WIND TUNNELWIND TUNNEL MEASUREMENTS OFMEASUREMENTS OFWIND TUNNELWIND TUNNEL MEASUREMENTS OF MEASUREMENTS OF CONVECTIVE HEAT TRANSFER WITH CONVECTIVE HEAT TRANSFER WITH

DROPLET IMPACT ON ADROPLET IMPACT ON A WINDWINDDROPLET IMPACT ON A DROPLET IMPACT ON A WIND WIND TURBINE NACA63TURBINE NACA63--421 BLADE421 BLADE

Xin Wang, Eric BibeauXin Wang, Eric BibeauUniversity of ManitobaUniversity of Manitoba

Greg NatererGreg Naterer

July 09 2007July 09 2007

Greg Naterer Greg Naterer

University of Ontario Institute of TechnologyUniversity of Ontario Institute of Technology

July 09 2007July 09 2007

2007 ASME2007 ASME--JSME Thermal Engineering Summer Heat Transfer ConferenceJSME Thermal Engineering Summer Heat Transfer Conference

OUTLINEOUTLINE

IntroductionIntroductionE i l dE i l d Experimental procedureExperimental procedure

Formulation of modified Hilpert Formulation of modified Hilpert o u at o o od ed pe to u at o o od ed pe tCorrelationsCorrelationsResults and DiscussionResults and Discussion Results and DiscussionResults and Discussion

ConclusionsConclusions AcknowledgementsAcknowledgements

2007 ASME2007 ASME--JSME Thermal Engineering Summer Heat Transfer ConferenceJSME Thermal Engineering Summer Heat Transfer Conference

IntroductionIntroduction Climate change Climate change Rising energy demandRising energy demand Rising energy demandRising energy demand Reduction of GHG emissions Reduction of GHG emissions Wind energy penetrationWind energy penetration140 Wind energy penetrationWind energy penetration

up to 12% by 2020up to 12% by 2020A l i f 14 2%A l i f 14 2%

80

100

120

140

Annual increase of 14.2%Annual increase of 14.2% Cumulative growth rateCumulative growth rate

0

20

40

60

19% prediction19% prediction0

2005 2006 2007 2005 2006 2007 2008 2008 2009 2009 20102010

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Wind icing issuesWind icing issues

Reduced powerReduced powerI i f tI i f t

Wind energy in cold climates consortium

Icing factorIcing factor Safety issueSafety issueyy

Ice fragmentsIce fragmentsWear and tearWear and tear Wear and tearWear and tear

Excess vibrationExcess vibrationCopyright: http://virtual.vtt.fi/virtual/arcticwind/index.htm

Affects Canadian wind farmsAffects Canadian wind farms

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IntroductionIntroduction EEmpirical correlations of forced mpirical correlations of forced

convection heat transfer from cylindersconvection heat transfer from cylindersconvection heat transfer from cylinders, convection heat transfer from cylinders, plates and other geometrical plates and other geometrical configurationsconfigurations are available but withoutare available but withoutconfigurationsconfigurations are available, but without are available, but without impinging droplets. impinging droplets. Water droplet distributionWater droplet distribution Water droplet distributionWater droplet distribution

WWater droplets impinging on cables or ater droplets impinging on cables or li dli d ll i d i f illl i d i f ilcylinders,cylinders, as well as wings and airfoilsas well as wings and airfoils

FForced convectionorced convection with water droplets with water droplets

2007 ASME2007 ASME--JSME Thermal Engineering Summer Heat Transfer ConferenceJSME Thermal Engineering Summer Heat Transfer Conference

Experimental procedureExperimental procedured ld l Icing Wind TunnelIcing Wind Tunnel

Velocity up to 42 m/sVelocity up to 42 m/s Temperature down to Temperature down to --3535ooCC

motor

insulatedwalls

fan cabinet turning vanes

fan

motor

heatexchanger

airflow

fan

refrigerationpiping

g

contractionsection

p p g

plenum, tes theatedplenum,screens

tes tchamber

heatedwindow

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Experimental procedureExperimental procedurep pp p

NACA airfoil with measurement pointsNACA airfoil with measurement points

40

60

80

T8

T7

T4

T3 T6

T5

T11T10

T9

h6

h5

h4h3

h2

-40

-20

0

20

0 100 200 300 400 500

T2T1

T19

T12

T1

T17

T16

T14

T13

T20

h1

h10

h7

-60

T17 T15h10 h9 h8

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Experimental procedureExperimental procedure

Airfoil dimensions:Airfoil dimensions: 33××62 5 mm in span62 5 mm in span 33××62.5 mm in span62.5 mm in span 500 mm in chord500 mm in chord

3 mm in thickness3 mm in thickness 3 mm in thickness 3 mm in thickness Thermocouples:Thermocouples:

T type thermocouples with buildT type thermocouples with build--in in compensationcompensation

i i f ili i f il 22 in airfoil22 in airfoil 1 in tunnel1 in tunnel 2 to measure zero point cell as reference2 to measure zero point cell as reference

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Experimental procedureExperimental procedure Water cooling systemWater cooling system

Set up temperature same as the flowSet up temperature same as the flow Set up temperature same as the flowSet up temperature same as the flow Water spray systemWater spray system

4 atomizing nozzles4 atomizing nozzles 4 atomizing nozzles 4 atomizing nozzles Air pressure 50 psiAir pressure 50 psi Water pressure 35 psiWater pressure 35 psi Water pressure 35 psiWater pressure 35 psi Flow controlFlow control

Variable HeaterVariable Heater Variable HeaterVariable Heater 40 mm in width and 880 mm in length 40 mm in width and 880 mm in length 0 to 500 W according to 0 to 120 V0 to 500 W according to 0 to 120 V0 to 500 W according to 0 to 120 V0 to 500 W according to 0 to 120 V

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Formulations of heat transferFormulations of heat transfer

CConvective heat transfeonvective heat transferr )( 0 TThqcon

Conductive heat transferConductive heat transfer( )in o

con cdk T Tq q

HHeat transfer coefficienteat transfer coefficient

)()(

0

0

TTTTkh in

Average Average coefficientcoefficient 1111i

ii shs

hdxs

hgg

Average Nusselt numberAverage Nusselt number

is ss

kchNu

Average Nusselt number Average Nusselt number airk

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Modified Hilpert CorrelationsModified Hilpert Correlations

Hilpert correlation for a cylinder in cross Hilpert correlation for a cylinder in cross flowflow 1/3flow flow 1/3Re PrmNu c

Modified Hilpert correlations for an airfoil Modified Hilpert correlations for an airfoil ith t LWCith t LWC0 389 1/3without LWCwithout LWC

for Re ≤ 5 for Re ≤ 5 ××101055

0.389 1/32.483Re PrNu

101055 0.636 1/30.0943Re PrNu

for Re ≥ 5 for Re ≥ 5 ××101055

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Experimental Results (low Re)Experimental Results (low Re)

700

800

Nu=2.483Re0.389Pr1/3

( ith t d l t )

600

700(0.9 < LWC < 2)

(0.5 < LWC < 0.8)

(without droplets)

400

500Nu (0.3 < LWC < 0.5)

300

400

(a)200

1.0E+05 3.0E+05 5.0E+05R

(a)

Re

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Experimental Results (high Re)Experimental Results (high Re)

900

1000(0.15 < LWC < 0.29)

(0.3 < LWC < 0.4)

800

900 ( )

(0.4 < LWC < 0.65)

Nu=0.0943Re0.636Pr1/3

(Without droplets)

600

700Nu

( p )

500(b)

400

6.0E+05 8.0E+05 1.0E+06

Re

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Experimental Results 3Experimental Results 32000

Re(1+X)=235,500 Re(1+X)=390,500

Re(1+X)=427,300 Re(1+X)=516,700

1200

1600 Re(1+X)=672,300 Re(1+X)=718,900

Re(1+X)=819,500 Re(1+X)=979,800

800

Nux

400

0

-0.7 -0.4 -0.1 0.2 0.5 0.8

Non-dimensional Chord PositionNon dimensional Chord Position

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Results and Discussion 1Results and Discussion 1 Multiphase Re: ReMultiphase Re: Remm=(1+X)Re=(1+X)Re

LWC

0LWCLWCX

LWCLWC00=1.25 when 1 ≤ LWC ≤ 2 g/m=1.25 when 1 ≤ LWC ≤ 2 g/m33

LWCLWC00=0.92 when 0 ≤ LWC ≤ 1 g/m=0.92 when 0 ≤ LWC ≤ 1 g/m33

Modified Hilpert correlationModified Hilpert correlation3

1Pr))1(Re( mXcNu

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Results and Discussion 2Results and Discussion 2 Correlations of Nusselt number with

corrected Reynolds numbercorrected Reynolds number 3

1389.0 Pr))1(Re(483.2 XNu

(for Re(1+X) ≤ 6 × 105)3

1636.0 Pr))1(Re(0943.0 XNu

(for Re(1+X) ≥ 6 × 105)

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Results and Discussion 3Results and Discussion 3

900

1000

Nu =0.0943(Re(1+X))0.636Pr1/3

700

800 Experiment

400

500

600Nu

200

300

400

200

6.0E+05 1.0E+06 1.4E+06

Re (1+X)

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Results and Discussion 4Results and Discussion 4

900

1000

0 389 1/3

700

800Nu

Experiment

=2.483(Re(1+X))0.389Pr1/3

500

600Nu

300

400

200

2.0E+05 3.0E+05 4.0E+05 5.0E+05 6.0E+05Re (1+X)

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ConclusionsConclusions The multiphase Reynolds parameter is The multiphase Reynolds parameter is

shown to provide normalization againstshown to provide normalization againstshown to provide normalization against shown to provide normalization against singlesingle--phase correlations over a wide phase correlations over a wide range of Reynolds numbersrange of Reynolds numbersrange of Reynolds numbers. range of Reynolds numbers.

31389.0 Pr))1(Re(483.2 XNu

16360

An uncertainty analysis was performed to An uncertainty analysis was performed to

3636.0 Pr))1(Re(0943.0 XNu

give a measurement uncertainty of 7.34% give a measurement uncertainty of 7.34% for the measured Nusselt numbersfor the measured Nusselt numbers

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AcknowledgementsAcknowledgements Manitoba HydroManitoba Hydro

Natural Sciences and Research Council Natural Sciences and Research Council f C d S Cf C d S Cof Canada (NSERC)of Canada (NSERC)

Canada Foundation for Innovation (CFI)Canada Foundation for Innovation (CFI)

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Thanks for your attentionThanks for your attention

Q i ?Q i ?Questions ? Questions ?

2007 ASME2007 ASME--JSME Thermal Engineering Summer Heat Transfer ConferenceJSME Thermal Engineering Summer Heat Transfer Conference