bull 36_2 Sbull6 08 42bull6 349middot 161 ~ 0 86~0 1-6-6 622 366 $6 oe 43bull0 345middot 158 0 88~$ 16-A 649bull 37bull1 56 os 43-S 342middot 1570 895 1~- 386 57 07 46-0 192 ) 125A44 333middot 1-6-9 3) 404 5middot1 07 468 317 1620 675 1610 911 42-4 5-7 o6 48-7 298 168 0 61 0 1-6-11 999 451 56 os Sl ll 276 ~2-0 530 1-612 1115 485 58 04 54middot7 238 90 )3 0

1middot9-l 355 279 56 10 )45 385 1040 870 1-9-2 399 28J $6 10 )49 38$ 1140 86 5 l-9-3 ~ ao 291 56 ~0 35middot1 J8J_ JJ6o 815 1bull9-4 579 303 56 09 )68 375middot J4JO 830 l-9bullS 40- 313 )6 09 31middot8 370- 1460 82~0 1-9bull6 679 2) 56 09 3 bull8 364middot 1670 710 l-9-7 682 319 56 o9 384 ) 62 1460 79 5 l-9-8 724 33middot5 56 o8 399 3$6 bull 1480 76 -5 1-9-9 762 34middot3 $6 0 bull 8 407 )48 14910 13middotS 1-9-10 833middot )60 5middot7 os 42$ 339 144$ 686 1-9-ll 926 39middot1 5-7 07 455 318 1290 600 1-9-12 1000 41middot3 0-6 476 298 1115 510$ ~ 1middot9-13 1105 452 s o4 $14 2$6 710 )10

~

Appendix Bt ORIGDIAL J (Continued)

Run Speed Pressure Elevation Velocity Total Plow Line Line Number Head ltead Head jlamp$d P()ten~ibulll Current

r~~~m ft ft lbs~seo voltattj rgj twimiddot t 1 t2gt lt3 ou t ( rt

2-9-1 384 289 S 6 10 35 5 1400 1170 810 2-9-2 443middot 29$ $6 ltimiddot9 360 379middot 11(0 87$ 2-9-J 536 30bull 3 sc 09 )68 374middot 1)40 84 bull) 2-9-4 571 306 $6 09 3~1 372 120bull 0 955 2-9-5 623 316 S6 09 J l )6S UJSo 77$ 2bull9-6 669 327 S6 09 )92 )61 1240 905 2-9bull7 712 )39 56 os 40-3 351 12(0 86 bull0 2-9-8 ~5$~ J48 56 oa 412 348 1290 81 bull ) 2-9-9 04 )63 56 oa 42-7 339 12ltJO 76$ 2middotmiddot9-10 8$2 376 5middot1 07 440 33~- ~ o 710 2-9-11 955 394 5-1 o6 457 300 1100 506 2middot9-12 1000 421 $7 06 48middoti 295 1020 $18 2-9bull13 110~ 463 56 05 $2 267 620 3~0

oshy0

Appendix Gt CALCULATED DAgA

Turbine Run Generator Generator Turbine Turbine Efficiency Turbine Turbine Specit1c

Number OutputKWlt21

Loa~Jes KWlol

Outut K bull (H)

Input RP 12)

middot Percentlt13gt

Speed r~Jmiddot(

0ltput HP ~1

Speed r-m

( 6) middot

o-4-1 0middot4-2 0-4-3 0-4-4 0-4-5 0-4-6 O-qmiddot7o-4-8o-4-9 0-4bull10 0-4-11 o-4-12

1018 1o9a 1220 1)62J40214oa1J4oo 1357 1320 1164 997 718

046 o59 071 092 096 1071oo 134 104 100 109 107

14261sso 17)01948 2008 20322011 1999 19 09 1708 14-84 11o6

281279 27-7 276 215 273271 268 268 26h 258 24-5

soa 555 62$ 705 7)1145 742 74-6714645 51s 45-1

440 sos 585 720 195 sso sao 9$$ 985

1065 1135middot 1230

318 357 319 416 422 419412 39middot9 378 324 260 191

102 12bull4 148 191 21bull 3 22o 233 249 24924middot9 238 221

0-4middot13 418 104 699 228 306 1300 117 18)

o-6-1 982 045 1376 271 $08 496 376 124 o-6-2 o-6-3 G-6-4o-6-5 0-6-6

1023 1200 13 73 J415 139h

051 0middot66 oaa ()bull 96 088

14-39 1696 1958 2026 1986

276 27middot4 273 278 274

$20 61 8 717 7)0726

q95615745 8)5685

390 ll5middot3 sos soo 490

127 170 218 243 2$$

o-6-7 o-6-8 o-6-9o-6-lo

1288 1199 1032 7-45

o9o 094 09$ 096

1846 1733 1511 1128

274 276 271 260

67S 629559 43middot4

980 1085 1165 1245shy

436 )83316 21bull 7

266 276 270 239

0-6-11 322 1oo 566 2141 2JS 1350 101 177 0 --4

Appendix C CALCULATED DAlA ( Continued)-Run

Number Generator Generator

Out2ut Losaes xw LW- 12gt (lO)

Turbine Out2ut

ltPlJ

Turbine Inat lfP Jig)

Etpound1e1ency

PireentDl

Turbine Sed x-~m( 1

Turbine OutEut RPJl)

Turbine Specific

SeeedrIbullntbull

( 6)

o-9middot1 0-9-2 0-9-3 o-lt)-4 09-$ 0bull9-6 0-9-7 0-9-8 0-9-9 0-9-10 o-9-11 0-9-12

aao 994

111$ 1197 1206 1180 11)21081 982 784 5-49 2)9

0middot45oss o6$ 070 07$ 0-77 (l77 or~ o s06o 8 096

123~ 1402 1$80 1698 17bulllS 168$ 16bull18 ~middot5430 1151 a~J4 9

24middotgt24middot3248 25~25 260 260 259 267 266 26middot1 2S2

sos 577 63-7 671 676 650 621 60036J4

327 178

$) 610AlO 3$

92S 980

102$ 1070 1157middot 1230 1300 137Smiddot

44middot4 soo 523 ssomiddot 540so6 46-5 432 368 274 18~8

J46 176 21-1 255 2802s_A 28 289 288 265 231 168

1-4-1 1-4middot2 1-4-3 1-4-4 1-4-5 1-4-6 1-4-7 1-J-8 1-4~9 1-4-10 1-4-11 1-4-12

10bull48 1231 13-S6 1397 1)821375 1))8 1303 1127 953 683) 51

048 067 o7A07 0 bull79 oa1 oss o bullao osa 0lt)0 096 099

J468 1740 1921 1978 1958 19$1 1911 lSSi162 1)98 1045

603

266 264 262 262 261 2512$7 2$6 24middot7 24-3 233 217

551 660 13middot3155 75-6 7~-97 middot4 72$ 67 51middotJ 44middot9 21middot1

475 605 A4220

875middot 910 970_

1000 1090bull 1166 1243 1330

5816

44middot444middot5 430 427 412 392 329 273 188 l0-7

117 101 204 22$ 2)7245 2562sa 257251 222 179

a-C))

Appendix Ct CALCULATED -DATA ( Ocntinued)

1-6middot1 1023 o$2 14-41 26S 505 41~6 26~

54middot5 13middot3l-6-2 1201 067 1boo 625 47-9 17shy~middot41-6bull3 1296 oA9 1 middot43 26 9 700 so5 20bull 4 l-6-4 l3j5 o 0 19~09 268 71bull3 A5o 514 222 1-6-5 1) 5 o81 19(gt4 271 725 51-5 238 l-66 1398 081 198) 27-0 736 8 S13 252~-middot l-6j 1405 083 199i 211 733 885 $middot06 2$9 l-6 13middot9~ 103 2amp 0 279 71 8 985~ 467 ~-69 1228 1 bull 02 17-SS 270 661 109$ 407 ~3~ l-6bull10 1025 100 lSll 26i 573 1175middot 27~S32middot~l-ampu 153 1-00 llft3 26 444 1270 22 24bull8 1bull6-12 294 100 52a 231 22 3 1360 95 172

1-9bull1 904 048 1275 2J4Z $28 S4$ 459 1$2 1-92 98$ oss 13-92 24middot4 57-0 6JO 49bull1 176 1-9middot3 1110 066 1$76 24middot9 63middot4 I2o 536 21-7 l--9-4 1187 072 1685 251 66$ 5 $$ bull 0 261 1middot9-5 llltJ7 1710 25middot4 67-3 93$ 536 28~20-671middot9-6 1186 o 8 1708 25-7 67) 980 $15 2691-9- 1161 oBo 1660 2$middot3 6$6 990 508 29-1 l~- ll-32 oB) 16sect0 2$8 632 1030 471 291 1-9bull9 109$ oa5 2$7 614 1075 29S~middot 0 4imiddot41-9-10 9~91 oas 262 S$1 1150~ 3 o 292 1-9-11 o9o u57 12JiO 21gt 26-77middot74

-45 26sect ~middot91-912 $69 091 sas 25 middot3 1)0$ 196 2J-8 1-9-1) 220 098 426 2)9 178 1390middot 84 16 6

0 0

Appendx C CALCULATED DATA (Continued)

Turbine Run Generator Generator lurbine Turbine Eft1e1eney Turbine lurbine Spee1f1c

Number Output Losses Outit Input Speed Output SPed middot k_-V KW R _ H_bull_P Percent r Thm HP rpm_ (9) tlo) 11) middot (12 _) (lJI ( ) (1$ (14)

2-9-1 9--46 055 1)62 258 528 580 164 2-9-2 1024 056 248 58 4 665 4 9 191iimiddot48 4~middot0 2-9-3 1132 067 05 2$0 641 795 52q 237 2-9-4 1148 065 1027 2$1 -~8 845 525 252 2-9-5 11 77 oso 16-83 253 6 910~ 522 270 2-9 6 1122 071 1600 251 622 960 47-5 2722-9-A 1092 015 1562 257 608 1010 445 2z12bull9- 1052 079 1514 261 580 1060 41middot7 2 2 2middot9-9 986 o82 ]429 26) 542 1105 372 277 2-9-10 915 086 1340 268 500 1160 334 27-6 2-9-11 638 087 972 254 )81 1270~ 229 250 2-9-12 )28 090 828 259 )19 1295 179 226 2-9-13 192 094 383 2$ 6 150 1370 7 3 152

-3 0

Page 21: The Effect of A Variable Draft Tube Flow Area on the

Chapter III

PROPOSAL OP ALlERMAlE MFTBO 0 CO TROL-A lz ~ Location 2 Control

Thua tar only practice and theoretical aspects appemiddotrbull

taining to present day turbinea have been d1acuaaed It

haa been presented that control over the ~bine ia ezerbull

oiaed b y manipulation of the wicket gatea located 11101led1bull

ately preceding the runner These gate - upon rotation

modify both the magn1tu4e and the direction ot the entering

velocit7 Moreover it has be n shown that a simultaneous

change in these two variables leads to inefficient operabull

tion by the introduction of shock loss he farther the

point of operation a from the rated conditione the more

aerioua ia the ahock loss encountered

Any attempt to better turbine pertorance at other

than rated conditione and tbne flatten the top ot the

etticieney hill8 must concentrate upon the lessening ot

the ahock loaa It 1a a aumed that 1 provement in the

scroll case gates and runners would lequ1re sueh pertecbull

tion 1n machine work and metal$ as to be prohibitively

expensive

It ie surmised that any move to elblinate eYen parbull

tially the shock loss would require separate control ovel

l$

the flow and gate exit angle Since it is improbable that

d1~ect1on could be controlled at any location other than

where the gatea are situated in current turbines it will

be assumed that guide vanes will be necessary regardlesa or the method used to control the rate of flow

The primary purpose ot th se guide vanes 1s that or control over the direction ot the incoming water They

should be free to rotate in much the same manner as ordibull

nary wicket gates in order to exercise control over th

turbine speed

If the rate ot tlov is to be controlled elsewhere it

must be modified either in the penstock or the draft tube

Devices that could be used are standard valves gates

variable orifices variable venturi sections and associated

flow regulating schemes

Alauming it were decided to locate such a device upbull

stream of the turbine it would be necessary to allow disbull

tance tor the flow picture to become reestablished prior to

entry to the turbine A contused flow making transit of

the turbine passages would only contribute additional loesbull

ea Such a distance allowance would be perbapa 20 to So

diameters (2$ Pbull 119-123) In large penstocka th1a would

repreaent a considerable distance Which from the viewbull

points ot convenience and control would be undesirable

Attempts to ascertain the effect or additional tlov

16

reduc ion at the wicket gatctsmiddot wae ade 1n the lfadraulioe middot

Laboratory of Oregon St middot te College in 1933 (20) Three

d1tterent thode ot reducins the tlow were t~ied

(l) Locking in the cloeed position pairs or wicket

gatea located opposite to eaeh o~er on the -periphery ot

the wheel

(2) Locking adjacent gates in an open position by

inserting blocks of wood between them and

()) Suocess1vely looking adjacent gates in the closed

position

The results indicated a arked reduction in both power

and efficiency when compared to the curves tor normal gate

operation However it was demonstrated that it was poae1bull

ble to ahitt the power and tfieiency curve ill relation to

turbine apeed lbis important feature will be diacussed

later

ihe main conclusion of the investigation was that conbull

trol by the conyent1onal wick t gates was auper1or to other

methode egtt control exercised at the gates the aelvebullbull

It would app$ar that the bebullt location tor flow conshy

trol would be in the draft tube since none of the objecbull

tiona prev1ously mentioned wou~d eziat there

As bas been stated previously the sole object or the

17

18

turbine is to produce power as etfic1ently as possible

The equation tor the power output of a turbine () Pbull 227)

PaWHe HP (4)55o bull bull Assuming the head 1a constant and a g te located in

the draft tube decreases bhe rate ot flow the power eu

only be increased if the etticiency increases

The ettective head Gn the turbine 1s conventionally

d r1ned as the difference between the auma ot the elevashy

tion head pressure head and velocity head at the entrance

to the turbine casing and the tailrace ($ Pbull 872)

lt ie recognized that the theoretical treatment ot

shock loss as given is highly approximate and serves only

to dictate certain trenda For example the area at xit

rom the wicket g tea CfUl be measuPed with some exactness

but there exists no guarantee that the wateP particles will

complet-ely fill the apace oz- will exit at the establiahed

g te angle The same can be said of the exit trom the

runner blades AssUIlptiona were implied which would indishy

cate that all water particles passing a given croea section

ampH traveling at the same velocity in the same direction

the e alone are autt1c1ent to show 11m1tationa in a theoretbull

1eal approach to the problem

Assume a turbine with ordinary wicket gates tor oonbull

trol compared gainst the same turbine with a gate in the

18

draft tttbe tor supplampment1ng control or the rate ot rlow

Let it also be assumed that the two turbines are opershy

ating at the same point It 1s desirable to predict relabull

tive performance of the two turbines 1 this point of

operation is such that edd7 s hook loss ot reasonable proshy

portions is present in the fir t turbine

~ tull erteot of the shock loss will be exper1 need

by- the fir t turbine

lhe second turbine will derive certain advantages 11

the gate in the draft tube is adjusted to reduce the tlov

1n the proper amount Since they vary a the square ot

the veloo1t7bull the lossabull in the aeroll case wiomiddotket gate

and runner passages will decx-ease aetet-r1ng to Figure 2 1

it can be seen that a decreased velocity v1 w-ill reduce the

eddy shock losa

The ent loss in the dJtaft tube of the second turbine

will be the sum ot the tr1ct1onal loss and the velocity

head at ex1t The velocity head dissipated will be greater

due to the closing action or the gate but the reduoed

t~ictional loss which ia a tunction ot the rate of tlow1

will partially balance this

It 1a entirely possible that the net reduction in

losses in the second turbine will lead to a greater ettibull

oiency and more power output than 4eYeloped by the first

turbine

19

In Figure 3 the plot ot power output against turbine

speed for Curv A~ represents the typical family of curvea

tor a reaction turbine Th b st sp ed is the locus ot

points connecting maximum eft1oiency at each gate opening

The operating speed is the coZUJtant turbine apeed which

passes through the point ot maximum efC1ciencr of the turbull

bine The plot of turbine efficiency against power output

for Curve A is also ahown

It the turbine with flow regulation in the dratt tube

oan demonstrate superior power and efficiency at part loads

the effect would be the same as a shifting or the power

curves toward the condition shown fop Curve B 11 Thisbull

illustrates th ultimate case of the uperpoait1on of best

and operating speeds It will be noted that the pet-form~

of the turbine ot Ourve Bu 1a better than that of CUrve

A at part loads because of ita ability to sustain a relabull

tively high etticienoy ovel a Wider range of power output

o Reguireaegts tort Test Velitication

It is desired to deterra1ne the effect on the turbine

performance b) the addition of a gate in the dratt tube

Th step in the teit will bet

(1 To determine the power output and efficiency ot

the turbine tor wicket gate settings above and below rated

conditione for a wide range ot speed

20

CURVEAbull

TURBINE SPSBD TURBID SPEKD

POIBR OOTPOl

Figure 3 - Turbine Performance Curves

21

22

(2 peat (l) with the gate installed in the drat

tube

(3) middot Converting middot all data to a constant head compare the

powere and effioiencies at the same wicket gate setting and

turbin speed tor the two cbullses

If the ddition or the gate indicates an improvement

in power output and efficiency and the powe~ curve shifts

to the right along the turbine apeed scale the advantage

ot draft tube con~ol of the flow will hav been demonshy

strated

Chapter IV

A E9J11pment

ih turbine used in this test is lJ 5 1nch Pelton

reaction turbine with a rated output ot 30 horsepower under

a head of 56 feet at a speed ot 720 reYolutiona per minute

Views of this turbine are hovn in Figures S and 6 The

turbine is installed on a concrete pad located over an open

channel in the Hydraulics Laboratory at Oregon State Colshy

lege The date of manufacture of this turbine was 1915

The water was delivered to the turbine from a sump

reservoir by two pumps operating 1n parallel Each pump 1a

an 8 inch Pelton double suction centrifugal pump witb a

rating of l$00 gallons per minute at a head ot 75 teet with

a speed ot 1175 revolutions per minute Tbe inlet tlange

ot tne turbine is $pprox1mately 18 feet above the center

line of the pump

A direct current generator was coupled to the turbine

to receive tne power d veloped as shown in Figures 4 and 7 The generator is a Spr gue Electrodynamometer rated at SS horsepower with a speed range of 7$0 to l$00 revolut1one

per minute The classification is type LO 26A 2)0 volta

Figure 5 - View of Test Turbine

Figure 6 ~ View of Test Turbine

and 149 amperes lbe generator ti ld was aepar tely

excited using direct current from a motor g n r tor ampt

(l$ p 4~8)

The power output of the generator waa dissipated in

the water rheostat (3 p 488-489) shown in Figures 9 and

10 The galvanized tank contain d water ot variable d pth

on an electrode ot cast iron m aauring 1bull x 1 x 1

In the initial installation of the turbine it was

intended that the power output should be measured with a

Prony brak bull For th purpoa68 or this teat it was decided

that the brake was too instable and the generator was

substituted The platform for raising the generator the

nee asary two teet for alignment was built out of available

material In this case heavy laminated wood blocks reiashy

torced with other timbers were used and bolted through the

concrete deck (11 Pbull 36-$7)

Due to the light concrete deck the lack ot mas in

the platform and the slight misalignment in the flexible

coupling ao e vibration waa encountered It seemed to

ncr aae linearly to a maximum at the speed of bout 750

revolutions per minute Above this speed no vibPation was

noticeable The vibration waa not se~ere and does not

appear to have materially affected the test results

26

B Intrumentat1on ~ eaeur1ng Devices

The pressure head at inlet to the turbine vaa meaave4

bymeane ot two )6 inch waterbullmeroury manometerbull connected

in series as shown in Figure 8

The terminal voltage ot the generator vas meaeured by

a laboratory voltDleter with a range to )00 yolta and callbull

brated to within 15 Yolta

The armature current bull and hence the line current was

measured by a laboratory ammeter with a range to 150 amperea

and callbrated to w1 thin o 7S amperes

Tae rate ot tlow was established by weight and time

meaeurementa The weighing ank has a capacity ot 121 000

poundsJ the weight belng indicated by Toledo direct reading

scales Timing was done with a hand atop watch with clivibull

aion ot 02 second

he ~ater level in the tailrace was dete~1ned by a

hook gauge lhie was read to the nearest 001 toot

The turbine and generator speeds were eaaured by a

hand tachometer The technique of almost cont1nuoua readbull

ings of the speed gave an error ot no more than 5 revolubull

tiona per minute

c Operational Procedure

Atter the water level in the aump was checked to

insure an adequate auppl7 the puapa were primed and

27

Figure 7 - Test Generator and Plattorm

Figure middot8- Instrument Board and Field Rheostat

28

started After venting they were valved for operation 1n

parallel

The motor generator set was started to supply the

field current and the circuit breaker was closed Water

wa added to the water rheostat to the level shown in

Figure 10 ~ field current wae minimized by cutting in

all the f ield resistance in the field rheostat of Figure 8

The l2 inch gate valve shown in Figures 5 and 6 waa

slowly opened and the turbine and generator brought up to

speed The 12 inch gat valve and turbine were vented and

the pumps were checked to insure neither had lost ita prime

lhe water rheostat offers very steady load 1f the

water level is essentially constant and the water temperabull

ture 1a fixed () p 488~89) In order to maintain this

constant temperature it was decided not to circulate the

water in the rheostat but rather to allow the water to

boil thua achieving the desired result A standing wave

was set up on the face ot the electrode by the boiling

action but a atable load was eatablished except at very

low water leYels where th11 agitation led to fluctuationa

in the line current

After putting the turbine and generator on the line

maximum power was dissipated in the rheostat by redueing

the turbine speed to between oSO and Soo revolutions per

minute Salt vas added to the rheoetat wat r to increasemiddot

29

Figure 9 - View of Water Rheostat

Figure 10 - View of Water Rheostat

Separate Field ExcitationFrom Motor-Generator set Compound Water-Mercury

---shy

re Manometer

I Q)

~ 0

~

Book Gauge

Open Channel

I

Slap Reservoir

Figure 11 - Wat~r Flow Diagram and Electrical Layout

31

waiting pe~iod ot perhaps an h~ followed

while the boiling point or the water wbulls reacbe4 During

this ti+ne the manometer was vented end eheoked electrical

measur1ng 1nstlUments were connected end the hook gauge was

adjusted tor elevation

It required about two- houtte tor the generator to reach

its normal operating tempe-ratu~e_ After the water in the

rheostat and generator had reached their operating temperabull

turea it was possible to begin the taking of data

The only vaPiable which was controlled wee the turbineshy

generator speed However the upper l1ut1t of safe line

current was slightly over 100 ampJilPampPes and the eireuit

breaker would open when the current reached lOS ~ere bull

Control was exercised by means ot regulating the water

level and salt 1n the water rheo tat and the res1stsnoe of

the tield rheost t~

The etfeet ot each type ot regulation on the three

variables is shown below

Volta Aaperebull Speed

Inc Dec Inc Dee~ Inc Dec

Wa~e1 Level Inc Dec~ X

X X X X

X

Salt Concentration

Inc Dec X

X X X X

X

field Resistance

Inc Dec

X X

X X

X X

32

Jlot all methods gave the ame amount ot change in a

given variable and a period of experiment and trial led to

the following scheme starting the rune with the lowest

turbine speed the water level was high with a high amount

ot salt and the field resistance was cut completely out

Aa it became necessary to increase the speed tor each

aucceasive run either cutting in t he field resistance

decreasing the salt concentration or lowering the Vater

level would produce the desired result However decreasbull

1ng the salt concentration had to be done Without a net

gain in water which led to a tluahing procedure that was

not particularly good because cold water was introduced

which required time to heat to the boiling point Cutting

1n additional field resistance was a good method but th1a

increased the amperage possibly to the point of opening

the circuit breaker Lowering the water level was aatiashy

factol1 until the level got too low causing the current

fluctuation previously mentioned Actually it turned out

that a combination of lowering the water level and cutting

field resistance in would carry the speed from ita minimum

to 1ts maximum value it the proper choice were made each

time the speed waa to be changed At the conclusion of

each aet of runs at a high speed the water level would be

low and the field resistance high

33

TURBINE

PAD AND DECK

TAILRACE

WATER SURFACamp

CONCRETE

DRAFT TU1B INSERTS

7 5( DRAFr TUBE

FLltJI ARIA

5~ DRAFT TUBE

FLOI ARSA

Figure 12 - Sketch of Draft Tube and Test Inserts

34

Figure 13 - View of Draft Tube Insert

Figure 14 - View of Draft Tube Insert

D c __ ~s_middot hedu_le of

A number was assigned to each run The fi~st number

applies to the draft tube tlow areas

1 bull 100~ flow area or 0~ oonatriction

2 - 7S tlow area or 2$ conatr1ct1on

3 SoC flow area or so~ constriction

The second number refers to the wicket gate openings

9 over gate opening

6 bull intermediate gate opening

4 bull one h lt gate opening

The third number 14entif1ea the location of the particular

1Wl in a set ot rona made at a given dratt tube tlow area

and wicket gate opening

fnua run number 1bull4bull10 would identity this as the

tenth run ot a set made at halt gate with 75 ot the draft

tube t1ow area

Rune w re made tor a g1yen dratt tube condition

Firat tor tull 41-aft tube flow area seta ot rune were

made for the overgate halt gate and intermediate gate

conditione An insert was placed in t he draft tube and

rune based on the same gate conditions were made tor the

7S~ draft tube flow area case The insert was then changed

to allow only $~ draft tube flow area

The inserts are sketched 1n Figure 12 and photographed

ln Flgurea 13 and 14 They oonaisted of circula~ segments

36

or l2 ineh plywood mount 4 on wooden legs 10 inches high

The 1nse7te were placed in position and secured by th use

ot a-clamps on the legs and the outside ot the bottom of

the draft tube The obvious disadvantage to this method

waa the neoeasity tor draining the water from the tailrace

tor a change ot 1naert The advantage vas of course the

simplicity ot design and construction

Chapter V

DATA-A Original Data

The normal data-taking crew consisted or two men

Assuming adjustments having been made to secure a certain

turbine speed (aee section on Operational Procedure) one

man would take semi-continuous speed readings with the hand

tachometer until a state or rotational equilibrium was

reached This could be only a period or two minutes up to

ten or tifteen minutes As soon as steady speed was

assured the data taking would begin The second man went

to the weighing tank Where a minimum ot three weighingamp

were made The requirement was to get three consecutive

readings such that the ditterence between tbe smallest and

largest time did not exceed 04 seconds The time to

collect a given weight ot water was then assumed to be the

arithmetic average of the three times He then went to the

hook gauge determined the hook elevation and then

recorded the data on the data sheets The first man meanshy

while had taken readings of the line voltage line current

and manometers and checked the turbine speed by multiple

readings During the length of the run all values were

38

checked to determine mean values for recording

The minimum length of one run was about five minutes

If one or more measure ants tended to drift during the run

all values wer discarded and a new run began as soon aa

qu111br1um was stabl1shedo

B -0-al_e_u_l_a_t--d Data

The h d on the tu~bine 1 defined by

($)

The maxtmwm velocity V4 was equal to about o8 tampet per

secon4 which makes it a negligible quantity when converted

into velocity head

An engineerbulla level was used to deterine the d1ffePshy

ence 1n elevation between the compound water-mercury manoshy

meter and the hook gauge Using this value the equation

for turbine bead becomes

where z4 is the hook gauge reading

The rate of flow 1 cent

w weight or water collected average time to collect

The inlet velocity v1 vas calculated by dividing the

weight rate or flow by the specific weight of water and the

)9

area ot ~e inlet pipe This was equivalent to dividing

the weight rate of flow by 490 Then the power input to the turbine is equal to

WHpin rri

10 (6)

Also

(P ~ut) Turbine

(P out) + Generator

(P lost) Generator

The power output of the generator is simplJ the

produot ot the terminal voltage and the armature (line)

curPent The power lost in the generator can be subdivided

into copper losses and stray power losses lo evaluate

these cunes based on losses of an identical generator

11leampsured by the Department ot Mechanical Engineering were

used The loss curves are reppoduced in part in Figures

15 and 16

Determination ot generator losses proceeds as tollowau

(1) From Figure 15 detem1ne the vo1tage drop in the

armature circuit using the temperatures of 1220 F and the

meaaured current

(2) The induced voltage is t~e sum of the terminal

voltage and the voltage drop 1n the armature circuit

() Entering the induced voltage and the turbine speed

into Figure 16 the stray power loss can be determined

(4) The copper lose can be evaluated from Figure 1$

using the measured current and the temperatlll-e of 1220 P

40

25 ~------~--------~--------~------~

U) -U) - 20

f-4 ~

-~ -gt 0

0

VOLTAGE DROP

~ - i -

- bullbullbull bull - -middot-middot -+ ~- + -t--+ ~ - ~ middotbull ~-~ middott- -+----- _ -4 middotmiddot- --~-+-t---r~~ ~--+t-t- - ---t-c-++~-ulf--

0 50 75 100

Figure 15 - Curves of Generator Voltage Drop and Copper Loss

41

1200

1000

800

600

800

0

0

~-

middot--~ 1shy --1 + bull l

100

I -

150 200

IIDOOED VOLTAGB (VOLTS)

Figure 16 - Curves of Generator Stray Power Loss

_ j

-bullshy -L---- shy middot -shy

250

- r

42

(5) The generator los os equal the sum of the eopp r

loss and stray power loss

~e efficiency or the turbine is taken as

etticiency u e =P out (8)Pin

~ample pound Determ1n1gg turbine Power Output

The following data are taken trom that ot Run 1-9-1

Line voltage 1040 volts Line current 870 amperesSpeed 355 revolutions per minute

The induced voltage 1a determined as follows

Line voltage 1040

Voltage drop 90 using Figure 15 with line current of 870 amperes and temperature ot 122 degrees)

Induced Toltage 1130 volta

The power output of the turbine is determined as follows

Generator output 90$0 (line voltage z line current)

Oopper loss 7 (using Figure 15 with line current of 870 amperes and temperatUe or 122 degrees)

Stray power lose 470 (using Figure 16 with speed ot 355 revolutions per miDUte and induced voltage or 1130 volts)

Turbine power output 9527 vatta

or turbine power output 1s 12z2 horsepower

43

The conversion of the calculated data to a constant

head is based on the conventional assumption of constant

efficiency regardless of turbine head For a constant head

ot 81 teet a purely arbitrary figure the tollowing relashy

tionships are ass1lJiled to be true

I ____L (9) (i)l72

(10)

For these two values the specific a peed may be combull

putedt

N t Jt VPt (11)8 243

Chapter VI

~RESULTS

A -Pr_e_ae_n_t_a_t_t_o~n g Reaultbull

Graphical presentation ot the results ot this te1t

are given as follows

Figure 17 -Turbine characteristics with 100~ dratt

tuba 1low area

Figure 18 - Turbine characteristics with 7S dratt

tube tlow area

Figure 19 bull Comparison ot power and etticiency at

over gate conditions between 100 and

75~ draft tube flow area

Figure 20 bull COZQparison of power and ettic1ency at

halt gate conditions between 100~ and

7S~ draft tube flow area

Figure 21 bull Comparison of power and etticiency at

over gate condition between 100~ and

So dratt tube tlow area

Figure 22 - Comparison in variation ot apec1t1c

speed between 100 and 75~ dratt tube

tlow area

50

45

20

-bull - 1--shy40

bull J-~ 30

~ ex

~ 20

~~ ~ -)q

I

~ - _

- -

10~ OF DRAFT TUBE FL(Jif AREA

CONSTANT HEAD OF 8l FEST10

POIER OUTPUT EFFICIENCY SPECIFIC SPEED

0 ~--------------_--------~------~------~ 400 600 800 1000 1200 1400

TURBINE SPEED (RPM)

Figure 17 - Turbine Char~cteristics with 100 Draft Tube Flow Area

50

46

-bulllle

~ 7 ~ OF DRAFt TUBE FLOW AREA

0 -~~-rl C05STAMT BEAD OF 81 mET 1J~

POIER OOTPUT ---+- ---o ~_H EFFICIDCY ~ I shy

bull ql SPECIFIC SPEKD - ~ -

bull ~ J 10 L rmiddotr- r- -

bullz- I

~~ 30 ~~--~----~~-

20 ~ ~ middot-shy

26

~~ 25

~0 ~r-----i (

Tbull -bullshy

400 600 800 1000 1200 1400

TURBINE SPEED (R PK )

Figure 18 -Turbine Characteristics with 75 Draft Tube Flow Area

47

EFFICIENCY 60

1-----shy

-~ 50~--~--~~-~middot middot middot middot r~-~----~~~~---4~-r~-~~gtt

II

POWER~ J ~ bull bull

u I

sH

40~------+-------+---- -~~--~~-~~~~

~----~rl 1 bull

I

I

0~--------------~------_------~--------

~ -OVER GATE CONDITION

COIJSTANT HEAD OF 81 FEET

0 o 10~ DRAFt TUBE

_-- _ 7~ DRAFT TUBamp FLON AREA II

10_~-----+--------r-------r----~~

400 600 800 1000 1200 1400

TURBINE SPEED (RPM)

Figure 19 middot - Comparison between 75 and 100 Draft Tube Flow Areas of Power and Efficiency at Over Gate Conshydition

48

t

bull --4 r ~- ~ middot~

70 1-----------+-~~~~~+middot ~ ~~ middot middot -~~--~~--------~~----~-+1

-~-

Atbull bull

lla-

60

amp0

40

20

10

oampOO

t _ - - ~-+- - -~-

l2 GATB COJIDITIOJJ

COJISTABT HJW) OF 81 JBET

o 0 lOQ( DRAFl TUB8 FLOI AREA

e-- - e 75 DRAFT TUBE FLOW AREA

800 1000

- r-

~

TURBIbull SPBIID (RPII)

Figure 20 - Comparison between 75 and 100 Draft Tube Flow Areas of Power and Efficiency at Half Gate Conshydition

49

60

50

-40

bull 30

IIQbull

20

10

0

400

- t - ~

EFFICIENCY

_J bull - bull bull

~ r r middot t -+ shy L -t -

OVER GAD COliDITIOI

CONSTABT BEAD OF 8l FBB

o o 10~ DRAFt TUBE FLOI ADA middot--- 5~ DRAF TUBE FLQPi AREA

600 800 1000 1200

Figure 21 -Comparison between 50~ and 100~ Draft Tube Flow Areas of Power and Efficiency at Ove~ Gate Conshydition

50

25

20

15

10

0

Figure 22

~- T -4 -t- -l --~-

t-~ I

middot --~- t ~---- _ __ _ + --

----~- --r-- --

~-=J-~-=-~ -==~ _ ~- -- ---f---1 - shy

CONSTANT HEAD OF 81 FEBT

o--o 1~ DRAFT TUBE FLltll AREA

75C DRMT TUBK FLCIJ AREAmiddot--middot-middot 600 800 1000

TURBINE SPEED (RPK)

Comparison of Specific Speeds for 75 and 100 Draft Tube Flow Areas

51

B Discussion 2 Result

Consideration of Figures 17 and 18 indicates the

overall eftioi ncy pattern or hill is significantly or

rounded for the 7$~ flow area than for the 100~ flow area

bia implies a greateP efficiency is possible at speeds

leas than or greater than design speed with an insert in

the draft tube However the muilDum efficiency is lemiddotas

Direct comparison at over gate conditions is made in

Figure 19 ~e same general trend is noted tor both the

etticiency and power curves for the 7$~ flow area case

The eurves show higher values at overspeed than do the

correaponding cWvea for the 100 flow area case It ia

not clear whether the curves have been shifted by the dratt

tube constriction or whether the curves simply bulge past

the normal curves at both overspeed and underspeed condishy

tions The power curves apparently peak near the aeme

point bullalthough maximum power is still obtained with the

normal draft tube area

For the comparison at halt gate operation shown in

Figure 20 a general improvement has apparently been made

by restriction of the draft tube flow area At every speed

the etticienoy and the power is greater for the restricted

tlow case The two ett1o1ency curves and two power curvea

are practically parallel throughout the speed range ot

teat

As the flou aroa i e decreased still farther a s1gn1

ticant change appears Reterr1ng to Figllle 211 tor the $0

flow area curves it a obvious that exit losses have

become excessive at the overgate condition because the

efficiency and power are everywhere leas than tor the case

of normal draf t tube area

Earlier it was pointed out t hat 1t the r esult s 1nd1bull

eated an increase in both power and ef tieiency- t hen it

could be assumed tha t the additional los s i ntroduced with

the draft tube insert is less than the diminished losses

due to leas shock losa and water passage losses For the

places where both the efficiency and power have been

increased we can assume that the insert has improved turshy

bine performance

For the places where the power haa been decreased

nothing can be said as to the elimination of ampbock loss

because the new lose present with the drat tube insert has

overshadowed any gains in eftecti Ve head upatJ-eam of the

insert

Near the peak of the efficiency hill howeve~ it may

be pointed out t hat shock loaa ie a minimum with a normal

draft tube and the insert merely adds an additional loss

with the resultant decrease in maximum efficiency tor the

7$~ flow area case

Perhaps the most s1gn1ticant set of eurves is shown aa

53

Figure 22 In this graph values of specific speed tor the

75 and 100~ flow area cases for both over gate and one

halt gate openings are plotted against turbine speed At

every speed and both gate openings the value ot specific

speed for th 75~ flow area case is greater than that for

the 100 t1ow area ease

Since the head is a constant for both situations this

may be interpreted in either of two ways trom equation

(11)

(1) For the same turbine apeed restriction of the

draft tube t1ow area resulted in greater turbine power

(2) For the same power amputput the turbine with 75~

draft tube flow area operated at a greater speed than did

the one with 100 flow area

Since the required diameter of a turbine varies

inversely with the speed the second interpretation could

be stated such that a smaller turbine could be used to

develop the same power output

Whether viewed trom the aspect of increased power

greater speed or reduced size the performance of the turshy

bine with reduced draft tube flow area is superior to that

with the nolmal flow are in the draft tube

The curve of specmiddotific speed versus turbine speed for

the so draft tube flow area case at over gate cond1t1ona

was not included in Figure 22 This curve lies below that

for the 100~ flow area c se at all speeds

In elaboration ot the second interpretation of Figure

22 attention is directed to the relative magnitudes ot

increased apee1f1c speed tor the two gate openings Assumbull

ing that the increase in specific speed implies a shift ot

the power curve to the right along the turbine speed scale

the power curve would be shifted more tor tbe halt gate

opening than tor the over gate opening

It thia trend could be extrapolated to the other gate

openings the tendency can be seen tor the line ot beat

speed to rotate toward the line of the operating speed as

illustrated in FigtU-e ) The advantage of this has already

been discussed

This particular turbine has a low specific speed tor a

reaction turbine Aa the rated value of apecitic apeed tor

reaction turbines increases the line ot beat speed departs

even more radically from the line of operating bullpeed It a

test similar to this were conducted on a reaction turbine

ot gleater specific speed it is pJobable t hat the rotation

ot the line of beat apeed would become more p~onounced

The scheme used in th1a teat had two obvious dr wbull

backs The first was the decision to leave all the wicket

gamiddottes installed tor all conditions ot the draft tube

These gates predominated in control of the tlow The

inserts added to the draft tube merely acted as auxiliary

55

contrGla

The aecond drawback was the choice or device to place

in the draft tube The reasons foll selection of this type

of device have been previously mentioned It is to be

anticipated that adaptation ot dratt tube flow control

would result 1n a better device for an actual turbine

installation Such apparatus might take the form of a

pneumatic bladder or a h7drau11oally operated variable

venturi section in the draft tube It is conceivable that

the gate as used in this test might be adapted also

Chapter VII

OONCLtJSIOfS

From the results of this test the following eonolubull

e1ona aa to the effect ot a variable draft tube flow area

on the performance or a r action turbine may be drawn

(1) The effect ot a variable draft tube tlow area 1a

generally favorable upon the operat1Gn ot a reaction turbull

bine because or the tendency tor the line or beat speed to

rotate toward the line ot operation This resulte in

better performance of the turbine at partbullloads

(2) he etf1o1ency eh111 tor the turbine beeomaa JDore

tlat at the top leading to a smaller max1JilWD effic1enc7

but e reater etticieney at other pointe of operation with

the insertion ot an auxiliary control ror the rate ot tlov

in the draft tube

(3) The power output of the turbine will increase at

over speed over gate conditione as well a at part gate

conditions with the proper amount or draft tube eonatr1cbull

tion or flow

(4) It is possible to eliminate at least partially

eddy type shock loss by tho introduction ot flow control

in the draft tube

BIBLIOGRAPBl

1 Addison Herbert A treatise on applied h-draul1cs New York Wiley 1954 724 Pbull

2 Allen o M and I A Winter middot Co111parative testa on experimental draft tubes Tranaact1ons ot the American ociety ot Civil Engineers 87t893bull970 1924

3 Barrows a E Water power engineering 3d ed ew York McGraw-Bill 1943 791 Pbull

Bovet G A Modern trenda in hydraulic turbine design4middot in Europe Tranaactions of the American Society ot Mechanical Engineera 75975bull993 1953bull

s Oreager William P and Joel D Justin Hydroelectrichandbook 2d ed New York Wiley 19$0 1151 Pbull

6 Daily Jamea w Hydraulic machinery Int Hunter Rouses Engineering hydraulics Hew York Wiley 19$0 p 8$8bull99

Daughertybull Robert L Bydraulie turbines ew Yorkbull7middot MoGrav-Hlll 1920 281 Pbull

8 Daugherty Robert L Inveat1gat1on of tne performance ot a reaction turbine ~anaactiona or the American Society ot Civil Engineers 7811270bull1304 1915

9 Davie L M Model and prototype testa Int Trend in hydraulle turbine practice symposium lranaactions ot the American Society ot Civil Engineers 1o63S3middot368 1941

lfJ Doland James J Hydro power engineering Hew Yorkbull Ronald 1954 209 Pbull

11 Gandy Theodore s and Elmer c Schacht Direct curshyrent motor and generator troubles operation and repair New York McGraw-Bill 1911 293 Pbull

12 Gibaon Arnold H Hydraulics and ita applications5th ed London Constable 1952 813 Pbull

58

13 Button s P Component loases in Kaplan turbinebull and The prediction of efficiency from model tests Probull coedings of the Institution or Mechanical Engineers168743-762 1954

14 Knapp R T~ Oavit t1on mechanics and its relation to the d sign or hydraulic equip ent Proceedings or tne Institution ot Mechanical Engineers 166150bull16) 1952

15 Langsdorf Alexander s Principles of direct curHnt mach1nee 5th ed New York r~cGrawbullH1ll 1940 746 Pbull

16 Lsrner Chester w Characteristica of modern hydraubull lie turbines Trans e~ions of the ~~erican Society ot Civil Engineers 66306-386 1910

17 Linsley Ray K Jr and Jobulleph B Franzin1 Eleshyments of hydraulic enginebullring New York McGrawshyBill 19$5 $82 Pbull

18 Mead Daniel w Hydraulic machinery llev York McGraw-Hill 1933 396 Pbull

19 ead Daniel w Water power engineering New York McGrawbullRill 191S 843 Pbull

20 Mockmore Charles A Part gate operation at water turbines Corvallis Oregon State College Department ot Civil Engineering 1933 11 numb leaves (Unpubshylshed typescript)

21 Mockmore Oharles A Flow characteristics in elbow dratt tubes Transactions of the Amez-ican Society ot Civil Engineers 103402middot464bull 1938

22 Moody L F Hydraulic machinery In c v Davis Handbook ot applied hydraulics New York McGrawshyHlll 1942 1082 Pbull

2) Ptau At-nold Hydrbullulie turbine handbook ld ed Milwaukee AllisbullOhalmers ManufactUIing Company 1948 70 Pbull

RheingalUI w J Recent developments in Francis turshybines Mechanical Engineering 74189-196 1952

25 Russell George E Hydraulica 5th ed New York Henry Holt 1942 466 Pbull

26 Safford A and E P- Hamilton American mixed tlow turbine and ita setting Tranampactions or the Amerieal Society of Civil Engineers 851237bull1)56 1922

27 bull Spannhake W1lhe1Dh Problems or modern pump and tur b1ne design Transactions of the American Society of Mechanical Engineers 56e22$-248 1934bull

28 Sutherlandraquo R A Better ethod or representing and middot tudying water turbine performance ~ansaetions ot thmiddote American Society of Mechanical Engineers 68t675bull 686 1946

29 Teats ot five models or draft tubes tor turbines Engineering News-Record Pbull 182-184 Aug 2 1923

30 White w M American hydztaulic turbines Mechanical Engineering S2t390bull39S 1930bull

31 White w M lhe hydraucGne rega1ner1 its developmentand appl1eat1ons 1n hydroelectric plants Meohanlobulll Engineering 43t37Sbull380 1921 middot

32 Winter I A Economic principlebull in designbull Int Trend in hydraulic urbin practice bull a ampoeiumTranaaot1ona ot the American Society ot Civil Engineerslo6332bull3S2 1941

33 Wiel1cenua G F Fluid mechan1ca or turbo-machineryNev York McGraw-Hill 1947 613 Pbull

APPENDICES

c

Appendix A

NOATIOB

A Angle between the absolute velocity vector and the tangent to the rwmer Subscripts 1 and 2 refel to entrance and exit ot the runner blade

B Angle between the relative 1elooity vector and the tangent to the rwmer Subscripta 1 and 2 refer to entrance and ezit or the runner blade

Angle between the tangent to the runner blade tip and the tangent to the runnel- Subscripts 1 and 2 reter to entrance and exit of the rt1rmer bladebull

Blade angle-gate opening conetant defined by equation (1)

e 09erall efficiency

g Gravitational acceleration assumed constant at 322 teet per second per second bull

H Turbine head detined by equation ($)

m Exit loss coeft1e1ent

Turbine speed expressed in revolutions per minute

Turbine speed under a constant head of 81 teet

specitic apeed of the turbine under a constant head ot 81 teet

p Power output in horsepower ot the tvbine

Power output of the turbine Ulder a constant head ot Sl teet

Pl- Pressure head at entrance to the tUlb1new

l1 Peripheral velocity ot the runneP Subacr1pta 1 and 2 refer to entrance and exit ot the JUnllampr blade

62

v Relative velocity reaulting trom the combination ot the absolute water velocity V and the runner periphshyeral velocity u Subscripts 1 and 2 refer to entrance and exit ot the runner blade

v] Relative velocity vector necessary to produce a tanbull gential entry into the runner blades

V Absolute water velocity Subscripts l and 2 refer to entrano and exit ot the runner blade

v2 Velocity head Subscripts 1 and 4 reter to the ~8 entrance to the turbine and the tail~ace wate~

w Unit weight ot water assumed constant at 624 pounda per cubic toot

V Weight rate ot flow in pounds per aeooncl

XX Velocity component ot ahook See Figule 2

Z Elevation head Subscripts 1 and 4 reter to entrance to the turbine and the taibace water surfacebull

Appendix B ORIGINAL DATA-Run

lfwnber

0-4-1 0-4-2 0-4-3 o-4-4 o-4-S o-4-6 0-4-7 0-4-8 0-4-9o-4-lo o-4-11 o-4-12 0-4-13

o-6-1 o-6-2 06-3 o-6-4o-6middotS o-6-6 o-6-7 o-6-8 0-6-9 o--6-lo o-6-11

Speed

rmiddot2middotbullmiddot(1)

336 38$ 451 S$9 620 669 6lt)$ 120 787 860 932

102imiddot109 bull

352 355 443middot 543middot 620 654AJs32

911 1001 1111

~essure Head rt (2)

410 410 416 426 431 43-7 439 44-9 452 467 482 soo $1 bull $

350 351 35middot7 )66 37-9 37-9 392 41 bull 3 43middot3 460 489

Elevation Bead

fjj $7 $7 $7 $7 $7 $7 51 57 5-15858 $8 58 56 56 $6565656 51 575As5a

Velocit Head

flj 07 07 07 06 06 06 06 os 05 os0404 03

09 09 oa o8 o8 os 07 07 06 o~o

Total Head rt ($)

47middot4 4A44 o 489 49-4 soo $02 $11 $14 $29 5imiddot45 2 576

41 bull $ 416 421 430 44middot3 44middot3 456 47-7 496 523551

Plow

lbtjec

326 324middot317 311 306 30029middot28 middotmiddot middot 386 275middot260 240 218

359 36~35 bull 349 345middot 339 330 318 300 273 240

Line Potential

vyqjbull 1060 1220 ~-0o 1920 2150 2000 2$60 2000 1940 18)015io11 o

1000 1100 139bull5 1760 1925 16$0 1620 1610 1540 1330 870

Line Current

amlscs 960 900 830 740 730655 70bull 0 530 660 600 5imiddot54 6 )60

982 930 860 780 ~3-545

79-5 74-5 670 560 370

P

Appendix B ORIGINAL DATA (Continued)

Run Number

Speed

Pbulltmiddotbullmiddot )

leasure Head ft(2

Elevation Head tt(J)

Velocity He-dfmiddotj

Total Bead tt($

Flow

lbstsec( )

Line Potential vo~ta( )

Line Current

amjs (sect

0bulllt)-1 0-9-2

3ll6 398

28o ~~1

$6 56

1o 10

346 347

390 365

1ooo 1190

aao 835

0-9-3 0-9-4 o-9-S

472 565 632

292 305 312

$6 s6 56

10 o9 o9

)$8 J7~o 37~7

381376 37o

1)6614oo 141o

820 ass ass o-9-6 0-9-7 0-9-8 o-9-9 0middot9-10

680 120 762 844 920

)24337346 366 390

56 $6 56 57 $7

09 os o8 oa 07

)89401 410 431454

367~ 357348 34o 322

1400 1J6o l36o 1310 1170

843 820 7957So 67~0

0-9-ll 0-912

1001 1100

41 bull 7 45-3

s 7 6~0

06 os 480 $18

299 268

980 65$

560 36~5

1-4-1 1-4-21-4-l1-4shy1-4-5 1-4-6 l-4-7 1 4-8 1-4-9 1-4-10 1middot4-ll 1-4bull12

354middot452 562 62q 674shy102 752 760- 863 932

1022 1100-

)82389 4014oa 416 41--7 423 428 44-2 45-7 486 49-2

51S757 51 5-7 5middot15zs sa $8 58 59

07 07 06 06 06 06 06 os o bull o 04 o J

446 45-)46middot4 471 ti7-9480 q86 491505 $19 548 55-4

)28 320 311 306 300 295 291 286 269 2582iimiddot21 bull

1080 14Lo 1550 153-5 1470 141-0 1385 1310 1310 1230 1120 855

970855 875 91-0 94~0 975 966 995 860 77-S 610 4fo

0 ~

Appendix B ORIGINAL DATA (Contirmed)-Run Speed Pressure Elevation Velocity Total Flow Line Line

Number Head Head Head had Potential Current rtjjmbull t~ bttec vyfs am~a12) ( ) ti fli 8

1-6-l $6 33$ $6 0bull9 400 364 1100 93 0 1-6-2 41 34laquo2 $6 oa 406 JS7middot iios a5s l-6-3 500 3~0 5bull6 os 356 1 1 o aos 41middot~1-6~4 35bull4 5-6 oa 41middot 352 16~0 82 0 5~1-6-5 5 bull 36_2 Sbull6 08 42bull6 349middot 161 ~ 0 86~0 1-6-6 622 366 $6 oe 43bull0 345middot 158 0 88~$ 16-A 649bull 37bull1 56 os 43-S 342middot 1570 895 1~- 386 57 07 46-0 192 ) 125A44 333middot 1-6-9 3) 404 5middot1 07 468 317 1620 675 1610 911 42-4 5-7 o6 48-7 298 168 0 61 0 1-6-11 999 451 56 os Sl ll 276 ~2-0 530 1-612 1115 485 58 04 54middot7 238 90 )3 0

1middot9-l 355 279 56 10 )45 385 1040 870 1-9-2 399 28J $6 10 )49 38$ 1140 86 5 l-9-3 ~ ao 291 56 ~0 35middot1 J8J_ JJ6o 815 1bull9-4 579 303 56 09 )68 375middot J4JO 830 l-9bullS 40- 313 )6 09 31middot8 370- 1460 82~0 1-9bull6 679 2) 56 09 3 bull8 364middot 1670 710 l-9-7 682 319 56 o9 384 ) 62 1460 79 5 l-9-8 724 33middot5 56 o8 399 3$6 bull 1480 76 -5 1-9-9 762 34middot3 $6 0 bull 8 407 )48 14910 13middotS 1-9-10 833middot )60 5middot7 os 42$ 339 144$ 686 1-9-ll 926 39middot1 5-7 07 455 318 1290 600 1-9-12 1000 41middot3 0-6 476 298 1115 510$ ~ 1middot9-13 1105 452 s o4 $14 2$6 710 )10

~

Appendix Bt ORIGDIAL J (Continued)

Run Speed Pressure Elevation Velocity Total Plow Line Line Number Head ltead Head jlamp$d P()ten~ibulll Current

r~~~m ft ft lbs~seo voltattj rgj twimiddot t 1 t2gt lt3 ou t ( rt

2-9-1 384 289 S 6 10 35 5 1400 1170 810 2-9-2 443middot 29$ $6 ltimiddot9 360 379middot 11(0 87$ 2-9-J 536 30bull 3 sc 09 )68 374middot 1)40 84 bull) 2-9-4 571 306 $6 09 3~1 372 120bull 0 955 2-9-5 623 316 S6 09 J l )6S UJSo 77$ 2bull9-6 669 327 S6 09 )92 )61 1240 905 2-9bull7 712 )39 56 os 40-3 351 12(0 86 bull0 2-9-8 ~5$~ J48 56 oa 412 348 1290 81 bull ) 2-9-9 04 )63 56 oa 42-7 339 12ltJO 76$ 2middotmiddot9-10 8$2 376 5middot1 07 440 33~- ~ o 710 2-9-11 955 394 5-1 o6 457 300 1100 506 2middot9-12 1000 421 $7 06 48middoti 295 1020 $18 2-9bull13 110~ 463 56 05 $2 267 620 3~0

oshy0

Appendix Gt CALCULATED DAgA

Turbine Run Generator Generator Turbine Turbine Efficiency Turbine Turbine Specit1c

Number OutputKWlt21

Loa~Jes KWlol

Outut K bull (H)

Input RP 12)

middot Percentlt13gt

Speed r~Jmiddot(

0ltput HP ~1

Speed r-m

( 6) middot

o-4-1 0middot4-2 0-4-3 0-4-4 0-4-5 0-4-6 O-qmiddot7o-4-8o-4-9 0-4bull10 0-4-11 o-4-12

1018 1o9a 1220 1)62J40214oa1J4oo 1357 1320 1164 997 718

046 o59 071 092 096 1071oo 134 104 100 109 107

14261sso 17)01948 2008 20322011 1999 19 09 1708 14-84 11o6

281279 27-7 276 215 273271 268 268 26h 258 24-5

soa 555 62$ 705 7)1145 742 74-6714645 51s 45-1

440 sos 585 720 195 sso sao 9$$ 985

1065 1135middot 1230

318 357 319 416 422 419412 39middot9 378 324 260 191

102 12bull4 148 191 21bull 3 22o 233 249 24924middot9 238 221

0-4middot13 418 104 699 228 306 1300 117 18)

o-6-1 982 045 1376 271 $08 496 376 124 o-6-2 o-6-3 G-6-4o-6-5 0-6-6

1023 1200 13 73 J415 139h

051 0middot66 oaa ()bull 96 088

14-39 1696 1958 2026 1986

276 27middot4 273 278 274

$20 61 8 717 7)0726

q95615745 8)5685

390 ll5middot3 sos soo 490

127 170 218 243 2$$

o-6-7 o-6-8 o-6-9o-6-lo

1288 1199 1032 7-45

o9o 094 09$ 096

1846 1733 1511 1128

274 276 271 260

67S 629559 43middot4

980 1085 1165 1245shy

436 )83316 21bull 7

266 276 270 239

0-6-11 322 1oo 566 2141 2JS 1350 101 177 0 --4

Appendix C CALCULATED DAlA ( Continued)-Run

Number Generator Generator

Out2ut Losaes xw LW- 12gt (lO)

Turbine Out2ut

ltPlJ

Turbine Inat lfP Jig)

Etpound1e1ency

PireentDl

Turbine Sed x-~m( 1

Turbine OutEut RPJl)

Turbine Specific

SeeedrIbullntbull

( 6)

o-9middot1 0-9-2 0-9-3 o-lt)-4 09-$ 0bull9-6 0-9-7 0-9-8 0-9-9 0-9-10 o-9-11 0-9-12

aao 994

111$ 1197 1206 1180 11)21081 982 784 5-49 2)9

0middot45oss o6$ 070 07$ 0-77 (l77 or~ o s06o 8 096

123~ 1402 1$80 1698 17bulllS 168$ 16bull18 ~middot5430 1151 a~J4 9

24middotgt24middot3248 25~25 260 260 259 267 266 26middot1 2S2

sos 577 63-7 671 676 650 621 60036J4

327 178

$) 610AlO 3$

92S 980

102$ 1070 1157middot 1230 1300 137Smiddot

44middot4 soo 523 ssomiddot 540so6 46-5 432 368 274 18~8

J46 176 21-1 255 2802s_A 28 289 288 265 231 168

1-4-1 1-4middot2 1-4-3 1-4-4 1-4-5 1-4-6 1-4-7 1-J-8 1-4~9 1-4-10 1-4-11 1-4-12

10bull48 1231 13-S6 1397 1)821375 1))8 1303 1127 953 683) 51

048 067 o7A07 0 bull79 oa1 oss o bullao osa 0lt)0 096 099

J468 1740 1921 1978 1958 19$1 1911 lSSi162 1)98 1045

603

266 264 262 262 261 2512$7 2$6 24middot7 24-3 233 217

551 660 13middot3155 75-6 7~-97 middot4 72$ 67 51middotJ 44middot9 21middot1

475 605 A4220

875middot 910 970_

1000 1090bull 1166 1243 1330

5816

44middot444middot5 430 427 412 392 329 273 188 l0-7

117 101 204 22$ 2)7245 2562sa 257251 222 179

a-C))

Appendix Ct CALCULATED -DATA ( Ocntinued)

1-6middot1 1023 o$2 14-41 26S 505 41~6 26~

54middot5 13middot3l-6-2 1201 067 1boo 625 47-9 17shy~middot41-6bull3 1296 oA9 1 middot43 26 9 700 so5 20bull 4 l-6-4 l3j5 o 0 19~09 268 71bull3 A5o 514 222 1-6-5 1) 5 o81 19(gt4 271 725 51-5 238 l-66 1398 081 198) 27-0 736 8 S13 252~-middot l-6j 1405 083 199i 211 733 885 $middot06 2$9 l-6 13middot9~ 103 2amp 0 279 71 8 985~ 467 ~-69 1228 1 bull 02 17-SS 270 661 109$ 407 ~3~ l-6bull10 1025 100 lSll 26i 573 1175middot 27~S32middot~l-ampu 153 1-00 llft3 26 444 1270 22 24bull8 1bull6-12 294 100 52a 231 22 3 1360 95 172

1-9bull1 904 048 1275 2J4Z $28 S4$ 459 1$2 1-92 98$ oss 13-92 24middot4 57-0 6JO 49bull1 176 1-9middot3 1110 066 1$76 24middot9 63middot4 I2o 536 21-7 l--9-4 1187 072 1685 251 66$ 5 $$ bull 0 261 1middot9-5 llltJ7 1710 25middot4 67-3 93$ 536 28~20-671middot9-6 1186 o 8 1708 25-7 67) 980 $15 2691-9- 1161 oBo 1660 2$middot3 6$6 990 508 29-1 l~- ll-32 oB) 16sect0 2$8 632 1030 471 291 1-9bull9 109$ oa5 2$7 614 1075 29S~middot 0 4imiddot41-9-10 9~91 oas 262 S$1 1150~ 3 o 292 1-9-11 o9o u57 12JiO 21gt 26-77middot74

-45 26sect ~middot91-912 $69 091 sas 25 middot3 1)0$ 196 2J-8 1-9-1) 220 098 426 2)9 178 1390middot 84 16 6

0 0

Appendx C CALCULATED DATA (Continued)

Turbine Run Generator Generator lurbine Turbine Eft1e1eney Turbine lurbine Spee1f1c

Number Output Losses Outit Input Speed Output SPed middot k_-V KW R _ H_bull_P Percent r Thm HP rpm_ (9) tlo) 11) middot (12 _) (lJI ( ) (1$ (14)

2-9-1 9--46 055 1)62 258 528 580 164 2-9-2 1024 056 248 58 4 665 4 9 191iimiddot48 4~middot0 2-9-3 1132 067 05 2$0 641 795 52q 237 2-9-4 1148 065 1027 2$1 -~8 845 525 252 2-9-5 11 77 oso 16-83 253 6 910~ 522 270 2-9 6 1122 071 1600 251 622 960 47-5 2722-9-A 1092 015 1562 257 608 1010 445 2z12bull9- 1052 079 1514 261 580 1060 41middot7 2 2 2middot9-9 986 o82 ]429 26) 542 1105 372 277 2-9-10 915 086 1340 268 500 1160 334 27-6 2-9-11 638 087 972 254 )81 1270~ 229 250 2-9-12 )28 090 828 259 )19 1295 179 226 2-9-13 192 094 383 2$ 6 150 1370 7 3 152

-3 0

Page 22: The Effect of A Variable Draft Tube Flow Area on the

l$

the flow and gate exit angle Since it is improbable that

d1~ect1on could be controlled at any location other than

where the gatea are situated in current turbines it will

be assumed that guide vanes will be necessary regardlesa or the method used to control the rate of flow

The primary purpose ot th se guide vanes 1s that or control over the direction ot the incoming water They

should be free to rotate in much the same manner as ordibull

nary wicket gates in order to exercise control over th

turbine speed

If the rate ot tlov is to be controlled elsewhere it

must be modified either in the penstock or the draft tube

Devices that could be used are standard valves gates

variable orifices variable venturi sections and associated

flow regulating schemes

Alauming it were decided to locate such a device upbull

stream of the turbine it would be necessary to allow disbull

tance tor the flow picture to become reestablished prior to

entry to the turbine A contused flow making transit of

the turbine passages would only contribute additional loesbull

ea Such a distance allowance would be perbapa 20 to So

diameters (2$ Pbull 119-123) In large penstocka th1a would

repreaent a considerable distance Which from the viewbull

points ot convenience and control would be undesirable

Attempts to ascertain the effect or additional tlov

16

reduc ion at the wicket gatctsmiddot wae ade 1n the lfadraulioe middot

Laboratory of Oregon St middot te College in 1933 (20) Three

d1tterent thode ot reducins the tlow were t~ied

(l) Locking in the cloeed position pairs or wicket

gatea located opposite to eaeh o~er on the -periphery ot

the wheel

(2) Locking adjacent gates in an open position by

inserting blocks of wood between them and

()) Suocess1vely looking adjacent gates in the closed

position

The results indicated a arked reduction in both power

and efficiency when compared to the curves tor normal gate

operation However it was demonstrated that it was poae1bull

ble to ahitt the power and tfieiency curve ill relation to

turbine apeed lbis important feature will be diacussed

later

ihe main conclusion of the investigation was that conbull

trol by the conyent1onal wick t gates was auper1or to other

methode egtt control exercised at the gates the aelvebullbull

It would app$ar that the bebullt location tor flow conshy

trol would be in the draft tube since none of the objecbull

tiona prev1ously mentioned wou~d eziat there

As bas been stated previously the sole object or the

17

18

turbine is to produce power as etfic1ently as possible

The equation tor the power output of a turbine () Pbull 227)

PaWHe HP (4)55o bull bull Assuming the head 1a constant and a g te located in

the draft tube decreases bhe rate ot flow the power eu

only be increased if the etticiency increases

The ettective head Gn the turbine 1s conventionally

d r1ned as the difference between the auma ot the elevashy

tion head pressure head and velocity head at the entrance

to the turbine casing and the tailrace ($ Pbull 872)

lt ie recognized that the theoretical treatment ot

shock loss as given is highly approximate and serves only

to dictate certain trenda For example the area at xit

rom the wicket g tea CfUl be measuPed with some exactness

but there exists no guarantee that the wateP particles will

complet-ely fill the apace oz- will exit at the establiahed

g te angle The same can be said of the exit trom the

runner blades AssUIlptiona were implied which would indishy

cate that all water particles passing a given croea section

ampH traveling at the same velocity in the same direction

the e alone are autt1c1ent to show 11m1tationa in a theoretbull

1eal approach to the problem

Assume a turbine with ordinary wicket gates tor oonbull

trol compared gainst the same turbine with a gate in the

18

draft tttbe tor supplampment1ng control or the rate ot rlow

Let it also be assumed that the two turbines are opershy

ating at the same point It 1s desirable to predict relabull

tive performance of the two turbines 1 this point of

operation is such that edd7 s hook loss ot reasonable proshy

portions is present in the fir t turbine

~ tull erteot of the shock loss will be exper1 need

by- the fir t turbine

lhe second turbine will derive certain advantages 11

the gate in the draft tube is adjusted to reduce the tlov

1n the proper amount Since they vary a the square ot

the veloo1t7bull the lossabull in the aeroll case wiomiddotket gate

and runner passages will decx-ease aetet-r1ng to Figure 2 1

it can be seen that a decreased velocity v1 w-ill reduce the

eddy shock losa

The ent loss in the dJtaft tube of the second turbine

will be the sum ot the tr1ct1onal loss and the velocity

head at ex1t The velocity head dissipated will be greater

due to the closing action or the gate but the reduoed

t~ictional loss which ia a tunction ot the rate of tlow1

will partially balance this

It 1a entirely possible that the net reduction in

losses in the second turbine will lead to a greater ettibull

oiency and more power output than 4eYeloped by the first

turbine

19

In Figure 3 the plot ot power output against turbine

speed for Curv A~ represents the typical family of curvea

tor a reaction turbine Th b st sp ed is the locus ot

points connecting maximum eft1oiency at each gate opening

The operating speed is the coZUJtant turbine apeed which

passes through the point ot maximum efC1ciencr of the turbull

bine The plot of turbine efficiency against power output

for Curve A is also ahown

It the turbine with flow regulation in the dratt tube

oan demonstrate superior power and efficiency at part loads

the effect would be the same as a shifting or the power

curves toward the condition shown fop Curve B 11 Thisbull

illustrates th ultimate case of the uperpoait1on of best

and operating speeds It will be noted that the pet-form~

of the turbine ot Ourve Bu 1a better than that of CUrve

A at part loads because of ita ability to sustain a relabull

tively high etticienoy ovel a Wider range of power output

o Reguireaegts tort Test Velitication

It is desired to deterra1ne the effect on the turbine

performance b) the addition of a gate in the dratt tube

Th step in the teit will bet

(1 To determine the power output and efficiency ot

the turbine tor wicket gate settings above and below rated

conditione for a wide range ot speed

20

CURVEAbull

TURBINE SPSBD TURBID SPEKD

POIBR OOTPOl

Figure 3 - Turbine Performance Curves

21

22

(2 peat (l) with the gate installed in the drat

tube

(3) middot Converting middot all data to a constant head compare the

powere and effioiencies at the same wicket gate setting and

turbin speed tor the two cbullses

If the ddition or the gate indicates an improvement

in power output and efficiency and the powe~ curve shifts

to the right along the turbine apeed scale the advantage

ot draft tube con~ol of the flow will hav been demonshy

strated

Chapter IV

A E9J11pment

ih turbine used in this test is lJ 5 1nch Pelton

reaction turbine with a rated output ot 30 horsepower under

a head of 56 feet at a speed ot 720 reYolutiona per minute

Views of this turbine are hovn in Figures S and 6 The

turbine is installed on a concrete pad located over an open

channel in the Hydraulics Laboratory at Oregon State Colshy

lege The date of manufacture of this turbine was 1915

The water was delivered to the turbine from a sump

reservoir by two pumps operating 1n parallel Each pump 1a

an 8 inch Pelton double suction centrifugal pump witb a

rating of l$00 gallons per minute at a head ot 75 teet with

a speed ot 1175 revolutions per minute Tbe inlet tlange

ot tne turbine is $pprox1mately 18 feet above the center

line of the pump

A direct current generator was coupled to the turbine

to receive tne power d veloped as shown in Figures 4 and 7 The generator is a Spr gue Electrodynamometer rated at SS horsepower with a speed range of 7$0 to l$00 revolut1one

per minute The classification is type LO 26A 2)0 volta

Figure 5 - View of Test Turbine

Figure 6 ~ View of Test Turbine

and 149 amperes lbe generator ti ld was aepar tely

excited using direct current from a motor g n r tor ampt

(l$ p 4~8)

The power output of the generator waa dissipated in

the water rheostat (3 p 488-489) shown in Figures 9 and

10 The galvanized tank contain d water ot variable d pth

on an electrode ot cast iron m aauring 1bull x 1 x 1

In the initial installation of the turbine it was

intended that the power output should be measured with a

Prony brak bull For th purpoa68 or this teat it was decided

that the brake was too instable and the generator was

substituted The platform for raising the generator the

nee asary two teet for alignment was built out of available

material In this case heavy laminated wood blocks reiashy

torced with other timbers were used and bolted through the

concrete deck (11 Pbull 36-$7)

Due to the light concrete deck the lack ot mas in

the platform and the slight misalignment in the flexible

coupling ao e vibration waa encountered It seemed to

ncr aae linearly to a maximum at the speed of bout 750

revolutions per minute Above this speed no vibPation was

noticeable The vibration waa not se~ere and does not

appear to have materially affected the test results

26

B Intrumentat1on ~ eaeur1ng Devices

The pressure head at inlet to the turbine vaa meaave4

bymeane ot two )6 inch waterbullmeroury manometerbull connected

in series as shown in Figure 8

The terminal voltage ot the generator vas meaeured by

a laboratory voltDleter with a range to )00 yolta and callbull

brated to within 15 Yolta

The armature current bull and hence the line current was

measured by a laboratory ammeter with a range to 150 amperea

and callbrated to w1 thin o 7S amperes

Tae rate ot tlow was established by weight and time

meaeurementa The weighing ank has a capacity ot 121 000

poundsJ the weight belng indicated by Toledo direct reading

scales Timing was done with a hand atop watch with clivibull

aion ot 02 second

he ~ater level in the tailrace was dete~1ned by a

hook gauge lhie was read to the nearest 001 toot

The turbine and generator speeds were eaaured by a

hand tachometer The technique of almost cont1nuoua readbull

ings of the speed gave an error ot no more than 5 revolubull

tiona per minute

c Operational Procedure

Atter the water level in the aump was checked to

insure an adequate auppl7 the puapa were primed and

27

Figure 7 - Test Generator and Plattorm

Figure middot8- Instrument Board and Field Rheostat

28

started After venting they were valved for operation 1n

parallel

The motor generator set was started to supply the

field current and the circuit breaker was closed Water

wa added to the water rheostat to the level shown in

Figure 10 ~ field current wae minimized by cutting in

all the f ield resistance in the field rheostat of Figure 8

The l2 inch gate valve shown in Figures 5 and 6 waa

slowly opened and the turbine and generator brought up to

speed The 12 inch gat valve and turbine were vented and

the pumps were checked to insure neither had lost ita prime

lhe water rheostat offers very steady load 1f the

water level is essentially constant and the water temperabull

ture 1a fixed () p 488~89) In order to maintain this

constant temperature it was decided not to circulate the

water in the rheostat but rather to allow the water to

boil thua achieving the desired result A standing wave

was set up on the face ot the electrode by the boiling

action but a atable load was eatablished except at very

low water leYels where th11 agitation led to fluctuationa

in the line current

After putting the turbine and generator on the line

maximum power was dissipated in the rheostat by redueing

the turbine speed to between oSO and Soo revolutions per

minute Salt vas added to the rheoetat wat r to increasemiddot

29

Figure 9 - View of Water Rheostat

Figure 10 - View of Water Rheostat

Separate Field ExcitationFrom Motor-Generator set Compound Water-Mercury

---shy

re Manometer

I Q)

~ 0

~

Book Gauge

Open Channel

I

Slap Reservoir

Figure 11 - Wat~r Flow Diagram and Electrical Layout

31

waiting pe~iod ot perhaps an h~ followed

while the boiling point or the water wbulls reacbe4 During

this ti+ne the manometer was vented end eheoked electrical

measur1ng 1nstlUments were connected end the hook gauge was

adjusted tor elevation

It required about two- houtte tor the generator to reach

its normal operating tempe-ratu~e_ After the water in the

rheostat and generator had reached their operating temperabull

turea it was possible to begin the taking of data

The only vaPiable which was controlled wee the turbineshy

generator speed However the upper l1ut1t of safe line

current was slightly over 100 ampJilPampPes and the eireuit

breaker would open when the current reached lOS ~ere bull

Control was exercised by means ot regulating the water

level and salt 1n the water rheo tat and the res1stsnoe of

the tield rheost t~

The etfeet ot each type ot regulation on the three

variables is shown below

Volta Aaperebull Speed

Inc Dec Inc Dee~ Inc Dec

Wa~e1 Level Inc Dec~ X

X X X X

X

Salt Concentration

Inc Dec X

X X X X

X

field Resistance

Inc Dec

X X

X X

X X

32

Jlot all methods gave the ame amount ot change in a

given variable and a period of experiment and trial led to

the following scheme starting the rune with the lowest

turbine speed the water level was high with a high amount

ot salt and the field resistance was cut completely out

Aa it became necessary to increase the speed tor each

aucceasive run either cutting in t he field resistance

decreasing the salt concentration or lowering the Vater

level would produce the desired result However decreasbull

1ng the salt concentration had to be done Without a net

gain in water which led to a tluahing procedure that was

not particularly good because cold water was introduced

which required time to heat to the boiling point Cutting

1n additional field resistance was a good method but th1a

increased the amperage possibly to the point of opening

the circuit breaker Lowering the water level was aatiashy

factol1 until the level got too low causing the current

fluctuation previously mentioned Actually it turned out

that a combination of lowering the water level and cutting

field resistance in would carry the speed from ita minimum

to 1ts maximum value it the proper choice were made each

time the speed waa to be changed At the conclusion of

each aet of runs at a high speed the water level would be

low and the field resistance high

33

TURBINE

PAD AND DECK

TAILRACE

WATER SURFACamp

CONCRETE

DRAFT TU1B INSERTS

7 5( DRAFr TUBE

FLltJI ARIA

5~ DRAFT TUBE

FLOI ARSA

Figure 12 - Sketch of Draft Tube and Test Inserts

34

Figure 13 - View of Draft Tube Insert

Figure 14 - View of Draft Tube Insert

D c __ ~s_middot hedu_le of

A number was assigned to each run The fi~st number

applies to the draft tube tlow areas

1 bull 100~ flow area or 0~ oonatriction

2 - 7S tlow area or 2$ conatr1ct1on

3 SoC flow area or so~ constriction

The second number refers to the wicket gate openings

9 over gate opening

6 bull intermediate gate opening

4 bull one h lt gate opening

The third number 14entif1ea the location of the particular

1Wl in a set ot rona made at a given dratt tube tlow area

and wicket gate opening

fnua run number 1bull4bull10 would identity this as the

tenth run ot a set made at halt gate with 75 ot the draft

tube t1ow area

Rune w re made tor a g1yen dratt tube condition

Firat tor tull 41-aft tube flow area seta ot rune were

made for the overgate halt gate and intermediate gate

conditione An insert was placed in t he draft tube and

rune based on the same gate conditions were made tor the

7S~ draft tube flow area case The insert was then changed

to allow only $~ draft tube flow area

The inserts are sketched 1n Figure 12 and photographed

ln Flgurea 13 and 14 They oonaisted of circula~ segments

36

or l2 ineh plywood mount 4 on wooden legs 10 inches high

The 1nse7te were placed in position and secured by th use

ot a-clamps on the legs and the outside ot the bottom of

the draft tube The obvious disadvantage to this method

waa the neoeasity tor draining the water from the tailrace

tor a change ot 1naert The advantage vas of course the

simplicity ot design and construction

Chapter V

DATA-A Original Data

The normal data-taking crew consisted or two men

Assuming adjustments having been made to secure a certain

turbine speed (aee section on Operational Procedure) one

man would take semi-continuous speed readings with the hand

tachometer until a state or rotational equilibrium was

reached This could be only a period or two minutes up to

ten or tifteen minutes As soon as steady speed was

assured the data taking would begin The second man went

to the weighing tank Where a minimum ot three weighingamp

were made The requirement was to get three consecutive

readings such that the ditterence between tbe smallest and

largest time did not exceed 04 seconds The time to

collect a given weight ot water was then assumed to be the

arithmetic average of the three times He then went to the

hook gauge determined the hook elevation and then

recorded the data on the data sheets The first man meanshy

while had taken readings of the line voltage line current

and manometers and checked the turbine speed by multiple

readings During the length of the run all values were

38

checked to determine mean values for recording

The minimum length of one run was about five minutes

If one or more measure ants tended to drift during the run

all values wer discarded and a new run began as soon aa

qu111br1um was stabl1shedo

B -0-al_e_u_l_a_t--d Data

The h d on the tu~bine 1 defined by

($)

The maxtmwm velocity V4 was equal to about o8 tampet per

secon4 which makes it a negligible quantity when converted

into velocity head

An engineerbulla level was used to deterine the d1ffePshy

ence 1n elevation between the compound water-mercury manoshy

meter and the hook gauge Using this value the equation

for turbine bead becomes

where z4 is the hook gauge reading

The rate of flow 1 cent

w weight or water collected average time to collect

The inlet velocity v1 vas calculated by dividing the

weight rate or flow by the specific weight of water and the

)9

area ot ~e inlet pipe This was equivalent to dividing

the weight rate of flow by 490 Then the power input to the turbine is equal to

WHpin rri

10 (6)

Also

(P ~ut) Turbine

(P out) + Generator

(P lost) Generator

The power output of the generator is simplJ the

produot ot the terminal voltage and the armature (line)

curPent The power lost in the generator can be subdivided

into copper losses and stray power losses lo evaluate

these cunes based on losses of an identical generator

11leampsured by the Department ot Mechanical Engineering were

used The loss curves are reppoduced in part in Figures

15 and 16

Determination ot generator losses proceeds as tollowau

(1) From Figure 15 detem1ne the vo1tage drop in the

armature circuit using the temperatures of 1220 F and the

meaaured current

(2) The induced voltage is t~e sum of the terminal

voltage and the voltage drop 1n the armature circuit

() Entering the induced voltage and the turbine speed

into Figure 16 the stray power loss can be determined

(4) The copper lose can be evaluated from Figure 1$

using the measured current and the temperatlll-e of 1220 P

40

25 ~------~--------~--------~------~

U) -U) - 20

f-4 ~

-~ -gt 0

0

VOLTAGE DROP

~ - i -

- bullbullbull bull - -middot-middot -+ ~- + -t--+ ~ - ~ middotbull ~-~ middott- -+----- _ -4 middotmiddot- --~-+-t---r~~ ~--+t-t- - ---t-c-++~-ulf--

0 50 75 100

Figure 15 - Curves of Generator Voltage Drop and Copper Loss

41

1200

1000

800

600

800

0

0

~-

middot--~ 1shy --1 + bull l

100

I -

150 200

IIDOOED VOLTAGB (VOLTS)

Figure 16 - Curves of Generator Stray Power Loss

_ j

-bullshy -L---- shy middot -shy

250

- r

42

(5) The generator los os equal the sum of the eopp r

loss and stray power loss

~e efficiency or the turbine is taken as

etticiency u e =P out (8)Pin

~ample pound Determ1n1gg turbine Power Output

The following data are taken trom that ot Run 1-9-1

Line voltage 1040 volts Line current 870 amperesSpeed 355 revolutions per minute

The induced voltage 1a determined as follows

Line voltage 1040

Voltage drop 90 using Figure 15 with line current of 870 amperes and temperature ot 122 degrees)

Induced Toltage 1130 volta

The power output of the turbine is determined as follows

Generator output 90$0 (line voltage z line current)

Oopper loss 7 (using Figure 15 with line current of 870 amperes and temperatUe or 122 degrees)

Stray power lose 470 (using Figure 16 with speed ot 355 revolutions per miDUte and induced voltage or 1130 volts)

Turbine power output 9527 vatta

or turbine power output 1s 12z2 horsepower

43

The conversion of the calculated data to a constant

head is based on the conventional assumption of constant

efficiency regardless of turbine head For a constant head

ot 81 teet a purely arbitrary figure the tollowing relashy

tionships are ass1lJiled to be true

I ____L (9) (i)l72

(10)

For these two values the specific a peed may be combull

putedt

N t Jt VPt (11)8 243

Chapter VI

~RESULTS

A -Pr_e_ae_n_t_a_t_t_o~n g Reaultbull

Graphical presentation ot the results ot this te1t

are given as follows

Figure 17 -Turbine characteristics with 100~ dratt

tuba 1low area

Figure 18 - Turbine characteristics with 7S dratt

tube tlow area

Figure 19 bull Comparison ot power and etticiency at

over gate conditions between 100 and

75~ draft tube flow area

Figure 20 bull COZQparison of power and ettic1ency at

halt gate conditions between 100~ and

7S~ draft tube flow area

Figure 21 bull Comparison of power and etticiency at

over gate condition between 100~ and

So dratt tube tlow area

Figure 22 - Comparison in variation ot apec1t1c

speed between 100 and 75~ dratt tube

tlow area

50

45

20

-bull - 1--shy40

bull J-~ 30

~ ex

~ 20

~~ ~ -)q

I

~ - _

- -

10~ OF DRAFT TUBE FL(Jif AREA

CONSTANT HEAD OF 8l FEST10

POIER OUTPUT EFFICIENCY SPECIFIC SPEED

0 ~--------------_--------~------~------~ 400 600 800 1000 1200 1400

TURBINE SPEED (RPM)

Figure 17 - Turbine Char~cteristics with 100 Draft Tube Flow Area

50

46

-bulllle

~ 7 ~ OF DRAFt TUBE FLOW AREA

0 -~~-rl C05STAMT BEAD OF 81 mET 1J~

POIER OOTPUT ---+- ---o ~_H EFFICIDCY ~ I shy

bull ql SPECIFIC SPEKD - ~ -

bull ~ J 10 L rmiddotr- r- -

bullz- I

~~ 30 ~~--~----~~-

20 ~ ~ middot-shy

26

~~ 25

~0 ~r-----i (

Tbull -bullshy

400 600 800 1000 1200 1400

TURBINE SPEED (R PK )

Figure 18 -Turbine Characteristics with 75 Draft Tube Flow Area

47

EFFICIENCY 60

1-----shy

-~ 50~--~--~~-~middot middot middot middot r~-~----~~~~---4~-r~-~~gtt

II

POWER~ J ~ bull bull

u I

sH

40~------+-------+---- -~~--~~-~~~~

~----~rl 1 bull

I

I

0~--------------~------_------~--------

~ -OVER GATE CONDITION

COIJSTANT HEAD OF 81 FEET

0 o 10~ DRAFt TUBE

_-- _ 7~ DRAFT TUBamp FLON AREA II

10_~-----+--------r-------r----~~

400 600 800 1000 1200 1400

TURBINE SPEED (RPM)

Figure 19 middot - Comparison between 75 and 100 Draft Tube Flow Areas of Power and Efficiency at Over Gate Conshydition

48

t

bull --4 r ~- ~ middot~

70 1-----------+-~~~~~+middot ~ ~~ middot middot -~~--~~--------~~----~-+1

-~-

Atbull bull

lla-

60

amp0

40

20

10

oampOO

t _ - - ~-+- - -~-

l2 GATB COJIDITIOJJ

COJISTABT HJW) OF 81 JBET

o 0 lOQ( DRAFl TUB8 FLOI AREA

e-- - e 75 DRAFT TUBE FLOW AREA

800 1000

- r-

~

TURBIbull SPBIID (RPII)

Figure 20 - Comparison between 75 and 100 Draft Tube Flow Areas of Power and Efficiency at Half Gate Conshydition

49

60

50

-40

bull 30

IIQbull

20

10

0

400

- t - ~

EFFICIENCY

_J bull - bull bull

~ r r middot t -+ shy L -t -

OVER GAD COliDITIOI

CONSTABT BEAD OF 8l FBB

o o 10~ DRAFt TUBE FLOI ADA middot--- 5~ DRAF TUBE FLQPi AREA

600 800 1000 1200

Figure 21 -Comparison between 50~ and 100~ Draft Tube Flow Areas of Power and Efficiency at Ove~ Gate Conshydition

50

25

20

15

10

0

Figure 22

~- T -4 -t- -l --~-

t-~ I

middot --~- t ~---- _ __ _ + --

----~- --r-- --

~-=J-~-=-~ -==~ _ ~- -- ---f---1 - shy

CONSTANT HEAD OF 81 FEBT

o--o 1~ DRAFT TUBE FLltll AREA

75C DRMT TUBK FLCIJ AREAmiddot--middot-middot 600 800 1000

TURBINE SPEED (RPK)

Comparison of Specific Speeds for 75 and 100 Draft Tube Flow Areas

51

B Discussion 2 Result

Consideration of Figures 17 and 18 indicates the

overall eftioi ncy pattern or hill is significantly or

rounded for the 7$~ flow area than for the 100~ flow area

bia implies a greateP efficiency is possible at speeds

leas than or greater than design speed with an insert in

the draft tube However the muilDum efficiency is lemiddotas

Direct comparison at over gate conditions is made in

Figure 19 ~e same general trend is noted tor both the

etticiency and power curves for the 7$~ flow area case

The eurves show higher values at overspeed than do the

correaponding cWvea for the 100 flow area case It ia

not clear whether the curves have been shifted by the dratt

tube constriction or whether the curves simply bulge past

the normal curves at both overspeed and underspeed condishy

tions The power curves apparently peak near the aeme

point bullalthough maximum power is still obtained with the

normal draft tube area

For the comparison at halt gate operation shown in

Figure 20 a general improvement has apparently been made

by restriction of the draft tube flow area At every speed

the etticienoy and the power is greater for the restricted

tlow case The two ett1o1ency curves and two power curvea

are practically parallel throughout the speed range ot

teat

As the flou aroa i e decreased still farther a s1gn1

ticant change appears Reterr1ng to Figllle 211 tor the $0

flow area curves it a obvious that exit losses have

become excessive at the overgate condition because the

efficiency and power are everywhere leas than tor the case

of normal draf t tube area

Earlier it was pointed out t hat 1t the r esult s 1nd1bull

eated an increase in both power and ef tieiency- t hen it

could be assumed tha t the additional los s i ntroduced with

the draft tube insert is less than the diminished losses

due to leas shock losa and water passage losses For the

places where both the efficiency and power have been

increased we can assume that the insert has improved turshy

bine performance

For the places where the power haa been decreased

nothing can be said as to the elimination of ampbock loss

because the new lose present with the drat tube insert has

overshadowed any gains in eftecti Ve head upatJ-eam of the

insert

Near the peak of the efficiency hill howeve~ it may

be pointed out t hat shock loaa ie a minimum with a normal

draft tube and the insert merely adds an additional loss

with the resultant decrease in maximum efficiency tor the

7$~ flow area case

Perhaps the most s1gn1ticant set of eurves is shown aa

53

Figure 22 In this graph values of specific speed tor the

75 and 100~ flow area cases for both over gate and one

halt gate openings are plotted against turbine speed At

every speed and both gate openings the value ot specific

speed for th 75~ flow area case is greater than that for

the 100 t1ow area ease

Since the head is a constant for both situations this

may be interpreted in either of two ways trom equation

(11)

(1) For the same turbine apeed restriction of the

draft tube t1ow area resulted in greater turbine power

(2) For the same power amputput the turbine with 75~

draft tube flow area operated at a greater speed than did

the one with 100 flow area

Since the required diameter of a turbine varies

inversely with the speed the second interpretation could

be stated such that a smaller turbine could be used to

develop the same power output

Whether viewed trom the aspect of increased power

greater speed or reduced size the performance of the turshy

bine with reduced draft tube flow area is superior to that

with the nolmal flow are in the draft tube

The curve of specmiddotific speed versus turbine speed for

the so draft tube flow area case at over gate cond1t1ona

was not included in Figure 22 This curve lies below that

for the 100~ flow area c se at all speeds

In elaboration ot the second interpretation of Figure

22 attention is directed to the relative magnitudes ot

increased apee1f1c speed tor the two gate openings Assumbull

ing that the increase in specific speed implies a shift ot

the power curve to the right along the turbine speed scale

the power curve would be shifted more tor tbe halt gate

opening than tor the over gate opening

It thia trend could be extrapolated to the other gate

openings the tendency can be seen tor the line ot beat

speed to rotate toward the line of the operating speed as

illustrated in FigtU-e ) The advantage of this has already

been discussed

This particular turbine has a low specific speed tor a

reaction turbine Aa the rated value of apecitic apeed tor

reaction turbines increases the line ot beat speed departs

even more radically from the line of operating bullpeed It a

test similar to this were conducted on a reaction turbine

ot gleater specific speed it is pJobable t hat the rotation

ot the line of beat apeed would become more p~onounced

The scheme used in th1a teat had two obvious dr wbull

backs The first was the decision to leave all the wicket

gamiddottes installed tor all conditions ot the draft tube

These gates predominated in control of the tlow The

inserts added to the draft tube merely acted as auxiliary

55

contrGla

The aecond drawback was the choice or device to place

in the draft tube The reasons foll selection of this type

of device have been previously mentioned It is to be

anticipated that adaptation ot dratt tube flow control

would result 1n a better device for an actual turbine

installation Such apparatus might take the form of a

pneumatic bladder or a h7drau11oally operated variable

venturi section in the draft tube It is conceivable that

the gate as used in this test might be adapted also

Chapter VII

OONCLtJSIOfS

From the results of this test the following eonolubull

e1ona aa to the effect ot a variable draft tube flow area

on the performance or a r action turbine may be drawn

(1) The effect ot a variable draft tube tlow area 1a

generally favorable upon the operat1Gn ot a reaction turbull

bine because or the tendency tor the line or beat speed to

rotate toward the line ot operation This resulte in

better performance of the turbine at partbullloads

(2) he etf1o1ency eh111 tor the turbine beeomaa JDore

tlat at the top leading to a smaller max1JilWD effic1enc7

but e reater etticieney at other pointe of operation with

the insertion ot an auxiliary control ror the rate ot tlov

in the draft tube

(3) The power output of the turbine will increase at

over speed over gate conditione as well a at part gate

conditions with the proper amount or draft tube eonatr1cbull

tion or flow

(4) It is possible to eliminate at least partially

eddy type shock loss by tho introduction ot flow control

in the draft tube

BIBLIOGRAPBl

1 Addison Herbert A treatise on applied h-draul1cs New York Wiley 1954 724 Pbull

2 Allen o M and I A Winter middot Co111parative testa on experimental draft tubes Tranaact1ons ot the American ociety ot Civil Engineers 87t893bull970 1924

3 Barrows a E Water power engineering 3d ed ew York McGraw-Bill 1943 791 Pbull

Bovet G A Modern trenda in hydraulic turbine design4middot in Europe Tranaactions of the American Society ot Mechanical Engineera 75975bull993 1953bull

s Oreager William P and Joel D Justin Hydroelectrichandbook 2d ed New York Wiley 19$0 1151 Pbull

6 Daily Jamea w Hydraulic machinery Int Hunter Rouses Engineering hydraulics Hew York Wiley 19$0 p 8$8bull99

Daughertybull Robert L Bydraulie turbines ew Yorkbull7middot MoGrav-Hlll 1920 281 Pbull

8 Daugherty Robert L Inveat1gat1on of tne performance ot a reaction turbine ~anaactiona or the American Society ot Civil Engineers 7811270bull1304 1915

9 Davie L M Model and prototype testa Int Trend in hydraulle turbine practice symposium lranaactions ot the American Society ot Civil Engineers 1o63S3middot368 1941

lfJ Doland James J Hydro power engineering Hew Yorkbull Ronald 1954 209 Pbull

11 Gandy Theodore s and Elmer c Schacht Direct curshyrent motor and generator troubles operation and repair New York McGraw-Bill 1911 293 Pbull

12 Gibaon Arnold H Hydraulics and ita applications5th ed London Constable 1952 813 Pbull

58

13 Button s P Component loases in Kaplan turbinebull and The prediction of efficiency from model tests Probull coedings of the Institution or Mechanical Engineers168743-762 1954

14 Knapp R T~ Oavit t1on mechanics and its relation to the d sign or hydraulic equip ent Proceedings or tne Institution ot Mechanical Engineers 166150bull16) 1952

15 Langsdorf Alexander s Principles of direct curHnt mach1nee 5th ed New York r~cGrawbullH1ll 1940 746 Pbull

16 Lsrner Chester w Characteristica of modern hydraubull lie turbines Trans e~ions of the ~~erican Society ot Civil Engineers 66306-386 1910

17 Linsley Ray K Jr and Jobulleph B Franzin1 Eleshyments of hydraulic enginebullring New York McGrawshyBill 19$5 $82 Pbull

18 Mead Daniel w Hydraulic machinery llev York McGraw-Hill 1933 396 Pbull

19 ead Daniel w Water power engineering New York McGrawbullRill 191S 843 Pbull

20 Mockmore Charles A Part gate operation at water turbines Corvallis Oregon State College Department ot Civil Engineering 1933 11 numb leaves (Unpubshylshed typescript)

21 Mockmore Oharles A Flow characteristics in elbow dratt tubes Transactions of the Amez-ican Society ot Civil Engineers 103402middot464bull 1938

22 Moody L F Hydraulic machinery In c v Davis Handbook ot applied hydraulics New York McGrawshyHlll 1942 1082 Pbull

2) Ptau At-nold Hydrbullulie turbine handbook ld ed Milwaukee AllisbullOhalmers ManufactUIing Company 1948 70 Pbull

RheingalUI w J Recent developments in Francis turshybines Mechanical Engineering 74189-196 1952

25 Russell George E Hydraulica 5th ed New York Henry Holt 1942 466 Pbull

26 Safford A and E P- Hamilton American mixed tlow turbine and ita setting Tranampactions or the Amerieal Society of Civil Engineers 851237bull1)56 1922

27 bull Spannhake W1lhe1Dh Problems or modern pump and tur b1ne design Transactions of the American Society of Mechanical Engineers 56e22$-248 1934bull

28 Sutherlandraquo R A Better ethod or representing and middot tudying water turbine performance ~ansaetions ot thmiddote American Society of Mechanical Engineers 68t675bull 686 1946

29 Teats ot five models or draft tubes tor turbines Engineering News-Record Pbull 182-184 Aug 2 1923

30 White w M American hydztaulic turbines Mechanical Engineering S2t390bull39S 1930bull

31 White w M lhe hydraucGne rega1ner1 its developmentand appl1eat1ons 1n hydroelectric plants Meohanlobulll Engineering 43t37Sbull380 1921 middot

32 Winter I A Economic principlebull in designbull Int Trend in hydraulic urbin practice bull a ampoeiumTranaaot1ona ot the American Society ot Civil Engineerslo6332bull3S2 1941

33 Wiel1cenua G F Fluid mechan1ca or turbo-machineryNev York McGraw-Hill 1947 613 Pbull

APPENDICES

c

Appendix A

NOATIOB

A Angle between the absolute velocity vector and the tangent to the rwmer Subscripts 1 and 2 refel to entrance and exit ot the runner blade

B Angle between the relative 1elooity vector and the tangent to the rwmer Subscripta 1 and 2 refer to entrance and ezit or the runner blade

Angle between the tangent to the runner blade tip and the tangent to the runnel- Subscripts 1 and 2 reter to entrance and exit of the rt1rmer bladebull

Blade angle-gate opening conetant defined by equation (1)

e 09erall efficiency

g Gravitational acceleration assumed constant at 322 teet per second per second bull

H Turbine head detined by equation ($)

m Exit loss coeft1e1ent

Turbine speed expressed in revolutions per minute

Turbine speed under a constant head of 81 teet

specitic apeed of the turbine under a constant head ot 81 teet

p Power output in horsepower ot the tvbine

Power output of the turbine Ulder a constant head ot Sl teet

Pl- Pressure head at entrance to the tUlb1new

l1 Peripheral velocity ot the runneP Subacr1pta 1 and 2 refer to entrance and exit ot the JUnllampr blade

62

v Relative velocity reaulting trom the combination ot the absolute water velocity V and the runner periphshyeral velocity u Subscripts 1 and 2 refer to entrance and exit ot the runner blade

v] Relative velocity vector necessary to produce a tanbull gential entry into the runner blades

V Absolute water velocity Subscripts l and 2 refer to entrano and exit ot the runner blade

v2 Velocity head Subscripts 1 and 4 reter to the ~8 entrance to the turbine and the tail~ace wate~

w Unit weight ot water assumed constant at 624 pounda per cubic toot

V Weight rate ot flow in pounds per aeooncl

XX Velocity component ot ahook See Figule 2

Z Elevation head Subscripts 1 and 4 reter to entrance to the turbine and the taibace water surfacebull

Appendix B ORIGINAL DATA-Run

lfwnber

0-4-1 0-4-2 0-4-3 o-4-4 o-4-S o-4-6 0-4-7 0-4-8 0-4-9o-4-lo o-4-11 o-4-12 0-4-13

o-6-1 o-6-2 06-3 o-6-4o-6middotS o-6-6 o-6-7 o-6-8 0-6-9 o--6-lo o-6-11

Speed

rmiddot2middotbullmiddot(1)

336 38$ 451 S$9 620 669 6lt)$ 120 787 860 932

102imiddot109 bull

352 355 443middot 543middot 620 654AJs32

911 1001 1111

~essure Head rt (2)

410 410 416 426 431 43-7 439 44-9 452 467 482 soo $1 bull $

350 351 35middot7 )66 37-9 37-9 392 41 bull 3 43middot3 460 489

Elevation Bead

fjj $7 $7 $7 $7 $7 $7 51 57 5-15858 $8 58 56 56 $6565656 51 575As5a

Velocit Head

flj 07 07 07 06 06 06 06 os 05 os0404 03

09 09 oa o8 o8 os 07 07 06 o~o

Total Head rt ($)

47middot4 4A44 o 489 49-4 soo $02 $11 $14 $29 5imiddot45 2 576

41 bull $ 416 421 430 44middot3 44middot3 456 47-7 496 523551

Plow

lbtjec

326 324middot317 311 306 30029middot28 middotmiddot middot 386 275middot260 240 218

359 36~35 bull 349 345middot 339 330 318 300 273 240

Line Potential

vyqjbull 1060 1220 ~-0o 1920 2150 2000 2$60 2000 1940 18)015io11 o

1000 1100 139bull5 1760 1925 16$0 1620 1610 1540 1330 870

Line Current

amlscs 960 900 830 740 730655 70bull 0 530 660 600 5imiddot54 6 )60

982 930 860 780 ~3-545

79-5 74-5 670 560 370

P

Appendix B ORIGINAL DATA (Continued)

Run Number

Speed

Pbulltmiddotbullmiddot )

leasure Head ft(2

Elevation Head tt(J)

Velocity He-dfmiddotj

Total Bead tt($

Flow

lbstsec( )

Line Potential vo~ta( )

Line Current

amjs (sect

0bulllt)-1 0-9-2

3ll6 398

28o ~~1

$6 56

1o 10

346 347

390 365

1ooo 1190

aao 835

0-9-3 0-9-4 o-9-S

472 565 632

292 305 312

$6 s6 56

10 o9 o9

)$8 J7~o 37~7

381376 37o

1)6614oo 141o

820 ass ass o-9-6 0-9-7 0-9-8 o-9-9 0middot9-10

680 120 762 844 920

)24337346 366 390

56 $6 56 57 $7

09 os o8 oa 07

)89401 410 431454

367~ 357348 34o 322

1400 1J6o l36o 1310 1170

843 820 7957So 67~0

0-9-ll 0-912

1001 1100

41 bull 7 45-3

s 7 6~0

06 os 480 $18

299 268

980 65$

560 36~5

1-4-1 1-4-21-4-l1-4shy1-4-5 1-4-6 l-4-7 1 4-8 1-4-9 1-4-10 1middot4-ll 1-4bull12

354middot452 562 62q 674shy102 752 760- 863 932

1022 1100-

)82389 4014oa 416 41--7 423 428 44-2 45-7 486 49-2

51S757 51 5-7 5middot15zs sa $8 58 59

07 07 06 06 06 06 06 os o bull o 04 o J

446 45-)46middot4 471 ti7-9480 q86 491505 $19 548 55-4

)28 320 311 306 300 295 291 286 269 2582iimiddot21 bull

1080 14Lo 1550 153-5 1470 141-0 1385 1310 1310 1230 1120 855

970855 875 91-0 94~0 975 966 995 860 77-S 610 4fo

0 ~

Appendix B ORIGINAL DATA (Contirmed)-Run Speed Pressure Elevation Velocity Total Flow Line Line

Number Head Head Head had Potential Current rtjjmbull t~ bttec vyfs am~a12) ( ) ti fli 8

1-6-l $6 33$ $6 0bull9 400 364 1100 93 0 1-6-2 41 34laquo2 $6 oa 406 JS7middot iios a5s l-6-3 500 3~0 5bull6 os 356 1 1 o aos 41middot~1-6~4 35bull4 5-6 oa 41middot 352 16~0 82 0 5~1-6-5 5 bull 36_2 Sbull6 08 42bull6 349middot 161 ~ 0 86~0 1-6-6 622 366 $6 oe 43bull0 345middot 158 0 88~$ 16-A 649bull 37bull1 56 os 43-S 342middot 1570 895 1~- 386 57 07 46-0 192 ) 125A44 333middot 1-6-9 3) 404 5middot1 07 468 317 1620 675 1610 911 42-4 5-7 o6 48-7 298 168 0 61 0 1-6-11 999 451 56 os Sl ll 276 ~2-0 530 1-612 1115 485 58 04 54middot7 238 90 )3 0

1middot9-l 355 279 56 10 )45 385 1040 870 1-9-2 399 28J $6 10 )49 38$ 1140 86 5 l-9-3 ~ ao 291 56 ~0 35middot1 J8J_ JJ6o 815 1bull9-4 579 303 56 09 )68 375middot J4JO 830 l-9bullS 40- 313 )6 09 31middot8 370- 1460 82~0 1-9bull6 679 2) 56 09 3 bull8 364middot 1670 710 l-9-7 682 319 56 o9 384 ) 62 1460 79 5 l-9-8 724 33middot5 56 o8 399 3$6 bull 1480 76 -5 1-9-9 762 34middot3 $6 0 bull 8 407 )48 14910 13middotS 1-9-10 833middot )60 5middot7 os 42$ 339 144$ 686 1-9-ll 926 39middot1 5-7 07 455 318 1290 600 1-9-12 1000 41middot3 0-6 476 298 1115 510$ ~ 1middot9-13 1105 452 s o4 $14 2$6 710 )10

~

Appendix Bt ORIGDIAL J (Continued)

Run Speed Pressure Elevation Velocity Total Plow Line Line Number Head ltead Head jlamp$d P()ten~ibulll Current

r~~~m ft ft lbs~seo voltattj rgj twimiddot t 1 t2gt lt3 ou t ( rt

2-9-1 384 289 S 6 10 35 5 1400 1170 810 2-9-2 443middot 29$ $6 ltimiddot9 360 379middot 11(0 87$ 2-9-J 536 30bull 3 sc 09 )68 374middot 1)40 84 bull) 2-9-4 571 306 $6 09 3~1 372 120bull 0 955 2-9-5 623 316 S6 09 J l )6S UJSo 77$ 2bull9-6 669 327 S6 09 )92 )61 1240 905 2-9bull7 712 )39 56 os 40-3 351 12(0 86 bull0 2-9-8 ~5$~ J48 56 oa 412 348 1290 81 bull ) 2-9-9 04 )63 56 oa 42-7 339 12ltJO 76$ 2middotmiddot9-10 8$2 376 5middot1 07 440 33~- ~ o 710 2-9-11 955 394 5-1 o6 457 300 1100 506 2middot9-12 1000 421 $7 06 48middoti 295 1020 $18 2-9bull13 110~ 463 56 05 $2 267 620 3~0

oshy0

Appendix Gt CALCULATED DAgA

Turbine Run Generator Generator Turbine Turbine Efficiency Turbine Turbine Specit1c

Number OutputKWlt21

Loa~Jes KWlol

Outut K bull (H)

Input RP 12)

middot Percentlt13gt

Speed r~Jmiddot(

0ltput HP ~1

Speed r-m

( 6) middot

o-4-1 0middot4-2 0-4-3 0-4-4 0-4-5 0-4-6 O-qmiddot7o-4-8o-4-9 0-4bull10 0-4-11 o-4-12

1018 1o9a 1220 1)62J40214oa1J4oo 1357 1320 1164 997 718

046 o59 071 092 096 1071oo 134 104 100 109 107

14261sso 17)01948 2008 20322011 1999 19 09 1708 14-84 11o6

281279 27-7 276 215 273271 268 268 26h 258 24-5

soa 555 62$ 705 7)1145 742 74-6714645 51s 45-1

440 sos 585 720 195 sso sao 9$$ 985

1065 1135middot 1230

318 357 319 416 422 419412 39middot9 378 324 260 191

102 12bull4 148 191 21bull 3 22o 233 249 24924middot9 238 221

0-4middot13 418 104 699 228 306 1300 117 18)

o-6-1 982 045 1376 271 $08 496 376 124 o-6-2 o-6-3 G-6-4o-6-5 0-6-6

1023 1200 13 73 J415 139h

051 0middot66 oaa ()bull 96 088

14-39 1696 1958 2026 1986

276 27middot4 273 278 274

$20 61 8 717 7)0726

q95615745 8)5685

390 ll5middot3 sos soo 490

127 170 218 243 2$$

o-6-7 o-6-8 o-6-9o-6-lo

1288 1199 1032 7-45

o9o 094 09$ 096

1846 1733 1511 1128

274 276 271 260

67S 629559 43middot4

980 1085 1165 1245shy

436 )83316 21bull 7

266 276 270 239

0-6-11 322 1oo 566 2141 2JS 1350 101 177 0 --4

Appendix C CALCULATED DAlA ( Continued)-Run

Number Generator Generator

Out2ut Losaes xw LW- 12gt (lO)

Turbine Out2ut

ltPlJ

Turbine Inat lfP Jig)

Etpound1e1ency

PireentDl

Turbine Sed x-~m( 1

Turbine OutEut RPJl)

Turbine Specific

SeeedrIbullntbull

( 6)

o-9middot1 0-9-2 0-9-3 o-lt)-4 09-$ 0bull9-6 0-9-7 0-9-8 0-9-9 0-9-10 o-9-11 0-9-12

aao 994

111$ 1197 1206 1180 11)21081 982 784 5-49 2)9

0middot45oss o6$ 070 07$ 0-77 (l77 or~ o s06o 8 096

123~ 1402 1$80 1698 17bulllS 168$ 16bull18 ~middot5430 1151 a~J4 9

24middotgt24middot3248 25~25 260 260 259 267 266 26middot1 2S2

sos 577 63-7 671 676 650 621 60036J4

327 178

$) 610AlO 3$

92S 980

102$ 1070 1157middot 1230 1300 137Smiddot

44middot4 soo 523 ssomiddot 540so6 46-5 432 368 274 18~8

J46 176 21-1 255 2802s_A 28 289 288 265 231 168

1-4-1 1-4middot2 1-4-3 1-4-4 1-4-5 1-4-6 1-4-7 1-J-8 1-4~9 1-4-10 1-4-11 1-4-12

10bull48 1231 13-S6 1397 1)821375 1))8 1303 1127 953 683) 51

048 067 o7A07 0 bull79 oa1 oss o bullao osa 0lt)0 096 099

J468 1740 1921 1978 1958 19$1 1911 lSSi162 1)98 1045

603

266 264 262 262 261 2512$7 2$6 24middot7 24-3 233 217

551 660 13middot3155 75-6 7~-97 middot4 72$ 67 51middotJ 44middot9 21middot1

475 605 A4220

875middot 910 970_

1000 1090bull 1166 1243 1330

5816

44middot444middot5 430 427 412 392 329 273 188 l0-7

117 101 204 22$ 2)7245 2562sa 257251 222 179

a-C))

Appendix Ct CALCULATED -DATA ( Ocntinued)

1-6middot1 1023 o$2 14-41 26S 505 41~6 26~

54middot5 13middot3l-6-2 1201 067 1boo 625 47-9 17shy~middot41-6bull3 1296 oA9 1 middot43 26 9 700 so5 20bull 4 l-6-4 l3j5 o 0 19~09 268 71bull3 A5o 514 222 1-6-5 1) 5 o81 19(gt4 271 725 51-5 238 l-66 1398 081 198) 27-0 736 8 S13 252~-middot l-6j 1405 083 199i 211 733 885 $middot06 2$9 l-6 13middot9~ 103 2amp 0 279 71 8 985~ 467 ~-69 1228 1 bull 02 17-SS 270 661 109$ 407 ~3~ l-6bull10 1025 100 lSll 26i 573 1175middot 27~S32middot~l-ampu 153 1-00 llft3 26 444 1270 22 24bull8 1bull6-12 294 100 52a 231 22 3 1360 95 172

1-9bull1 904 048 1275 2J4Z $28 S4$ 459 1$2 1-92 98$ oss 13-92 24middot4 57-0 6JO 49bull1 176 1-9middot3 1110 066 1$76 24middot9 63middot4 I2o 536 21-7 l--9-4 1187 072 1685 251 66$ 5 $$ bull 0 261 1middot9-5 llltJ7 1710 25middot4 67-3 93$ 536 28~20-671middot9-6 1186 o 8 1708 25-7 67) 980 $15 2691-9- 1161 oBo 1660 2$middot3 6$6 990 508 29-1 l~- ll-32 oB) 16sect0 2$8 632 1030 471 291 1-9bull9 109$ oa5 2$7 614 1075 29S~middot 0 4imiddot41-9-10 9~91 oas 262 S$1 1150~ 3 o 292 1-9-11 o9o u57 12JiO 21gt 26-77middot74

-45 26sect ~middot91-912 $69 091 sas 25 middot3 1)0$ 196 2J-8 1-9-1) 220 098 426 2)9 178 1390middot 84 16 6

0 0

Appendx C CALCULATED DATA (Continued)

Turbine Run Generator Generator lurbine Turbine Eft1e1eney Turbine lurbine Spee1f1c

Number Output Losses Outit Input Speed Output SPed middot k_-V KW R _ H_bull_P Percent r Thm HP rpm_ (9) tlo) 11) middot (12 _) (lJI ( ) (1$ (14)

2-9-1 9--46 055 1)62 258 528 580 164 2-9-2 1024 056 248 58 4 665 4 9 191iimiddot48 4~middot0 2-9-3 1132 067 05 2$0 641 795 52q 237 2-9-4 1148 065 1027 2$1 -~8 845 525 252 2-9-5 11 77 oso 16-83 253 6 910~ 522 270 2-9 6 1122 071 1600 251 622 960 47-5 2722-9-A 1092 015 1562 257 608 1010 445 2z12bull9- 1052 079 1514 261 580 1060 41middot7 2 2 2middot9-9 986 o82 ]429 26) 542 1105 372 277 2-9-10 915 086 1340 268 500 1160 334 27-6 2-9-11 638 087 972 254 )81 1270~ 229 250 2-9-12 )28 090 828 259 )19 1295 179 226 2-9-13 192 094 383 2$ 6 150 1370 7 3 152

-3 0

Page 23: The Effect of A Variable Draft Tube Flow Area on the

16

reduc ion at the wicket gatctsmiddot wae ade 1n the lfadraulioe middot

Laboratory of Oregon St middot te College in 1933 (20) Three

d1tterent thode ot reducins the tlow were t~ied

(l) Locking in the cloeed position pairs or wicket

gatea located opposite to eaeh o~er on the -periphery ot

the wheel

(2) Locking adjacent gates in an open position by

inserting blocks of wood between them and

()) Suocess1vely looking adjacent gates in the closed

position

The results indicated a arked reduction in both power

and efficiency when compared to the curves tor normal gate

operation However it was demonstrated that it was poae1bull

ble to ahitt the power and tfieiency curve ill relation to

turbine apeed lbis important feature will be diacussed

later

ihe main conclusion of the investigation was that conbull

trol by the conyent1onal wick t gates was auper1or to other

methode egtt control exercised at the gates the aelvebullbull

It would app$ar that the bebullt location tor flow conshy

trol would be in the draft tube since none of the objecbull

tiona prev1ously mentioned wou~d eziat there

As bas been stated previously the sole object or the

17

18

turbine is to produce power as etfic1ently as possible

The equation tor the power output of a turbine () Pbull 227)

PaWHe HP (4)55o bull bull Assuming the head 1a constant and a g te located in

the draft tube decreases bhe rate ot flow the power eu

only be increased if the etticiency increases

The ettective head Gn the turbine 1s conventionally

d r1ned as the difference between the auma ot the elevashy

tion head pressure head and velocity head at the entrance

to the turbine casing and the tailrace ($ Pbull 872)

lt ie recognized that the theoretical treatment ot

shock loss as given is highly approximate and serves only

to dictate certain trenda For example the area at xit

rom the wicket g tea CfUl be measuPed with some exactness

but there exists no guarantee that the wateP particles will

complet-ely fill the apace oz- will exit at the establiahed

g te angle The same can be said of the exit trom the

runner blades AssUIlptiona were implied which would indishy

cate that all water particles passing a given croea section

ampH traveling at the same velocity in the same direction

the e alone are autt1c1ent to show 11m1tationa in a theoretbull

1eal approach to the problem

Assume a turbine with ordinary wicket gates tor oonbull

trol compared gainst the same turbine with a gate in the

18

draft tttbe tor supplampment1ng control or the rate ot rlow

Let it also be assumed that the two turbines are opershy

ating at the same point It 1s desirable to predict relabull

tive performance of the two turbines 1 this point of

operation is such that edd7 s hook loss ot reasonable proshy

portions is present in the fir t turbine

~ tull erteot of the shock loss will be exper1 need

by- the fir t turbine

lhe second turbine will derive certain advantages 11

the gate in the draft tube is adjusted to reduce the tlov

1n the proper amount Since they vary a the square ot

the veloo1t7bull the lossabull in the aeroll case wiomiddotket gate

and runner passages will decx-ease aetet-r1ng to Figure 2 1

it can be seen that a decreased velocity v1 w-ill reduce the

eddy shock losa

The ent loss in the dJtaft tube of the second turbine

will be the sum ot the tr1ct1onal loss and the velocity

head at ex1t The velocity head dissipated will be greater

due to the closing action or the gate but the reduoed

t~ictional loss which ia a tunction ot the rate of tlow1

will partially balance this

It 1a entirely possible that the net reduction in

losses in the second turbine will lead to a greater ettibull

oiency and more power output than 4eYeloped by the first

turbine

19

In Figure 3 the plot ot power output against turbine

speed for Curv A~ represents the typical family of curvea

tor a reaction turbine Th b st sp ed is the locus ot

points connecting maximum eft1oiency at each gate opening

The operating speed is the coZUJtant turbine apeed which

passes through the point ot maximum efC1ciencr of the turbull

bine The plot of turbine efficiency against power output

for Curve A is also ahown

It the turbine with flow regulation in the dratt tube

oan demonstrate superior power and efficiency at part loads

the effect would be the same as a shifting or the power

curves toward the condition shown fop Curve B 11 Thisbull

illustrates th ultimate case of the uperpoait1on of best

and operating speeds It will be noted that the pet-form~

of the turbine ot Ourve Bu 1a better than that of CUrve

A at part loads because of ita ability to sustain a relabull

tively high etticienoy ovel a Wider range of power output

o Reguireaegts tort Test Velitication

It is desired to deterra1ne the effect on the turbine

performance b) the addition of a gate in the dratt tube

Th step in the teit will bet

(1 To determine the power output and efficiency ot

the turbine tor wicket gate settings above and below rated

conditione for a wide range ot speed

20

CURVEAbull

TURBINE SPSBD TURBID SPEKD

POIBR OOTPOl

Figure 3 - Turbine Performance Curves

21

22

(2 peat (l) with the gate installed in the drat

tube

(3) middot Converting middot all data to a constant head compare the

powere and effioiencies at the same wicket gate setting and

turbin speed tor the two cbullses

If the ddition or the gate indicates an improvement

in power output and efficiency and the powe~ curve shifts

to the right along the turbine apeed scale the advantage

ot draft tube con~ol of the flow will hav been demonshy

strated

Chapter IV

A E9J11pment

ih turbine used in this test is lJ 5 1nch Pelton

reaction turbine with a rated output ot 30 horsepower under

a head of 56 feet at a speed ot 720 reYolutiona per minute

Views of this turbine are hovn in Figures S and 6 The

turbine is installed on a concrete pad located over an open

channel in the Hydraulics Laboratory at Oregon State Colshy

lege The date of manufacture of this turbine was 1915

The water was delivered to the turbine from a sump

reservoir by two pumps operating 1n parallel Each pump 1a

an 8 inch Pelton double suction centrifugal pump witb a

rating of l$00 gallons per minute at a head ot 75 teet with

a speed ot 1175 revolutions per minute Tbe inlet tlange

ot tne turbine is $pprox1mately 18 feet above the center

line of the pump

A direct current generator was coupled to the turbine

to receive tne power d veloped as shown in Figures 4 and 7 The generator is a Spr gue Electrodynamometer rated at SS horsepower with a speed range of 7$0 to l$00 revolut1one

per minute The classification is type LO 26A 2)0 volta

Figure 5 - View of Test Turbine

Figure 6 ~ View of Test Turbine

and 149 amperes lbe generator ti ld was aepar tely

excited using direct current from a motor g n r tor ampt

(l$ p 4~8)

The power output of the generator waa dissipated in

the water rheostat (3 p 488-489) shown in Figures 9 and

10 The galvanized tank contain d water ot variable d pth

on an electrode ot cast iron m aauring 1bull x 1 x 1

In the initial installation of the turbine it was

intended that the power output should be measured with a

Prony brak bull For th purpoa68 or this teat it was decided

that the brake was too instable and the generator was

substituted The platform for raising the generator the

nee asary two teet for alignment was built out of available

material In this case heavy laminated wood blocks reiashy

torced with other timbers were used and bolted through the

concrete deck (11 Pbull 36-$7)

Due to the light concrete deck the lack ot mas in

the platform and the slight misalignment in the flexible

coupling ao e vibration waa encountered It seemed to

ncr aae linearly to a maximum at the speed of bout 750

revolutions per minute Above this speed no vibPation was

noticeable The vibration waa not se~ere and does not

appear to have materially affected the test results

26

B Intrumentat1on ~ eaeur1ng Devices

The pressure head at inlet to the turbine vaa meaave4

bymeane ot two )6 inch waterbullmeroury manometerbull connected

in series as shown in Figure 8

The terminal voltage ot the generator vas meaeured by

a laboratory voltDleter with a range to )00 yolta and callbull

brated to within 15 Yolta

The armature current bull and hence the line current was

measured by a laboratory ammeter with a range to 150 amperea

and callbrated to w1 thin o 7S amperes

Tae rate ot tlow was established by weight and time

meaeurementa The weighing ank has a capacity ot 121 000

poundsJ the weight belng indicated by Toledo direct reading

scales Timing was done with a hand atop watch with clivibull

aion ot 02 second

he ~ater level in the tailrace was dete~1ned by a

hook gauge lhie was read to the nearest 001 toot

The turbine and generator speeds were eaaured by a

hand tachometer The technique of almost cont1nuoua readbull

ings of the speed gave an error ot no more than 5 revolubull

tiona per minute

c Operational Procedure

Atter the water level in the aump was checked to

insure an adequate auppl7 the puapa were primed and

27

Figure 7 - Test Generator and Plattorm

Figure middot8- Instrument Board and Field Rheostat

28

started After venting they were valved for operation 1n

parallel

The motor generator set was started to supply the

field current and the circuit breaker was closed Water

wa added to the water rheostat to the level shown in

Figure 10 ~ field current wae minimized by cutting in

all the f ield resistance in the field rheostat of Figure 8

The l2 inch gate valve shown in Figures 5 and 6 waa

slowly opened and the turbine and generator brought up to

speed The 12 inch gat valve and turbine were vented and

the pumps were checked to insure neither had lost ita prime

lhe water rheostat offers very steady load 1f the

water level is essentially constant and the water temperabull

ture 1a fixed () p 488~89) In order to maintain this

constant temperature it was decided not to circulate the

water in the rheostat but rather to allow the water to

boil thua achieving the desired result A standing wave

was set up on the face ot the electrode by the boiling

action but a atable load was eatablished except at very

low water leYels where th11 agitation led to fluctuationa

in the line current

After putting the turbine and generator on the line

maximum power was dissipated in the rheostat by redueing

the turbine speed to between oSO and Soo revolutions per

minute Salt vas added to the rheoetat wat r to increasemiddot

29

Figure 9 - View of Water Rheostat

Figure 10 - View of Water Rheostat

Separate Field ExcitationFrom Motor-Generator set Compound Water-Mercury

---shy

re Manometer

I Q)

~ 0

~

Book Gauge

Open Channel

I

Slap Reservoir

Figure 11 - Wat~r Flow Diagram and Electrical Layout

31

waiting pe~iod ot perhaps an h~ followed

while the boiling point or the water wbulls reacbe4 During

this ti+ne the manometer was vented end eheoked electrical

measur1ng 1nstlUments were connected end the hook gauge was

adjusted tor elevation

It required about two- houtte tor the generator to reach

its normal operating tempe-ratu~e_ After the water in the

rheostat and generator had reached their operating temperabull

turea it was possible to begin the taking of data

The only vaPiable which was controlled wee the turbineshy

generator speed However the upper l1ut1t of safe line

current was slightly over 100 ampJilPampPes and the eireuit

breaker would open when the current reached lOS ~ere bull

Control was exercised by means ot regulating the water

level and salt 1n the water rheo tat and the res1stsnoe of

the tield rheost t~

The etfeet ot each type ot regulation on the three

variables is shown below

Volta Aaperebull Speed

Inc Dec Inc Dee~ Inc Dec

Wa~e1 Level Inc Dec~ X

X X X X

X

Salt Concentration

Inc Dec X

X X X X

X

field Resistance

Inc Dec

X X

X X

X X

32

Jlot all methods gave the ame amount ot change in a

given variable and a period of experiment and trial led to

the following scheme starting the rune with the lowest

turbine speed the water level was high with a high amount

ot salt and the field resistance was cut completely out

Aa it became necessary to increase the speed tor each

aucceasive run either cutting in t he field resistance

decreasing the salt concentration or lowering the Vater

level would produce the desired result However decreasbull

1ng the salt concentration had to be done Without a net

gain in water which led to a tluahing procedure that was

not particularly good because cold water was introduced

which required time to heat to the boiling point Cutting

1n additional field resistance was a good method but th1a

increased the amperage possibly to the point of opening

the circuit breaker Lowering the water level was aatiashy

factol1 until the level got too low causing the current

fluctuation previously mentioned Actually it turned out

that a combination of lowering the water level and cutting

field resistance in would carry the speed from ita minimum

to 1ts maximum value it the proper choice were made each

time the speed waa to be changed At the conclusion of

each aet of runs at a high speed the water level would be

low and the field resistance high

33

TURBINE

PAD AND DECK

TAILRACE

WATER SURFACamp

CONCRETE

DRAFT TU1B INSERTS

7 5( DRAFr TUBE

FLltJI ARIA

5~ DRAFT TUBE

FLOI ARSA

Figure 12 - Sketch of Draft Tube and Test Inserts

34

Figure 13 - View of Draft Tube Insert

Figure 14 - View of Draft Tube Insert

D c __ ~s_middot hedu_le of

A number was assigned to each run The fi~st number

applies to the draft tube tlow areas

1 bull 100~ flow area or 0~ oonatriction

2 - 7S tlow area or 2$ conatr1ct1on

3 SoC flow area or so~ constriction

The second number refers to the wicket gate openings

9 over gate opening

6 bull intermediate gate opening

4 bull one h lt gate opening

The third number 14entif1ea the location of the particular

1Wl in a set ot rona made at a given dratt tube tlow area

and wicket gate opening

fnua run number 1bull4bull10 would identity this as the

tenth run ot a set made at halt gate with 75 ot the draft

tube t1ow area

Rune w re made tor a g1yen dratt tube condition

Firat tor tull 41-aft tube flow area seta ot rune were

made for the overgate halt gate and intermediate gate

conditione An insert was placed in t he draft tube and

rune based on the same gate conditions were made tor the

7S~ draft tube flow area case The insert was then changed

to allow only $~ draft tube flow area

The inserts are sketched 1n Figure 12 and photographed

ln Flgurea 13 and 14 They oonaisted of circula~ segments

36

or l2 ineh plywood mount 4 on wooden legs 10 inches high

The 1nse7te were placed in position and secured by th use

ot a-clamps on the legs and the outside ot the bottom of

the draft tube The obvious disadvantage to this method

waa the neoeasity tor draining the water from the tailrace

tor a change ot 1naert The advantage vas of course the

simplicity ot design and construction

Chapter V

DATA-A Original Data

The normal data-taking crew consisted or two men

Assuming adjustments having been made to secure a certain

turbine speed (aee section on Operational Procedure) one

man would take semi-continuous speed readings with the hand

tachometer until a state or rotational equilibrium was

reached This could be only a period or two minutes up to

ten or tifteen minutes As soon as steady speed was

assured the data taking would begin The second man went

to the weighing tank Where a minimum ot three weighingamp

were made The requirement was to get three consecutive

readings such that the ditterence between tbe smallest and

largest time did not exceed 04 seconds The time to

collect a given weight ot water was then assumed to be the

arithmetic average of the three times He then went to the

hook gauge determined the hook elevation and then

recorded the data on the data sheets The first man meanshy

while had taken readings of the line voltage line current

and manometers and checked the turbine speed by multiple

readings During the length of the run all values were

38

checked to determine mean values for recording

The minimum length of one run was about five minutes

If one or more measure ants tended to drift during the run

all values wer discarded and a new run began as soon aa

qu111br1um was stabl1shedo

B -0-al_e_u_l_a_t--d Data

The h d on the tu~bine 1 defined by

($)

The maxtmwm velocity V4 was equal to about o8 tampet per

secon4 which makes it a negligible quantity when converted

into velocity head

An engineerbulla level was used to deterine the d1ffePshy

ence 1n elevation between the compound water-mercury manoshy

meter and the hook gauge Using this value the equation

for turbine bead becomes

where z4 is the hook gauge reading

The rate of flow 1 cent

w weight or water collected average time to collect

The inlet velocity v1 vas calculated by dividing the

weight rate or flow by the specific weight of water and the

)9

area ot ~e inlet pipe This was equivalent to dividing

the weight rate of flow by 490 Then the power input to the turbine is equal to

WHpin rri

10 (6)

Also

(P ~ut) Turbine

(P out) + Generator

(P lost) Generator

The power output of the generator is simplJ the

produot ot the terminal voltage and the armature (line)

curPent The power lost in the generator can be subdivided

into copper losses and stray power losses lo evaluate

these cunes based on losses of an identical generator

11leampsured by the Department ot Mechanical Engineering were

used The loss curves are reppoduced in part in Figures

15 and 16

Determination ot generator losses proceeds as tollowau

(1) From Figure 15 detem1ne the vo1tage drop in the

armature circuit using the temperatures of 1220 F and the

meaaured current

(2) The induced voltage is t~e sum of the terminal

voltage and the voltage drop 1n the armature circuit

() Entering the induced voltage and the turbine speed

into Figure 16 the stray power loss can be determined

(4) The copper lose can be evaluated from Figure 1$

using the measured current and the temperatlll-e of 1220 P

40

25 ~------~--------~--------~------~

U) -U) - 20

f-4 ~

-~ -gt 0

0

VOLTAGE DROP

~ - i -

- bullbullbull bull - -middot-middot -+ ~- + -t--+ ~ - ~ middotbull ~-~ middott- -+----- _ -4 middotmiddot- --~-+-t---r~~ ~--+t-t- - ---t-c-++~-ulf--

0 50 75 100

Figure 15 - Curves of Generator Voltage Drop and Copper Loss

41

1200

1000

800

600

800

0

0

~-

middot--~ 1shy --1 + bull l

100

I -

150 200

IIDOOED VOLTAGB (VOLTS)

Figure 16 - Curves of Generator Stray Power Loss

_ j

-bullshy -L---- shy middot -shy

250

- r

42

(5) The generator los os equal the sum of the eopp r

loss and stray power loss

~e efficiency or the turbine is taken as

etticiency u e =P out (8)Pin

~ample pound Determ1n1gg turbine Power Output

The following data are taken trom that ot Run 1-9-1

Line voltage 1040 volts Line current 870 amperesSpeed 355 revolutions per minute

The induced voltage 1a determined as follows

Line voltage 1040

Voltage drop 90 using Figure 15 with line current of 870 amperes and temperature ot 122 degrees)

Induced Toltage 1130 volta

The power output of the turbine is determined as follows

Generator output 90$0 (line voltage z line current)

Oopper loss 7 (using Figure 15 with line current of 870 amperes and temperatUe or 122 degrees)

Stray power lose 470 (using Figure 16 with speed ot 355 revolutions per miDUte and induced voltage or 1130 volts)

Turbine power output 9527 vatta

or turbine power output 1s 12z2 horsepower

43

The conversion of the calculated data to a constant

head is based on the conventional assumption of constant

efficiency regardless of turbine head For a constant head

ot 81 teet a purely arbitrary figure the tollowing relashy

tionships are ass1lJiled to be true

I ____L (9) (i)l72

(10)

For these two values the specific a peed may be combull

putedt

N t Jt VPt (11)8 243

Chapter VI

~RESULTS

A -Pr_e_ae_n_t_a_t_t_o~n g Reaultbull

Graphical presentation ot the results ot this te1t

are given as follows

Figure 17 -Turbine characteristics with 100~ dratt

tuba 1low area

Figure 18 - Turbine characteristics with 7S dratt

tube tlow area

Figure 19 bull Comparison ot power and etticiency at

over gate conditions between 100 and

75~ draft tube flow area

Figure 20 bull COZQparison of power and ettic1ency at

halt gate conditions between 100~ and

7S~ draft tube flow area

Figure 21 bull Comparison of power and etticiency at

over gate condition between 100~ and

So dratt tube tlow area

Figure 22 - Comparison in variation ot apec1t1c

speed between 100 and 75~ dratt tube

tlow area

50

45

20

-bull - 1--shy40

bull J-~ 30

~ ex

~ 20

~~ ~ -)q

I

~ - _

- -

10~ OF DRAFT TUBE FL(Jif AREA

CONSTANT HEAD OF 8l FEST10

POIER OUTPUT EFFICIENCY SPECIFIC SPEED

0 ~--------------_--------~------~------~ 400 600 800 1000 1200 1400

TURBINE SPEED (RPM)

Figure 17 - Turbine Char~cteristics with 100 Draft Tube Flow Area

50

46

-bulllle

~ 7 ~ OF DRAFt TUBE FLOW AREA

0 -~~-rl C05STAMT BEAD OF 81 mET 1J~

POIER OOTPUT ---+- ---o ~_H EFFICIDCY ~ I shy

bull ql SPECIFIC SPEKD - ~ -

bull ~ J 10 L rmiddotr- r- -

bullz- I

~~ 30 ~~--~----~~-

20 ~ ~ middot-shy

26

~~ 25

~0 ~r-----i (

Tbull -bullshy

400 600 800 1000 1200 1400

TURBINE SPEED (R PK )

Figure 18 -Turbine Characteristics with 75 Draft Tube Flow Area

47

EFFICIENCY 60

1-----shy

-~ 50~--~--~~-~middot middot middot middot r~-~----~~~~---4~-r~-~~gtt

II

POWER~ J ~ bull bull

u I

sH

40~------+-------+---- -~~--~~-~~~~

~----~rl 1 bull

I

I

0~--------------~------_------~--------

~ -OVER GATE CONDITION

COIJSTANT HEAD OF 81 FEET

0 o 10~ DRAFt TUBE

_-- _ 7~ DRAFT TUBamp FLON AREA II

10_~-----+--------r-------r----~~

400 600 800 1000 1200 1400

TURBINE SPEED (RPM)

Figure 19 middot - Comparison between 75 and 100 Draft Tube Flow Areas of Power and Efficiency at Over Gate Conshydition

48

t

bull --4 r ~- ~ middot~

70 1-----------+-~~~~~+middot ~ ~~ middot middot -~~--~~--------~~----~-+1

-~-

Atbull bull

lla-

60

amp0

40

20

10

oampOO

t _ - - ~-+- - -~-

l2 GATB COJIDITIOJJ

COJISTABT HJW) OF 81 JBET

o 0 lOQ( DRAFl TUB8 FLOI AREA

e-- - e 75 DRAFT TUBE FLOW AREA

800 1000

- r-

~

TURBIbull SPBIID (RPII)

Figure 20 - Comparison between 75 and 100 Draft Tube Flow Areas of Power and Efficiency at Half Gate Conshydition

49

60

50

-40

bull 30

IIQbull

20

10

0

400

- t - ~

EFFICIENCY

_J bull - bull bull

~ r r middot t -+ shy L -t -

OVER GAD COliDITIOI

CONSTABT BEAD OF 8l FBB

o o 10~ DRAFt TUBE FLOI ADA middot--- 5~ DRAF TUBE FLQPi AREA

600 800 1000 1200

Figure 21 -Comparison between 50~ and 100~ Draft Tube Flow Areas of Power and Efficiency at Ove~ Gate Conshydition

50

25

20

15

10

0

Figure 22

~- T -4 -t- -l --~-

t-~ I

middot --~- t ~---- _ __ _ + --

----~- --r-- --

~-=J-~-=-~ -==~ _ ~- -- ---f---1 - shy

CONSTANT HEAD OF 81 FEBT

o--o 1~ DRAFT TUBE FLltll AREA

75C DRMT TUBK FLCIJ AREAmiddot--middot-middot 600 800 1000

TURBINE SPEED (RPK)

Comparison of Specific Speeds for 75 and 100 Draft Tube Flow Areas

51

B Discussion 2 Result

Consideration of Figures 17 and 18 indicates the

overall eftioi ncy pattern or hill is significantly or

rounded for the 7$~ flow area than for the 100~ flow area

bia implies a greateP efficiency is possible at speeds

leas than or greater than design speed with an insert in

the draft tube However the muilDum efficiency is lemiddotas

Direct comparison at over gate conditions is made in

Figure 19 ~e same general trend is noted tor both the

etticiency and power curves for the 7$~ flow area case

The eurves show higher values at overspeed than do the

correaponding cWvea for the 100 flow area case It ia

not clear whether the curves have been shifted by the dratt

tube constriction or whether the curves simply bulge past

the normal curves at both overspeed and underspeed condishy

tions The power curves apparently peak near the aeme

point bullalthough maximum power is still obtained with the

normal draft tube area

For the comparison at halt gate operation shown in

Figure 20 a general improvement has apparently been made

by restriction of the draft tube flow area At every speed

the etticienoy and the power is greater for the restricted

tlow case The two ett1o1ency curves and two power curvea

are practically parallel throughout the speed range ot

teat

As the flou aroa i e decreased still farther a s1gn1

ticant change appears Reterr1ng to Figllle 211 tor the $0

flow area curves it a obvious that exit losses have

become excessive at the overgate condition because the

efficiency and power are everywhere leas than tor the case

of normal draf t tube area

Earlier it was pointed out t hat 1t the r esult s 1nd1bull

eated an increase in both power and ef tieiency- t hen it

could be assumed tha t the additional los s i ntroduced with

the draft tube insert is less than the diminished losses

due to leas shock losa and water passage losses For the

places where both the efficiency and power have been

increased we can assume that the insert has improved turshy

bine performance

For the places where the power haa been decreased

nothing can be said as to the elimination of ampbock loss

because the new lose present with the drat tube insert has

overshadowed any gains in eftecti Ve head upatJ-eam of the

insert

Near the peak of the efficiency hill howeve~ it may

be pointed out t hat shock loaa ie a minimum with a normal

draft tube and the insert merely adds an additional loss

with the resultant decrease in maximum efficiency tor the

7$~ flow area case

Perhaps the most s1gn1ticant set of eurves is shown aa

53

Figure 22 In this graph values of specific speed tor the

75 and 100~ flow area cases for both over gate and one

halt gate openings are plotted against turbine speed At

every speed and both gate openings the value ot specific

speed for th 75~ flow area case is greater than that for

the 100 t1ow area ease

Since the head is a constant for both situations this

may be interpreted in either of two ways trom equation

(11)

(1) For the same turbine apeed restriction of the

draft tube t1ow area resulted in greater turbine power

(2) For the same power amputput the turbine with 75~

draft tube flow area operated at a greater speed than did

the one with 100 flow area

Since the required diameter of a turbine varies

inversely with the speed the second interpretation could

be stated such that a smaller turbine could be used to

develop the same power output

Whether viewed trom the aspect of increased power

greater speed or reduced size the performance of the turshy

bine with reduced draft tube flow area is superior to that

with the nolmal flow are in the draft tube

The curve of specmiddotific speed versus turbine speed for

the so draft tube flow area case at over gate cond1t1ona

was not included in Figure 22 This curve lies below that

for the 100~ flow area c se at all speeds

In elaboration ot the second interpretation of Figure

22 attention is directed to the relative magnitudes ot

increased apee1f1c speed tor the two gate openings Assumbull

ing that the increase in specific speed implies a shift ot

the power curve to the right along the turbine speed scale

the power curve would be shifted more tor tbe halt gate

opening than tor the over gate opening

It thia trend could be extrapolated to the other gate

openings the tendency can be seen tor the line ot beat

speed to rotate toward the line of the operating speed as

illustrated in FigtU-e ) The advantage of this has already

been discussed

This particular turbine has a low specific speed tor a

reaction turbine Aa the rated value of apecitic apeed tor

reaction turbines increases the line ot beat speed departs

even more radically from the line of operating bullpeed It a

test similar to this were conducted on a reaction turbine

ot gleater specific speed it is pJobable t hat the rotation

ot the line of beat apeed would become more p~onounced

The scheme used in th1a teat had two obvious dr wbull

backs The first was the decision to leave all the wicket

gamiddottes installed tor all conditions ot the draft tube

These gates predominated in control of the tlow The

inserts added to the draft tube merely acted as auxiliary

55

contrGla

The aecond drawback was the choice or device to place

in the draft tube The reasons foll selection of this type

of device have been previously mentioned It is to be

anticipated that adaptation ot dratt tube flow control

would result 1n a better device for an actual turbine

installation Such apparatus might take the form of a

pneumatic bladder or a h7drau11oally operated variable

venturi section in the draft tube It is conceivable that

the gate as used in this test might be adapted also

Chapter VII

OONCLtJSIOfS

From the results of this test the following eonolubull

e1ona aa to the effect ot a variable draft tube flow area

on the performance or a r action turbine may be drawn

(1) The effect ot a variable draft tube tlow area 1a

generally favorable upon the operat1Gn ot a reaction turbull

bine because or the tendency tor the line or beat speed to

rotate toward the line ot operation This resulte in

better performance of the turbine at partbullloads

(2) he etf1o1ency eh111 tor the turbine beeomaa JDore

tlat at the top leading to a smaller max1JilWD effic1enc7

but e reater etticieney at other pointe of operation with

the insertion ot an auxiliary control ror the rate ot tlov

in the draft tube

(3) The power output of the turbine will increase at

over speed over gate conditione as well a at part gate

conditions with the proper amount or draft tube eonatr1cbull

tion or flow

(4) It is possible to eliminate at least partially

eddy type shock loss by tho introduction ot flow control

in the draft tube

BIBLIOGRAPBl

1 Addison Herbert A treatise on applied h-draul1cs New York Wiley 1954 724 Pbull

2 Allen o M and I A Winter middot Co111parative testa on experimental draft tubes Tranaact1ons ot the American ociety ot Civil Engineers 87t893bull970 1924

3 Barrows a E Water power engineering 3d ed ew York McGraw-Bill 1943 791 Pbull

Bovet G A Modern trenda in hydraulic turbine design4middot in Europe Tranaactions of the American Society ot Mechanical Engineera 75975bull993 1953bull

s Oreager William P and Joel D Justin Hydroelectrichandbook 2d ed New York Wiley 19$0 1151 Pbull

6 Daily Jamea w Hydraulic machinery Int Hunter Rouses Engineering hydraulics Hew York Wiley 19$0 p 8$8bull99

Daughertybull Robert L Bydraulie turbines ew Yorkbull7middot MoGrav-Hlll 1920 281 Pbull

8 Daugherty Robert L Inveat1gat1on of tne performance ot a reaction turbine ~anaactiona or the American Society ot Civil Engineers 7811270bull1304 1915

9 Davie L M Model and prototype testa Int Trend in hydraulle turbine practice symposium lranaactions ot the American Society ot Civil Engineers 1o63S3middot368 1941

lfJ Doland James J Hydro power engineering Hew Yorkbull Ronald 1954 209 Pbull

11 Gandy Theodore s and Elmer c Schacht Direct curshyrent motor and generator troubles operation and repair New York McGraw-Bill 1911 293 Pbull

12 Gibaon Arnold H Hydraulics and ita applications5th ed London Constable 1952 813 Pbull

58

13 Button s P Component loases in Kaplan turbinebull and The prediction of efficiency from model tests Probull coedings of the Institution or Mechanical Engineers168743-762 1954

14 Knapp R T~ Oavit t1on mechanics and its relation to the d sign or hydraulic equip ent Proceedings or tne Institution ot Mechanical Engineers 166150bull16) 1952

15 Langsdorf Alexander s Principles of direct curHnt mach1nee 5th ed New York r~cGrawbullH1ll 1940 746 Pbull

16 Lsrner Chester w Characteristica of modern hydraubull lie turbines Trans e~ions of the ~~erican Society ot Civil Engineers 66306-386 1910

17 Linsley Ray K Jr and Jobulleph B Franzin1 Eleshyments of hydraulic enginebullring New York McGrawshyBill 19$5 $82 Pbull

18 Mead Daniel w Hydraulic machinery llev York McGraw-Hill 1933 396 Pbull

19 ead Daniel w Water power engineering New York McGrawbullRill 191S 843 Pbull

20 Mockmore Charles A Part gate operation at water turbines Corvallis Oregon State College Department ot Civil Engineering 1933 11 numb leaves (Unpubshylshed typescript)

21 Mockmore Oharles A Flow characteristics in elbow dratt tubes Transactions of the Amez-ican Society ot Civil Engineers 103402middot464bull 1938

22 Moody L F Hydraulic machinery In c v Davis Handbook ot applied hydraulics New York McGrawshyHlll 1942 1082 Pbull

2) Ptau At-nold Hydrbullulie turbine handbook ld ed Milwaukee AllisbullOhalmers ManufactUIing Company 1948 70 Pbull

RheingalUI w J Recent developments in Francis turshybines Mechanical Engineering 74189-196 1952

25 Russell George E Hydraulica 5th ed New York Henry Holt 1942 466 Pbull

26 Safford A and E P- Hamilton American mixed tlow turbine and ita setting Tranampactions or the Amerieal Society of Civil Engineers 851237bull1)56 1922

27 bull Spannhake W1lhe1Dh Problems or modern pump and tur b1ne design Transactions of the American Society of Mechanical Engineers 56e22$-248 1934bull

28 Sutherlandraquo R A Better ethod or representing and middot tudying water turbine performance ~ansaetions ot thmiddote American Society of Mechanical Engineers 68t675bull 686 1946

29 Teats ot five models or draft tubes tor turbines Engineering News-Record Pbull 182-184 Aug 2 1923

30 White w M American hydztaulic turbines Mechanical Engineering S2t390bull39S 1930bull

31 White w M lhe hydraucGne rega1ner1 its developmentand appl1eat1ons 1n hydroelectric plants Meohanlobulll Engineering 43t37Sbull380 1921 middot

32 Winter I A Economic principlebull in designbull Int Trend in hydraulic urbin practice bull a ampoeiumTranaaot1ona ot the American Society ot Civil Engineerslo6332bull3S2 1941

33 Wiel1cenua G F Fluid mechan1ca or turbo-machineryNev York McGraw-Hill 1947 613 Pbull

APPENDICES

c

Appendix A

NOATIOB

A Angle between the absolute velocity vector and the tangent to the rwmer Subscripts 1 and 2 refel to entrance and exit ot the runner blade

B Angle between the relative 1elooity vector and the tangent to the rwmer Subscripta 1 and 2 refer to entrance and ezit or the runner blade

Angle between the tangent to the runner blade tip and the tangent to the runnel- Subscripts 1 and 2 reter to entrance and exit of the rt1rmer bladebull

Blade angle-gate opening conetant defined by equation (1)

e 09erall efficiency

g Gravitational acceleration assumed constant at 322 teet per second per second bull

H Turbine head detined by equation ($)

m Exit loss coeft1e1ent

Turbine speed expressed in revolutions per minute

Turbine speed under a constant head of 81 teet

specitic apeed of the turbine under a constant head ot 81 teet

p Power output in horsepower ot the tvbine

Power output of the turbine Ulder a constant head ot Sl teet

Pl- Pressure head at entrance to the tUlb1new

l1 Peripheral velocity ot the runneP Subacr1pta 1 and 2 refer to entrance and exit ot the JUnllampr blade

62

v Relative velocity reaulting trom the combination ot the absolute water velocity V and the runner periphshyeral velocity u Subscripts 1 and 2 refer to entrance and exit ot the runner blade

v] Relative velocity vector necessary to produce a tanbull gential entry into the runner blades

V Absolute water velocity Subscripts l and 2 refer to entrano and exit ot the runner blade

v2 Velocity head Subscripts 1 and 4 reter to the ~8 entrance to the turbine and the tail~ace wate~

w Unit weight ot water assumed constant at 624 pounda per cubic toot

V Weight rate ot flow in pounds per aeooncl

XX Velocity component ot ahook See Figule 2

Z Elevation head Subscripts 1 and 4 reter to entrance to the turbine and the taibace water surfacebull

Appendix B ORIGINAL DATA-Run

lfwnber

0-4-1 0-4-2 0-4-3 o-4-4 o-4-S o-4-6 0-4-7 0-4-8 0-4-9o-4-lo o-4-11 o-4-12 0-4-13

o-6-1 o-6-2 06-3 o-6-4o-6middotS o-6-6 o-6-7 o-6-8 0-6-9 o--6-lo o-6-11

Speed

rmiddot2middotbullmiddot(1)

336 38$ 451 S$9 620 669 6lt)$ 120 787 860 932

102imiddot109 bull

352 355 443middot 543middot 620 654AJs32

911 1001 1111

~essure Head rt (2)

410 410 416 426 431 43-7 439 44-9 452 467 482 soo $1 bull $

350 351 35middot7 )66 37-9 37-9 392 41 bull 3 43middot3 460 489

Elevation Bead

fjj $7 $7 $7 $7 $7 $7 51 57 5-15858 $8 58 56 56 $6565656 51 575As5a

Velocit Head

flj 07 07 07 06 06 06 06 os 05 os0404 03

09 09 oa o8 o8 os 07 07 06 o~o

Total Head rt ($)

47middot4 4A44 o 489 49-4 soo $02 $11 $14 $29 5imiddot45 2 576

41 bull $ 416 421 430 44middot3 44middot3 456 47-7 496 523551

Plow

lbtjec

326 324middot317 311 306 30029middot28 middotmiddot middot 386 275middot260 240 218

359 36~35 bull 349 345middot 339 330 318 300 273 240

Line Potential

vyqjbull 1060 1220 ~-0o 1920 2150 2000 2$60 2000 1940 18)015io11 o

1000 1100 139bull5 1760 1925 16$0 1620 1610 1540 1330 870

Line Current

amlscs 960 900 830 740 730655 70bull 0 530 660 600 5imiddot54 6 )60

982 930 860 780 ~3-545

79-5 74-5 670 560 370

P

Appendix B ORIGINAL DATA (Continued)

Run Number

Speed

Pbulltmiddotbullmiddot )

leasure Head ft(2

Elevation Head tt(J)

Velocity He-dfmiddotj

Total Bead tt($

Flow

lbstsec( )

Line Potential vo~ta( )

Line Current

amjs (sect

0bulllt)-1 0-9-2

3ll6 398

28o ~~1

$6 56

1o 10

346 347

390 365

1ooo 1190

aao 835

0-9-3 0-9-4 o-9-S

472 565 632

292 305 312

$6 s6 56

10 o9 o9

)$8 J7~o 37~7

381376 37o

1)6614oo 141o

820 ass ass o-9-6 0-9-7 0-9-8 o-9-9 0middot9-10

680 120 762 844 920

)24337346 366 390

56 $6 56 57 $7

09 os o8 oa 07

)89401 410 431454

367~ 357348 34o 322

1400 1J6o l36o 1310 1170

843 820 7957So 67~0

0-9-ll 0-912

1001 1100

41 bull 7 45-3

s 7 6~0

06 os 480 $18

299 268

980 65$

560 36~5

1-4-1 1-4-21-4-l1-4shy1-4-5 1-4-6 l-4-7 1 4-8 1-4-9 1-4-10 1middot4-ll 1-4bull12

354middot452 562 62q 674shy102 752 760- 863 932

1022 1100-

)82389 4014oa 416 41--7 423 428 44-2 45-7 486 49-2

51S757 51 5-7 5middot15zs sa $8 58 59

07 07 06 06 06 06 06 os o bull o 04 o J

446 45-)46middot4 471 ti7-9480 q86 491505 $19 548 55-4

)28 320 311 306 300 295 291 286 269 2582iimiddot21 bull

1080 14Lo 1550 153-5 1470 141-0 1385 1310 1310 1230 1120 855

970855 875 91-0 94~0 975 966 995 860 77-S 610 4fo

0 ~

Appendix B ORIGINAL DATA (Contirmed)-Run Speed Pressure Elevation Velocity Total Flow Line Line

Number Head Head Head had Potential Current rtjjmbull t~ bttec vyfs am~a12) ( ) ti fli 8

1-6-l $6 33$ $6 0bull9 400 364 1100 93 0 1-6-2 41 34laquo2 $6 oa 406 JS7middot iios a5s l-6-3 500 3~0 5bull6 os 356 1 1 o aos 41middot~1-6~4 35bull4 5-6 oa 41middot 352 16~0 82 0 5~1-6-5 5 bull 36_2 Sbull6 08 42bull6 349middot 161 ~ 0 86~0 1-6-6 622 366 $6 oe 43bull0 345middot 158 0 88~$ 16-A 649bull 37bull1 56 os 43-S 342middot 1570 895 1~- 386 57 07 46-0 192 ) 125A44 333middot 1-6-9 3) 404 5middot1 07 468 317 1620 675 1610 911 42-4 5-7 o6 48-7 298 168 0 61 0 1-6-11 999 451 56 os Sl ll 276 ~2-0 530 1-612 1115 485 58 04 54middot7 238 90 )3 0

1middot9-l 355 279 56 10 )45 385 1040 870 1-9-2 399 28J $6 10 )49 38$ 1140 86 5 l-9-3 ~ ao 291 56 ~0 35middot1 J8J_ JJ6o 815 1bull9-4 579 303 56 09 )68 375middot J4JO 830 l-9bullS 40- 313 )6 09 31middot8 370- 1460 82~0 1-9bull6 679 2) 56 09 3 bull8 364middot 1670 710 l-9-7 682 319 56 o9 384 ) 62 1460 79 5 l-9-8 724 33middot5 56 o8 399 3$6 bull 1480 76 -5 1-9-9 762 34middot3 $6 0 bull 8 407 )48 14910 13middotS 1-9-10 833middot )60 5middot7 os 42$ 339 144$ 686 1-9-ll 926 39middot1 5-7 07 455 318 1290 600 1-9-12 1000 41middot3 0-6 476 298 1115 510$ ~ 1middot9-13 1105 452 s o4 $14 2$6 710 )10

~

Appendix Bt ORIGDIAL J (Continued)

Run Speed Pressure Elevation Velocity Total Plow Line Line Number Head ltead Head jlamp$d P()ten~ibulll Current

r~~~m ft ft lbs~seo voltattj rgj twimiddot t 1 t2gt lt3 ou t ( rt

2-9-1 384 289 S 6 10 35 5 1400 1170 810 2-9-2 443middot 29$ $6 ltimiddot9 360 379middot 11(0 87$ 2-9-J 536 30bull 3 sc 09 )68 374middot 1)40 84 bull) 2-9-4 571 306 $6 09 3~1 372 120bull 0 955 2-9-5 623 316 S6 09 J l )6S UJSo 77$ 2bull9-6 669 327 S6 09 )92 )61 1240 905 2-9bull7 712 )39 56 os 40-3 351 12(0 86 bull0 2-9-8 ~5$~ J48 56 oa 412 348 1290 81 bull ) 2-9-9 04 )63 56 oa 42-7 339 12ltJO 76$ 2middotmiddot9-10 8$2 376 5middot1 07 440 33~- ~ o 710 2-9-11 955 394 5-1 o6 457 300 1100 506 2middot9-12 1000 421 $7 06 48middoti 295 1020 $18 2-9bull13 110~ 463 56 05 $2 267 620 3~0

oshy0

Appendix Gt CALCULATED DAgA

Turbine Run Generator Generator Turbine Turbine Efficiency Turbine Turbine Specit1c

Number OutputKWlt21

Loa~Jes KWlol

Outut K bull (H)

Input RP 12)

middot Percentlt13gt

Speed r~Jmiddot(

0ltput HP ~1

Speed r-m

( 6) middot

o-4-1 0middot4-2 0-4-3 0-4-4 0-4-5 0-4-6 O-qmiddot7o-4-8o-4-9 0-4bull10 0-4-11 o-4-12

1018 1o9a 1220 1)62J40214oa1J4oo 1357 1320 1164 997 718

046 o59 071 092 096 1071oo 134 104 100 109 107

14261sso 17)01948 2008 20322011 1999 19 09 1708 14-84 11o6

281279 27-7 276 215 273271 268 268 26h 258 24-5

soa 555 62$ 705 7)1145 742 74-6714645 51s 45-1

440 sos 585 720 195 sso sao 9$$ 985

1065 1135middot 1230

318 357 319 416 422 419412 39middot9 378 324 260 191

102 12bull4 148 191 21bull 3 22o 233 249 24924middot9 238 221

0-4middot13 418 104 699 228 306 1300 117 18)

o-6-1 982 045 1376 271 $08 496 376 124 o-6-2 o-6-3 G-6-4o-6-5 0-6-6

1023 1200 13 73 J415 139h

051 0middot66 oaa ()bull 96 088

14-39 1696 1958 2026 1986

276 27middot4 273 278 274

$20 61 8 717 7)0726

q95615745 8)5685

390 ll5middot3 sos soo 490

127 170 218 243 2$$

o-6-7 o-6-8 o-6-9o-6-lo

1288 1199 1032 7-45

o9o 094 09$ 096

1846 1733 1511 1128

274 276 271 260

67S 629559 43middot4

980 1085 1165 1245shy

436 )83316 21bull 7

266 276 270 239

0-6-11 322 1oo 566 2141 2JS 1350 101 177 0 --4

Appendix C CALCULATED DAlA ( Continued)-Run

Number Generator Generator

Out2ut Losaes xw LW- 12gt (lO)

Turbine Out2ut

ltPlJ

Turbine Inat lfP Jig)

Etpound1e1ency

PireentDl

Turbine Sed x-~m( 1

Turbine OutEut RPJl)

Turbine Specific

SeeedrIbullntbull

( 6)

o-9middot1 0-9-2 0-9-3 o-lt)-4 09-$ 0bull9-6 0-9-7 0-9-8 0-9-9 0-9-10 o-9-11 0-9-12

aao 994

111$ 1197 1206 1180 11)21081 982 784 5-49 2)9

0middot45oss o6$ 070 07$ 0-77 (l77 or~ o s06o 8 096

123~ 1402 1$80 1698 17bulllS 168$ 16bull18 ~middot5430 1151 a~J4 9

24middotgt24middot3248 25~25 260 260 259 267 266 26middot1 2S2

sos 577 63-7 671 676 650 621 60036J4

327 178

$) 610AlO 3$

92S 980

102$ 1070 1157middot 1230 1300 137Smiddot

44middot4 soo 523 ssomiddot 540so6 46-5 432 368 274 18~8

J46 176 21-1 255 2802s_A 28 289 288 265 231 168

1-4-1 1-4middot2 1-4-3 1-4-4 1-4-5 1-4-6 1-4-7 1-J-8 1-4~9 1-4-10 1-4-11 1-4-12

10bull48 1231 13-S6 1397 1)821375 1))8 1303 1127 953 683) 51

048 067 o7A07 0 bull79 oa1 oss o bullao osa 0lt)0 096 099

J468 1740 1921 1978 1958 19$1 1911 lSSi162 1)98 1045

603

266 264 262 262 261 2512$7 2$6 24middot7 24-3 233 217

551 660 13middot3155 75-6 7~-97 middot4 72$ 67 51middotJ 44middot9 21middot1

475 605 A4220

875middot 910 970_

1000 1090bull 1166 1243 1330

5816

44middot444middot5 430 427 412 392 329 273 188 l0-7

117 101 204 22$ 2)7245 2562sa 257251 222 179

a-C))

Appendix Ct CALCULATED -DATA ( Ocntinued)

1-6middot1 1023 o$2 14-41 26S 505 41~6 26~

54middot5 13middot3l-6-2 1201 067 1boo 625 47-9 17shy~middot41-6bull3 1296 oA9 1 middot43 26 9 700 so5 20bull 4 l-6-4 l3j5 o 0 19~09 268 71bull3 A5o 514 222 1-6-5 1) 5 o81 19(gt4 271 725 51-5 238 l-66 1398 081 198) 27-0 736 8 S13 252~-middot l-6j 1405 083 199i 211 733 885 $middot06 2$9 l-6 13middot9~ 103 2amp 0 279 71 8 985~ 467 ~-69 1228 1 bull 02 17-SS 270 661 109$ 407 ~3~ l-6bull10 1025 100 lSll 26i 573 1175middot 27~S32middot~l-ampu 153 1-00 llft3 26 444 1270 22 24bull8 1bull6-12 294 100 52a 231 22 3 1360 95 172

1-9bull1 904 048 1275 2J4Z $28 S4$ 459 1$2 1-92 98$ oss 13-92 24middot4 57-0 6JO 49bull1 176 1-9middot3 1110 066 1$76 24middot9 63middot4 I2o 536 21-7 l--9-4 1187 072 1685 251 66$ 5 $$ bull 0 261 1middot9-5 llltJ7 1710 25middot4 67-3 93$ 536 28~20-671middot9-6 1186 o 8 1708 25-7 67) 980 $15 2691-9- 1161 oBo 1660 2$middot3 6$6 990 508 29-1 l~- ll-32 oB) 16sect0 2$8 632 1030 471 291 1-9bull9 109$ oa5 2$7 614 1075 29S~middot 0 4imiddot41-9-10 9~91 oas 262 S$1 1150~ 3 o 292 1-9-11 o9o u57 12JiO 21gt 26-77middot74

-45 26sect ~middot91-912 $69 091 sas 25 middot3 1)0$ 196 2J-8 1-9-1) 220 098 426 2)9 178 1390middot 84 16 6

0 0

Appendx C CALCULATED DATA (Continued)

Turbine Run Generator Generator lurbine Turbine Eft1e1eney Turbine lurbine Spee1f1c

Number Output Losses Outit Input Speed Output SPed middot k_-V KW R _ H_bull_P Percent r Thm HP rpm_ (9) tlo) 11) middot (12 _) (lJI ( ) (1$ (14)

2-9-1 9--46 055 1)62 258 528 580 164 2-9-2 1024 056 248 58 4 665 4 9 191iimiddot48 4~middot0 2-9-3 1132 067 05 2$0 641 795 52q 237 2-9-4 1148 065 1027 2$1 -~8 845 525 252 2-9-5 11 77 oso 16-83 253 6 910~ 522 270 2-9 6 1122 071 1600 251 622 960 47-5 2722-9-A 1092 015 1562 257 608 1010 445 2z12bull9- 1052 079 1514 261 580 1060 41middot7 2 2 2middot9-9 986 o82 ]429 26) 542 1105 372 277 2-9-10 915 086 1340 268 500 1160 334 27-6 2-9-11 638 087 972 254 )81 1270~ 229 250 2-9-12 )28 090 828 259 )19 1295 179 226 2-9-13 192 094 383 2$ 6 150 1370 7 3 152

-3 0

Page 24: The Effect of A Variable Draft Tube Flow Area on the

17

18

turbine is to produce power as etfic1ently as possible

The equation tor the power output of a turbine () Pbull 227)

PaWHe HP (4)55o bull bull Assuming the head 1a constant and a g te located in

the draft tube decreases bhe rate ot flow the power eu

only be increased if the etticiency increases

The ettective head Gn the turbine 1s conventionally

d r1ned as the difference between the auma ot the elevashy

tion head pressure head and velocity head at the entrance

to the turbine casing and the tailrace ($ Pbull 872)

lt ie recognized that the theoretical treatment ot

shock loss as given is highly approximate and serves only

to dictate certain trenda For example the area at xit

rom the wicket g tea CfUl be measuPed with some exactness

but there exists no guarantee that the wateP particles will

complet-ely fill the apace oz- will exit at the establiahed

g te angle The same can be said of the exit trom the

runner blades AssUIlptiona were implied which would indishy

cate that all water particles passing a given croea section

ampH traveling at the same velocity in the same direction

the e alone are autt1c1ent to show 11m1tationa in a theoretbull

1eal approach to the problem

Assume a turbine with ordinary wicket gates tor oonbull

trol compared gainst the same turbine with a gate in the

18

draft tttbe tor supplampment1ng control or the rate ot rlow

Let it also be assumed that the two turbines are opershy

ating at the same point It 1s desirable to predict relabull

tive performance of the two turbines 1 this point of

operation is such that edd7 s hook loss ot reasonable proshy

portions is present in the fir t turbine

~ tull erteot of the shock loss will be exper1 need

by- the fir t turbine

lhe second turbine will derive certain advantages 11

the gate in the draft tube is adjusted to reduce the tlov

1n the proper amount Since they vary a the square ot

the veloo1t7bull the lossabull in the aeroll case wiomiddotket gate

and runner passages will decx-ease aetet-r1ng to Figure 2 1

it can be seen that a decreased velocity v1 w-ill reduce the

eddy shock losa

The ent loss in the dJtaft tube of the second turbine

will be the sum ot the tr1ct1onal loss and the velocity

head at ex1t The velocity head dissipated will be greater

due to the closing action or the gate but the reduoed

t~ictional loss which ia a tunction ot the rate of tlow1

will partially balance this

It 1a entirely possible that the net reduction in

losses in the second turbine will lead to a greater ettibull

oiency and more power output than 4eYeloped by the first

turbine

19

In Figure 3 the plot ot power output against turbine

speed for Curv A~ represents the typical family of curvea

tor a reaction turbine Th b st sp ed is the locus ot

points connecting maximum eft1oiency at each gate opening

The operating speed is the coZUJtant turbine apeed which

passes through the point ot maximum efC1ciencr of the turbull

bine The plot of turbine efficiency against power output

for Curve A is also ahown

It the turbine with flow regulation in the dratt tube

oan demonstrate superior power and efficiency at part loads

the effect would be the same as a shifting or the power

curves toward the condition shown fop Curve B 11 Thisbull

illustrates th ultimate case of the uperpoait1on of best

and operating speeds It will be noted that the pet-form~

of the turbine ot Ourve Bu 1a better than that of CUrve

A at part loads because of ita ability to sustain a relabull

tively high etticienoy ovel a Wider range of power output

o Reguireaegts tort Test Velitication

It is desired to deterra1ne the effect on the turbine

performance b) the addition of a gate in the dratt tube

Th step in the teit will bet

(1 To determine the power output and efficiency ot

the turbine tor wicket gate settings above and below rated

conditione for a wide range ot speed

20

CURVEAbull

TURBINE SPSBD TURBID SPEKD

POIBR OOTPOl

Figure 3 - Turbine Performance Curves

21

22

(2 peat (l) with the gate installed in the drat

tube

(3) middot Converting middot all data to a constant head compare the

powere and effioiencies at the same wicket gate setting and

turbin speed tor the two cbullses

If the ddition or the gate indicates an improvement

in power output and efficiency and the powe~ curve shifts

to the right along the turbine apeed scale the advantage

ot draft tube con~ol of the flow will hav been demonshy

strated

Chapter IV

A E9J11pment

ih turbine used in this test is lJ 5 1nch Pelton

reaction turbine with a rated output ot 30 horsepower under

a head of 56 feet at a speed ot 720 reYolutiona per minute

Views of this turbine are hovn in Figures S and 6 The

turbine is installed on a concrete pad located over an open

channel in the Hydraulics Laboratory at Oregon State Colshy

lege The date of manufacture of this turbine was 1915

The water was delivered to the turbine from a sump

reservoir by two pumps operating 1n parallel Each pump 1a

an 8 inch Pelton double suction centrifugal pump witb a

rating of l$00 gallons per minute at a head ot 75 teet with

a speed ot 1175 revolutions per minute Tbe inlet tlange

ot tne turbine is $pprox1mately 18 feet above the center

line of the pump

A direct current generator was coupled to the turbine

to receive tne power d veloped as shown in Figures 4 and 7 The generator is a Spr gue Electrodynamometer rated at SS horsepower with a speed range of 7$0 to l$00 revolut1one

per minute The classification is type LO 26A 2)0 volta

Figure 5 - View of Test Turbine

Figure 6 ~ View of Test Turbine

and 149 amperes lbe generator ti ld was aepar tely

excited using direct current from a motor g n r tor ampt

(l$ p 4~8)

The power output of the generator waa dissipated in

the water rheostat (3 p 488-489) shown in Figures 9 and

10 The galvanized tank contain d water ot variable d pth

on an electrode ot cast iron m aauring 1bull x 1 x 1

In the initial installation of the turbine it was

intended that the power output should be measured with a

Prony brak bull For th purpoa68 or this teat it was decided

that the brake was too instable and the generator was

substituted The platform for raising the generator the

nee asary two teet for alignment was built out of available

material In this case heavy laminated wood blocks reiashy

torced with other timbers were used and bolted through the

concrete deck (11 Pbull 36-$7)

Due to the light concrete deck the lack ot mas in

the platform and the slight misalignment in the flexible

coupling ao e vibration waa encountered It seemed to

ncr aae linearly to a maximum at the speed of bout 750

revolutions per minute Above this speed no vibPation was

noticeable The vibration waa not se~ere and does not

appear to have materially affected the test results

26

B Intrumentat1on ~ eaeur1ng Devices

The pressure head at inlet to the turbine vaa meaave4

bymeane ot two )6 inch waterbullmeroury manometerbull connected

in series as shown in Figure 8

The terminal voltage ot the generator vas meaeured by

a laboratory voltDleter with a range to )00 yolta and callbull

brated to within 15 Yolta

The armature current bull and hence the line current was

measured by a laboratory ammeter with a range to 150 amperea

and callbrated to w1 thin o 7S amperes

Tae rate ot tlow was established by weight and time

meaeurementa The weighing ank has a capacity ot 121 000

poundsJ the weight belng indicated by Toledo direct reading

scales Timing was done with a hand atop watch with clivibull

aion ot 02 second

he ~ater level in the tailrace was dete~1ned by a

hook gauge lhie was read to the nearest 001 toot

The turbine and generator speeds were eaaured by a

hand tachometer The technique of almost cont1nuoua readbull

ings of the speed gave an error ot no more than 5 revolubull

tiona per minute

c Operational Procedure

Atter the water level in the aump was checked to

insure an adequate auppl7 the puapa were primed and

27

Figure 7 - Test Generator and Plattorm

Figure middot8- Instrument Board and Field Rheostat

28

started After venting they were valved for operation 1n

parallel

The motor generator set was started to supply the

field current and the circuit breaker was closed Water

wa added to the water rheostat to the level shown in

Figure 10 ~ field current wae minimized by cutting in

all the f ield resistance in the field rheostat of Figure 8

The l2 inch gate valve shown in Figures 5 and 6 waa

slowly opened and the turbine and generator brought up to

speed The 12 inch gat valve and turbine were vented and

the pumps were checked to insure neither had lost ita prime

lhe water rheostat offers very steady load 1f the

water level is essentially constant and the water temperabull

ture 1a fixed () p 488~89) In order to maintain this

constant temperature it was decided not to circulate the

water in the rheostat but rather to allow the water to

boil thua achieving the desired result A standing wave

was set up on the face ot the electrode by the boiling

action but a atable load was eatablished except at very

low water leYels where th11 agitation led to fluctuationa

in the line current

After putting the turbine and generator on the line

maximum power was dissipated in the rheostat by redueing

the turbine speed to between oSO and Soo revolutions per

minute Salt vas added to the rheoetat wat r to increasemiddot

29

Figure 9 - View of Water Rheostat

Figure 10 - View of Water Rheostat

Separate Field ExcitationFrom Motor-Generator set Compound Water-Mercury

---shy

re Manometer

I Q)

~ 0

~

Book Gauge

Open Channel

I

Slap Reservoir

Figure 11 - Wat~r Flow Diagram and Electrical Layout

31

waiting pe~iod ot perhaps an h~ followed

while the boiling point or the water wbulls reacbe4 During

this ti+ne the manometer was vented end eheoked electrical

measur1ng 1nstlUments were connected end the hook gauge was

adjusted tor elevation

It required about two- houtte tor the generator to reach

its normal operating tempe-ratu~e_ After the water in the

rheostat and generator had reached their operating temperabull

turea it was possible to begin the taking of data

The only vaPiable which was controlled wee the turbineshy

generator speed However the upper l1ut1t of safe line

current was slightly over 100 ampJilPampPes and the eireuit

breaker would open when the current reached lOS ~ere bull

Control was exercised by means ot regulating the water

level and salt 1n the water rheo tat and the res1stsnoe of

the tield rheost t~

The etfeet ot each type ot regulation on the three

variables is shown below

Volta Aaperebull Speed

Inc Dec Inc Dee~ Inc Dec

Wa~e1 Level Inc Dec~ X

X X X X

X

Salt Concentration

Inc Dec X

X X X X

X

field Resistance

Inc Dec

X X

X X

X X

32

Jlot all methods gave the ame amount ot change in a

given variable and a period of experiment and trial led to

the following scheme starting the rune with the lowest

turbine speed the water level was high with a high amount

ot salt and the field resistance was cut completely out

Aa it became necessary to increase the speed tor each

aucceasive run either cutting in t he field resistance

decreasing the salt concentration or lowering the Vater

level would produce the desired result However decreasbull

1ng the salt concentration had to be done Without a net

gain in water which led to a tluahing procedure that was

not particularly good because cold water was introduced

which required time to heat to the boiling point Cutting

1n additional field resistance was a good method but th1a

increased the amperage possibly to the point of opening

the circuit breaker Lowering the water level was aatiashy

factol1 until the level got too low causing the current

fluctuation previously mentioned Actually it turned out

that a combination of lowering the water level and cutting

field resistance in would carry the speed from ita minimum

to 1ts maximum value it the proper choice were made each

time the speed waa to be changed At the conclusion of

each aet of runs at a high speed the water level would be

low and the field resistance high

33

TURBINE

PAD AND DECK

TAILRACE

WATER SURFACamp

CONCRETE

DRAFT TU1B INSERTS

7 5( DRAFr TUBE

FLltJI ARIA

5~ DRAFT TUBE

FLOI ARSA

Figure 12 - Sketch of Draft Tube and Test Inserts

34

Figure 13 - View of Draft Tube Insert

Figure 14 - View of Draft Tube Insert

D c __ ~s_middot hedu_le of

A number was assigned to each run The fi~st number

applies to the draft tube tlow areas

1 bull 100~ flow area or 0~ oonatriction

2 - 7S tlow area or 2$ conatr1ct1on

3 SoC flow area or so~ constriction

The second number refers to the wicket gate openings

9 over gate opening

6 bull intermediate gate opening

4 bull one h lt gate opening

The third number 14entif1ea the location of the particular

1Wl in a set ot rona made at a given dratt tube tlow area

and wicket gate opening

fnua run number 1bull4bull10 would identity this as the

tenth run ot a set made at halt gate with 75 ot the draft

tube t1ow area

Rune w re made tor a g1yen dratt tube condition

Firat tor tull 41-aft tube flow area seta ot rune were

made for the overgate halt gate and intermediate gate

conditione An insert was placed in t he draft tube and

rune based on the same gate conditions were made tor the

7S~ draft tube flow area case The insert was then changed

to allow only $~ draft tube flow area

The inserts are sketched 1n Figure 12 and photographed

ln Flgurea 13 and 14 They oonaisted of circula~ segments

36

or l2 ineh plywood mount 4 on wooden legs 10 inches high

The 1nse7te were placed in position and secured by th use

ot a-clamps on the legs and the outside ot the bottom of

the draft tube The obvious disadvantage to this method

waa the neoeasity tor draining the water from the tailrace

tor a change ot 1naert The advantage vas of course the

simplicity ot design and construction

Chapter V

DATA-A Original Data

The normal data-taking crew consisted or two men

Assuming adjustments having been made to secure a certain

turbine speed (aee section on Operational Procedure) one

man would take semi-continuous speed readings with the hand

tachometer until a state or rotational equilibrium was

reached This could be only a period or two minutes up to

ten or tifteen minutes As soon as steady speed was

assured the data taking would begin The second man went

to the weighing tank Where a minimum ot three weighingamp

were made The requirement was to get three consecutive

readings such that the ditterence between tbe smallest and

largest time did not exceed 04 seconds The time to

collect a given weight ot water was then assumed to be the

arithmetic average of the three times He then went to the

hook gauge determined the hook elevation and then

recorded the data on the data sheets The first man meanshy

while had taken readings of the line voltage line current

and manometers and checked the turbine speed by multiple

readings During the length of the run all values were

38

checked to determine mean values for recording

The minimum length of one run was about five minutes

If one or more measure ants tended to drift during the run

all values wer discarded and a new run began as soon aa

qu111br1um was stabl1shedo

B -0-al_e_u_l_a_t--d Data

The h d on the tu~bine 1 defined by

($)

The maxtmwm velocity V4 was equal to about o8 tampet per

secon4 which makes it a negligible quantity when converted

into velocity head

An engineerbulla level was used to deterine the d1ffePshy

ence 1n elevation between the compound water-mercury manoshy

meter and the hook gauge Using this value the equation

for turbine bead becomes

where z4 is the hook gauge reading

The rate of flow 1 cent

w weight or water collected average time to collect

The inlet velocity v1 vas calculated by dividing the

weight rate or flow by the specific weight of water and the

)9

area ot ~e inlet pipe This was equivalent to dividing

the weight rate of flow by 490 Then the power input to the turbine is equal to

WHpin rri

10 (6)

Also

(P ~ut) Turbine

(P out) + Generator

(P lost) Generator

The power output of the generator is simplJ the

produot ot the terminal voltage and the armature (line)

curPent The power lost in the generator can be subdivided

into copper losses and stray power losses lo evaluate

these cunes based on losses of an identical generator

11leampsured by the Department ot Mechanical Engineering were

used The loss curves are reppoduced in part in Figures

15 and 16

Determination ot generator losses proceeds as tollowau

(1) From Figure 15 detem1ne the vo1tage drop in the

armature circuit using the temperatures of 1220 F and the

meaaured current

(2) The induced voltage is t~e sum of the terminal

voltage and the voltage drop 1n the armature circuit

() Entering the induced voltage and the turbine speed

into Figure 16 the stray power loss can be determined

(4) The copper lose can be evaluated from Figure 1$

using the measured current and the temperatlll-e of 1220 P

40

25 ~------~--------~--------~------~

U) -U) - 20

f-4 ~

-~ -gt 0

0

VOLTAGE DROP

~ - i -

- bullbullbull bull - -middot-middot -+ ~- + -t--+ ~ - ~ middotbull ~-~ middott- -+----- _ -4 middotmiddot- --~-+-t---r~~ ~--+t-t- - ---t-c-++~-ulf--

0 50 75 100

Figure 15 - Curves of Generator Voltage Drop and Copper Loss

41

1200

1000

800

600

800

0

0

~-

middot--~ 1shy --1 + bull l

100

I -

150 200

IIDOOED VOLTAGB (VOLTS)

Figure 16 - Curves of Generator Stray Power Loss

_ j

-bullshy -L---- shy middot -shy

250

- r

42

(5) The generator los os equal the sum of the eopp r

loss and stray power loss

~e efficiency or the turbine is taken as

etticiency u e =P out (8)Pin

~ample pound Determ1n1gg turbine Power Output

The following data are taken trom that ot Run 1-9-1

Line voltage 1040 volts Line current 870 amperesSpeed 355 revolutions per minute

The induced voltage 1a determined as follows

Line voltage 1040

Voltage drop 90 using Figure 15 with line current of 870 amperes and temperature ot 122 degrees)

Induced Toltage 1130 volta

The power output of the turbine is determined as follows

Generator output 90$0 (line voltage z line current)

Oopper loss 7 (using Figure 15 with line current of 870 amperes and temperatUe or 122 degrees)

Stray power lose 470 (using Figure 16 with speed ot 355 revolutions per miDUte and induced voltage or 1130 volts)

Turbine power output 9527 vatta

or turbine power output 1s 12z2 horsepower

43

The conversion of the calculated data to a constant

head is based on the conventional assumption of constant

efficiency regardless of turbine head For a constant head

ot 81 teet a purely arbitrary figure the tollowing relashy

tionships are ass1lJiled to be true

I ____L (9) (i)l72

(10)

For these two values the specific a peed may be combull

putedt

N t Jt VPt (11)8 243

Chapter VI

~RESULTS

A -Pr_e_ae_n_t_a_t_t_o~n g Reaultbull

Graphical presentation ot the results ot this te1t

are given as follows

Figure 17 -Turbine characteristics with 100~ dratt

tuba 1low area

Figure 18 - Turbine characteristics with 7S dratt

tube tlow area

Figure 19 bull Comparison ot power and etticiency at

over gate conditions between 100 and

75~ draft tube flow area

Figure 20 bull COZQparison of power and ettic1ency at

halt gate conditions between 100~ and

7S~ draft tube flow area

Figure 21 bull Comparison of power and etticiency at

over gate condition between 100~ and

So dratt tube tlow area

Figure 22 - Comparison in variation ot apec1t1c

speed between 100 and 75~ dratt tube

tlow area

50

45

20

-bull - 1--shy40

bull J-~ 30

~ ex

~ 20

~~ ~ -)q

I

~ - _

- -

10~ OF DRAFT TUBE FL(Jif AREA

CONSTANT HEAD OF 8l FEST10

POIER OUTPUT EFFICIENCY SPECIFIC SPEED

0 ~--------------_--------~------~------~ 400 600 800 1000 1200 1400

TURBINE SPEED (RPM)

Figure 17 - Turbine Char~cteristics with 100 Draft Tube Flow Area

50

46

-bulllle

~ 7 ~ OF DRAFt TUBE FLOW AREA

0 -~~-rl C05STAMT BEAD OF 81 mET 1J~

POIER OOTPUT ---+- ---o ~_H EFFICIDCY ~ I shy

bull ql SPECIFIC SPEKD - ~ -

bull ~ J 10 L rmiddotr- r- -

bullz- I

~~ 30 ~~--~----~~-

20 ~ ~ middot-shy

26

~~ 25

~0 ~r-----i (

Tbull -bullshy

400 600 800 1000 1200 1400

TURBINE SPEED (R PK )

Figure 18 -Turbine Characteristics with 75 Draft Tube Flow Area

47

EFFICIENCY 60

1-----shy

-~ 50~--~--~~-~middot middot middot middot r~-~----~~~~---4~-r~-~~gtt

II

POWER~ J ~ bull bull

u I

sH

40~------+-------+---- -~~--~~-~~~~

~----~rl 1 bull

I

I

0~--------------~------_------~--------

~ -OVER GATE CONDITION

COIJSTANT HEAD OF 81 FEET

0 o 10~ DRAFt TUBE

_-- _ 7~ DRAFT TUBamp FLON AREA II

10_~-----+--------r-------r----~~

400 600 800 1000 1200 1400

TURBINE SPEED (RPM)

Figure 19 middot - Comparison between 75 and 100 Draft Tube Flow Areas of Power and Efficiency at Over Gate Conshydition

48

t

bull --4 r ~- ~ middot~

70 1-----------+-~~~~~+middot ~ ~~ middot middot -~~--~~--------~~----~-+1

-~-

Atbull bull

lla-

60

amp0

40

20

10

oampOO

t _ - - ~-+- - -~-

l2 GATB COJIDITIOJJ

COJISTABT HJW) OF 81 JBET

o 0 lOQ( DRAFl TUB8 FLOI AREA

e-- - e 75 DRAFT TUBE FLOW AREA

800 1000

- r-

~

TURBIbull SPBIID (RPII)

Figure 20 - Comparison between 75 and 100 Draft Tube Flow Areas of Power and Efficiency at Half Gate Conshydition

49

60

50

-40

bull 30

IIQbull

20

10

0

400

- t - ~

EFFICIENCY

_J bull - bull bull

~ r r middot t -+ shy L -t -

OVER GAD COliDITIOI

CONSTABT BEAD OF 8l FBB

o o 10~ DRAFt TUBE FLOI ADA middot--- 5~ DRAF TUBE FLQPi AREA

600 800 1000 1200

Figure 21 -Comparison between 50~ and 100~ Draft Tube Flow Areas of Power and Efficiency at Ove~ Gate Conshydition

50

25

20

15

10

0

Figure 22

~- T -4 -t- -l --~-

t-~ I

middot --~- t ~---- _ __ _ + --

----~- --r-- --

~-=J-~-=-~ -==~ _ ~- -- ---f---1 - shy

CONSTANT HEAD OF 81 FEBT

o--o 1~ DRAFT TUBE FLltll AREA

75C DRMT TUBK FLCIJ AREAmiddot--middot-middot 600 800 1000

TURBINE SPEED (RPK)

Comparison of Specific Speeds for 75 and 100 Draft Tube Flow Areas

51

B Discussion 2 Result

Consideration of Figures 17 and 18 indicates the

overall eftioi ncy pattern or hill is significantly or

rounded for the 7$~ flow area than for the 100~ flow area

bia implies a greateP efficiency is possible at speeds

leas than or greater than design speed with an insert in

the draft tube However the muilDum efficiency is lemiddotas

Direct comparison at over gate conditions is made in

Figure 19 ~e same general trend is noted tor both the

etticiency and power curves for the 7$~ flow area case

The eurves show higher values at overspeed than do the

correaponding cWvea for the 100 flow area case It ia

not clear whether the curves have been shifted by the dratt

tube constriction or whether the curves simply bulge past

the normal curves at both overspeed and underspeed condishy

tions The power curves apparently peak near the aeme

point bullalthough maximum power is still obtained with the

normal draft tube area

For the comparison at halt gate operation shown in

Figure 20 a general improvement has apparently been made

by restriction of the draft tube flow area At every speed

the etticienoy and the power is greater for the restricted

tlow case The two ett1o1ency curves and two power curvea

are practically parallel throughout the speed range ot

teat

As the flou aroa i e decreased still farther a s1gn1

ticant change appears Reterr1ng to Figllle 211 tor the $0

flow area curves it a obvious that exit losses have

become excessive at the overgate condition because the

efficiency and power are everywhere leas than tor the case

of normal draf t tube area

Earlier it was pointed out t hat 1t the r esult s 1nd1bull

eated an increase in both power and ef tieiency- t hen it

could be assumed tha t the additional los s i ntroduced with

the draft tube insert is less than the diminished losses

due to leas shock losa and water passage losses For the

places where both the efficiency and power have been

increased we can assume that the insert has improved turshy

bine performance

For the places where the power haa been decreased

nothing can be said as to the elimination of ampbock loss

because the new lose present with the drat tube insert has

overshadowed any gains in eftecti Ve head upatJ-eam of the

insert

Near the peak of the efficiency hill howeve~ it may

be pointed out t hat shock loaa ie a minimum with a normal

draft tube and the insert merely adds an additional loss

with the resultant decrease in maximum efficiency tor the

7$~ flow area case

Perhaps the most s1gn1ticant set of eurves is shown aa

53

Figure 22 In this graph values of specific speed tor the

75 and 100~ flow area cases for both over gate and one

halt gate openings are plotted against turbine speed At

every speed and both gate openings the value ot specific

speed for th 75~ flow area case is greater than that for

the 100 t1ow area ease

Since the head is a constant for both situations this

may be interpreted in either of two ways trom equation

(11)

(1) For the same turbine apeed restriction of the

draft tube t1ow area resulted in greater turbine power

(2) For the same power amputput the turbine with 75~

draft tube flow area operated at a greater speed than did

the one with 100 flow area

Since the required diameter of a turbine varies

inversely with the speed the second interpretation could

be stated such that a smaller turbine could be used to

develop the same power output

Whether viewed trom the aspect of increased power

greater speed or reduced size the performance of the turshy

bine with reduced draft tube flow area is superior to that

with the nolmal flow are in the draft tube

The curve of specmiddotific speed versus turbine speed for

the so draft tube flow area case at over gate cond1t1ona

was not included in Figure 22 This curve lies below that

for the 100~ flow area c se at all speeds

In elaboration ot the second interpretation of Figure

22 attention is directed to the relative magnitudes ot

increased apee1f1c speed tor the two gate openings Assumbull

ing that the increase in specific speed implies a shift ot

the power curve to the right along the turbine speed scale

the power curve would be shifted more tor tbe halt gate

opening than tor the over gate opening

It thia trend could be extrapolated to the other gate

openings the tendency can be seen tor the line ot beat

speed to rotate toward the line of the operating speed as

illustrated in FigtU-e ) The advantage of this has already

been discussed

This particular turbine has a low specific speed tor a

reaction turbine Aa the rated value of apecitic apeed tor

reaction turbines increases the line ot beat speed departs

even more radically from the line of operating bullpeed It a

test similar to this were conducted on a reaction turbine

ot gleater specific speed it is pJobable t hat the rotation

ot the line of beat apeed would become more p~onounced

The scheme used in th1a teat had two obvious dr wbull

backs The first was the decision to leave all the wicket

gamiddottes installed tor all conditions ot the draft tube

These gates predominated in control of the tlow The

inserts added to the draft tube merely acted as auxiliary

55

contrGla

The aecond drawback was the choice or device to place

in the draft tube The reasons foll selection of this type

of device have been previously mentioned It is to be

anticipated that adaptation ot dratt tube flow control

would result 1n a better device for an actual turbine

installation Such apparatus might take the form of a

pneumatic bladder or a h7drau11oally operated variable

venturi section in the draft tube It is conceivable that

the gate as used in this test might be adapted also

Chapter VII

OONCLtJSIOfS

From the results of this test the following eonolubull

e1ona aa to the effect ot a variable draft tube flow area

on the performance or a r action turbine may be drawn

(1) The effect ot a variable draft tube tlow area 1a

generally favorable upon the operat1Gn ot a reaction turbull

bine because or the tendency tor the line or beat speed to

rotate toward the line ot operation This resulte in

better performance of the turbine at partbullloads

(2) he etf1o1ency eh111 tor the turbine beeomaa JDore

tlat at the top leading to a smaller max1JilWD effic1enc7

but e reater etticieney at other pointe of operation with

the insertion ot an auxiliary control ror the rate ot tlov

in the draft tube

(3) The power output of the turbine will increase at

over speed over gate conditione as well a at part gate

conditions with the proper amount or draft tube eonatr1cbull

tion or flow

(4) It is possible to eliminate at least partially

eddy type shock loss by tho introduction ot flow control

in the draft tube

BIBLIOGRAPBl

1 Addison Herbert A treatise on applied h-draul1cs New York Wiley 1954 724 Pbull

2 Allen o M and I A Winter middot Co111parative testa on experimental draft tubes Tranaact1ons ot the American ociety ot Civil Engineers 87t893bull970 1924

3 Barrows a E Water power engineering 3d ed ew York McGraw-Bill 1943 791 Pbull

Bovet G A Modern trenda in hydraulic turbine design4middot in Europe Tranaactions of the American Society ot Mechanical Engineera 75975bull993 1953bull

s Oreager William P and Joel D Justin Hydroelectrichandbook 2d ed New York Wiley 19$0 1151 Pbull

6 Daily Jamea w Hydraulic machinery Int Hunter Rouses Engineering hydraulics Hew York Wiley 19$0 p 8$8bull99

Daughertybull Robert L Bydraulie turbines ew Yorkbull7middot MoGrav-Hlll 1920 281 Pbull

8 Daugherty Robert L Inveat1gat1on of tne performance ot a reaction turbine ~anaactiona or the American Society ot Civil Engineers 7811270bull1304 1915

9 Davie L M Model and prototype testa Int Trend in hydraulle turbine practice symposium lranaactions ot the American Society ot Civil Engineers 1o63S3middot368 1941

lfJ Doland James J Hydro power engineering Hew Yorkbull Ronald 1954 209 Pbull

11 Gandy Theodore s and Elmer c Schacht Direct curshyrent motor and generator troubles operation and repair New York McGraw-Bill 1911 293 Pbull

12 Gibaon Arnold H Hydraulics and ita applications5th ed London Constable 1952 813 Pbull

58

13 Button s P Component loases in Kaplan turbinebull and The prediction of efficiency from model tests Probull coedings of the Institution or Mechanical Engineers168743-762 1954

14 Knapp R T~ Oavit t1on mechanics and its relation to the d sign or hydraulic equip ent Proceedings or tne Institution ot Mechanical Engineers 166150bull16) 1952

15 Langsdorf Alexander s Principles of direct curHnt mach1nee 5th ed New York r~cGrawbullH1ll 1940 746 Pbull

16 Lsrner Chester w Characteristica of modern hydraubull lie turbines Trans e~ions of the ~~erican Society ot Civil Engineers 66306-386 1910

17 Linsley Ray K Jr and Jobulleph B Franzin1 Eleshyments of hydraulic enginebullring New York McGrawshyBill 19$5 $82 Pbull

18 Mead Daniel w Hydraulic machinery llev York McGraw-Hill 1933 396 Pbull

19 ead Daniel w Water power engineering New York McGrawbullRill 191S 843 Pbull

20 Mockmore Charles A Part gate operation at water turbines Corvallis Oregon State College Department ot Civil Engineering 1933 11 numb leaves (Unpubshylshed typescript)

21 Mockmore Oharles A Flow characteristics in elbow dratt tubes Transactions of the Amez-ican Society ot Civil Engineers 103402middot464bull 1938

22 Moody L F Hydraulic machinery In c v Davis Handbook ot applied hydraulics New York McGrawshyHlll 1942 1082 Pbull

2) Ptau At-nold Hydrbullulie turbine handbook ld ed Milwaukee AllisbullOhalmers ManufactUIing Company 1948 70 Pbull

RheingalUI w J Recent developments in Francis turshybines Mechanical Engineering 74189-196 1952

25 Russell George E Hydraulica 5th ed New York Henry Holt 1942 466 Pbull

26 Safford A and E P- Hamilton American mixed tlow turbine and ita setting Tranampactions or the Amerieal Society of Civil Engineers 851237bull1)56 1922

27 bull Spannhake W1lhe1Dh Problems or modern pump and tur b1ne design Transactions of the American Society of Mechanical Engineers 56e22$-248 1934bull

28 Sutherlandraquo R A Better ethod or representing and middot tudying water turbine performance ~ansaetions ot thmiddote American Society of Mechanical Engineers 68t675bull 686 1946

29 Teats ot five models or draft tubes tor turbines Engineering News-Record Pbull 182-184 Aug 2 1923

30 White w M American hydztaulic turbines Mechanical Engineering S2t390bull39S 1930bull

31 White w M lhe hydraucGne rega1ner1 its developmentand appl1eat1ons 1n hydroelectric plants Meohanlobulll Engineering 43t37Sbull380 1921 middot

32 Winter I A Economic principlebull in designbull Int Trend in hydraulic urbin practice bull a ampoeiumTranaaot1ona ot the American Society ot Civil Engineerslo6332bull3S2 1941

33 Wiel1cenua G F Fluid mechan1ca or turbo-machineryNev York McGraw-Hill 1947 613 Pbull

APPENDICES

c

Appendix A

NOATIOB

A Angle between the absolute velocity vector and the tangent to the rwmer Subscripts 1 and 2 refel to entrance and exit ot the runner blade

B Angle between the relative 1elooity vector and the tangent to the rwmer Subscripta 1 and 2 refer to entrance and ezit or the runner blade

Angle between the tangent to the runner blade tip and the tangent to the runnel- Subscripts 1 and 2 reter to entrance and exit of the rt1rmer bladebull

Blade angle-gate opening conetant defined by equation (1)

e 09erall efficiency

g Gravitational acceleration assumed constant at 322 teet per second per second bull

H Turbine head detined by equation ($)

m Exit loss coeft1e1ent

Turbine speed expressed in revolutions per minute

Turbine speed under a constant head of 81 teet

specitic apeed of the turbine under a constant head ot 81 teet

p Power output in horsepower ot the tvbine

Power output of the turbine Ulder a constant head ot Sl teet

Pl- Pressure head at entrance to the tUlb1new

l1 Peripheral velocity ot the runneP Subacr1pta 1 and 2 refer to entrance and exit ot the JUnllampr blade

62

v Relative velocity reaulting trom the combination ot the absolute water velocity V and the runner periphshyeral velocity u Subscripts 1 and 2 refer to entrance and exit ot the runner blade

v] Relative velocity vector necessary to produce a tanbull gential entry into the runner blades

V Absolute water velocity Subscripts l and 2 refer to entrano and exit ot the runner blade

v2 Velocity head Subscripts 1 and 4 reter to the ~8 entrance to the turbine and the tail~ace wate~

w Unit weight ot water assumed constant at 624 pounda per cubic toot

V Weight rate ot flow in pounds per aeooncl

XX Velocity component ot ahook See Figule 2

Z Elevation head Subscripts 1 and 4 reter to entrance to the turbine and the taibace water surfacebull

Appendix B ORIGINAL DATA-Run

lfwnber

0-4-1 0-4-2 0-4-3 o-4-4 o-4-S o-4-6 0-4-7 0-4-8 0-4-9o-4-lo o-4-11 o-4-12 0-4-13

o-6-1 o-6-2 06-3 o-6-4o-6middotS o-6-6 o-6-7 o-6-8 0-6-9 o--6-lo o-6-11

Speed

rmiddot2middotbullmiddot(1)

336 38$ 451 S$9 620 669 6lt)$ 120 787 860 932

102imiddot109 bull

352 355 443middot 543middot 620 654AJs32

911 1001 1111

~essure Head rt (2)

410 410 416 426 431 43-7 439 44-9 452 467 482 soo $1 bull $

350 351 35middot7 )66 37-9 37-9 392 41 bull 3 43middot3 460 489

Elevation Bead

fjj $7 $7 $7 $7 $7 $7 51 57 5-15858 $8 58 56 56 $6565656 51 575As5a

Velocit Head

flj 07 07 07 06 06 06 06 os 05 os0404 03

09 09 oa o8 o8 os 07 07 06 o~o

Total Head rt ($)

47middot4 4A44 o 489 49-4 soo $02 $11 $14 $29 5imiddot45 2 576

41 bull $ 416 421 430 44middot3 44middot3 456 47-7 496 523551

Plow

lbtjec

326 324middot317 311 306 30029middot28 middotmiddot middot 386 275middot260 240 218

359 36~35 bull 349 345middot 339 330 318 300 273 240

Line Potential

vyqjbull 1060 1220 ~-0o 1920 2150 2000 2$60 2000 1940 18)015io11 o

1000 1100 139bull5 1760 1925 16$0 1620 1610 1540 1330 870

Line Current

amlscs 960 900 830 740 730655 70bull 0 530 660 600 5imiddot54 6 )60

982 930 860 780 ~3-545

79-5 74-5 670 560 370

P

Appendix B ORIGINAL DATA (Continued)

Run Number

Speed

Pbulltmiddotbullmiddot )

leasure Head ft(2

Elevation Head tt(J)

Velocity He-dfmiddotj

Total Bead tt($

Flow

lbstsec( )

Line Potential vo~ta( )

Line Current

amjs (sect

0bulllt)-1 0-9-2

3ll6 398

28o ~~1

$6 56

1o 10

346 347

390 365

1ooo 1190

aao 835

0-9-3 0-9-4 o-9-S

472 565 632

292 305 312

$6 s6 56

10 o9 o9

)$8 J7~o 37~7

381376 37o

1)6614oo 141o

820 ass ass o-9-6 0-9-7 0-9-8 o-9-9 0middot9-10

680 120 762 844 920

)24337346 366 390

56 $6 56 57 $7

09 os o8 oa 07

)89401 410 431454

367~ 357348 34o 322

1400 1J6o l36o 1310 1170

843 820 7957So 67~0

0-9-ll 0-912

1001 1100

41 bull 7 45-3

s 7 6~0

06 os 480 $18

299 268

980 65$

560 36~5

1-4-1 1-4-21-4-l1-4shy1-4-5 1-4-6 l-4-7 1 4-8 1-4-9 1-4-10 1middot4-ll 1-4bull12

354middot452 562 62q 674shy102 752 760- 863 932

1022 1100-

)82389 4014oa 416 41--7 423 428 44-2 45-7 486 49-2

51S757 51 5-7 5middot15zs sa $8 58 59

07 07 06 06 06 06 06 os o bull o 04 o J

446 45-)46middot4 471 ti7-9480 q86 491505 $19 548 55-4

)28 320 311 306 300 295 291 286 269 2582iimiddot21 bull

1080 14Lo 1550 153-5 1470 141-0 1385 1310 1310 1230 1120 855

970855 875 91-0 94~0 975 966 995 860 77-S 610 4fo

0 ~

Appendix B ORIGINAL DATA (Contirmed)-Run Speed Pressure Elevation Velocity Total Flow Line Line

Number Head Head Head had Potential Current rtjjmbull t~ bttec vyfs am~a12) ( ) ti fli 8

1-6-l $6 33$ $6 0bull9 400 364 1100 93 0 1-6-2 41 34laquo2 $6 oa 406 JS7middot iios a5s l-6-3 500 3~0 5bull6 os 356 1 1 o aos 41middot~1-6~4 35bull4 5-6 oa 41middot 352 16~0 82 0 5~1-6-5 5 bull 36_2 Sbull6 08 42bull6 349middot 161 ~ 0 86~0 1-6-6 622 366 $6 oe 43bull0 345middot 158 0 88~$ 16-A 649bull 37bull1 56 os 43-S 342middot 1570 895 1~- 386 57 07 46-0 192 ) 125A44 333middot 1-6-9 3) 404 5middot1 07 468 317 1620 675 1610 911 42-4 5-7 o6 48-7 298 168 0 61 0 1-6-11 999 451 56 os Sl ll 276 ~2-0 530 1-612 1115 485 58 04 54middot7 238 90 )3 0

1middot9-l 355 279 56 10 )45 385 1040 870 1-9-2 399 28J $6 10 )49 38$ 1140 86 5 l-9-3 ~ ao 291 56 ~0 35middot1 J8J_ JJ6o 815 1bull9-4 579 303 56 09 )68 375middot J4JO 830 l-9bullS 40- 313 )6 09 31middot8 370- 1460 82~0 1-9bull6 679 2) 56 09 3 bull8 364middot 1670 710 l-9-7 682 319 56 o9 384 ) 62 1460 79 5 l-9-8 724 33middot5 56 o8 399 3$6 bull 1480 76 -5 1-9-9 762 34middot3 $6 0 bull 8 407 )48 14910 13middotS 1-9-10 833middot )60 5middot7 os 42$ 339 144$ 686 1-9-ll 926 39middot1 5-7 07 455 318 1290 600 1-9-12 1000 41middot3 0-6 476 298 1115 510$ ~ 1middot9-13 1105 452 s o4 $14 2$6 710 )10

~

Appendix Bt ORIGDIAL J (Continued)

Run Speed Pressure Elevation Velocity Total Plow Line Line Number Head ltead Head jlamp$d P()ten~ibulll Current

r~~~m ft ft lbs~seo voltattj rgj twimiddot t 1 t2gt lt3 ou t ( rt

2-9-1 384 289 S 6 10 35 5 1400 1170 810 2-9-2 443middot 29$ $6 ltimiddot9 360 379middot 11(0 87$ 2-9-J 536 30bull 3 sc 09 )68 374middot 1)40 84 bull) 2-9-4 571 306 $6 09 3~1 372 120bull 0 955 2-9-5 623 316 S6 09 J l )6S UJSo 77$ 2bull9-6 669 327 S6 09 )92 )61 1240 905 2-9bull7 712 )39 56 os 40-3 351 12(0 86 bull0 2-9-8 ~5$~ J48 56 oa 412 348 1290 81 bull ) 2-9-9 04 )63 56 oa 42-7 339 12ltJO 76$ 2middotmiddot9-10 8$2 376 5middot1 07 440 33~- ~ o 710 2-9-11 955 394 5-1 o6 457 300 1100 506 2middot9-12 1000 421 $7 06 48middoti 295 1020 $18 2-9bull13 110~ 463 56 05 $2 267 620 3~0

oshy0

Appendix Gt CALCULATED DAgA

Turbine Run Generator Generator Turbine Turbine Efficiency Turbine Turbine Specit1c

Number OutputKWlt21

Loa~Jes KWlol

Outut K bull (H)

Input RP 12)

middot Percentlt13gt

Speed r~Jmiddot(

0ltput HP ~1

Speed r-m

( 6) middot

o-4-1 0middot4-2 0-4-3 0-4-4 0-4-5 0-4-6 O-qmiddot7o-4-8o-4-9 0-4bull10 0-4-11 o-4-12

1018 1o9a 1220 1)62J40214oa1J4oo 1357 1320 1164 997 718

046 o59 071 092 096 1071oo 134 104 100 109 107

14261sso 17)01948 2008 20322011 1999 19 09 1708 14-84 11o6

281279 27-7 276 215 273271 268 268 26h 258 24-5

soa 555 62$ 705 7)1145 742 74-6714645 51s 45-1

440 sos 585 720 195 sso sao 9$$ 985

1065 1135middot 1230

318 357 319 416 422 419412 39middot9 378 324 260 191

102 12bull4 148 191 21bull 3 22o 233 249 24924middot9 238 221

0-4middot13 418 104 699 228 306 1300 117 18)

o-6-1 982 045 1376 271 $08 496 376 124 o-6-2 o-6-3 G-6-4o-6-5 0-6-6

1023 1200 13 73 J415 139h

051 0middot66 oaa ()bull 96 088

14-39 1696 1958 2026 1986

276 27middot4 273 278 274

$20 61 8 717 7)0726

q95615745 8)5685

390 ll5middot3 sos soo 490

127 170 218 243 2$$

o-6-7 o-6-8 o-6-9o-6-lo

1288 1199 1032 7-45

o9o 094 09$ 096

1846 1733 1511 1128

274 276 271 260

67S 629559 43middot4

980 1085 1165 1245shy

436 )83316 21bull 7

266 276 270 239

0-6-11 322 1oo 566 2141 2JS 1350 101 177 0 --4

Appendix C CALCULATED DAlA ( Continued)-Run

Number Generator Generator

Out2ut Losaes xw LW- 12gt (lO)

Turbine Out2ut

ltPlJ

Turbine Inat lfP Jig)

Etpound1e1ency

PireentDl

Turbine Sed x-~m( 1

Turbine OutEut RPJl)

Turbine Specific

SeeedrIbullntbull

( 6)

o-9middot1 0-9-2 0-9-3 o-lt)-4 09-$ 0bull9-6 0-9-7 0-9-8 0-9-9 0-9-10 o-9-11 0-9-12

aao 994

111$ 1197 1206 1180 11)21081 982 784 5-49 2)9

0middot45oss o6$ 070 07$ 0-77 (l77 or~ o s06o 8 096

123~ 1402 1$80 1698 17bulllS 168$ 16bull18 ~middot5430 1151 a~J4 9

24middotgt24middot3248 25~25 260 260 259 267 266 26middot1 2S2

sos 577 63-7 671 676 650 621 60036J4

327 178

$) 610AlO 3$

92S 980

102$ 1070 1157middot 1230 1300 137Smiddot

44middot4 soo 523 ssomiddot 540so6 46-5 432 368 274 18~8

J46 176 21-1 255 2802s_A 28 289 288 265 231 168

1-4-1 1-4middot2 1-4-3 1-4-4 1-4-5 1-4-6 1-4-7 1-J-8 1-4~9 1-4-10 1-4-11 1-4-12

10bull48 1231 13-S6 1397 1)821375 1))8 1303 1127 953 683) 51

048 067 o7A07 0 bull79 oa1 oss o bullao osa 0lt)0 096 099

J468 1740 1921 1978 1958 19$1 1911 lSSi162 1)98 1045

603

266 264 262 262 261 2512$7 2$6 24middot7 24-3 233 217

551 660 13middot3155 75-6 7~-97 middot4 72$ 67 51middotJ 44middot9 21middot1

475 605 A4220

875middot 910 970_

1000 1090bull 1166 1243 1330

5816

44middot444middot5 430 427 412 392 329 273 188 l0-7

117 101 204 22$ 2)7245 2562sa 257251 222 179

a-C))

Appendix Ct CALCULATED -DATA ( Ocntinued)

1-6middot1 1023 o$2 14-41 26S 505 41~6 26~

54middot5 13middot3l-6-2 1201 067 1boo 625 47-9 17shy~middot41-6bull3 1296 oA9 1 middot43 26 9 700 so5 20bull 4 l-6-4 l3j5 o 0 19~09 268 71bull3 A5o 514 222 1-6-5 1) 5 o81 19(gt4 271 725 51-5 238 l-66 1398 081 198) 27-0 736 8 S13 252~-middot l-6j 1405 083 199i 211 733 885 $middot06 2$9 l-6 13middot9~ 103 2amp 0 279 71 8 985~ 467 ~-69 1228 1 bull 02 17-SS 270 661 109$ 407 ~3~ l-6bull10 1025 100 lSll 26i 573 1175middot 27~S32middot~l-ampu 153 1-00 llft3 26 444 1270 22 24bull8 1bull6-12 294 100 52a 231 22 3 1360 95 172

1-9bull1 904 048 1275 2J4Z $28 S4$ 459 1$2 1-92 98$ oss 13-92 24middot4 57-0 6JO 49bull1 176 1-9middot3 1110 066 1$76 24middot9 63middot4 I2o 536 21-7 l--9-4 1187 072 1685 251 66$ 5 $$ bull 0 261 1middot9-5 llltJ7 1710 25middot4 67-3 93$ 536 28~20-671middot9-6 1186 o 8 1708 25-7 67) 980 $15 2691-9- 1161 oBo 1660 2$middot3 6$6 990 508 29-1 l~- ll-32 oB) 16sect0 2$8 632 1030 471 291 1-9bull9 109$ oa5 2$7 614 1075 29S~middot 0 4imiddot41-9-10 9~91 oas 262 S$1 1150~ 3 o 292 1-9-11 o9o u57 12JiO 21gt 26-77middot74

-45 26sect ~middot91-912 $69 091 sas 25 middot3 1)0$ 196 2J-8 1-9-1) 220 098 426 2)9 178 1390middot 84 16 6

0 0

Appendx C CALCULATED DATA (Continued)

Turbine Run Generator Generator lurbine Turbine Eft1e1eney Turbine lurbine Spee1f1c

Number Output Losses Outit Input Speed Output SPed middot k_-V KW R _ H_bull_P Percent r Thm HP rpm_ (9) tlo) 11) middot (12 _) (lJI ( ) (1$ (14)

2-9-1 9--46 055 1)62 258 528 580 164 2-9-2 1024 056 248 58 4 665 4 9 191iimiddot48 4~middot0 2-9-3 1132 067 05 2$0 641 795 52q 237 2-9-4 1148 065 1027 2$1 -~8 845 525 252 2-9-5 11 77 oso 16-83 253 6 910~ 522 270 2-9 6 1122 071 1600 251 622 960 47-5 2722-9-A 1092 015 1562 257 608 1010 445 2z12bull9- 1052 079 1514 261 580 1060 41middot7 2 2 2middot9-9 986 o82 ]429 26) 542 1105 372 277 2-9-10 915 086 1340 268 500 1160 334 27-6 2-9-11 638 087 972 254 )81 1270~ 229 250 2-9-12 )28 090 828 259 )19 1295 179 226 2-9-13 192 094 383 2$ 6 150 1370 7 3 152

-3 0

Page 25: The Effect of A Variable Draft Tube Flow Area on the

18

draft tttbe tor supplampment1ng control or the rate ot rlow

Let it also be assumed that the two turbines are opershy

ating at the same point It 1s desirable to predict relabull

tive performance of the two turbines 1 this point of

operation is such that edd7 s hook loss ot reasonable proshy

portions is present in the fir t turbine

~ tull erteot of the shock loss will be exper1 need

by- the fir t turbine

lhe second turbine will derive certain advantages 11

the gate in the draft tube is adjusted to reduce the tlov

1n the proper amount Since they vary a the square ot

the veloo1t7bull the lossabull in the aeroll case wiomiddotket gate

and runner passages will decx-ease aetet-r1ng to Figure 2 1

it can be seen that a decreased velocity v1 w-ill reduce the

eddy shock losa

The ent loss in the dJtaft tube of the second turbine

will be the sum ot the tr1ct1onal loss and the velocity

head at ex1t The velocity head dissipated will be greater

due to the closing action or the gate but the reduoed

t~ictional loss which ia a tunction ot the rate of tlow1

will partially balance this

It 1a entirely possible that the net reduction in

losses in the second turbine will lead to a greater ettibull

oiency and more power output than 4eYeloped by the first

turbine

19

In Figure 3 the plot ot power output against turbine

speed for Curv A~ represents the typical family of curvea

tor a reaction turbine Th b st sp ed is the locus ot

points connecting maximum eft1oiency at each gate opening

The operating speed is the coZUJtant turbine apeed which

passes through the point ot maximum efC1ciencr of the turbull

bine The plot of turbine efficiency against power output

for Curve A is also ahown

It the turbine with flow regulation in the dratt tube

oan demonstrate superior power and efficiency at part loads

the effect would be the same as a shifting or the power

curves toward the condition shown fop Curve B 11 Thisbull

illustrates th ultimate case of the uperpoait1on of best

and operating speeds It will be noted that the pet-form~

of the turbine ot Ourve Bu 1a better than that of CUrve

A at part loads because of ita ability to sustain a relabull

tively high etticienoy ovel a Wider range of power output

o Reguireaegts tort Test Velitication

It is desired to deterra1ne the effect on the turbine

performance b) the addition of a gate in the dratt tube

Th step in the teit will bet

(1 To determine the power output and efficiency ot

the turbine tor wicket gate settings above and below rated

conditione for a wide range ot speed

20

CURVEAbull

TURBINE SPSBD TURBID SPEKD

POIBR OOTPOl

Figure 3 - Turbine Performance Curves

21

22

(2 peat (l) with the gate installed in the drat

tube

(3) middot Converting middot all data to a constant head compare the

powere and effioiencies at the same wicket gate setting and

turbin speed tor the two cbullses

If the ddition or the gate indicates an improvement

in power output and efficiency and the powe~ curve shifts

to the right along the turbine apeed scale the advantage

ot draft tube con~ol of the flow will hav been demonshy

strated

Chapter IV

A E9J11pment

ih turbine used in this test is lJ 5 1nch Pelton

reaction turbine with a rated output ot 30 horsepower under

a head of 56 feet at a speed ot 720 reYolutiona per minute

Views of this turbine are hovn in Figures S and 6 The

turbine is installed on a concrete pad located over an open

channel in the Hydraulics Laboratory at Oregon State Colshy

lege The date of manufacture of this turbine was 1915

The water was delivered to the turbine from a sump

reservoir by two pumps operating 1n parallel Each pump 1a

an 8 inch Pelton double suction centrifugal pump witb a

rating of l$00 gallons per minute at a head ot 75 teet with

a speed ot 1175 revolutions per minute Tbe inlet tlange

ot tne turbine is $pprox1mately 18 feet above the center

line of the pump

A direct current generator was coupled to the turbine

to receive tne power d veloped as shown in Figures 4 and 7 The generator is a Spr gue Electrodynamometer rated at SS horsepower with a speed range of 7$0 to l$00 revolut1one

per minute The classification is type LO 26A 2)0 volta

Figure 5 - View of Test Turbine

Figure 6 ~ View of Test Turbine

and 149 amperes lbe generator ti ld was aepar tely

excited using direct current from a motor g n r tor ampt

(l$ p 4~8)

The power output of the generator waa dissipated in

the water rheostat (3 p 488-489) shown in Figures 9 and

10 The galvanized tank contain d water ot variable d pth

on an electrode ot cast iron m aauring 1bull x 1 x 1

In the initial installation of the turbine it was

intended that the power output should be measured with a

Prony brak bull For th purpoa68 or this teat it was decided

that the brake was too instable and the generator was

substituted The platform for raising the generator the

nee asary two teet for alignment was built out of available

material In this case heavy laminated wood blocks reiashy

torced with other timbers were used and bolted through the

concrete deck (11 Pbull 36-$7)

Due to the light concrete deck the lack ot mas in

the platform and the slight misalignment in the flexible

coupling ao e vibration waa encountered It seemed to

ncr aae linearly to a maximum at the speed of bout 750

revolutions per minute Above this speed no vibPation was

noticeable The vibration waa not se~ere and does not

appear to have materially affected the test results

26

B Intrumentat1on ~ eaeur1ng Devices

The pressure head at inlet to the turbine vaa meaave4

bymeane ot two )6 inch waterbullmeroury manometerbull connected

in series as shown in Figure 8

The terminal voltage ot the generator vas meaeured by

a laboratory voltDleter with a range to )00 yolta and callbull

brated to within 15 Yolta

The armature current bull and hence the line current was

measured by a laboratory ammeter with a range to 150 amperea

and callbrated to w1 thin o 7S amperes

Tae rate ot tlow was established by weight and time

meaeurementa The weighing ank has a capacity ot 121 000

poundsJ the weight belng indicated by Toledo direct reading

scales Timing was done with a hand atop watch with clivibull

aion ot 02 second

he ~ater level in the tailrace was dete~1ned by a

hook gauge lhie was read to the nearest 001 toot

The turbine and generator speeds were eaaured by a

hand tachometer The technique of almost cont1nuoua readbull

ings of the speed gave an error ot no more than 5 revolubull

tiona per minute

c Operational Procedure

Atter the water level in the aump was checked to

insure an adequate auppl7 the puapa were primed and

27

Figure 7 - Test Generator and Plattorm

Figure middot8- Instrument Board and Field Rheostat

28

started After venting they were valved for operation 1n

parallel

The motor generator set was started to supply the

field current and the circuit breaker was closed Water

wa added to the water rheostat to the level shown in

Figure 10 ~ field current wae minimized by cutting in

all the f ield resistance in the field rheostat of Figure 8

The l2 inch gate valve shown in Figures 5 and 6 waa

slowly opened and the turbine and generator brought up to

speed The 12 inch gat valve and turbine were vented and

the pumps were checked to insure neither had lost ita prime

lhe water rheostat offers very steady load 1f the

water level is essentially constant and the water temperabull

ture 1a fixed () p 488~89) In order to maintain this

constant temperature it was decided not to circulate the

water in the rheostat but rather to allow the water to

boil thua achieving the desired result A standing wave

was set up on the face ot the electrode by the boiling

action but a atable load was eatablished except at very

low water leYels where th11 agitation led to fluctuationa

in the line current

After putting the turbine and generator on the line

maximum power was dissipated in the rheostat by redueing

the turbine speed to between oSO and Soo revolutions per

minute Salt vas added to the rheoetat wat r to increasemiddot

29

Figure 9 - View of Water Rheostat

Figure 10 - View of Water Rheostat

Separate Field ExcitationFrom Motor-Generator set Compound Water-Mercury

---shy

re Manometer

I Q)

~ 0

~

Book Gauge

Open Channel

I

Slap Reservoir

Figure 11 - Wat~r Flow Diagram and Electrical Layout

31

waiting pe~iod ot perhaps an h~ followed

while the boiling point or the water wbulls reacbe4 During

this ti+ne the manometer was vented end eheoked electrical

measur1ng 1nstlUments were connected end the hook gauge was

adjusted tor elevation

It required about two- houtte tor the generator to reach

its normal operating tempe-ratu~e_ After the water in the

rheostat and generator had reached their operating temperabull

turea it was possible to begin the taking of data

The only vaPiable which was controlled wee the turbineshy

generator speed However the upper l1ut1t of safe line

current was slightly over 100 ampJilPampPes and the eireuit

breaker would open when the current reached lOS ~ere bull

Control was exercised by means ot regulating the water

level and salt 1n the water rheo tat and the res1stsnoe of

the tield rheost t~

The etfeet ot each type ot regulation on the three

variables is shown below

Volta Aaperebull Speed

Inc Dec Inc Dee~ Inc Dec

Wa~e1 Level Inc Dec~ X

X X X X

X

Salt Concentration

Inc Dec X

X X X X

X

field Resistance

Inc Dec

X X

X X

X X

32

Jlot all methods gave the ame amount ot change in a

given variable and a period of experiment and trial led to

the following scheme starting the rune with the lowest

turbine speed the water level was high with a high amount

ot salt and the field resistance was cut completely out

Aa it became necessary to increase the speed tor each

aucceasive run either cutting in t he field resistance

decreasing the salt concentration or lowering the Vater

level would produce the desired result However decreasbull

1ng the salt concentration had to be done Without a net

gain in water which led to a tluahing procedure that was

not particularly good because cold water was introduced

which required time to heat to the boiling point Cutting

1n additional field resistance was a good method but th1a

increased the amperage possibly to the point of opening

the circuit breaker Lowering the water level was aatiashy

factol1 until the level got too low causing the current

fluctuation previously mentioned Actually it turned out

that a combination of lowering the water level and cutting

field resistance in would carry the speed from ita minimum

to 1ts maximum value it the proper choice were made each

time the speed waa to be changed At the conclusion of

each aet of runs at a high speed the water level would be

low and the field resistance high

33

TURBINE

PAD AND DECK

TAILRACE

WATER SURFACamp

CONCRETE

DRAFT TU1B INSERTS

7 5( DRAFr TUBE

FLltJI ARIA

5~ DRAFT TUBE

FLOI ARSA

Figure 12 - Sketch of Draft Tube and Test Inserts

34

Figure 13 - View of Draft Tube Insert

Figure 14 - View of Draft Tube Insert

D c __ ~s_middot hedu_le of

A number was assigned to each run The fi~st number

applies to the draft tube tlow areas

1 bull 100~ flow area or 0~ oonatriction

2 - 7S tlow area or 2$ conatr1ct1on

3 SoC flow area or so~ constriction

The second number refers to the wicket gate openings

9 over gate opening

6 bull intermediate gate opening

4 bull one h lt gate opening

The third number 14entif1ea the location of the particular

1Wl in a set ot rona made at a given dratt tube tlow area

and wicket gate opening

fnua run number 1bull4bull10 would identity this as the

tenth run ot a set made at halt gate with 75 ot the draft

tube t1ow area

Rune w re made tor a g1yen dratt tube condition

Firat tor tull 41-aft tube flow area seta ot rune were

made for the overgate halt gate and intermediate gate

conditione An insert was placed in t he draft tube and

rune based on the same gate conditions were made tor the

7S~ draft tube flow area case The insert was then changed

to allow only $~ draft tube flow area

The inserts are sketched 1n Figure 12 and photographed

ln Flgurea 13 and 14 They oonaisted of circula~ segments

36

or l2 ineh plywood mount 4 on wooden legs 10 inches high

The 1nse7te were placed in position and secured by th use

ot a-clamps on the legs and the outside ot the bottom of

the draft tube The obvious disadvantage to this method

waa the neoeasity tor draining the water from the tailrace

tor a change ot 1naert The advantage vas of course the

simplicity ot design and construction

Chapter V

DATA-A Original Data

The normal data-taking crew consisted or two men

Assuming adjustments having been made to secure a certain

turbine speed (aee section on Operational Procedure) one

man would take semi-continuous speed readings with the hand

tachometer until a state or rotational equilibrium was

reached This could be only a period or two minutes up to

ten or tifteen minutes As soon as steady speed was

assured the data taking would begin The second man went

to the weighing tank Where a minimum ot three weighingamp

were made The requirement was to get three consecutive

readings such that the ditterence between tbe smallest and

largest time did not exceed 04 seconds The time to

collect a given weight ot water was then assumed to be the

arithmetic average of the three times He then went to the

hook gauge determined the hook elevation and then

recorded the data on the data sheets The first man meanshy

while had taken readings of the line voltage line current

and manometers and checked the turbine speed by multiple

readings During the length of the run all values were

38

checked to determine mean values for recording

The minimum length of one run was about five minutes

If one or more measure ants tended to drift during the run

all values wer discarded and a new run began as soon aa

qu111br1um was stabl1shedo

B -0-al_e_u_l_a_t--d Data

The h d on the tu~bine 1 defined by

($)

The maxtmwm velocity V4 was equal to about o8 tampet per

secon4 which makes it a negligible quantity when converted

into velocity head

An engineerbulla level was used to deterine the d1ffePshy

ence 1n elevation between the compound water-mercury manoshy

meter and the hook gauge Using this value the equation

for turbine bead becomes

where z4 is the hook gauge reading

The rate of flow 1 cent

w weight or water collected average time to collect

The inlet velocity v1 vas calculated by dividing the

weight rate or flow by the specific weight of water and the

)9

area ot ~e inlet pipe This was equivalent to dividing

the weight rate of flow by 490 Then the power input to the turbine is equal to

WHpin rri

10 (6)

Also

(P ~ut) Turbine

(P out) + Generator

(P lost) Generator

The power output of the generator is simplJ the

produot ot the terminal voltage and the armature (line)

curPent The power lost in the generator can be subdivided

into copper losses and stray power losses lo evaluate

these cunes based on losses of an identical generator

11leampsured by the Department ot Mechanical Engineering were

used The loss curves are reppoduced in part in Figures

15 and 16

Determination ot generator losses proceeds as tollowau

(1) From Figure 15 detem1ne the vo1tage drop in the

armature circuit using the temperatures of 1220 F and the

meaaured current

(2) The induced voltage is t~e sum of the terminal

voltage and the voltage drop 1n the armature circuit

() Entering the induced voltage and the turbine speed

into Figure 16 the stray power loss can be determined

(4) The copper lose can be evaluated from Figure 1$

using the measured current and the temperatlll-e of 1220 P

40

25 ~------~--------~--------~------~

U) -U) - 20

f-4 ~

-~ -gt 0

0

VOLTAGE DROP

~ - i -

- bullbullbull bull - -middot-middot -+ ~- + -t--+ ~ - ~ middotbull ~-~ middott- -+----- _ -4 middotmiddot- --~-+-t---r~~ ~--+t-t- - ---t-c-++~-ulf--

0 50 75 100

Figure 15 - Curves of Generator Voltage Drop and Copper Loss

41

1200

1000

800

600

800

0

0

~-

middot--~ 1shy --1 + bull l

100

I -

150 200

IIDOOED VOLTAGB (VOLTS)

Figure 16 - Curves of Generator Stray Power Loss

_ j

-bullshy -L---- shy middot -shy

250

- r

42

(5) The generator los os equal the sum of the eopp r

loss and stray power loss

~e efficiency or the turbine is taken as

etticiency u e =P out (8)Pin

~ample pound Determ1n1gg turbine Power Output

The following data are taken trom that ot Run 1-9-1

Line voltage 1040 volts Line current 870 amperesSpeed 355 revolutions per minute

The induced voltage 1a determined as follows

Line voltage 1040

Voltage drop 90 using Figure 15 with line current of 870 amperes and temperature ot 122 degrees)

Induced Toltage 1130 volta

The power output of the turbine is determined as follows

Generator output 90$0 (line voltage z line current)

Oopper loss 7 (using Figure 15 with line current of 870 amperes and temperatUe or 122 degrees)

Stray power lose 470 (using Figure 16 with speed ot 355 revolutions per miDUte and induced voltage or 1130 volts)

Turbine power output 9527 vatta

or turbine power output 1s 12z2 horsepower

43

The conversion of the calculated data to a constant

head is based on the conventional assumption of constant

efficiency regardless of turbine head For a constant head

ot 81 teet a purely arbitrary figure the tollowing relashy

tionships are ass1lJiled to be true

I ____L (9) (i)l72

(10)

For these two values the specific a peed may be combull

putedt

N t Jt VPt (11)8 243

Chapter VI

~RESULTS

A -Pr_e_ae_n_t_a_t_t_o~n g Reaultbull

Graphical presentation ot the results ot this te1t

are given as follows

Figure 17 -Turbine characteristics with 100~ dratt

tuba 1low area

Figure 18 - Turbine characteristics with 7S dratt

tube tlow area

Figure 19 bull Comparison ot power and etticiency at

over gate conditions between 100 and

75~ draft tube flow area

Figure 20 bull COZQparison of power and ettic1ency at

halt gate conditions between 100~ and

7S~ draft tube flow area

Figure 21 bull Comparison of power and etticiency at

over gate condition between 100~ and

So dratt tube tlow area

Figure 22 - Comparison in variation ot apec1t1c

speed between 100 and 75~ dratt tube

tlow area

50

45

20

-bull - 1--shy40

bull J-~ 30

~ ex

~ 20

~~ ~ -)q

I

~ - _

- -

10~ OF DRAFT TUBE FL(Jif AREA

CONSTANT HEAD OF 8l FEST10

POIER OUTPUT EFFICIENCY SPECIFIC SPEED

0 ~--------------_--------~------~------~ 400 600 800 1000 1200 1400

TURBINE SPEED (RPM)

Figure 17 - Turbine Char~cteristics with 100 Draft Tube Flow Area

50

46

-bulllle

~ 7 ~ OF DRAFt TUBE FLOW AREA

0 -~~-rl C05STAMT BEAD OF 81 mET 1J~

POIER OOTPUT ---+- ---o ~_H EFFICIDCY ~ I shy

bull ql SPECIFIC SPEKD - ~ -

bull ~ J 10 L rmiddotr- r- -

bullz- I

~~ 30 ~~--~----~~-

20 ~ ~ middot-shy

26

~~ 25

~0 ~r-----i (

Tbull -bullshy

400 600 800 1000 1200 1400

TURBINE SPEED (R PK )

Figure 18 -Turbine Characteristics with 75 Draft Tube Flow Area

47

EFFICIENCY 60

1-----shy

-~ 50~--~--~~-~middot middot middot middot r~-~----~~~~---4~-r~-~~gtt

II

POWER~ J ~ bull bull

u I

sH

40~------+-------+---- -~~--~~-~~~~

~----~rl 1 bull

I

I

0~--------------~------_------~--------

~ -OVER GATE CONDITION

COIJSTANT HEAD OF 81 FEET

0 o 10~ DRAFt TUBE

_-- _ 7~ DRAFT TUBamp FLON AREA II

10_~-----+--------r-------r----~~

400 600 800 1000 1200 1400

TURBINE SPEED (RPM)

Figure 19 middot - Comparison between 75 and 100 Draft Tube Flow Areas of Power and Efficiency at Over Gate Conshydition

48

t

bull --4 r ~- ~ middot~

70 1-----------+-~~~~~+middot ~ ~~ middot middot -~~--~~--------~~----~-+1

-~-

Atbull bull

lla-

60

amp0

40

20

10

oampOO

t _ - - ~-+- - -~-

l2 GATB COJIDITIOJJ

COJISTABT HJW) OF 81 JBET

o 0 lOQ( DRAFl TUB8 FLOI AREA

e-- - e 75 DRAFT TUBE FLOW AREA

800 1000

- r-

~

TURBIbull SPBIID (RPII)

Figure 20 - Comparison between 75 and 100 Draft Tube Flow Areas of Power and Efficiency at Half Gate Conshydition

49

60

50

-40

bull 30

IIQbull

20

10

0

400

- t - ~

EFFICIENCY

_J bull - bull bull

~ r r middot t -+ shy L -t -

OVER GAD COliDITIOI

CONSTABT BEAD OF 8l FBB

o o 10~ DRAFt TUBE FLOI ADA middot--- 5~ DRAF TUBE FLQPi AREA

600 800 1000 1200

Figure 21 -Comparison between 50~ and 100~ Draft Tube Flow Areas of Power and Efficiency at Ove~ Gate Conshydition

50

25

20

15

10

0

Figure 22

~- T -4 -t- -l --~-

t-~ I

middot --~- t ~---- _ __ _ + --

----~- --r-- --

~-=J-~-=-~ -==~ _ ~- -- ---f---1 - shy

CONSTANT HEAD OF 81 FEBT

o--o 1~ DRAFT TUBE FLltll AREA

75C DRMT TUBK FLCIJ AREAmiddot--middot-middot 600 800 1000

TURBINE SPEED (RPK)

Comparison of Specific Speeds for 75 and 100 Draft Tube Flow Areas

51

B Discussion 2 Result

Consideration of Figures 17 and 18 indicates the

overall eftioi ncy pattern or hill is significantly or

rounded for the 7$~ flow area than for the 100~ flow area

bia implies a greateP efficiency is possible at speeds

leas than or greater than design speed with an insert in

the draft tube However the muilDum efficiency is lemiddotas

Direct comparison at over gate conditions is made in

Figure 19 ~e same general trend is noted tor both the

etticiency and power curves for the 7$~ flow area case

The eurves show higher values at overspeed than do the

correaponding cWvea for the 100 flow area case It ia

not clear whether the curves have been shifted by the dratt

tube constriction or whether the curves simply bulge past

the normal curves at both overspeed and underspeed condishy

tions The power curves apparently peak near the aeme

point bullalthough maximum power is still obtained with the

normal draft tube area

For the comparison at halt gate operation shown in

Figure 20 a general improvement has apparently been made

by restriction of the draft tube flow area At every speed

the etticienoy and the power is greater for the restricted

tlow case The two ett1o1ency curves and two power curvea

are practically parallel throughout the speed range ot

teat

As the flou aroa i e decreased still farther a s1gn1

ticant change appears Reterr1ng to Figllle 211 tor the $0

flow area curves it a obvious that exit losses have

become excessive at the overgate condition because the

efficiency and power are everywhere leas than tor the case

of normal draf t tube area

Earlier it was pointed out t hat 1t the r esult s 1nd1bull

eated an increase in both power and ef tieiency- t hen it

could be assumed tha t the additional los s i ntroduced with

the draft tube insert is less than the diminished losses

due to leas shock losa and water passage losses For the

places where both the efficiency and power have been

increased we can assume that the insert has improved turshy

bine performance

For the places where the power haa been decreased

nothing can be said as to the elimination of ampbock loss

because the new lose present with the drat tube insert has

overshadowed any gains in eftecti Ve head upatJ-eam of the

insert

Near the peak of the efficiency hill howeve~ it may

be pointed out t hat shock loaa ie a minimum with a normal

draft tube and the insert merely adds an additional loss

with the resultant decrease in maximum efficiency tor the

7$~ flow area case

Perhaps the most s1gn1ticant set of eurves is shown aa

53

Figure 22 In this graph values of specific speed tor the

75 and 100~ flow area cases for both over gate and one

halt gate openings are plotted against turbine speed At

every speed and both gate openings the value ot specific

speed for th 75~ flow area case is greater than that for

the 100 t1ow area ease

Since the head is a constant for both situations this

may be interpreted in either of two ways trom equation

(11)

(1) For the same turbine apeed restriction of the

draft tube t1ow area resulted in greater turbine power

(2) For the same power amputput the turbine with 75~

draft tube flow area operated at a greater speed than did

the one with 100 flow area

Since the required diameter of a turbine varies

inversely with the speed the second interpretation could

be stated such that a smaller turbine could be used to

develop the same power output

Whether viewed trom the aspect of increased power

greater speed or reduced size the performance of the turshy

bine with reduced draft tube flow area is superior to that

with the nolmal flow are in the draft tube

The curve of specmiddotific speed versus turbine speed for

the so draft tube flow area case at over gate cond1t1ona

was not included in Figure 22 This curve lies below that

for the 100~ flow area c se at all speeds

In elaboration ot the second interpretation of Figure

22 attention is directed to the relative magnitudes ot

increased apee1f1c speed tor the two gate openings Assumbull

ing that the increase in specific speed implies a shift ot

the power curve to the right along the turbine speed scale

the power curve would be shifted more tor tbe halt gate

opening than tor the over gate opening

It thia trend could be extrapolated to the other gate

openings the tendency can be seen tor the line ot beat

speed to rotate toward the line of the operating speed as

illustrated in FigtU-e ) The advantage of this has already

been discussed

This particular turbine has a low specific speed tor a

reaction turbine Aa the rated value of apecitic apeed tor

reaction turbines increases the line ot beat speed departs

even more radically from the line of operating bullpeed It a

test similar to this were conducted on a reaction turbine

ot gleater specific speed it is pJobable t hat the rotation

ot the line of beat apeed would become more p~onounced

The scheme used in th1a teat had two obvious dr wbull

backs The first was the decision to leave all the wicket

gamiddottes installed tor all conditions ot the draft tube

These gates predominated in control of the tlow The

inserts added to the draft tube merely acted as auxiliary

55

contrGla

The aecond drawback was the choice or device to place

in the draft tube The reasons foll selection of this type

of device have been previously mentioned It is to be

anticipated that adaptation ot dratt tube flow control

would result 1n a better device for an actual turbine

installation Such apparatus might take the form of a

pneumatic bladder or a h7drau11oally operated variable

venturi section in the draft tube It is conceivable that

the gate as used in this test might be adapted also

Chapter VII

OONCLtJSIOfS

From the results of this test the following eonolubull

e1ona aa to the effect ot a variable draft tube flow area

on the performance or a r action turbine may be drawn

(1) The effect ot a variable draft tube tlow area 1a

generally favorable upon the operat1Gn ot a reaction turbull

bine because or the tendency tor the line or beat speed to

rotate toward the line ot operation This resulte in

better performance of the turbine at partbullloads

(2) he etf1o1ency eh111 tor the turbine beeomaa JDore

tlat at the top leading to a smaller max1JilWD effic1enc7

but e reater etticieney at other pointe of operation with

the insertion ot an auxiliary control ror the rate ot tlov

in the draft tube

(3) The power output of the turbine will increase at

over speed over gate conditione as well a at part gate

conditions with the proper amount or draft tube eonatr1cbull

tion or flow

(4) It is possible to eliminate at least partially

eddy type shock loss by tho introduction ot flow control

in the draft tube

BIBLIOGRAPBl

1 Addison Herbert A treatise on applied h-draul1cs New York Wiley 1954 724 Pbull

2 Allen o M and I A Winter middot Co111parative testa on experimental draft tubes Tranaact1ons ot the American ociety ot Civil Engineers 87t893bull970 1924

3 Barrows a E Water power engineering 3d ed ew York McGraw-Bill 1943 791 Pbull

Bovet G A Modern trenda in hydraulic turbine design4middot in Europe Tranaactions of the American Society ot Mechanical Engineera 75975bull993 1953bull

s Oreager William P and Joel D Justin Hydroelectrichandbook 2d ed New York Wiley 19$0 1151 Pbull

6 Daily Jamea w Hydraulic machinery Int Hunter Rouses Engineering hydraulics Hew York Wiley 19$0 p 8$8bull99

Daughertybull Robert L Bydraulie turbines ew Yorkbull7middot MoGrav-Hlll 1920 281 Pbull

8 Daugherty Robert L Inveat1gat1on of tne performance ot a reaction turbine ~anaactiona or the American Society ot Civil Engineers 7811270bull1304 1915

9 Davie L M Model and prototype testa Int Trend in hydraulle turbine practice symposium lranaactions ot the American Society ot Civil Engineers 1o63S3middot368 1941

lfJ Doland James J Hydro power engineering Hew Yorkbull Ronald 1954 209 Pbull

11 Gandy Theodore s and Elmer c Schacht Direct curshyrent motor and generator troubles operation and repair New York McGraw-Bill 1911 293 Pbull

12 Gibaon Arnold H Hydraulics and ita applications5th ed London Constable 1952 813 Pbull

58

13 Button s P Component loases in Kaplan turbinebull and The prediction of efficiency from model tests Probull coedings of the Institution or Mechanical Engineers168743-762 1954

14 Knapp R T~ Oavit t1on mechanics and its relation to the d sign or hydraulic equip ent Proceedings or tne Institution ot Mechanical Engineers 166150bull16) 1952

15 Langsdorf Alexander s Principles of direct curHnt mach1nee 5th ed New York r~cGrawbullH1ll 1940 746 Pbull

16 Lsrner Chester w Characteristica of modern hydraubull lie turbines Trans e~ions of the ~~erican Society ot Civil Engineers 66306-386 1910

17 Linsley Ray K Jr and Jobulleph B Franzin1 Eleshyments of hydraulic enginebullring New York McGrawshyBill 19$5 $82 Pbull

18 Mead Daniel w Hydraulic machinery llev York McGraw-Hill 1933 396 Pbull

19 ead Daniel w Water power engineering New York McGrawbullRill 191S 843 Pbull

20 Mockmore Charles A Part gate operation at water turbines Corvallis Oregon State College Department ot Civil Engineering 1933 11 numb leaves (Unpubshylshed typescript)

21 Mockmore Oharles A Flow characteristics in elbow dratt tubes Transactions of the Amez-ican Society ot Civil Engineers 103402middot464bull 1938

22 Moody L F Hydraulic machinery In c v Davis Handbook ot applied hydraulics New York McGrawshyHlll 1942 1082 Pbull

2) Ptau At-nold Hydrbullulie turbine handbook ld ed Milwaukee AllisbullOhalmers ManufactUIing Company 1948 70 Pbull

RheingalUI w J Recent developments in Francis turshybines Mechanical Engineering 74189-196 1952

25 Russell George E Hydraulica 5th ed New York Henry Holt 1942 466 Pbull

26 Safford A and E P- Hamilton American mixed tlow turbine and ita setting Tranampactions or the Amerieal Society of Civil Engineers 851237bull1)56 1922

27 bull Spannhake W1lhe1Dh Problems or modern pump and tur b1ne design Transactions of the American Society of Mechanical Engineers 56e22$-248 1934bull

28 Sutherlandraquo R A Better ethod or representing and middot tudying water turbine performance ~ansaetions ot thmiddote American Society of Mechanical Engineers 68t675bull 686 1946

29 Teats ot five models or draft tubes tor turbines Engineering News-Record Pbull 182-184 Aug 2 1923

30 White w M American hydztaulic turbines Mechanical Engineering S2t390bull39S 1930bull

31 White w M lhe hydraucGne rega1ner1 its developmentand appl1eat1ons 1n hydroelectric plants Meohanlobulll Engineering 43t37Sbull380 1921 middot

32 Winter I A Economic principlebull in designbull Int Trend in hydraulic urbin practice bull a ampoeiumTranaaot1ona ot the American Society ot Civil Engineerslo6332bull3S2 1941

33 Wiel1cenua G F Fluid mechan1ca or turbo-machineryNev York McGraw-Hill 1947 613 Pbull

APPENDICES

c

Appendix A

NOATIOB

A Angle between the absolute velocity vector and the tangent to the rwmer Subscripts 1 and 2 refel to entrance and exit ot the runner blade

B Angle between the relative 1elooity vector and the tangent to the rwmer Subscripta 1 and 2 refer to entrance and ezit or the runner blade

Angle between the tangent to the runner blade tip and the tangent to the runnel- Subscripts 1 and 2 reter to entrance and exit of the rt1rmer bladebull

Blade angle-gate opening conetant defined by equation (1)

e 09erall efficiency

g Gravitational acceleration assumed constant at 322 teet per second per second bull

H Turbine head detined by equation ($)

m Exit loss coeft1e1ent

Turbine speed expressed in revolutions per minute

Turbine speed under a constant head of 81 teet

specitic apeed of the turbine under a constant head ot 81 teet

p Power output in horsepower ot the tvbine

Power output of the turbine Ulder a constant head ot Sl teet

Pl- Pressure head at entrance to the tUlb1new

l1 Peripheral velocity ot the runneP Subacr1pta 1 and 2 refer to entrance and exit ot the JUnllampr blade

62

v Relative velocity reaulting trom the combination ot the absolute water velocity V and the runner periphshyeral velocity u Subscripts 1 and 2 refer to entrance and exit ot the runner blade

v] Relative velocity vector necessary to produce a tanbull gential entry into the runner blades

V Absolute water velocity Subscripts l and 2 refer to entrano and exit ot the runner blade

v2 Velocity head Subscripts 1 and 4 reter to the ~8 entrance to the turbine and the tail~ace wate~

w Unit weight ot water assumed constant at 624 pounda per cubic toot

V Weight rate ot flow in pounds per aeooncl

XX Velocity component ot ahook See Figule 2

Z Elevation head Subscripts 1 and 4 reter to entrance to the turbine and the taibace water surfacebull

Appendix B ORIGINAL DATA-Run

lfwnber

0-4-1 0-4-2 0-4-3 o-4-4 o-4-S o-4-6 0-4-7 0-4-8 0-4-9o-4-lo o-4-11 o-4-12 0-4-13

o-6-1 o-6-2 06-3 o-6-4o-6middotS o-6-6 o-6-7 o-6-8 0-6-9 o--6-lo o-6-11

Speed

rmiddot2middotbullmiddot(1)

336 38$ 451 S$9 620 669 6lt)$ 120 787 860 932

102imiddot109 bull

352 355 443middot 543middot 620 654AJs32

911 1001 1111

~essure Head rt (2)

410 410 416 426 431 43-7 439 44-9 452 467 482 soo $1 bull $

350 351 35middot7 )66 37-9 37-9 392 41 bull 3 43middot3 460 489

Elevation Bead

fjj $7 $7 $7 $7 $7 $7 51 57 5-15858 $8 58 56 56 $6565656 51 575As5a

Velocit Head

flj 07 07 07 06 06 06 06 os 05 os0404 03

09 09 oa o8 o8 os 07 07 06 o~o

Total Head rt ($)

47middot4 4A44 o 489 49-4 soo $02 $11 $14 $29 5imiddot45 2 576

41 bull $ 416 421 430 44middot3 44middot3 456 47-7 496 523551

Plow

lbtjec

326 324middot317 311 306 30029middot28 middotmiddot middot 386 275middot260 240 218

359 36~35 bull 349 345middot 339 330 318 300 273 240

Line Potential

vyqjbull 1060 1220 ~-0o 1920 2150 2000 2$60 2000 1940 18)015io11 o

1000 1100 139bull5 1760 1925 16$0 1620 1610 1540 1330 870

Line Current

amlscs 960 900 830 740 730655 70bull 0 530 660 600 5imiddot54 6 )60

982 930 860 780 ~3-545

79-5 74-5 670 560 370

P

Appendix B ORIGINAL DATA (Continued)

Run Number

Speed

Pbulltmiddotbullmiddot )

leasure Head ft(2

Elevation Head tt(J)

Velocity He-dfmiddotj

Total Bead tt($

Flow

lbstsec( )

Line Potential vo~ta( )

Line Current

amjs (sect

0bulllt)-1 0-9-2

3ll6 398

28o ~~1

$6 56

1o 10

346 347

390 365

1ooo 1190

aao 835

0-9-3 0-9-4 o-9-S

472 565 632

292 305 312

$6 s6 56

10 o9 o9

)$8 J7~o 37~7

381376 37o

1)6614oo 141o

820 ass ass o-9-6 0-9-7 0-9-8 o-9-9 0middot9-10

680 120 762 844 920

)24337346 366 390

56 $6 56 57 $7

09 os o8 oa 07

)89401 410 431454

367~ 357348 34o 322

1400 1J6o l36o 1310 1170

843 820 7957So 67~0

0-9-ll 0-912

1001 1100

41 bull 7 45-3

s 7 6~0

06 os 480 $18

299 268

980 65$

560 36~5

1-4-1 1-4-21-4-l1-4shy1-4-5 1-4-6 l-4-7 1 4-8 1-4-9 1-4-10 1middot4-ll 1-4bull12

354middot452 562 62q 674shy102 752 760- 863 932

1022 1100-

)82389 4014oa 416 41--7 423 428 44-2 45-7 486 49-2

51S757 51 5-7 5middot15zs sa $8 58 59

07 07 06 06 06 06 06 os o bull o 04 o J

446 45-)46middot4 471 ti7-9480 q86 491505 $19 548 55-4

)28 320 311 306 300 295 291 286 269 2582iimiddot21 bull

1080 14Lo 1550 153-5 1470 141-0 1385 1310 1310 1230 1120 855

970855 875 91-0 94~0 975 966 995 860 77-S 610 4fo

0 ~

Appendix B ORIGINAL DATA (Contirmed)-Run Speed Pressure Elevation Velocity Total Flow Line Line

Number Head Head Head had Potential Current rtjjmbull t~ bttec vyfs am~a12) ( ) ti fli 8

1-6-l $6 33$ $6 0bull9 400 364 1100 93 0 1-6-2 41 34laquo2 $6 oa 406 JS7middot iios a5s l-6-3 500 3~0 5bull6 os 356 1 1 o aos 41middot~1-6~4 35bull4 5-6 oa 41middot 352 16~0 82 0 5~1-6-5 5 bull 36_2 Sbull6 08 42bull6 349middot 161 ~ 0 86~0 1-6-6 622 366 $6 oe 43bull0 345middot 158 0 88~$ 16-A 649bull 37bull1 56 os 43-S 342middot 1570 895 1~- 386 57 07 46-0 192 ) 125A44 333middot 1-6-9 3) 404 5middot1 07 468 317 1620 675 1610 911 42-4 5-7 o6 48-7 298 168 0 61 0 1-6-11 999 451 56 os Sl ll 276 ~2-0 530 1-612 1115 485 58 04 54middot7 238 90 )3 0

1middot9-l 355 279 56 10 )45 385 1040 870 1-9-2 399 28J $6 10 )49 38$ 1140 86 5 l-9-3 ~ ao 291 56 ~0 35middot1 J8J_ JJ6o 815 1bull9-4 579 303 56 09 )68 375middot J4JO 830 l-9bullS 40- 313 )6 09 31middot8 370- 1460 82~0 1-9bull6 679 2) 56 09 3 bull8 364middot 1670 710 l-9-7 682 319 56 o9 384 ) 62 1460 79 5 l-9-8 724 33middot5 56 o8 399 3$6 bull 1480 76 -5 1-9-9 762 34middot3 $6 0 bull 8 407 )48 14910 13middotS 1-9-10 833middot )60 5middot7 os 42$ 339 144$ 686 1-9-ll 926 39middot1 5-7 07 455 318 1290 600 1-9-12 1000 41middot3 0-6 476 298 1115 510$ ~ 1middot9-13 1105 452 s o4 $14 2$6 710 )10

~

Appendix Bt ORIGDIAL J (Continued)

Run Speed Pressure Elevation Velocity Total Plow Line Line Number Head ltead Head jlamp$d P()ten~ibulll Current

r~~~m ft ft lbs~seo voltattj rgj twimiddot t 1 t2gt lt3 ou t ( rt

2-9-1 384 289 S 6 10 35 5 1400 1170 810 2-9-2 443middot 29$ $6 ltimiddot9 360 379middot 11(0 87$ 2-9-J 536 30bull 3 sc 09 )68 374middot 1)40 84 bull) 2-9-4 571 306 $6 09 3~1 372 120bull 0 955 2-9-5 623 316 S6 09 J l )6S UJSo 77$ 2bull9-6 669 327 S6 09 )92 )61 1240 905 2-9bull7 712 )39 56 os 40-3 351 12(0 86 bull0 2-9-8 ~5$~ J48 56 oa 412 348 1290 81 bull ) 2-9-9 04 )63 56 oa 42-7 339 12ltJO 76$ 2middotmiddot9-10 8$2 376 5middot1 07 440 33~- ~ o 710 2-9-11 955 394 5-1 o6 457 300 1100 506 2middot9-12 1000 421 $7 06 48middoti 295 1020 $18 2-9bull13 110~ 463 56 05 $2 267 620 3~0

oshy0

Appendix Gt CALCULATED DAgA

Turbine Run Generator Generator Turbine Turbine Efficiency Turbine Turbine Specit1c

Number OutputKWlt21

Loa~Jes KWlol

Outut K bull (H)

Input RP 12)

middot Percentlt13gt

Speed r~Jmiddot(

0ltput HP ~1

Speed r-m

( 6) middot

o-4-1 0middot4-2 0-4-3 0-4-4 0-4-5 0-4-6 O-qmiddot7o-4-8o-4-9 0-4bull10 0-4-11 o-4-12

1018 1o9a 1220 1)62J40214oa1J4oo 1357 1320 1164 997 718

046 o59 071 092 096 1071oo 134 104 100 109 107

14261sso 17)01948 2008 20322011 1999 19 09 1708 14-84 11o6

281279 27-7 276 215 273271 268 268 26h 258 24-5

soa 555 62$ 705 7)1145 742 74-6714645 51s 45-1

440 sos 585 720 195 sso sao 9$$ 985

1065 1135middot 1230

318 357 319 416 422 419412 39middot9 378 324 260 191

102 12bull4 148 191 21bull 3 22o 233 249 24924middot9 238 221

0-4middot13 418 104 699 228 306 1300 117 18)

o-6-1 982 045 1376 271 $08 496 376 124 o-6-2 o-6-3 G-6-4o-6-5 0-6-6

1023 1200 13 73 J415 139h

051 0middot66 oaa ()bull 96 088

14-39 1696 1958 2026 1986

276 27middot4 273 278 274

$20 61 8 717 7)0726

q95615745 8)5685

390 ll5middot3 sos soo 490

127 170 218 243 2$$

o-6-7 o-6-8 o-6-9o-6-lo

1288 1199 1032 7-45

o9o 094 09$ 096

1846 1733 1511 1128

274 276 271 260

67S 629559 43middot4

980 1085 1165 1245shy

436 )83316 21bull 7

266 276 270 239

0-6-11 322 1oo 566 2141 2JS 1350 101 177 0 --4

Appendix C CALCULATED DAlA ( Continued)-Run

Number Generator Generator

Out2ut Losaes xw LW- 12gt (lO)

Turbine Out2ut

ltPlJ

Turbine Inat lfP Jig)

Etpound1e1ency

PireentDl

Turbine Sed x-~m( 1

Turbine OutEut RPJl)

Turbine Specific

SeeedrIbullntbull

( 6)

o-9middot1 0-9-2 0-9-3 o-lt)-4 09-$ 0bull9-6 0-9-7 0-9-8 0-9-9 0-9-10 o-9-11 0-9-12

aao 994

111$ 1197 1206 1180 11)21081 982 784 5-49 2)9

0middot45oss o6$ 070 07$ 0-77 (l77 or~ o s06o 8 096

123~ 1402 1$80 1698 17bulllS 168$ 16bull18 ~middot5430 1151 a~J4 9

24middotgt24middot3248 25~25 260 260 259 267 266 26middot1 2S2

sos 577 63-7 671 676 650 621 60036J4

327 178

$) 610AlO 3$

92S 980

102$ 1070 1157middot 1230 1300 137Smiddot

44middot4 soo 523 ssomiddot 540so6 46-5 432 368 274 18~8

J46 176 21-1 255 2802s_A 28 289 288 265 231 168

1-4-1 1-4middot2 1-4-3 1-4-4 1-4-5 1-4-6 1-4-7 1-J-8 1-4~9 1-4-10 1-4-11 1-4-12

10bull48 1231 13-S6 1397 1)821375 1))8 1303 1127 953 683) 51

048 067 o7A07 0 bull79 oa1 oss o bullao osa 0lt)0 096 099

J468 1740 1921 1978 1958 19$1 1911 lSSi162 1)98 1045

603

266 264 262 262 261 2512$7 2$6 24middot7 24-3 233 217

551 660 13middot3155 75-6 7~-97 middot4 72$ 67 51middotJ 44middot9 21middot1

475 605 A4220

875middot 910 970_

1000 1090bull 1166 1243 1330

5816

44middot444middot5 430 427 412 392 329 273 188 l0-7

117 101 204 22$ 2)7245 2562sa 257251 222 179

a-C))

Appendix Ct CALCULATED -DATA ( Ocntinued)

1-6middot1 1023 o$2 14-41 26S 505 41~6 26~

54middot5 13middot3l-6-2 1201 067 1boo 625 47-9 17shy~middot41-6bull3 1296 oA9 1 middot43 26 9 700 so5 20bull 4 l-6-4 l3j5 o 0 19~09 268 71bull3 A5o 514 222 1-6-5 1) 5 o81 19(gt4 271 725 51-5 238 l-66 1398 081 198) 27-0 736 8 S13 252~-middot l-6j 1405 083 199i 211 733 885 $middot06 2$9 l-6 13middot9~ 103 2amp 0 279 71 8 985~ 467 ~-69 1228 1 bull 02 17-SS 270 661 109$ 407 ~3~ l-6bull10 1025 100 lSll 26i 573 1175middot 27~S32middot~l-ampu 153 1-00 llft3 26 444 1270 22 24bull8 1bull6-12 294 100 52a 231 22 3 1360 95 172

1-9bull1 904 048 1275 2J4Z $28 S4$ 459 1$2 1-92 98$ oss 13-92 24middot4 57-0 6JO 49bull1 176 1-9middot3 1110 066 1$76 24middot9 63middot4 I2o 536 21-7 l--9-4 1187 072 1685 251 66$ 5 $$ bull 0 261 1middot9-5 llltJ7 1710 25middot4 67-3 93$ 536 28~20-671middot9-6 1186 o 8 1708 25-7 67) 980 $15 2691-9- 1161 oBo 1660 2$middot3 6$6 990 508 29-1 l~- ll-32 oB) 16sect0 2$8 632 1030 471 291 1-9bull9 109$ oa5 2$7 614 1075 29S~middot 0 4imiddot41-9-10 9~91 oas 262 S$1 1150~ 3 o 292 1-9-11 o9o u57 12JiO 21gt 26-77middot74

-45 26sect ~middot91-912 $69 091 sas 25 middot3 1)0$ 196 2J-8 1-9-1) 220 098 426 2)9 178 1390middot 84 16 6

0 0

Appendx C CALCULATED DATA (Continued)

Turbine Run Generator Generator lurbine Turbine Eft1e1eney Turbine lurbine Spee1f1c

Number Output Losses Outit Input Speed Output SPed middot k_-V KW R _ H_bull_P Percent r Thm HP rpm_ (9) tlo) 11) middot (12 _) (lJI ( ) (1$ (14)

2-9-1 9--46 055 1)62 258 528 580 164 2-9-2 1024 056 248 58 4 665 4 9 191iimiddot48 4~middot0 2-9-3 1132 067 05 2$0 641 795 52q 237 2-9-4 1148 065 1027 2$1 -~8 845 525 252 2-9-5 11 77 oso 16-83 253 6 910~ 522 270 2-9 6 1122 071 1600 251 622 960 47-5 2722-9-A 1092 015 1562 257 608 1010 445 2z12bull9- 1052 079 1514 261 580 1060 41middot7 2 2 2middot9-9 986 o82 ]429 26) 542 1105 372 277 2-9-10 915 086 1340 268 500 1160 334 27-6 2-9-11 638 087 972 254 )81 1270~ 229 250 2-9-12 )28 090 828 259 )19 1295 179 226 2-9-13 192 094 383 2$ 6 150 1370 7 3 152

-3 0

Page 26: The Effect of A Variable Draft Tube Flow Area on the

19

In Figure 3 the plot ot power output against turbine

speed for Curv A~ represents the typical family of curvea

tor a reaction turbine Th b st sp ed is the locus ot

points connecting maximum eft1oiency at each gate opening

The operating speed is the coZUJtant turbine apeed which

passes through the point ot maximum efC1ciencr of the turbull

bine The plot of turbine efficiency against power output

for Curve A is also ahown

It the turbine with flow regulation in the dratt tube

oan demonstrate superior power and efficiency at part loads

the effect would be the same as a shifting or the power

curves toward the condition shown fop Curve B 11 Thisbull

illustrates th ultimate case of the uperpoait1on of best

and operating speeds It will be noted that the pet-form~

of the turbine ot Ourve Bu 1a better than that of CUrve

A at part loads because of ita ability to sustain a relabull

tively high etticienoy ovel a Wider range of power output

o Reguireaegts tort Test Velitication

It is desired to deterra1ne the effect on the turbine

performance b) the addition of a gate in the dratt tube

Th step in the teit will bet

(1 To determine the power output and efficiency ot

the turbine tor wicket gate settings above and below rated

conditione for a wide range ot speed

20

CURVEAbull

TURBINE SPSBD TURBID SPEKD

POIBR OOTPOl

Figure 3 - Turbine Performance Curves

21

22

(2 peat (l) with the gate installed in the drat

tube

(3) middot Converting middot all data to a constant head compare the

powere and effioiencies at the same wicket gate setting and

turbin speed tor the two cbullses

If the ddition or the gate indicates an improvement

in power output and efficiency and the powe~ curve shifts

to the right along the turbine apeed scale the advantage

ot draft tube con~ol of the flow will hav been demonshy

strated

Chapter IV

A E9J11pment

ih turbine used in this test is lJ 5 1nch Pelton

reaction turbine with a rated output ot 30 horsepower under

a head of 56 feet at a speed ot 720 reYolutiona per minute

Views of this turbine are hovn in Figures S and 6 The

turbine is installed on a concrete pad located over an open

channel in the Hydraulics Laboratory at Oregon State Colshy

lege The date of manufacture of this turbine was 1915

The water was delivered to the turbine from a sump

reservoir by two pumps operating 1n parallel Each pump 1a

an 8 inch Pelton double suction centrifugal pump witb a

rating of l$00 gallons per minute at a head ot 75 teet with

a speed ot 1175 revolutions per minute Tbe inlet tlange

ot tne turbine is $pprox1mately 18 feet above the center

line of the pump

A direct current generator was coupled to the turbine

to receive tne power d veloped as shown in Figures 4 and 7 The generator is a Spr gue Electrodynamometer rated at SS horsepower with a speed range of 7$0 to l$00 revolut1one

per minute The classification is type LO 26A 2)0 volta

Figure 5 - View of Test Turbine

Figure 6 ~ View of Test Turbine

and 149 amperes lbe generator ti ld was aepar tely

excited using direct current from a motor g n r tor ampt

(l$ p 4~8)

The power output of the generator waa dissipated in

the water rheostat (3 p 488-489) shown in Figures 9 and

10 The galvanized tank contain d water ot variable d pth

on an electrode ot cast iron m aauring 1bull x 1 x 1

In the initial installation of the turbine it was

intended that the power output should be measured with a

Prony brak bull For th purpoa68 or this teat it was decided

that the brake was too instable and the generator was

substituted The platform for raising the generator the

nee asary two teet for alignment was built out of available

material In this case heavy laminated wood blocks reiashy

torced with other timbers were used and bolted through the

concrete deck (11 Pbull 36-$7)

Due to the light concrete deck the lack ot mas in

the platform and the slight misalignment in the flexible

coupling ao e vibration waa encountered It seemed to

ncr aae linearly to a maximum at the speed of bout 750

revolutions per minute Above this speed no vibPation was

noticeable The vibration waa not se~ere and does not

appear to have materially affected the test results

26

B Intrumentat1on ~ eaeur1ng Devices

The pressure head at inlet to the turbine vaa meaave4

bymeane ot two )6 inch waterbullmeroury manometerbull connected

in series as shown in Figure 8

The terminal voltage ot the generator vas meaeured by

a laboratory voltDleter with a range to )00 yolta and callbull

brated to within 15 Yolta

The armature current bull and hence the line current was

measured by a laboratory ammeter with a range to 150 amperea

and callbrated to w1 thin o 7S amperes

Tae rate ot tlow was established by weight and time

meaeurementa The weighing ank has a capacity ot 121 000

poundsJ the weight belng indicated by Toledo direct reading

scales Timing was done with a hand atop watch with clivibull

aion ot 02 second

he ~ater level in the tailrace was dete~1ned by a

hook gauge lhie was read to the nearest 001 toot

The turbine and generator speeds were eaaured by a

hand tachometer The technique of almost cont1nuoua readbull

ings of the speed gave an error ot no more than 5 revolubull

tiona per minute

c Operational Procedure

Atter the water level in the aump was checked to

insure an adequate auppl7 the puapa were primed and

27

Figure 7 - Test Generator and Plattorm

Figure middot8- Instrument Board and Field Rheostat

28

started After venting they were valved for operation 1n

parallel

The motor generator set was started to supply the

field current and the circuit breaker was closed Water

wa added to the water rheostat to the level shown in

Figure 10 ~ field current wae minimized by cutting in

all the f ield resistance in the field rheostat of Figure 8

The l2 inch gate valve shown in Figures 5 and 6 waa

slowly opened and the turbine and generator brought up to

speed The 12 inch gat valve and turbine were vented and

the pumps were checked to insure neither had lost ita prime

lhe water rheostat offers very steady load 1f the

water level is essentially constant and the water temperabull

ture 1a fixed () p 488~89) In order to maintain this

constant temperature it was decided not to circulate the

water in the rheostat but rather to allow the water to

boil thua achieving the desired result A standing wave

was set up on the face ot the electrode by the boiling

action but a atable load was eatablished except at very

low water leYels where th11 agitation led to fluctuationa

in the line current

After putting the turbine and generator on the line

maximum power was dissipated in the rheostat by redueing

the turbine speed to between oSO and Soo revolutions per

minute Salt vas added to the rheoetat wat r to increasemiddot

29

Figure 9 - View of Water Rheostat

Figure 10 - View of Water Rheostat

Separate Field ExcitationFrom Motor-Generator set Compound Water-Mercury

---shy

re Manometer

I Q)

~ 0

~

Book Gauge

Open Channel

I

Slap Reservoir

Figure 11 - Wat~r Flow Diagram and Electrical Layout

31

waiting pe~iod ot perhaps an h~ followed

while the boiling point or the water wbulls reacbe4 During

this ti+ne the manometer was vented end eheoked electrical

measur1ng 1nstlUments were connected end the hook gauge was

adjusted tor elevation

It required about two- houtte tor the generator to reach

its normal operating tempe-ratu~e_ After the water in the

rheostat and generator had reached their operating temperabull

turea it was possible to begin the taking of data

The only vaPiable which was controlled wee the turbineshy

generator speed However the upper l1ut1t of safe line

current was slightly over 100 ampJilPampPes and the eireuit

breaker would open when the current reached lOS ~ere bull

Control was exercised by means ot regulating the water

level and salt 1n the water rheo tat and the res1stsnoe of

the tield rheost t~

The etfeet ot each type ot regulation on the three

variables is shown below

Volta Aaperebull Speed

Inc Dec Inc Dee~ Inc Dec

Wa~e1 Level Inc Dec~ X

X X X X

X

Salt Concentration

Inc Dec X

X X X X

X

field Resistance

Inc Dec

X X

X X

X X

32

Jlot all methods gave the ame amount ot change in a

given variable and a period of experiment and trial led to

the following scheme starting the rune with the lowest

turbine speed the water level was high with a high amount

ot salt and the field resistance was cut completely out

Aa it became necessary to increase the speed tor each

aucceasive run either cutting in t he field resistance

decreasing the salt concentration or lowering the Vater

level would produce the desired result However decreasbull

1ng the salt concentration had to be done Without a net

gain in water which led to a tluahing procedure that was

not particularly good because cold water was introduced

which required time to heat to the boiling point Cutting

1n additional field resistance was a good method but th1a

increased the amperage possibly to the point of opening

the circuit breaker Lowering the water level was aatiashy

factol1 until the level got too low causing the current

fluctuation previously mentioned Actually it turned out

that a combination of lowering the water level and cutting

field resistance in would carry the speed from ita minimum

to 1ts maximum value it the proper choice were made each

time the speed waa to be changed At the conclusion of

each aet of runs at a high speed the water level would be

low and the field resistance high

33

TURBINE

PAD AND DECK

TAILRACE

WATER SURFACamp

CONCRETE

DRAFT TU1B INSERTS

7 5( DRAFr TUBE

FLltJI ARIA

5~ DRAFT TUBE

FLOI ARSA

Figure 12 - Sketch of Draft Tube and Test Inserts

34

Figure 13 - View of Draft Tube Insert

Figure 14 - View of Draft Tube Insert

D c __ ~s_middot hedu_le of

A number was assigned to each run The fi~st number

applies to the draft tube tlow areas

1 bull 100~ flow area or 0~ oonatriction

2 - 7S tlow area or 2$ conatr1ct1on

3 SoC flow area or so~ constriction

The second number refers to the wicket gate openings

9 over gate opening

6 bull intermediate gate opening

4 bull one h lt gate opening

The third number 14entif1ea the location of the particular

1Wl in a set ot rona made at a given dratt tube tlow area

and wicket gate opening

fnua run number 1bull4bull10 would identity this as the

tenth run ot a set made at halt gate with 75 ot the draft

tube t1ow area

Rune w re made tor a g1yen dratt tube condition

Firat tor tull 41-aft tube flow area seta ot rune were

made for the overgate halt gate and intermediate gate

conditione An insert was placed in t he draft tube and

rune based on the same gate conditions were made tor the

7S~ draft tube flow area case The insert was then changed

to allow only $~ draft tube flow area

The inserts are sketched 1n Figure 12 and photographed

ln Flgurea 13 and 14 They oonaisted of circula~ segments

36

or l2 ineh plywood mount 4 on wooden legs 10 inches high

The 1nse7te were placed in position and secured by th use

ot a-clamps on the legs and the outside ot the bottom of

the draft tube The obvious disadvantage to this method

waa the neoeasity tor draining the water from the tailrace

tor a change ot 1naert The advantage vas of course the

simplicity ot design and construction

Chapter V

DATA-A Original Data

The normal data-taking crew consisted or two men

Assuming adjustments having been made to secure a certain

turbine speed (aee section on Operational Procedure) one

man would take semi-continuous speed readings with the hand

tachometer until a state or rotational equilibrium was

reached This could be only a period or two minutes up to

ten or tifteen minutes As soon as steady speed was

assured the data taking would begin The second man went

to the weighing tank Where a minimum ot three weighingamp

were made The requirement was to get three consecutive

readings such that the ditterence between tbe smallest and

largest time did not exceed 04 seconds The time to

collect a given weight ot water was then assumed to be the

arithmetic average of the three times He then went to the

hook gauge determined the hook elevation and then

recorded the data on the data sheets The first man meanshy

while had taken readings of the line voltage line current

and manometers and checked the turbine speed by multiple

readings During the length of the run all values were

38

checked to determine mean values for recording

The minimum length of one run was about five minutes

If one or more measure ants tended to drift during the run

all values wer discarded and a new run began as soon aa

qu111br1um was stabl1shedo

B -0-al_e_u_l_a_t--d Data

The h d on the tu~bine 1 defined by

($)

The maxtmwm velocity V4 was equal to about o8 tampet per

secon4 which makes it a negligible quantity when converted

into velocity head

An engineerbulla level was used to deterine the d1ffePshy

ence 1n elevation between the compound water-mercury manoshy

meter and the hook gauge Using this value the equation

for turbine bead becomes

where z4 is the hook gauge reading

The rate of flow 1 cent

w weight or water collected average time to collect

The inlet velocity v1 vas calculated by dividing the

weight rate or flow by the specific weight of water and the

)9

area ot ~e inlet pipe This was equivalent to dividing

the weight rate of flow by 490 Then the power input to the turbine is equal to

WHpin rri

10 (6)

Also

(P ~ut) Turbine

(P out) + Generator

(P lost) Generator

The power output of the generator is simplJ the

produot ot the terminal voltage and the armature (line)

curPent The power lost in the generator can be subdivided

into copper losses and stray power losses lo evaluate

these cunes based on losses of an identical generator

11leampsured by the Department ot Mechanical Engineering were

used The loss curves are reppoduced in part in Figures

15 and 16

Determination ot generator losses proceeds as tollowau

(1) From Figure 15 detem1ne the vo1tage drop in the

armature circuit using the temperatures of 1220 F and the

meaaured current

(2) The induced voltage is t~e sum of the terminal

voltage and the voltage drop 1n the armature circuit

() Entering the induced voltage and the turbine speed

into Figure 16 the stray power loss can be determined

(4) The copper lose can be evaluated from Figure 1$

using the measured current and the temperatlll-e of 1220 P

40

25 ~------~--------~--------~------~

U) -U) - 20

f-4 ~

-~ -gt 0

0

VOLTAGE DROP

~ - i -

- bullbullbull bull - -middot-middot -+ ~- + -t--+ ~ - ~ middotbull ~-~ middott- -+----- _ -4 middotmiddot- --~-+-t---r~~ ~--+t-t- - ---t-c-++~-ulf--

0 50 75 100

Figure 15 - Curves of Generator Voltage Drop and Copper Loss

41

1200

1000

800

600

800

0

0

~-

middot--~ 1shy --1 + bull l

100

I -

150 200

IIDOOED VOLTAGB (VOLTS)

Figure 16 - Curves of Generator Stray Power Loss

_ j

-bullshy -L---- shy middot -shy

250

- r

42

(5) The generator los os equal the sum of the eopp r

loss and stray power loss

~e efficiency or the turbine is taken as

etticiency u e =P out (8)Pin

~ample pound Determ1n1gg turbine Power Output

The following data are taken trom that ot Run 1-9-1

Line voltage 1040 volts Line current 870 amperesSpeed 355 revolutions per minute

The induced voltage 1a determined as follows

Line voltage 1040

Voltage drop 90 using Figure 15 with line current of 870 amperes and temperature ot 122 degrees)

Induced Toltage 1130 volta

The power output of the turbine is determined as follows

Generator output 90$0 (line voltage z line current)

Oopper loss 7 (using Figure 15 with line current of 870 amperes and temperatUe or 122 degrees)

Stray power lose 470 (using Figure 16 with speed ot 355 revolutions per miDUte and induced voltage or 1130 volts)

Turbine power output 9527 vatta

or turbine power output 1s 12z2 horsepower

43

The conversion of the calculated data to a constant

head is based on the conventional assumption of constant

efficiency regardless of turbine head For a constant head

ot 81 teet a purely arbitrary figure the tollowing relashy

tionships are ass1lJiled to be true

I ____L (9) (i)l72

(10)

For these two values the specific a peed may be combull

putedt

N t Jt VPt (11)8 243

Chapter VI

~RESULTS

A -Pr_e_ae_n_t_a_t_t_o~n g Reaultbull

Graphical presentation ot the results ot this te1t

are given as follows

Figure 17 -Turbine characteristics with 100~ dratt

tuba 1low area

Figure 18 - Turbine characteristics with 7S dratt

tube tlow area

Figure 19 bull Comparison ot power and etticiency at

over gate conditions between 100 and

75~ draft tube flow area

Figure 20 bull COZQparison of power and ettic1ency at

halt gate conditions between 100~ and

7S~ draft tube flow area

Figure 21 bull Comparison of power and etticiency at

over gate condition between 100~ and

So dratt tube tlow area

Figure 22 - Comparison in variation ot apec1t1c

speed between 100 and 75~ dratt tube

tlow area

50

45

20

-bull - 1--shy40

bull J-~ 30

~ ex

~ 20

~~ ~ -)q

I

~ - _

- -

10~ OF DRAFT TUBE FL(Jif AREA

CONSTANT HEAD OF 8l FEST10

POIER OUTPUT EFFICIENCY SPECIFIC SPEED

0 ~--------------_--------~------~------~ 400 600 800 1000 1200 1400

TURBINE SPEED (RPM)

Figure 17 - Turbine Char~cteristics with 100 Draft Tube Flow Area

50

46

-bulllle

~ 7 ~ OF DRAFt TUBE FLOW AREA

0 -~~-rl C05STAMT BEAD OF 81 mET 1J~

POIER OOTPUT ---+- ---o ~_H EFFICIDCY ~ I shy

bull ql SPECIFIC SPEKD - ~ -

bull ~ J 10 L rmiddotr- r- -

bullz- I

~~ 30 ~~--~----~~-

20 ~ ~ middot-shy

26

~~ 25

~0 ~r-----i (

Tbull -bullshy

400 600 800 1000 1200 1400

TURBINE SPEED (R PK )

Figure 18 -Turbine Characteristics with 75 Draft Tube Flow Area

47

EFFICIENCY 60

1-----shy

-~ 50~--~--~~-~middot middot middot middot r~-~----~~~~---4~-r~-~~gtt

II

POWER~ J ~ bull bull

u I

sH

40~------+-------+---- -~~--~~-~~~~

~----~rl 1 bull

I

I

0~--------------~------_------~--------

~ -OVER GATE CONDITION

COIJSTANT HEAD OF 81 FEET

0 o 10~ DRAFt TUBE

_-- _ 7~ DRAFT TUBamp FLON AREA II

10_~-----+--------r-------r----~~

400 600 800 1000 1200 1400

TURBINE SPEED (RPM)

Figure 19 middot - Comparison between 75 and 100 Draft Tube Flow Areas of Power and Efficiency at Over Gate Conshydition

48

t

bull --4 r ~- ~ middot~

70 1-----------+-~~~~~+middot ~ ~~ middot middot -~~--~~--------~~----~-+1

-~-

Atbull bull

lla-

60

amp0

40

20

10

oampOO

t _ - - ~-+- - -~-

l2 GATB COJIDITIOJJ

COJISTABT HJW) OF 81 JBET

o 0 lOQ( DRAFl TUB8 FLOI AREA

e-- - e 75 DRAFT TUBE FLOW AREA

800 1000

- r-

~

TURBIbull SPBIID (RPII)

Figure 20 - Comparison between 75 and 100 Draft Tube Flow Areas of Power and Efficiency at Half Gate Conshydition

49

60

50

-40

bull 30

IIQbull

20

10

0

400

- t - ~

EFFICIENCY

_J bull - bull bull

~ r r middot t -+ shy L -t -

OVER GAD COliDITIOI

CONSTABT BEAD OF 8l FBB

o o 10~ DRAFt TUBE FLOI ADA middot--- 5~ DRAF TUBE FLQPi AREA

600 800 1000 1200

Figure 21 -Comparison between 50~ and 100~ Draft Tube Flow Areas of Power and Efficiency at Ove~ Gate Conshydition

50

25

20

15

10

0

Figure 22

~- T -4 -t- -l --~-

t-~ I

middot --~- t ~---- _ __ _ + --

----~- --r-- --

~-=J-~-=-~ -==~ _ ~- -- ---f---1 - shy

CONSTANT HEAD OF 81 FEBT

o--o 1~ DRAFT TUBE FLltll AREA

75C DRMT TUBK FLCIJ AREAmiddot--middot-middot 600 800 1000

TURBINE SPEED (RPK)

Comparison of Specific Speeds for 75 and 100 Draft Tube Flow Areas

51

B Discussion 2 Result

Consideration of Figures 17 and 18 indicates the

overall eftioi ncy pattern or hill is significantly or

rounded for the 7$~ flow area than for the 100~ flow area

bia implies a greateP efficiency is possible at speeds

leas than or greater than design speed with an insert in

the draft tube However the muilDum efficiency is lemiddotas

Direct comparison at over gate conditions is made in

Figure 19 ~e same general trend is noted tor both the

etticiency and power curves for the 7$~ flow area case

The eurves show higher values at overspeed than do the

correaponding cWvea for the 100 flow area case It ia

not clear whether the curves have been shifted by the dratt

tube constriction or whether the curves simply bulge past

the normal curves at both overspeed and underspeed condishy

tions The power curves apparently peak near the aeme

point bullalthough maximum power is still obtained with the

normal draft tube area

For the comparison at halt gate operation shown in

Figure 20 a general improvement has apparently been made

by restriction of the draft tube flow area At every speed

the etticienoy and the power is greater for the restricted

tlow case The two ett1o1ency curves and two power curvea

are practically parallel throughout the speed range ot

teat

As the flou aroa i e decreased still farther a s1gn1

ticant change appears Reterr1ng to Figllle 211 tor the $0

flow area curves it a obvious that exit losses have

become excessive at the overgate condition because the

efficiency and power are everywhere leas than tor the case

of normal draf t tube area

Earlier it was pointed out t hat 1t the r esult s 1nd1bull

eated an increase in both power and ef tieiency- t hen it

could be assumed tha t the additional los s i ntroduced with

the draft tube insert is less than the diminished losses

due to leas shock losa and water passage losses For the

places where both the efficiency and power have been

increased we can assume that the insert has improved turshy

bine performance

For the places where the power haa been decreased

nothing can be said as to the elimination of ampbock loss

because the new lose present with the drat tube insert has

overshadowed any gains in eftecti Ve head upatJ-eam of the

insert

Near the peak of the efficiency hill howeve~ it may

be pointed out t hat shock loaa ie a minimum with a normal

draft tube and the insert merely adds an additional loss

with the resultant decrease in maximum efficiency tor the

7$~ flow area case

Perhaps the most s1gn1ticant set of eurves is shown aa

53

Figure 22 In this graph values of specific speed tor the

75 and 100~ flow area cases for both over gate and one

halt gate openings are plotted against turbine speed At

every speed and both gate openings the value ot specific

speed for th 75~ flow area case is greater than that for

the 100 t1ow area ease

Since the head is a constant for both situations this

may be interpreted in either of two ways trom equation

(11)

(1) For the same turbine apeed restriction of the

draft tube t1ow area resulted in greater turbine power

(2) For the same power amputput the turbine with 75~

draft tube flow area operated at a greater speed than did

the one with 100 flow area

Since the required diameter of a turbine varies

inversely with the speed the second interpretation could

be stated such that a smaller turbine could be used to

develop the same power output

Whether viewed trom the aspect of increased power

greater speed or reduced size the performance of the turshy

bine with reduced draft tube flow area is superior to that

with the nolmal flow are in the draft tube

The curve of specmiddotific speed versus turbine speed for

the so draft tube flow area case at over gate cond1t1ona

was not included in Figure 22 This curve lies below that

for the 100~ flow area c se at all speeds

In elaboration ot the second interpretation of Figure

22 attention is directed to the relative magnitudes ot

increased apee1f1c speed tor the two gate openings Assumbull

ing that the increase in specific speed implies a shift ot

the power curve to the right along the turbine speed scale

the power curve would be shifted more tor tbe halt gate

opening than tor the over gate opening

It thia trend could be extrapolated to the other gate

openings the tendency can be seen tor the line ot beat

speed to rotate toward the line of the operating speed as

illustrated in FigtU-e ) The advantage of this has already

been discussed

This particular turbine has a low specific speed tor a

reaction turbine Aa the rated value of apecitic apeed tor

reaction turbines increases the line ot beat speed departs

even more radically from the line of operating bullpeed It a

test similar to this were conducted on a reaction turbine

ot gleater specific speed it is pJobable t hat the rotation

ot the line of beat apeed would become more p~onounced

The scheme used in th1a teat had two obvious dr wbull

backs The first was the decision to leave all the wicket

gamiddottes installed tor all conditions ot the draft tube

These gates predominated in control of the tlow The

inserts added to the draft tube merely acted as auxiliary

55

contrGla

The aecond drawback was the choice or device to place

in the draft tube The reasons foll selection of this type

of device have been previously mentioned It is to be

anticipated that adaptation ot dratt tube flow control

would result 1n a better device for an actual turbine

installation Such apparatus might take the form of a

pneumatic bladder or a h7drau11oally operated variable

venturi section in the draft tube It is conceivable that

the gate as used in this test might be adapted also

Chapter VII

OONCLtJSIOfS

From the results of this test the following eonolubull

e1ona aa to the effect ot a variable draft tube flow area

on the performance or a r action turbine may be drawn

(1) The effect ot a variable draft tube tlow area 1a

generally favorable upon the operat1Gn ot a reaction turbull

bine because or the tendency tor the line or beat speed to

rotate toward the line ot operation This resulte in

better performance of the turbine at partbullloads

(2) he etf1o1ency eh111 tor the turbine beeomaa JDore

tlat at the top leading to a smaller max1JilWD effic1enc7

but e reater etticieney at other pointe of operation with

the insertion ot an auxiliary control ror the rate ot tlov

in the draft tube

(3) The power output of the turbine will increase at

over speed over gate conditione as well a at part gate

conditions with the proper amount or draft tube eonatr1cbull

tion or flow

(4) It is possible to eliminate at least partially

eddy type shock loss by tho introduction ot flow control

in the draft tube

BIBLIOGRAPBl

1 Addison Herbert A treatise on applied h-draul1cs New York Wiley 1954 724 Pbull

2 Allen o M and I A Winter middot Co111parative testa on experimental draft tubes Tranaact1ons ot the American ociety ot Civil Engineers 87t893bull970 1924

3 Barrows a E Water power engineering 3d ed ew York McGraw-Bill 1943 791 Pbull

Bovet G A Modern trenda in hydraulic turbine design4middot in Europe Tranaactions of the American Society ot Mechanical Engineera 75975bull993 1953bull

s Oreager William P and Joel D Justin Hydroelectrichandbook 2d ed New York Wiley 19$0 1151 Pbull

6 Daily Jamea w Hydraulic machinery Int Hunter Rouses Engineering hydraulics Hew York Wiley 19$0 p 8$8bull99

Daughertybull Robert L Bydraulie turbines ew Yorkbull7middot MoGrav-Hlll 1920 281 Pbull

8 Daugherty Robert L Inveat1gat1on of tne performance ot a reaction turbine ~anaactiona or the American Society ot Civil Engineers 7811270bull1304 1915

9 Davie L M Model and prototype testa Int Trend in hydraulle turbine practice symposium lranaactions ot the American Society ot Civil Engineers 1o63S3middot368 1941

lfJ Doland James J Hydro power engineering Hew Yorkbull Ronald 1954 209 Pbull

11 Gandy Theodore s and Elmer c Schacht Direct curshyrent motor and generator troubles operation and repair New York McGraw-Bill 1911 293 Pbull

12 Gibaon Arnold H Hydraulics and ita applications5th ed London Constable 1952 813 Pbull

58

13 Button s P Component loases in Kaplan turbinebull and The prediction of efficiency from model tests Probull coedings of the Institution or Mechanical Engineers168743-762 1954

14 Knapp R T~ Oavit t1on mechanics and its relation to the d sign or hydraulic equip ent Proceedings or tne Institution ot Mechanical Engineers 166150bull16) 1952

15 Langsdorf Alexander s Principles of direct curHnt mach1nee 5th ed New York r~cGrawbullH1ll 1940 746 Pbull

16 Lsrner Chester w Characteristica of modern hydraubull lie turbines Trans e~ions of the ~~erican Society ot Civil Engineers 66306-386 1910

17 Linsley Ray K Jr and Jobulleph B Franzin1 Eleshyments of hydraulic enginebullring New York McGrawshyBill 19$5 $82 Pbull

18 Mead Daniel w Hydraulic machinery llev York McGraw-Hill 1933 396 Pbull

19 ead Daniel w Water power engineering New York McGrawbullRill 191S 843 Pbull

20 Mockmore Charles A Part gate operation at water turbines Corvallis Oregon State College Department ot Civil Engineering 1933 11 numb leaves (Unpubshylshed typescript)

21 Mockmore Oharles A Flow characteristics in elbow dratt tubes Transactions of the Amez-ican Society ot Civil Engineers 103402middot464bull 1938

22 Moody L F Hydraulic machinery In c v Davis Handbook ot applied hydraulics New York McGrawshyHlll 1942 1082 Pbull

2) Ptau At-nold Hydrbullulie turbine handbook ld ed Milwaukee AllisbullOhalmers ManufactUIing Company 1948 70 Pbull

RheingalUI w J Recent developments in Francis turshybines Mechanical Engineering 74189-196 1952

25 Russell George E Hydraulica 5th ed New York Henry Holt 1942 466 Pbull

26 Safford A and E P- Hamilton American mixed tlow turbine and ita setting Tranampactions or the Amerieal Society of Civil Engineers 851237bull1)56 1922

27 bull Spannhake W1lhe1Dh Problems or modern pump and tur b1ne design Transactions of the American Society of Mechanical Engineers 56e22$-248 1934bull

28 Sutherlandraquo R A Better ethod or representing and middot tudying water turbine performance ~ansaetions ot thmiddote American Society of Mechanical Engineers 68t675bull 686 1946

29 Teats ot five models or draft tubes tor turbines Engineering News-Record Pbull 182-184 Aug 2 1923

30 White w M American hydztaulic turbines Mechanical Engineering S2t390bull39S 1930bull

31 White w M lhe hydraucGne rega1ner1 its developmentand appl1eat1ons 1n hydroelectric plants Meohanlobulll Engineering 43t37Sbull380 1921 middot

32 Winter I A Economic principlebull in designbull Int Trend in hydraulic urbin practice bull a ampoeiumTranaaot1ona ot the American Society ot Civil Engineerslo6332bull3S2 1941

33 Wiel1cenua G F Fluid mechan1ca or turbo-machineryNev York McGraw-Hill 1947 613 Pbull

APPENDICES

c

Appendix A

NOATIOB

A Angle between the absolute velocity vector and the tangent to the rwmer Subscripts 1 and 2 refel to entrance and exit ot the runner blade

B Angle between the relative 1elooity vector and the tangent to the rwmer Subscripta 1 and 2 refer to entrance and ezit or the runner blade

Angle between the tangent to the runner blade tip and the tangent to the runnel- Subscripts 1 and 2 reter to entrance and exit of the rt1rmer bladebull

Blade angle-gate opening conetant defined by equation (1)

e 09erall efficiency

g Gravitational acceleration assumed constant at 322 teet per second per second bull

H Turbine head detined by equation ($)

m Exit loss coeft1e1ent

Turbine speed expressed in revolutions per minute

Turbine speed under a constant head of 81 teet

specitic apeed of the turbine under a constant head ot 81 teet

p Power output in horsepower ot the tvbine

Power output of the turbine Ulder a constant head ot Sl teet

Pl- Pressure head at entrance to the tUlb1new

l1 Peripheral velocity ot the runneP Subacr1pta 1 and 2 refer to entrance and exit ot the JUnllampr blade

62

v Relative velocity reaulting trom the combination ot the absolute water velocity V and the runner periphshyeral velocity u Subscripts 1 and 2 refer to entrance and exit ot the runner blade

v] Relative velocity vector necessary to produce a tanbull gential entry into the runner blades

V Absolute water velocity Subscripts l and 2 refer to entrano and exit ot the runner blade

v2 Velocity head Subscripts 1 and 4 reter to the ~8 entrance to the turbine and the tail~ace wate~

w Unit weight ot water assumed constant at 624 pounda per cubic toot

V Weight rate ot flow in pounds per aeooncl

XX Velocity component ot ahook See Figule 2

Z Elevation head Subscripts 1 and 4 reter to entrance to the turbine and the taibace water surfacebull

Appendix B ORIGINAL DATA-Run

lfwnber

0-4-1 0-4-2 0-4-3 o-4-4 o-4-S o-4-6 0-4-7 0-4-8 0-4-9o-4-lo o-4-11 o-4-12 0-4-13

o-6-1 o-6-2 06-3 o-6-4o-6middotS o-6-6 o-6-7 o-6-8 0-6-9 o--6-lo o-6-11

Speed

rmiddot2middotbullmiddot(1)

336 38$ 451 S$9 620 669 6lt)$ 120 787 860 932

102imiddot109 bull

352 355 443middot 543middot 620 654AJs32

911 1001 1111

~essure Head rt (2)

410 410 416 426 431 43-7 439 44-9 452 467 482 soo $1 bull $

350 351 35middot7 )66 37-9 37-9 392 41 bull 3 43middot3 460 489

Elevation Bead

fjj $7 $7 $7 $7 $7 $7 51 57 5-15858 $8 58 56 56 $6565656 51 575As5a

Velocit Head

flj 07 07 07 06 06 06 06 os 05 os0404 03

09 09 oa o8 o8 os 07 07 06 o~o

Total Head rt ($)

47middot4 4A44 o 489 49-4 soo $02 $11 $14 $29 5imiddot45 2 576

41 bull $ 416 421 430 44middot3 44middot3 456 47-7 496 523551

Plow

lbtjec

326 324middot317 311 306 30029middot28 middotmiddot middot 386 275middot260 240 218

359 36~35 bull 349 345middot 339 330 318 300 273 240

Line Potential

vyqjbull 1060 1220 ~-0o 1920 2150 2000 2$60 2000 1940 18)015io11 o

1000 1100 139bull5 1760 1925 16$0 1620 1610 1540 1330 870

Line Current

amlscs 960 900 830 740 730655 70bull 0 530 660 600 5imiddot54 6 )60

982 930 860 780 ~3-545

79-5 74-5 670 560 370

P

Appendix B ORIGINAL DATA (Continued)

Run Number

Speed

Pbulltmiddotbullmiddot )

leasure Head ft(2

Elevation Head tt(J)

Velocity He-dfmiddotj

Total Bead tt($

Flow

lbstsec( )

Line Potential vo~ta( )

Line Current

amjs (sect

0bulllt)-1 0-9-2

3ll6 398

28o ~~1

$6 56

1o 10

346 347

390 365

1ooo 1190

aao 835

0-9-3 0-9-4 o-9-S

472 565 632

292 305 312

$6 s6 56

10 o9 o9

)$8 J7~o 37~7

381376 37o

1)6614oo 141o

820 ass ass o-9-6 0-9-7 0-9-8 o-9-9 0middot9-10

680 120 762 844 920

)24337346 366 390

56 $6 56 57 $7

09 os o8 oa 07

)89401 410 431454

367~ 357348 34o 322

1400 1J6o l36o 1310 1170

843 820 7957So 67~0

0-9-ll 0-912

1001 1100

41 bull 7 45-3

s 7 6~0

06 os 480 $18

299 268

980 65$

560 36~5

1-4-1 1-4-21-4-l1-4shy1-4-5 1-4-6 l-4-7 1 4-8 1-4-9 1-4-10 1middot4-ll 1-4bull12

354middot452 562 62q 674shy102 752 760- 863 932

1022 1100-

)82389 4014oa 416 41--7 423 428 44-2 45-7 486 49-2

51S757 51 5-7 5middot15zs sa $8 58 59

07 07 06 06 06 06 06 os o bull o 04 o J

446 45-)46middot4 471 ti7-9480 q86 491505 $19 548 55-4

)28 320 311 306 300 295 291 286 269 2582iimiddot21 bull

1080 14Lo 1550 153-5 1470 141-0 1385 1310 1310 1230 1120 855

970855 875 91-0 94~0 975 966 995 860 77-S 610 4fo

0 ~

Appendix B ORIGINAL DATA (Contirmed)-Run Speed Pressure Elevation Velocity Total Flow Line Line

Number Head Head Head had Potential Current rtjjmbull t~ bttec vyfs am~a12) ( ) ti fli 8

1-6-l $6 33$ $6 0bull9 400 364 1100 93 0 1-6-2 41 34laquo2 $6 oa 406 JS7middot iios a5s l-6-3 500 3~0 5bull6 os 356 1 1 o aos 41middot~1-6~4 35bull4 5-6 oa 41middot 352 16~0 82 0 5~1-6-5 5 bull 36_2 Sbull6 08 42bull6 349middot 161 ~ 0 86~0 1-6-6 622 366 $6 oe 43bull0 345middot 158 0 88~$ 16-A 649bull 37bull1 56 os 43-S 342middot 1570 895 1~- 386 57 07 46-0 192 ) 125A44 333middot 1-6-9 3) 404 5middot1 07 468 317 1620 675 1610 911 42-4 5-7 o6 48-7 298 168 0 61 0 1-6-11 999 451 56 os Sl ll 276 ~2-0 530 1-612 1115 485 58 04 54middot7 238 90 )3 0

1middot9-l 355 279 56 10 )45 385 1040 870 1-9-2 399 28J $6 10 )49 38$ 1140 86 5 l-9-3 ~ ao 291 56 ~0 35middot1 J8J_ JJ6o 815 1bull9-4 579 303 56 09 )68 375middot J4JO 830 l-9bullS 40- 313 )6 09 31middot8 370- 1460 82~0 1-9bull6 679 2) 56 09 3 bull8 364middot 1670 710 l-9-7 682 319 56 o9 384 ) 62 1460 79 5 l-9-8 724 33middot5 56 o8 399 3$6 bull 1480 76 -5 1-9-9 762 34middot3 $6 0 bull 8 407 )48 14910 13middotS 1-9-10 833middot )60 5middot7 os 42$ 339 144$ 686 1-9-ll 926 39middot1 5-7 07 455 318 1290 600 1-9-12 1000 41middot3 0-6 476 298 1115 510$ ~ 1middot9-13 1105 452 s o4 $14 2$6 710 )10

~

Appendix Bt ORIGDIAL J (Continued)

Run Speed Pressure Elevation Velocity Total Plow Line Line Number Head ltead Head jlamp$d P()ten~ibulll Current

r~~~m ft ft lbs~seo voltattj rgj twimiddot t 1 t2gt lt3 ou t ( rt

2-9-1 384 289 S 6 10 35 5 1400 1170 810 2-9-2 443middot 29$ $6 ltimiddot9 360 379middot 11(0 87$ 2-9-J 536 30bull 3 sc 09 )68 374middot 1)40 84 bull) 2-9-4 571 306 $6 09 3~1 372 120bull 0 955 2-9-5 623 316 S6 09 J l )6S UJSo 77$ 2bull9-6 669 327 S6 09 )92 )61 1240 905 2-9bull7 712 )39 56 os 40-3 351 12(0 86 bull0 2-9-8 ~5$~ J48 56 oa 412 348 1290 81 bull ) 2-9-9 04 )63 56 oa 42-7 339 12ltJO 76$ 2middotmiddot9-10 8$2 376 5middot1 07 440 33~- ~ o 710 2-9-11 955 394 5-1 o6 457 300 1100 506 2middot9-12 1000 421 $7 06 48middoti 295 1020 $18 2-9bull13 110~ 463 56 05 $2 267 620 3~0

oshy0

Appendix Gt CALCULATED DAgA

Turbine Run Generator Generator Turbine Turbine Efficiency Turbine Turbine Specit1c

Number OutputKWlt21

Loa~Jes KWlol

Outut K bull (H)

Input RP 12)

middot Percentlt13gt

Speed r~Jmiddot(

0ltput HP ~1

Speed r-m

( 6) middot

o-4-1 0middot4-2 0-4-3 0-4-4 0-4-5 0-4-6 O-qmiddot7o-4-8o-4-9 0-4bull10 0-4-11 o-4-12

1018 1o9a 1220 1)62J40214oa1J4oo 1357 1320 1164 997 718

046 o59 071 092 096 1071oo 134 104 100 109 107

14261sso 17)01948 2008 20322011 1999 19 09 1708 14-84 11o6

281279 27-7 276 215 273271 268 268 26h 258 24-5

soa 555 62$ 705 7)1145 742 74-6714645 51s 45-1

440 sos 585 720 195 sso sao 9$$ 985

1065 1135middot 1230

318 357 319 416 422 419412 39middot9 378 324 260 191

102 12bull4 148 191 21bull 3 22o 233 249 24924middot9 238 221

0-4middot13 418 104 699 228 306 1300 117 18)

o-6-1 982 045 1376 271 $08 496 376 124 o-6-2 o-6-3 G-6-4o-6-5 0-6-6

1023 1200 13 73 J415 139h

051 0middot66 oaa ()bull 96 088

14-39 1696 1958 2026 1986

276 27middot4 273 278 274

$20 61 8 717 7)0726

q95615745 8)5685

390 ll5middot3 sos soo 490

127 170 218 243 2$$

o-6-7 o-6-8 o-6-9o-6-lo

1288 1199 1032 7-45

o9o 094 09$ 096

1846 1733 1511 1128

274 276 271 260

67S 629559 43middot4

980 1085 1165 1245shy

436 )83316 21bull 7

266 276 270 239

0-6-11 322 1oo 566 2141 2JS 1350 101 177 0 --4

Appendix C CALCULATED DAlA ( Continued)-Run

Number Generator Generator

Out2ut Losaes xw LW- 12gt (lO)

Turbine Out2ut

ltPlJ

Turbine Inat lfP Jig)

Etpound1e1ency

PireentDl

Turbine Sed x-~m( 1

Turbine OutEut RPJl)

Turbine Specific

SeeedrIbullntbull

( 6)

o-9middot1 0-9-2 0-9-3 o-lt)-4 09-$ 0bull9-6 0-9-7 0-9-8 0-9-9 0-9-10 o-9-11 0-9-12

aao 994

111$ 1197 1206 1180 11)21081 982 784 5-49 2)9

0middot45oss o6$ 070 07$ 0-77 (l77 or~ o s06o 8 096

123~ 1402 1$80 1698 17bulllS 168$ 16bull18 ~middot5430 1151 a~J4 9

24middotgt24middot3248 25~25 260 260 259 267 266 26middot1 2S2

sos 577 63-7 671 676 650 621 60036J4

327 178

$) 610AlO 3$

92S 980

102$ 1070 1157middot 1230 1300 137Smiddot

44middot4 soo 523 ssomiddot 540so6 46-5 432 368 274 18~8

J46 176 21-1 255 2802s_A 28 289 288 265 231 168

1-4-1 1-4middot2 1-4-3 1-4-4 1-4-5 1-4-6 1-4-7 1-J-8 1-4~9 1-4-10 1-4-11 1-4-12

10bull48 1231 13-S6 1397 1)821375 1))8 1303 1127 953 683) 51

048 067 o7A07 0 bull79 oa1 oss o bullao osa 0lt)0 096 099

J468 1740 1921 1978 1958 19$1 1911 lSSi162 1)98 1045

603

266 264 262 262 261 2512$7 2$6 24middot7 24-3 233 217

551 660 13middot3155 75-6 7~-97 middot4 72$ 67 51middotJ 44middot9 21middot1

475 605 A4220

875middot 910 970_

1000 1090bull 1166 1243 1330

5816

44middot444middot5 430 427 412 392 329 273 188 l0-7

117 101 204 22$ 2)7245 2562sa 257251 222 179

a-C))

Appendix Ct CALCULATED -DATA ( Ocntinued)

1-6middot1 1023 o$2 14-41 26S 505 41~6 26~

54middot5 13middot3l-6-2 1201 067 1boo 625 47-9 17shy~middot41-6bull3 1296 oA9 1 middot43 26 9 700 so5 20bull 4 l-6-4 l3j5 o 0 19~09 268 71bull3 A5o 514 222 1-6-5 1) 5 o81 19(gt4 271 725 51-5 238 l-66 1398 081 198) 27-0 736 8 S13 252~-middot l-6j 1405 083 199i 211 733 885 $middot06 2$9 l-6 13middot9~ 103 2amp 0 279 71 8 985~ 467 ~-69 1228 1 bull 02 17-SS 270 661 109$ 407 ~3~ l-6bull10 1025 100 lSll 26i 573 1175middot 27~S32middot~l-ampu 153 1-00 llft3 26 444 1270 22 24bull8 1bull6-12 294 100 52a 231 22 3 1360 95 172

1-9bull1 904 048 1275 2J4Z $28 S4$ 459 1$2 1-92 98$ oss 13-92 24middot4 57-0 6JO 49bull1 176 1-9middot3 1110 066 1$76 24middot9 63middot4 I2o 536 21-7 l--9-4 1187 072 1685 251 66$ 5 $$ bull 0 261 1middot9-5 llltJ7 1710 25middot4 67-3 93$ 536 28~20-671middot9-6 1186 o 8 1708 25-7 67) 980 $15 2691-9- 1161 oBo 1660 2$middot3 6$6 990 508 29-1 l~- ll-32 oB) 16sect0 2$8 632 1030 471 291 1-9bull9 109$ oa5 2$7 614 1075 29S~middot 0 4imiddot41-9-10 9~91 oas 262 S$1 1150~ 3 o 292 1-9-11 o9o u57 12JiO 21gt 26-77middot74

-45 26sect ~middot91-912 $69 091 sas 25 middot3 1)0$ 196 2J-8 1-9-1) 220 098 426 2)9 178 1390middot 84 16 6

0 0

Appendx C CALCULATED DATA (Continued)

Turbine Run Generator Generator lurbine Turbine Eft1e1eney Turbine lurbine Spee1f1c

Number Output Losses Outit Input Speed Output SPed middot k_-V KW R _ H_bull_P Percent r Thm HP rpm_ (9) tlo) 11) middot (12 _) (lJI ( ) (1$ (14)

2-9-1 9--46 055 1)62 258 528 580 164 2-9-2 1024 056 248 58 4 665 4 9 191iimiddot48 4~middot0 2-9-3 1132 067 05 2$0 641 795 52q 237 2-9-4 1148 065 1027 2$1 -~8 845 525 252 2-9-5 11 77 oso 16-83 253 6 910~ 522 270 2-9 6 1122 071 1600 251 622 960 47-5 2722-9-A 1092 015 1562 257 608 1010 445 2z12bull9- 1052 079 1514 261 580 1060 41middot7 2 2 2middot9-9 986 o82 ]429 26) 542 1105 372 277 2-9-10 915 086 1340 268 500 1160 334 27-6 2-9-11 638 087 972 254 )81 1270~ 229 250 2-9-12 )28 090 828 259 )19 1295 179 226 2-9-13 192 094 383 2$ 6 150 1370 7 3 152

-3 0

Page 27: The Effect of A Variable Draft Tube Flow Area on the

20

CURVEAbull

TURBINE SPSBD TURBID SPEKD

POIBR OOTPOl

Figure 3 - Turbine Performance Curves

21

22

(2 peat (l) with the gate installed in the drat

tube

(3) middot Converting middot all data to a constant head compare the

powere and effioiencies at the same wicket gate setting and

turbin speed tor the two cbullses

If the ddition or the gate indicates an improvement

in power output and efficiency and the powe~ curve shifts

to the right along the turbine apeed scale the advantage

ot draft tube con~ol of the flow will hav been demonshy

strated

Chapter IV

A E9J11pment

ih turbine used in this test is lJ 5 1nch Pelton

reaction turbine with a rated output ot 30 horsepower under

a head of 56 feet at a speed ot 720 reYolutiona per minute

Views of this turbine are hovn in Figures S and 6 The

turbine is installed on a concrete pad located over an open

channel in the Hydraulics Laboratory at Oregon State Colshy

lege The date of manufacture of this turbine was 1915

The water was delivered to the turbine from a sump

reservoir by two pumps operating 1n parallel Each pump 1a

an 8 inch Pelton double suction centrifugal pump witb a

rating of l$00 gallons per minute at a head ot 75 teet with

a speed ot 1175 revolutions per minute Tbe inlet tlange

ot tne turbine is $pprox1mately 18 feet above the center

line of the pump

A direct current generator was coupled to the turbine

to receive tne power d veloped as shown in Figures 4 and 7 The generator is a Spr gue Electrodynamometer rated at SS horsepower with a speed range of 7$0 to l$00 revolut1one

per minute The classification is type LO 26A 2)0 volta

Figure 5 - View of Test Turbine

Figure 6 ~ View of Test Turbine

and 149 amperes lbe generator ti ld was aepar tely

excited using direct current from a motor g n r tor ampt

(l$ p 4~8)

The power output of the generator waa dissipated in

the water rheostat (3 p 488-489) shown in Figures 9 and

10 The galvanized tank contain d water ot variable d pth

on an electrode ot cast iron m aauring 1bull x 1 x 1

In the initial installation of the turbine it was

intended that the power output should be measured with a

Prony brak bull For th purpoa68 or this teat it was decided

that the brake was too instable and the generator was

substituted The platform for raising the generator the

nee asary two teet for alignment was built out of available

material In this case heavy laminated wood blocks reiashy

torced with other timbers were used and bolted through the

concrete deck (11 Pbull 36-$7)

Due to the light concrete deck the lack ot mas in

the platform and the slight misalignment in the flexible

coupling ao e vibration waa encountered It seemed to

ncr aae linearly to a maximum at the speed of bout 750

revolutions per minute Above this speed no vibPation was

noticeable The vibration waa not se~ere and does not

appear to have materially affected the test results

26

B Intrumentat1on ~ eaeur1ng Devices

The pressure head at inlet to the turbine vaa meaave4

bymeane ot two )6 inch waterbullmeroury manometerbull connected

in series as shown in Figure 8

The terminal voltage ot the generator vas meaeured by

a laboratory voltDleter with a range to )00 yolta and callbull

brated to within 15 Yolta

The armature current bull and hence the line current was

measured by a laboratory ammeter with a range to 150 amperea

and callbrated to w1 thin o 7S amperes

Tae rate ot tlow was established by weight and time

meaeurementa The weighing ank has a capacity ot 121 000

poundsJ the weight belng indicated by Toledo direct reading

scales Timing was done with a hand atop watch with clivibull

aion ot 02 second

he ~ater level in the tailrace was dete~1ned by a

hook gauge lhie was read to the nearest 001 toot

The turbine and generator speeds were eaaured by a

hand tachometer The technique of almost cont1nuoua readbull

ings of the speed gave an error ot no more than 5 revolubull

tiona per minute

c Operational Procedure

Atter the water level in the aump was checked to

insure an adequate auppl7 the puapa were primed and

27

Figure 7 - Test Generator and Plattorm

Figure middot8- Instrument Board and Field Rheostat

28

started After venting they were valved for operation 1n

parallel

The motor generator set was started to supply the

field current and the circuit breaker was closed Water

wa added to the water rheostat to the level shown in

Figure 10 ~ field current wae minimized by cutting in

all the f ield resistance in the field rheostat of Figure 8

The l2 inch gate valve shown in Figures 5 and 6 waa

slowly opened and the turbine and generator brought up to

speed The 12 inch gat valve and turbine were vented and

the pumps were checked to insure neither had lost ita prime

lhe water rheostat offers very steady load 1f the

water level is essentially constant and the water temperabull

ture 1a fixed () p 488~89) In order to maintain this

constant temperature it was decided not to circulate the

water in the rheostat but rather to allow the water to

boil thua achieving the desired result A standing wave

was set up on the face ot the electrode by the boiling

action but a atable load was eatablished except at very

low water leYels where th11 agitation led to fluctuationa

in the line current

After putting the turbine and generator on the line

maximum power was dissipated in the rheostat by redueing

the turbine speed to between oSO and Soo revolutions per

minute Salt vas added to the rheoetat wat r to increasemiddot

29

Figure 9 - View of Water Rheostat

Figure 10 - View of Water Rheostat

Separate Field ExcitationFrom Motor-Generator set Compound Water-Mercury

---shy

re Manometer

I Q)

~ 0

~

Book Gauge

Open Channel

I

Slap Reservoir

Figure 11 - Wat~r Flow Diagram and Electrical Layout

31

waiting pe~iod ot perhaps an h~ followed

while the boiling point or the water wbulls reacbe4 During

this ti+ne the manometer was vented end eheoked electrical

measur1ng 1nstlUments were connected end the hook gauge was

adjusted tor elevation

It required about two- houtte tor the generator to reach

its normal operating tempe-ratu~e_ After the water in the

rheostat and generator had reached their operating temperabull

turea it was possible to begin the taking of data

The only vaPiable which was controlled wee the turbineshy

generator speed However the upper l1ut1t of safe line

current was slightly over 100 ampJilPampPes and the eireuit

breaker would open when the current reached lOS ~ere bull

Control was exercised by means ot regulating the water

level and salt 1n the water rheo tat and the res1stsnoe of

the tield rheost t~

The etfeet ot each type ot regulation on the three

variables is shown below

Volta Aaperebull Speed

Inc Dec Inc Dee~ Inc Dec

Wa~e1 Level Inc Dec~ X

X X X X

X

Salt Concentration

Inc Dec X

X X X X

X

field Resistance

Inc Dec

X X

X X

X X

32

Jlot all methods gave the ame amount ot change in a

given variable and a period of experiment and trial led to

the following scheme starting the rune with the lowest

turbine speed the water level was high with a high amount

ot salt and the field resistance was cut completely out

Aa it became necessary to increase the speed tor each

aucceasive run either cutting in t he field resistance

decreasing the salt concentration or lowering the Vater

level would produce the desired result However decreasbull

1ng the salt concentration had to be done Without a net

gain in water which led to a tluahing procedure that was

not particularly good because cold water was introduced

which required time to heat to the boiling point Cutting

1n additional field resistance was a good method but th1a

increased the amperage possibly to the point of opening

the circuit breaker Lowering the water level was aatiashy

factol1 until the level got too low causing the current

fluctuation previously mentioned Actually it turned out

that a combination of lowering the water level and cutting

field resistance in would carry the speed from ita minimum

to 1ts maximum value it the proper choice were made each

time the speed waa to be changed At the conclusion of

each aet of runs at a high speed the water level would be

low and the field resistance high

33

TURBINE

PAD AND DECK

TAILRACE

WATER SURFACamp

CONCRETE

DRAFT TU1B INSERTS

7 5( DRAFr TUBE

FLltJI ARIA

5~ DRAFT TUBE

FLOI ARSA

Figure 12 - Sketch of Draft Tube and Test Inserts

34

Figure 13 - View of Draft Tube Insert

Figure 14 - View of Draft Tube Insert

D c __ ~s_middot hedu_le of

A number was assigned to each run The fi~st number

applies to the draft tube tlow areas

1 bull 100~ flow area or 0~ oonatriction

2 - 7S tlow area or 2$ conatr1ct1on

3 SoC flow area or so~ constriction

The second number refers to the wicket gate openings

9 over gate opening

6 bull intermediate gate opening

4 bull one h lt gate opening

The third number 14entif1ea the location of the particular

1Wl in a set ot rona made at a given dratt tube tlow area

and wicket gate opening

fnua run number 1bull4bull10 would identity this as the

tenth run ot a set made at halt gate with 75 ot the draft

tube t1ow area

Rune w re made tor a g1yen dratt tube condition

Firat tor tull 41-aft tube flow area seta ot rune were

made for the overgate halt gate and intermediate gate

conditione An insert was placed in t he draft tube and

rune based on the same gate conditions were made tor the

7S~ draft tube flow area case The insert was then changed

to allow only $~ draft tube flow area

The inserts are sketched 1n Figure 12 and photographed

ln Flgurea 13 and 14 They oonaisted of circula~ segments

36

or l2 ineh plywood mount 4 on wooden legs 10 inches high

The 1nse7te were placed in position and secured by th use

ot a-clamps on the legs and the outside ot the bottom of

the draft tube The obvious disadvantage to this method

waa the neoeasity tor draining the water from the tailrace

tor a change ot 1naert The advantage vas of course the

simplicity ot design and construction

Chapter V

DATA-A Original Data

The normal data-taking crew consisted or two men

Assuming adjustments having been made to secure a certain

turbine speed (aee section on Operational Procedure) one

man would take semi-continuous speed readings with the hand

tachometer until a state or rotational equilibrium was

reached This could be only a period or two minutes up to

ten or tifteen minutes As soon as steady speed was

assured the data taking would begin The second man went

to the weighing tank Where a minimum ot three weighingamp

were made The requirement was to get three consecutive

readings such that the ditterence between tbe smallest and

largest time did not exceed 04 seconds The time to

collect a given weight ot water was then assumed to be the

arithmetic average of the three times He then went to the

hook gauge determined the hook elevation and then

recorded the data on the data sheets The first man meanshy

while had taken readings of the line voltage line current

and manometers and checked the turbine speed by multiple

readings During the length of the run all values were

38

checked to determine mean values for recording

The minimum length of one run was about five minutes

If one or more measure ants tended to drift during the run

all values wer discarded and a new run began as soon aa

qu111br1um was stabl1shedo

B -0-al_e_u_l_a_t--d Data

The h d on the tu~bine 1 defined by

($)

The maxtmwm velocity V4 was equal to about o8 tampet per

secon4 which makes it a negligible quantity when converted

into velocity head

An engineerbulla level was used to deterine the d1ffePshy

ence 1n elevation between the compound water-mercury manoshy

meter and the hook gauge Using this value the equation

for turbine bead becomes

where z4 is the hook gauge reading

The rate of flow 1 cent

w weight or water collected average time to collect

The inlet velocity v1 vas calculated by dividing the

weight rate or flow by the specific weight of water and the

)9

area ot ~e inlet pipe This was equivalent to dividing

the weight rate of flow by 490 Then the power input to the turbine is equal to

WHpin rri

10 (6)

Also

(P ~ut) Turbine

(P out) + Generator

(P lost) Generator

The power output of the generator is simplJ the

produot ot the terminal voltage and the armature (line)

curPent The power lost in the generator can be subdivided

into copper losses and stray power losses lo evaluate

these cunes based on losses of an identical generator

11leampsured by the Department ot Mechanical Engineering were

used The loss curves are reppoduced in part in Figures

15 and 16

Determination ot generator losses proceeds as tollowau

(1) From Figure 15 detem1ne the vo1tage drop in the

armature circuit using the temperatures of 1220 F and the

meaaured current

(2) The induced voltage is t~e sum of the terminal

voltage and the voltage drop 1n the armature circuit

() Entering the induced voltage and the turbine speed

into Figure 16 the stray power loss can be determined

(4) The copper lose can be evaluated from Figure 1$

using the measured current and the temperatlll-e of 1220 P

40

25 ~------~--------~--------~------~

U) -U) - 20

f-4 ~

-~ -gt 0

0

VOLTAGE DROP

~ - i -

- bullbullbull bull - -middot-middot -+ ~- + -t--+ ~ - ~ middotbull ~-~ middott- -+----- _ -4 middotmiddot- --~-+-t---r~~ ~--+t-t- - ---t-c-++~-ulf--

0 50 75 100

Figure 15 - Curves of Generator Voltage Drop and Copper Loss

41

1200

1000

800

600

800

0

0

~-

middot--~ 1shy --1 + bull l

100

I -

150 200

IIDOOED VOLTAGB (VOLTS)

Figure 16 - Curves of Generator Stray Power Loss

_ j

-bullshy -L---- shy middot -shy

250

- r

42

(5) The generator los os equal the sum of the eopp r

loss and stray power loss

~e efficiency or the turbine is taken as

etticiency u e =P out (8)Pin

~ample pound Determ1n1gg turbine Power Output

The following data are taken trom that ot Run 1-9-1

Line voltage 1040 volts Line current 870 amperesSpeed 355 revolutions per minute

The induced voltage 1a determined as follows

Line voltage 1040

Voltage drop 90 using Figure 15 with line current of 870 amperes and temperature ot 122 degrees)

Induced Toltage 1130 volta

The power output of the turbine is determined as follows

Generator output 90$0 (line voltage z line current)

Oopper loss 7 (using Figure 15 with line current of 870 amperes and temperatUe or 122 degrees)

Stray power lose 470 (using Figure 16 with speed ot 355 revolutions per miDUte and induced voltage or 1130 volts)

Turbine power output 9527 vatta

or turbine power output 1s 12z2 horsepower

43

The conversion of the calculated data to a constant

head is based on the conventional assumption of constant

efficiency regardless of turbine head For a constant head

ot 81 teet a purely arbitrary figure the tollowing relashy

tionships are ass1lJiled to be true

I ____L (9) (i)l72

(10)

For these two values the specific a peed may be combull

putedt

N t Jt VPt (11)8 243

Chapter VI

~RESULTS

A -Pr_e_ae_n_t_a_t_t_o~n g Reaultbull

Graphical presentation ot the results ot this te1t

are given as follows

Figure 17 -Turbine characteristics with 100~ dratt

tuba 1low area

Figure 18 - Turbine characteristics with 7S dratt

tube tlow area

Figure 19 bull Comparison ot power and etticiency at

over gate conditions between 100 and

75~ draft tube flow area

Figure 20 bull COZQparison of power and ettic1ency at

halt gate conditions between 100~ and

7S~ draft tube flow area

Figure 21 bull Comparison of power and etticiency at

over gate condition between 100~ and

So dratt tube tlow area

Figure 22 - Comparison in variation ot apec1t1c

speed between 100 and 75~ dratt tube

tlow area

50

45

20

-bull - 1--shy40

bull J-~ 30

~ ex

~ 20

~~ ~ -)q

I

~ - _

- -

10~ OF DRAFT TUBE FL(Jif AREA

CONSTANT HEAD OF 8l FEST10

POIER OUTPUT EFFICIENCY SPECIFIC SPEED

0 ~--------------_--------~------~------~ 400 600 800 1000 1200 1400

TURBINE SPEED (RPM)

Figure 17 - Turbine Char~cteristics with 100 Draft Tube Flow Area

50

46

-bulllle

~ 7 ~ OF DRAFt TUBE FLOW AREA

0 -~~-rl C05STAMT BEAD OF 81 mET 1J~

POIER OOTPUT ---+- ---o ~_H EFFICIDCY ~ I shy

bull ql SPECIFIC SPEKD - ~ -

bull ~ J 10 L rmiddotr- r- -

bullz- I

~~ 30 ~~--~----~~-

20 ~ ~ middot-shy

26

~~ 25

~0 ~r-----i (

Tbull -bullshy

400 600 800 1000 1200 1400

TURBINE SPEED (R PK )

Figure 18 -Turbine Characteristics with 75 Draft Tube Flow Area

47

EFFICIENCY 60

1-----shy

-~ 50~--~--~~-~middot middot middot middot r~-~----~~~~---4~-r~-~~gtt

II

POWER~ J ~ bull bull

u I

sH

40~------+-------+---- -~~--~~-~~~~

~----~rl 1 bull

I

I

0~--------------~------_------~--------

~ -OVER GATE CONDITION

COIJSTANT HEAD OF 81 FEET

0 o 10~ DRAFt TUBE

_-- _ 7~ DRAFT TUBamp FLON AREA II

10_~-----+--------r-------r----~~

400 600 800 1000 1200 1400

TURBINE SPEED (RPM)

Figure 19 middot - Comparison between 75 and 100 Draft Tube Flow Areas of Power and Efficiency at Over Gate Conshydition

48

t

bull --4 r ~- ~ middot~

70 1-----------+-~~~~~+middot ~ ~~ middot middot -~~--~~--------~~----~-+1

-~-

Atbull bull

lla-

60

amp0

40

20

10

oampOO

t _ - - ~-+- - -~-

l2 GATB COJIDITIOJJ

COJISTABT HJW) OF 81 JBET

o 0 lOQ( DRAFl TUB8 FLOI AREA

e-- - e 75 DRAFT TUBE FLOW AREA

800 1000

- r-

~

TURBIbull SPBIID (RPII)

Figure 20 - Comparison between 75 and 100 Draft Tube Flow Areas of Power and Efficiency at Half Gate Conshydition

49

60

50

-40

bull 30

IIQbull

20

10

0

400

- t - ~

EFFICIENCY

_J bull - bull bull

~ r r middot t -+ shy L -t -

OVER GAD COliDITIOI

CONSTABT BEAD OF 8l FBB

o o 10~ DRAFt TUBE FLOI ADA middot--- 5~ DRAF TUBE FLQPi AREA

600 800 1000 1200

Figure 21 -Comparison between 50~ and 100~ Draft Tube Flow Areas of Power and Efficiency at Ove~ Gate Conshydition

50

25

20

15

10

0

Figure 22

~- T -4 -t- -l --~-

t-~ I

middot --~- t ~---- _ __ _ + --

----~- --r-- --

~-=J-~-=-~ -==~ _ ~- -- ---f---1 - shy

CONSTANT HEAD OF 81 FEBT

o--o 1~ DRAFT TUBE FLltll AREA

75C DRMT TUBK FLCIJ AREAmiddot--middot-middot 600 800 1000

TURBINE SPEED (RPK)

Comparison of Specific Speeds for 75 and 100 Draft Tube Flow Areas

51

B Discussion 2 Result

Consideration of Figures 17 and 18 indicates the

overall eftioi ncy pattern or hill is significantly or

rounded for the 7$~ flow area than for the 100~ flow area

bia implies a greateP efficiency is possible at speeds

leas than or greater than design speed with an insert in

the draft tube However the muilDum efficiency is lemiddotas

Direct comparison at over gate conditions is made in

Figure 19 ~e same general trend is noted tor both the

etticiency and power curves for the 7$~ flow area case

The eurves show higher values at overspeed than do the

correaponding cWvea for the 100 flow area case It ia

not clear whether the curves have been shifted by the dratt

tube constriction or whether the curves simply bulge past

the normal curves at both overspeed and underspeed condishy

tions The power curves apparently peak near the aeme

point bullalthough maximum power is still obtained with the

normal draft tube area

For the comparison at halt gate operation shown in

Figure 20 a general improvement has apparently been made

by restriction of the draft tube flow area At every speed

the etticienoy and the power is greater for the restricted

tlow case The two ett1o1ency curves and two power curvea

are practically parallel throughout the speed range ot

teat

As the flou aroa i e decreased still farther a s1gn1

ticant change appears Reterr1ng to Figllle 211 tor the $0

flow area curves it a obvious that exit losses have

become excessive at the overgate condition because the

efficiency and power are everywhere leas than tor the case

of normal draf t tube area

Earlier it was pointed out t hat 1t the r esult s 1nd1bull

eated an increase in both power and ef tieiency- t hen it

could be assumed tha t the additional los s i ntroduced with

the draft tube insert is less than the diminished losses

due to leas shock losa and water passage losses For the

places where both the efficiency and power have been

increased we can assume that the insert has improved turshy

bine performance

For the places where the power haa been decreased

nothing can be said as to the elimination of ampbock loss

because the new lose present with the drat tube insert has

overshadowed any gains in eftecti Ve head upatJ-eam of the

insert

Near the peak of the efficiency hill howeve~ it may

be pointed out t hat shock loaa ie a minimum with a normal

draft tube and the insert merely adds an additional loss

with the resultant decrease in maximum efficiency tor the

7$~ flow area case

Perhaps the most s1gn1ticant set of eurves is shown aa

53

Figure 22 In this graph values of specific speed tor the

75 and 100~ flow area cases for both over gate and one

halt gate openings are plotted against turbine speed At

every speed and both gate openings the value ot specific

speed for th 75~ flow area case is greater than that for

the 100 t1ow area ease

Since the head is a constant for both situations this

may be interpreted in either of two ways trom equation

(11)

(1) For the same turbine apeed restriction of the

draft tube t1ow area resulted in greater turbine power

(2) For the same power amputput the turbine with 75~

draft tube flow area operated at a greater speed than did

the one with 100 flow area

Since the required diameter of a turbine varies

inversely with the speed the second interpretation could

be stated such that a smaller turbine could be used to

develop the same power output

Whether viewed trom the aspect of increased power

greater speed or reduced size the performance of the turshy

bine with reduced draft tube flow area is superior to that

with the nolmal flow are in the draft tube

The curve of specmiddotific speed versus turbine speed for

the so draft tube flow area case at over gate cond1t1ona

was not included in Figure 22 This curve lies below that

for the 100~ flow area c se at all speeds

In elaboration ot the second interpretation of Figure

22 attention is directed to the relative magnitudes ot

increased apee1f1c speed tor the two gate openings Assumbull

ing that the increase in specific speed implies a shift ot

the power curve to the right along the turbine speed scale

the power curve would be shifted more tor tbe halt gate

opening than tor the over gate opening

It thia trend could be extrapolated to the other gate

openings the tendency can be seen tor the line ot beat

speed to rotate toward the line of the operating speed as

illustrated in FigtU-e ) The advantage of this has already

been discussed

This particular turbine has a low specific speed tor a

reaction turbine Aa the rated value of apecitic apeed tor

reaction turbines increases the line ot beat speed departs

even more radically from the line of operating bullpeed It a

test similar to this were conducted on a reaction turbine

ot gleater specific speed it is pJobable t hat the rotation

ot the line of beat apeed would become more p~onounced

The scheme used in th1a teat had two obvious dr wbull

backs The first was the decision to leave all the wicket

gamiddottes installed tor all conditions ot the draft tube

These gates predominated in control of the tlow The

inserts added to the draft tube merely acted as auxiliary

55

contrGla

The aecond drawback was the choice or device to place

in the draft tube The reasons foll selection of this type

of device have been previously mentioned It is to be

anticipated that adaptation ot dratt tube flow control

would result 1n a better device for an actual turbine

installation Such apparatus might take the form of a

pneumatic bladder or a h7drau11oally operated variable

venturi section in the draft tube It is conceivable that

the gate as used in this test might be adapted also

Chapter VII

OONCLtJSIOfS

From the results of this test the following eonolubull

e1ona aa to the effect ot a variable draft tube flow area

on the performance or a r action turbine may be drawn

(1) The effect ot a variable draft tube tlow area 1a

generally favorable upon the operat1Gn ot a reaction turbull

bine because or the tendency tor the line or beat speed to

rotate toward the line ot operation This resulte in

better performance of the turbine at partbullloads

(2) he etf1o1ency eh111 tor the turbine beeomaa JDore

tlat at the top leading to a smaller max1JilWD effic1enc7

but e reater etticieney at other pointe of operation with

the insertion ot an auxiliary control ror the rate ot tlov

in the draft tube

(3) The power output of the turbine will increase at

over speed over gate conditione as well a at part gate

conditions with the proper amount or draft tube eonatr1cbull

tion or flow

(4) It is possible to eliminate at least partially

eddy type shock loss by tho introduction ot flow control

in the draft tube

BIBLIOGRAPBl

1 Addison Herbert A treatise on applied h-draul1cs New York Wiley 1954 724 Pbull

2 Allen o M and I A Winter middot Co111parative testa on experimental draft tubes Tranaact1ons ot the American ociety ot Civil Engineers 87t893bull970 1924

3 Barrows a E Water power engineering 3d ed ew York McGraw-Bill 1943 791 Pbull

Bovet G A Modern trenda in hydraulic turbine design4middot in Europe Tranaactions of the American Society ot Mechanical Engineera 75975bull993 1953bull

s Oreager William P and Joel D Justin Hydroelectrichandbook 2d ed New York Wiley 19$0 1151 Pbull

6 Daily Jamea w Hydraulic machinery Int Hunter Rouses Engineering hydraulics Hew York Wiley 19$0 p 8$8bull99

Daughertybull Robert L Bydraulie turbines ew Yorkbull7middot MoGrav-Hlll 1920 281 Pbull

8 Daugherty Robert L Inveat1gat1on of tne performance ot a reaction turbine ~anaactiona or the American Society ot Civil Engineers 7811270bull1304 1915

9 Davie L M Model and prototype testa Int Trend in hydraulle turbine practice symposium lranaactions ot the American Society ot Civil Engineers 1o63S3middot368 1941

lfJ Doland James J Hydro power engineering Hew Yorkbull Ronald 1954 209 Pbull

11 Gandy Theodore s and Elmer c Schacht Direct curshyrent motor and generator troubles operation and repair New York McGraw-Bill 1911 293 Pbull

12 Gibaon Arnold H Hydraulics and ita applications5th ed London Constable 1952 813 Pbull

58

13 Button s P Component loases in Kaplan turbinebull and The prediction of efficiency from model tests Probull coedings of the Institution or Mechanical Engineers168743-762 1954

14 Knapp R T~ Oavit t1on mechanics and its relation to the d sign or hydraulic equip ent Proceedings or tne Institution ot Mechanical Engineers 166150bull16) 1952

15 Langsdorf Alexander s Principles of direct curHnt mach1nee 5th ed New York r~cGrawbullH1ll 1940 746 Pbull

16 Lsrner Chester w Characteristica of modern hydraubull lie turbines Trans e~ions of the ~~erican Society ot Civil Engineers 66306-386 1910

17 Linsley Ray K Jr and Jobulleph B Franzin1 Eleshyments of hydraulic enginebullring New York McGrawshyBill 19$5 $82 Pbull

18 Mead Daniel w Hydraulic machinery llev York McGraw-Hill 1933 396 Pbull

19 ead Daniel w Water power engineering New York McGrawbullRill 191S 843 Pbull

20 Mockmore Charles A Part gate operation at water turbines Corvallis Oregon State College Department ot Civil Engineering 1933 11 numb leaves (Unpubshylshed typescript)

21 Mockmore Oharles A Flow characteristics in elbow dratt tubes Transactions of the Amez-ican Society ot Civil Engineers 103402middot464bull 1938

22 Moody L F Hydraulic machinery In c v Davis Handbook ot applied hydraulics New York McGrawshyHlll 1942 1082 Pbull

2) Ptau At-nold Hydrbullulie turbine handbook ld ed Milwaukee AllisbullOhalmers ManufactUIing Company 1948 70 Pbull

RheingalUI w J Recent developments in Francis turshybines Mechanical Engineering 74189-196 1952

25 Russell George E Hydraulica 5th ed New York Henry Holt 1942 466 Pbull

26 Safford A and E P- Hamilton American mixed tlow turbine and ita setting Tranampactions or the Amerieal Society of Civil Engineers 851237bull1)56 1922

27 bull Spannhake W1lhe1Dh Problems or modern pump and tur b1ne design Transactions of the American Society of Mechanical Engineers 56e22$-248 1934bull

28 Sutherlandraquo R A Better ethod or representing and middot tudying water turbine performance ~ansaetions ot thmiddote American Society of Mechanical Engineers 68t675bull 686 1946

29 Teats ot five models or draft tubes tor turbines Engineering News-Record Pbull 182-184 Aug 2 1923

30 White w M American hydztaulic turbines Mechanical Engineering S2t390bull39S 1930bull

31 White w M lhe hydraucGne rega1ner1 its developmentand appl1eat1ons 1n hydroelectric plants Meohanlobulll Engineering 43t37Sbull380 1921 middot

32 Winter I A Economic principlebull in designbull Int Trend in hydraulic urbin practice bull a ampoeiumTranaaot1ona ot the American Society ot Civil Engineerslo6332bull3S2 1941

33 Wiel1cenua G F Fluid mechan1ca or turbo-machineryNev York McGraw-Hill 1947 613 Pbull

APPENDICES

c

Appendix A

NOATIOB

A Angle between the absolute velocity vector and the tangent to the rwmer Subscripts 1 and 2 refel to entrance and exit ot the runner blade

B Angle between the relative 1elooity vector and the tangent to the rwmer Subscripta 1 and 2 refer to entrance and ezit or the runner blade

Angle between the tangent to the runner blade tip and the tangent to the runnel- Subscripts 1 and 2 reter to entrance and exit of the rt1rmer bladebull

Blade angle-gate opening conetant defined by equation (1)

e 09erall efficiency

g Gravitational acceleration assumed constant at 322 teet per second per second bull

H Turbine head detined by equation ($)

m Exit loss coeft1e1ent

Turbine speed expressed in revolutions per minute

Turbine speed under a constant head of 81 teet

specitic apeed of the turbine under a constant head ot 81 teet

p Power output in horsepower ot the tvbine

Power output of the turbine Ulder a constant head ot Sl teet

Pl- Pressure head at entrance to the tUlb1new

l1 Peripheral velocity ot the runneP Subacr1pta 1 and 2 refer to entrance and exit ot the JUnllampr blade

62

v Relative velocity reaulting trom the combination ot the absolute water velocity V and the runner periphshyeral velocity u Subscripts 1 and 2 refer to entrance and exit ot the runner blade

v] Relative velocity vector necessary to produce a tanbull gential entry into the runner blades

V Absolute water velocity Subscripts l and 2 refer to entrano and exit ot the runner blade

v2 Velocity head Subscripts 1 and 4 reter to the ~8 entrance to the turbine and the tail~ace wate~

w Unit weight ot water assumed constant at 624 pounda per cubic toot

V Weight rate ot flow in pounds per aeooncl

XX Velocity component ot ahook See Figule 2

Z Elevation head Subscripts 1 and 4 reter to entrance to the turbine and the taibace water surfacebull

Appendix B ORIGINAL DATA-Run

lfwnber

0-4-1 0-4-2 0-4-3 o-4-4 o-4-S o-4-6 0-4-7 0-4-8 0-4-9o-4-lo o-4-11 o-4-12 0-4-13

o-6-1 o-6-2 06-3 o-6-4o-6middotS o-6-6 o-6-7 o-6-8 0-6-9 o--6-lo o-6-11

Speed

rmiddot2middotbullmiddot(1)

336 38$ 451 S$9 620 669 6lt)$ 120 787 860 932

102imiddot109 bull

352 355 443middot 543middot 620 654AJs32

911 1001 1111

~essure Head rt (2)

410 410 416 426 431 43-7 439 44-9 452 467 482 soo $1 bull $

350 351 35middot7 )66 37-9 37-9 392 41 bull 3 43middot3 460 489

Elevation Bead

fjj $7 $7 $7 $7 $7 $7 51 57 5-15858 $8 58 56 56 $6565656 51 575As5a

Velocit Head

flj 07 07 07 06 06 06 06 os 05 os0404 03

09 09 oa o8 o8 os 07 07 06 o~o

Total Head rt ($)

47middot4 4A44 o 489 49-4 soo $02 $11 $14 $29 5imiddot45 2 576

41 bull $ 416 421 430 44middot3 44middot3 456 47-7 496 523551

Plow

lbtjec

326 324middot317 311 306 30029middot28 middotmiddot middot 386 275middot260 240 218

359 36~35 bull 349 345middot 339 330 318 300 273 240

Line Potential

vyqjbull 1060 1220 ~-0o 1920 2150 2000 2$60 2000 1940 18)015io11 o

1000 1100 139bull5 1760 1925 16$0 1620 1610 1540 1330 870

Line Current

amlscs 960 900 830 740 730655 70bull 0 530 660 600 5imiddot54 6 )60

982 930 860 780 ~3-545

79-5 74-5 670 560 370

P

Appendix B ORIGINAL DATA (Continued)

Run Number

Speed

Pbulltmiddotbullmiddot )

leasure Head ft(2

Elevation Head tt(J)

Velocity He-dfmiddotj

Total Bead tt($

Flow

lbstsec( )

Line Potential vo~ta( )

Line Current

amjs (sect

0bulllt)-1 0-9-2

3ll6 398

28o ~~1

$6 56

1o 10

346 347

390 365

1ooo 1190

aao 835

0-9-3 0-9-4 o-9-S

472 565 632

292 305 312

$6 s6 56

10 o9 o9

)$8 J7~o 37~7

381376 37o

1)6614oo 141o

820 ass ass o-9-6 0-9-7 0-9-8 o-9-9 0middot9-10

680 120 762 844 920

)24337346 366 390

56 $6 56 57 $7

09 os o8 oa 07

)89401 410 431454

367~ 357348 34o 322

1400 1J6o l36o 1310 1170

843 820 7957So 67~0

0-9-ll 0-912

1001 1100

41 bull 7 45-3

s 7 6~0

06 os 480 $18

299 268

980 65$

560 36~5

1-4-1 1-4-21-4-l1-4shy1-4-5 1-4-6 l-4-7 1 4-8 1-4-9 1-4-10 1middot4-ll 1-4bull12

354middot452 562 62q 674shy102 752 760- 863 932

1022 1100-

)82389 4014oa 416 41--7 423 428 44-2 45-7 486 49-2

51S757 51 5-7 5middot15zs sa $8 58 59

07 07 06 06 06 06 06 os o bull o 04 o J

446 45-)46middot4 471 ti7-9480 q86 491505 $19 548 55-4

)28 320 311 306 300 295 291 286 269 2582iimiddot21 bull

1080 14Lo 1550 153-5 1470 141-0 1385 1310 1310 1230 1120 855

970855 875 91-0 94~0 975 966 995 860 77-S 610 4fo

0 ~

Appendix B ORIGINAL DATA (Contirmed)-Run Speed Pressure Elevation Velocity Total Flow Line Line

Number Head Head Head had Potential Current rtjjmbull t~ bttec vyfs am~a12) ( ) ti fli 8

1-6-l $6 33$ $6 0bull9 400 364 1100 93 0 1-6-2 41 34laquo2 $6 oa 406 JS7middot iios a5s l-6-3 500 3~0 5bull6 os 356 1 1 o aos 41middot~1-6~4 35bull4 5-6 oa 41middot 352 16~0 82 0 5~1-6-5 5 bull 36_2 Sbull6 08 42bull6 349middot 161 ~ 0 86~0 1-6-6 622 366 $6 oe 43bull0 345middot 158 0 88~$ 16-A 649bull 37bull1 56 os 43-S 342middot 1570 895 1~- 386 57 07 46-0 192 ) 125A44 333middot 1-6-9 3) 404 5middot1 07 468 317 1620 675 1610 911 42-4 5-7 o6 48-7 298 168 0 61 0 1-6-11 999 451 56 os Sl ll 276 ~2-0 530 1-612 1115 485 58 04 54middot7 238 90 )3 0

1middot9-l 355 279 56 10 )45 385 1040 870 1-9-2 399 28J $6 10 )49 38$ 1140 86 5 l-9-3 ~ ao 291 56 ~0 35middot1 J8J_ JJ6o 815 1bull9-4 579 303 56 09 )68 375middot J4JO 830 l-9bullS 40- 313 )6 09 31middot8 370- 1460 82~0 1-9bull6 679 2) 56 09 3 bull8 364middot 1670 710 l-9-7 682 319 56 o9 384 ) 62 1460 79 5 l-9-8 724 33middot5 56 o8 399 3$6 bull 1480 76 -5 1-9-9 762 34middot3 $6 0 bull 8 407 )48 14910 13middotS 1-9-10 833middot )60 5middot7 os 42$ 339 144$ 686 1-9-ll 926 39middot1 5-7 07 455 318 1290 600 1-9-12 1000 41middot3 0-6 476 298 1115 510$ ~ 1middot9-13 1105 452 s o4 $14 2$6 710 )10

~

Appendix Bt ORIGDIAL J (Continued)

Run Speed Pressure Elevation Velocity Total Plow Line Line Number Head ltead Head jlamp$d P()ten~ibulll Current

r~~~m ft ft lbs~seo voltattj rgj twimiddot t 1 t2gt lt3 ou t ( rt

2-9-1 384 289 S 6 10 35 5 1400 1170 810 2-9-2 443middot 29$ $6 ltimiddot9 360 379middot 11(0 87$ 2-9-J 536 30bull 3 sc 09 )68 374middot 1)40 84 bull) 2-9-4 571 306 $6 09 3~1 372 120bull 0 955 2-9-5 623 316 S6 09 J l )6S UJSo 77$ 2bull9-6 669 327 S6 09 )92 )61 1240 905 2-9bull7 712 )39 56 os 40-3 351 12(0 86 bull0 2-9-8 ~5$~ J48 56 oa 412 348 1290 81 bull ) 2-9-9 04 )63 56 oa 42-7 339 12ltJO 76$ 2middotmiddot9-10 8$2 376 5middot1 07 440 33~- ~ o 710 2-9-11 955 394 5-1 o6 457 300 1100 506 2middot9-12 1000 421 $7 06 48middoti 295 1020 $18 2-9bull13 110~ 463 56 05 $2 267 620 3~0

oshy0

Appendix Gt CALCULATED DAgA

Turbine Run Generator Generator Turbine Turbine Efficiency Turbine Turbine Specit1c

Number OutputKWlt21

Loa~Jes KWlol

Outut K bull (H)

Input RP 12)

middot Percentlt13gt

Speed r~Jmiddot(

0ltput HP ~1

Speed r-m

( 6) middot

o-4-1 0middot4-2 0-4-3 0-4-4 0-4-5 0-4-6 O-qmiddot7o-4-8o-4-9 0-4bull10 0-4-11 o-4-12

1018 1o9a 1220 1)62J40214oa1J4oo 1357 1320 1164 997 718

046 o59 071 092 096 1071oo 134 104 100 109 107

14261sso 17)01948 2008 20322011 1999 19 09 1708 14-84 11o6

281279 27-7 276 215 273271 268 268 26h 258 24-5

soa 555 62$ 705 7)1145 742 74-6714645 51s 45-1

440 sos 585 720 195 sso sao 9$$ 985

1065 1135middot 1230

318 357 319 416 422 419412 39middot9 378 324 260 191

102 12bull4 148 191 21bull 3 22o 233 249 24924middot9 238 221

0-4middot13 418 104 699 228 306 1300 117 18)

o-6-1 982 045 1376 271 $08 496 376 124 o-6-2 o-6-3 G-6-4o-6-5 0-6-6

1023 1200 13 73 J415 139h

051 0middot66 oaa ()bull 96 088

14-39 1696 1958 2026 1986

276 27middot4 273 278 274

$20 61 8 717 7)0726

q95615745 8)5685

390 ll5middot3 sos soo 490

127 170 218 243 2$$

o-6-7 o-6-8 o-6-9o-6-lo

1288 1199 1032 7-45

o9o 094 09$ 096

1846 1733 1511 1128

274 276 271 260

67S 629559 43middot4

980 1085 1165 1245shy

436 )83316 21bull 7

266 276 270 239

0-6-11 322 1oo 566 2141 2JS 1350 101 177 0 --4

Appendix C CALCULATED DAlA ( Continued)-Run

Number Generator Generator

Out2ut Losaes xw LW- 12gt (lO)

Turbine Out2ut

ltPlJ

Turbine Inat lfP Jig)

Etpound1e1ency

PireentDl

Turbine Sed x-~m( 1

Turbine OutEut RPJl)

Turbine Specific

SeeedrIbullntbull

( 6)

o-9middot1 0-9-2 0-9-3 o-lt)-4 09-$ 0bull9-6 0-9-7 0-9-8 0-9-9 0-9-10 o-9-11 0-9-12

aao 994

111$ 1197 1206 1180 11)21081 982 784 5-49 2)9

0middot45oss o6$ 070 07$ 0-77 (l77 or~ o s06o 8 096

123~ 1402 1$80 1698 17bulllS 168$ 16bull18 ~middot5430 1151 a~J4 9

24middotgt24middot3248 25~25 260 260 259 267 266 26middot1 2S2

sos 577 63-7 671 676 650 621 60036J4

327 178

$) 610AlO 3$

92S 980

102$ 1070 1157middot 1230 1300 137Smiddot

44middot4 soo 523 ssomiddot 540so6 46-5 432 368 274 18~8

J46 176 21-1 255 2802s_A 28 289 288 265 231 168

1-4-1 1-4middot2 1-4-3 1-4-4 1-4-5 1-4-6 1-4-7 1-J-8 1-4~9 1-4-10 1-4-11 1-4-12

10bull48 1231 13-S6 1397 1)821375 1))8 1303 1127 953 683) 51

048 067 o7A07 0 bull79 oa1 oss o bullao osa 0lt)0 096 099

J468 1740 1921 1978 1958 19$1 1911 lSSi162 1)98 1045

603

266 264 262 262 261 2512$7 2$6 24middot7 24-3 233 217

551 660 13middot3155 75-6 7~-97 middot4 72$ 67 51middotJ 44middot9 21middot1

475 605 A4220

875middot 910 970_

1000 1090bull 1166 1243 1330

5816

44middot444middot5 430 427 412 392 329 273 188 l0-7

117 101 204 22$ 2)7245 2562sa 257251 222 179

a-C))

Appendix Ct CALCULATED -DATA ( Ocntinued)

1-6middot1 1023 o$2 14-41 26S 505 41~6 26~

54middot5 13middot3l-6-2 1201 067 1boo 625 47-9 17shy~middot41-6bull3 1296 oA9 1 middot43 26 9 700 so5 20bull 4 l-6-4 l3j5 o 0 19~09 268 71bull3 A5o 514 222 1-6-5 1) 5 o81 19(gt4 271 725 51-5 238 l-66 1398 081 198) 27-0 736 8 S13 252~-middot l-6j 1405 083 199i 211 733 885 $middot06 2$9 l-6 13middot9~ 103 2amp 0 279 71 8 985~ 467 ~-69 1228 1 bull 02 17-SS 270 661 109$ 407 ~3~ l-6bull10 1025 100 lSll 26i 573 1175middot 27~S32middot~l-ampu 153 1-00 llft3 26 444 1270 22 24bull8 1bull6-12 294 100 52a 231 22 3 1360 95 172

1-9bull1 904 048 1275 2J4Z $28 S4$ 459 1$2 1-92 98$ oss 13-92 24middot4 57-0 6JO 49bull1 176 1-9middot3 1110 066 1$76 24middot9 63middot4 I2o 536 21-7 l--9-4 1187 072 1685 251 66$ 5 $$ bull 0 261 1middot9-5 llltJ7 1710 25middot4 67-3 93$ 536 28~20-671middot9-6 1186 o 8 1708 25-7 67) 980 $15 2691-9- 1161 oBo 1660 2$middot3 6$6 990 508 29-1 l~- ll-32 oB) 16sect0 2$8 632 1030 471 291 1-9bull9 109$ oa5 2$7 614 1075 29S~middot 0 4imiddot41-9-10 9~91 oas 262 S$1 1150~ 3 o 292 1-9-11 o9o u57 12JiO 21gt 26-77middot74

-45 26sect ~middot91-912 $69 091 sas 25 middot3 1)0$ 196 2J-8 1-9-1) 220 098 426 2)9 178 1390middot 84 16 6

0 0

Appendx C CALCULATED DATA (Continued)

Turbine Run Generator Generator lurbine Turbine Eft1e1eney Turbine lurbine Spee1f1c

Number Output Losses Outit Input Speed Output SPed middot k_-V KW R _ H_bull_P Percent r Thm HP rpm_ (9) tlo) 11) middot (12 _) (lJI ( ) (1$ (14)

2-9-1 9--46 055 1)62 258 528 580 164 2-9-2 1024 056 248 58 4 665 4 9 191iimiddot48 4~middot0 2-9-3 1132 067 05 2$0 641 795 52q 237 2-9-4 1148 065 1027 2$1 -~8 845 525 252 2-9-5 11 77 oso 16-83 253 6 910~ 522 270 2-9 6 1122 071 1600 251 622 960 47-5 2722-9-A 1092 015 1562 257 608 1010 445 2z12bull9- 1052 079 1514 261 580 1060 41middot7 2 2 2middot9-9 986 o82 ]429 26) 542 1105 372 277 2-9-10 915 086 1340 268 500 1160 334 27-6 2-9-11 638 087 972 254 )81 1270~ 229 250 2-9-12 )28 090 828 259 )19 1295 179 226 2-9-13 192 094 383 2$ 6 150 1370 7 3 152

-3 0

Page 28: The Effect of A Variable Draft Tube Flow Area on the

21

22

(2 peat (l) with the gate installed in the drat

tube

(3) middot Converting middot all data to a constant head compare the

powere and effioiencies at the same wicket gate setting and

turbin speed tor the two cbullses

If the ddition or the gate indicates an improvement

in power output and efficiency and the powe~ curve shifts

to the right along the turbine apeed scale the advantage

ot draft tube con~ol of the flow will hav been demonshy

strated

Chapter IV

A E9J11pment

ih turbine used in this test is lJ 5 1nch Pelton

reaction turbine with a rated output ot 30 horsepower under

a head of 56 feet at a speed ot 720 reYolutiona per minute

Views of this turbine are hovn in Figures S and 6 The

turbine is installed on a concrete pad located over an open

channel in the Hydraulics Laboratory at Oregon State Colshy

lege The date of manufacture of this turbine was 1915

The water was delivered to the turbine from a sump

reservoir by two pumps operating 1n parallel Each pump 1a

an 8 inch Pelton double suction centrifugal pump witb a

rating of l$00 gallons per minute at a head ot 75 teet with

a speed ot 1175 revolutions per minute Tbe inlet tlange

ot tne turbine is $pprox1mately 18 feet above the center

line of the pump

A direct current generator was coupled to the turbine

to receive tne power d veloped as shown in Figures 4 and 7 The generator is a Spr gue Electrodynamometer rated at SS horsepower with a speed range of 7$0 to l$00 revolut1one

per minute The classification is type LO 26A 2)0 volta

Figure 5 - View of Test Turbine

Figure 6 ~ View of Test Turbine

and 149 amperes lbe generator ti ld was aepar tely

excited using direct current from a motor g n r tor ampt

(l$ p 4~8)

The power output of the generator waa dissipated in

the water rheostat (3 p 488-489) shown in Figures 9 and

10 The galvanized tank contain d water ot variable d pth

on an electrode ot cast iron m aauring 1bull x 1 x 1

In the initial installation of the turbine it was

intended that the power output should be measured with a

Prony brak bull For th purpoa68 or this teat it was decided

that the brake was too instable and the generator was

substituted The platform for raising the generator the

nee asary two teet for alignment was built out of available

material In this case heavy laminated wood blocks reiashy

torced with other timbers were used and bolted through the

concrete deck (11 Pbull 36-$7)

Due to the light concrete deck the lack ot mas in

the platform and the slight misalignment in the flexible

coupling ao e vibration waa encountered It seemed to

ncr aae linearly to a maximum at the speed of bout 750

revolutions per minute Above this speed no vibPation was

noticeable The vibration waa not se~ere and does not

appear to have materially affected the test results

26

B Intrumentat1on ~ eaeur1ng Devices

The pressure head at inlet to the turbine vaa meaave4

bymeane ot two )6 inch waterbullmeroury manometerbull connected

in series as shown in Figure 8

The terminal voltage ot the generator vas meaeured by

a laboratory voltDleter with a range to )00 yolta and callbull

brated to within 15 Yolta

The armature current bull and hence the line current was

measured by a laboratory ammeter with a range to 150 amperea

and callbrated to w1 thin o 7S amperes

Tae rate ot tlow was established by weight and time

meaeurementa The weighing ank has a capacity ot 121 000

poundsJ the weight belng indicated by Toledo direct reading

scales Timing was done with a hand atop watch with clivibull

aion ot 02 second

he ~ater level in the tailrace was dete~1ned by a

hook gauge lhie was read to the nearest 001 toot

The turbine and generator speeds were eaaured by a

hand tachometer The technique of almost cont1nuoua readbull

ings of the speed gave an error ot no more than 5 revolubull

tiona per minute

c Operational Procedure

Atter the water level in the aump was checked to

insure an adequate auppl7 the puapa were primed and

27

Figure 7 - Test Generator and Plattorm

Figure middot8- Instrument Board and Field Rheostat

28

started After venting they were valved for operation 1n

parallel

The motor generator set was started to supply the

field current and the circuit breaker was closed Water

wa added to the water rheostat to the level shown in

Figure 10 ~ field current wae minimized by cutting in

all the f ield resistance in the field rheostat of Figure 8

The l2 inch gate valve shown in Figures 5 and 6 waa

slowly opened and the turbine and generator brought up to

speed The 12 inch gat valve and turbine were vented and

the pumps were checked to insure neither had lost ita prime

lhe water rheostat offers very steady load 1f the

water level is essentially constant and the water temperabull

ture 1a fixed () p 488~89) In order to maintain this

constant temperature it was decided not to circulate the

water in the rheostat but rather to allow the water to

boil thua achieving the desired result A standing wave

was set up on the face ot the electrode by the boiling

action but a atable load was eatablished except at very

low water leYels where th11 agitation led to fluctuationa

in the line current

After putting the turbine and generator on the line

maximum power was dissipated in the rheostat by redueing

the turbine speed to between oSO and Soo revolutions per

minute Salt vas added to the rheoetat wat r to increasemiddot

29

Figure 9 - View of Water Rheostat

Figure 10 - View of Water Rheostat

Separate Field ExcitationFrom Motor-Generator set Compound Water-Mercury

---shy

re Manometer

I Q)

~ 0

~

Book Gauge

Open Channel

I

Slap Reservoir

Figure 11 - Wat~r Flow Diagram and Electrical Layout

31

waiting pe~iod ot perhaps an h~ followed

while the boiling point or the water wbulls reacbe4 During

this ti+ne the manometer was vented end eheoked electrical

measur1ng 1nstlUments were connected end the hook gauge was

adjusted tor elevation

It required about two- houtte tor the generator to reach

its normal operating tempe-ratu~e_ After the water in the

rheostat and generator had reached their operating temperabull

turea it was possible to begin the taking of data

The only vaPiable which was controlled wee the turbineshy

generator speed However the upper l1ut1t of safe line

current was slightly over 100 ampJilPampPes and the eireuit

breaker would open when the current reached lOS ~ere bull

Control was exercised by means ot regulating the water

level and salt 1n the water rheo tat and the res1stsnoe of

the tield rheost t~

The etfeet ot each type ot regulation on the three

variables is shown below

Volta Aaperebull Speed

Inc Dec Inc Dee~ Inc Dec

Wa~e1 Level Inc Dec~ X

X X X X

X

Salt Concentration

Inc Dec X

X X X X

X

field Resistance

Inc Dec

X X

X X

X X

32

Jlot all methods gave the ame amount ot change in a

given variable and a period of experiment and trial led to

the following scheme starting the rune with the lowest

turbine speed the water level was high with a high amount

ot salt and the field resistance was cut completely out

Aa it became necessary to increase the speed tor each

aucceasive run either cutting in t he field resistance

decreasing the salt concentration or lowering the Vater

level would produce the desired result However decreasbull

1ng the salt concentration had to be done Without a net

gain in water which led to a tluahing procedure that was

not particularly good because cold water was introduced

which required time to heat to the boiling point Cutting

1n additional field resistance was a good method but th1a

increased the amperage possibly to the point of opening

the circuit breaker Lowering the water level was aatiashy

factol1 until the level got too low causing the current

fluctuation previously mentioned Actually it turned out

that a combination of lowering the water level and cutting

field resistance in would carry the speed from ita minimum

to 1ts maximum value it the proper choice were made each

time the speed waa to be changed At the conclusion of

each aet of runs at a high speed the water level would be

low and the field resistance high

33

TURBINE

PAD AND DECK

TAILRACE

WATER SURFACamp

CONCRETE

DRAFT TU1B INSERTS

7 5( DRAFr TUBE

FLltJI ARIA

5~ DRAFT TUBE

FLOI ARSA

Figure 12 - Sketch of Draft Tube and Test Inserts

34

Figure 13 - View of Draft Tube Insert

Figure 14 - View of Draft Tube Insert

D c __ ~s_middot hedu_le of

A number was assigned to each run The fi~st number

applies to the draft tube tlow areas

1 bull 100~ flow area or 0~ oonatriction

2 - 7S tlow area or 2$ conatr1ct1on

3 SoC flow area or so~ constriction

The second number refers to the wicket gate openings

9 over gate opening

6 bull intermediate gate opening

4 bull one h lt gate opening

The third number 14entif1ea the location of the particular

1Wl in a set ot rona made at a given dratt tube tlow area

and wicket gate opening

fnua run number 1bull4bull10 would identity this as the

tenth run ot a set made at halt gate with 75 ot the draft

tube t1ow area

Rune w re made tor a g1yen dratt tube condition

Firat tor tull 41-aft tube flow area seta ot rune were

made for the overgate halt gate and intermediate gate

conditione An insert was placed in t he draft tube and

rune based on the same gate conditions were made tor the

7S~ draft tube flow area case The insert was then changed

to allow only $~ draft tube flow area

The inserts are sketched 1n Figure 12 and photographed

ln Flgurea 13 and 14 They oonaisted of circula~ segments

36

or l2 ineh plywood mount 4 on wooden legs 10 inches high

The 1nse7te were placed in position and secured by th use

ot a-clamps on the legs and the outside ot the bottom of

the draft tube The obvious disadvantage to this method

waa the neoeasity tor draining the water from the tailrace

tor a change ot 1naert The advantage vas of course the

simplicity ot design and construction

Chapter V

DATA-A Original Data

The normal data-taking crew consisted or two men

Assuming adjustments having been made to secure a certain

turbine speed (aee section on Operational Procedure) one

man would take semi-continuous speed readings with the hand

tachometer until a state or rotational equilibrium was

reached This could be only a period or two minutes up to

ten or tifteen minutes As soon as steady speed was

assured the data taking would begin The second man went

to the weighing tank Where a minimum ot three weighingamp

were made The requirement was to get three consecutive

readings such that the ditterence between tbe smallest and

largest time did not exceed 04 seconds The time to

collect a given weight ot water was then assumed to be the

arithmetic average of the three times He then went to the

hook gauge determined the hook elevation and then

recorded the data on the data sheets The first man meanshy

while had taken readings of the line voltage line current

and manometers and checked the turbine speed by multiple

readings During the length of the run all values were

38

checked to determine mean values for recording

The minimum length of one run was about five minutes

If one or more measure ants tended to drift during the run

all values wer discarded and a new run began as soon aa

qu111br1um was stabl1shedo

B -0-al_e_u_l_a_t--d Data

The h d on the tu~bine 1 defined by

($)

The maxtmwm velocity V4 was equal to about o8 tampet per

secon4 which makes it a negligible quantity when converted

into velocity head

An engineerbulla level was used to deterine the d1ffePshy

ence 1n elevation between the compound water-mercury manoshy

meter and the hook gauge Using this value the equation

for turbine bead becomes

where z4 is the hook gauge reading

The rate of flow 1 cent

w weight or water collected average time to collect

The inlet velocity v1 vas calculated by dividing the

weight rate or flow by the specific weight of water and the

)9

area ot ~e inlet pipe This was equivalent to dividing

the weight rate of flow by 490 Then the power input to the turbine is equal to

WHpin rri

10 (6)

Also

(P ~ut) Turbine

(P out) + Generator

(P lost) Generator

The power output of the generator is simplJ the

produot ot the terminal voltage and the armature (line)

curPent The power lost in the generator can be subdivided

into copper losses and stray power losses lo evaluate

these cunes based on losses of an identical generator

11leampsured by the Department ot Mechanical Engineering were

used The loss curves are reppoduced in part in Figures

15 and 16

Determination ot generator losses proceeds as tollowau

(1) From Figure 15 detem1ne the vo1tage drop in the

armature circuit using the temperatures of 1220 F and the

meaaured current

(2) The induced voltage is t~e sum of the terminal

voltage and the voltage drop 1n the armature circuit

() Entering the induced voltage and the turbine speed

into Figure 16 the stray power loss can be determined

(4) The copper lose can be evaluated from Figure 1$

using the measured current and the temperatlll-e of 1220 P

40

25 ~------~--------~--------~------~

U) -U) - 20

f-4 ~

-~ -gt 0

0

VOLTAGE DROP

~ - i -

- bullbullbull bull - -middot-middot -+ ~- + -t--+ ~ - ~ middotbull ~-~ middott- -+----- _ -4 middotmiddot- --~-+-t---r~~ ~--+t-t- - ---t-c-++~-ulf--

0 50 75 100

Figure 15 - Curves of Generator Voltage Drop and Copper Loss

41

1200

1000

800

600

800

0

0

~-

middot--~ 1shy --1 + bull l

100

I -

150 200

IIDOOED VOLTAGB (VOLTS)

Figure 16 - Curves of Generator Stray Power Loss

_ j

-bullshy -L---- shy middot -shy

250

- r

42

(5) The generator los os equal the sum of the eopp r

loss and stray power loss

~e efficiency or the turbine is taken as

etticiency u e =P out (8)Pin

~ample pound Determ1n1gg turbine Power Output

The following data are taken trom that ot Run 1-9-1

Line voltage 1040 volts Line current 870 amperesSpeed 355 revolutions per minute

The induced voltage 1a determined as follows

Line voltage 1040

Voltage drop 90 using Figure 15 with line current of 870 amperes and temperature ot 122 degrees)

Induced Toltage 1130 volta

The power output of the turbine is determined as follows

Generator output 90$0 (line voltage z line current)

Oopper loss 7 (using Figure 15 with line current of 870 amperes and temperatUe or 122 degrees)

Stray power lose 470 (using Figure 16 with speed ot 355 revolutions per miDUte and induced voltage or 1130 volts)

Turbine power output 9527 vatta

or turbine power output 1s 12z2 horsepower

43

The conversion of the calculated data to a constant

head is based on the conventional assumption of constant

efficiency regardless of turbine head For a constant head

ot 81 teet a purely arbitrary figure the tollowing relashy

tionships are ass1lJiled to be true

I ____L (9) (i)l72

(10)

For these two values the specific a peed may be combull

putedt

N t Jt VPt (11)8 243

Chapter VI

~RESULTS

A -Pr_e_ae_n_t_a_t_t_o~n g Reaultbull

Graphical presentation ot the results ot this te1t

are given as follows

Figure 17 -Turbine characteristics with 100~ dratt

tuba 1low area

Figure 18 - Turbine characteristics with 7S dratt

tube tlow area

Figure 19 bull Comparison ot power and etticiency at

over gate conditions between 100 and

75~ draft tube flow area

Figure 20 bull COZQparison of power and ettic1ency at

halt gate conditions between 100~ and

7S~ draft tube flow area

Figure 21 bull Comparison of power and etticiency at

over gate condition between 100~ and

So dratt tube tlow area

Figure 22 - Comparison in variation ot apec1t1c

speed between 100 and 75~ dratt tube

tlow area

50

45

20

-bull - 1--shy40

bull J-~ 30

~ ex

~ 20

~~ ~ -)q

I

~ - _

- -

10~ OF DRAFT TUBE FL(Jif AREA

CONSTANT HEAD OF 8l FEST10

POIER OUTPUT EFFICIENCY SPECIFIC SPEED

0 ~--------------_--------~------~------~ 400 600 800 1000 1200 1400

TURBINE SPEED (RPM)

Figure 17 - Turbine Char~cteristics with 100 Draft Tube Flow Area

50

46

-bulllle

~ 7 ~ OF DRAFt TUBE FLOW AREA

0 -~~-rl C05STAMT BEAD OF 81 mET 1J~

POIER OOTPUT ---+- ---o ~_H EFFICIDCY ~ I shy

bull ql SPECIFIC SPEKD - ~ -

bull ~ J 10 L rmiddotr- r- -

bullz- I

~~ 30 ~~--~----~~-

20 ~ ~ middot-shy

26

~~ 25

~0 ~r-----i (

Tbull -bullshy

400 600 800 1000 1200 1400

TURBINE SPEED (R PK )

Figure 18 -Turbine Characteristics with 75 Draft Tube Flow Area

47

EFFICIENCY 60

1-----shy

-~ 50~--~--~~-~middot middot middot middot r~-~----~~~~---4~-r~-~~gtt

II

POWER~ J ~ bull bull

u I

sH

40~------+-------+---- -~~--~~-~~~~

~----~rl 1 bull

I

I

0~--------------~------_------~--------

~ -OVER GATE CONDITION

COIJSTANT HEAD OF 81 FEET

0 o 10~ DRAFt TUBE

_-- _ 7~ DRAFT TUBamp FLON AREA II

10_~-----+--------r-------r----~~

400 600 800 1000 1200 1400

TURBINE SPEED (RPM)

Figure 19 middot - Comparison between 75 and 100 Draft Tube Flow Areas of Power and Efficiency at Over Gate Conshydition

48

t

bull --4 r ~- ~ middot~

70 1-----------+-~~~~~+middot ~ ~~ middot middot -~~--~~--------~~----~-+1

-~-

Atbull bull

lla-

60

amp0

40

20

10

oampOO

t _ - - ~-+- - -~-

l2 GATB COJIDITIOJJ

COJISTABT HJW) OF 81 JBET

o 0 lOQ( DRAFl TUB8 FLOI AREA

e-- - e 75 DRAFT TUBE FLOW AREA

800 1000

- r-

~

TURBIbull SPBIID (RPII)

Figure 20 - Comparison between 75 and 100 Draft Tube Flow Areas of Power and Efficiency at Half Gate Conshydition

49

60

50

-40

bull 30

IIQbull

20

10

0

400

- t - ~

EFFICIENCY

_J bull - bull bull

~ r r middot t -+ shy L -t -

OVER GAD COliDITIOI

CONSTABT BEAD OF 8l FBB

o o 10~ DRAFt TUBE FLOI ADA middot--- 5~ DRAF TUBE FLQPi AREA

600 800 1000 1200

Figure 21 -Comparison between 50~ and 100~ Draft Tube Flow Areas of Power and Efficiency at Ove~ Gate Conshydition

50

25

20

15

10

0

Figure 22

~- T -4 -t- -l --~-

t-~ I

middot --~- t ~---- _ __ _ + --

----~- --r-- --

~-=J-~-=-~ -==~ _ ~- -- ---f---1 - shy

CONSTANT HEAD OF 81 FEBT

o--o 1~ DRAFT TUBE FLltll AREA

75C DRMT TUBK FLCIJ AREAmiddot--middot-middot 600 800 1000

TURBINE SPEED (RPK)

Comparison of Specific Speeds for 75 and 100 Draft Tube Flow Areas

51

B Discussion 2 Result

Consideration of Figures 17 and 18 indicates the

overall eftioi ncy pattern or hill is significantly or

rounded for the 7$~ flow area than for the 100~ flow area

bia implies a greateP efficiency is possible at speeds

leas than or greater than design speed with an insert in

the draft tube However the muilDum efficiency is lemiddotas

Direct comparison at over gate conditions is made in

Figure 19 ~e same general trend is noted tor both the

etticiency and power curves for the 7$~ flow area case

The eurves show higher values at overspeed than do the

correaponding cWvea for the 100 flow area case It ia

not clear whether the curves have been shifted by the dratt

tube constriction or whether the curves simply bulge past

the normal curves at both overspeed and underspeed condishy

tions The power curves apparently peak near the aeme

point bullalthough maximum power is still obtained with the

normal draft tube area

For the comparison at halt gate operation shown in

Figure 20 a general improvement has apparently been made

by restriction of the draft tube flow area At every speed

the etticienoy and the power is greater for the restricted

tlow case The two ett1o1ency curves and two power curvea

are practically parallel throughout the speed range ot

teat

As the flou aroa i e decreased still farther a s1gn1

ticant change appears Reterr1ng to Figllle 211 tor the $0

flow area curves it a obvious that exit losses have

become excessive at the overgate condition because the

efficiency and power are everywhere leas than tor the case

of normal draf t tube area

Earlier it was pointed out t hat 1t the r esult s 1nd1bull

eated an increase in both power and ef tieiency- t hen it

could be assumed tha t the additional los s i ntroduced with

the draft tube insert is less than the diminished losses

due to leas shock losa and water passage losses For the

places where both the efficiency and power have been

increased we can assume that the insert has improved turshy

bine performance

For the places where the power haa been decreased

nothing can be said as to the elimination of ampbock loss

because the new lose present with the drat tube insert has

overshadowed any gains in eftecti Ve head upatJ-eam of the

insert

Near the peak of the efficiency hill howeve~ it may

be pointed out t hat shock loaa ie a minimum with a normal

draft tube and the insert merely adds an additional loss

with the resultant decrease in maximum efficiency tor the

7$~ flow area case

Perhaps the most s1gn1ticant set of eurves is shown aa

53

Figure 22 In this graph values of specific speed tor the

75 and 100~ flow area cases for both over gate and one

halt gate openings are plotted against turbine speed At

every speed and both gate openings the value ot specific

speed for th 75~ flow area case is greater than that for

the 100 t1ow area ease

Since the head is a constant for both situations this

may be interpreted in either of two ways trom equation

(11)

(1) For the same turbine apeed restriction of the

draft tube t1ow area resulted in greater turbine power

(2) For the same power amputput the turbine with 75~

draft tube flow area operated at a greater speed than did

the one with 100 flow area

Since the required diameter of a turbine varies

inversely with the speed the second interpretation could

be stated such that a smaller turbine could be used to

develop the same power output

Whether viewed trom the aspect of increased power

greater speed or reduced size the performance of the turshy

bine with reduced draft tube flow area is superior to that

with the nolmal flow are in the draft tube

The curve of specmiddotific speed versus turbine speed for

the so draft tube flow area case at over gate cond1t1ona

was not included in Figure 22 This curve lies below that

for the 100~ flow area c se at all speeds

In elaboration ot the second interpretation of Figure

22 attention is directed to the relative magnitudes ot

increased apee1f1c speed tor the two gate openings Assumbull

ing that the increase in specific speed implies a shift ot

the power curve to the right along the turbine speed scale

the power curve would be shifted more tor tbe halt gate

opening than tor the over gate opening

It thia trend could be extrapolated to the other gate

openings the tendency can be seen tor the line ot beat

speed to rotate toward the line of the operating speed as

illustrated in FigtU-e ) The advantage of this has already

been discussed

This particular turbine has a low specific speed tor a

reaction turbine Aa the rated value of apecitic apeed tor

reaction turbines increases the line ot beat speed departs

even more radically from the line of operating bullpeed It a

test similar to this were conducted on a reaction turbine

ot gleater specific speed it is pJobable t hat the rotation

ot the line of beat apeed would become more p~onounced

The scheme used in th1a teat had two obvious dr wbull

backs The first was the decision to leave all the wicket

gamiddottes installed tor all conditions ot the draft tube

These gates predominated in control of the tlow The

inserts added to the draft tube merely acted as auxiliary

55

contrGla

The aecond drawback was the choice or device to place

in the draft tube The reasons foll selection of this type

of device have been previously mentioned It is to be

anticipated that adaptation ot dratt tube flow control

would result 1n a better device for an actual turbine

installation Such apparatus might take the form of a

pneumatic bladder or a h7drau11oally operated variable

venturi section in the draft tube It is conceivable that

the gate as used in this test might be adapted also

Chapter VII

OONCLtJSIOfS

From the results of this test the following eonolubull

e1ona aa to the effect ot a variable draft tube flow area

on the performance or a r action turbine may be drawn

(1) The effect ot a variable draft tube tlow area 1a

generally favorable upon the operat1Gn ot a reaction turbull

bine because or the tendency tor the line or beat speed to

rotate toward the line ot operation This resulte in

better performance of the turbine at partbullloads

(2) he etf1o1ency eh111 tor the turbine beeomaa JDore

tlat at the top leading to a smaller max1JilWD effic1enc7

but e reater etticieney at other pointe of operation with

the insertion ot an auxiliary control ror the rate ot tlov

in the draft tube

(3) The power output of the turbine will increase at

over speed over gate conditione as well a at part gate

conditions with the proper amount or draft tube eonatr1cbull

tion or flow

(4) It is possible to eliminate at least partially

eddy type shock loss by tho introduction ot flow control

in the draft tube

BIBLIOGRAPBl

1 Addison Herbert A treatise on applied h-draul1cs New York Wiley 1954 724 Pbull

2 Allen o M and I A Winter middot Co111parative testa on experimental draft tubes Tranaact1ons ot the American ociety ot Civil Engineers 87t893bull970 1924

3 Barrows a E Water power engineering 3d ed ew York McGraw-Bill 1943 791 Pbull

Bovet G A Modern trenda in hydraulic turbine design4middot in Europe Tranaactions of the American Society ot Mechanical Engineera 75975bull993 1953bull

s Oreager William P and Joel D Justin Hydroelectrichandbook 2d ed New York Wiley 19$0 1151 Pbull

6 Daily Jamea w Hydraulic machinery Int Hunter Rouses Engineering hydraulics Hew York Wiley 19$0 p 8$8bull99

Daughertybull Robert L Bydraulie turbines ew Yorkbull7middot MoGrav-Hlll 1920 281 Pbull

8 Daugherty Robert L Inveat1gat1on of tne performance ot a reaction turbine ~anaactiona or the American Society ot Civil Engineers 7811270bull1304 1915

9 Davie L M Model and prototype testa Int Trend in hydraulle turbine practice symposium lranaactions ot the American Society ot Civil Engineers 1o63S3middot368 1941

lfJ Doland James J Hydro power engineering Hew Yorkbull Ronald 1954 209 Pbull

11 Gandy Theodore s and Elmer c Schacht Direct curshyrent motor and generator troubles operation and repair New York McGraw-Bill 1911 293 Pbull

12 Gibaon Arnold H Hydraulics and ita applications5th ed London Constable 1952 813 Pbull

58

13 Button s P Component loases in Kaplan turbinebull and The prediction of efficiency from model tests Probull coedings of the Institution or Mechanical Engineers168743-762 1954

14 Knapp R T~ Oavit t1on mechanics and its relation to the d sign or hydraulic equip ent Proceedings or tne Institution ot Mechanical Engineers 166150bull16) 1952

15 Langsdorf Alexander s Principles of direct curHnt mach1nee 5th ed New York r~cGrawbullH1ll 1940 746 Pbull

16 Lsrner Chester w Characteristica of modern hydraubull lie turbines Trans e~ions of the ~~erican Society ot Civil Engineers 66306-386 1910

17 Linsley Ray K Jr and Jobulleph B Franzin1 Eleshyments of hydraulic enginebullring New York McGrawshyBill 19$5 $82 Pbull

18 Mead Daniel w Hydraulic machinery llev York McGraw-Hill 1933 396 Pbull

19 ead Daniel w Water power engineering New York McGrawbullRill 191S 843 Pbull

20 Mockmore Charles A Part gate operation at water turbines Corvallis Oregon State College Department ot Civil Engineering 1933 11 numb leaves (Unpubshylshed typescript)

21 Mockmore Oharles A Flow characteristics in elbow dratt tubes Transactions of the Amez-ican Society ot Civil Engineers 103402middot464bull 1938

22 Moody L F Hydraulic machinery In c v Davis Handbook ot applied hydraulics New York McGrawshyHlll 1942 1082 Pbull

2) Ptau At-nold Hydrbullulie turbine handbook ld ed Milwaukee AllisbullOhalmers ManufactUIing Company 1948 70 Pbull

RheingalUI w J Recent developments in Francis turshybines Mechanical Engineering 74189-196 1952

25 Russell George E Hydraulica 5th ed New York Henry Holt 1942 466 Pbull

26 Safford A and E P- Hamilton American mixed tlow turbine and ita setting Tranampactions or the Amerieal Society of Civil Engineers 851237bull1)56 1922

27 bull Spannhake W1lhe1Dh Problems or modern pump and tur b1ne design Transactions of the American Society of Mechanical Engineers 56e22$-248 1934bull

28 Sutherlandraquo R A Better ethod or representing and middot tudying water turbine performance ~ansaetions ot thmiddote American Society of Mechanical Engineers 68t675bull 686 1946

29 Teats ot five models or draft tubes tor turbines Engineering News-Record Pbull 182-184 Aug 2 1923

30 White w M American hydztaulic turbines Mechanical Engineering S2t390bull39S 1930bull

31 White w M lhe hydraucGne rega1ner1 its developmentand appl1eat1ons 1n hydroelectric plants Meohanlobulll Engineering 43t37Sbull380 1921 middot

32 Winter I A Economic principlebull in designbull Int Trend in hydraulic urbin practice bull a ampoeiumTranaaot1ona ot the American Society ot Civil Engineerslo6332bull3S2 1941

33 Wiel1cenua G F Fluid mechan1ca or turbo-machineryNev York McGraw-Hill 1947 613 Pbull

APPENDICES

c

Appendix A

NOATIOB

A Angle between the absolute velocity vector and the tangent to the rwmer Subscripts 1 and 2 refel to entrance and exit ot the runner blade

B Angle between the relative 1elooity vector and the tangent to the rwmer Subscripta 1 and 2 refer to entrance and ezit or the runner blade

Angle between the tangent to the runner blade tip and the tangent to the runnel- Subscripts 1 and 2 reter to entrance and exit of the rt1rmer bladebull

Blade angle-gate opening conetant defined by equation (1)

e 09erall efficiency

g Gravitational acceleration assumed constant at 322 teet per second per second bull

H Turbine head detined by equation ($)

m Exit loss coeft1e1ent

Turbine speed expressed in revolutions per minute

Turbine speed under a constant head of 81 teet

specitic apeed of the turbine under a constant head ot 81 teet

p Power output in horsepower ot the tvbine

Power output of the turbine Ulder a constant head ot Sl teet

Pl- Pressure head at entrance to the tUlb1new

l1 Peripheral velocity ot the runneP Subacr1pta 1 and 2 refer to entrance and exit ot the JUnllampr blade

62

v Relative velocity reaulting trom the combination ot the absolute water velocity V and the runner periphshyeral velocity u Subscripts 1 and 2 refer to entrance and exit ot the runner blade

v] Relative velocity vector necessary to produce a tanbull gential entry into the runner blades

V Absolute water velocity Subscripts l and 2 refer to entrano and exit ot the runner blade

v2 Velocity head Subscripts 1 and 4 reter to the ~8 entrance to the turbine and the tail~ace wate~

w Unit weight ot water assumed constant at 624 pounda per cubic toot

V Weight rate ot flow in pounds per aeooncl

XX Velocity component ot ahook See Figule 2

Z Elevation head Subscripts 1 and 4 reter to entrance to the turbine and the taibace water surfacebull

Appendix B ORIGINAL DATA-Run

lfwnber

0-4-1 0-4-2 0-4-3 o-4-4 o-4-S o-4-6 0-4-7 0-4-8 0-4-9o-4-lo o-4-11 o-4-12 0-4-13

o-6-1 o-6-2 06-3 o-6-4o-6middotS o-6-6 o-6-7 o-6-8 0-6-9 o--6-lo o-6-11

Speed

rmiddot2middotbullmiddot(1)

336 38$ 451 S$9 620 669 6lt)$ 120 787 860 932

102imiddot109 bull

352 355 443middot 543middot 620 654AJs32

911 1001 1111

~essure Head rt (2)

410 410 416 426 431 43-7 439 44-9 452 467 482 soo $1 bull $

350 351 35middot7 )66 37-9 37-9 392 41 bull 3 43middot3 460 489

Elevation Bead

fjj $7 $7 $7 $7 $7 $7 51 57 5-15858 $8 58 56 56 $6565656 51 575As5a

Velocit Head

flj 07 07 07 06 06 06 06 os 05 os0404 03

09 09 oa o8 o8 os 07 07 06 o~o

Total Head rt ($)

47middot4 4A44 o 489 49-4 soo $02 $11 $14 $29 5imiddot45 2 576

41 bull $ 416 421 430 44middot3 44middot3 456 47-7 496 523551

Plow

lbtjec

326 324middot317 311 306 30029middot28 middotmiddot middot 386 275middot260 240 218

359 36~35 bull 349 345middot 339 330 318 300 273 240

Line Potential

vyqjbull 1060 1220 ~-0o 1920 2150 2000 2$60 2000 1940 18)015io11 o

1000 1100 139bull5 1760 1925 16$0 1620 1610 1540 1330 870

Line Current

amlscs 960 900 830 740 730655 70bull 0 530 660 600 5imiddot54 6 )60

982 930 860 780 ~3-545

79-5 74-5 670 560 370

P

Appendix B ORIGINAL DATA (Continued)

Run Number

Speed

Pbulltmiddotbullmiddot )

leasure Head ft(2

Elevation Head tt(J)

Velocity He-dfmiddotj

Total Bead tt($

Flow

lbstsec( )

Line Potential vo~ta( )

Line Current

amjs (sect

0bulllt)-1 0-9-2

3ll6 398

28o ~~1

$6 56

1o 10

346 347

390 365

1ooo 1190

aao 835

0-9-3 0-9-4 o-9-S

472 565 632

292 305 312

$6 s6 56

10 o9 o9

)$8 J7~o 37~7

381376 37o

1)6614oo 141o

820 ass ass o-9-6 0-9-7 0-9-8 o-9-9 0middot9-10

680 120 762 844 920

)24337346 366 390

56 $6 56 57 $7

09 os o8 oa 07

)89401 410 431454

367~ 357348 34o 322

1400 1J6o l36o 1310 1170

843 820 7957So 67~0

0-9-ll 0-912

1001 1100

41 bull 7 45-3

s 7 6~0

06 os 480 $18

299 268

980 65$

560 36~5

1-4-1 1-4-21-4-l1-4shy1-4-5 1-4-6 l-4-7 1 4-8 1-4-9 1-4-10 1middot4-ll 1-4bull12

354middot452 562 62q 674shy102 752 760- 863 932

1022 1100-

)82389 4014oa 416 41--7 423 428 44-2 45-7 486 49-2

51S757 51 5-7 5middot15zs sa $8 58 59

07 07 06 06 06 06 06 os o bull o 04 o J

446 45-)46middot4 471 ti7-9480 q86 491505 $19 548 55-4

)28 320 311 306 300 295 291 286 269 2582iimiddot21 bull

1080 14Lo 1550 153-5 1470 141-0 1385 1310 1310 1230 1120 855

970855 875 91-0 94~0 975 966 995 860 77-S 610 4fo

0 ~

Appendix B ORIGINAL DATA (Contirmed)-Run Speed Pressure Elevation Velocity Total Flow Line Line

Number Head Head Head had Potential Current rtjjmbull t~ bttec vyfs am~a12) ( ) ti fli 8

1-6-l $6 33$ $6 0bull9 400 364 1100 93 0 1-6-2 41 34laquo2 $6 oa 406 JS7middot iios a5s l-6-3 500 3~0 5bull6 os 356 1 1 o aos 41middot~1-6~4 35bull4 5-6 oa 41middot 352 16~0 82 0 5~1-6-5 5 bull 36_2 Sbull6 08 42bull6 349middot 161 ~ 0 86~0 1-6-6 622 366 $6 oe 43bull0 345middot 158 0 88~$ 16-A 649bull 37bull1 56 os 43-S 342middot 1570 895 1~- 386 57 07 46-0 192 ) 125A44 333middot 1-6-9 3) 404 5middot1 07 468 317 1620 675 1610 911 42-4 5-7 o6 48-7 298 168 0 61 0 1-6-11 999 451 56 os Sl ll 276 ~2-0 530 1-612 1115 485 58 04 54middot7 238 90 )3 0

1middot9-l 355 279 56 10 )45 385 1040 870 1-9-2 399 28J $6 10 )49 38$ 1140 86 5 l-9-3 ~ ao 291 56 ~0 35middot1 J8J_ JJ6o 815 1bull9-4 579 303 56 09 )68 375middot J4JO 830 l-9bullS 40- 313 )6 09 31middot8 370- 1460 82~0 1-9bull6 679 2) 56 09 3 bull8 364middot 1670 710 l-9-7 682 319 56 o9 384 ) 62 1460 79 5 l-9-8 724 33middot5 56 o8 399 3$6 bull 1480 76 -5 1-9-9 762 34middot3 $6 0 bull 8 407 )48 14910 13middotS 1-9-10 833middot )60 5middot7 os 42$ 339 144$ 686 1-9-ll 926 39middot1 5-7 07 455 318 1290 600 1-9-12 1000 41middot3 0-6 476 298 1115 510$ ~ 1middot9-13 1105 452 s o4 $14 2$6 710 )10

~

Appendix Bt ORIGDIAL J (Continued)

Run Speed Pressure Elevation Velocity Total Plow Line Line Number Head ltead Head jlamp$d P()ten~ibulll Current

r~~~m ft ft lbs~seo voltattj rgj twimiddot t 1 t2gt lt3 ou t ( rt

2-9-1 384 289 S 6 10 35 5 1400 1170 810 2-9-2 443middot 29$ $6 ltimiddot9 360 379middot 11(0 87$ 2-9-J 536 30bull 3 sc 09 )68 374middot 1)40 84 bull) 2-9-4 571 306 $6 09 3~1 372 120bull 0 955 2-9-5 623 316 S6 09 J l )6S UJSo 77$ 2bull9-6 669 327 S6 09 )92 )61 1240 905 2-9bull7 712 )39 56 os 40-3 351 12(0 86 bull0 2-9-8 ~5$~ J48 56 oa 412 348 1290 81 bull ) 2-9-9 04 )63 56 oa 42-7 339 12ltJO 76$ 2middotmiddot9-10 8$2 376 5middot1 07 440 33~- ~ o 710 2-9-11 955 394 5-1 o6 457 300 1100 506 2middot9-12 1000 421 $7 06 48middoti 295 1020 $18 2-9bull13 110~ 463 56 05 $2 267 620 3~0

oshy0

Appendix Gt CALCULATED DAgA

Turbine Run Generator Generator Turbine Turbine Efficiency Turbine Turbine Specit1c

Number OutputKWlt21

Loa~Jes KWlol

Outut K bull (H)

Input RP 12)

middot Percentlt13gt

Speed r~Jmiddot(

0ltput HP ~1

Speed r-m

( 6) middot

o-4-1 0middot4-2 0-4-3 0-4-4 0-4-5 0-4-6 O-qmiddot7o-4-8o-4-9 0-4bull10 0-4-11 o-4-12

1018 1o9a 1220 1)62J40214oa1J4oo 1357 1320 1164 997 718

046 o59 071 092 096 1071oo 134 104 100 109 107

14261sso 17)01948 2008 20322011 1999 19 09 1708 14-84 11o6

281279 27-7 276 215 273271 268 268 26h 258 24-5

soa 555 62$ 705 7)1145 742 74-6714645 51s 45-1

440 sos 585 720 195 sso sao 9$$ 985

1065 1135middot 1230

318 357 319 416 422 419412 39middot9 378 324 260 191

102 12bull4 148 191 21bull 3 22o 233 249 24924middot9 238 221

0-4middot13 418 104 699 228 306 1300 117 18)

o-6-1 982 045 1376 271 $08 496 376 124 o-6-2 o-6-3 G-6-4o-6-5 0-6-6

1023 1200 13 73 J415 139h

051 0middot66 oaa ()bull 96 088

14-39 1696 1958 2026 1986

276 27middot4 273 278 274

$20 61 8 717 7)0726

q95615745 8)5685

390 ll5middot3 sos soo 490

127 170 218 243 2$$

o-6-7 o-6-8 o-6-9o-6-lo

1288 1199 1032 7-45

o9o 094 09$ 096

1846 1733 1511 1128

274 276 271 260

67S 629559 43middot4

980 1085 1165 1245shy

436 )83316 21bull 7

266 276 270 239

0-6-11 322 1oo 566 2141 2JS 1350 101 177 0 --4

Appendix C CALCULATED DAlA ( Continued)-Run

Number Generator Generator

Out2ut Losaes xw LW- 12gt (lO)

Turbine Out2ut

ltPlJ

Turbine Inat lfP Jig)

Etpound1e1ency

PireentDl

Turbine Sed x-~m( 1

Turbine OutEut RPJl)

Turbine Specific

SeeedrIbullntbull

( 6)

o-9middot1 0-9-2 0-9-3 o-lt)-4 09-$ 0bull9-6 0-9-7 0-9-8 0-9-9 0-9-10 o-9-11 0-9-12

aao 994

111$ 1197 1206 1180 11)21081 982 784 5-49 2)9

0middot45oss o6$ 070 07$ 0-77 (l77 or~ o s06o 8 096

123~ 1402 1$80 1698 17bulllS 168$ 16bull18 ~middot5430 1151 a~J4 9

24middotgt24middot3248 25~25 260 260 259 267 266 26middot1 2S2

sos 577 63-7 671 676 650 621 60036J4

327 178

$) 610AlO 3$

92S 980

102$ 1070 1157middot 1230 1300 137Smiddot

44middot4 soo 523 ssomiddot 540so6 46-5 432 368 274 18~8

J46 176 21-1 255 2802s_A 28 289 288 265 231 168

1-4-1 1-4middot2 1-4-3 1-4-4 1-4-5 1-4-6 1-4-7 1-J-8 1-4~9 1-4-10 1-4-11 1-4-12

10bull48 1231 13-S6 1397 1)821375 1))8 1303 1127 953 683) 51

048 067 o7A07 0 bull79 oa1 oss o bullao osa 0lt)0 096 099

J468 1740 1921 1978 1958 19$1 1911 lSSi162 1)98 1045

603

266 264 262 262 261 2512$7 2$6 24middot7 24-3 233 217

551 660 13middot3155 75-6 7~-97 middot4 72$ 67 51middotJ 44middot9 21middot1

475 605 A4220

875middot 910 970_

1000 1090bull 1166 1243 1330

5816

44middot444middot5 430 427 412 392 329 273 188 l0-7

117 101 204 22$ 2)7245 2562sa 257251 222 179

a-C))

Appendix Ct CALCULATED -DATA ( Ocntinued)

1-6middot1 1023 o$2 14-41 26S 505 41~6 26~

54middot5 13middot3l-6-2 1201 067 1boo 625 47-9 17shy~middot41-6bull3 1296 oA9 1 middot43 26 9 700 so5 20bull 4 l-6-4 l3j5 o 0 19~09 268 71bull3 A5o 514 222 1-6-5 1) 5 o81 19(gt4 271 725 51-5 238 l-66 1398 081 198) 27-0 736 8 S13 252~-middot l-6j 1405 083 199i 211 733 885 $middot06 2$9 l-6 13middot9~ 103 2amp 0 279 71 8 985~ 467 ~-69 1228 1 bull 02 17-SS 270 661 109$ 407 ~3~ l-6bull10 1025 100 lSll 26i 573 1175middot 27~S32middot~l-ampu 153 1-00 llft3 26 444 1270 22 24bull8 1bull6-12 294 100 52a 231 22 3 1360 95 172

1-9bull1 904 048 1275 2J4Z $28 S4$ 459 1$2 1-92 98$ oss 13-92 24middot4 57-0 6JO 49bull1 176 1-9middot3 1110 066 1$76 24middot9 63middot4 I2o 536 21-7 l--9-4 1187 072 1685 251 66$ 5 $$ bull 0 261 1middot9-5 llltJ7 1710 25middot4 67-3 93$ 536 28~20-671middot9-6 1186 o 8 1708 25-7 67) 980 $15 2691-9- 1161 oBo 1660 2$middot3 6$6 990 508 29-1 l~- ll-32 oB) 16sect0 2$8 632 1030 471 291 1-9bull9 109$ oa5 2$7 614 1075 29S~middot 0 4imiddot41-9-10 9~91 oas 262 S$1 1150~ 3 o 292 1-9-11 o9o u57 12JiO 21gt 26-77middot74

-45 26sect ~middot91-912 $69 091 sas 25 middot3 1)0$ 196 2J-8 1-9-1) 220 098 426 2)9 178 1390middot 84 16 6

0 0

Appendx C CALCULATED DATA (Continued)

Turbine Run Generator Generator lurbine Turbine Eft1e1eney Turbine lurbine Spee1f1c

Number Output Losses Outit Input Speed Output SPed middot k_-V KW R _ H_bull_P Percent r Thm HP rpm_ (9) tlo) 11) middot (12 _) (lJI ( ) (1$ (14)

2-9-1 9--46 055 1)62 258 528 580 164 2-9-2 1024 056 248 58 4 665 4 9 191iimiddot48 4~middot0 2-9-3 1132 067 05 2$0 641 795 52q 237 2-9-4 1148 065 1027 2$1 -~8 845 525 252 2-9-5 11 77 oso 16-83 253 6 910~ 522 270 2-9 6 1122 071 1600 251 622 960 47-5 2722-9-A 1092 015 1562 257 608 1010 445 2z12bull9- 1052 079 1514 261 580 1060 41middot7 2 2 2middot9-9 986 o82 ]429 26) 542 1105 372 277 2-9-10 915 086 1340 268 500 1160 334 27-6 2-9-11 638 087 972 254 )81 1270~ 229 250 2-9-12 )28 090 828 259 )19 1295 179 226 2-9-13 192 094 383 2$ 6 150 1370 7 3 152

-3 0

Page 29: The Effect of A Variable Draft Tube Flow Area on the

22

(2 peat (l) with the gate installed in the drat

tube

(3) middot Converting middot all data to a constant head compare the

powere and effioiencies at the same wicket gate setting and

turbin speed tor the two cbullses

If the ddition or the gate indicates an improvement

in power output and efficiency and the powe~ curve shifts

to the right along the turbine apeed scale the advantage

ot draft tube con~ol of the flow will hav been demonshy

strated

Chapter IV

A E9J11pment

ih turbine used in this test is lJ 5 1nch Pelton

reaction turbine with a rated output ot 30 horsepower under

a head of 56 feet at a speed ot 720 reYolutiona per minute

Views of this turbine are hovn in Figures S and 6 The

turbine is installed on a concrete pad located over an open

channel in the Hydraulics Laboratory at Oregon State Colshy

lege The date of manufacture of this turbine was 1915

The water was delivered to the turbine from a sump

reservoir by two pumps operating 1n parallel Each pump 1a

an 8 inch Pelton double suction centrifugal pump witb a

rating of l$00 gallons per minute at a head ot 75 teet with

a speed ot 1175 revolutions per minute Tbe inlet tlange

ot tne turbine is $pprox1mately 18 feet above the center

line of the pump

A direct current generator was coupled to the turbine

to receive tne power d veloped as shown in Figures 4 and 7 The generator is a Spr gue Electrodynamometer rated at SS horsepower with a speed range of 7$0 to l$00 revolut1one

per minute The classification is type LO 26A 2)0 volta

Figure 5 - View of Test Turbine

Figure 6 ~ View of Test Turbine

and 149 amperes lbe generator ti ld was aepar tely

excited using direct current from a motor g n r tor ampt

(l$ p 4~8)

The power output of the generator waa dissipated in

the water rheostat (3 p 488-489) shown in Figures 9 and

10 The galvanized tank contain d water ot variable d pth

on an electrode ot cast iron m aauring 1bull x 1 x 1

In the initial installation of the turbine it was

intended that the power output should be measured with a

Prony brak bull For th purpoa68 or this teat it was decided

that the brake was too instable and the generator was

substituted The platform for raising the generator the

nee asary two teet for alignment was built out of available

material In this case heavy laminated wood blocks reiashy

torced with other timbers were used and bolted through the

concrete deck (11 Pbull 36-$7)

Due to the light concrete deck the lack ot mas in

the platform and the slight misalignment in the flexible

coupling ao e vibration waa encountered It seemed to

ncr aae linearly to a maximum at the speed of bout 750

revolutions per minute Above this speed no vibPation was

noticeable The vibration waa not se~ere and does not

appear to have materially affected the test results

26

B Intrumentat1on ~ eaeur1ng Devices

The pressure head at inlet to the turbine vaa meaave4

bymeane ot two )6 inch waterbullmeroury manometerbull connected

in series as shown in Figure 8

The terminal voltage ot the generator vas meaeured by

a laboratory voltDleter with a range to )00 yolta and callbull

brated to within 15 Yolta

The armature current bull and hence the line current was

measured by a laboratory ammeter with a range to 150 amperea

and callbrated to w1 thin o 7S amperes

Tae rate ot tlow was established by weight and time

meaeurementa The weighing ank has a capacity ot 121 000

poundsJ the weight belng indicated by Toledo direct reading

scales Timing was done with a hand atop watch with clivibull

aion ot 02 second

he ~ater level in the tailrace was dete~1ned by a

hook gauge lhie was read to the nearest 001 toot

The turbine and generator speeds were eaaured by a

hand tachometer The technique of almost cont1nuoua readbull

ings of the speed gave an error ot no more than 5 revolubull

tiona per minute

c Operational Procedure

Atter the water level in the aump was checked to

insure an adequate auppl7 the puapa were primed and

27

Figure 7 - Test Generator and Plattorm

Figure middot8- Instrument Board and Field Rheostat

28

started After venting they were valved for operation 1n

parallel

The motor generator set was started to supply the

field current and the circuit breaker was closed Water

wa added to the water rheostat to the level shown in

Figure 10 ~ field current wae minimized by cutting in

all the f ield resistance in the field rheostat of Figure 8

The l2 inch gate valve shown in Figures 5 and 6 waa

slowly opened and the turbine and generator brought up to

speed The 12 inch gat valve and turbine were vented and

the pumps were checked to insure neither had lost ita prime

lhe water rheostat offers very steady load 1f the

water level is essentially constant and the water temperabull

ture 1a fixed () p 488~89) In order to maintain this

constant temperature it was decided not to circulate the

water in the rheostat but rather to allow the water to

boil thua achieving the desired result A standing wave

was set up on the face ot the electrode by the boiling

action but a atable load was eatablished except at very

low water leYels where th11 agitation led to fluctuationa

in the line current

After putting the turbine and generator on the line

maximum power was dissipated in the rheostat by redueing

the turbine speed to between oSO and Soo revolutions per

minute Salt vas added to the rheoetat wat r to increasemiddot

29

Figure 9 - View of Water Rheostat

Figure 10 - View of Water Rheostat

Separate Field ExcitationFrom Motor-Generator set Compound Water-Mercury

---shy

re Manometer

I Q)

~ 0

~

Book Gauge

Open Channel

I

Slap Reservoir

Figure 11 - Wat~r Flow Diagram and Electrical Layout

31

waiting pe~iod ot perhaps an h~ followed

while the boiling point or the water wbulls reacbe4 During

this ti+ne the manometer was vented end eheoked electrical

measur1ng 1nstlUments were connected end the hook gauge was

adjusted tor elevation

It required about two- houtte tor the generator to reach

its normal operating tempe-ratu~e_ After the water in the

rheostat and generator had reached their operating temperabull

turea it was possible to begin the taking of data

The only vaPiable which was controlled wee the turbineshy

generator speed However the upper l1ut1t of safe line

current was slightly over 100 ampJilPampPes and the eireuit

breaker would open when the current reached lOS ~ere bull

Control was exercised by means ot regulating the water

level and salt 1n the water rheo tat and the res1stsnoe of

the tield rheost t~

The etfeet ot each type ot regulation on the three

variables is shown below

Volta Aaperebull Speed

Inc Dec Inc Dee~ Inc Dec

Wa~e1 Level Inc Dec~ X

X X X X

X

Salt Concentration

Inc Dec X

X X X X

X

field Resistance

Inc Dec

X X

X X

X X

32

Jlot all methods gave the ame amount ot change in a

given variable and a period of experiment and trial led to

the following scheme starting the rune with the lowest

turbine speed the water level was high with a high amount

ot salt and the field resistance was cut completely out

Aa it became necessary to increase the speed tor each

aucceasive run either cutting in t he field resistance

decreasing the salt concentration or lowering the Vater

level would produce the desired result However decreasbull

1ng the salt concentration had to be done Without a net

gain in water which led to a tluahing procedure that was

not particularly good because cold water was introduced

which required time to heat to the boiling point Cutting

1n additional field resistance was a good method but th1a

increased the amperage possibly to the point of opening

the circuit breaker Lowering the water level was aatiashy

factol1 until the level got too low causing the current

fluctuation previously mentioned Actually it turned out

that a combination of lowering the water level and cutting

field resistance in would carry the speed from ita minimum

to 1ts maximum value it the proper choice were made each

time the speed waa to be changed At the conclusion of

each aet of runs at a high speed the water level would be

low and the field resistance high

33

TURBINE

PAD AND DECK

TAILRACE

WATER SURFACamp

CONCRETE

DRAFT TU1B INSERTS

7 5( DRAFr TUBE

FLltJI ARIA

5~ DRAFT TUBE

FLOI ARSA

Figure 12 - Sketch of Draft Tube and Test Inserts

34

Figure 13 - View of Draft Tube Insert

Figure 14 - View of Draft Tube Insert

D c __ ~s_middot hedu_le of

A number was assigned to each run The fi~st number

applies to the draft tube tlow areas

1 bull 100~ flow area or 0~ oonatriction

2 - 7S tlow area or 2$ conatr1ct1on

3 SoC flow area or so~ constriction

The second number refers to the wicket gate openings

9 over gate opening

6 bull intermediate gate opening

4 bull one h lt gate opening

The third number 14entif1ea the location of the particular

1Wl in a set ot rona made at a given dratt tube tlow area

and wicket gate opening

fnua run number 1bull4bull10 would identity this as the

tenth run ot a set made at halt gate with 75 ot the draft

tube t1ow area

Rune w re made tor a g1yen dratt tube condition

Firat tor tull 41-aft tube flow area seta ot rune were

made for the overgate halt gate and intermediate gate

conditione An insert was placed in t he draft tube and

rune based on the same gate conditions were made tor the

7S~ draft tube flow area case The insert was then changed

to allow only $~ draft tube flow area

The inserts are sketched 1n Figure 12 and photographed

ln Flgurea 13 and 14 They oonaisted of circula~ segments

36

or l2 ineh plywood mount 4 on wooden legs 10 inches high

The 1nse7te were placed in position and secured by th use

ot a-clamps on the legs and the outside ot the bottom of

the draft tube The obvious disadvantage to this method

waa the neoeasity tor draining the water from the tailrace

tor a change ot 1naert The advantage vas of course the

simplicity ot design and construction

Chapter V

DATA-A Original Data

The normal data-taking crew consisted or two men

Assuming adjustments having been made to secure a certain

turbine speed (aee section on Operational Procedure) one

man would take semi-continuous speed readings with the hand

tachometer until a state or rotational equilibrium was

reached This could be only a period or two minutes up to

ten or tifteen minutes As soon as steady speed was

assured the data taking would begin The second man went

to the weighing tank Where a minimum ot three weighingamp

were made The requirement was to get three consecutive

readings such that the ditterence between tbe smallest and

largest time did not exceed 04 seconds The time to

collect a given weight ot water was then assumed to be the

arithmetic average of the three times He then went to the

hook gauge determined the hook elevation and then

recorded the data on the data sheets The first man meanshy

while had taken readings of the line voltage line current

and manometers and checked the turbine speed by multiple

readings During the length of the run all values were

38

checked to determine mean values for recording

The minimum length of one run was about five minutes

If one or more measure ants tended to drift during the run

all values wer discarded and a new run began as soon aa

qu111br1um was stabl1shedo

B -0-al_e_u_l_a_t--d Data

The h d on the tu~bine 1 defined by

($)

The maxtmwm velocity V4 was equal to about o8 tampet per

secon4 which makes it a negligible quantity when converted

into velocity head

An engineerbulla level was used to deterine the d1ffePshy

ence 1n elevation between the compound water-mercury manoshy

meter and the hook gauge Using this value the equation

for turbine bead becomes

where z4 is the hook gauge reading

The rate of flow 1 cent

w weight or water collected average time to collect

The inlet velocity v1 vas calculated by dividing the

weight rate or flow by the specific weight of water and the

)9

area ot ~e inlet pipe This was equivalent to dividing

the weight rate of flow by 490 Then the power input to the turbine is equal to

WHpin rri

10 (6)

Also

(P ~ut) Turbine

(P out) + Generator

(P lost) Generator

The power output of the generator is simplJ the

produot ot the terminal voltage and the armature (line)

curPent The power lost in the generator can be subdivided

into copper losses and stray power losses lo evaluate

these cunes based on losses of an identical generator

11leampsured by the Department ot Mechanical Engineering were

used The loss curves are reppoduced in part in Figures

15 and 16

Determination ot generator losses proceeds as tollowau

(1) From Figure 15 detem1ne the vo1tage drop in the

armature circuit using the temperatures of 1220 F and the

meaaured current

(2) The induced voltage is t~e sum of the terminal

voltage and the voltage drop 1n the armature circuit

() Entering the induced voltage and the turbine speed

into Figure 16 the stray power loss can be determined

(4) The copper lose can be evaluated from Figure 1$

using the measured current and the temperatlll-e of 1220 P

40

25 ~------~--------~--------~------~

U) -U) - 20

f-4 ~

-~ -gt 0

0

VOLTAGE DROP

~ - i -

- bullbullbull bull - -middot-middot -+ ~- + -t--+ ~ - ~ middotbull ~-~ middott- -+----- _ -4 middotmiddot- --~-+-t---r~~ ~--+t-t- - ---t-c-++~-ulf--

0 50 75 100

Figure 15 - Curves of Generator Voltage Drop and Copper Loss

41

1200

1000

800

600

800

0

0

~-

middot--~ 1shy --1 + bull l

100

I -

150 200

IIDOOED VOLTAGB (VOLTS)

Figure 16 - Curves of Generator Stray Power Loss

_ j

-bullshy -L---- shy middot -shy

250

- r

42

(5) The generator los os equal the sum of the eopp r

loss and stray power loss

~e efficiency or the turbine is taken as

etticiency u e =P out (8)Pin

~ample pound Determ1n1gg turbine Power Output

The following data are taken trom that ot Run 1-9-1

Line voltage 1040 volts Line current 870 amperesSpeed 355 revolutions per minute

The induced voltage 1a determined as follows

Line voltage 1040

Voltage drop 90 using Figure 15 with line current of 870 amperes and temperature ot 122 degrees)

Induced Toltage 1130 volta

The power output of the turbine is determined as follows

Generator output 90$0 (line voltage z line current)

Oopper loss 7 (using Figure 15 with line current of 870 amperes and temperatUe or 122 degrees)

Stray power lose 470 (using Figure 16 with speed ot 355 revolutions per miDUte and induced voltage or 1130 volts)

Turbine power output 9527 vatta

or turbine power output 1s 12z2 horsepower

43

The conversion of the calculated data to a constant

head is based on the conventional assumption of constant

efficiency regardless of turbine head For a constant head

ot 81 teet a purely arbitrary figure the tollowing relashy

tionships are ass1lJiled to be true

I ____L (9) (i)l72

(10)

For these two values the specific a peed may be combull

putedt

N t Jt VPt (11)8 243

Chapter VI

~RESULTS

A -Pr_e_ae_n_t_a_t_t_o~n g Reaultbull

Graphical presentation ot the results ot this te1t

are given as follows

Figure 17 -Turbine characteristics with 100~ dratt

tuba 1low area

Figure 18 - Turbine characteristics with 7S dratt

tube tlow area

Figure 19 bull Comparison ot power and etticiency at

over gate conditions between 100 and

75~ draft tube flow area

Figure 20 bull COZQparison of power and ettic1ency at

halt gate conditions between 100~ and

7S~ draft tube flow area

Figure 21 bull Comparison of power and etticiency at

over gate condition between 100~ and

So dratt tube tlow area

Figure 22 - Comparison in variation ot apec1t1c

speed between 100 and 75~ dratt tube

tlow area

50

45

20

-bull - 1--shy40

bull J-~ 30

~ ex

~ 20

~~ ~ -)q

I

~ - _

- -

10~ OF DRAFT TUBE FL(Jif AREA

CONSTANT HEAD OF 8l FEST10

POIER OUTPUT EFFICIENCY SPECIFIC SPEED

0 ~--------------_--------~------~------~ 400 600 800 1000 1200 1400

TURBINE SPEED (RPM)

Figure 17 - Turbine Char~cteristics with 100 Draft Tube Flow Area

50

46

-bulllle

~ 7 ~ OF DRAFt TUBE FLOW AREA

0 -~~-rl C05STAMT BEAD OF 81 mET 1J~

POIER OOTPUT ---+- ---o ~_H EFFICIDCY ~ I shy

bull ql SPECIFIC SPEKD - ~ -

bull ~ J 10 L rmiddotr- r- -

bullz- I

~~ 30 ~~--~----~~-

20 ~ ~ middot-shy

26

~~ 25

~0 ~r-----i (

Tbull -bullshy

400 600 800 1000 1200 1400

TURBINE SPEED (R PK )

Figure 18 -Turbine Characteristics with 75 Draft Tube Flow Area

47

EFFICIENCY 60

1-----shy

-~ 50~--~--~~-~middot middot middot middot r~-~----~~~~---4~-r~-~~gtt

II

POWER~ J ~ bull bull

u I

sH

40~------+-------+---- -~~--~~-~~~~

~----~rl 1 bull

I

I

0~--------------~------_------~--------

~ -OVER GATE CONDITION

COIJSTANT HEAD OF 81 FEET

0 o 10~ DRAFt TUBE

_-- _ 7~ DRAFT TUBamp FLON AREA II

10_~-----+--------r-------r----~~

400 600 800 1000 1200 1400

TURBINE SPEED (RPM)

Figure 19 middot - Comparison between 75 and 100 Draft Tube Flow Areas of Power and Efficiency at Over Gate Conshydition

48

t

bull --4 r ~- ~ middot~

70 1-----------+-~~~~~+middot ~ ~~ middot middot -~~--~~--------~~----~-+1

-~-

Atbull bull

lla-

60

amp0

40

20

10

oampOO

t _ - - ~-+- - -~-

l2 GATB COJIDITIOJJ

COJISTABT HJW) OF 81 JBET

o 0 lOQ( DRAFl TUB8 FLOI AREA

e-- - e 75 DRAFT TUBE FLOW AREA

800 1000

- r-

~

TURBIbull SPBIID (RPII)

Figure 20 - Comparison between 75 and 100 Draft Tube Flow Areas of Power and Efficiency at Half Gate Conshydition

49

60

50

-40

bull 30

IIQbull

20

10

0

400

- t - ~

EFFICIENCY

_J bull - bull bull

~ r r middot t -+ shy L -t -

OVER GAD COliDITIOI

CONSTABT BEAD OF 8l FBB

o o 10~ DRAFt TUBE FLOI ADA middot--- 5~ DRAF TUBE FLQPi AREA

600 800 1000 1200

Figure 21 -Comparison between 50~ and 100~ Draft Tube Flow Areas of Power and Efficiency at Ove~ Gate Conshydition

50

25

20

15

10

0

Figure 22

~- T -4 -t- -l --~-

t-~ I

middot --~- t ~---- _ __ _ + --

----~- --r-- --

~-=J-~-=-~ -==~ _ ~- -- ---f---1 - shy

CONSTANT HEAD OF 81 FEBT

o--o 1~ DRAFT TUBE FLltll AREA

75C DRMT TUBK FLCIJ AREAmiddot--middot-middot 600 800 1000

TURBINE SPEED (RPK)

Comparison of Specific Speeds for 75 and 100 Draft Tube Flow Areas

51

B Discussion 2 Result

Consideration of Figures 17 and 18 indicates the

overall eftioi ncy pattern or hill is significantly or

rounded for the 7$~ flow area than for the 100~ flow area

bia implies a greateP efficiency is possible at speeds

leas than or greater than design speed with an insert in

the draft tube However the muilDum efficiency is lemiddotas

Direct comparison at over gate conditions is made in

Figure 19 ~e same general trend is noted tor both the

etticiency and power curves for the 7$~ flow area case

The eurves show higher values at overspeed than do the

correaponding cWvea for the 100 flow area case It ia

not clear whether the curves have been shifted by the dratt

tube constriction or whether the curves simply bulge past

the normal curves at both overspeed and underspeed condishy

tions The power curves apparently peak near the aeme

point bullalthough maximum power is still obtained with the

normal draft tube area

For the comparison at halt gate operation shown in

Figure 20 a general improvement has apparently been made

by restriction of the draft tube flow area At every speed

the etticienoy and the power is greater for the restricted

tlow case The two ett1o1ency curves and two power curvea

are practically parallel throughout the speed range ot

teat

As the flou aroa i e decreased still farther a s1gn1

ticant change appears Reterr1ng to Figllle 211 tor the $0

flow area curves it a obvious that exit losses have

become excessive at the overgate condition because the

efficiency and power are everywhere leas than tor the case

of normal draf t tube area

Earlier it was pointed out t hat 1t the r esult s 1nd1bull

eated an increase in both power and ef tieiency- t hen it

could be assumed tha t the additional los s i ntroduced with

the draft tube insert is less than the diminished losses

due to leas shock losa and water passage losses For the

places where both the efficiency and power have been

increased we can assume that the insert has improved turshy

bine performance

For the places where the power haa been decreased

nothing can be said as to the elimination of ampbock loss

because the new lose present with the drat tube insert has

overshadowed any gains in eftecti Ve head upatJ-eam of the

insert

Near the peak of the efficiency hill howeve~ it may

be pointed out t hat shock loaa ie a minimum with a normal

draft tube and the insert merely adds an additional loss

with the resultant decrease in maximum efficiency tor the

7$~ flow area case

Perhaps the most s1gn1ticant set of eurves is shown aa

53

Figure 22 In this graph values of specific speed tor the

75 and 100~ flow area cases for both over gate and one

halt gate openings are plotted against turbine speed At

every speed and both gate openings the value ot specific

speed for th 75~ flow area case is greater than that for

the 100 t1ow area ease

Since the head is a constant for both situations this

may be interpreted in either of two ways trom equation

(11)

(1) For the same turbine apeed restriction of the

draft tube t1ow area resulted in greater turbine power

(2) For the same power amputput the turbine with 75~

draft tube flow area operated at a greater speed than did

the one with 100 flow area

Since the required diameter of a turbine varies

inversely with the speed the second interpretation could

be stated such that a smaller turbine could be used to

develop the same power output

Whether viewed trom the aspect of increased power

greater speed or reduced size the performance of the turshy

bine with reduced draft tube flow area is superior to that

with the nolmal flow are in the draft tube

The curve of specmiddotific speed versus turbine speed for

the so draft tube flow area case at over gate cond1t1ona

was not included in Figure 22 This curve lies below that

for the 100~ flow area c se at all speeds

In elaboration ot the second interpretation of Figure

22 attention is directed to the relative magnitudes ot

increased apee1f1c speed tor the two gate openings Assumbull

ing that the increase in specific speed implies a shift ot

the power curve to the right along the turbine speed scale

the power curve would be shifted more tor tbe halt gate

opening than tor the over gate opening

It thia trend could be extrapolated to the other gate

openings the tendency can be seen tor the line ot beat

speed to rotate toward the line of the operating speed as

illustrated in FigtU-e ) The advantage of this has already

been discussed

This particular turbine has a low specific speed tor a

reaction turbine Aa the rated value of apecitic apeed tor

reaction turbines increases the line ot beat speed departs

even more radically from the line of operating bullpeed It a

test similar to this were conducted on a reaction turbine

ot gleater specific speed it is pJobable t hat the rotation

ot the line of beat apeed would become more p~onounced

The scheme used in th1a teat had two obvious dr wbull

backs The first was the decision to leave all the wicket

gamiddottes installed tor all conditions ot the draft tube

These gates predominated in control of the tlow The

inserts added to the draft tube merely acted as auxiliary

55

contrGla

The aecond drawback was the choice or device to place

in the draft tube The reasons foll selection of this type

of device have been previously mentioned It is to be

anticipated that adaptation ot dratt tube flow control

would result 1n a better device for an actual turbine

installation Such apparatus might take the form of a

pneumatic bladder or a h7drau11oally operated variable

venturi section in the draft tube It is conceivable that

the gate as used in this test might be adapted also

Chapter VII

OONCLtJSIOfS

From the results of this test the following eonolubull

e1ona aa to the effect ot a variable draft tube flow area

on the performance or a r action turbine may be drawn

(1) The effect ot a variable draft tube tlow area 1a

generally favorable upon the operat1Gn ot a reaction turbull

bine because or the tendency tor the line or beat speed to

rotate toward the line ot operation This resulte in

better performance of the turbine at partbullloads

(2) he etf1o1ency eh111 tor the turbine beeomaa JDore

tlat at the top leading to a smaller max1JilWD effic1enc7

but e reater etticieney at other pointe of operation with

the insertion ot an auxiliary control ror the rate ot tlov

in the draft tube

(3) The power output of the turbine will increase at

over speed over gate conditione as well a at part gate

conditions with the proper amount or draft tube eonatr1cbull

tion or flow

(4) It is possible to eliminate at least partially

eddy type shock loss by tho introduction ot flow control

in the draft tube

BIBLIOGRAPBl

1 Addison Herbert A treatise on applied h-draul1cs New York Wiley 1954 724 Pbull

2 Allen o M and I A Winter middot Co111parative testa on experimental draft tubes Tranaact1ons ot the American ociety ot Civil Engineers 87t893bull970 1924

3 Barrows a E Water power engineering 3d ed ew York McGraw-Bill 1943 791 Pbull

Bovet G A Modern trenda in hydraulic turbine design4middot in Europe Tranaactions of the American Society ot Mechanical Engineera 75975bull993 1953bull

s Oreager William P and Joel D Justin Hydroelectrichandbook 2d ed New York Wiley 19$0 1151 Pbull

6 Daily Jamea w Hydraulic machinery Int Hunter Rouses Engineering hydraulics Hew York Wiley 19$0 p 8$8bull99

Daughertybull Robert L Bydraulie turbines ew Yorkbull7middot MoGrav-Hlll 1920 281 Pbull

8 Daugherty Robert L Inveat1gat1on of tne performance ot a reaction turbine ~anaactiona or the American Society ot Civil Engineers 7811270bull1304 1915

9 Davie L M Model and prototype testa Int Trend in hydraulle turbine practice symposium lranaactions ot the American Society ot Civil Engineers 1o63S3middot368 1941

lfJ Doland James J Hydro power engineering Hew Yorkbull Ronald 1954 209 Pbull

11 Gandy Theodore s and Elmer c Schacht Direct curshyrent motor and generator troubles operation and repair New York McGraw-Bill 1911 293 Pbull

12 Gibaon Arnold H Hydraulics and ita applications5th ed London Constable 1952 813 Pbull

58

13 Button s P Component loases in Kaplan turbinebull and The prediction of efficiency from model tests Probull coedings of the Institution or Mechanical Engineers168743-762 1954

14 Knapp R T~ Oavit t1on mechanics and its relation to the d sign or hydraulic equip ent Proceedings or tne Institution ot Mechanical Engineers 166150bull16) 1952

15 Langsdorf Alexander s Principles of direct curHnt mach1nee 5th ed New York r~cGrawbullH1ll 1940 746 Pbull

16 Lsrner Chester w Characteristica of modern hydraubull lie turbines Trans e~ions of the ~~erican Society ot Civil Engineers 66306-386 1910

17 Linsley Ray K Jr and Jobulleph B Franzin1 Eleshyments of hydraulic enginebullring New York McGrawshyBill 19$5 $82 Pbull

18 Mead Daniel w Hydraulic machinery llev York McGraw-Hill 1933 396 Pbull

19 ead Daniel w Water power engineering New York McGrawbullRill 191S 843 Pbull

20 Mockmore Charles A Part gate operation at water turbines Corvallis Oregon State College Department ot Civil Engineering 1933 11 numb leaves (Unpubshylshed typescript)

21 Mockmore Oharles A Flow characteristics in elbow dratt tubes Transactions of the Amez-ican Society ot Civil Engineers 103402middot464bull 1938

22 Moody L F Hydraulic machinery In c v Davis Handbook ot applied hydraulics New York McGrawshyHlll 1942 1082 Pbull

2) Ptau At-nold Hydrbullulie turbine handbook ld ed Milwaukee AllisbullOhalmers ManufactUIing Company 1948 70 Pbull

RheingalUI w J Recent developments in Francis turshybines Mechanical Engineering 74189-196 1952

25 Russell George E Hydraulica 5th ed New York Henry Holt 1942 466 Pbull

26 Safford A and E P- Hamilton American mixed tlow turbine and ita setting Tranampactions or the Amerieal Society of Civil Engineers 851237bull1)56 1922

27 bull Spannhake W1lhe1Dh Problems or modern pump and tur b1ne design Transactions of the American Society of Mechanical Engineers 56e22$-248 1934bull

28 Sutherlandraquo R A Better ethod or representing and middot tudying water turbine performance ~ansaetions ot thmiddote American Society of Mechanical Engineers 68t675bull 686 1946

29 Teats ot five models or draft tubes tor turbines Engineering News-Record Pbull 182-184 Aug 2 1923

30 White w M American hydztaulic turbines Mechanical Engineering S2t390bull39S 1930bull

31 White w M lhe hydraucGne rega1ner1 its developmentand appl1eat1ons 1n hydroelectric plants Meohanlobulll Engineering 43t37Sbull380 1921 middot

32 Winter I A Economic principlebull in designbull Int Trend in hydraulic urbin practice bull a ampoeiumTranaaot1ona ot the American Society ot Civil Engineerslo6332bull3S2 1941

33 Wiel1cenua G F Fluid mechan1ca or turbo-machineryNev York McGraw-Hill 1947 613 Pbull

APPENDICES

c

Appendix A

NOATIOB

A Angle between the absolute velocity vector and the tangent to the rwmer Subscripts 1 and 2 refel to entrance and exit ot the runner blade

B Angle between the relative 1elooity vector and the tangent to the rwmer Subscripta 1 and 2 refer to entrance and ezit or the runner blade

Angle between the tangent to the runner blade tip and the tangent to the runnel- Subscripts 1 and 2 reter to entrance and exit of the rt1rmer bladebull

Blade angle-gate opening conetant defined by equation (1)

e 09erall efficiency

g Gravitational acceleration assumed constant at 322 teet per second per second bull

H Turbine head detined by equation ($)

m Exit loss coeft1e1ent

Turbine speed expressed in revolutions per minute

Turbine speed under a constant head of 81 teet

specitic apeed of the turbine under a constant head ot 81 teet

p Power output in horsepower ot the tvbine

Power output of the turbine Ulder a constant head ot Sl teet

Pl- Pressure head at entrance to the tUlb1new

l1 Peripheral velocity ot the runneP Subacr1pta 1 and 2 refer to entrance and exit ot the JUnllampr blade

62

v Relative velocity reaulting trom the combination ot the absolute water velocity V and the runner periphshyeral velocity u Subscripts 1 and 2 refer to entrance and exit ot the runner blade

v] Relative velocity vector necessary to produce a tanbull gential entry into the runner blades

V Absolute water velocity Subscripts l and 2 refer to entrano and exit ot the runner blade

v2 Velocity head Subscripts 1 and 4 reter to the ~8 entrance to the turbine and the tail~ace wate~

w Unit weight ot water assumed constant at 624 pounda per cubic toot

V Weight rate ot flow in pounds per aeooncl

XX Velocity component ot ahook See Figule 2

Z Elevation head Subscripts 1 and 4 reter to entrance to the turbine and the taibace water surfacebull

Appendix B ORIGINAL DATA-Run

lfwnber

0-4-1 0-4-2 0-4-3 o-4-4 o-4-S o-4-6 0-4-7 0-4-8 0-4-9o-4-lo o-4-11 o-4-12 0-4-13

o-6-1 o-6-2 06-3 o-6-4o-6middotS o-6-6 o-6-7 o-6-8 0-6-9 o--6-lo o-6-11

Speed

rmiddot2middotbullmiddot(1)

336 38$ 451 S$9 620 669 6lt)$ 120 787 860 932

102imiddot109 bull

352 355 443middot 543middot 620 654AJs32

911 1001 1111

~essure Head rt (2)

410 410 416 426 431 43-7 439 44-9 452 467 482 soo $1 bull $

350 351 35middot7 )66 37-9 37-9 392 41 bull 3 43middot3 460 489

Elevation Bead

fjj $7 $7 $7 $7 $7 $7 51 57 5-15858 $8 58 56 56 $6565656 51 575As5a

Velocit Head

flj 07 07 07 06 06 06 06 os 05 os0404 03

09 09 oa o8 o8 os 07 07 06 o~o

Total Head rt ($)

47middot4 4A44 o 489 49-4 soo $02 $11 $14 $29 5imiddot45 2 576

41 bull $ 416 421 430 44middot3 44middot3 456 47-7 496 523551

Plow

lbtjec

326 324middot317 311 306 30029middot28 middotmiddot middot 386 275middot260 240 218

359 36~35 bull 349 345middot 339 330 318 300 273 240

Line Potential

vyqjbull 1060 1220 ~-0o 1920 2150 2000 2$60 2000 1940 18)015io11 o

1000 1100 139bull5 1760 1925 16$0 1620 1610 1540 1330 870

Line Current

amlscs 960 900 830 740 730655 70bull 0 530 660 600 5imiddot54 6 )60

982 930 860 780 ~3-545

79-5 74-5 670 560 370

P

Appendix B ORIGINAL DATA (Continued)

Run Number

Speed

Pbulltmiddotbullmiddot )

leasure Head ft(2

Elevation Head tt(J)

Velocity He-dfmiddotj

Total Bead tt($

Flow

lbstsec( )

Line Potential vo~ta( )

Line Current

amjs (sect

0bulllt)-1 0-9-2

3ll6 398

28o ~~1

$6 56

1o 10

346 347

390 365

1ooo 1190

aao 835

0-9-3 0-9-4 o-9-S

472 565 632

292 305 312

$6 s6 56

10 o9 o9

)$8 J7~o 37~7

381376 37o

1)6614oo 141o

820 ass ass o-9-6 0-9-7 0-9-8 o-9-9 0middot9-10

680 120 762 844 920

)24337346 366 390

56 $6 56 57 $7

09 os o8 oa 07

)89401 410 431454

367~ 357348 34o 322

1400 1J6o l36o 1310 1170

843 820 7957So 67~0

0-9-ll 0-912

1001 1100

41 bull 7 45-3

s 7 6~0

06 os 480 $18

299 268

980 65$

560 36~5

1-4-1 1-4-21-4-l1-4shy1-4-5 1-4-6 l-4-7 1 4-8 1-4-9 1-4-10 1middot4-ll 1-4bull12

354middot452 562 62q 674shy102 752 760- 863 932

1022 1100-

)82389 4014oa 416 41--7 423 428 44-2 45-7 486 49-2

51S757 51 5-7 5middot15zs sa $8 58 59

07 07 06 06 06 06 06 os o bull o 04 o J

446 45-)46middot4 471 ti7-9480 q86 491505 $19 548 55-4

)28 320 311 306 300 295 291 286 269 2582iimiddot21 bull

1080 14Lo 1550 153-5 1470 141-0 1385 1310 1310 1230 1120 855

970855 875 91-0 94~0 975 966 995 860 77-S 610 4fo

0 ~

Appendix B ORIGINAL DATA (Contirmed)-Run Speed Pressure Elevation Velocity Total Flow Line Line

Number Head Head Head had Potential Current rtjjmbull t~ bttec vyfs am~a12) ( ) ti fli 8

1-6-l $6 33$ $6 0bull9 400 364 1100 93 0 1-6-2 41 34laquo2 $6 oa 406 JS7middot iios a5s l-6-3 500 3~0 5bull6 os 356 1 1 o aos 41middot~1-6~4 35bull4 5-6 oa 41middot 352 16~0 82 0 5~1-6-5 5 bull 36_2 Sbull6 08 42bull6 349middot 161 ~ 0 86~0 1-6-6 622 366 $6 oe 43bull0 345middot 158 0 88~$ 16-A 649bull 37bull1 56 os 43-S 342middot 1570 895 1~- 386 57 07 46-0 192 ) 125A44 333middot 1-6-9 3) 404 5middot1 07 468 317 1620 675 1610 911 42-4 5-7 o6 48-7 298 168 0 61 0 1-6-11 999 451 56 os Sl ll 276 ~2-0 530 1-612 1115 485 58 04 54middot7 238 90 )3 0

1middot9-l 355 279 56 10 )45 385 1040 870 1-9-2 399 28J $6 10 )49 38$ 1140 86 5 l-9-3 ~ ao 291 56 ~0 35middot1 J8J_ JJ6o 815 1bull9-4 579 303 56 09 )68 375middot J4JO 830 l-9bullS 40- 313 )6 09 31middot8 370- 1460 82~0 1-9bull6 679 2) 56 09 3 bull8 364middot 1670 710 l-9-7 682 319 56 o9 384 ) 62 1460 79 5 l-9-8 724 33middot5 56 o8 399 3$6 bull 1480 76 -5 1-9-9 762 34middot3 $6 0 bull 8 407 )48 14910 13middotS 1-9-10 833middot )60 5middot7 os 42$ 339 144$ 686 1-9-ll 926 39middot1 5-7 07 455 318 1290 600 1-9-12 1000 41middot3 0-6 476 298 1115 510$ ~ 1middot9-13 1105 452 s o4 $14 2$6 710 )10

~

Appendix Bt ORIGDIAL J (Continued)

Run Speed Pressure Elevation Velocity Total Plow Line Line Number Head ltead Head jlamp$d P()ten~ibulll Current

r~~~m ft ft lbs~seo voltattj rgj twimiddot t 1 t2gt lt3 ou t ( rt

2-9-1 384 289 S 6 10 35 5 1400 1170 810 2-9-2 443middot 29$ $6 ltimiddot9 360 379middot 11(0 87$ 2-9-J 536 30bull 3 sc 09 )68 374middot 1)40 84 bull) 2-9-4 571 306 $6 09 3~1 372 120bull 0 955 2-9-5 623 316 S6 09 J l )6S UJSo 77$ 2bull9-6 669 327 S6 09 )92 )61 1240 905 2-9bull7 712 )39 56 os 40-3 351 12(0 86 bull0 2-9-8 ~5$~ J48 56 oa 412 348 1290 81 bull ) 2-9-9 04 )63 56 oa 42-7 339 12ltJO 76$ 2middotmiddot9-10 8$2 376 5middot1 07 440 33~- ~ o 710 2-9-11 955 394 5-1 o6 457 300 1100 506 2middot9-12 1000 421 $7 06 48middoti 295 1020 $18 2-9bull13 110~ 463 56 05 $2 267 620 3~0

oshy0

Appendix Gt CALCULATED DAgA

Turbine Run Generator Generator Turbine Turbine Efficiency Turbine Turbine Specit1c

Number OutputKWlt21

Loa~Jes KWlol

Outut K bull (H)

Input RP 12)

middot Percentlt13gt

Speed r~Jmiddot(

0ltput HP ~1

Speed r-m

( 6) middot

o-4-1 0middot4-2 0-4-3 0-4-4 0-4-5 0-4-6 O-qmiddot7o-4-8o-4-9 0-4bull10 0-4-11 o-4-12

1018 1o9a 1220 1)62J40214oa1J4oo 1357 1320 1164 997 718

046 o59 071 092 096 1071oo 134 104 100 109 107

14261sso 17)01948 2008 20322011 1999 19 09 1708 14-84 11o6

281279 27-7 276 215 273271 268 268 26h 258 24-5

soa 555 62$ 705 7)1145 742 74-6714645 51s 45-1

440 sos 585 720 195 sso sao 9$$ 985

1065 1135middot 1230

318 357 319 416 422 419412 39middot9 378 324 260 191

102 12bull4 148 191 21bull 3 22o 233 249 24924middot9 238 221

0-4middot13 418 104 699 228 306 1300 117 18)

o-6-1 982 045 1376 271 $08 496 376 124 o-6-2 o-6-3 G-6-4o-6-5 0-6-6

1023 1200 13 73 J415 139h

051 0middot66 oaa ()bull 96 088

14-39 1696 1958 2026 1986

276 27middot4 273 278 274

$20 61 8 717 7)0726

q95615745 8)5685

390 ll5middot3 sos soo 490

127 170 218 243 2$$

o-6-7 o-6-8 o-6-9o-6-lo

1288 1199 1032 7-45

o9o 094 09$ 096

1846 1733 1511 1128

274 276 271 260

67S 629559 43middot4

980 1085 1165 1245shy

436 )83316 21bull 7

266 276 270 239

0-6-11 322 1oo 566 2141 2JS 1350 101 177 0 --4

Appendix C CALCULATED DAlA ( Continued)-Run

Number Generator Generator

Out2ut Losaes xw LW- 12gt (lO)

Turbine Out2ut

ltPlJ

Turbine Inat lfP Jig)

Etpound1e1ency

PireentDl

Turbine Sed x-~m( 1

Turbine OutEut RPJl)

Turbine Specific

SeeedrIbullntbull

( 6)

o-9middot1 0-9-2 0-9-3 o-lt)-4 09-$ 0bull9-6 0-9-7 0-9-8 0-9-9 0-9-10 o-9-11 0-9-12

aao 994

111$ 1197 1206 1180 11)21081 982 784 5-49 2)9

0middot45oss o6$ 070 07$ 0-77 (l77 or~ o s06o 8 096

123~ 1402 1$80 1698 17bulllS 168$ 16bull18 ~middot5430 1151 a~J4 9

24middotgt24middot3248 25~25 260 260 259 267 266 26middot1 2S2

sos 577 63-7 671 676 650 621 60036J4

327 178

$) 610AlO 3$

92S 980

102$ 1070 1157middot 1230 1300 137Smiddot

44middot4 soo 523 ssomiddot 540so6 46-5 432 368 274 18~8

J46 176 21-1 255 2802s_A 28 289 288 265 231 168

1-4-1 1-4middot2 1-4-3 1-4-4 1-4-5 1-4-6 1-4-7 1-J-8 1-4~9 1-4-10 1-4-11 1-4-12

10bull48 1231 13-S6 1397 1)821375 1))8 1303 1127 953 683) 51

048 067 o7A07 0 bull79 oa1 oss o bullao osa 0lt)0 096 099

J468 1740 1921 1978 1958 19$1 1911 lSSi162 1)98 1045

603

266 264 262 262 261 2512$7 2$6 24middot7 24-3 233 217

551 660 13middot3155 75-6 7~-97 middot4 72$ 67 51middotJ 44middot9 21middot1

475 605 A4220

875middot 910 970_

1000 1090bull 1166 1243 1330

5816

44middot444middot5 430 427 412 392 329 273 188 l0-7

117 101 204 22$ 2)7245 2562sa 257251 222 179

a-C))

Appendix Ct CALCULATED -DATA ( Ocntinued)

1-6middot1 1023 o$2 14-41 26S 505 41~6 26~

54middot5 13middot3l-6-2 1201 067 1boo 625 47-9 17shy~middot41-6bull3 1296 oA9 1 middot43 26 9 700 so5 20bull 4 l-6-4 l3j5 o 0 19~09 268 71bull3 A5o 514 222 1-6-5 1) 5 o81 19(gt4 271 725 51-5 238 l-66 1398 081 198) 27-0 736 8 S13 252~-middot l-6j 1405 083 199i 211 733 885 $middot06 2$9 l-6 13middot9~ 103 2amp 0 279 71 8 985~ 467 ~-69 1228 1 bull 02 17-SS 270 661 109$ 407 ~3~ l-6bull10 1025 100 lSll 26i 573 1175middot 27~S32middot~l-ampu 153 1-00 llft3 26 444 1270 22 24bull8 1bull6-12 294 100 52a 231 22 3 1360 95 172

1-9bull1 904 048 1275 2J4Z $28 S4$ 459 1$2 1-92 98$ oss 13-92 24middot4 57-0 6JO 49bull1 176 1-9middot3 1110 066 1$76 24middot9 63middot4 I2o 536 21-7 l--9-4 1187 072 1685 251 66$ 5 $$ bull 0 261 1middot9-5 llltJ7 1710 25middot4 67-3 93$ 536 28~20-671middot9-6 1186 o 8 1708 25-7 67) 980 $15 2691-9- 1161 oBo 1660 2$middot3 6$6 990 508 29-1 l~- ll-32 oB) 16sect0 2$8 632 1030 471 291 1-9bull9 109$ oa5 2$7 614 1075 29S~middot 0 4imiddot41-9-10 9~91 oas 262 S$1 1150~ 3 o 292 1-9-11 o9o u57 12JiO 21gt 26-77middot74

-45 26sect ~middot91-912 $69 091 sas 25 middot3 1)0$ 196 2J-8 1-9-1) 220 098 426 2)9 178 1390middot 84 16 6

0 0

Appendx C CALCULATED DATA (Continued)

Turbine Run Generator Generator lurbine Turbine Eft1e1eney Turbine lurbine Spee1f1c

Number Output Losses Outit Input Speed Output SPed middot k_-V KW R _ H_bull_P Percent r Thm HP rpm_ (9) tlo) 11) middot (12 _) (lJI ( ) (1$ (14)

2-9-1 9--46 055 1)62 258 528 580 164 2-9-2 1024 056 248 58 4 665 4 9 191iimiddot48 4~middot0 2-9-3 1132 067 05 2$0 641 795 52q 237 2-9-4 1148 065 1027 2$1 -~8 845 525 252 2-9-5 11 77 oso 16-83 253 6 910~ 522 270 2-9 6 1122 071 1600 251 622 960 47-5 2722-9-A 1092 015 1562 257 608 1010 445 2z12bull9- 1052 079 1514 261 580 1060 41middot7 2 2 2middot9-9 986 o82 ]429 26) 542 1105 372 277 2-9-10 915 086 1340 268 500 1160 334 27-6 2-9-11 638 087 972 254 )81 1270~ 229 250 2-9-12 )28 090 828 259 )19 1295 179 226 2-9-13 192 094 383 2$ 6 150 1370 7 3 152

-3 0

Page 30: The Effect of A Variable Draft Tube Flow Area on the

Chapter IV

A E9J11pment

ih turbine used in this test is lJ 5 1nch Pelton

reaction turbine with a rated output ot 30 horsepower under

a head of 56 feet at a speed ot 720 reYolutiona per minute

Views of this turbine are hovn in Figures S and 6 The

turbine is installed on a concrete pad located over an open

channel in the Hydraulics Laboratory at Oregon State Colshy

lege The date of manufacture of this turbine was 1915

The water was delivered to the turbine from a sump

reservoir by two pumps operating 1n parallel Each pump 1a

an 8 inch Pelton double suction centrifugal pump witb a

rating of l$00 gallons per minute at a head ot 75 teet with

a speed ot 1175 revolutions per minute Tbe inlet tlange

ot tne turbine is $pprox1mately 18 feet above the center

line of the pump

A direct current generator was coupled to the turbine

to receive tne power d veloped as shown in Figures 4 and 7 The generator is a Spr gue Electrodynamometer rated at SS horsepower with a speed range of 7$0 to l$00 revolut1one

per minute The classification is type LO 26A 2)0 volta

Figure 5 - View of Test Turbine

Figure 6 ~ View of Test Turbine

and 149 amperes lbe generator ti ld was aepar tely

excited using direct current from a motor g n r tor ampt

(l$ p 4~8)

The power output of the generator waa dissipated in

the water rheostat (3 p 488-489) shown in Figures 9 and

10 The galvanized tank contain d water ot variable d pth

on an electrode ot cast iron m aauring 1bull x 1 x 1

In the initial installation of the turbine it was

intended that the power output should be measured with a

Prony brak bull For th purpoa68 or this teat it was decided

that the brake was too instable and the generator was

substituted The platform for raising the generator the

nee asary two teet for alignment was built out of available

material In this case heavy laminated wood blocks reiashy

torced with other timbers were used and bolted through the

concrete deck (11 Pbull 36-$7)

Due to the light concrete deck the lack ot mas in

the platform and the slight misalignment in the flexible

coupling ao e vibration waa encountered It seemed to

ncr aae linearly to a maximum at the speed of bout 750

revolutions per minute Above this speed no vibPation was

noticeable The vibration waa not se~ere and does not

appear to have materially affected the test results

26

B Intrumentat1on ~ eaeur1ng Devices

The pressure head at inlet to the turbine vaa meaave4

bymeane ot two )6 inch waterbullmeroury manometerbull connected

in series as shown in Figure 8

The terminal voltage ot the generator vas meaeured by

a laboratory voltDleter with a range to )00 yolta and callbull

brated to within 15 Yolta

The armature current bull and hence the line current was

measured by a laboratory ammeter with a range to 150 amperea

and callbrated to w1 thin o 7S amperes

Tae rate ot tlow was established by weight and time

meaeurementa The weighing ank has a capacity ot 121 000

poundsJ the weight belng indicated by Toledo direct reading

scales Timing was done with a hand atop watch with clivibull

aion ot 02 second

he ~ater level in the tailrace was dete~1ned by a

hook gauge lhie was read to the nearest 001 toot

The turbine and generator speeds were eaaured by a

hand tachometer The technique of almost cont1nuoua readbull

ings of the speed gave an error ot no more than 5 revolubull

tiona per minute

c Operational Procedure

Atter the water level in the aump was checked to

insure an adequate auppl7 the puapa were primed and

27

Figure 7 - Test Generator and Plattorm

Figure middot8- Instrument Board and Field Rheostat

28

started After venting they were valved for operation 1n

parallel

The motor generator set was started to supply the

field current and the circuit breaker was closed Water

wa added to the water rheostat to the level shown in

Figure 10 ~ field current wae minimized by cutting in

all the f ield resistance in the field rheostat of Figure 8

The l2 inch gate valve shown in Figures 5 and 6 waa

slowly opened and the turbine and generator brought up to

speed The 12 inch gat valve and turbine were vented and

the pumps were checked to insure neither had lost ita prime

lhe water rheostat offers very steady load 1f the

water level is essentially constant and the water temperabull

ture 1a fixed () p 488~89) In order to maintain this

constant temperature it was decided not to circulate the

water in the rheostat but rather to allow the water to

boil thua achieving the desired result A standing wave

was set up on the face ot the electrode by the boiling

action but a atable load was eatablished except at very

low water leYels where th11 agitation led to fluctuationa

in the line current

After putting the turbine and generator on the line

maximum power was dissipated in the rheostat by redueing

the turbine speed to between oSO and Soo revolutions per

minute Salt vas added to the rheoetat wat r to increasemiddot

29

Figure 9 - View of Water Rheostat

Figure 10 - View of Water Rheostat

Separate Field ExcitationFrom Motor-Generator set Compound Water-Mercury

---shy

re Manometer

I Q)

~ 0

~

Book Gauge

Open Channel

I

Slap Reservoir

Figure 11 - Wat~r Flow Diagram and Electrical Layout

31

waiting pe~iod ot perhaps an h~ followed

while the boiling point or the water wbulls reacbe4 During

this ti+ne the manometer was vented end eheoked electrical

measur1ng 1nstlUments were connected end the hook gauge was

adjusted tor elevation

It required about two- houtte tor the generator to reach

its normal operating tempe-ratu~e_ After the water in the

rheostat and generator had reached their operating temperabull

turea it was possible to begin the taking of data

The only vaPiable which was controlled wee the turbineshy

generator speed However the upper l1ut1t of safe line

current was slightly over 100 ampJilPampPes and the eireuit

breaker would open when the current reached lOS ~ere bull

Control was exercised by means ot regulating the water

level and salt 1n the water rheo tat and the res1stsnoe of

the tield rheost t~

The etfeet ot each type ot regulation on the three

variables is shown below

Volta Aaperebull Speed

Inc Dec Inc Dee~ Inc Dec

Wa~e1 Level Inc Dec~ X

X X X X

X

Salt Concentration

Inc Dec X

X X X X

X

field Resistance

Inc Dec

X X

X X

X X

32

Jlot all methods gave the ame amount ot change in a

given variable and a period of experiment and trial led to

the following scheme starting the rune with the lowest

turbine speed the water level was high with a high amount

ot salt and the field resistance was cut completely out

Aa it became necessary to increase the speed tor each

aucceasive run either cutting in t he field resistance

decreasing the salt concentration or lowering the Vater

level would produce the desired result However decreasbull

1ng the salt concentration had to be done Without a net

gain in water which led to a tluahing procedure that was

not particularly good because cold water was introduced

which required time to heat to the boiling point Cutting

1n additional field resistance was a good method but th1a

increased the amperage possibly to the point of opening

the circuit breaker Lowering the water level was aatiashy

factol1 until the level got too low causing the current

fluctuation previously mentioned Actually it turned out

that a combination of lowering the water level and cutting

field resistance in would carry the speed from ita minimum

to 1ts maximum value it the proper choice were made each

time the speed waa to be changed At the conclusion of

each aet of runs at a high speed the water level would be

low and the field resistance high

33

TURBINE

PAD AND DECK

TAILRACE

WATER SURFACamp

CONCRETE

DRAFT TU1B INSERTS

7 5( DRAFr TUBE

FLltJI ARIA

5~ DRAFT TUBE

FLOI ARSA

Figure 12 - Sketch of Draft Tube and Test Inserts

34

Figure 13 - View of Draft Tube Insert

Figure 14 - View of Draft Tube Insert

D c __ ~s_middot hedu_le of

A number was assigned to each run The fi~st number

applies to the draft tube tlow areas

1 bull 100~ flow area or 0~ oonatriction

2 - 7S tlow area or 2$ conatr1ct1on

3 SoC flow area or so~ constriction

The second number refers to the wicket gate openings

9 over gate opening

6 bull intermediate gate opening

4 bull one h lt gate opening

The third number 14entif1ea the location of the particular

1Wl in a set ot rona made at a given dratt tube tlow area

and wicket gate opening

fnua run number 1bull4bull10 would identity this as the

tenth run ot a set made at halt gate with 75 ot the draft

tube t1ow area

Rune w re made tor a g1yen dratt tube condition

Firat tor tull 41-aft tube flow area seta ot rune were

made for the overgate halt gate and intermediate gate

conditione An insert was placed in t he draft tube and

rune based on the same gate conditions were made tor the

7S~ draft tube flow area case The insert was then changed

to allow only $~ draft tube flow area

The inserts are sketched 1n Figure 12 and photographed

ln Flgurea 13 and 14 They oonaisted of circula~ segments

36

or l2 ineh plywood mount 4 on wooden legs 10 inches high

The 1nse7te were placed in position and secured by th use

ot a-clamps on the legs and the outside ot the bottom of

the draft tube The obvious disadvantage to this method

waa the neoeasity tor draining the water from the tailrace

tor a change ot 1naert The advantage vas of course the

simplicity ot design and construction

Chapter V

DATA-A Original Data

The normal data-taking crew consisted or two men

Assuming adjustments having been made to secure a certain

turbine speed (aee section on Operational Procedure) one

man would take semi-continuous speed readings with the hand

tachometer until a state or rotational equilibrium was

reached This could be only a period or two minutes up to

ten or tifteen minutes As soon as steady speed was

assured the data taking would begin The second man went

to the weighing tank Where a minimum ot three weighingamp

were made The requirement was to get three consecutive

readings such that the ditterence between tbe smallest and

largest time did not exceed 04 seconds The time to

collect a given weight ot water was then assumed to be the

arithmetic average of the three times He then went to the

hook gauge determined the hook elevation and then

recorded the data on the data sheets The first man meanshy

while had taken readings of the line voltage line current

and manometers and checked the turbine speed by multiple

readings During the length of the run all values were

38

checked to determine mean values for recording

The minimum length of one run was about five minutes

If one or more measure ants tended to drift during the run

all values wer discarded and a new run began as soon aa

qu111br1um was stabl1shedo

B -0-al_e_u_l_a_t--d Data

The h d on the tu~bine 1 defined by

($)

The maxtmwm velocity V4 was equal to about o8 tampet per

secon4 which makes it a negligible quantity when converted

into velocity head

An engineerbulla level was used to deterine the d1ffePshy

ence 1n elevation between the compound water-mercury manoshy

meter and the hook gauge Using this value the equation

for turbine bead becomes

where z4 is the hook gauge reading

The rate of flow 1 cent

w weight or water collected average time to collect

The inlet velocity v1 vas calculated by dividing the

weight rate or flow by the specific weight of water and the

)9

area ot ~e inlet pipe This was equivalent to dividing

the weight rate of flow by 490 Then the power input to the turbine is equal to

WHpin rri

10 (6)

Also

(P ~ut) Turbine

(P out) + Generator

(P lost) Generator

The power output of the generator is simplJ the

produot ot the terminal voltage and the armature (line)

curPent The power lost in the generator can be subdivided

into copper losses and stray power losses lo evaluate

these cunes based on losses of an identical generator

11leampsured by the Department ot Mechanical Engineering were

used The loss curves are reppoduced in part in Figures

15 and 16

Determination ot generator losses proceeds as tollowau

(1) From Figure 15 detem1ne the vo1tage drop in the

armature circuit using the temperatures of 1220 F and the

meaaured current

(2) The induced voltage is t~e sum of the terminal

voltage and the voltage drop 1n the armature circuit

() Entering the induced voltage and the turbine speed

into Figure 16 the stray power loss can be determined

(4) The copper lose can be evaluated from Figure 1$

using the measured current and the temperatlll-e of 1220 P

40

25 ~------~--------~--------~------~

U) -U) - 20

f-4 ~

-~ -gt 0

0

VOLTAGE DROP

~ - i -

- bullbullbull bull - -middot-middot -+ ~- + -t--+ ~ - ~ middotbull ~-~ middott- -+----- _ -4 middotmiddot- --~-+-t---r~~ ~--+t-t- - ---t-c-++~-ulf--

0 50 75 100

Figure 15 - Curves of Generator Voltage Drop and Copper Loss

41

1200

1000

800

600

800

0

0

~-

middot--~ 1shy --1 + bull l

100

I -

150 200

IIDOOED VOLTAGB (VOLTS)

Figure 16 - Curves of Generator Stray Power Loss

_ j

-bullshy -L---- shy middot -shy

250

- r

42

(5) The generator los os equal the sum of the eopp r

loss and stray power loss

~e efficiency or the turbine is taken as

etticiency u e =P out (8)Pin

~ample pound Determ1n1gg turbine Power Output

The following data are taken trom that ot Run 1-9-1

Line voltage 1040 volts Line current 870 amperesSpeed 355 revolutions per minute

The induced voltage 1a determined as follows

Line voltage 1040

Voltage drop 90 using Figure 15 with line current of 870 amperes and temperature ot 122 degrees)

Induced Toltage 1130 volta

The power output of the turbine is determined as follows

Generator output 90$0 (line voltage z line current)

Oopper loss 7 (using Figure 15 with line current of 870 amperes and temperatUe or 122 degrees)

Stray power lose 470 (using Figure 16 with speed ot 355 revolutions per miDUte and induced voltage or 1130 volts)

Turbine power output 9527 vatta

or turbine power output 1s 12z2 horsepower

43

The conversion of the calculated data to a constant

head is based on the conventional assumption of constant

efficiency regardless of turbine head For a constant head

ot 81 teet a purely arbitrary figure the tollowing relashy

tionships are ass1lJiled to be true

I ____L (9) (i)l72

(10)

For these two values the specific a peed may be combull

putedt

N t Jt VPt (11)8 243

Chapter VI

~RESULTS

A -Pr_e_ae_n_t_a_t_t_o~n g Reaultbull

Graphical presentation ot the results ot this te1t

are given as follows

Figure 17 -Turbine characteristics with 100~ dratt

tuba 1low area

Figure 18 - Turbine characteristics with 7S dratt

tube tlow area

Figure 19 bull Comparison ot power and etticiency at

over gate conditions between 100 and

75~ draft tube flow area

Figure 20 bull COZQparison of power and ettic1ency at

halt gate conditions between 100~ and

7S~ draft tube flow area

Figure 21 bull Comparison of power and etticiency at

over gate condition between 100~ and

So dratt tube tlow area

Figure 22 - Comparison in variation ot apec1t1c

speed between 100 and 75~ dratt tube

tlow area

50

45

20

-bull - 1--shy40

bull J-~ 30

~ ex

~ 20

~~ ~ -)q

I

~ - _

- -

10~ OF DRAFT TUBE FL(Jif AREA

CONSTANT HEAD OF 8l FEST10

POIER OUTPUT EFFICIENCY SPECIFIC SPEED

0 ~--------------_--------~------~------~ 400 600 800 1000 1200 1400

TURBINE SPEED (RPM)

Figure 17 - Turbine Char~cteristics with 100 Draft Tube Flow Area

50

46

-bulllle

~ 7 ~ OF DRAFt TUBE FLOW AREA

0 -~~-rl C05STAMT BEAD OF 81 mET 1J~

POIER OOTPUT ---+- ---o ~_H EFFICIDCY ~ I shy

bull ql SPECIFIC SPEKD - ~ -

bull ~ J 10 L rmiddotr- r- -

bullz- I

~~ 30 ~~--~----~~-

20 ~ ~ middot-shy

26

~~ 25

~0 ~r-----i (

Tbull -bullshy

400 600 800 1000 1200 1400

TURBINE SPEED (R PK )

Figure 18 -Turbine Characteristics with 75 Draft Tube Flow Area

47

EFFICIENCY 60

1-----shy

-~ 50~--~--~~-~middot middot middot middot r~-~----~~~~---4~-r~-~~gtt

II

POWER~ J ~ bull bull

u I

sH

40~------+-------+---- -~~--~~-~~~~

~----~rl 1 bull

I

I

0~--------------~------_------~--------

~ -OVER GATE CONDITION

COIJSTANT HEAD OF 81 FEET

0 o 10~ DRAFt TUBE

_-- _ 7~ DRAFT TUBamp FLON AREA II

10_~-----+--------r-------r----~~

400 600 800 1000 1200 1400

TURBINE SPEED (RPM)

Figure 19 middot - Comparison between 75 and 100 Draft Tube Flow Areas of Power and Efficiency at Over Gate Conshydition

48

t

bull --4 r ~- ~ middot~

70 1-----------+-~~~~~+middot ~ ~~ middot middot -~~--~~--------~~----~-+1

-~-

Atbull bull

lla-

60

amp0

40

20

10

oampOO

t _ - - ~-+- - -~-

l2 GATB COJIDITIOJJ

COJISTABT HJW) OF 81 JBET

o 0 lOQ( DRAFl TUB8 FLOI AREA

e-- - e 75 DRAFT TUBE FLOW AREA

800 1000

- r-

~

TURBIbull SPBIID (RPII)

Figure 20 - Comparison between 75 and 100 Draft Tube Flow Areas of Power and Efficiency at Half Gate Conshydition

49

60

50

-40

bull 30

IIQbull

20

10

0

400

- t - ~

EFFICIENCY

_J bull - bull bull

~ r r middot t -+ shy L -t -

OVER GAD COliDITIOI

CONSTABT BEAD OF 8l FBB

o o 10~ DRAFt TUBE FLOI ADA middot--- 5~ DRAF TUBE FLQPi AREA

600 800 1000 1200

Figure 21 -Comparison between 50~ and 100~ Draft Tube Flow Areas of Power and Efficiency at Ove~ Gate Conshydition

50

25

20

15

10

0

Figure 22

~- T -4 -t- -l --~-

t-~ I

middot --~- t ~---- _ __ _ + --

----~- --r-- --

~-=J-~-=-~ -==~ _ ~- -- ---f---1 - shy

CONSTANT HEAD OF 81 FEBT

o--o 1~ DRAFT TUBE FLltll AREA

75C DRMT TUBK FLCIJ AREAmiddot--middot-middot 600 800 1000

TURBINE SPEED (RPK)

Comparison of Specific Speeds for 75 and 100 Draft Tube Flow Areas

51

B Discussion 2 Result

Consideration of Figures 17 and 18 indicates the

overall eftioi ncy pattern or hill is significantly or

rounded for the 7$~ flow area than for the 100~ flow area

bia implies a greateP efficiency is possible at speeds

leas than or greater than design speed with an insert in

the draft tube However the muilDum efficiency is lemiddotas

Direct comparison at over gate conditions is made in

Figure 19 ~e same general trend is noted tor both the

etticiency and power curves for the 7$~ flow area case

The eurves show higher values at overspeed than do the

correaponding cWvea for the 100 flow area case It ia

not clear whether the curves have been shifted by the dratt

tube constriction or whether the curves simply bulge past

the normal curves at both overspeed and underspeed condishy

tions The power curves apparently peak near the aeme

point bullalthough maximum power is still obtained with the

normal draft tube area

For the comparison at halt gate operation shown in

Figure 20 a general improvement has apparently been made

by restriction of the draft tube flow area At every speed

the etticienoy and the power is greater for the restricted

tlow case The two ett1o1ency curves and two power curvea

are practically parallel throughout the speed range ot

teat

As the flou aroa i e decreased still farther a s1gn1

ticant change appears Reterr1ng to Figllle 211 tor the $0

flow area curves it a obvious that exit losses have

become excessive at the overgate condition because the

efficiency and power are everywhere leas than tor the case

of normal draf t tube area

Earlier it was pointed out t hat 1t the r esult s 1nd1bull

eated an increase in both power and ef tieiency- t hen it

could be assumed tha t the additional los s i ntroduced with

the draft tube insert is less than the diminished losses

due to leas shock losa and water passage losses For the

places where both the efficiency and power have been

increased we can assume that the insert has improved turshy

bine performance

For the places where the power haa been decreased

nothing can be said as to the elimination of ampbock loss

because the new lose present with the drat tube insert has

overshadowed any gains in eftecti Ve head upatJ-eam of the

insert

Near the peak of the efficiency hill howeve~ it may

be pointed out t hat shock loaa ie a minimum with a normal

draft tube and the insert merely adds an additional loss

with the resultant decrease in maximum efficiency tor the

7$~ flow area case

Perhaps the most s1gn1ticant set of eurves is shown aa

53

Figure 22 In this graph values of specific speed tor the

75 and 100~ flow area cases for both over gate and one

halt gate openings are plotted against turbine speed At

every speed and both gate openings the value ot specific

speed for th 75~ flow area case is greater than that for

the 100 t1ow area ease

Since the head is a constant for both situations this

may be interpreted in either of two ways trom equation

(11)

(1) For the same turbine apeed restriction of the

draft tube t1ow area resulted in greater turbine power

(2) For the same power amputput the turbine with 75~

draft tube flow area operated at a greater speed than did

the one with 100 flow area

Since the required diameter of a turbine varies

inversely with the speed the second interpretation could

be stated such that a smaller turbine could be used to

develop the same power output

Whether viewed trom the aspect of increased power

greater speed or reduced size the performance of the turshy

bine with reduced draft tube flow area is superior to that

with the nolmal flow are in the draft tube

The curve of specmiddotific speed versus turbine speed for

the so draft tube flow area case at over gate cond1t1ona

was not included in Figure 22 This curve lies below that

for the 100~ flow area c se at all speeds

In elaboration ot the second interpretation of Figure

22 attention is directed to the relative magnitudes ot

increased apee1f1c speed tor the two gate openings Assumbull

ing that the increase in specific speed implies a shift ot

the power curve to the right along the turbine speed scale

the power curve would be shifted more tor tbe halt gate

opening than tor the over gate opening

It thia trend could be extrapolated to the other gate

openings the tendency can be seen tor the line ot beat

speed to rotate toward the line of the operating speed as

illustrated in FigtU-e ) The advantage of this has already

been discussed

This particular turbine has a low specific speed tor a

reaction turbine Aa the rated value of apecitic apeed tor

reaction turbines increases the line ot beat speed departs

even more radically from the line of operating bullpeed It a

test similar to this were conducted on a reaction turbine

ot gleater specific speed it is pJobable t hat the rotation

ot the line of beat apeed would become more p~onounced

The scheme used in th1a teat had two obvious dr wbull

backs The first was the decision to leave all the wicket

gamiddottes installed tor all conditions ot the draft tube

These gates predominated in control of the tlow The

inserts added to the draft tube merely acted as auxiliary

55

contrGla

The aecond drawback was the choice or device to place

in the draft tube The reasons foll selection of this type

of device have been previously mentioned It is to be

anticipated that adaptation ot dratt tube flow control

would result 1n a better device for an actual turbine

installation Such apparatus might take the form of a

pneumatic bladder or a h7drau11oally operated variable

venturi section in the draft tube It is conceivable that

the gate as used in this test might be adapted also

Chapter VII

OONCLtJSIOfS

From the results of this test the following eonolubull

e1ona aa to the effect ot a variable draft tube flow area

on the performance or a r action turbine may be drawn

(1) The effect ot a variable draft tube tlow area 1a

generally favorable upon the operat1Gn ot a reaction turbull

bine because or the tendency tor the line or beat speed to

rotate toward the line ot operation This resulte in

better performance of the turbine at partbullloads

(2) he etf1o1ency eh111 tor the turbine beeomaa JDore

tlat at the top leading to a smaller max1JilWD effic1enc7

but e reater etticieney at other pointe of operation with

the insertion ot an auxiliary control ror the rate ot tlov

in the draft tube

(3) The power output of the turbine will increase at

over speed over gate conditione as well a at part gate

conditions with the proper amount or draft tube eonatr1cbull

tion or flow

(4) It is possible to eliminate at least partially

eddy type shock loss by tho introduction ot flow control

in the draft tube

BIBLIOGRAPBl

1 Addison Herbert A treatise on applied h-draul1cs New York Wiley 1954 724 Pbull

2 Allen o M and I A Winter middot Co111parative testa on experimental draft tubes Tranaact1ons ot the American ociety ot Civil Engineers 87t893bull970 1924

3 Barrows a E Water power engineering 3d ed ew York McGraw-Bill 1943 791 Pbull

Bovet G A Modern trenda in hydraulic turbine design4middot in Europe Tranaactions of the American Society ot Mechanical Engineera 75975bull993 1953bull

s Oreager William P and Joel D Justin Hydroelectrichandbook 2d ed New York Wiley 19$0 1151 Pbull

6 Daily Jamea w Hydraulic machinery Int Hunter Rouses Engineering hydraulics Hew York Wiley 19$0 p 8$8bull99

Daughertybull Robert L Bydraulie turbines ew Yorkbull7middot MoGrav-Hlll 1920 281 Pbull

8 Daugherty Robert L Inveat1gat1on of tne performance ot a reaction turbine ~anaactiona or the American Society ot Civil Engineers 7811270bull1304 1915

9 Davie L M Model and prototype testa Int Trend in hydraulle turbine practice symposium lranaactions ot the American Society ot Civil Engineers 1o63S3middot368 1941

lfJ Doland James J Hydro power engineering Hew Yorkbull Ronald 1954 209 Pbull

11 Gandy Theodore s and Elmer c Schacht Direct curshyrent motor and generator troubles operation and repair New York McGraw-Bill 1911 293 Pbull

12 Gibaon Arnold H Hydraulics and ita applications5th ed London Constable 1952 813 Pbull

58

13 Button s P Component loases in Kaplan turbinebull and The prediction of efficiency from model tests Probull coedings of the Institution or Mechanical Engineers168743-762 1954

14 Knapp R T~ Oavit t1on mechanics and its relation to the d sign or hydraulic equip ent Proceedings or tne Institution ot Mechanical Engineers 166150bull16) 1952

15 Langsdorf Alexander s Principles of direct curHnt mach1nee 5th ed New York r~cGrawbullH1ll 1940 746 Pbull

16 Lsrner Chester w Characteristica of modern hydraubull lie turbines Trans e~ions of the ~~erican Society ot Civil Engineers 66306-386 1910

17 Linsley Ray K Jr and Jobulleph B Franzin1 Eleshyments of hydraulic enginebullring New York McGrawshyBill 19$5 $82 Pbull

18 Mead Daniel w Hydraulic machinery llev York McGraw-Hill 1933 396 Pbull

19 ead Daniel w Water power engineering New York McGrawbullRill 191S 843 Pbull

20 Mockmore Charles A Part gate operation at water turbines Corvallis Oregon State College Department ot Civil Engineering 1933 11 numb leaves (Unpubshylshed typescript)

21 Mockmore Oharles A Flow characteristics in elbow dratt tubes Transactions of the Amez-ican Society ot Civil Engineers 103402middot464bull 1938

22 Moody L F Hydraulic machinery In c v Davis Handbook ot applied hydraulics New York McGrawshyHlll 1942 1082 Pbull

2) Ptau At-nold Hydrbullulie turbine handbook ld ed Milwaukee AllisbullOhalmers ManufactUIing Company 1948 70 Pbull

RheingalUI w J Recent developments in Francis turshybines Mechanical Engineering 74189-196 1952

25 Russell George E Hydraulica 5th ed New York Henry Holt 1942 466 Pbull

26 Safford A and E P- Hamilton American mixed tlow turbine and ita setting Tranampactions or the Amerieal Society of Civil Engineers 851237bull1)56 1922

27 bull Spannhake W1lhe1Dh Problems or modern pump and tur b1ne design Transactions of the American Society of Mechanical Engineers 56e22$-248 1934bull

28 Sutherlandraquo R A Better ethod or representing and middot tudying water turbine performance ~ansaetions ot thmiddote American Society of Mechanical Engineers 68t675bull 686 1946

29 Teats ot five models or draft tubes tor turbines Engineering News-Record Pbull 182-184 Aug 2 1923

30 White w M American hydztaulic turbines Mechanical Engineering S2t390bull39S 1930bull

31 White w M lhe hydraucGne rega1ner1 its developmentand appl1eat1ons 1n hydroelectric plants Meohanlobulll Engineering 43t37Sbull380 1921 middot

32 Winter I A Economic principlebull in designbull Int Trend in hydraulic urbin practice bull a ampoeiumTranaaot1ona ot the American Society ot Civil Engineerslo6332bull3S2 1941

33 Wiel1cenua G F Fluid mechan1ca or turbo-machineryNev York McGraw-Hill 1947 613 Pbull

APPENDICES

c

Appendix A

NOATIOB

A Angle between the absolute velocity vector and the tangent to the rwmer Subscripts 1 and 2 refel to entrance and exit ot the runner blade

B Angle between the relative 1elooity vector and the tangent to the rwmer Subscripta 1 and 2 refer to entrance and ezit or the runner blade

Angle between the tangent to the runner blade tip and the tangent to the runnel- Subscripts 1 and 2 reter to entrance and exit of the rt1rmer bladebull

Blade angle-gate opening conetant defined by equation (1)

e 09erall efficiency

g Gravitational acceleration assumed constant at 322 teet per second per second bull

H Turbine head detined by equation ($)

m Exit loss coeft1e1ent

Turbine speed expressed in revolutions per minute

Turbine speed under a constant head of 81 teet

specitic apeed of the turbine under a constant head ot 81 teet

p Power output in horsepower ot the tvbine

Power output of the turbine Ulder a constant head ot Sl teet

Pl- Pressure head at entrance to the tUlb1new

l1 Peripheral velocity ot the runneP Subacr1pta 1 and 2 refer to entrance and exit ot the JUnllampr blade

62

v Relative velocity reaulting trom the combination ot the absolute water velocity V and the runner periphshyeral velocity u Subscripts 1 and 2 refer to entrance and exit ot the runner blade

v] Relative velocity vector necessary to produce a tanbull gential entry into the runner blades

V Absolute water velocity Subscripts l and 2 refer to entrano and exit ot the runner blade

v2 Velocity head Subscripts 1 and 4 reter to the ~8 entrance to the turbine and the tail~ace wate~

w Unit weight ot water assumed constant at 624 pounda per cubic toot

V Weight rate ot flow in pounds per aeooncl

XX Velocity component ot ahook See Figule 2

Z Elevation head Subscripts 1 and 4 reter to entrance to the turbine and the taibace water surfacebull

Appendix B ORIGINAL DATA-Run

lfwnber

0-4-1 0-4-2 0-4-3 o-4-4 o-4-S o-4-6 0-4-7 0-4-8 0-4-9o-4-lo o-4-11 o-4-12 0-4-13

o-6-1 o-6-2 06-3 o-6-4o-6middotS o-6-6 o-6-7 o-6-8 0-6-9 o--6-lo o-6-11

Speed

rmiddot2middotbullmiddot(1)

336 38$ 451 S$9 620 669 6lt)$ 120 787 860 932

102imiddot109 bull

352 355 443middot 543middot 620 654AJs32

911 1001 1111

~essure Head rt (2)

410 410 416 426 431 43-7 439 44-9 452 467 482 soo $1 bull $

350 351 35middot7 )66 37-9 37-9 392 41 bull 3 43middot3 460 489

Elevation Bead

fjj $7 $7 $7 $7 $7 $7 51 57 5-15858 $8 58 56 56 $6565656 51 575As5a

Velocit Head

flj 07 07 07 06 06 06 06 os 05 os0404 03

09 09 oa o8 o8 os 07 07 06 o~o

Total Head rt ($)

47middot4 4A44 o 489 49-4 soo $02 $11 $14 $29 5imiddot45 2 576

41 bull $ 416 421 430 44middot3 44middot3 456 47-7 496 523551

Plow

lbtjec

326 324middot317 311 306 30029middot28 middotmiddot middot 386 275middot260 240 218

359 36~35 bull 349 345middot 339 330 318 300 273 240

Line Potential

vyqjbull 1060 1220 ~-0o 1920 2150 2000 2$60 2000 1940 18)015io11 o

1000 1100 139bull5 1760 1925 16$0 1620 1610 1540 1330 870

Line Current

amlscs 960 900 830 740 730655 70bull 0 530 660 600 5imiddot54 6 )60

982 930 860 780 ~3-545

79-5 74-5 670 560 370

P

Appendix B ORIGINAL DATA (Continued)

Run Number

Speed

Pbulltmiddotbullmiddot )

leasure Head ft(2

Elevation Head tt(J)

Velocity He-dfmiddotj

Total Bead tt($

Flow

lbstsec( )

Line Potential vo~ta( )

Line Current

amjs (sect

0bulllt)-1 0-9-2

3ll6 398

28o ~~1

$6 56

1o 10

346 347

390 365

1ooo 1190

aao 835

0-9-3 0-9-4 o-9-S

472 565 632

292 305 312

$6 s6 56

10 o9 o9

)$8 J7~o 37~7

381376 37o

1)6614oo 141o

820 ass ass o-9-6 0-9-7 0-9-8 o-9-9 0middot9-10

680 120 762 844 920

)24337346 366 390

56 $6 56 57 $7

09 os o8 oa 07

)89401 410 431454

367~ 357348 34o 322

1400 1J6o l36o 1310 1170

843 820 7957So 67~0

0-9-ll 0-912

1001 1100

41 bull 7 45-3

s 7 6~0

06 os 480 $18

299 268

980 65$

560 36~5

1-4-1 1-4-21-4-l1-4shy1-4-5 1-4-6 l-4-7 1 4-8 1-4-9 1-4-10 1middot4-ll 1-4bull12

354middot452 562 62q 674shy102 752 760- 863 932

1022 1100-

)82389 4014oa 416 41--7 423 428 44-2 45-7 486 49-2

51S757 51 5-7 5middot15zs sa $8 58 59

07 07 06 06 06 06 06 os o bull o 04 o J

446 45-)46middot4 471 ti7-9480 q86 491505 $19 548 55-4

)28 320 311 306 300 295 291 286 269 2582iimiddot21 bull

1080 14Lo 1550 153-5 1470 141-0 1385 1310 1310 1230 1120 855

970855 875 91-0 94~0 975 966 995 860 77-S 610 4fo

0 ~

Appendix B ORIGINAL DATA (Contirmed)-Run Speed Pressure Elevation Velocity Total Flow Line Line

Number Head Head Head had Potential Current rtjjmbull t~ bttec vyfs am~a12) ( ) ti fli 8

1-6-l $6 33$ $6 0bull9 400 364 1100 93 0 1-6-2 41 34laquo2 $6 oa 406 JS7middot iios a5s l-6-3 500 3~0 5bull6 os 356 1 1 o aos 41middot~1-6~4 35bull4 5-6 oa 41middot 352 16~0 82 0 5~1-6-5 5 bull 36_2 Sbull6 08 42bull6 349middot 161 ~ 0 86~0 1-6-6 622 366 $6 oe 43bull0 345middot 158 0 88~$ 16-A 649bull 37bull1 56 os 43-S 342middot 1570 895 1~- 386 57 07 46-0 192 ) 125A44 333middot 1-6-9 3) 404 5middot1 07 468 317 1620 675 1610 911 42-4 5-7 o6 48-7 298 168 0 61 0 1-6-11 999 451 56 os Sl ll 276 ~2-0 530 1-612 1115 485 58 04 54middot7 238 90 )3 0

1middot9-l 355 279 56 10 )45 385 1040 870 1-9-2 399 28J $6 10 )49 38$ 1140 86 5 l-9-3 ~ ao 291 56 ~0 35middot1 J8J_ JJ6o 815 1bull9-4 579 303 56 09 )68 375middot J4JO 830 l-9bullS 40- 313 )6 09 31middot8 370- 1460 82~0 1-9bull6 679 2) 56 09 3 bull8 364middot 1670 710 l-9-7 682 319 56 o9 384 ) 62 1460 79 5 l-9-8 724 33middot5 56 o8 399 3$6 bull 1480 76 -5 1-9-9 762 34middot3 $6 0 bull 8 407 )48 14910 13middotS 1-9-10 833middot )60 5middot7 os 42$ 339 144$ 686 1-9-ll 926 39middot1 5-7 07 455 318 1290 600 1-9-12 1000 41middot3 0-6 476 298 1115 510$ ~ 1middot9-13 1105 452 s o4 $14 2$6 710 )10

~

Appendix Bt ORIGDIAL J (Continued)

Run Speed Pressure Elevation Velocity Total Plow Line Line Number Head ltead Head jlamp$d P()ten~ibulll Current

r~~~m ft ft lbs~seo voltattj rgj twimiddot t 1 t2gt lt3 ou t ( rt

2-9-1 384 289 S 6 10 35 5 1400 1170 810 2-9-2 443middot 29$ $6 ltimiddot9 360 379middot 11(0 87$ 2-9-J 536 30bull 3 sc 09 )68 374middot 1)40 84 bull) 2-9-4 571 306 $6 09 3~1 372 120bull 0 955 2-9-5 623 316 S6 09 J l )6S UJSo 77$ 2bull9-6 669 327 S6 09 )92 )61 1240 905 2-9bull7 712 )39 56 os 40-3 351 12(0 86 bull0 2-9-8 ~5$~ J48 56 oa 412 348 1290 81 bull ) 2-9-9 04 )63 56 oa 42-7 339 12ltJO 76$ 2middotmiddot9-10 8$2 376 5middot1 07 440 33~- ~ o 710 2-9-11 955 394 5-1 o6 457 300 1100 506 2middot9-12 1000 421 $7 06 48middoti 295 1020 $18 2-9bull13 110~ 463 56 05 $2 267 620 3~0

oshy0

Appendix Gt CALCULATED DAgA

Turbine Run Generator Generator Turbine Turbine Efficiency Turbine Turbine Specit1c

Number OutputKWlt21

Loa~Jes KWlol

Outut K bull (H)

Input RP 12)

middot Percentlt13gt

Speed r~Jmiddot(

0ltput HP ~1

Speed r-m

( 6) middot

o-4-1 0middot4-2 0-4-3 0-4-4 0-4-5 0-4-6 O-qmiddot7o-4-8o-4-9 0-4bull10 0-4-11 o-4-12

1018 1o9a 1220 1)62J40214oa1J4oo 1357 1320 1164 997 718

046 o59 071 092 096 1071oo 134 104 100 109 107

14261sso 17)01948 2008 20322011 1999 19 09 1708 14-84 11o6

281279 27-7 276 215 273271 268 268 26h 258 24-5

soa 555 62$ 705 7)1145 742 74-6714645 51s 45-1

440 sos 585 720 195 sso sao 9$$ 985

1065 1135middot 1230

318 357 319 416 422 419412 39middot9 378 324 260 191

102 12bull4 148 191 21bull 3 22o 233 249 24924middot9 238 221

0-4middot13 418 104 699 228 306 1300 117 18)

o-6-1 982 045 1376 271 $08 496 376 124 o-6-2 o-6-3 G-6-4o-6-5 0-6-6

1023 1200 13 73 J415 139h

051 0middot66 oaa ()bull 96 088

14-39 1696 1958 2026 1986

276 27middot4 273 278 274

$20 61 8 717 7)0726

q95615745 8)5685

390 ll5middot3 sos soo 490

127 170 218 243 2$$

o-6-7 o-6-8 o-6-9o-6-lo

1288 1199 1032 7-45

o9o 094 09$ 096

1846 1733 1511 1128

274 276 271 260

67S 629559 43middot4

980 1085 1165 1245shy

436 )83316 21bull 7

266 276 270 239

0-6-11 322 1oo 566 2141 2JS 1350 101 177 0 --4

Appendix C CALCULATED DAlA ( Continued)-Run

Number Generator Generator

Out2ut Losaes xw LW- 12gt (lO)

Turbine Out2ut

ltPlJ

Turbine Inat lfP Jig)

Etpound1e1ency

PireentDl

Turbine Sed x-~m( 1

Turbine OutEut RPJl)

Turbine Specific

SeeedrIbullntbull

( 6)

o-9middot1 0-9-2 0-9-3 o-lt)-4 09-$ 0bull9-6 0-9-7 0-9-8 0-9-9 0-9-10 o-9-11 0-9-12

aao 994

111$ 1197 1206 1180 11)21081 982 784 5-49 2)9

0middot45oss o6$ 070 07$ 0-77 (l77 or~ o s06o 8 096

123~ 1402 1$80 1698 17bulllS 168$ 16bull18 ~middot5430 1151 a~J4 9

24middotgt24middot3248 25~25 260 260 259 267 266 26middot1 2S2

sos 577 63-7 671 676 650 621 60036J4

327 178

$) 610AlO 3$

92S 980

102$ 1070 1157middot 1230 1300 137Smiddot

44middot4 soo 523 ssomiddot 540so6 46-5 432 368 274 18~8

J46 176 21-1 255 2802s_A 28 289 288 265 231 168

1-4-1 1-4middot2 1-4-3 1-4-4 1-4-5 1-4-6 1-4-7 1-J-8 1-4~9 1-4-10 1-4-11 1-4-12

10bull48 1231 13-S6 1397 1)821375 1))8 1303 1127 953 683) 51

048 067 o7A07 0 bull79 oa1 oss o bullao osa 0lt)0 096 099

J468 1740 1921 1978 1958 19$1 1911 lSSi162 1)98 1045

603

266 264 262 262 261 2512$7 2$6 24middot7 24-3 233 217

551 660 13middot3155 75-6 7~-97 middot4 72$ 67 51middotJ 44middot9 21middot1

475 605 A4220

875middot 910 970_

1000 1090bull 1166 1243 1330

5816

44middot444middot5 430 427 412 392 329 273 188 l0-7

117 101 204 22$ 2)7245 2562sa 257251 222 179

a-C))

Appendix Ct CALCULATED -DATA ( Ocntinued)

1-6middot1 1023 o$2 14-41 26S 505 41~6 26~

54middot5 13middot3l-6-2 1201 067 1boo 625 47-9 17shy~middot41-6bull3 1296 oA9 1 middot43 26 9 700 so5 20bull 4 l-6-4 l3j5 o 0 19~09 268 71bull3 A5o 514 222 1-6-5 1) 5 o81 19(gt4 271 725 51-5 238 l-66 1398 081 198) 27-0 736 8 S13 252~-middot l-6j 1405 083 199i 211 733 885 $middot06 2$9 l-6 13middot9~ 103 2amp 0 279 71 8 985~ 467 ~-69 1228 1 bull 02 17-SS 270 661 109$ 407 ~3~ l-6bull10 1025 100 lSll 26i 573 1175middot 27~S32middot~l-ampu 153 1-00 llft3 26 444 1270 22 24bull8 1bull6-12 294 100 52a 231 22 3 1360 95 172

1-9bull1 904 048 1275 2J4Z $28 S4$ 459 1$2 1-92 98$ oss 13-92 24middot4 57-0 6JO 49bull1 176 1-9middot3 1110 066 1$76 24middot9 63middot4 I2o 536 21-7 l--9-4 1187 072 1685 251 66$ 5 $$ bull 0 261 1middot9-5 llltJ7 1710 25middot4 67-3 93$ 536 28~20-671middot9-6 1186 o 8 1708 25-7 67) 980 $15 2691-9- 1161 oBo 1660 2$middot3 6$6 990 508 29-1 l~- ll-32 oB) 16sect0 2$8 632 1030 471 291 1-9bull9 109$ oa5 2$7 614 1075 29S~middot 0 4imiddot41-9-10 9~91 oas 262 S$1 1150~ 3 o 292 1-9-11 o9o u57 12JiO 21gt 26-77middot74

-45 26sect ~middot91-912 $69 091 sas 25 middot3 1)0$ 196 2J-8 1-9-1) 220 098 426 2)9 178 1390middot 84 16 6

0 0

Appendx C CALCULATED DATA (Continued)

Turbine Run Generator Generator lurbine Turbine Eft1e1eney Turbine lurbine Spee1f1c

Number Output Losses Outit Input Speed Output SPed middot k_-V KW R _ H_bull_P Percent r Thm HP rpm_ (9) tlo) 11) middot (12 _) (lJI ( ) (1$ (14)

2-9-1 9--46 055 1)62 258 528 580 164 2-9-2 1024 056 248 58 4 665 4 9 191iimiddot48 4~middot0 2-9-3 1132 067 05 2$0 641 795 52q 237 2-9-4 1148 065 1027 2$1 -~8 845 525 252 2-9-5 11 77 oso 16-83 253 6 910~ 522 270 2-9 6 1122 071 1600 251 622 960 47-5 2722-9-A 1092 015 1562 257 608 1010 445 2z12bull9- 1052 079 1514 261 580 1060 41middot7 2 2 2middot9-9 986 o82 ]429 26) 542 1105 372 277 2-9-10 915 086 1340 268 500 1160 334 27-6 2-9-11 638 087 972 254 )81 1270~ 229 250 2-9-12 )28 090 828 259 )19 1295 179 226 2-9-13 192 094 383 2$ 6 150 1370 7 3 152

-3 0

Page 31: The Effect of A Variable Draft Tube Flow Area on the

Figure 5 - View of Test Turbine

Figure 6 ~ View of Test Turbine

and 149 amperes lbe generator ti ld was aepar tely

excited using direct current from a motor g n r tor ampt

(l$ p 4~8)

The power output of the generator waa dissipated in

the water rheostat (3 p 488-489) shown in Figures 9 and

10 The galvanized tank contain d water ot variable d pth

on an electrode ot cast iron m aauring 1bull x 1 x 1

In the initial installation of the turbine it was

intended that the power output should be measured with a

Prony brak bull For th purpoa68 or this teat it was decided

that the brake was too instable and the generator was

substituted The platform for raising the generator the

nee asary two teet for alignment was built out of available

material In this case heavy laminated wood blocks reiashy

torced with other timbers were used and bolted through the

concrete deck (11 Pbull 36-$7)

Due to the light concrete deck the lack ot mas in

the platform and the slight misalignment in the flexible

coupling ao e vibration waa encountered It seemed to

ncr aae linearly to a maximum at the speed of bout 750

revolutions per minute Above this speed no vibPation was

noticeable The vibration waa not se~ere and does not

appear to have materially affected the test results

26

B Intrumentat1on ~ eaeur1ng Devices

The pressure head at inlet to the turbine vaa meaave4

bymeane ot two )6 inch waterbullmeroury manometerbull connected

in series as shown in Figure 8

The terminal voltage ot the generator vas meaeured by

a laboratory voltDleter with a range to )00 yolta and callbull

brated to within 15 Yolta

The armature current bull and hence the line current was

measured by a laboratory ammeter with a range to 150 amperea

and callbrated to w1 thin o 7S amperes

Tae rate ot tlow was established by weight and time

meaeurementa The weighing ank has a capacity ot 121 000

poundsJ the weight belng indicated by Toledo direct reading

scales Timing was done with a hand atop watch with clivibull

aion ot 02 second

he ~ater level in the tailrace was dete~1ned by a

hook gauge lhie was read to the nearest 001 toot

The turbine and generator speeds were eaaured by a

hand tachometer The technique of almost cont1nuoua readbull

ings of the speed gave an error ot no more than 5 revolubull

tiona per minute

c Operational Procedure

Atter the water level in the aump was checked to

insure an adequate auppl7 the puapa were primed and

27

Figure 7 - Test Generator and Plattorm

Figure middot8- Instrument Board and Field Rheostat

28

started After venting they were valved for operation 1n

parallel

The motor generator set was started to supply the

field current and the circuit breaker was closed Water

wa added to the water rheostat to the level shown in

Figure 10 ~ field current wae minimized by cutting in

all the f ield resistance in the field rheostat of Figure 8

The l2 inch gate valve shown in Figures 5 and 6 waa

slowly opened and the turbine and generator brought up to

speed The 12 inch gat valve and turbine were vented and

the pumps were checked to insure neither had lost ita prime

lhe water rheostat offers very steady load 1f the

water level is essentially constant and the water temperabull

ture 1a fixed () p 488~89) In order to maintain this

constant temperature it was decided not to circulate the

water in the rheostat but rather to allow the water to

boil thua achieving the desired result A standing wave

was set up on the face ot the electrode by the boiling

action but a atable load was eatablished except at very

low water leYels where th11 agitation led to fluctuationa

in the line current

After putting the turbine and generator on the line

maximum power was dissipated in the rheostat by redueing

the turbine speed to between oSO and Soo revolutions per

minute Salt vas added to the rheoetat wat r to increasemiddot

29

Figure 9 - View of Water Rheostat

Figure 10 - View of Water Rheostat

Separate Field ExcitationFrom Motor-Generator set Compound Water-Mercury

---shy

re Manometer

I Q)

~ 0

~

Book Gauge

Open Channel

I

Slap Reservoir

Figure 11 - Wat~r Flow Diagram and Electrical Layout

31

waiting pe~iod ot perhaps an h~ followed

while the boiling point or the water wbulls reacbe4 During

this ti+ne the manometer was vented end eheoked electrical

measur1ng 1nstlUments were connected end the hook gauge was

adjusted tor elevation

It required about two- houtte tor the generator to reach

its normal operating tempe-ratu~e_ After the water in the

rheostat and generator had reached their operating temperabull

turea it was possible to begin the taking of data

The only vaPiable which was controlled wee the turbineshy

generator speed However the upper l1ut1t of safe line

current was slightly over 100 ampJilPampPes and the eireuit

breaker would open when the current reached lOS ~ere bull

Control was exercised by means ot regulating the water

level and salt 1n the water rheo tat and the res1stsnoe of

the tield rheost t~

The etfeet ot each type ot regulation on the three

variables is shown below

Volta Aaperebull Speed

Inc Dec Inc Dee~ Inc Dec

Wa~e1 Level Inc Dec~ X

X X X X

X

Salt Concentration

Inc Dec X

X X X X

X

field Resistance

Inc Dec

X X

X X

X X

32

Jlot all methods gave the ame amount ot change in a

given variable and a period of experiment and trial led to

the following scheme starting the rune with the lowest

turbine speed the water level was high with a high amount

ot salt and the field resistance was cut completely out

Aa it became necessary to increase the speed tor each

aucceasive run either cutting in t he field resistance

decreasing the salt concentration or lowering the Vater

level would produce the desired result However decreasbull

1ng the salt concentration had to be done Without a net

gain in water which led to a tluahing procedure that was

not particularly good because cold water was introduced

which required time to heat to the boiling point Cutting

1n additional field resistance was a good method but th1a

increased the amperage possibly to the point of opening

the circuit breaker Lowering the water level was aatiashy

factol1 until the level got too low causing the current

fluctuation previously mentioned Actually it turned out

that a combination of lowering the water level and cutting

field resistance in would carry the speed from ita minimum

to 1ts maximum value it the proper choice were made each

time the speed waa to be changed At the conclusion of

each aet of runs at a high speed the water level would be

low and the field resistance high

33

TURBINE

PAD AND DECK

TAILRACE

WATER SURFACamp

CONCRETE

DRAFT TU1B INSERTS

7 5( DRAFr TUBE

FLltJI ARIA

5~ DRAFT TUBE

FLOI ARSA

Figure 12 - Sketch of Draft Tube and Test Inserts

34

Figure 13 - View of Draft Tube Insert

Figure 14 - View of Draft Tube Insert

D c __ ~s_middot hedu_le of

A number was assigned to each run The fi~st number

applies to the draft tube tlow areas

1 bull 100~ flow area or 0~ oonatriction

2 - 7S tlow area or 2$ conatr1ct1on

3 SoC flow area or so~ constriction

The second number refers to the wicket gate openings

9 over gate opening

6 bull intermediate gate opening

4 bull one h lt gate opening

The third number 14entif1ea the location of the particular

1Wl in a set ot rona made at a given dratt tube tlow area

and wicket gate opening

fnua run number 1bull4bull10 would identity this as the

tenth run ot a set made at halt gate with 75 ot the draft

tube t1ow area

Rune w re made tor a g1yen dratt tube condition

Firat tor tull 41-aft tube flow area seta ot rune were

made for the overgate halt gate and intermediate gate

conditione An insert was placed in t he draft tube and

rune based on the same gate conditions were made tor the

7S~ draft tube flow area case The insert was then changed

to allow only $~ draft tube flow area

The inserts are sketched 1n Figure 12 and photographed

ln Flgurea 13 and 14 They oonaisted of circula~ segments

36

or l2 ineh plywood mount 4 on wooden legs 10 inches high

The 1nse7te were placed in position and secured by th use

ot a-clamps on the legs and the outside ot the bottom of

the draft tube The obvious disadvantage to this method

waa the neoeasity tor draining the water from the tailrace

tor a change ot 1naert The advantage vas of course the

simplicity ot design and construction

Chapter V

DATA-A Original Data

The normal data-taking crew consisted or two men

Assuming adjustments having been made to secure a certain

turbine speed (aee section on Operational Procedure) one

man would take semi-continuous speed readings with the hand

tachometer until a state or rotational equilibrium was

reached This could be only a period or two minutes up to

ten or tifteen minutes As soon as steady speed was

assured the data taking would begin The second man went

to the weighing tank Where a minimum ot three weighingamp

were made The requirement was to get three consecutive

readings such that the ditterence between tbe smallest and

largest time did not exceed 04 seconds The time to

collect a given weight ot water was then assumed to be the

arithmetic average of the three times He then went to the

hook gauge determined the hook elevation and then

recorded the data on the data sheets The first man meanshy

while had taken readings of the line voltage line current

and manometers and checked the turbine speed by multiple

readings During the length of the run all values were

38

checked to determine mean values for recording

The minimum length of one run was about five minutes

If one or more measure ants tended to drift during the run

all values wer discarded and a new run began as soon aa

qu111br1um was stabl1shedo

B -0-al_e_u_l_a_t--d Data

The h d on the tu~bine 1 defined by

($)

The maxtmwm velocity V4 was equal to about o8 tampet per

secon4 which makes it a negligible quantity when converted

into velocity head

An engineerbulla level was used to deterine the d1ffePshy

ence 1n elevation between the compound water-mercury manoshy

meter and the hook gauge Using this value the equation

for turbine bead becomes

where z4 is the hook gauge reading

The rate of flow 1 cent

w weight or water collected average time to collect

The inlet velocity v1 vas calculated by dividing the

weight rate or flow by the specific weight of water and the

)9

area ot ~e inlet pipe This was equivalent to dividing

the weight rate of flow by 490 Then the power input to the turbine is equal to

WHpin rri

10 (6)

Also

(P ~ut) Turbine

(P out) + Generator

(P lost) Generator

The power output of the generator is simplJ the

produot ot the terminal voltage and the armature (line)

curPent The power lost in the generator can be subdivided

into copper losses and stray power losses lo evaluate

these cunes based on losses of an identical generator

11leampsured by the Department ot Mechanical Engineering were

used The loss curves are reppoduced in part in Figures

15 and 16

Determination ot generator losses proceeds as tollowau

(1) From Figure 15 detem1ne the vo1tage drop in the

armature circuit using the temperatures of 1220 F and the

meaaured current

(2) The induced voltage is t~e sum of the terminal

voltage and the voltage drop 1n the armature circuit

() Entering the induced voltage and the turbine speed

into Figure 16 the stray power loss can be determined

(4) The copper lose can be evaluated from Figure 1$

using the measured current and the temperatlll-e of 1220 P

40

25 ~------~--------~--------~------~

U) -U) - 20

f-4 ~

-~ -gt 0

0

VOLTAGE DROP

~ - i -

- bullbullbull bull - -middot-middot -+ ~- + -t--+ ~ - ~ middotbull ~-~ middott- -+----- _ -4 middotmiddot- --~-+-t---r~~ ~--+t-t- - ---t-c-++~-ulf--

0 50 75 100

Figure 15 - Curves of Generator Voltage Drop and Copper Loss

41

1200

1000

800

600

800

0

0

~-

middot--~ 1shy --1 + bull l

100

I -

150 200

IIDOOED VOLTAGB (VOLTS)

Figure 16 - Curves of Generator Stray Power Loss

_ j

-bullshy -L---- shy middot -shy

250

- r

42

(5) The generator los os equal the sum of the eopp r

loss and stray power loss

~e efficiency or the turbine is taken as

etticiency u e =P out (8)Pin

~ample pound Determ1n1gg turbine Power Output

The following data are taken trom that ot Run 1-9-1

Line voltage 1040 volts Line current 870 amperesSpeed 355 revolutions per minute

The induced voltage 1a determined as follows

Line voltage 1040

Voltage drop 90 using Figure 15 with line current of 870 amperes and temperature ot 122 degrees)

Induced Toltage 1130 volta

The power output of the turbine is determined as follows

Generator output 90$0 (line voltage z line current)

Oopper loss 7 (using Figure 15 with line current of 870 amperes and temperatUe or 122 degrees)

Stray power lose 470 (using Figure 16 with speed ot 355 revolutions per miDUte and induced voltage or 1130 volts)

Turbine power output 9527 vatta

or turbine power output 1s 12z2 horsepower

43

The conversion of the calculated data to a constant

head is based on the conventional assumption of constant

efficiency regardless of turbine head For a constant head

ot 81 teet a purely arbitrary figure the tollowing relashy

tionships are ass1lJiled to be true

I ____L (9) (i)l72

(10)

For these two values the specific a peed may be combull

putedt

N t Jt VPt (11)8 243

Chapter VI

~RESULTS

A -Pr_e_ae_n_t_a_t_t_o~n g Reaultbull

Graphical presentation ot the results ot this te1t

are given as follows

Figure 17 -Turbine characteristics with 100~ dratt

tuba 1low area

Figure 18 - Turbine characteristics with 7S dratt

tube tlow area

Figure 19 bull Comparison ot power and etticiency at

over gate conditions between 100 and

75~ draft tube flow area

Figure 20 bull COZQparison of power and ettic1ency at

halt gate conditions between 100~ and

7S~ draft tube flow area

Figure 21 bull Comparison of power and etticiency at

over gate condition between 100~ and

So dratt tube tlow area

Figure 22 - Comparison in variation ot apec1t1c

speed between 100 and 75~ dratt tube

tlow area

50

45

20

-bull - 1--shy40

bull J-~ 30

~ ex

~ 20

~~ ~ -)q

I

~ - _

- -

10~ OF DRAFT TUBE FL(Jif AREA

CONSTANT HEAD OF 8l FEST10

POIER OUTPUT EFFICIENCY SPECIFIC SPEED

0 ~--------------_--------~------~------~ 400 600 800 1000 1200 1400

TURBINE SPEED (RPM)

Figure 17 - Turbine Char~cteristics with 100 Draft Tube Flow Area

50

46

-bulllle

~ 7 ~ OF DRAFt TUBE FLOW AREA

0 -~~-rl C05STAMT BEAD OF 81 mET 1J~

POIER OOTPUT ---+- ---o ~_H EFFICIDCY ~ I shy

bull ql SPECIFIC SPEKD - ~ -

bull ~ J 10 L rmiddotr- r- -

bullz- I

~~ 30 ~~--~----~~-

20 ~ ~ middot-shy

26

~~ 25

~0 ~r-----i (

Tbull -bullshy

400 600 800 1000 1200 1400

TURBINE SPEED (R PK )

Figure 18 -Turbine Characteristics with 75 Draft Tube Flow Area

47

EFFICIENCY 60

1-----shy

-~ 50~--~--~~-~middot middot middot middot r~-~----~~~~---4~-r~-~~gtt

II

POWER~ J ~ bull bull

u I

sH

40~------+-------+---- -~~--~~-~~~~

~----~rl 1 bull

I

I

0~--------------~------_------~--------

~ -OVER GATE CONDITION

COIJSTANT HEAD OF 81 FEET

0 o 10~ DRAFt TUBE

_-- _ 7~ DRAFT TUBamp FLON AREA II

10_~-----+--------r-------r----~~

400 600 800 1000 1200 1400

TURBINE SPEED (RPM)

Figure 19 middot - Comparison between 75 and 100 Draft Tube Flow Areas of Power and Efficiency at Over Gate Conshydition

48

t

bull --4 r ~- ~ middot~

70 1-----------+-~~~~~+middot ~ ~~ middot middot -~~--~~--------~~----~-+1

-~-

Atbull bull

lla-

60

amp0

40

20

10

oampOO

t _ - - ~-+- - -~-

l2 GATB COJIDITIOJJ

COJISTABT HJW) OF 81 JBET

o 0 lOQ( DRAFl TUB8 FLOI AREA

e-- - e 75 DRAFT TUBE FLOW AREA

800 1000

- r-

~

TURBIbull SPBIID (RPII)

Figure 20 - Comparison between 75 and 100 Draft Tube Flow Areas of Power and Efficiency at Half Gate Conshydition

49

60

50

-40

bull 30

IIQbull

20

10

0

400

- t - ~

EFFICIENCY

_J bull - bull bull

~ r r middot t -+ shy L -t -

OVER GAD COliDITIOI

CONSTABT BEAD OF 8l FBB

o o 10~ DRAFt TUBE FLOI ADA middot--- 5~ DRAF TUBE FLQPi AREA

600 800 1000 1200

Figure 21 -Comparison between 50~ and 100~ Draft Tube Flow Areas of Power and Efficiency at Ove~ Gate Conshydition

50

25

20

15

10

0

Figure 22

~- T -4 -t- -l --~-

t-~ I

middot --~- t ~---- _ __ _ + --

----~- --r-- --

~-=J-~-=-~ -==~ _ ~- -- ---f---1 - shy

CONSTANT HEAD OF 81 FEBT

o--o 1~ DRAFT TUBE FLltll AREA

75C DRMT TUBK FLCIJ AREAmiddot--middot-middot 600 800 1000

TURBINE SPEED (RPK)

Comparison of Specific Speeds for 75 and 100 Draft Tube Flow Areas

51

B Discussion 2 Result

Consideration of Figures 17 and 18 indicates the

overall eftioi ncy pattern or hill is significantly or

rounded for the 7$~ flow area than for the 100~ flow area

bia implies a greateP efficiency is possible at speeds

leas than or greater than design speed with an insert in

the draft tube However the muilDum efficiency is lemiddotas

Direct comparison at over gate conditions is made in

Figure 19 ~e same general trend is noted tor both the

etticiency and power curves for the 7$~ flow area case

The eurves show higher values at overspeed than do the

correaponding cWvea for the 100 flow area case It ia

not clear whether the curves have been shifted by the dratt

tube constriction or whether the curves simply bulge past

the normal curves at both overspeed and underspeed condishy

tions The power curves apparently peak near the aeme

point bullalthough maximum power is still obtained with the

normal draft tube area

For the comparison at halt gate operation shown in

Figure 20 a general improvement has apparently been made

by restriction of the draft tube flow area At every speed

the etticienoy and the power is greater for the restricted

tlow case The two ett1o1ency curves and two power curvea

are practically parallel throughout the speed range ot

teat

As the flou aroa i e decreased still farther a s1gn1

ticant change appears Reterr1ng to Figllle 211 tor the $0

flow area curves it a obvious that exit losses have

become excessive at the overgate condition because the

efficiency and power are everywhere leas than tor the case

of normal draf t tube area

Earlier it was pointed out t hat 1t the r esult s 1nd1bull

eated an increase in both power and ef tieiency- t hen it

could be assumed tha t the additional los s i ntroduced with

the draft tube insert is less than the diminished losses

due to leas shock losa and water passage losses For the

places where both the efficiency and power have been

increased we can assume that the insert has improved turshy

bine performance

For the places where the power haa been decreased

nothing can be said as to the elimination of ampbock loss

because the new lose present with the drat tube insert has

overshadowed any gains in eftecti Ve head upatJ-eam of the

insert

Near the peak of the efficiency hill howeve~ it may

be pointed out t hat shock loaa ie a minimum with a normal

draft tube and the insert merely adds an additional loss

with the resultant decrease in maximum efficiency tor the

7$~ flow area case

Perhaps the most s1gn1ticant set of eurves is shown aa

53

Figure 22 In this graph values of specific speed tor the

75 and 100~ flow area cases for both over gate and one

halt gate openings are plotted against turbine speed At

every speed and both gate openings the value ot specific

speed for th 75~ flow area case is greater than that for

the 100 t1ow area ease

Since the head is a constant for both situations this

may be interpreted in either of two ways trom equation

(11)

(1) For the same turbine apeed restriction of the

draft tube t1ow area resulted in greater turbine power

(2) For the same power amputput the turbine with 75~

draft tube flow area operated at a greater speed than did

the one with 100 flow area

Since the required diameter of a turbine varies

inversely with the speed the second interpretation could

be stated such that a smaller turbine could be used to

develop the same power output

Whether viewed trom the aspect of increased power

greater speed or reduced size the performance of the turshy

bine with reduced draft tube flow area is superior to that

with the nolmal flow are in the draft tube

The curve of specmiddotific speed versus turbine speed for

the so draft tube flow area case at over gate cond1t1ona

was not included in Figure 22 This curve lies below that

for the 100~ flow area c se at all speeds

In elaboration ot the second interpretation of Figure

22 attention is directed to the relative magnitudes ot

increased apee1f1c speed tor the two gate openings Assumbull

ing that the increase in specific speed implies a shift ot

the power curve to the right along the turbine speed scale

the power curve would be shifted more tor tbe halt gate

opening than tor the over gate opening

It thia trend could be extrapolated to the other gate

openings the tendency can be seen tor the line ot beat

speed to rotate toward the line of the operating speed as

illustrated in FigtU-e ) The advantage of this has already

been discussed

This particular turbine has a low specific speed tor a

reaction turbine Aa the rated value of apecitic apeed tor

reaction turbines increases the line ot beat speed departs

even more radically from the line of operating bullpeed It a

test similar to this were conducted on a reaction turbine

ot gleater specific speed it is pJobable t hat the rotation

ot the line of beat apeed would become more p~onounced

The scheme used in th1a teat had two obvious dr wbull

backs The first was the decision to leave all the wicket

gamiddottes installed tor all conditions ot the draft tube

These gates predominated in control of the tlow The

inserts added to the draft tube merely acted as auxiliary

55

contrGla

The aecond drawback was the choice or device to place

in the draft tube The reasons foll selection of this type

of device have been previously mentioned It is to be

anticipated that adaptation ot dratt tube flow control

would result 1n a better device for an actual turbine

installation Such apparatus might take the form of a

pneumatic bladder or a h7drau11oally operated variable

venturi section in the draft tube It is conceivable that

the gate as used in this test might be adapted also

Chapter VII

OONCLtJSIOfS

From the results of this test the following eonolubull

e1ona aa to the effect ot a variable draft tube flow area

on the performance or a r action turbine may be drawn

(1) The effect ot a variable draft tube tlow area 1a

generally favorable upon the operat1Gn ot a reaction turbull

bine because or the tendency tor the line or beat speed to

rotate toward the line ot operation This resulte in

better performance of the turbine at partbullloads

(2) he etf1o1ency eh111 tor the turbine beeomaa JDore

tlat at the top leading to a smaller max1JilWD effic1enc7

but e reater etticieney at other pointe of operation with

the insertion ot an auxiliary control ror the rate ot tlov

in the draft tube

(3) The power output of the turbine will increase at

over speed over gate conditione as well a at part gate

conditions with the proper amount or draft tube eonatr1cbull

tion or flow

(4) It is possible to eliminate at least partially

eddy type shock loss by tho introduction ot flow control

in the draft tube

BIBLIOGRAPBl

1 Addison Herbert A treatise on applied h-draul1cs New York Wiley 1954 724 Pbull

2 Allen o M and I A Winter middot Co111parative testa on experimental draft tubes Tranaact1ons ot the American ociety ot Civil Engineers 87t893bull970 1924

3 Barrows a E Water power engineering 3d ed ew York McGraw-Bill 1943 791 Pbull

Bovet G A Modern trenda in hydraulic turbine design4middot in Europe Tranaactions of the American Society ot Mechanical Engineera 75975bull993 1953bull

s Oreager William P and Joel D Justin Hydroelectrichandbook 2d ed New York Wiley 19$0 1151 Pbull

6 Daily Jamea w Hydraulic machinery Int Hunter Rouses Engineering hydraulics Hew York Wiley 19$0 p 8$8bull99

Daughertybull Robert L Bydraulie turbines ew Yorkbull7middot MoGrav-Hlll 1920 281 Pbull

8 Daugherty Robert L Inveat1gat1on of tne performance ot a reaction turbine ~anaactiona or the American Society ot Civil Engineers 7811270bull1304 1915

9 Davie L M Model and prototype testa Int Trend in hydraulle turbine practice symposium lranaactions ot the American Society ot Civil Engineers 1o63S3middot368 1941

lfJ Doland James J Hydro power engineering Hew Yorkbull Ronald 1954 209 Pbull

11 Gandy Theodore s and Elmer c Schacht Direct curshyrent motor and generator troubles operation and repair New York McGraw-Bill 1911 293 Pbull

12 Gibaon Arnold H Hydraulics and ita applications5th ed London Constable 1952 813 Pbull

58

13 Button s P Component loases in Kaplan turbinebull and The prediction of efficiency from model tests Probull coedings of the Institution or Mechanical Engineers168743-762 1954

14 Knapp R T~ Oavit t1on mechanics and its relation to the d sign or hydraulic equip ent Proceedings or tne Institution ot Mechanical Engineers 166150bull16) 1952

15 Langsdorf Alexander s Principles of direct curHnt mach1nee 5th ed New York r~cGrawbullH1ll 1940 746 Pbull

16 Lsrner Chester w Characteristica of modern hydraubull lie turbines Trans e~ions of the ~~erican Society ot Civil Engineers 66306-386 1910

17 Linsley Ray K Jr and Jobulleph B Franzin1 Eleshyments of hydraulic enginebullring New York McGrawshyBill 19$5 $82 Pbull

18 Mead Daniel w Hydraulic machinery llev York McGraw-Hill 1933 396 Pbull

19 ead Daniel w Water power engineering New York McGrawbullRill 191S 843 Pbull

20 Mockmore Charles A Part gate operation at water turbines Corvallis Oregon State College Department ot Civil Engineering 1933 11 numb leaves (Unpubshylshed typescript)

21 Mockmore Oharles A Flow characteristics in elbow dratt tubes Transactions of the Amez-ican Society ot Civil Engineers 103402middot464bull 1938

22 Moody L F Hydraulic machinery In c v Davis Handbook ot applied hydraulics New York McGrawshyHlll 1942 1082 Pbull

2) Ptau At-nold Hydrbullulie turbine handbook ld ed Milwaukee AllisbullOhalmers ManufactUIing Company 1948 70 Pbull

RheingalUI w J Recent developments in Francis turshybines Mechanical Engineering 74189-196 1952

25 Russell George E Hydraulica 5th ed New York Henry Holt 1942 466 Pbull

26 Safford A and E P- Hamilton American mixed tlow turbine and ita setting Tranampactions or the Amerieal Society of Civil Engineers 851237bull1)56 1922

27 bull Spannhake W1lhe1Dh Problems or modern pump and tur b1ne design Transactions of the American Society of Mechanical Engineers 56e22$-248 1934bull

28 Sutherlandraquo R A Better ethod or representing and middot tudying water turbine performance ~ansaetions ot thmiddote American Society of Mechanical Engineers 68t675bull 686 1946

29 Teats ot five models or draft tubes tor turbines Engineering News-Record Pbull 182-184 Aug 2 1923

30 White w M American hydztaulic turbines Mechanical Engineering S2t390bull39S 1930bull

31 White w M lhe hydraucGne rega1ner1 its developmentand appl1eat1ons 1n hydroelectric plants Meohanlobulll Engineering 43t37Sbull380 1921 middot

32 Winter I A Economic principlebull in designbull Int Trend in hydraulic urbin practice bull a ampoeiumTranaaot1ona ot the American Society ot Civil Engineerslo6332bull3S2 1941

33 Wiel1cenua G F Fluid mechan1ca or turbo-machineryNev York McGraw-Hill 1947 613 Pbull

APPENDICES

c

Appendix A

NOATIOB

A Angle between the absolute velocity vector and the tangent to the rwmer Subscripts 1 and 2 refel to entrance and exit ot the runner blade

B Angle between the relative 1elooity vector and the tangent to the rwmer Subscripta 1 and 2 refer to entrance and ezit or the runner blade

Angle between the tangent to the runner blade tip and the tangent to the runnel- Subscripts 1 and 2 reter to entrance and exit of the rt1rmer bladebull

Blade angle-gate opening conetant defined by equation (1)

e 09erall efficiency

g Gravitational acceleration assumed constant at 322 teet per second per second bull

H Turbine head detined by equation ($)

m Exit loss coeft1e1ent

Turbine speed expressed in revolutions per minute

Turbine speed under a constant head of 81 teet

specitic apeed of the turbine under a constant head ot 81 teet

p Power output in horsepower ot the tvbine

Power output of the turbine Ulder a constant head ot Sl teet

Pl- Pressure head at entrance to the tUlb1new

l1 Peripheral velocity ot the runneP Subacr1pta 1 and 2 refer to entrance and exit ot the JUnllampr blade

62

v Relative velocity reaulting trom the combination ot the absolute water velocity V and the runner periphshyeral velocity u Subscripts 1 and 2 refer to entrance and exit ot the runner blade

v] Relative velocity vector necessary to produce a tanbull gential entry into the runner blades

V Absolute water velocity Subscripts l and 2 refer to entrano and exit ot the runner blade

v2 Velocity head Subscripts 1 and 4 reter to the ~8 entrance to the turbine and the tail~ace wate~

w Unit weight ot water assumed constant at 624 pounda per cubic toot

V Weight rate ot flow in pounds per aeooncl

XX Velocity component ot ahook See Figule 2

Z Elevation head Subscripts 1 and 4 reter to entrance to the turbine and the taibace water surfacebull

Appendix B ORIGINAL DATA-Run

lfwnber

0-4-1 0-4-2 0-4-3 o-4-4 o-4-S o-4-6 0-4-7 0-4-8 0-4-9o-4-lo o-4-11 o-4-12 0-4-13

o-6-1 o-6-2 06-3 o-6-4o-6middotS o-6-6 o-6-7 o-6-8 0-6-9 o--6-lo o-6-11

Speed

rmiddot2middotbullmiddot(1)

336 38$ 451 S$9 620 669 6lt)$ 120 787 860 932

102imiddot109 bull

352 355 443middot 543middot 620 654AJs32

911 1001 1111

~essure Head rt (2)

410 410 416 426 431 43-7 439 44-9 452 467 482 soo $1 bull $

350 351 35middot7 )66 37-9 37-9 392 41 bull 3 43middot3 460 489

Elevation Bead

fjj $7 $7 $7 $7 $7 $7 51 57 5-15858 $8 58 56 56 $6565656 51 575As5a

Velocit Head

flj 07 07 07 06 06 06 06 os 05 os0404 03

09 09 oa o8 o8 os 07 07 06 o~o

Total Head rt ($)

47middot4 4A44 o 489 49-4 soo $02 $11 $14 $29 5imiddot45 2 576

41 bull $ 416 421 430 44middot3 44middot3 456 47-7 496 523551

Plow

lbtjec

326 324middot317 311 306 30029middot28 middotmiddot middot 386 275middot260 240 218

359 36~35 bull 349 345middot 339 330 318 300 273 240

Line Potential

vyqjbull 1060 1220 ~-0o 1920 2150 2000 2$60 2000 1940 18)015io11 o

1000 1100 139bull5 1760 1925 16$0 1620 1610 1540 1330 870

Line Current

amlscs 960 900 830 740 730655 70bull 0 530 660 600 5imiddot54 6 )60

982 930 860 780 ~3-545

79-5 74-5 670 560 370

P

Appendix B ORIGINAL DATA (Continued)

Run Number

Speed

Pbulltmiddotbullmiddot )

leasure Head ft(2

Elevation Head tt(J)

Velocity He-dfmiddotj

Total Bead tt($

Flow

lbstsec( )

Line Potential vo~ta( )

Line Current

amjs (sect

0bulllt)-1 0-9-2

3ll6 398

28o ~~1

$6 56

1o 10

346 347

390 365

1ooo 1190

aao 835

0-9-3 0-9-4 o-9-S

472 565 632

292 305 312

$6 s6 56

10 o9 o9

)$8 J7~o 37~7

381376 37o

1)6614oo 141o

820 ass ass o-9-6 0-9-7 0-9-8 o-9-9 0middot9-10

680 120 762 844 920

)24337346 366 390

56 $6 56 57 $7

09 os o8 oa 07

)89401 410 431454

367~ 357348 34o 322

1400 1J6o l36o 1310 1170

843 820 7957So 67~0

0-9-ll 0-912

1001 1100

41 bull 7 45-3

s 7 6~0

06 os 480 $18

299 268

980 65$

560 36~5

1-4-1 1-4-21-4-l1-4shy1-4-5 1-4-6 l-4-7 1 4-8 1-4-9 1-4-10 1middot4-ll 1-4bull12

354middot452 562 62q 674shy102 752 760- 863 932

1022 1100-

)82389 4014oa 416 41--7 423 428 44-2 45-7 486 49-2

51S757 51 5-7 5middot15zs sa $8 58 59

07 07 06 06 06 06 06 os o bull o 04 o J

446 45-)46middot4 471 ti7-9480 q86 491505 $19 548 55-4

)28 320 311 306 300 295 291 286 269 2582iimiddot21 bull

1080 14Lo 1550 153-5 1470 141-0 1385 1310 1310 1230 1120 855

970855 875 91-0 94~0 975 966 995 860 77-S 610 4fo

0 ~

Appendix B ORIGINAL DATA (Contirmed)-Run Speed Pressure Elevation Velocity Total Flow Line Line

Number Head Head Head had Potential Current rtjjmbull t~ bttec vyfs am~a12) ( ) ti fli 8

1-6-l $6 33$ $6 0bull9 400 364 1100 93 0 1-6-2 41 34laquo2 $6 oa 406 JS7middot iios a5s l-6-3 500 3~0 5bull6 os 356 1 1 o aos 41middot~1-6~4 35bull4 5-6 oa 41middot 352 16~0 82 0 5~1-6-5 5 bull 36_2 Sbull6 08 42bull6 349middot 161 ~ 0 86~0 1-6-6 622 366 $6 oe 43bull0 345middot 158 0 88~$ 16-A 649bull 37bull1 56 os 43-S 342middot 1570 895 1~- 386 57 07 46-0 192 ) 125A44 333middot 1-6-9 3) 404 5middot1 07 468 317 1620 675 1610 911 42-4 5-7 o6 48-7 298 168 0 61 0 1-6-11 999 451 56 os Sl ll 276 ~2-0 530 1-612 1115 485 58 04 54middot7 238 90 )3 0

1middot9-l 355 279 56 10 )45 385 1040 870 1-9-2 399 28J $6 10 )49 38$ 1140 86 5 l-9-3 ~ ao 291 56 ~0 35middot1 J8J_ JJ6o 815 1bull9-4 579 303 56 09 )68 375middot J4JO 830 l-9bullS 40- 313 )6 09 31middot8 370- 1460 82~0 1-9bull6 679 2) 56 09 3 bull8 364middot 1670 710 l-9-7 682 319 56 o9 384 ) 62 1460 79 5 l-9-8 724 33middot5 56 o8 399 3$6 bull 1480 76 -5 1-9-9 762 34middot3 $6 0 bull 8 407 )48 14910 13middotS 1-9-10 833middot )60 5middot7 os 42$ 339 144$ 686 1-9-ll 926 39middot1 5-7 07 455 318 1290 600 1-9-12 1000 41middot3 0-6 476 298 1115 510$ ~ 1middot9-13 1105 452 s o4 $14 2$6 710 )10

~

Appendix Bt ORIGDIAL J (Continued)

Run Speed Pressure Elevation Velocity Total Plow Line Line Number Head ltead Head jlamp$d P()ten~ibulll Current

r~~~m ft ft lbs~seo voltattj rgj twimiddot t 1 t2gt lt3 ou t ( rt

2-9-1 384 289 S 6 10 35 5 1400 1170 810 2-9-2 443middot 29$ $6 ltimiddot9 360 379middot 11(0 87$ 2-9-J 536 30bull 3 sc 09 )68 374middot 1)40 84 bull) 2-9-4 571 306 $6 09 3~1 372 120bull 0 955 2-9-5 623 316 S6 09 J l )6S UJSo 77$ 2bull9-6 669 327 S6 09 )92 )61 1240 905 2-9bull7 712 )39 56 os 40-3 351 12(0 86 bull0 2-9-8 ~5$~ J48 56 oa 412 348 1290 81 bull ) 2-9-9 04 )63 56 oa 42-7 339 12ltJO 76$ 2middotmiddot9-10 8$2 376 5middot1 07 440 33~- ~ o 710 2-9-11 955 394 5-1 o6 457 300 1100 506 2middot9-12 1000 421 $7 06 48middoti 295 1020 $18 2-9bull13 110~ 463 56 05 $2 267 620 3~0

oshy0

Appendix Gt CALCULATED DAgA

Turbine Run Generator Generator Turbine Turbine Efficiency Turbine Turbine Specit1c

Number OutputKWlt21

Loa~Jes KWlol

Outut K bull (H)

Input RP 12)

middot Percentlt13gt

Speed r~Jmiddot(

0ltput HP ~1

Speed r-m

( 6) middot

o-4-1 0middot4-2 0-4-3 0-4-4 0-4-5 0-4-6 O-qmiddot7o-4-8o-4-9 0-4bull10 0-4-11 o-4-12

1018 1o9a 1220 1)62J40214oa1J4oo 1357 1320 1164 997 718

046 o59 071 092 096 1071oo 134 104 100 109 107

14261sso 17)01948 2008 20322011 1999 19 09 1708 14-84 11o6

281279 27-7 276 215 273271 268 268 26h 258 24-5

soa 555 62$ 705 7)1145 742 74-6714645 51s 45-1

440 sos 585 720 195 sso sao 9$$ 985

1065 1135middot 1230

318 357 319 416 422 419412 39middot9 378 324 260 191

102 12bull4 148 191 21bull 3 22o 233 249 24924middot9 238 221

0-4middot13 418 104 699 228 306 1300 117 18)

o-6-1 982 045 1376 271 $08 496 376 124 o-6-2 o-6-3 G-6-4o-6-5 0-6-6

1023 1200 13 73 J415 139h

051 0middot66 oaa ()bull 96 088

14-39 1696 1958 2026 1986

276 27middot4 273 278 274

$20 61 8 717 7)0726

q95615745 8)5685

390 ll5middot3 sos soo 490

127 170 218 243 2$$

o-6-7 o-6-8 o-6-9o-6-lo

1288 1199 1032 7-45

o9o 094 09$ 096

1846 1733 1511 1128

274 276 271 260

67S 629559 43middot4

980 1085 1165 1245shy

436 )83316 21bull 7

266 276 270 239

0-6-11 322 1oo 566 2141 2JS 1350 101 177 0 --4

Appendix C CALCULATED DAlA ( Continued)-Run

Number Generator Generator

Out2ut Losaes xw LW- 12gt (lO)

Turbine Out2ut

ltPlJ

Turbine Inat lfP Jig)

Etpound1e1ency

PireentDl

Turbine Sed x-~m( 1

Turbine OutEut RPJl)

Turbine Specific

SeeedrIbullntbull

( 6)

o-9middot1 0-9-2 0-9-3 o-lt)-4 09-$ 0bull9-6 0-9-7 0-9-8 0-9-9 0-9-10 o-9-11 0-9-12

aao 994

111$ 1197 1206 1180 11)21081 982 784 5-49 2)9

0middot45oss o6$ 070 07$ 0-77 (l77 or~ o s06o 8 096

123~ 1402 1$80 1698 17bulllS 168$ 16bull18 ~middot5430 1151 a~J4 9

24middotgt24middot3248 25~25 260 260 259 267 266 26middot1 2S2

sos 577 63-7 671 676 650 621 60036J4

327 178

$) 610AlO 3$

92S 980

102$ 1070 1157middot 1230 1300 137Smiddot

44middot4 soo 523 ssomiddot 540so6 46-5 432 368 274 18~8

J46 176 21-1 255 2802s_A 28 289 288 265 231 168

1-4-1 1-4middot2 1-4-3 1-4-4 1-4-5 1-4-6 1-4-7 1-J-8 1-4~9 1-4-10 1-4-11 1-4-12

10bull48 1231 13-S6 1397 1)821375 1))8 1303 1127 953 683) 51

048 067 o7A07 0 bull79 oa1 oss o bullao osa 0lt)0 096 099

J468 1740 1921 1978 1958 19$1 1911 lSSi162 1)98 1045

603

266 264 262 262 261 2512$7 2$6 24middot7 24-3 233 217

551 660 13middot3155 75-6 7~-97 middot4 72$ 67 51middotJ 44middot9 21middot1

475 605 A4220

875middot 910 970_

1000 1090bull 1166 1243 1330

5816

44middot444middot5 430 427 412 392 329 273 188 l0-7

117 101 204 22$ 2)7245 2562sa 257251 222 179

a-C))

Appendix Ct CALCULATED -DATA ( Ocntinued)

1-6middot1 1023 o$2 14-41 26S 505 41~6 26~

54middot5 13middot3l-6-2 1201 067 1boo 625 47-9 17shy~middot41-6bull3 1296 oA9 1 middot43 26 9 700 so5 20bull 4 l-6-4 l3j5 o 0 19~09 268 71bull3 A5o 514 222 1-6-5 1) 5 o81 19(gt4 271 725 51-5 238 l-66 1398 081 198) 27-0 736 8 S13 252~-middot l-6j 1405 083 199i 211 733 885 $middot06 2$9 l-6 13middot9~ 103 2amp 0 279 71 8 985~ 467 ~-69 1228 1 bull 02 17-SS 270 661 109$ 407 ~3~ l-6bull10 1025 100 lSll 26i 573 1175middot 27~S32middot~l-ampu 153 1-00 llft3 26 444 1270 22 24bull8 1bull6-12 294 100 52a 231 22 3 1360 95 172

1-9bull1 904 048 1275 2J4Z $28 S4$ 459 1$2 1-92 98$ oss 13-92 24middot4 57-0 6JO 49bull1 176 1-9middot3 1110 066 1$76 24middot9 63middot4 I2o 536 21-7 l--9-4 1187 072 1685 251 66$ 5 $$ bull 0 261 1middot9-5 llltJ7 1710 25middot4 67-3 93$ 536 28~20-671middot9-6 1186 o 8 1708 25-7 67) 980 $15 2691-9- 1161 oBo 1660 2$middot3 6$6 990 508 29-1 l~- ll-32 oB) 16sect0 2$8 632 1030 471 291 1-9bull9 109$ oa5 2$7 614 1075 29S~middot 0 4imiddot41-9-10 9~91 oas 262 S$1 1150~ 3 o 292 1-9-11 o9o u57 12JiO 21gt 26-77middot74

-45 26sect ~middot91-912 $69 091 sas 25 middot3 1)0$ 196 2J-8 1-9-1) 220 098 426 2)9 178 1390middot 84 16 6

0 0

Appendx C CALCULATED DATA (Continued)

Turbine Run Generator Generator lurbine Turbine Eft1e1eney Turbine lurbine Spee1f1c

Number Output Losses Outit Input Speed Output SPed middot k_-V KW R _ H_bull_P Percent r Thm HP rpm_ (9) tlo) 11) middot (12 _) (lJI ( ) (1$ (14)

2-9-1 9--46 055 1)62 258 528 580 164 2-9-2 1024 056 248 58 4 665 4 9 191iimiddot48 4~middot0 2-9-3 1132 067 05 2$0 641 795 52q 237 2-9-4 1148 065 1027 2$1 -~8 845 525 252 2-9-5 11 77 oso 16-83 253 6 910~ 522 270 2-9 6 1122 071 1600 251 622 960 47-5 2722-9-A 1092 015 1562 257 608 1010 445 2z12bull9- 1052 079 1514 261 580 1060 41middot7 2 2 2middot9-9 986 o82 ]429 26) 542 1105 372 277 2-9-10 915 086 1340 268 500 1160 334 27-6 2-9-11 638 087 972 254 )81 1270~ 229 250 2-9-12 )28 090 828 259 )19 1295 179 226 2-9-13 192 094 383 2$ 6 150 1370 7 3 152

-3 0

Page 32: The Effect of A Variable Draft Tube Flow Area on the

and 149 amperes lbe generator ti ld was aepar tely

excited using direct current from a motor g n r tor ampt

(l$ p 4~8)

The power output of the generator waa dissipated in

the water rheostat (3 p 488-489) shown in Figures 9 and

10 The galvanized tank contain d water ot variable d pth

on an electrode ot cast iron m aauring 1bull x 1 x 1

In the initial installation of the turbine it was

intended that the power output should be measured with a

Prony brak bull For th purpoa68 or this teat it was decided

that the brake was too instable and the generator was

substituted The platform for raising the generator the

nee asary two teet for alignment was built out of available

material In this case heavy laminated wood blocks reiashy

torced with other timbers were used and bolted through the

concrete deck (11 Pbull 36-$7)

Due to the light concrete deck the lack ot mas in

the platform and the slight misalignment in the flexible

coupling ao e vibration waa encountered It seemed to

ncr aae linearly to a maximum at the speed of bout 750

revolutions per minute Above this speed no vibPation was

noticeable The vibration waa not se~ere and does not

appear to have materially affected the test results

26

B Intrumentat1on ~ eaeur1ng Devices

The pressure head at inlet to the turbine vaa meaave4

bymeane ot two )6 inch waterbullmeroury manometerbull connected

in series as shown in Figure 8

The terminal voltage ot the generator vas meaeured by

a laboratory voltDleter with a range to )00 yolta and callbull

brated to within 15 Yolta

The armature current bull and hence the line current was

measured by a laboratory ammeter with a range to 150 amperea

and callbrated to w1 thin o 7S amperes

Tae rate ot tlow was established by weight and time

meaeurementa The weighing ank has a capacity ot 121 000

poundsJ the weight belng indicated by Toledo direct reading

scales Timing was done with a hand atop watch with clivibull

aion ot 02 second

he ~ater level in the tailrace was dete~1ned by a

hook gauge lhie was read to the nearest 001 toot

The turbine and generator speeds were eaaured by a

hand tachometer The technique of almost cont1nuoua readbull

ings of the speed gave an error ot no more than 5 revolubull

tiona per minute

c Operational Procedure

Atter the water level in the aump was checked to

insure an adequate auppl7 the puapa were primed and

27

Figure 7 - Test Generator and Plattorm

Figure middot8- Instrument Board and Field Rheostat

28

started After venting they were valved for operation 1n

parallel

The motor generator set was started to supply the

field current and the circuit breaker was closed Water

wa added to the water rheostat to the level shown in

Figure 10 ~ field current wae minimized by cutting in

all the f ield resistance in the field rheostat of Figure 8

The l2 inch gate valve shown in Figures 5 and 6 waa

slowly opened and the turbine and generator brought up to

speed The 12 inch gat valve and turbine were vented and

the pumps were checked to insure neither had lost ita prime

lhe water rheostat offers very steady load 1f the

water level is essentially constant and the water temperabull

ture 1a fixed () p 488~89) In order to maintain this

constant temperature it was decided not to circulate the

water in the rheostat but rather to allow the water to

boil thua achieving the desired result A standing wave

was set up on the face ot the electrode by the boiling

action but a atable load was eatablished except at very

low water leYels where th11 agitation led to fluctuationa

in the line current

After putting the turbine and generator on the line

maximum power was dissipated in the rheostat by redueing

the turbine speed to between oSO and Soo revolutions per

minute Salt vas added to the rheoetat wat r to increasemiddot

29

Figure 9 - View of Water Rheostat

Figure 10 - View of Water Rheostat

Separate Field ExcitationFrom Motor-Generator set Compound Water-Mercury

---shy

re Manometer

I Q)

~ 0

~

Book Gauge

Open Channel

I

Slap Reservoir

Figure 11 - Wat~r Flow Diagram and Electrical Layout

31

waiting pe~iod ot perhaps an h~ followed

while the boiling point or the water wbulls reacbe4 During

this ti+ne the manometer was vented end eheoked electrical

measur1ng 1nstlUments were connected end the hook gauge was

adjusted tor elevation

It required about two- houtte tor the generator to reach

its normal operating tempe-ratu~e_ After the water in the

rheostat and generator had reached their operating temperabull

turea it was possible to begin the taking of data

The only vaPiable which was controlled wee the turbineshy

generator speed However the upper l1ut1t of safe line

current was slightly over 100 ampJilPampPes and the eireuit

breaker would open when the current reached lOS ~ere bull

Control was exercised by means ot regulating the water

level and salt 1n the water rheo tat and the res1stsnoe of

the tield rheost t~

The etfeet ot each type ot regulation on the three

variables is shown below

Volta Aaperebull Speed

Inc Dec Inc Dee~ Inc Dec

Wa~e1 Level Inc Dec~ X

X X X X

X

Salt Concentration

Inc Dec X

X X X X

X

field Resistance

Inc Dec

X X

X X

X X

32

Jlot all methods gave the ame amount ot change in a

given variable and a period of experiment and trial led to

the following scheme starting the rune with the lowest

turbine speed the water level was high with a high amount

ot salt and the field resistance was cut completely out

Aa it became necessary to increase the speed tor each

aucceasive run either cutting in t he field resistance

decreasing the salt concentration or lowering the Vater

level would produce the desired result However decreasbull

1ng the salt concentration had to be done Without a net

gain in water which led to a tluahing procedure that was

not particularly good because cold water was introduced

which required time to heat to the boiling point Cutting

1n additional field resistance was a good method but th1a

increased the amperage possibly to the point of opening

the circuit breaker Lowering the water level was aatiashy

factol1 until the level got too low causing the current

fluctuation previously mentioned Actually it turned out

that a combination of lowering the water level and cutting

field resistance in would carry the speed from ita minimum

to 1ts maximum value it the proper choice were made each

time the speed waa to be changed At the conclusion of

each aet of runs at a high speed the water level would be

low and the field resistance high

33

TURBINE

PAD AND DECK

TAILRACE

WATER SURFACamp

CONCRETE

DRAFT TU1B INSERTS

7 5( DRAFr TUBE

FLltJI ARIA

5~ DRAFT TUBE

FLOI ARSA

Figure 12 - Sketch of Draft Tube and Test Inserts

34

Figure 13 - View of Draft Tube Insert

Figure 14 - View of Draft Tube Insert

D c __ ~s_middot hedu_le of

A number was assigned to each run The fi~st number

applies to the draft tube tlow areas

1 bull 100~ flow area or 0~ oonatriction

2 - 7S tlow area or 2$ conatr1ct1on

3 SoC flow area or so~ constriction

The second number refers to the wicket gate openings

9 over gate opening

6 bull intermediate gate opening

4 bull one h lt gate opening

The third number 14entif1ea the location of the particular

1Wl in a set ot rona made at a given dratt tube tlow area

and wicket gate opening

fnua run number 1bull4bull10 would identity this as the

tenth run ot a set made at halt gate with 75 ot the draft

tube t1ow area

Rune w re made tor a g1yen dratt tube condition

Firat tor tull 41-aft tube flow area seta ot rune were

made for the overgate halt gate and intermediate gate

conditione An insert was placed in t he draft tube and

rune based on the same gate conditions were made tor the

7S~ draft tube flow area case The insert was then changed

to allow only $~ draft tube flow area

The inserts are sketched 1n Figure 12 and photographed

ln Flgurea 13 and 14 They oonaisted of circula~ segments

36

or l2 ineh plywood mount 4 on wooden legs 10 inches high

The 1nse7te were placed in position and secured by th use

ot a-clamps on the legs and the outside ot the bottom of

the draft tube The obvious disadvantage to this method

waa the neoeasity tor draining the water from the tailrace

tor a change ot 1naert The advantage vas of course the

simplicity ot design and construction

Chapter V

DATA-A Original Data

The normal data-taking crew consisted or two men

Assuming adjustments having been made to secure a certain

turbine speed (aee section on Operational Procedure) one

man would take semi-continuous speed readings with the hand

tachometer until a state or rotational equilibrium was

reached This could be only a period or two minutes up to

ten or tifteen minutes As soon as steady speed was

assured the data taking would begin The second man went

to the weighing tank Where a minimum ot three weighingamp

were made The requirement was to get three consecutive

readings such that the ditterence between tbe smallest and

largest time did not exceed 04 seconds The time to

collect a given weight ot water was then assumed to be the

arithmetic average of the three times He then went to the

hook gauge determined the hook elevation and then

recorded the data on the data sheets The first man meanshy

while had taken readings of the line voltage line current

and manometers and checked the turbine speed by multiple

readings During the length of the run all values were

38

checked to determine mean values for recording

The minimum length of one run was about five minutes

If one or more measure ants tended to drift during the run

all values wer discarded and a new run began as soon aa

qu111br1um was stabl1shedo

B -0-al_e_u_l_a_t--d Data

The h d on the tu~bine 1 defined by

($)

The maxtmwm velocity V4 was equal to about o8 tampet per

secon4 which makes it a negligible quantity when converted

into velocity head

An engineerbulla level was used to deterine the d1ffePshy

ence 1n elevation between the compound water-mercury manoshy

meter and the hook gauge Using this value the equation

for turbine bead becomes

where z4 is the hook gauge reading

The rate of flow 1 cent

w weight or water collected average time to collect

The inlet velocity v1 vas calculated by dividing the

weight rate or flow by the specific weight of water and the

)9

area ot ~e inlet pipe This was equivalent to dividing

the weight rate of flow by 490 Then the power input to the turbine is equal to

WHpin rri

10 (6)

Also

(P ~ut) Turbine

(P out) + Generator

(P lost) Generator

The power output of the generator is simplJ the

produot ot the terminal voltage and the armature (line)

curPent The power lost in the generator can be subdivided

into copper losses and stray power losses lo evaluate

these cunes based on losses of an identical generator

11leampsured by the Department ot Mechanical Engineering were

used The loss curves are reppoduced in part in Figures

15 and 16

Determination ot generator losses proceeds as tollowau

(1) From Figure 15 detem1ne the vo1tage drop in the

armature circuit using the temperatures of 1220 F and the

meaaured current

(2) The induced voltage is t~e sum of the terminal

voltage and the voltage drop 1n the armature circuit

() Entering the induced voltage and the turbine speed

into Figure 16 the stray power loss can be determined

(4) The copper lose can be evaluated from Figure 1$

using the measured current and the temperatlll-e of 1220 P

40

25 ~------~--------~--------~------~

U) -U) - 20

f-4 ~

-~ -gt 0

0

VOLTAGE DROP

~ - i -

- bullbullbull bull - -middot-middot -+ ~- + -t--+ ~ - ~ middotbull ~-~ middott- -+----- _ -4 middotmiddot- --~-+-t---r~~ ~--+t-t- - ---t-c-++~-ulf--

0 50 75 100

Figure 15 - Curves of Generator Voltage Drop and Copper Loss

41

1200

1000

800

600

800

0

0

~-

middot--~ 1shy --1 + bull l

100

I -

150 200

IIDOOED VOLTAGB (VOLTS)

Figure 16 - Curves of Generator Stray Power Loss

_ j

-bullshy -L---- shy middot -shy

250

- r

42

(5) The generator los os equal the sum of the eopp r

loss and stray power loss

~e efficiency or the turbine is taken as

etticiency u e =P out (8)Pin

~ample pound Determ1n1gg turbine Power Output

The following data are taken trom that ot Run 1-9-1

Line voltage 1040 volts Line current 870 amperesSpeed 355 revolutions per minute

The induced voltage 1a determined as follows

Line voltage 1040

Voltage drop 90 using Figure 15 with line current of 870 amperes and temperature ot 122 degrees)

Induced Toltage 1130 volta

The power output of the turbine is determined as follows

Generator output 90$0 (line voltage z line current)

Oopper loss 7 (using Figure 15 with line current of 870 amperes and temperatUe or 122 degrees)

Stray power lose 470 (using Figure 16 with speed ot 355 revolutions per miDUte and induced voltage or 1130 volts)

Turbine power output 9527 vatta

or turbine power output 1s 12z2 horsepower

43

The conversion of the calculated data to a constant

head is based on the conventional assumption of constant

efficiency regardless of turbine head For a constant head

ot 81 teet a purely arbitrary figure the tollowing relashy

tionships are ass1lJiled to be true

I ____L (9) (i)l72

(10)

For these two values the specific a peed may be combull

putedt

N t Jt VPt (11)8 243

Chapter VI

~RESULTS

A -Pr_e_ae_n_t_a_t_t_o~n g Reaultbull

Graphical presentation ot the results ot this te1t

are given as follows

Figure 17 -Turbine characteristics with 100~ dratt

tuba 1low area

Figure 18 - Turbine characteristics with 7S dratt

tube tlow area

Figure 19 bull Comparison ot power and etticiency at

over gate conditions between 100 and

75~ draft tube flow area

Figure 20 bull COZQparison of power and ettic1ency at

halt gate conditions between 100~ and

7S~ draft tube flow area

Figure 21 bull Comparison of power and etticiency at

over gate condition between 100~ and

So dratt tube tlow area

Figure 22 - Comparison in variation ot apec1t1c

speed between 100 and 75~ dratt tube

tlow area

50

45

20

-bull - 1--shy40

bull J-~ 30

~ ex

~ 20

~~ ~ -)q

I

~ - _

- -

10~ OF DRAFT TUBE FL(Jif AREA

CONSTANT HEAD OF 8l FEST10

POIER OUTPUT EFFICIENCY SPECIFIC SPEED

0 ~--------------_--------~------~------~ 400 600 800 1000 1200 1400

TURBINE SPEED (RPM)

Figure 17 - Turbine Char~cteristics with 100 Draft Tube Flow Area

50

46

-bulllle

~ 7 ~ OF DRAFt TUBE FLOW AREA

0 -~~-rl C05STAMT BEAD OF 81 mET 1J~

POIER OOTPUT ---+- ---o ~_H EFFICIDCY ~ I shy

bull ql SPECIFIC SPEKD - ~ -

bull ~ J 10 L rmiddotr- r- -

bullz- I

~~ 30 ~~--~----~~-

20 ~ ~ middot-shy

26

~~ 25

~0 ~r-----i (

Tbull -bullshy

400 600 800 1000 1200 1400

TURBINE SPEED (R PK )

Figure 18 -Turbine Characteristics with 75 Draft Tube Flow Area

47

EFFICIENCY 60

1-----shy

-~ 50~--~--~~-~middot middot middot middot r~-~----~~~~---4~-r~-~~gtt

II

POWER~ J ~ bull bull

u I

sH

40~------+-------+---- -~~--~~-~~~~

~----~rl 1 bull

I

I

0~--------------~------_------~--------

~ -OVER GATE CONDITION

COIJSTANT HEAD OF 81 FEET

0 o 10~ DRAFt TUBE

_-- _ 7~ DRAFT TUBamp FLON AREA II

10_~-----+--------r-------r----~~

400 600 800 1000 1200 1400

TURBINE SPEED (RPM)

Figure 19 middot - Comparison between 75 and 100 Draft Tube Flow Areas of Power and Efficiency at Over Gate Conshydition

48

t

bull --4 r ~- ~ middot~

70 1-----------+-~~~~~+middot ~ ~~ middot middot -~~--~~--------~~----~-+1

-~-

Atbull bull

lla-

60

amp0

40

20

10

oampOO

t _ - - ~-+- - -~-

l2 GATB COJIDITIOJJ

COJISTABT HJW) OF 81 JBET

o 0 lOQ( DRAFl TUB8 FLOI AREA

e-- - e 75 DRAFT TUBE FLOW AREA

800 1000

- r-

~

TURBIbull SPBIID (RPII)

Figure 20 - Comparison between 75 and 100 Draft Tube Flow Areas of Power and Efficiency at Half Gate Conshydition

49

60

50

-40

bull 30

IIQbull

20

10

0

400

- t - ~

EFFICIENCY

_J bull - bull bull

~ r r middot t -+ shy L -t -

OVER GAD COliDITIOI

CONSTABT BEAD OF 8l FBB

o o 10~ DRAFt TUBE FLOI ADA middot--- 5~ DRAF TUBE FLQPi AREA

600 800 1000 1200

Figure 21 -Comparison between 50~ and 100~ Draft Tube Flow Areas of Power and Efficiency at Ove~ Gate Conshydition

50

25

20

15

10

0

Figure 22

~- T -4 -t- -l --~-

t-~ I

middot --~- t ~---- _ __ _ + --

----~- --r-- --

~-=J-~-=-~ -==~ _ ~- -- ---f---1 - shy

CONSTANT HEAD OF 81 FEBT

o--o 1~ DRAFT TUBE FLltll AREA

75C DRMT TUBK FLCIJ AREAmiddot--middot-middot 600 800 1000

TURBINE SPEED (RPK)

Comparison of Specific Speeds for 75 and 100 Draft Tube Flow Areas

51

B Discussion 2 Result

Consideration of Figures 17 and 18 indicates the

overall eftioi ncy pattern or hill is significantly or

rounded for the 7$~ flow area than for the 100~ flow area

bia implies a greateP efficiency is possible at speeds

leas than or greater than design speed with an insert in

the draft tube However the muilDum efficiency is lemiddotas

Direct comparison at over gate conditions is made in

Figure 19 ~e same general trend is noted tor both the

etticiency and power curves for the 7$~ flow area case

The eurves show higher values at overspeed than do the

correaponding cWvea for the 100 flow area case It ia

not clear whether the curves have been shifted by the dratt

tube constriction or whether the curves simply bulge past

the normal curves at both overspeed and underspeed condishy

tions The power curves apparently peak near the aeme

point bullalthough maximum power is still obtained with the

normal draft tube area

For the comparison at halt gate operation shown in

Figure 20 a general improvement has apparently been made

by restriction of the draft tube flow area At every speed

the etticienoy and the power is greater for the restricted

tlow case The two ett1o1ency curves and two power curvea

are practically parallel throughout the speed range ot

teat

As the flou aroa i e decreased still farther a s1gn1

ticant change appears Reterr1ng to Figllle 211 tor the $0

flow area curves it a obvious that exit losses have

become excessive at the overgate condition because the

efficiency and power are everywhere leas than tor the case

of normal draf t tube area

Earlier it was pointed out t hat 1t the r esult s 1nd1bull

eated an increase in both power and ef tieiency- t hen it

could be assumed tha t the additional los s i ntroduced with

the draft tube insert is less than the diminished losses

due to leas shock losa and water passage losses For the

places where both the efficiency and power have been

increased we can assume that the insert has improved turshy

bine performance

For the places where the power haa been decreased

nothing can be said as to the elimination of ampbock loss

because the new lose present with the drat tube insert has

overshadowed any gains in eftecti Ve head upatJ-eam of the

insert

Near the peak of the efficiency hill howeve~ it may

be pointed out t hat shock loaa ie a minimum with a normal

draft tube and the insert merely adds an additional loss

with the resultant decrease in maximum efficiency tor the

7$~ flow area case

Perhaps the most s1gn1ticant set of eurves is shown aa

53

Figure 22 In this graph values of specific speed tor the

75 and 100~ flow area cases for both over gate and one

halt gate openings are plotted against turbine speed At

every speed and both gate openings the value ot specific

speed for th 75~ flow area case is greater than that for

the 100 t1ow area ease

Since the head is a constant for both situations this

may be interpreted in either of two ways trom equation

(11)

(1) For the same turbine apeed restriction of the

draft tube t1ow area resulted in greater turbine power

(2) For the same power amputput the turbine with 75~

draft tube flow area operated at a greater speed than did

the one with 100 flow area

Since the required diameter of a turbine varies

inversely with the speed the second interpretation could

be stated such that a smaller turbine could be used to

develop the same power output

Whether viewed trom the aspect of increased power

greater speed or reduced size the performance of the turshy

bine with reduced draft tube flow area is superior to that

with the nolmal flow are in the draft tube

The curve of specmiddotific speed versus turbine speed for

the so draft tube flow area case at over gate cond1t1ona

was not included in Figure 22 This curve lies below that

for the 100~ flow area c se at all speeds

In elaboration ot the second interpretation of Figure

22 attention is directed to the relative magnitudes ot

increased apee1f1c speed tor the two gate openings Assumbull

ing that the increase in specific speed implies a shift ot

the power curve to the right along the turbine speed scale

the power curve would be shifted more tor tbe halt gate

opening than tor the over gate opening

It thia trend could be extrapolated to the other gate

openings the tendency can be seen tor the line ot beat

speed to rotate toward the line of the operating speed as

illustrated in FigtU-e ) The advantage of this has already

been discussed

This particular turbine has a low specific speed tor a

reaction turbine Aa the rated value of apecitic apeed tor

reaction turbines increases the line ot beat speed departs

even more radically from the line of operating bullpeed It a

test similar to this were conducted on a reaction turbine

ot gleater specific speed it is pJobable t hat the rotation

ot the line of beat apeed would become more p~onounced

The scheme used in th1a teat had two obvious dr wbull

backs The first was the decision to leave all the wicket

gamiddottes installed tor all conditions ot the draft tube

These gates predominated in control of the tlow The

inserts added to the draft tube merely acted as auxiliary

55

contrGla

The aecond drawback was the choice or device to place

in the draft tube The reasons foll selection of this type

of device have been previously mentioned It is to be

anticipated that adaptation ot dratt tube flow control

would result 1n a better device for an actual turbine

installation Such apparatus might take the form of a

pneumatic bladder or a h7drau11oally operated variable

venturi section in the draft tube It is conceivable that

the gate as used in this test might be adapted also

Chapter VII

OONCLtJSIOfS

From the results of this test the following eonolubull

e1ona aa to the effect ot a variable draft tube flow area

on the performance or a r action turbine may be drawn

(1) The effect ot a variable draft tube tlow area 1a

generally favorable upon the operat1Gn ot a reaction turbull

bine because or the tendency tor the line or beat speed to

rotate toward the line ot operation This resulte in

better performance of the turbine at partbullloads

(2) he etf1o1ency eh111 tor the turbine beeomaa JDore

tlat at the top leading to a smaller max1JilWD effic1enc7

but e reater etticieney at other pointe of operation with

the insertion ot an auxiliary control ror the rate ot tlov

in the draft tube

(3) The power output of the turbine will increase at

over speed over gate conditione as well a at part gate

conditions with the proper amount or draft tube eonatr1cbull

tion or flow

(4) It is possible to eliminate at least partially

eddy type shock loss by tho introduction ot flow control

in the draft tube

BIBLIOGRAPBl

1 Addison Herbert A treatise on applied h-draul1cs New York Wiley 1954 724 Pbull

2 Allen o M and I A Winter middot Co111parative testa on experimental draft tubes Tranaact1ons ot the American ociety ot Civil Engineers 87t893bull970 1924

3 Barrows a E Water power engineering 3d ed ew York McGraw-Bill 1943 791 Pbull

Bovet G A Modern trenda in hydraulic turbine design4middot in Europe Tranaactions of the American Society ot Mechanical Engineera 75975bull993 1953bull

s Oreager William P and Joel D Justin Hydroelectrichandbook 2d ed New York Wiley 19$0 1151 Pbull

6 Daily Jamea w Hydraulic machinery Int Hunter Rouses Engineering hydraulics Hew York Wiley 19$0 p 8$8bull99

Daughertybull Robert L Bydraulie turbines ew Yorkbull7middot MoGrav-Hlll 1920 281 Pbull

8 Daugherty Robert L Inveat1gat1on of tne performance ot a reaction turbine ~anaactiona or the American Society ot Civil Engineers 7811270bull1304 1915

9 Davie L M Model and prototype testa Int Trend in hydraulle turbine practice symposium lranaactions ot the American Society ot Civil Engineers 1o63S3middot368 1941

lfJ Doland James J Hydro power engineering Hew Yorkbull Ronald 1954 209 Pbull

11 Gandy Theodore s and Elmer c Schacht Direct curshyrent motor and generator troubles operation and repair New York McGraw-Bill 1911 293 Pbull

12 Gibaon Arnold H Hydraulics and ita applications5th ed London Constable 1952 813 Pbull

58

13 Button s P Component loases in Kaplan turbinebull and The prediction of efficiency from model tests Probull coedings of the Institution or Mechanical Engineers168743-762 1954

14 Knapp R T~ Oavit t1on mechanics and its relation to the d sign or hydraulic equip ent Proceedings or tne Institution ot Mechanical Engineers 166150bull16) 1952

15 Langsdorf Alexander s Principles of direct curHnt mach1nee 5th ed New York r~cGrawbullH1ll 1940 746 Pbull

16 Lsrner Chester w Characteristica of modern hydraubull lie turbines Trans e~ions of the ~~erican Society ot Civil Engineers 66306-386 1910

17 Linsley Ray K Jr and Jobulleph B Franzin1 Eleshyments of hydraulic enginebullring New York McGrawshyBill 19$5 $82 Pbull

18 Mead Daniel w Hydraulic machinery llev York McGraw-Hill 1933 396 Pbull

19 ead Daniel w Water power engineering New York McGrawbullRill 191S 843 Pbull

20 Mockmore Charles A Part gate operation at water turbines Corvallis Oregon State College Department ot Civil Engineering 1933 11 numb leaves (Unpubshylshed typescript)

21 Mockmore Oharles A Flow characteristics in elbow dratt tubes Transactions of the Amez-ican Society ot Civil Engineers 103402middot464bull 1938

22 Moody L F Hydraulic machinery In c v Davis Handbook ot applied hydraulics New York McGrawshyHlll 1942 1082 Pbull

2) Ptau At-nold Hydrbullulie turbine handbook ld ed Milwaukee AllisbullOhalmers ManufactUIing Company 1948 70 Pbull

RheingalUI w J Recent developments in Francis turshybines Mechanical Engineering 74189-196 1952

25 Russell George E Hydraulica 5th ed New York Henry Holt 1942 466 Pbull

26 Safford A and E P- Hamilton American mixed tlow turbine and ita setting Tranampactions or the Amerieal Society of Civil Engineers 851237bull1)56 1922

27 bull Spannhake W1lhe1Dh Problems or modern pump and tur b1ne design Transactions of the American Society of Mechanical Engineers 56e22$-248 1934bull

28 Sutherlandraquo R A Better ethod or representing and middot tudying water turbine performance ~ansaetions ot thmiddote American Society of Mechanical Engineers 68t675bull 686 1946

29 Teats ot five models or draft tubes tor turbines Engineering News-Record Pbull 182-184 Aug 2 1923

30 White w M American hydztaulic turbines Mechanical Engineering S2t390bull39S 1930bull

31 White w M lhe hydraucGne rega1ner1 its developmentand appl1eat1ons 1n hydroelectric plants Meohanlobulll Engineering 43t37Sbull380 1921 middot

32 Winter I A Economic principlebull in designbull Int Trend in hydraulic urbin practice bull a ampoeiumTranaaot1ona ot the American Society ot Civil Engineerslo6332bull3S2 1941

33 Wiel1cenua G F Fluid mechan1ca or turbo-machineryNev York McGraw-Hill 1947 613 Pbull

APPENDICES

c

Appendix A

NOATIOB

A Angle between the absolute velocity vector and the tangent to the rwmer Subscripts 1 and 2 refel to entrance and exit ot the runner blade

B Angle between the relative 1elooity vector and the tangent to the rwmer Subscripta 1 and 2 refer to entrance and ezit or the runner blade

Angle between the tangent to the runner blade tip and the tangent to the runnel- Subscripts 1 and 2 reter to entrance and exit of the rt1rmer bladebull

Blade angle-gate opening conetant defined by equation (1)

e 09erall efficiency

g Gravitational acceleration assumed constant at 322 teet per second per second bull

H Turbine head detined by equation ($)

m Exit loss coeft1e1ent

Turbine speed expressed in revolutions per minute

Turbine speed under a constant head of 81 teet

specitic apeed of the turbine under a constant head ot 81 teet

p Power output in horsepower ot the tvbine

Power output of the turbine Ulder a constant head ot Sl teet

Pl- Pressure head at entrance to the tUlb1new

l1 Peripheral velocity ot the runneP Subacr1pta 1 and 2 refer to entrance and exit ot the JUnllampr blade

62

v Relative velocity reaulting trom the combination ot the absolute water velocity V and the runner periphshyeral velocity u Subscripts 1 and 2 refer to entrance and exit ot the runner blade

v] Relative velocity vector necessary to produce a tanbull gential entry into the runner blades

V Absolute water velocity Subscripts l and 2 refer to entrano and exit ot the runner blade

v2 Velocity head Subscripts 1 and 4 reter to the ~8 entrance to the turbine and the tail~ace wate~

w Unit weight ot water assumed constant at 624 pounda per cubic toot

V Weight rate ot flow in pounds per aeooncl

XX Velocity component ot ahook See Figule 2

Z Elevation head Subscripts 1 and 4 reter to entrance to the turbine and the taibace water surfacebull

Appendix B ORIGINAL DATA-Run

lfwnber

0-4-1 0-4-2 0-4-3 o-4-4 o-4-S o-4-6 0-4-7 0-4-8 0-4-9o-4-lo o-4-11 o-4-12 0-4-13

o-6-1 o-6-2 06-3 o-6-4o-6middotS o-6-6 o-6-7 o-6-8 0-6-9 o--6-lo o-6-11

Speed

rmiddot2middotbullmiddot(1)

336 38$ 451 S$9 620 669 6lt)$ 120 787 860 932

102imiddot109 bull

352 355 443middot 543middot 620 654AJs32

911 1001 1111

~essure Head rt (2)

410 410 416 426 431 43-7 439 44-9 452 467 482 soo $1 bull $

350 351 35middot7 )66 37-9 37-9 392 41 bull 3 43middot3 460 489

Elevation Bead

fjj $7 $7 $7 $7 $7 $7 51 57 5-15858 $8 58 56 56 $6565656 51 575As5a

Velocit Head

flj 07 07 07 06 06 06 06 os 05 os0404 03

09 09 oa o8 o8 os 07 07 06 o~o

Total Head rt ($)

47middot4 4A44 o 489 49-4 soo $02 $11 $14 $29 5imiddot45 2 576

41 bull $ 416 421 430 44middot3 44middot3 456 47-7 496 523551

Plow

lbtjec

326 324middot317 311 306 30029middot28 middotmiddot middot 386 275middot260 240 218

359 36~35 bull 349 345middot 339 330 318 300 273 240

Line Potential

vyqjbull 1060 1220 ~-0o 1920 2150 2000 2$60 2000 1940 18)015io11 o

1000 1100 139bull5 1760 1925 16$0 1620 1610 1540 1330 870

Line Current

amlscs 960 900 830 740 730655 70bull 0 530 660 600 5imiddot54 6 )60

982 930 860 780 ~3-545

79-5 74-5 670 560 370

P

Appendix B ORIGINAL DATA (Continued)

Run Number

Speed

Pbulltmiddotbullmiddot )

leasure Head ft(2

Elevation Head tt(J)

Velocity He-dfmiddotj

Total Bead tt($

Flow

lbstsec( )

Line Potential vo~ta( )

Line Current

amjs (sect

0bulllt)-1 0-9-2

3ll6 398

28o ~~1

$6 56

1o 10

346 347

390 365

1ooo 1190

aao 835

0-9-3 0-9-4 o-9-S

472 565 632

292 305 312

$6 s6 56

10 o9 o9

)$8 J7~o 37~7

381376 37o

1)6614oo 141o

820 ass ass o-9-6 0-9-7 0-9-8 o-9-9 0middot9-10

680 120 762 844 920

)24337346 366 390

56 $6 56 57 $7

09 os o8 oa 07

)89401 410 431454

367~ 357348 34o 322

1400 1J6o l36o 1310 1170

843 820 7957So 67~0

0-9-ll 0-912

1001 1100

41 bull 7 45-3

s 7 6~0

06 os 480 $18

299 268

980 65$

560 36~5

1-4-1 1-4-21-4-l1-4shy1-4-5 1-4-6 l-4-7 1 4-8 1-4-9 1-4-10 1middot4-ll 1-4bull12

354middot452 562 62q 674shy102 752 760- 863 932

1022 1100-

)82389 4014oa 416 41--7 423 428 44-2 45-7 486 49-2

51S757 51 5-7 5middot15zs sa $8 58 59

07 07 06 06 06 06 06 os o bull o 04 o J

446 45-)46middot4 471 ti7-9480 q86 491505 $19 548 55-4

)28 320 311 306 300 295 291 286 269 2582iimiddot21 bull

1080 14Lo 1550 153-5 1470 141-0 1385 1310 1310 1230 1120 855

970855 875 91-0 94~0 975 966 995 860 77-S 610 4fo

0 ~

Appendix B ORIGINAL DATA (Contirmed)-Run Speed Pressure Elevation Velocity Total Flow Line Line

Number Head Head Head had Potential Current rtjjmbull t~ bttec vyfs am~a12) ( ) ti fli 8

1-6-l $6 33$ $6 0bull9 400 364 1100 93 0 1-6-2 41 34laquo2 $6 oa 406 JS7middot iios a5s l-6-3 500 3~0 5bull6 os 356 1 1 o aos 41middot~1-6~4 35bull4 5-6 oa 41middot 352 16~0 82 0 5~1-6-5 5 bull 36_2 Sbull6 08 42bull6 349middot 161 ~ 0 86~0 1-6-6 622 366 $6 oe 43bull0 345middot 158 0 88~$ 16-A 649bull 37bull1 56 os 43-S 342middot 1570 895 1~- 386 57 07 46-0 192 ) 125A44 333middot 1-6-9 3) 404 5middot1 07 468 317 1620 675 1610 911 42-4 5-7 o6 48-7 298 168 0 61 0 1-6-11 999 451 56 os Sl ll 276 ~2-0 530 1-612 1115 485 58 04 54middot7 238 90 )3 0

1middot9-l 355 279 56 10 )45 385 1040 870 1-9-2 399 28J $6 10 )49 38$ 1140 86 5 l-9-3 ~ ao 291 56 ~0 35middot1 J8J_ JJ6o 815 1bull9-4 579 303 56 09 )68 375middot J4JO 830 l-9bullS 40- 313 )6 09 31middot8 370- 1460 82~0 1-9bull6 679 2) 56 09 3 bull8 364middot 1670 710 l-9-7 682 319 56 o9 384 ) 62 1460 79 5 l-9-8 724 33middot5 56 o8 399 3$6 bull 1480 76 -5 1-9-9 762 34middot3 $6 0 bull 8 407 )48 14910 13middotS 1-9-10 833middot )60 5middot7 os 42$ 339 144$ 686 1-9-ll 926 39middot1 5-7 07 455 318 1290 600 1-9-12 1000 41middot3 0-6 476 298 1115 510$ ~ 1middot9-13 1105 452 s o4 $14 2$6 710 )10

~

Appendix Bt ORIGDIAL J (Continued)

Run Speed Pressure Elevation Velocity Total Plow Line Line Number Head ltead Head jlamp$d P()ten~ibulll Current

r~~~m ft ft lbs~seo voltattj rgj twimiddot t 1 t2gt lt3 ou t ( rt

2-9-1 384 289 S 6 10 35 5 1400 1170 810 2-9-2 443middot 29$ $6 ltimiddot9 360 379middot 11(0 87$ 2-9-J 536 30bull 3 sc 09 )68 374middot 1)40 84 bull) 2-9-4 571 306 $6 09 3~1 372 120bull 0 955 2-9-5 623 316 S6 09 J l )6S UJSo 77$ 2bull9-6 669 327 S6 09 )92 )61 1240 905 2-9bull7 712 )39 56 os 40-3 351 12(0 86 bull0 2-9-8 ~5$~ J48 56 oa 412 348 1290 81 bull ) 2-9-9 04 )63 56 oa 42-7 339 12ltJO 76$ 2middotmiddot9-10 8$2 376 5middot1 07 440 33~- ~ o 710 2-9-11 955 394 5-1 o6 457 300 1100 506 2middot9-12 1000 421 $7 06 48middoti 295 1020 $18 2-9bull13 110~ 463 56 05 $2 267 620 3~0

oshy0

Appendix Gt CALCULATED DAgA

Turbine Run Generator Generator Turbine Turbine Efficiency Turbine Turbine Specit1c

Number OutputKWlt21

Loa~Jes KWlol

Outut K bull (H)

Input RP 12)

middot Percentlt13gt

Speed r~Jmiddot(

0ltput HP ~1

Speed r-m

( 6) middot

o-4-1 0middot4-2 0-4-3 0-4-4 0-4-5 0-4-6 O-qmiddot7o-4-8o-4-9 0-4bull10 0-4-11 o-4-12

1018 1o9a 1220 1)62J40214oa1J4oo 1357 1320 1164 997 718

046 o59 071 092 096 1071oo 134 104 100 109 107

14261sso 17)01948 2008 20322011 1999 19 09 1708 14-84 11o6

281279 27-7 276 215 273271 268 268 26h 258 24-5

soa 555 62$ 705 7)1145 742 74-6714645 51s 45-1

440 sos 585 720 195 sso sao 9$$ 985

1065 1135middot 1230

318 357 319 416 422 419412 39middot9 378 324 260 191

102 12bull4 148 191 21bull 3 22o 233 249 24924middot9 238 221

0-4middot13 418 104 699 228 306 1300 117 18)

o-6-1 982 045 1376 271 $08 496 376 124 o-6-2 o-6-3 G-6-4o-6-5 0-6-6

1023 1200 13 73 J415 139h

051 0middot66 oaa ()bull 96 088

14-39 1696 1958 2026 1986

276 27middot4 273 278 274

$20 61 8 717 7)0726

q95615745 8)5685

390 ll5middot3 sos soo 490

127 170 218 243 2$$

o-6-7 o-6-8 o-6-9o-6-lo

1288 1199 1032 7-45

o9o 094 09$ 096

1846 1733 1511 1128

274 276 271 260

67S 629559 43middot4

980 1085 1165 1245shy

436 )83316 21bull 7

266 276 270 239

0-6-11 322 1oo 566 2141 2JS 1350 101 177 0 --4

Appendix C CALCULATED DAlA ( Continued)-Run

Number Generator Generator

Out2ut Losaes xw LW- 12gt (lO)

Turbine Out2ut

ltPlJ

Turbine Inat lfP Jig)

Etpound1e1ency

PireentDl

Turbine Sed x-~m( 1

Turbine OutEut RPJl)

Turbine Specific

SeeedrIbullntbull

( 6)

o-9middot1 0-9-2 0-9-3 o-lt)-4 09-$ 0bull9-6 0-9-7 0-9-8 0-9-9 0-9-10 o-9-11 0-9-12

aao 994

111$ 1197 1206 1180 11)21081 982 784 5-49 2)9

0middot45oss o6$ 070 07$ 0-77 (l77 or~ o s06o 8 096

123~ 1402 1$80 1698 17bulllS 168$ 16bull18 ~middot5430 1151 a~J4 9

24middotgt24middot3248 25~25 260 260 259 267 266 26middot1 2S2

sos 577 63-7 671 676 650 621 60036J4

327 178

$) 610AlO 3$

92S 980

102$ 1070 1157middot 1230 1300 137Smiddot

44middot4 soo 523 ssomiddot 540so6 46-5 432 368 274 18~8

J46 176 21-1 255 2802s_A 28 289 288 265 231 168

1-4-1 1-4middot2 1-4-3 1-4-4 1-4-5 1-4-6 1-4-7 1-J-8 1-4~9 1-4-10 1-4-11 1-4-12

10bull48 1231 13-S6 1397 1)821375 1))8 1303 1127 953 683) 51

048 067 o7A07 0 bull79 oa1 oss o bullao osa 0lt)0 096 099

J468 1740 1921 1978 1958 19$1 1911 lSSi162 1)98 1045

603

266 264 262 262 261 2512$7 2$6 24middot7 24-3 233 217

551 660 13middot3155 75-6 7~-97 middot4 72$ 67 51middotJ 44middot9 21middot1

475 605 A4220

875middot 910 970_

1000 1090bull 1166 1243 1330

5816

44middot444middot5 430 427 412 392 329 273 188 l0-7

117 101 204 22$ 2)7245 2562sa 257251 222 179

a-C))

Appendix Ct CALCULATED -DATA ( Ocntinued)

1-6middot1 1023 o$2 14-41 26S 505 41~6 26~

54middot5 13middot3l-6-2 1201 067 1boo 625 47-9 17shy~middot41-6bull3 1296 oA9 1 middot43 26 9 700 so5 20bull 4 l-6-4 l3j5 o 0 19~09 268 71bull3 A5o 514 222 1-6-5 1) 5 o81 19(gt4 271 725 51-5 238 l-66 1398 081 198) 27-0 736 8 S13 252~-middot l-6j 1405 083 199i 211 733 885 $middot06 2$9 l-6 13middot9~ 103 2amp 0 279 71 8 985~ 467 ~-69 1228 1 bull 02 17-SS 270 661 109$ 407 ~3~ l-6bull10 1025 100 lSll 26i 573 1175middot 27~S32middot~l-ampu 153 1-00 llft3 26 444 1270 22 24bull8 1bull6-12 294 100 52a 231 22 3 1360 95 172

1-9bull1 904 048 1275 2J4Z $28 S4$ 459 1$2 1-92 98$ oss 13-92 24middot4 57-0 6JO 49bull1 176 1-9middot3 1110 066 1$76 24middot9 63middot4 I2o 536 21-7 l--9-4 1187 072 1685 251 66$ 5 $$ bull 0 261 1middot9-5 llltJ7 1710 25middot4 67-3 93$ 536 28~20-671middot9-6 1186 o 8 1708 25-7 67) 980 $15 2691-9- 1161 oBo 1660 2$middot3 6$6 990 508 29-1 l~- ll-32 oB) 16sect0 2$8 632 1030 471 291 1-9bull9 109$ oa5 2$7 614 1075 29S~middot 0 4imiddot41-9-10 9~91 oas 262 S$1 1150~ 3 o 292 1-9-11 o9o u57 12JiO 21gt 26-77middot74

-45 26sect ~middot91-912 $69 091 sas 25 middot3 1)0$ 196 2J-8 1-9-1) 220 098 426 2)9 178 1390middot 84 16 6

0 0

Appendx C CALCULATED DATA (Continued)

Turbine Run Generator Generator lurbine Turbine Eft1e1eney Turbine lurbine Spee1f1c

Number Output Losses Outit Input Speed Output SPed middot k_-V KW R _ H_bull_P Percent r Thm HP rpm_ (9) tlo) 11) middot (12 _) (lJI ( ) (1$ (14)

2-9-1 9--46 055 1)62 258 528 580 164 2-9-2 1024 056 248 58 4 665 4 9 191iimiddot48 4~middot0 2-9-3 1132 067 05 2$0 641 795 52q 237 2-9-4 1148 065 1027 2$1 -~8 845 525 252 2-9-5 11 77 oso 16-83 253 6 910~ 522 270 2-9 6 1122 071 1600 251 622 960 47-5 2722-9-A 1092 015 1562 257 608 1010 445 2z12bull9- 1052 079 1514 261 580 1060 41middot7 2 2 2middot9-9 986 o82 ]429 26) 542 1105 372 277 2-9-10 915 086 1340 268 500 1160 334 27-6 2-9-11 638 087 972 254 )81 1270~ 229 250 2-9-12 )28 090 828 259 )19 1295 179 226 2-9-13 192 094 383 2$ 6 150 1370 7 3 152

-3 0

Page 33: The Effect of A Variable Draft Tube Flow Area on the

26

B Intrumentat1on ~ eaeur1ng Devices

The pressure head at inlet to the turbine vaa meaave4

bymeane ot two )6 inch waterbullmeroury manometerbull connected

in series as shown in Figure 8

The terminal voltage ot the generator vas meaeured by

a laboratory voltDleter with a range to )00 yolta and callbull

brated to within 15 Yolta

The armature current bull and hence the line current was

measured by a laboratory ammeter with a range to 150 amperea

and callbrated to w1 thin o 7S amperes

Tae rate ot tlow was established by weight and time

meaeurementa The weighing ank has a capacity ot 121 000

poundsJ the weight belng indicated by Toledo direct reading

scales Timing was done with a hand atop watch with clivibull

aion ot 02 second

he ~ater level in the tailrace was dete~1ned by a

hook gauge lhie was read to the nearest 001 toot

The turbine and generator speeds were eaaured by a

hand tachometer The technique of almost cont1nuoua readbull

ings of the speed gave an error ot no more than 5 revolubull

tiona per minute

c Operational Procedure

Atter the water level in the aump was checked to

insure an adequate auppl7 the puapa were primed and

27

Figure 7 - Test Generator and Plattorm

Figure middot8- Instrument Board and Field Rheostat

28

started After venting they were valved for operation 1n

parallel

The motor generator set was started to supply the

field current and the circuit breaker was closed Water

wa added to the water rheostat to the level shown in

Figure 10 ~ field current wae minimized by cutting in

all the f ield resistance in the field rheostat of Figure 8

The l2 inch gate valve shown in Figures 5 and 6 waa

slowly opened and the turbine and generator brought up to

speed The 12 inch gat valve and turbine were vented and

the pumps were checked to insure neither had lost ita prime

lhe water rheostat offers very steady load 1f the

water level is essentially constant and the water temperabull

ture 1a fixed () p 488~89) In order to maintain this

constant temperature it was decided not to circulate the

water in the rheostat but rather to allow the water to

boil thua achieving the desired result A standing wave

was set up on the face ot the electrode by the boiling

action but a atable load was eatablished except at very

low water leYels where th11 agitation led to fluctuationa

in the line current

After putting the turbine and generator on the line

maximum power was dissipated in the rheostat by redueing

the turbine speed to between oSO and Soo revolutions per

minute Salt vas added to the rheoetat wat r to increasemiddot

29

Figure 9 - View of Water Rheostat

Figure 10 - View of Water Rheostat

Separate Field ExcitationFrom Motor-Generator set Compound Water-Mercury

---shy

re Manometer

I Q)

~ 0

~

Book Gauge

Open Channel

I

Slap Reservoir

Figure 11 - Wat~r Flow Diagram and Electrical Layout

31

waiting pe~iod ot perhaps an h~ followed

while the boiling point or the water wbulls reacbe4 During

this ti+ne the manometer was vented end eheoked electrical

measur1ng 1nstlUments were connected end the hook gauge was

adjusted tor elevation

It required about two- houtte tor the generator to reach

its normal operating tempe-ratu~e_ After the water in the

rheostat and generator had reached their operating temperabull

turea it was possible to begin the taking of data

The only vaPiable which was controlled wee the turbineshy

generator speed However the upper l1ut1t of safe line

current was slightly over 100 ampJilPampPes and the eireuit

breaker would open when the current reached lOS ~ere bull

Control was exercised by means ot regulating the water

level and salt 1n the water rheo tat and the res1stsnoe of

the tield rheost t~

The etfeet ot each type ot regulation on the three

variables is shown below

Volta Aaperebull Speed

Inc Dec Inc Dee~ Inc Dec

Wa~e1 Level Inc Dec~ X

X X X X

X

Salt Concentration

Inc Dec X

X X X X

X

field Resistance

Inc Dec

X X

X X

X X

32

Jlot all methods gave the ame amount ot change in a

given variable and a period of experiment and trial led to

the following scheme starting the rune with the lowest

turbine speed the water level was high with a high amount

ot salt and the field resistance was cut completely out

Aa it became necessary to increase the speed tor each

aucceasive run either cutting in t he field resistance

decreasing the salt concentration or lowering the Vater

level would produce the desired result However decreasbull

1ng the salt concentration had to be done Without a net

gain in water which led to a tluahing procedure that was

not particularly good because cold water was introduced

which required time to heat to the boiling point Cutting

1n additional field resistance was a good method but th1a

increased the amperage possibly to the point of opening

the circuit breaker Lowering the water level was aatiashy

factol1 until the level got too low causing the current

fluctuation previously mentioned Actually it turned out

that a combination of lowering the water level and cutting

field resistance in would carry the speed from ita minimum

to 1ts maximum value it the proper choice were made each

time the speed waa to be changed At the conclusion of

each aet of runs at a high speed the water level would be

low and the field resistance high

33

TURBINE

PAD AND DECK

TAILRACE

WATER SURFACamp

CONCRETE

DRAFT TU1B INSERTS

7 5( DRAFr TUBE

FLltJI ARIA

5~ DRAFT TUBE

FLOI ARSA

Figure 12 - Sketch of Draft Tube and Test Inserts

34

Figure 13 - View of Draft Tube Insert

Figure 14 - View of Draft Tube Insert

D c __ ~s_middot hedu_le of

A number was assigned to each run The fi~st number

applies to the draft tube tlow areas

1 bull 100~ flow area or 0~ oonatriction

2 - 7S tlow area or 2$ conatr1ct1on

3 SoC flow area or so~ constriction

The second number refers to the wicket gate openings

9 over gate opening

6 bull intermediate gate opening

4 bull one h lt gate opening

The third number 14entif1ea the location of the particular

1Wl in a set ot rona made at a given dratt tube tlow area

and wicket gate opening

fnua run number 1bull4bull10 would identity this as the

tenth run ot a set made at halt gate with 75 ot the draft

tube t1ow area

Rune w re made tor a g1yen dratt tube condition

Firat tor tull 41-aft tube flow area seta ot rune were

made for the overgate halt gate and intermediate gate

conditione An insert was placed in t he draft tube and

rune based on the same gate conditions were made tor the

7S~ draft tube flow area case The insert was then changed

to allow only $~ draft tube flow area

The inserts are sketched 1n Figure 12 and photographed

ln Flgurea 13 and 14 They oonaisted of circula~ segments

36

or l2 ineh plywood mount 4 on wooden legs 10 inches high

The 1nse7te were placed in position and secured by th use

ot a-clamps on the legs and the outside ot the bottom of

the draft tube The obvious disadvantage to this method

waa the neoeasity tor draining the water from the tailrace

tor a change ot 1naert The advantage vas of course the

simplicity ot design and construction

Chapter V

DATA-A Original Data

The normal data-taking crew consisted or two men

Assuming adjustments having been made to secure a certain

turbine speed (aee section on Operational Procedure) one

man would take semi-continuous speed readings with the hand

tachometer until a state or rotational equilibrium was

reached This could be only a period or two minutes up to

ten or tifteen minutes As soon as steady speed was

assured the data taking would begin The second man went

to the weighing tank Where a minimum ot three weighingamp

were made The requirement was to get three consecutive

readings such that the ditterence between tbe smallest and

largest time did not exceed 04 seconds The time to

collect a given weight ot water was then assumed to be the

arithmetic average of the three times He then went to the

hook gauge determined the hook elevation and then

recorded the data on the data sheets The first man meanshy

while had taken readings of the line voltage line current

and manometers and checked the turbine speed by multiple

readings During the length of the run all values were

38

checked to determine mean values for recording

The minimum length of one run was about five minutes

If one or more measure ants tended to drift during the run

all values wer discarded and a new run began as soon aa

qu111br1um was stabl1shedo

B -0-al_e_u_l_a_t--d Data

The h d on the tu~bine 1 defined by

($)

The maxtmwm velocity V4 was equal to about o8 tampet per

secon4 which makes it a negligible quantity when converted

into velocity head

An engineerbulla level was used to deterine the d1ffePshy

ence 1n elevation between the compound water-mercury manoshy

meter and the hook gauge Using this value the equation

for turbine bead becomes

where z4 is the hook gauge reading

The rate of flow 1 cent

w weight or water collected average time to collect

The inlet velocity v1 vas calculated by dividing the

weight rate or flow by the specific weight of water and the

)9

area ot ~e inlet pipe This was equivalent to dividing

the weight rate of flow by 490 Then the power input to the turbine is equal to

WHpin rri

10 (6)

Also

(P ~ut) Turbine

(P out) + Generator

(P lost) Generator

The power output of the generator is simplJ the

produot ot the terminal voltage and the armature (line)

curPent The power lost in the generator can be subdivided

into copper losses and stray power losses lo evaluate

these cunes based on losses of an identical generator

11leampsured by the Department ot Mechanical Engineering were

used The loss curves are reppoduced in part in Figures

15 and 16

Determination ot generator losses proceeds as tollowau

(1) From Figure 15 detem1ne the vo1tage drop in the

armature circuit using the temperatures of 1220 F and the

meaaured current

(2) The induced voltage is t~e sum of the terminal

voltage and the voltage drop 1n the armature circuit

() Entering the induced voltage and the turbine speed

into Figure 16 the stray power loss can be determined

(4) The copper lose can be evaluated from Figure 1$

using the measured current and the temperatlll-e of 1220 P

40

25 ~------~--------~--------~------~

U) -U) - 20

f-4 ~

-~ -gt 0

0

VOLTAGE DROP

~ - i -

- bullbullbull bull - -middot-middot -+ ~- + -t--+ ~ - ~ middotbull ~-~ middott- -+----- _ -4 middotmiddot- --~-+-t---r~~ ~--+t-t- - ---t-c-++~-ulf--

0 50 75 100

Figure 15 - Curves of Generator Voltage Drop and Copper Loss

41

1200

1000

800

600

800

0

0

~-

middot--~ 1shy --1 + bull l

100

I -

150 200

IIDOOED VOLTAGB (VOLTS)

Figure 16 - Curves of Generator Stray Power Loss

_ j

-bullshy -L---- shy middot -shy

250

- r

42

(5) The generator los os equal the sum of the eopp r

loss and stray power loss

~e efficiency or the turbine is taken as

etticiency u e =P out (8)Pin

~ample pound Determ1n1gg turbine Power Output

The following data are taken trom that ot Run 1-9-1

Line voltage 1040 volts Line current 870 amperesSpeed 355 revolutions per minute

The induced voltage 1a determined as follows

Line voltage 1040

Voltage drop 90 using Figure 15 with line current of 870 amperes and temperature ot 122 degrees)

Induced Toltage 1130 volta

The power output of the turbine is determined as follows

Generator output 90$0 (line voltage z line current)

Oopper loss 7 (using Figure 15 with line current of 870 amperes and temperatUe or 122 degrees)

Stray power lose 470 (using Figure 16 with speed ot 355 revolutions per miDUte and induced voltage or 1130 volts)

Turbine power output 9527 vatta

or turbine power output 1s 12z2 horsepower

43

The conversion of the calculated data to a constant

head is based on the conventional assumption of constant

efficiency regardless of turbine head For a constant head

ot 81 teet a purely arbitrary figure the tollowing relashy

tionships are ass1lJiled to be true

I ____L (9) (i)l72

(10)

For these two values the specific a peed may be combull

putedt

N t Jt VPt (11)8 243

Chapter VI

~RESULTS

A -Pr_e_ae_n_t_a_t_t_o~n g Reaultbull

Graphical presentation ot the results ot this te1t

are given as follows

Figure 17 -Turbine characteristics with 100~ dratt

tuba 1low area

Figure 18 - Turbine characteristics with 7S dratt

tube tlow area

Figure 19 bull Comparison ot power and etticiency at

over gate conditions between 100 and

75~ draft tube flow area

Figure 20 bull COZQparison of power and ettic1ency at

halt gate conditions between 100~ and

7S~ draft tube flow area

Figure 21 bull Comparison of power and etticiency at

over gate condition between 100~ and

So dratt tube tlow area

Figure 22 - Comparison in variation ot apec1t1c

speed between 100 and 75~ dratt tube

tlow area

50

45

20

-bull - 1--shy40

bull J-~ 30

~ ex

~ 20

~~ ~ -)q

I

~ - _

- -

10~ OF DRAFT TUBE FL(Jif AREA

CONSTANT HEAD OF 8l FEST10

POIER OUTPUT EFFICIENCY SPECIFIC SPEED

0 ~--------------_--------~------~------~ 400 600 800 1000 1200 1400

TURBINE SPEED (RPM)

Figure 17 - Turbine Char~cteristics with 100 Draft Tube Flow Area

50

46

-bulllle

~ 7 ~ OF DRAFt TUBE FLOW AREA

0 -~~-rl C05STAMT BEAD OF 81 mET 1J~

POIER OOTPUT ---+- ---o ~_H EFFICIDCY ~ I shy

bull ql SPECIFIC SPEKD - ~ -

bull ~ J 10 L rmiddotr- r- -

bullz- I

~~ 30 ~~--~----~~-

20 ~ ~ middot-shy

26

~~ 25

~0 ~r-----i (

Tbull -bullshy

400 600 800 1000 1200 1400

TURBINE SPEED (R PK )

Figure 18 -Turbine Characteristics with 75 Draft Tube Flow Area

47

EFFICIENCY 60

1-----shy

-~ 50~--~--~~-~middot middot middot middot r~-~----~~~~---4~-r~-~~gtt

II

POWER~ J ~ bull bull

u I

sH

40~------+-------+---- -~~--~~-~~~~

~----~rl 1 bull

I

I

0~--------------~------_------~--------

~ -OVER GATE CONDITION

COIJSTANT HEAD OF 81 FEET

0 o 10~ DRAFt TUBE

_-- _ 7~ DRAFT TUBamp FLON AREA II

10_~-----+--------r-------r----~~

400 600 800 1000 1200 1400

TURBINE SPEED (RPM)

Figure 19 middot - Comparison between 75 and 100 Draft Tube Flow Areas of Power and Efficiency at Over Gate Conshydition

48

t

bull --4 r ~- ~ middot~

70 1-----------+-~~~~~+middot ~ ~~ middot middot -~~--~~--------~~----~-+1

-~-

Atbull bull

lla-

60

amp0

40

20

10

oampOO

t _ - - ~-+- - -~-

l2 GATB COJIDITIOJJ

COJISTABT HJW) OF 81 JBET

o 0 lOQ( DRAFl TUB8 FLOI AREA

e-- - e 75 DRAFT TUBE FLOW AREA

800 1000

- r-

~

TURBIbull SPBIID (RPII)

Figure 20 - Comparison between 75 and 100 Draft Tube Flow Areas of Power and Efficiency at Half Gate Conshydition

49

60

50

-40

bull 30

IIQbull

20

10

0

400

- t - ~

EFFICIENCY

_J bull - bull bull

~ r r middot t -+ shy L -t -

OVER GAD COliDITIOI

CONSTABT BEAD OF 8l FBB

o o 10~ DRAFt TUBE FLOI ADA middot--- 5~ DRAF TUBE FLQPi AREA

600 800 1000 1200

Figure 21 -Comparison between 50~ and 100~ Draft Tube Flow Areas of Power and Efficiency at Ove~ Gate Conshydition

50

25

20

15

10

0

Figure 22

~- T -4 -t- -l --~-

t-~ I

middot --~- t ~---- _ __ _ + --

----~- --r-- --

~-=J-~-=-~ -==~ _ ~- -- ---f---1 - shy

CONSTANT HEAD OF 81 FEBT

o--o 1~ DRAFT TUBE FLltll AREA

75C DRMT TUBK FLCIJ AREAmiddot--middot-middot 600 800 1000

TURBINE SPEED (RPK)

Comparison of Specific Speeds for 75 and 100 Draft Tube Flow Areas

51

B Discussion 2 Result

Consideration of Figures 17 and 18 indicates the

overall eftioi ncy pattern or hill is significantly or

rounded for the 7$~ flow area than for the 100~ flow area

bia implies a greateP efficiency is possible at speeds

leas than or greater than design speed with an insert in

the draft tube However the muilDum efficiency is lemiddotas

Direct comparison at over gate conditions is made in

Figure 19 ~e same general trend is noted tor both the

etticiency and power curves for the 7$~ flow area case

The eurves show higher values at overspeed than do the

correaponding cWvea for the 100 flow area case It ia

not clear whether the curves have been shifted by the dratt

tube constriction or whether the curves simply bulge past

the normal curves at both overspeed and underspeed condishy

tions The power curves apparently peak near the aeme

point bullalthough maximum power is still obtained with the

normal draft tube area

For the comparison at halt gate operation shown in

Figure 20 a general improvement has apparently been made

by restriction of the draft tube flow area At every speed

the etticienoy and the power is greater for the restricted

tlow case The two ett1o1ency curves and two power curvea

are practically parallel throughout the speed range ot

teat

As the flou aroa i e decreased still farther a s1gn1

ticant change appears Reterr1ng to Figllle 211 tor the $0

flow area curves it a obvious that exit losses have

become excessive at the overgate condition because the

efficiency and power are everywhere leas than tor the case

of normal draf t tube area

Earlier it was pointed out t hat 1t the r esult s 1nd1bull

eated an increase in both power and ef tieiency- t hen it

could be assumed tha t the additional los s i ntroduced with

the draft tube insert is less than the diminished losses

due to leas shock losa and water passage losses For the

places where both the efficiency and power have been

increased we can assume that the insert has improved turshy

bine performance

For the places where the power haa been decreased

nothing can be said as to the elimination of ampbock loss

because the new lose present with the drat tube insert has

overshadowed any gains in eftecti Ve head upatJ-eam of the

insert

Near the peak of the efficiency hill howeve~ it may

be pointed out t hat shock loaa ie a minimum with a normal

draft tube and the insert merely adds an additional loss

with the resultant decrease in maximum efficiency tor the

7$~ flow area case

Perhaps the most s1gn1ticant set of eurves is shown aa

53

Figure 22 In this graph values of specific speed tor the

75 and 100~ flow area cases for both over gate and one

halt gate openings are plotted against turbine speed At

every speed and both gate openings the value ot specific

speed for th 75~ flow area case is greater than that for

the 100 t1ow area ease

Since the head is a constant for both situations this

may be interpreted in either of two ways trom equation

(11)

(1) For the same turbine apeed restriction of the

draft tube t1ow area resulted in greater turbine power

(2) For the same power amputput the turbine with 75~

draft tube flow area operated at a greater speed than did

the one with 100 flow area

Since the required diameter of a turbine varies

inversely with the speed the second interpretation could

be stated such that a smaller turbine could be used to

develop the same power output

Whether viewed trom the aspect of increased power

greater speed or reduced size the performance of the turshy

bine with reduced draft tube flow area is superior to that

with the nolmal flow are in the draft tube

The curve of specmiddotific speed versus turbine speed for

the so draft tube flow area case at over gate cond1t1ona

was not included in Figure 22 This curve lies below that

for the 100~ flow area c se at all speeds

In elaboration ot the second interpretation of Figure

22 attention is directed to the relative magnitudes ot

increased apee1f1c speed tor the two gate openings Assumbull

ing that the increase in specific speed implies a shift ot

the power curve to the right along the turbine speed scale

the power curve would be shifted more tor tbe halt gate

opening than tor the over gate opening

It thia trend could be extrapolated to the other gate

openings the tendency can be seen tor the line ot beat

speed to rotate toward the line of the operating speed as

illustrated in FigtU-e ) The advantage of this has already

been discussed

This particular turbine has a low specific speed tor a

reaction turbine Aa the rated value of apecitic apeed tor

reaction turbines increases the line ot beat speed departs

even more radically from the line of operating bullpeed It a

test similar to this were conducted on a reaction turbine

ot gleater specific speed it is pJobable t hat the rotation

ot the line of beat apeed would become more p~onounced

The scheme used in th1a teat had two obvious dr wbull

backs The first was the decision to leave all the wicket

gamiddottes installed tor all conditions ot the draft tube

These gates predominated in control of the tlow The

inserts added to the draft tube merely acted as auxiliary

55

contrGla

The aecond drawback was the choice or device to place

in the draft tube The reasons foll selection of this type

of device have been previously mentioned It is to be

anticipated that adaptation ot dratt tube flow control

would result 1n a better device for an actual turbine

installation Such apparatus might take the form of a

pneumatic bladder or a h7drau11oally operated variable

venturi section in the draft tube It is conceivable that

the gate as used in this test might be adapted also

Chapter VII

OONCLtJSIOfS

From the results of this test the following eonolubull

e1ona aa to the effect ot a variable draft tube flow area

on the performance or a r action turbine may be drawn

(1) The effect ot a variable draft tube tlow area 1a

generally favorable upon the operat1Gn ot a reaction turbull

bine because or the tendency tor the line or beat speed to

rotate toward the line ot operation This resulte in

better performance of the turbine at partbullloads

(2) he etf1o1ency eh111 tor the turbine beeomaa JDore

tlat at the top leading to a smaller max1JilWD effic1enc7

but e reater etticieney at other pointe of operation with

the insertion ot an auxiliary control ror the rate ot tlov

in the draft tube

(3) The power output of the turbine will increase at

over speed over gate conditione as well a at part gate

conditions with the proper amount or draft tube eonatr1cbull

tion or flow

(4) It is possible to eliminate at least partially

eddy type shock loss by tho introduction ot flow control

in the draft tube

BIBLIOGRAPBl

1 Addison Herbert A treatise on applied h-draul1cs New York Wiley 1954 724 Pbull

2 Allen o M and I A Winter middot Co111parative testa on experimental draft tubes Tranaact1ons ot the American ociety ot Civil Engineers 87t893bull970 1924

3 Barrows a E Water power engineering 3d ed ew York McGraw-Bill 1943 791 Pbull

Bovet G A Modern trenda in hydraulic turbine design4middot in Europe Tranaactions of the American Society ot Mechanical Engineera 75975bull993 1953bull

s Oreager William P and Joel D Justin Hydroelectrichandbook 2d ed New York Wiley 19$0 1151 Pbull

6 Daily Jamea w Hydraulic machinery Int Hunter Rouses Engineering hydraulics Hew York Wiley 19$0 p 8$8bull99

Daughertybull Robert L Bydraulie turbines ew Yorkbull7middot MoGrav-Hlll 1920 281 Pbull

8 Daugherty Robert L Inveat1gat1on of tne performance ot a reaction turbine ~anaactiona or the American Society ot Civil Engineers 7811270bull1304 1915

9 Davie L M Model and prototype testa Int Trend in hydraulle turbine practice symposium lranaactions ot the American Society ot Civil Engineers 1o63S3middot368 1941

lfJ Doland James J Hydro power engineering Hew Yorkbull Ronald 1954 209 Pbull

11 Gandy Theodore s and Elmer c Schacht Direct curshyrent motor and generator troubles operation and repair New York McGraw-Bill 1911 293 Pbull

12 Gibaon Arnold H Hydraulics and ita applications5th ed London Constable 1952 813 Pbull

58

13 Button s P Component loases in Kaplan turbinebull and The prediction of efficiency from model tests Probull coedings of the Institution or Mechanical Engineers168743-762 1954

14 Knapp R T~ Oavit t1on mechanics and its relation to the d sign or hydraulic equip ent Proceedings or tne Institution ot Mechanical Engineers 166150bull16) 1952

15 Langsdorf Alexander s Principles of direct curHnt mach1nee 5th ed New York r~cGrawbullH1ll 1940 746 Pbull

16 Lsrner Chester w Characteristica of modern hydraubull lie turbines Trans e~ions of the ~~erican Society ot Civil Engineers 66306-386 1910

17 Linsley Ray K Jr and Jobulleph B Franzin1 Eleshyments of hydraulic enginebullring New York McGrawshyBill 19$5 $82 Pbull

18 Mead Daniel w Hydraulic machinery llev York McGraw-Hill 1933 396 Pbull

19 ead Daniel w Water power engineering New York McGrawbullRill 191S 843 Pbull

20 Mockmore Charles A Part gate operation at water turbines Corvallis Oregon State College Department ot Civil Engineering 1933 11 numb leaves (Unpubshylshed typescript)

21 Mockmore Oharles A Flow characteristics in elbow dratt tubes Transactions of the Amez-ican Society ot Civil Engineers 103402middot464bull 1938

22 Moody L F Hydraulic machinery In c v Davis Handbook ot applied hydraulics New York McGrawshyHlll 1942 1082 Pbull

2) Ptau At-nold Hydrbullulie turbine handbook ld ed Milwaukee AllisbullOhalmers ManufactUIing Company 1948 70 Pbull

RheingalUI w J Recent developments in Francis turshybines Mechanical Engineering 74189-196 1952

25 Russell George E Hydraulica 5th ed New York Henry Holt 1942 466 Pbull

26 Safford A and E P- Hamilton American mixed tlow turbine and ita setting Tranampactions or the Amerieal Society of Civil Engineers 851237bull1)56 1922

27 bull Spannhake W1lhe1Dh Problems or modern pump and tur b1ne design Transactions of the American Society of Mechanical Engineers 56e22$-248 1934bull

28 Sutherlandraquo R A Better ethod or representing and middot tudying water turbine performance ~ansaetions ot thmiddote American Society of Mechanical Engineers 68t675bull 686 1946

29 Teats ot five models or draft tubes tor turbines Engineering News-Record Pbull 182-184 Aug 2 1923

30 White w M American hydztaulic turbines Mechanical Engineering S2t390bull39S 1930bull

31 White w M lhe hydraucGne rega1ner1 its developmentand appl1eat1ons 1n hydroelectric plants Meohanlobulll Engineering 43t37Sbull380 1921 middot

32 Winter I A Economic principlebull in designbull Int Trend in hydraulic urbin practice bull a ampoeiumTranaaot1ona ot the American Society ot Civil Engineerslo6332bull3S2 1941

33 Wiel1cenua G F Fluid mechan1ca or turbo-machineryNev York McGraw-Hill 1947 613 Pbull

APPENDICES

c

Appendix A

NOATIOB

A Angle between the absolute velocity vector and the tangent to the rwmer Subscripts 1 and 2 refel to entrance and exit ot the runner blade

B Angle between the relative 1elooity vector and the tangent to the rwmer Subscripta 1 and 2 refer to entrance and ezit or the runner blade

Angle between the tangent to the runner blade tip and the tangent to the runnel- Subscripts 1 and 2 reter to entrance and exit of the rt1rmer bladebull

Blade angle-gate opening conetant defined by equation (1)

e 09erall efficiency

g Gravitational acceleration assumed constant at 322 teet per second per second bull

H Turbine head detined by equation ($)

m Exit loss coeft1e1ent

Turbine speed expressed in revolutions per minute

Turbine speed under a constant head of 81 teet

specitic apeed of the turbine under a constant head ot 81 teet

p Power output in horsepower ot the tvbine

Power output of the turbine Ulder a constant head ot Sl teet

Pl- Pressure head at entrance to the tUlb1new

l1 Peripheral velocity ot the runneP Subacr1pta 1 and 2 refer to entrance and exit ot the JUnllampr blade

62

v Relative velocity reaulting trom the combination ot the absolute water velocity V and the runner periphshyeral velocity u Subscripts 1 and 2 refer to entrance and exit ot the runner blade

v] Relative velocity vector necessary to produce a tanbull gential entry into the runner blades

V Absolute water velocity Subscripts l and 2 refer to entrano and exit ot the runner blade

v2 Velocity head Subscripts 1 and 4 reter to the ~8 entrance to the turbine and the tail~ace wate~

w Unit weight ot water assumed constant at 624 pounda per cubic toot

V Weight rate ot flow in pounds per aeooncl

XX Velocity component ot ahook See Figule 2

Z Elevation head Subscripts 1 and 4 reter to entrance to the turbine and the taibace water surfacebull

Appendix B ORIGINAL DATA-Run

lfwnber

0-4-1 0-4-2 0-4-3 o-4-4 o-4-S o-4-6 0-4-7 0-4-8 0-4-9o-4-lo o-4-11 o-4-12 0-4-13

o-6-1 o-6-2 06-3 o-6-4o-6middotS o-6-6 o-6-7 o-6-8 0-6-9 o--6-lo o-6-11

Speed

rmiddot2middotbullmiddot(1)

336 38$ 451 S$9 620 669 6lt)$ 120 787 860 932

102imiddot109 bull

352 355 443middot 543middot 620 654AJs32

911 1001 1111

~essure Head rt (2)

410 410 416 426 431 43-7 439 44-9 452 467 482 soo $1 bull $

350 351 35middot7 )66 37-9 37-9 392 41 bull 3 43middot3 460 489

Elevation Bead

fjj $7 $7 $7 $7 $7 $7 51 57 5-15858 $8 58 56 56 $6565656 51 575As5a

Velocit Head

flj 07 07 07 06 06 06 06 os 05 os0404 03

09 09 oa o8 o8 os 07 07 06 o~o

Total Head rt ($)

47middot4 4A44 o 489 49-4 soo $02 $11 $14 $29 5imiddot45 2 576

41 bull $ 416 421 430 44middot3 44middot3 456 47-7 496 523551

Plow

lbtjec

326 324middot317 311 306 30029middot28 middotmiddot middot 386 275middot260 240 218

359 36~35 bull 349 345middot 339 330 318 300 273 240

Line Potential

vyqjbull 1060 1220 ~-0o 1920 2150 2000 2$60 2000 1940 18)015io11 o

1000 1100 139bull5 1760 1925 16$0 1620 1610 1540 1330 870

Line Current

amlscs 960 900 830 740 730655 70bull 0 530 660 600 5imiddot54 6 )60

982 930 860 780 ~3-545

79-5 74-5 670 560 370

P

Appendix B ORIGINAL DATA (Continued)

Run Number

Speed

Pbulltmiddotbullmiddot )

leasure Head ft(2

Elevation Head tt(J)

Velocity He-dfmiddotj

Total Bead tt($

Flow

lbstsec( )

Line Potential vo~ta( )

Line Current

amjs (sect

0bulllt)-1 0-9-2

3ll6 398

28o ~~1

$6 56

1o 10

346 347

390 365

1ooo 1190

aao 835

0-9-3 0-9-4 o-9-S

472 565 632

292 305 312

$6 s6 56

10 o9 o9

)$8 J7~o 37~7

381376 37o

1)6614oo 141o

820 ass ass o-9-6 0-9-7 0-9-8 o-9-9 0middot9-10

680 120 762 844 920

)24337346 366 390

56 $6 56 57 $7

09 os o8 oa 07

)89401 410 431454

367~ 357348 34o 322

1400 1J6o l36o 1310 1170

843 820 7957So 67~0

0-9-ll 0-912

1001 1100

41 bull 7 45-3

s 7 6~0

06 os 480 $18

299 268

980 65$

560 36~5

1-4-1 1-4-21-4-l1-4shy1-4-5 1-4-6 l-4-7 1 4-8 1-4-9 1-4-10 1middot4-ll 1-4bull12

354middot452 562 62q 674shy102 752 760- 863 932

1022 1100-

)82389 4014oa 416 41--7 423 428 44-2 45-7 486 49-2

51S757 51 5-7 5middot15zs sa $8 58 59

07 07 06 06 06 06 06 os o bull o 04 o J

446 45-)46middot4 471 ti7-9480 q86 491505 $19 548 55-4

)28 320 311 306 300 295 291 286 269 2582iimiddot21 bull

1080 14Lo 1550 153-5 1470 141-0 1385 1310 1310 1230 1120 855

970855 875 91-0 94~0 975 966 995 860 77-S 610 4fo

0 ~

Appendix B ORIGINAL DATA (Contirmed)-Run Speed Pressure Elevation Velocity Total Flow Line Line

Number Head Head Head had Potential Current rtjjmbull t~ bttec vyfs am~a12) ( ) ti fli 8

1-6-l $6 33$ $6 0bull9 400 364 1100 93 0 1-6-2 41 34laquo2 $6 oa 406 JS7middot iios a5s l-6-3 500 3~0 5bull6 os 356 1 1 o aos 41middot~1-6~4 35bull4 5-6 oa 41middot 352 16~0 82 0 5~1-6-5 5 bull 36_2 Sbull6 08 42bull6 349middot 161 ~ 0 86~0 1-6-6 622 366 $6 oe 43bull0 345middot 158 0 88~$ 16-A 649bull 37bull1 56 os 43-S 342middot 1570 895 1~- 386 57 07 46-0 192 ) 125A44 333middot 1-6-9 3) 404 5middot1 07 468 317 1620 675 1610 911 42-4 5-7 o6 48-7 298 168 0 61 0 1-6-11 999 451 56 os Sl ll 276 ~2-0 530 1-612 1115 485 58 04 54middot7 238 90 )3 0

1middot9-l 355 279 56 10 )45 385 1040 870 1-9-2 399 28J $6 10 )49 38$ 1140 86 5 l-9-3 ~ ao 291 56 ~0 35middot1 J8J_ JJ6o 815 1bull9-4 579 303 56 09 )68 375middot J4JO 830 l-9bullS 40- 313 )6 09 31middot8 370- 1460 82~0 1-9bull6 679 2) 56 09 3 bull8 364middot 1670 710 l-9-7 682 319 56 o9 384 ) 62 1460 79 5 l-9-8 724 33middot5 56 o8 399 3$6 bull 1480 76 -5 1-9-9 762 34middot3 $6 0 bull 8 407 )48 14910 13middotS 1-9-10 833middot )60 5middot7 os 42$ 339 144$ 686 1-9-ll 926 39middot1 5-7 07 455 318 1290 600 1-9-12 1000 41middot3 0-6 476 298 1115 510$ ~ 1middot9-13 1105 452 s o4 $14 2$6 710 )10

~

Appendix Bt ORIGDIAL J (Continued)

Run Speed Pressure Elevation Velocity Total Plow Line Line Number Head ltead Head jlamp$d P()ten~ibulll Current

r~~~m ft ft lbs~seo voltattj rgj twimiddot t 1 t2gt lt3 ou t ( rt

2-9-1 384 289 S 6 10 35 5 1400 1170 810 2-9-2 443middot 29$ $6 ltimiddot9 360 379middot 11(0 87$ 2-9-J 536 30bull 3 sc 09 )68 374middot 1)40 84 bull) 2-9-4 571 306 $6 09 3~1 372 120bull 0 955 2-9-5 623 316 S6 09 J l )6S UJSo 77$ 2bull9-6 669 327 S6 09 )92 )61 1240 905 2-9bull7 712 )39 56 os 40-3 351 12(0 86 bull0 2-9-8 ~5$~ J48 56 oa 412 348 1290 81 bull ) 2-9-9 04 )63 56 oa 42-7 339 12ltJO 76$ 2middotmiddot9-10 8$2 376 5middot1 07 440 33~- ~ o 710 2-9-11 955 394 5-1 o6 457 300 1100 506 2middot9-12 1000 421 $7 06 48middoti 295 1020 $18 2-9bull13 110~ 463 56 05 $2 267 620 3~0

oshy0

Appendix Gt CALCULATED DAgA

Turbine Run Generator Generator Turbine Turbine Efficiency Turbine Turbine Specit1c

Number OutputKWlt21

Loa~Jes KWlol

Outut K bull (H)

Input RP 12)

middot Percentlt13gt

Speed r~Jmiddot(

0ltput HP ~1

Speed r-m

( 6) middot

o-4-1 0middot4-2 0-4-3 0-4-4 0-4-5 0-4-6 O-qmiddot7o-4-8o-4-9 0-4bull10 0-4-11 o-4-12

1018 1o9a 1220 1)62J40214oa1J4oo 1357 1320 1164 997 718

046 o59 071 092 096 1071oo 134 104 100 109 107

14261sso 17)01948 2008 20322011 1999 19 09 1708 14-84 11o6

281279 27-7 276 215 273271 268 268 26h 258 24-5

soa 555 62$ 705 7)1145 742 74-6714645 51s 45-1

440 sos 585 720 195 sso sao 9$$ 985

1065 1135middot 1230

318 357 319 416 422 419412 39middot9 378 324 260 191

102 12bull4 148 191 21bull 3 22o 233 249 24924middot9 238 221

0-4middot13 418 104 699 228 306 1300 117 18)

o-6-1 982 045 1376 271 $08 496 376 124 o-6-2 o-6-3 G-6-4o-6-5 0-6-6

1023 1200 13 73 J415 139h

051 0middot66 oaa ()bull 96 088

14-39 1696 1958 2026 1986

276 27middot4 273 278 274

$20 61 8 717 7)0726

q95615745 8)5685

390 ll5middot3 sos soo 490

127 170 218 243 2$$

o-6-7 o-6-8 o-6-9o-6-lo

1288 1199 1032 7-45

o9o 094 09$ 096

1846 1733 1511 1128

274 276 271 260

67S 629559 43middot4

980 1085 1165 1245shy

436 )83316 21bull 7

266 276 270 239

0-6-11 322 1oo 566 2141 2JS 1350 101 177 0 --4

Appendix C CALCULATED DAlA ( Continued)-Run

Number Generator Generator

Out2ut Losaes xw LW- 12gt (lO)

Turbine Out2ut

ltPlJ

Turbine Inat lfP Jig)

Etpound1e1ency

PireentDl

Turbine Sed x-~m( 1

Turbine OutEut RPJl)

Turbine Specific

SeeedrIbullntbull

( 6)

o-9middot1 0-9-2 0-9-3 o-lt)-4 09-$ 0bull9-6 0-9-7 0-9-8 0-9-9 0-9-10 o-9-11 0-9-12

aao 994

111$ 1197 1206 1180 11)21081 982 784 5-49 2)9

0middot45oss o6$ 070 07$ 0-77 (l77 or~ o s06o 8 096

123~ 1402 1$80 1698 17bulllS 168$ 16bull18 ~middot5430 1151 a~J4 9

24middotgt24middot3248 25~25 260 260 259 267 266 26middot1 2S2

sos 577 63-7 671 676 650 621 60036J4

327 178

$) 610AlO 3$

92S 980

102$ 1070 1157middot 1230 1300 137Smiddot

44middot4 soo 523 ssomiddot 540so6 46-5 432 368 274 18~8

J46 176 21-1 255 2802s_A 28 289 288 265 231 168

1-4-1 1-4middot2 1-4-3 1-4-4 1-4-5 1-4-6 1-4-7 1-J-8 1-4~9 1-4-10 1-4-11 1-4-12

10bull48 1231 13-S6 1397 1)821375 1))8 1303 1127 953 683) 51

048 067 o7A07 0 bull79 oa1 oss o bullao osa 0lt)0 096 099

J468 1740 1921 1978 1958 19$1 1911 lSSi162 1)98 1045

603

266 264 262 262 261 2512$7 2$6 24middot7 24-3 233 217

551 660 13middot3155 75-6 7~-97 middot4 72$ 67 51middotJ 44middot9 21middot1

475 605 A4220

875middot 910 970_

1000 1090bull 1166 1243 1330

5816

44middot444middot5 430 427 412 392 329 273 188 l0-7

117 101 204 22$ 2)7245 2562sa 257251 222 179

a-C))

Appendix Ct CALCULATED -DATA ( Ocntinued)

1-6middot1 1023 o$2 14-41 26S 505 41~6 26~

54middot5 13middot3l-6-2 1201 067 1boo 625 47-9 17shy~middot41-6bull3 1296 oA9 1 middot43 26 9 700 so5 20bull 4 l-6-4 l3j5 o 0 19~09 268 71bull3 A5o 514 222 1-6-5 1) 5 o81 19(gt4 271 725 51-5 238 l-66 1398 081 198) 27-0 736 8 S13 252~-middot l-6j 1405 083 199i 211 733 885 $middot06 2$9 l-6 13middot9~ 103 2amp 0 279 71 8 985~ 467 ~-69 1228 1 bull 02 17-SS 270 661 109$ 407 ~3~ l-6bull10 1025 100 lSll 26i 573 1175middot 27~S32middot~l-ampu 153 1-00 llft3 26 444 1270 22 24bull8 1bull6-12 294 100 52a 231 22 3 1360 95 172

1-9bull1 904 048 1275 2J4Z $28 S4$ 459 1$2 1-92 98$ oss 13-92 24middot4 57-0 6JO 49bull1 176 1-9middot3 1110 066 1$76 24middot9 63middot4 I2o 536 21-7 l--9-4 1187 072 1685 251 66$ 5 $$ bull 0 261 1middot9-5 llltJ7 1710 25middot4 67-3 93$ 536 28~20-671middot9-6 1186 o 8 1708 25-7 67) 980 $15 2691-9- 1161 oBo 1660 2$middot3 6$6 990 508 29-1 l~- ll-32 oB) 16sect0 2$8 632 1030 471 291 1-9bull9 109$ oa5 2$7 614 1075 29S~middot 0 4imiddot41-9-10 9~91 oas 262 S$1 1150~ 3 o 292 1-9-11 o9o u57 12JiO 21gt 26-77middot74

-45 26sect ~middot91-912 $69 091 sas 25 middot3 1)0$ 196 2J-8 1-9-1) 220 098 426 2)9 178 1390middot 84 16 6

0 0

Appendx C CALCULATED DATA (Continued)

Turbine Run Generator Generator lurbine Turbine Eft1e1eney Turbine lurbine Spee1f1c

Number Output Losses Outit Input Speed Output SPed middot k_-V KW R _ H_bull_P Percent r Thm HP rpm_ (9) tlo) 11) middot (12 _) (lJI ( ) (1$ (14)

2-9-1 9--46 055 1)62 258 528 580 164 2-9-2 1024 056 248 58 4 665 4 9 191iimiddot48 4~middot0 2-9-3 1132 067 05 2$0 641 795 52q 237 2-9-4 1148 065 1027 2$1 -~8 845 525 252 2-9-5 11 77 oso 16-83 253 6 910~ 522 270 2-9 6 1122 071 1600 251 622 960 47-5 2722-9-A 1092 015 1562 257 608 1010 445 2z12bull9- 1052 079 1514 261 580 1060 41middot7 2 2 2middot9-9 986 o82 ]429 26) 542 1105 372 277 2-9-10 915 086 1340 268 500 1160 334 27-6 2-9-11 638 087 972 254 )81 1270~ 229 250 2-9-12 )28 090 828 259 )19 1295 179 226 2-9-13 192 094 383 2$ 6 150 1370 7 3 152

-3 0

Page 34: The Effect of A Variable Draft Tube Flow Area on the

27

Figure 7 - Test Generator and Plattorm

Figure middot8- Instrument Board and Field Rheostat

28

started After venting they were valved for operation 1n

parallel

The motor generator set was started to supply the

field current and the circuit breaker was closed Water

wa added to the water rheostat to the level shown in

Figure 10 ~ field current wae minimized by cutting in

all the f ield resistance in the field rheostat of Figure 8

The l2 inch gate valve shown in Figures 5 and 6 waa

slowly opened and the turbine and generator brought up to

speed The 12 inch gat valve and turbine were vented and

the pumps were checked to insure neither had lost ita prime

lhe water rheostat offers very steady load 1f the

water level is essentially constant and the water temperabull

ture 1a fixed () p 488~89) In order to maintain this

constant temperature it was decided not to circulate the

water in the rheostat but rather to allow the water to

boil thua achieving the desired result A standing wave

was set up on the face ot the electrode by the boiling

action but a atable load was eatablished except at very

low water leYels where th11 agitation led to fluctuationa

in the line current

After putting the turbine and generator on the line

maximum power was dissipated in the rheostat by redueing

the turbine speed to between oSO and Soo revolutions per

minute Salt vas added to the rheoetat wat r to increasemiddot

29

Figure 9 - View of Water Rheostat

Figure 10 - View of Water Rheostat

Separate Field ExcitationFrom Motor-Generator set Compound Water-Mercury

---shy

re Manometer

I Q)

~ 0

~

Book Gauge

Open Channel

I

Slap Reservoir

Figure 11 - Wat~r Flow Diagram and Electrical Layout

31

waiting pe~iod ot perhaps an h~ followed

while the boiling point or the water wbulls reacbe4 During

this ti+ne the manometer was vented end eheoked electrical

measur1ng 1nstlUments were connected end the hook gauge was

adjusted tor elevation

It required about two- houtte tor the generator to reach

its normal operating tempe-ratu~e_ After the water in the

rheostat and generator had reached their operating temperabull

turea it was possible to begin the taking of data

The only vaPiable which was controlled wee the turbineshy

generator speed However the upper l1ut1t of safe line

current was slightly over 100 ampJilPampPes and the eireuit

breaker would open when the current reached lOS ~ere bull

Control was exercised by means ot regulating the water

level and salt 1n the water rheo tat and the res1stsnoe of

the tield rheost t~

The etfeet ot each type ot regulation on the three

variables is shown below

Volta Aaperebull Speed

Inc Dec Inc Dee~ Inc Dec

Wa~e1 Level Inc Dec~ X

X X X X

X

Salt Concentration

Inc Dec X

X X X X

X

field Resistance

Inc Dec

X X

X X

X X

32

Jlot all methods gave the ame amount ot change in a

given variable and a period of experiment and trial led to

the following scheme starting the rune with the lowest

turbine speed the water level was high with a high amount

ot salt and the field resistance was cut completely out

Aa it became necessary to increase the speed tor each

aucceasive run either cutting in t he field resistance

decreasing the salt concentration or lowering the Vater

level would produce the desired result However decreasbull

1ng the salt concentration had to be done Without a net

gain in water which led to a tluahing procedure that was

not particularly good because cold water was introduced

which required time to heat to the boiling point Cutting

1n additional field resistance was a good method but th1a

increased the amperage possibly to the point of opening

the circuit breaker Lowering the water level was aatiashy

factol1 until the level got too low causing the current

fluctuation previously mentioned Actually it turned out

that a combination of lowering the water level and cutting

field resistance in would carry the speed from ita minimum

to 1ts maximum value it the proper choice were made each

time the speed waa to be changed At the conclusion of

each aet of runs at a high speed the water level would be

low and the field resistance high

33

TURBINE

PAD AND DECK

TAILRACE

WATER SURFACamp

CONCRETE

DRAFT TU1B INSERTS

7 5( DRAFr TUBE

FLltJI ARIA

5~ DRAFT TUBE

FLOI ARSA

Figure 12 - Sketch of Draft Tube and Test Inserts

34

Figure 13 - View of Draft Tube Insert

Figure 14 - View of Draft Tube Insert

D c __ ~s_middot hedu_le of

A number was assigned to each run The fi~st number

applies to the draft tube tlow areas

1 bull 100~ flow area or 0~ oonatriction

2 - 7S tlow area or 2$ conatr1ct1on

3 SoC flow area or so~ constriction

The second number refers to the wicket gate openings

9 over gate opening

6 bull intermediate gate opening

4 bull one h lt gate opening

The third number 14entif1ea the location of the particular

1Wl in a set ot rona made at a given dratt tube tlow area

and wicket gate opening

fnua run number 1bull4bull10 would identity this as the

tenth run ot a set made at halt gate with 75 ot the draft

tube t1ow area

Rune w re made tor a g1yen dratt tube condition

Firat tor tull 41-aft tube flow area seta ot rune were

made for the overgate halt gate and intermediate gate

conditione An insert was placed in t he draft tube and

rune based on the same gate conditions were made tor the

7S~ draft tube flow area case The insert was then changed

to allow only $~ draft tube flow area

The inserts are sketched 1n Figure 12 and photographed

ln Flgurea 13 and 14 They oonaisted of circula~ segments

36

or l2 ineh plywood mount 4 on wooden legs 10 inches high

The 1nse7te were placed in position and secured by th use

ot a-clamps on the legs and the outside ot the bottom of

the draft tube The obvious disadvantage to this method

waa the neoeasity tor draining the water from the tailrace

tor a change ot 1naert The advantage vas of course the

simplicity ot design and construction

Chapter V

DATA-A Original Data

The normal data-taking crew consisted or two men

Assuming adjustments having been made to secure a certain

turbine speed (aee section on Operational Procedure) one

man would take semi-continuous speed readings with the hand

tachometer until a state or rotational equilibrium was

reached This could be only a period or two minutes up to

ten or tifteen minutes As soon as steady speed was

assured the data taking would begin The second man went

to the weighing tank Where a minimum ot three weighingamp

were made The requirement was to get three consecutive

readings such that the ditterence between tbe smallest and

largest time did not exceed 04 seconds The time to

collect a given weight ot water was then assumed to be the

arithmetic average of the three times He then went to the

hook gauge determined the hook elevation and then

recorded the data on the data sheets The first man meanshy

while had taken readings of the line voltage line current

and manometers and checked the turbine speed by multiple

readings During the length of the run all values were

38

checked to determine mean values for recording

The minimum length of one run was about five minutes

If one or more measure ants tended to drift during the run

all values wer discarded and a new run began as soon aa

qu111br1um was stabl1shedo

B -0-al_e_u_l_a_t--d Data

The h d on the tu~bine 1 defined by

($)

The maxtmwm velocity V4 was equal to about o8 tampet per

secon4 which makes it a negligible quantity when converted

into velocity head

An engineerbulla level was used to deterine the d1ffePshy

ence 1n elevation between the compound water-mercury manoshy

meter and the hook gauge Using this value the equation

for turbine bead becomes

where z4 is the hook gauge reading

The rate of flow 1 cent

w weight or water collected average time to collect

The inlet velocity v1 vas calculated by dividing the

weight rate or flow by the specific weight of water and the

)9

area ot ~e inlet pipe This was equivalent to dividing

the weight rate of flow by 490 Then the power input to the turbine is equal to

WHpin rri

10 (6)

Also

(P ~ut) Turbine

(P out) + Generator

(P lost) Generator

The power output of the generator is simplJ the

produot ot the terminal voltage and the armature (line)

curPent The power lost in the generator can be subdivided

into copper losses and stray power losses lo evaluate

these cunes based on losses of an identical generator

11leampsured by the Department ot Mechanical Engineering were

used The loss curves are reppoduced in part in Figures

15 and 16

Determination ot generator losses proceeds as tollowau

(1) From Figure 15 detem1ne the vo1tage drop in the

armature circuit using the temperatures of 1220 F and the

meaaured current

(2) The induced voltage is t~e sum of the terminal

voltage and the voltage drop 1n the armature circuit

() Entering the induced voltage and the turbine speed

into Figure 16 the stray power loss can be determined

(4) The copper lose can be evaluated from Figure 1$

using the measured current and the temperatlll-e of 1220 P

40

25 ~------~--------~--------~------~

U) -U) - 20

f-4 ~

-~ -gt 0

0

VOLTAGE DROP

~ - i -

- bullbullbull bull - -middot-middot -+ ~- + -t--+ ~ - ~ middotbull ~-~ middott- -+----- _ -4 middotmiddot- --~-+-t---r~~ ~--+t-t- - ---t-c-++~-ulf--

0 50 75 100

Figure 15 - Curves of Generator Voltage Drop and Copper Loss

41

1200

1000

800

600

800

0

0

~-

middot--~ 1shy --1 + bull l

100

I -

150 200

IIDOOED VOLTAGB (VOLTS)

Figure 16 - Curves of Generator Stray Power Loss

_ j

-bullshy -L---- shy middot -shy

250

- r

42

(5) The generator los os equal the sum of the eopp r

loss and stray power loss

~e efficiency or the turbine is taken as

etticiency u e =P out (8)Pin

~ample pound Determ1n1gg turbine Power Output

The following data are taken trom that ot Run 1-9-1

Line voltage 1040 volts Line current 870 amperesSpeed 355 revolutions per minute

The induced voltage 1a determined as follows

Line voltage 1040

Voltage drop 90 using Figure 15 with line current of 870 amperes and temperature ot 122 degrees)

Induced Toltage 1130 volta

The power output of the turbine is determined as follows

Generator output 90$0 (line voltage z line current)

Oopper loss 7 (using Figure 15 with line current of 870 amperes and temperatUe or 122 degrees)

Stray power lose 470 (using Figure 16 with speed ot 355 revolutions per miDUte and induced voltage or 1130 volts)

Turbine power output 9527 vatta

or turbine power output 1s 12z2 horsepower

43

The conversion of the calculated data to a constant

head is based on the conventional assumption of constant

efficiency regardless of turbine head For a constant head

ot 81 teet a purely arbitrary figure the tollowing relashy

tionships are ass1lJiled to be true

I ____L (9) (i)l72

(10)

For these two values the specific a peed may be combull

putedt

N t Jt VPt (11)8 243

Chapter VI

~RESULTS

A -Pr_e_ae_n_t_a_t_t_o~n g Reaultbull

Graphical presentation ot the results ot this te1t

are given as follows

Figure 17 -Turbine characteristics with 100~ dratt

tuba 1low area

Figure 18 - Turbine characteristics with 7S dratt

tube tlow area

Figure 19 bull Comparison ot power and etticiency at

over gate conditions between 100 and

75~ draft tube flow area

Figure 20 bull COZQparison of power and ettic1ency at

halt gate conditions between 100~ and

7S~ draft tube flow area

Figure 21 bull Comparison of power and etticiency at

over gate condition between 100~ and

So dratt tube tlow area

Figure 22 - Comparison in variation ot apec1t1c

speed between 100 and 75~ dratt tube

tlow area

50

45

20

-bull - 1--shy40

bull J-~ 30

~ ex

~ 20

~~ ~ -)q

I

~ - _

- -

10~ OF DRAFT TUBE FL(Jif AREA

CONSTANT HEAD OF 8l FEST10

POIER OUTPUT EFFICIENCY SPECIFIC SPEED

0 ~--------------_--------~------~------~ 400 600 800 1000 1200 1400

TURBINE SPEED (RPM)

Figure 17 - Turbine Char~cteristics with 100 Draft Tube Flow Area

50

46

-bulllle

~ 7 ~ OF DRAFt TUBE FLOW AREA

0 -~~-rl C05STAMT BEAD OF 81 mET 1J~

POIER OOTPUT ---+- ---o ~_H EFFICIDCY ~ I shy

bull ql SPECIFIC SPEKD - ~ -

bull ~ J 10 L rmiddotr- r- -

bullz- I

~~ 30 ~~--~----~~-

20 ~ ~ middot-shy

26

~~ 25

~0 ~r-----i (

Tbull -bullshy

400 600 800 1000 1200 1400

TURBINE SPEED (R PK )

Figure 18 -Turbine Characteristics with 75 Draft Tube Flow Area

47

EFFICIENCY 60

1-----shy

-~ 50~--~--~~-~middot middot middot middot r~-~----~~~~---4~-r~-~~gtt

II

POWER~ J ~ bull bull

u I

sH

40~------+-------+---- -~~--~~-~~~~

~----~rl 1 bull

I

I

0~--------------~------_------~--------

~ -OVER GATE CONDITION

COIJSTANT HEAD OF 81 FEET

0 o 10~ DRAFt TUBE

_-- _ 7~ DRAFT TUBamp FLON AREA II

10_~-----+--------r-------r----~~

400 600 800 1000 1200 1400

TURBINE SPEED (RPM)

Figure 19 middot - Comparison between 75 and 100 Draft Tube Flow Areas of Power and Efficiency at Over Gate Conshydition

48

t

bull --4 r ~- ~ middot~

70 1-----------+-~~~~~+middot ~ ~~ middot middot -~~--~~--------~~----~-+1

-~-

Atbull bull

lla-

60

amp0

40

20

10

oampOO

t _ - - ~-+- - -~-

l2 GATB COJIDITIOJJ

COJISTABT HJW) OF 81 JBET

o 0 lOQ( DRAFl TUB8 FLOI AREA

e-- - e 75 DRAFT TUBE FLOW AREA

800 1000

- r-

~

TURBIbull SPBIID (RPII)

Figure 20 - Comparison between 75 and 100 Draft Tube Flow Areas of Power and Efficiency at Half Gate Conshydition

49

60

50

-40

bull 30

IIQbull

20

10

0

400

- t - ~

EFFICIENCY

_J bull - bull bull

~ r r middot t -+ shy L -t -

OVER GAD COliDITIOI

CONSTABT BEAD OF 8l FBB

o o 10~ DRAFt TUBE FLOI ADA middot--- 5~ DRAF TUBE FLQPi AREA

600 800 1000 1200

Figure 21 -Comparison between 50~ and 100~ Draft Tube Flow Areas of Power and Efficiency at Ove~ Gate Conshydition

50

25

20

15

10

0

Figure 22

~- T -4 -t- -l --~-

t-~ I

middot --~- t ~---- _ __ _ + --

----~- --r-- --

~-=J-~-=-~ -==~ _ ~- -- ---f---1 - shy

CONSTANT HEAD OF 81 FEBT

o--o 1~ DRAFT TUBE FLltll AREA

75C DRMT TUBK FLCIJ AREAmiddot--middot-middot 600 800 1000

TURBINE SPEED (RPK)

Comparison of Specific Speeds for 75 and 100 Draft Tube Flow Areas

51

B Discussion 2 Result

Consideration of Figures 17 and 18 indicates the

overall eftioi ncy pattern or hill is significantly or

rounded for the 7$~ flow area than for the 100~ flow area

bia implies a greateP efficiency is possible at speeds

leas than or greater than design speed with an insert in

the draft tube However the muilDum efficiency is lemiddotas

Direct comparison at over gate conditions is made in

Figure 19 ~e same general trend is noted tor both the

etticiency and power curves for the 7$~ flow area case

The eurves show higher values at overspeed than do the

correaponding cWvea for the 100 flow area case It ia

not clear whether the curves have been shifted by the dratt

tube constriction or whether the curves simply bulge past

the normal curves at both overspeed and underspeed condishy

tions The power curves apparently peak near the aeme

point bullalthough maximum power is still obtained with the

normal draft tube area

For the comparison at halt gate operation shown in

Figure 20 a general improvement has apparently been made

by restriction of the draft tube flow area At every speed

the etticienoy and the power is greater for the restricted

tlow case The two ett1o1ency curves and two power curvea

are practically parallel throughout the speed range ot

teat

As the flou aroa i e decreased still farther a s1gn1

ticant change appears Reterr1ng to Figllle 211 tor the $0

flow area curves it a obvious that exit losses have

become excessive at the overgate condition because the

efficiency and power are everywhere leas than tor the case

of normal draf t tube area

Earlier it was pointed out t hat 1t the r esult s 1nd1bull

eated an increase in both power and ef tieiency- t hen it

could be assumed tha t the additional los s i ntroduced with

the draft tube insert is less than the diminished losses

due to leas shock losa and water passage losses For the

places where both the efficiency and power have been

increased we can assume that the insert has improved turshy

bine performance

For the places where the power haa been decreased

nothing can be said as to the elimination of ampbock loss

because the new lose present with the drat tube insert has

overshadowed any gains in eftecti Ve head upatJ-eam of the

insert

Near the peak of the efficiency hill howeve~ it may

be pointed out t hat shock loaa ie a minimum with a normal

draft tube and the insert merely adds an additional loss

with the resultant decrease in maximum efficiency tor the

7$~ flow area case

Perhaps the most s1gn1ticant set of eurves is shown aa

53

Figure 22 In this graph values of specific speed tor the

75 and 100~ flow area cases for both over gate and one

halt gate openings are plotted against turbine speed At

every speed and both gate openings the value ot specific

speed for th 75~ flow area case is greater than that for

the 100 t1ow area ease

Since the head is a constant for both situations this

may be interpreted in either of two ways trom equation

(11)

(1) For the same turbine apeed restriction of the

draft tube t1ow area resulted in greater turbine power

(2) For the same power amputput the turbine with 75~

draft tube flow area operated at a greater speed than did

the one with 100 flow area

Since the required diameter of a turbine varies

inversely with the speed the second interpretation could

be stated such that a smaller turbine could be used to

develop the same power output

Whether viewed trom the aspect of increased power

greater speed or reduced size the performance of the turshy

bine with reduced draft tube flow area is superior to that

with the nolmal flow are in the draft tube

The curve of specmiddotific speed versus turbine speed for

the so draft tube flow area case at over gate cond1t1ona

was not included in Figure 22 This curve lies below that

for the 100~ flow area c se at all speeds

In elaboration ot the second interpretation of Figure

22 attention is directed to the relative magnitudes ot

increased apee1f1c speed tor the two gate openings Assumbull

ing that the increase in specific speed implies a shift ot

the power curve to the right along the turbine speed scale

the power curve would be shifted more tor tbe halt gate

opening than tor the over gate opening

It thia trend could be extrapolated to the other gate

openings the tendency can be seen tor the line ot beat

speed to rotate toward the line of the operating speed as

illustrated in FigtU-e ) The advantage of this has already

been discussed

This particular turbine has a low specific speed tor a

reaction turbine Aa the rated value of apecitic apeed tor

reaction turbines increases the line ot beat speed departs

even more radically from the line of operating bullpeed It a

test similar to this were conducted on a reaction turbine

ot gleater specific speed it is pJobable t hat the rotation

ot the line of beat apeed would become more p~onounced

The scheme used in th1a teat had two obvious dr wbull

backs The first was the decision to leave all the wicket

gamiddottes installed tor all conditions ot the draft tube

These gates predominated in control of the tlow The

inserts added to the draft tube merely acted as auxiliary

55

contrGla

The aecond drawback was the choice or device to place

in the draft tube The reasons foll selection of this type

of device have been previously mentioned It is to be

anticipated that adaptation ot dratt tube flow control

would result 1n a better device for an actual turbine

installation Such apparatus might take the form of a

pneumatic bladder or a h7drau11oally operated variable

venturi section in the draft tube It is conceivable that

the gate as used in this test might be adapted also

Chapter VII

OONCLtJSIOfS

From the results of this test the following eonolubull

e1ona aa to the effect ot a variable draft tube flow area

on the performance or a r action turbine may be drawn

(1) The effect ot a variable draft tube tlow area 1a

generally favorable upon the operat1Gn ot a reaction turbull

bine because or the tendency tor the line or beat speed to

rotate toward the line ot operation This resulte in

better performance of the turbine at partbullloads

(2) he etf1o1ency eh111 tor the turbine beeomaa JDore

tlat at the top leading to a smaller max1JilWD effic1enc7

but e reater etticieney at other pointe of operation with

the insertion ot an auxiliary control ror the rate ot tlov

in the draft tube

(3) The power output of the turbine will increase at

over speed over gate conditione as well a at part gate

conditions with the proper amount or draft tube eonatr1cbull

tion or flow

(4) It is possible to eliminate at least partially

eddy type shock loss by tho introduction ot flow control

in the draft tube

BIBLIOGRAPBl

1 Addison Herbert A treatise on applied h-draul1cs New York Wiley 1954 724 Pbull

2 Allen o M and I A Winter middot Co111parative testa on experimental draft tubes Tranaact1ons ot the American ociety ot Civil Engineers 87t893bull970 1924

3 Barrows a E Water power engineering 3d ed ew York McGraw-Bill 1943 791 Pbull

Bovet G A Modern trenda in hydraulic turbine design4middot in Europe Tranaactions of the American Society ot Mechanical Engineera 75975bull993 1953bull

s Oreager William P and Joel D Justin Hydroelectrichandbook 2d ed New York Wiley 19$0 1151 Pbull

6 Daily Jamea w Hydraulic machinery Int Hunter Rouses Engineering hydraulics Hew York Wiley 19$0 p 8$8bull99

Daughertybull Robert L Bydraulie turbines ew Yorkbull7middot MoGrav-Hlll 1920 281 Pbull

8 Daugherty Robert L Inveat1gat1on of tne performance ot a reaction turbine ~anaactiona or the American Society ot Civil Engineers 7811270bull1304 1915

9 Davie L M Model and prototype testa Int Trend in hydraulle turbine practice symposium lranaactions ot the American Society ot Civil Engineers 1o63S3middot368 1941

lfJ Doland James J Hydro power engineering Hew Yorkbull Ronald 1954 209 Pbull

11 Gandy Theodore s and Elmer c Schacht Direct curshyrent motor and generator troubles operation and repair New York McGraw-Bill 1911 293 Pbull

12 Gibaon Arnold H Hydraulics and ita applications5th ed London Constable 1952 813 Pbull

58

13 Button s P Component loases in Kaplan turbinebull and The prediction of efficiency from model tests Probull coedings of the Institution or Mechanical Engineers168743-762 1954

14 Knapp R T~ Oavit t1on mechanics and its relation to the d sign or hydraulic equip ent Proceedings or tne Institution ot Mechanical Engineers 166150bull16) 1952

15 Langsdorf Alexander s Principles of direct curHnt mach1nee 5th ed New York r~cGrawbullH1ll 1940 746 Pbull

16 Lsrner Chester w Characteristica of modern hydraubull lie turbines Trans e~ions of the ~~erican Society ot Civil Engineers 66306-386 1910

17 Linsley Ray K Jr and Jobulleph B Franzin1 Eleshyments of hydraulic enginebullring New York McGrawshyBill 19$5 $82 Pbull

18 Mead Daniel w Hydraulic machinery llev York McGraw-Hill 1933 396 Pbull

19 ead Daniel w Water power engineering New York McGrawbullRill 191S 843 Pbull

20 Mockmore Charles A Part gate operation at water turbines Corvallis Oregon State College Department ot Civil Engineering 1933 11 numb leaves (Unpubshylshed typescript)

21 Mockmore Oharles A Flow characteristics in elbow dratt tubes Transactions of the Amez-ican Society ot Civil Engineers 103402middot464bull 1938

22 Moody L F Hydraulic machinery In c v Davis Handbook ot applied hydraulics New York McGrawshyHlll 1942 1082 Pbull

2) Ptau At-nold Hydrbullulie turbine handbook ld ed Milwaukee AllisbullOhalmers ManufactUIing Company 1948 70 Pbull

RheingalUI w J Recent developments in Francis turshybines Mechanical Engineering 74189-196 1952

25 Russell George E Hydraulica 5th ed New York Henry Holt 1942 466 Pbull

26 Safford A and E P- Hamilton American mixed tlow turbine and ita setting Tranampactions or the Amerieal Society of Civil Engineers 851237bull1)56 1922

27 bull Spannhake W1lhe1Dh Problems or modern pump and tur b1ne design Transactions of the American Society of Mechanical Engineers 56e22$-248 1934bull

28 Sutherlandraquo R A Better ethod or representing and middot tudying water turbine performance ~ansaetions ot thmiddote American Society of Mechanical Engineers 68t675bull 686 1946

29 Teats ot five models or draft tubes tor turbines Engineering News-Record Pbull 182-184 Aug 2 1923

30 White w M American hydztaulic turbines Mechanical Engineering S2t390bull39S 1930bull

31 White w M lhe hydraucGne rega1ner1 its developmentand appl1eat1ons 1n hydroelectric plants Meohanlobulll Engineering 43t37Sbull380 1921 middot

32 Winter I A Economic principlebull in designbull Int Trend in hydraulic urbin practice bull a ampoeiumTranaaot1ona ot the American Society ot Civil Engineerslo6332bull3S2 1941

33 Wiel1cenua G F Fluid mechan1ca or turbo-machineryNev York McGraw-Hill 1947 613 Pbull

APPENDICES

c

Appendix A

NOATIOB

A Angle between the absolute velocity vector and the tangent to the rwmer Subscripts 1 and 2 refel to entrance and exit ot the runner blade

B Angle between the relative 1elooity vector and the tangent to the rwmer Subscripta 1 and 2 refer to entrance and ezit or the runner blade

Angle between the tangent to the runner blade tip and the tangent to the runnel- Subscripts 1 and 2 reter to entrance and exit of the rt1rmer bladebull

Blade angle-gate opening conetant defined by equation (1)

e 09erall efficiency

g Gravitational acceleration assumed constant at 322 teet per second per second bull

H Turbine head detined by equation ($)

m Exit loss coeft1e1ent

Turbine speed expressed in revolutions per minute

Turbine speed under a constant head of 81 teet

specitic apeed of the turbine under a constant head ot 81 teet

p Power output in horsepower ot the tvbine

Power output of the turbine Ulder a constant head ot Sl teet

Pl- Pressure head at entrance to the tUlb1new

l1 Peripheral velocity ot the runneP Subacr1pta 1 and 2 refer to entrance and exit ot the JUnllampr blade

62

v Relative velocity reaulting trom the combination ot the absolute water velocity V and the runner periphshyeral velocity u Subscripts 1 and 2 refer to entrance and exit ot the runner blade

v] Relative velocity vector necessary to produce a tanbull gential entry into the runner blades

V Absolute water velocity Subscripts l and 2 refer to entrano and exit ot the runner blade

v2 Velocity head Subscripts 1 and 4 reter to the ~8 entrance to the turbine and the tail~ace wate~

w Unit weight ot water assumed constant at 624 pounda per cubic toot

V Weight rate ot flow in pounds per aeooncl

XX Velocity component ot ahook See Figule 2

Z Elevation head Subscripts 1 and 4 reter to entrance to the turbine and the taibace water surfacebull

Appendix B ORIGINAL DATA-Run

lfwnber

0-4-1 0-4-2 0-4-3 o-4-4 o-4-S o-4-6 0-4-7 0-4-8 0-4-9o-4-lo o-4-11 o-4-12 0-4-13

o-6-1 o-6-2 06-3 o-6-4o-6middotS o-6-6 o-6-7 o-6-8 0-6-9 o--6-lo o-6-11

Speed

rmiddot2middotbullmiddot(1)

336 38$ 451 S$9 620 669 6lt)$ 120 787 860 932

102imiddot109 bull

352 355 443middot 543middot 620 654AJs32

911 1001 1111

~essure Head rt (2)

410 410 416 426 431 43-7 439 44-9 452 467 482 soo $1 bull $

350 351 35middot7 )66 37-9 37-9 392 41 bull 3 43middot3 460 489

Elevation Bead

fjj $7 $7 $7 $7 $7 $7 51 57 5-15858 $8 58 56 56 $6565656 51 575As5a

Velocit Head

flj 07 07 07 06 06 06 06 os 05 os0404 03

09 09 oa o8 o8 os 07 07 06 o~o

Total Head rt ($)

47middot4 4A44 o 489 49-4 soo $02 $11 $14 $29 5imiddot45 2 576

41 bull $ 416 421 430 44middot3 44middot3 456 47-7 496 523551

Plow

lbtjec

326 324middot317 311 306 30029middot28 middotmiddot middot 386 275middot260 240 218

359 36~35 bull 349 345middot 339 330 318 300 273 240

Line Potential

vyqjbull 1060 1220 ~-0o 1920 2150 2000 2$60 2000 1940 18)015io11 o

1000 1100 139bull5 1760 1925 16$0 1620 1610 1540 1330 870

Line Current

amlscs 960 900 830 740 730655 70bull 0 530 660 600 5imiddot54 6 )60

982 930 860 780 ~3-545

79-5 74-5 670 560 370

P

Appendix B ORIGINAL DATA (Continued)

Run Number

Speed

Pbulltmiddotbullmiddot )

leasure Head ft(2

Elevation Head tt(J)

Velocity He-dfmiddotj

Total Bead tt($

Flow

lbstsec( )

Line Potential vo~ta( )

Line Current

amjs (sect

0bulllt)-1 0-9-2

3ll6 398

28o ~~1

$6 56

1o 10

346 347

390 365

1ooo 1190

aao 835

0-9-3 0-9-4 o-9-S

472 565 632

292 305 312

$6 s6 56

10 o9 o9

)$8 J7~o 37~7

381376 37o

1)6614oo 141o

820 ass ass o-9-6 0-9-7 0-9-8 o-9-9 0middot9-10

680 120 762 844 920

)24337346 366 390

56 $6 56 57 $7

09 os o8 oa 07

)89401 410 431454

367~ 357348 34o 322

1400 1J6o l36o 1310 1170

843 820 7957So 67~0

0-9-ll 0-912

1001 1100

41 bull 7 45-3

s 7 6~0

06 os 480 $18

299 268

980 65$

560 36~5

1-4-1 1-4-21-4-l1-4shy1-4-5 1-4-6 l-4-7 1 4-8 1-4-9 1-4-10 1middot4-ll 1-4bull12

354middot452 562 62q 674shy102 752 760- 863 932

1022 1100-

)82389 4014oa 416 41--7 423 428 44-2 45-7 486 49-2

51S757 51 5-7 5middot15zs sa $8 58 59

07 07 06 06 06 06 06 os o bull o 04 o J

446 45-)46middot4 471 ti7-9480 q86 491505 $19 548 55-4

)28 320 311 306 300 295 291 286 269 2582iimiddot21 bull

1080 14Lo 1550 153-5 1470 141-0 1385 1310 1310 1230 1120 855

970855 875 91-0 94~0 975 966 995 860 77-S 610 4fo

0 ~

Appendix B ORIGINAL DATA (Contirmed)-Run Speed Pressure Elevation Velocity Total Flow Line Line

Number Head Head Head had Potential Current rtjjmbull t~ bttec vyfs am~a12) ( ) ti fli 8

1-6-l $6 33$ $6 0bull9 400 364 1100 93 0 1-6-2 41 34laquo2 $6 oa 406 JS7middot iios a5s l-6-3 500 3~0 5bull6 os 356 1 1 o aos 41middot~1-6~4 35bull4 5-6 oa 41middot 352 16~0 82 0 5~1-6-5 5 bull 36_2 Sbull6 08 42bull6 349middot 161 ~ 0 86~0 1-6-6 622 366 $6 oe 43bull0 345middot 158 0 88~$ 16-A 649bull 37bull1 56 os 43-S 342middot 1570 895 1~- 386 57 07 46-0 192 ) 125A44 333middot 1-6-9 3) 404 5middot1 07 468 317 1620 675 1610 911 42-4 5-7 o6 48-7 298 168 0 61 0 1-6-11 999 451 56 os Sl ll 276 ~2-0 530 1-612 1115 485 58 04 54middot7 238 90 )3 0

1middot9-l 355 279 56 10 )45 385 1040 870 1-9-2 399 28J $6 10 )49 38$ 1140 86 5 l-9-3 ~ ao 291 56 ~0 35middot1 J8J_ JJ6o 815 1bull9-4 579 303 56 09 )68 375middot J4JO 830 l-9bullS 40- 313 )6 09 31middot8 370- 1460 82~0 1-9bull6 679 2) 56 09 3 bull8 364middot 1670 710 l-9-7 682 319 56 o9 384 ) 62 1460 79 5 l-9-8 724 33middot5 56 o8 399 3$6 bull 1480 76 -5 1-9-9 762 34middot3 $6 0 bull 8 407 )48 14910 13middotS 1-9-10 833middot )60 5middot7 os 42$ 339 144$ 686 1-9-ll 926 39middot1 5-7 07 455 318 1290 600 1-9-12 1000 41middot3 0-6 476 298 1115 510$ ~ 1middot9-13 1105 452 s o4 $14 2$6 710 )10

~

Appendix Bt ORIGDIAL J (Continued)

Run Speed Pressure Elevation Velocity Total Plow Line Line Number Head ltead Head jlamp$d P()ten~ibulll Current

r~~~m ft ft lbs~seo voltattj rgj twimiddot t 1 t2gt lt3 ou t ( rt

2-9-1 384 289 S 6 10 35 5 1400 1170 810 2-9-2 443middot 29$ $6 ltimiddot9 360 379middot 11(0 87$ 2-9-J 536 30bull 3 sc 09 )68 374middot 1)40 84 bull) 2-9-4 571 306 $6 09 3~1 372 120bull 0 955 2-9-5 623 316 S6 09 J l )6S UJSo 77$ 2bull9-6 669 327 S6 09 )92 )61 1240 905 2-9bull7 712 )39 56 os 40-3 351 12(0 86 bull0 2-9-8 ~5$~ J48 56 oa 412 348 1290 81 bull ) 2-9-9 04 )63 56 oa 42-7 339 12ltJO 76$ 2middotmiddot9-10 8$2 376 5middot1 07 440 33~- ~ o 710 2-9-11 955 394 5-1 o6 457 300 1100 506 2middot9-12 1000 421 $7 06 48middoti 295 1020 $18 2-9bull13 110~ 463 56 05 $2 267 620 3~0

oshy0

Appendix Gt CALCULATED DAgA

Turbine Run Generator Generator Turbine Turbine Efficiency Turbine Turbine Specit1c

Number OutputKWlt21

Loa~Jes KWlol

Outut K bull (H)

Input RP 12)

middot Percentlt13gt

Speed r~Jmiddot(

0ltput HP ~1

Speed r-m

( 6) middot

o-4-1 0middot4-2 0-4-3 0-4-4 0-4-5 0-4-6 O-qmiddot7o-4-8o-4-9 0-4bull10 0-4-11 o-4-12

1018 1o9a 1220 1)62J40214oa1J4oo 1357 1320 1164 997 718

046 o59 071 092 096 1071oo 134 104 100 109 107

14261sso 17)01948 2008 20322011 1999 19 09 1708 14-84 11o6

281279 27-7 276 215 273271 268 268 26h 258 24-5

soa 555 62$ 705 7)1145 742 74-6714645 51s 45-1

440 sos 585 720 195 sso sao 9$$ 985

1065 1135middot 1230

318 357 319 416 422 419412 39middot9 378 324 260 191

102 12bull4 148 191 21bull 3 22o 233 249 24924middot9 238 221

0-4middot13 418 104 699 228 306 1300 117 18)

o-6-1 982 045 1376 271 $08 496 376 124 o-6-2 o-6-3 G-6-4o-6-5 0-6-6

1023 1200 13 73 J415 139h

051 0middot66 oaa ()bull 96 088

14-39 1696 1958 2026 1986

276 27middot4 273 278 274

$20 61 8 717 7)0726

q95615745 8)5685

390 ll5middot3 sos soo 490

127 170 218 243 2$$

o-6-7 o-6-8 o-6-9o-6-lo

1288 1199 1032 7-45

o9o 094 09$ 096

1846 1733 1511 1128

274 276 271 260

67S 629559 43middot4

980 1085 1165 1245shy

436 )83316 21bull 7

266 276 270 239

0-6-11 322 1oo 566 2141 2JS 1350 101 177 0 --4

Appendix C CALCULATED DAlA ( Continued)-Run

Number Generator Generator

Out2ut Losaes xw LW- 12gt (lO)

Turbine Out2ut

ltPlJ

Turbine Inat lfP Jig)

Etpound1e1ency

PireentDl

Turbine Sed x-~m( 1

Turbine OutEut RPJl)

Turbine Specific

SeeedrIbullntbull

( 6)

o-9middot1 0-9-2 0-9-3 o-lt)-4 09-$ 0bull9-6 0-9-7 0-9-8 0-9-9 0-9-10 o-9-11 0-9-12

aao 994

111$ 1197 1206 1180 11)21081 982 784 5-49 2)9

0middot45oss o6$ 070 07$ 0-77 (l77 or~ o s06o 8 096

123~ 1402 1$80 1698 17bulllS 168$ 16bull18 ~middot5430 1151 a~J4 9

24middotgt24middot3248 25~25 260 260 259 267 266 26middot1 2S2

sos 577 63-7 671 676 650 621 60036J4

327 178

$) 610AlO 3$

92S 980

102$ 1070 1157middot 1230 1300 137Smiddot

44middot4 soo 523 ssomiddot 540so6 46-5 432 368 274 18~8

J46 176 21-1 255 2802s_A 28 289 288 265 231 168

1-4-1 1-4middot2 1-4-3 1-4-4 1-4-5 1-4-6 1-4-7 1-J-8 1-4~9 1-4-10 1-4-11 1-4-12

10bull48 1231 13-S6 1397 1)821375 1))8 1303 1127 953 683) 51

048 067 o7A07 0 bull79 oa1 oss o bullao osa 0lt)0 096 099

J468 1740 1921 1978 1958 19$1 1911 lSSi162 1)98 1045

603

266 264 262 262 261 2512$7 2$6 24middot7 24-3 233 217

551 660 13middot3155 75-6 7~-97 middot4 72$ 67 51middotJ 44middot9 21middot1

475 605 A4220

875middot 910 970_

1000 1090bull 1166 1243 1330

5816

44middot444middot5 430 427 412 392 329 273 188 l0-7

117 101 204 22$ 2)7245 2562sa 257251 222 179

a-C))

Appendix Ct CALCULATED -DATA ( Ocntinued)

1-6middot1 1023 o$2 14-41 26S 505 41~6 26~

54middot5 13middot3l-6-2 1201 067 1boo 625 47-9 17shy~middot41-6bull3 1296 oA9 1 middot43 26 9 700 so5 20bull 4 l-6-4 l3j5 o 0 19~09 268 71bull3 A5o 514 222 1-6-5 1) 5 o81 19(gt4 271 725 51-5 238 l-66 1398 081 198) 27-0 736 8 S13 252~-middot l-6j 1405 083 199i 211 733 885 $middot06 2$9 l-6 13middot9~ 103 2amp 0 279 71 8 985~ 467 ~-69 1228 1 bull 02 17-SS 270 661 109$ 407 ~3~ l-6bull10 1025 100 lSll 26i 573 1175middot 27~S32middot~l-ampu 153 1-00 llft3 26 444 1270 22 24bull8 1bull6-12 294 100 52a 231 22 3 1360 95 172

1-9bull1 904 048 1275 2J4Z $28 S4$ 459 1$2 1-92 98$ oss 13-92 24middot4 57-0 6JO 49bull1 176 1-9middot3 1110 066 1$76 24middot9 63middot4 I2o 536 21-7 l--9-4 1187 072 1685 251 66$ 5 $$ bull 0 261 1middot9-5 llltJ7 1710 25middot4 67-3 93$ 536 28~20-671middot9-6 1186 o 8 1708 25-7 67) 980 $15 2691-9- 1161 oBo 1660 2$middot3 6$6 990 508 29-1 l~- ll-32 oB) 16sect0 2$8 632 1030 471 291 1-9bull9 109$ oa5 2$7 614 1075 29S~middot 0 4imiddot41-9-10 9~91 oas 262 S$1 1150~ 3 o 292 1-9-11 o9o u57 12JiO 21gt 26-77middot74

-45 26sect ~middot91-912 $69 091 sas 25 middot3 1)0$ 196 2J-8 1-9-1) 220 098 426 2)9 178 1390middot 84 16 6

0 0

Appendx C CALCULATED DATA (Continued)

Turbine Run Generator Generator lurbine Turbine Eft1e1eney Turbine lurbine Spee1f1c

Number Output Losses Outit Input Speed Output SPed middot k_-V KW R _ H_bull_P Percent r Thm HP rpm_ (9) tlo) 11) middot (12 _) (lJI ( ) (1$ (14)

2-9-1 9--46 055 1)62 258 528 580 164 2-9-2 1024 056 248 58 4 665 4 9 191iimiddot48 4~middot0 2-9-3 1132 067 05 2$0 641 795 52q 237 2-9-4 1148 065 1027 2$1 -~8 845 525 252 2-9-5 11 77 oso 16-83 253 6 910~ 522 270 2-9 6 1122 071 1600 251 622 960 47-5 2722-9-A 1092 015 1562 257 608 1010 445 2z12bull9- 1052 079 1514 261 580 1060 41middot7 2 2 2middot9-9 986 o82 ]429 26) 542 1105 372 277 2-9-10 915 086 1340 268 500 1160 334 27-6 2-9-11 638 087 972 254 )81 1270~ 229 250 2-9-12 )28 090 828 259 )19 1295 179 226 2-9-13 192 094 383 2$ 6 150 1370 7 3 152

-3 0

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