Abdul Hadi Bin Abd Majid

7/30/2019 Abdul Hadi Bin Abd Majid

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MO D E L L IN G A N D FA BRICA T IO N O F C Y L IN D E R H E A D FO R SIN G L E CY L IN D E R T W O ST RO K E E N G IN E

A BD U L H A D I BIN A BD MA J ID

A project report subm itted in part ial fulf i llmen t of the requirem entsfor the award of the Diploma o f Mechan ica l Engineer ing

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Facul ty o f M echanica l Engineer ingUniversit i Malaysia Pah ang

N O \T EMBER 2007


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ABSTRACT

Automotive technology is very important to people nowadays. To help them to movesomeplace to other place in short time. Automotive technology is very fast growingbecause of their needed in human life. The two stroke engine is reciprocating enginein which the piston takes over any valve functions in order to obtain power strokeeach revolution of the crankshaft. This involves the use of ports in the cylinder wallswhich are covered and uncovered by movements of piston. Two stroke engines areused for motorcycles, lawn mowers, chain saw and marine engine. Cylinder Head isone of the important parts in engine part. The purpose of The Cylinder Head to coverthe movement of piston from Bottom Dead Centre to Top Dead Centre and alsocombustion chamber in The C ylinder Head is very important in combustion process.

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ABSTRAK

Teknologi Au tomotif begitu penting dalam keh idupan seharian kita. lamenolong manusia bergerak dari satu tempat ke satu tempat y ang lain dalam m asayang singkat. Teknologi Autornotif mudah berkemba ng kerana kepentingannyadalam kehidupan manusia. Enjin dua lejang adalah engine perulangan dimana ombohmenganibil alih f'ungsi injap dimana untuk mengeka lkan lejang kuasa pada setiappusingan crankshaft . m i melibatkan kegunaan ruang dalam silinder dimana ditutupdan tidak dilindungi oleh pergerakan om boh. Enjin dua lejang digunakan untukmotosikal, gergaji rantai dan juga enjin kapal. Cy linder Head adalah salah satubahagian yang penting dalam bahagian engine. Kegu naan Cy linder Head a d a l a hmelindungi pergerakan omboh dari puncak tertinggi (TDC ) kepada puncak baw ah(B DC ) dan juga ruang pembakaran dalain cylinder head untuk proses pembakaran

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T A B L E O F C O N T E N T S

C H A P T E RITLE PAGEPROJECT TITLES UPE RVI S OR DE C L A RA T I ON

DE C L A RA T I ON DE DI C A T I ON i vA C K N O W L E D G E M E N T VABSTRACTA B S T R A K v i iT A B L E O F C O N T E N T S vi i iL I S T O F F I G UR E S x iL I S T OF T A B L E S x ivL I S T OF A PPE N DI C E S x v

I N T RODUC T I ON1.1 Introduct ion1.2 Problem Statement1.3 Object ive of Project1.4 Scope of The Project1.5 Project Organizat ion1.6 Author's Contribut ionVII'


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2ITERATURE REVIEW2.1 Introduction 52.2 Internal Combustion Engine 4

2.2.1lassification of Internal Com bustion Chamb er 52.3 Two-stroke engine 52.3.1 Characteristic of Two Stroke Engine 62.3.2 The Cylinder Head 7

2.4 Machining Process 82.4.1 CN C m achining 8 .2.4.2 Rapid prototyping 8

2.5Problems of Scavenging 1 32.5.1 Type of Scavenging 1 32.5.2 Scavenging Efficiency 1 42.5.3 Perfect Scavenging 1 42.5.4 Perfect Mixing 1 52.5.5 Short C ircuiting 1 5

2.6 Summary 1 6

3ETHODOLOGY73.1 Introduction 1 73.2 Overall Research Methodology 1 73.3 Engine Overhaul and Measuring 1 83.4 Three Dimensional CAD Drawing 1 93.5CFD Simulation 203.6 CNC M achining 3 23.7 Rapid Prototyping 3 3

3.7.1 Three Dim ensional Printing 3 33.7.2 Spectrum Z510 Specification 34

3.8 Summary 35


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4ESULT AND DISCUSSION 3 64.1 Introduction 3 64.2 Solid Work Result 3 64.3 Flow Analysis Result 3 7

4.3.1 Result For Inlet Mass Flow 0.03 3 74.3.2 Result For Inlet Mass Flow. 0.3 3 94.3.3 Result For Inlet Mass Flow 0.5 40

4.4 Dom ain Analysis 424.5 Fabrication Result 4 34.6 Conclusion 4 3

5ONCLUSION AND RECOMMENDATIONS 445.1 Introduction 445.2 Conclusion 445.3 Future Works 4 55.4 Summary 45

REFERENCES6APPENDICES


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L I ST O F F I G U R E S

F IG U R E N O . T I T L E P A G E

2 .1 The classification of internalcombustion engine 5

2 .2 Additive process 1 12 .3 The steps for investing casting that

used rapid prototyping w ax 1 22 .4 Theoretical scavenging process 1 53.1 Flowchar t 1 83 .2 The o riginal cylinder head 1 93.3 The ve rnier cal iper 1 93 .4 Three dimensional drawing of

cylinder head 2 03.5 Three dimensional drawing of

cylinder head 2 03 .6 Project wizard 2 13.7 Unit wizard 2 13 .8 Fluid type an d physical feature wizard 2 23 .9 Ana lysis type wizard 2 23.10 Roughness w izard 2 33.11 Fluid substances wizard 2 3

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3.12 Defau lt wall condition wizard 2 43.13 Initial and am bient conditions wizard 2 43.14 Result resolutions and geo metry

resolution wizard 2 53.15 Cosm os flow tree toolbar 2 63.16 Selection of boundary cond ition 2 63.17 The selection of boundary codition

for flow opening 263.18 Selection for second bo undary con dition 2 73.19 Selection of boundary condition for

pressure opening 2 73.20 Selection o f surface goal 2 83.21 Run toolbar 2 83.22 Solver monitor 2 93.23 Three dimen sional mesh toolbar 2 93.24 Three dimensional mesh 3 03.25 Cut plot toolbar 3 13.26 Surface plot toolbar 3 13.27 Flow trajectory toolbar 3 23.28 Simulation of cutting process using

masteream software 3 33.29 Spectrum Z5 10 3 43.30 Three dim ensional printing process 3 54.1 Three dimensional compu ter aided

design (CA D) drawing 36


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4.2 Solver result for inlet mass f low 0.03kg/s 3 74.3 Surface plot result for inlet mass

f low 0.03kg/s 3 84.4 Flow trajectory result for inlet mass

f low 0.3kg/s 3 84.5 Solver result for inlet mass f low 0.3kg/s 3 94.6 Surface plot result for inlet mass


f low 0.3kg/s 4 04.8 Solver result for inlet mass f low0.5kg/s 4 04.9 Surface plot result for inlet mass


f low 0.5kg/s 4 14.11 Domain analys is 4 24.12 Three dimensional pr inting result 43


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LIST OF TABLES

TABLE NO.ITLEAG E2.1he characteristic of rapid prototypingtechnologies

2 .2ypes of scavenging3 xiv


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C H A P T E R 1

I N T R O D U C T I O N

1.1ntroduct ionThis project title is modelling and fabrication of cylinder head for single

cylinder two stroke eng ines. First of all, two stroke engine is a simp le and lightengine that piston takes o ver valve function in operating cy cle. It is used forlightweight power units which can be employed in various attitudes as handheldpowe r tools [5].It is different from four strokes that ha d valves to control air flow inoperating cycle. Two-stroke engine was develop since 1876, in 1900 there wereengineers develop this engine with special em phasis on the various solution proposedfor improving gas exchan ge process [1]. The first two stroke engine for marine wasuse in 1905, this engine emp loyed uniflow scavenging with scavenge air valves incylinder head and exhaust ports in the lower part of the liner [1]. The characteristicof two-stroke cycle engine are one power stroke per revolution, scavenging withfresh charge, direct fuel injection, emissions and addition lubricating. Two-strokecycle can be used with both spark-ignition and comp ression-ignition. Comm onapplications are where weight low, small bulk, simple construction and high poweroutput are the prime consideration [1]. For the information, the largest and thesmallest internal comb ustion eng ines today are two-stroke cycle engine. There aresome ex ample of special applications, free-piston com pressor engines, gas producersand pulse-jet engine [1]. The cylinder head is m ade of cast iron or aluminium and itis strong to distribute the gas forces acting on the head as uniformly as possiblethrough the en gine block [2]. It is also contains spark plug for SI engine or fuelinjector for CI engine.


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1.2 Problem Statement

Mostly the cylinder head was made by casting process. This project is toproduce the cylinder head by using R apid Prototyping

1.3bjective of ProjectThe m ain object ive of this project is to fabricate a cy l inder h ead for s inglecylinder 30.5 cc two stroke spark-ignition (Si) engines.1.4cope of ProjectThere are four scop es in this project:i) Reverse engineering.ii ) Three dimension Computer Aided Design (CAD) modelling of originalproduct ion cyl inder hea d w hich i s des ign the or iginal cylinder head u s ing

CA D method that is Solid Work Software.iii) Simplify the design by just maintaining the key dimension such as clearanc e

volume, port dimension, and spark plug location in acco rdance of machiningcapabilities.

iv ) Fabricating the simplified model cylinder head using R apid Protolyping

1.4roject OrganizationCha pter 2: Find literature about the basic component of two stroke engines, operatingcycle of two stroke engine and advantage and problem of two stroke engines. Thischapter is about the theory of two stroke engine.


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Cha pter 3: First work in this chapter is drawing the original cylinder head and thens implifies complex geo metry of cyl inder head . Then s imulate the drawing us ingC osmo s F low Sof tware . Af te r t rans fe r d rawing to G-code us ing Mas te r CamSoftware then m achining process is begin. CN C Mill ing Mac hine is used for thisproce ss, ma chine s imulator calculate ma chining t ime an d mac hine running t il lcylinder head is produce.

Cha pter 4: The results provide detailed information on results and discussion on thisproject which are the pred iction of internal flow. Result also from machining proc essor rapid prototyping

Chap ter 5:Summa ries the resul t and prov ides conclus ions of the present w ork.Reco mme ndations for further works are also presented in this chapter.

1.5uthor's ContributionThree dimensional modell ing wa s developed using Computer Aided Design

(CAD ) Software. Introduce the s tep of in-cylinder flow an alysis was predicted byCo smos Flow Sof tware. Machining process for cylinder head is us ing C omputerNumerical Control (CNC) Mill ing o r R apid Prototyping.


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C H A P T E R 2

L I T E R A T U R E R E V I E W

2.1ntroduc t ionThis chapter concludes ab out general internal combust ion engine, two-stroke

engine characteris tic and ap plication then abo ut m achining process and also p roblemof scavenging.

2.2 n t e r n a l C o m b u s t io n En g i n e

The purpose of internal com bust ion engines product ion of mecha nical powe rf rom the ch em ical energy contained in the fuel . In internal com bustion engines, asdis t inc t f rom externa l com bus t ion engines , th is energy is re leased by burning oroxid izing the fuel ins ide the engine [2] . The w ork t ransfers w hich prov ide des i repow er output occur direct ly between f uel ai r mixture and com ponent of engine. Theinternal combu st ion en gines are spark-igni t ion (SI) and co m pression-rat io or dieselengine. Beau de R ochas out l ined the condi t ions under which maxim um ef ficiency inan in ternal combu st ion engine cou ld be ach ieved , there w ere the larges t poss ib lecyl inder vo lume w ith the m inimum boundary surface, the greatest possible workingspeed, the greatest possible expansion rat io and the greatest possible pressure at thebeginning of expansion [3] .


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2.2.1 Classificat ion of Internal Com bustion En gines

In ternal Com bust ion Engines

Four -SJoke Enginewo-Sfrolce EngineSI EnginePetro l Engineas EnrineCarbure ted Typenject ion T ypeIBatIery Igni t ionagnetd Ignit ion CI EngineDual Fue l l lvLi l t i fue l Div ided Chamber EnginengineP r e c h a m b e r S w i rl C h a m b e rW a t e ri r

Reciproca t ing (M ul t icy l inde r) R ec iproca t ing (Sing le cy l inde r) R o ta ry (W anke l )I I'V ' C y l inde r In - li ne Cy l inde r Opp osed C y l inde ri ng le R o t o r Tw i n R o t o rFigure 2.1 : The class if ica t ion of in ternal com bust ion engines [4]

2 .3 l 'wo-Stroke En gine

T w o - s t ro k e cy c l e l a ck s s e p a r a t e in t a k e a n d e x h a u s t s t r o k e s , a s ca v e n g i n gpum p i s r equi red to dr ive the f r esh charge in to cy l inder . In one o f the s imples t andm os t f r eq uen t ly u s ed t ypes o f t w o- s tr ok e eng i ne de s ign , t he bo t tom s u r f ac e o f t hepis ton in con junc t ion w i th tha t por tion o f c rankca se benea th each cy l inder i s used asthe scaven ging pum p [ I ].


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2.3.1 Ch aracterist ics of The T wo -Stroke Cycle Eng ine

i) One p ow er stroke per revo lution. Do ubling the numb er per uni t t ime relat iveto the four-s troke cycle increase powe r output per unit displacem ent volum e.T he ou t pu t o f t wo-s t rok e eng i nes r ange f r om 2 0 % t o 6 0 % above t hose o fequiva len t s ize four-st roke un i t . Doubl ing the num ber o f pow er s t rokes pe run i t t im e a lso ha lves the in te rva ls be tween com bust ion-genera ted pressureimpulses.

ii) Sc avenging w ith fresh charge. Inherent in the two-stroke cycle is the processof scavenging the burned gases f rom the eng ine cyl inder wi th f resh charge[1] . Un der n o rm al co n d i t io n , ab o u t 20% o f f r es h ch arg e t h a t en t e r s t h ecy l inder i s los t due to shor t c i rcui t ing to the exhau st . In ca rbure t ted sparkignit ion eng ines, the result in very high hyd rocarbon e m iss ions and po or fueleconom y comp ared with four-stroke engine.

iii) Emissions. The em iss ions cha racter i st ics of two-s t roke cycle eng ines a reobviously impo rtant and different from four-s troke eng ine. I t is requirem entst h a t mu s t b e me t dep en d o n th e a p p l i ca t io n an d a re es p ec i a l ly s tr i c t i nt ranspor ta t ion a rena . C onvent iona l two -s t roke spark ign i t ion en g ines wi thcarb u re t t o r wh ich a re s cav en g e d wi th a p rem ix ed fu e l a i r mix tu re h av eex t r em ely h ig h u n b u rn ed h ydro ca rb o n em is sio n s du e t o th e s ig n i fi c an tam ount of short ci rcui t ing fresh charge E l i .

iv ) Lubrication. Crankcase scavenged tw o-stroke engine cannot use convent ionalfour-s t roke we t sum p lubr icat ion sys tem s because large quant i t ies o f o i lwould be drawn in to com bust ion chamber .


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2.3.2 The Cylinder HeadThe two -stroke cylinder head either air or water cooled, certainly doesn't

look very exiting but its design has a large bearing on h ow w ell engine will run.Manufactures use various external shapes and cooling fin patterns but the mainrequiremen t is the cooling area is large enough to adequa tely cool the engine [3].W hat are more important are the shape of the com bustion chamber and the locationof spark plug location. Over the years, combustion chambers were design but only acouple are conducive to a reliable, high horse pow er engine. Researchers have foundthat the gases at the very outer limits of the combu stion cham ber called 'end gases'that self-ignite to cause detonation. Detonation occ urs when a po rtion of the fuel airmixture begins to burn spontaneously after normal ignition takes place. End gases areheated by surrounding metal of the piston crown and combustion chamber and alsoby the heat radiating from advancing spark-ignited flame. If the spark flame reachesthe outer edges of the combustion chamber quickly enough, these end gases will nothave time to h eat up suf ficiently to self-ignited and precipitate detonation. H erein liesthe key to preven t detonation-keep the end gases cool and reduce the time requiredfor the combustion flame to reach the end gases [3]. The most obvious step thatwould satisfy the second requirement is to make the com bustion chamber as sm all aspossible and then place the spark plug in the centre of the chamber. Naturallycombustion flame will reach the end gases in a sm all combustion space more quicklythan if chamber w ere twice as wide. A dditionally, a central plug reduces flame travelto minimum [3].

2.4 Fabrication Process Theory

2.4.1 CNC M achining

Comp uter Numerical Control (CNC ) M achine required G-code or M -code tooperating, please refer to appendix to see the list of codes.


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2.4.2 Rapid PrototypingRapid prototyping mostly used in the d evelopment stage of new product. It is

a technology wh ich considerably speeds the iterative product dev elopment process.Advantages of Rapid Prototyping:i) Reduce product development time and costii ) Get product to market fastiii) Enhance com munication between m arketing, engineering, manufacturing and

purchasingiv ) Present physical mod el at critical design reviewsV)erform functional prototype testing before comm itting to toolingvi)enerate precise production toolingDisadvantage of Rapid prototyping:i) Investment cost very highii ) Maintenance cost too highiii) Limitation on materials available

Application of Rapid Prototyping

i) Visualizationii ) Product verification (it is test for functionality)iii) Iterative product deve lopmentiv ) OptimizationV )abrication or manufacturevi )edical and b ioengineering


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Table 2 .1 : The character is tic of rapid proto lyping technologies-Suppl yp hase

-Process Layer

creationt echn iq ue

Phase change t ype Mater ials

Stereolitogra Liquid layer Photopolyinerizat io Photopolymersphy curing n (acrylates,

epoxies,Liquid colorable resins,

filled resins)

Solid-based Liquid layer Photopolymeriza t io Photopolymerscuring curing & n

mil l ingPolymers (ABS,

polyacrylate,Fused- Extrusion of Solidificat ion by e tc ) , wax , m eta lsdeposi t ion mel ted cool ing & ceram ics wi thmode l i ng p o l y m e r binderBall ist ic- Dropl e t Solidificat ion by Polymers , waxpartic le dep osition cooling

manufacturing


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Three- No phase change Ceramic ,dimens ional po lym e r & m e talPow de r

print ingLaye r o f

powders wi thpowder & binderbinder dropletdeposition

Select ive Laye r o f Laser driven Polym ers, m etalslaser pow de r sintering mel t ing powders wi th

sintering and sol idif icat ion binder , m etals,ce ramics & sand

wi th b inder

Solid Lam ina t e d - De pos i t ion o f No phase change Paper , polymersobjec t sheet m ater ia l

manufactur ing

C lassif icat ions of Rapid Prototyping are:

1 )ub t rac t ive (Rem oval of mate r ia l )Add i t ive (Adding of m ate r ia l )Vir tua l (Advanced com pute r base v isua liza t ion)Sub tractive processSub t rac t ive process use a comp ute r based pro to type technology to speed thep r o ce s s . If i t is f o r s h ap e v e r i f ic a t i o n , a p o l ym e r o r w ax i s u s e d b u t f o r a c t u a l


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appl icat io n , a ma chining pro cess s t i ll required. Essential technolo gies for subtract ivepro tOtyping are com pute r , in te rpre ta tion sof tware , man ufactur ing sof tware or C NCmachinery [4] .

Additive processThis p rocess bu i l t wo rkpiece or pa r ts in layer by layer which is s lice by s l ice andrequire elaborate software. The steps for this process are:

I )ain drawing f i le in CA D fi lei i) Com puter then constructs s l ice of a three dim ensional partsi i i) Slice analyzed and com piled to provide the rapid prototyping mach ineiv ) Setup the p roper una t tended and provide rough par t a f te r a few hoursv ) Fin ish ing opera t ion sand ing and pain t ing

- 1-IJ),I

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Figure 2.2: Ad dit ive process

Virtual process

Modelling and simulation of all aspects of prototype by a realisticvisua l iza tion . A l l a spec ts of des ign proce ss such as mech anica l des ign, k inem at ics ,


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dynam ics and controls but com plicated versions use virtual-reality headgear a ndgloves with approp riate sensors. Advantage of this process are instant rendering ofparts where the best design in shortest lead time of com plex product and process andallows the exotic, unconv entional design be prototyped, rapidly and cost-effectively.

Applications of Rapid Prototyping

i) Production of individual part. R apid Prototyping can be used to manufacturemarketable products directly especially involve the polymer parts. Patternused in investment casting also produced with R apid Prototyping techniqueshown in figure

flfl

Figure 2.3: The steps for investment casting that used rapid prototlyping w a x

ii) Rapid tooling. Typically used to describe a process w hich ei ther uses asR apid Prototyping m odel as a pattern to create a mold quickly or uses theRapid Prototyping process directly to fabricate a tool for a limited volume ofprototypes.


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25roblems of Scavenging

2.5.1 Type of Scaven ging

Scave nging is the operat ion of c lear ing the cyl inder of b urned gases andfilling it with fresh mixture-the comb ined intake and exhaust process. There are threeclassificatio n of scavenging (cross scavenged, loop scavenged, uniflow scaven ged).The problem o f scavenging is at there is a short circuiting directly betw een scave ngeports and exhaust ports in loop scavenged at 24 crank angles. Unif low scavenged isperfect scavenging.

Table 2.2: Types of scavenging

ross Scavengin^2I&

Uniflow Scavenging


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2.5.2 Scavenging Efficiency

The purity of charge can be m easure from the success of scavenging in thecylinder from com bustion of preceding cycle. It is controlled by shape o f comb ustioncham ber and scave ng ing ar rangem ent . Exper im en t t o de t e rmine the pur ity i srelatively simple, consisting only of analysis of gas sam ple taken d uring com pressions t r o k e .In Germ an technical literature the term sca venging efficiency has been widely used.It define as

- Vret - Vret2 . 1 )l l s cVret+Vres

It can be show n that the delivery ratio, scavenging and trapping e fficiency are relatedby the following equation

Crel flSCRdel= Iltrap2 . 2 )Sc aveng ing ef f iciency i s a term som ew hat s imi lar to pur i ty and exp resses theme asure of the success in clearing the cylinder of residual gases from the precedingcycle. Scave nging efficiency indicates to what extent the residual gases mea ns thatall the gases existing in the cylinder at the beginning of scavenging h ave sw ept out.

2.5.3 Perfect Sca veng ing

The fuel air mixture should remain separate from the residual produc ts ofcomb ustion w ith respect to both m ass and heat transfer during scavenging process[4]. Fresh charges are pu mped into the cylinder by the b lower through inlet port thenpush the products of combustion in cylinder out through exhaust port. How ever whe nsufficient fresh air has entered to fi l l the entire cylinder vo lume the flow abruptlychanges f rom one of prod ucts to one of a ir [4] . This ideal process wil l representperfect scavenging w ithout any short circuiting loss.

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Abdul Hadi Bin Abd Majid