1、mv.- -,-4.! * 0 j. 1.1. * * o .*-I* -* A- f* 1-aDesign and Simulation ofFour-Stroke EnginesAlso by GordonP Blair: Designand Simulation ofTwo-Stroke Engines (OrderNo. R-161) For more information or to-order this book, contact SAE at 400 Commonwealth Drive, Warrendale,PA 15096-0001; (724)7764970; fax(
2、724)776-0790; e-mail: publicationssae.org; web site: www.sae.org/BOOKSTORE.Design and Simulation ofFour-Stroke Engines Gordon P. Blair *AM INTfERNAIONAL Society ofAutomotive Engineers, Inc. Warrendale, Pa.Copyright 1999 Society ofAutomotive Engineers, Inc. 400 Commonwealth Drive Warrendale, PA 15096
3、-0001 U.S.A. Phone: (724)776-4841 Fax: (724)776-5760 E-mail: publicationssae.org http:/www.sae.org ISBN 0-7680-0440-3 All rights reserved. Printed in the United States ofAmerica Permission to photocopy for internal or personal use, or the internal or personal use ofspecific clients, is granted bySAE
4、 for libraries and other users registered with the Copyright Clearance Center (CCC), provided that the base fee of$.50 perpage is paid directly to CCC, 222 Rosewood Dr., Danvers,MA 01923. Special requests shouldbe addressed to theSAE Publications Group. 0-7680-0440-3/99-$.50. SAE OrderNo. R-186 Libr
5、ary ofCongress Cataloging-in-Publication Data Blair, Gordon P. Design and simulation offour-stroke engines / Gordon P. Blair. p. cm. Includes bibliographical references and index. ISBN 0-7680-0440-3 1. Four-stroke cycle engines-Design and construction I. Title. TJ790.B577 1999 621.43-dc2l 99-27316 C
6、IPThe Last Mulled Toast A Grand Prix race is very rough, the goings fast, the pace is tough. The four-stroke rules the world ofcars, in bikes its two-strokes that are the stars. Now, why is this youd have to ask? The rulemakers you can take to task. For the intake air neverneeds to question, “Is thi
7、s the right bellmouth formy ingestion?“ The designer ofboth must surely know, or else his engines will all be slow, unsteady gas dynamic trapping by right and left waves overlapping. To model an engine is algebraic simple. You sit on the gas like a veritable pimple, solving the maths the waves to tr
8、ack from valve to bellmouth in the intake stack. At the inlet valve you scan induction, count the air thats passedby suction andjust as the valve would shut the door, you get awave toramhome more. In the exhaust its furnace hot, for the modeller tis a tropic spot. Exhaust waves reflect but do thejob
9、 ofsucking out the burned gas slob. Some time ago I wrote two tomes on two-strokes, including poems. It seemed only fair to tell those with cars that black-art tuning is best kept for bars. This book informs the four-stroke tuner what I wish Iknew those decades sooner, as Brian Steenson followedAgos
10、tini withmy exhaust onMickMooneys Seeley. The pens both strokes havenow been told. My writ is run, Im pensioned old. While I may be ancient and time is shrinking, onlyDei voluntas can stopme thinking. Gordon Blair 1 November 1998 vForeword Since 1990,1 have writtentwobooks on the design and simulati
11、on oftwo-stroke engines. Notmany in the four-stroke engine industry will read suchbooks on the assumption that they are not relevant to them. I will not dwell on this issue as I have already dedicated a couple of stanzas to this very point, on the previous page. Hence, when I came to write this Fore
12、word, and reread what I had set down in those previous books, I realized that much ofwhat was written there for the two-stroke enthusiast was equally applicable to the reader ofthis book. So, ifmuchofthis reads like theForeword inmyprevious books, Icanonlyrespondby saying that I know only onewayofte
13、aching this subject. So, ifyouhave already absorbed that, then pass on. This book is intended to be an information source for those who are, or wish to be, involved inthe design offour-stroke engines. More particularly, thebook is adesign aid in the areas ofgas dynamics, fluid mechanics, thermodynam
14、ics, and combustion. To stop you from instantly putting the bookdown in terror at this point, rest assured that the whole purpose of this book is to provide design assistance with the actual mechanical design ofan engine in which the gas dynamics, fluid mechanics, thermodynamics, and combustion have
15、 been opti- mized so as to provide the required performance characteristics ofpower, or torque, or fuel consumption, ornoise emission. Therefore, thebook will attempt to explain the intricacies of, for example, intake ramming, and then provide you with empiricisms to assist you with the mechanical d
16、esign to produce, to use the same example, better intake ramming in any engine design.Muchoftheengine simulation, withwhich Iwasinvolved atQUB overthe lasttwenty- five years, and towhich I have appliedmyselfevenmore thoroughly in the three years since I formally retired frommy alma mater, hasbecome
17、so complex, orrequires such detailed input data, that the operator cannot see the design wood for the data trees. As a consequence, I wound this empiricism into visual software to guideme toward amore relevant input data set before applying it into an engine simulationcomputermodel. Quite often, the
18、 simulation con- firms that the empiricism, containing as it does the distilled experience ofaworking lifetime, was adequate in the first place. However, sometimes it does notand thatbecomes the starting point for a more thorough design and comprehension process by simulation. You will find many exa
19、mples ofthat within this book. However, even that starting point is closer to a final, optimized answer than itwouldhave been ifmere guesses hadbeen the initial gambit for the selection ofinput data to the engine simulation. The opening ofthe book deals with the fundamentals ofengine design and deve
20、lopment, rangingfrommechanicalprinciples, toengine testingandthethermodynamics ofengine cycles. To some it will read like the undergraduate text they once had; to undergraduates it will read viiDesign andSimulation ofFour-StrokeEngines like a tutorial by some pedantic professor, and to thosewho had
21、no such formal education it will provide the thermodynamic backdrop they never had, butwhich they will need to follow the logic ofthe design and development ofthe four-stroke engine. It reminds you all, expert and novice alike, ofthe basics ofthe scene inwhichyouwish to operate. The acquisition ofa
22、fundamental understanding ofunsteady gas dynamics is the firstmajor step to becoming a competent engine designer. Hence, this book contains a major section dealing with that subject. It is little different than that within the more recent book on two- stroke engines*, although it is updated and exte
23、nded with, it is hoped, all, typographical and theoretical errors removed. The fundamental theory ofunsteady gas dynamics is the same for two-stroke and four-stroke engines, but I repeatmyselfas yet another stanzahas already dealt with that. Nevertheless, without abasic understandingofunsteady gas d
24、ynamics, the myster- ies ofintake and exhaust tuning will remainjust that. The “flowing ofcylinderheads“ is awayoflife formanydevelopers ofhigh-performance engines.As with all technologies, there is a right, andawrong,wayofgoing about it. I explain the onlyway to acquire thedischarge coefficients of
25、flowwhich willbe meaningful ifthey are also required to be accurately applied with an engine simulation model. The discussion ofcombustion follows apragmatic approach, as distinct from one steeped in the chemistry ofthe subject. It provides data on the burn characteristics ofa considerable range ofa
26、ctual engines, spark-ignitionandcompression-ignition, inamannerwhich gives real data input for thosewho wish to simulate awide variety ofpower units with truly representa- tive combustion characteristics. The discussion on noise emission illustrates the point that actual silencers, intake, and exhau
27、st, canbe designedby simulationso thatthetrade-offinnoise emissionandperformance characteristics canbe thoroughly executedby the modeling ofthe entire engine togetherwith its mufflers. Italsomakes thepointthatthe traditional empiricism,which isbased in acoustics, has a useful role to play in the des
28、ign process as long as you do not believe implicitly in its predictions. The majority ofthebook is devoted to the designofthe spark-ignition engine, but there is also comprehensive treatment ofthe diesel or compression-ignition engine. The totality ofthe book isjust as applicable to the design ofthe
29、 diesel as it is to the gasoline engine, for the only real difference between them is the methodology ofthe combustion process. Much like thisForeword, the openingparagraphs ofmanyofthe chapters are very similar to those in the book on two-stroke engines. I suppose it is a simple statement, albeit a
30、 truism nevertheless, buthaving figured outa logicalway to introduceyou to the fundamentals ofany given topic, and as those fimdamentals donotchangejustbecause Iamwritingaboutthe four- stroke engine, I decided that I would only sing the song badly if I attempted to change the lyrics. Ihavehadthe ine
31、stimable privilegeofbeingaround atprecisely thatpoint inhistorywhen it became possible to unravel the technology ofengine design from the unscientific black art which had surrounded it since the time ofOtto, Diesel, and Clerk. That unraveling occurred because the digital computer permitted the progr
32、amming of the fundamental unsteady gas- dynamic theory which has been in existence since the time ofRayleigh, Kelvin, Stokes, and *See Chapter 1, Ref. 1.9 viiiForeword Taylor. Forme, that interestwas stimulatedby a fascination withhigh-performance engines in general, motorcycles in particular, and t
33、wo-stroke engines evenmore particularly. It is a fasci- nation that has never faded. Themarriage ofthesetwo interests, computers andracing engines, hasproduced thisbook and the material within it. For those in this world who are of a like mind, this book should prove to be useful. Gordon P. Blair 23
34、 October 1998 ixAcknowledgements As I explained in the Foreword, this is the third book I have written, but the acknowledgements in those earlierbooks are still pertinent. The individuals who have influ- encedmy life andwork are still the very same people, so what else can I say. The first acknowled
35、gement is to those who enthused me duringmy school days on the subject ofintemal combustion engines in general, and motorcycles in particular. They setme on the road to athoroughly satisfyingresearch careerwhichhasneverseen a hintofboredom. Thetwo individuals weremy father,whohad enthusiasticallyown
36、edmanymotorcycles in his youth, and Mr. Rupert Cameron, who had owned but one and had ridden it everywhere-a 1925 350 cc Rover. Ofthe two, RupertCameronwas the greater influence, forhewas awalk- ing library oftheGrandPrixracesofthetwentiesand thirtiesandwouldtalkofengine design, and engineering desi
37、gn, in the mostknowledgeable manner. Hewas actually the seniornaval architect at Harland and Wolffs shipyard in Belfast and was responsible for the design of some ofthe grandest liners ever to sail the oceans. My father and Mr. Cameron talked frequently oftwo fellow Ulstermen, Joe Craig and Walter R
38、usk. They are both shown in the photograph in Plate 1.0, Joe Craig standing to the right and Walter Rusk astride the motorcycle. Walter Rusk isjust about to start in the Ulster Grand Prixof1935 on aworks Norton; he crashedonthesecondlapwhile leading. The Ulster Grand Prixwas the Grand Prix dEurope t
39、hat year, so itwas an evenbiggershow thannormal in a province where 10% ofthe entire population were known, and still areknown, to turnup to watch a motorcycle race. Local media coverage ensures that racers, tuners, and engineers are householdnames. Joe Craigwas the ChiefEngineerofNortonMotorcycles
40、from the early 1930s to the 1950s and he was responsible for the development ofthe single-cylinder 500 cc ManxNorton throughout that period.Acutawaydrawing ofthe 1959 version ofthis engine is shown in Plate 1.2 andyou can see its heredity etched in the lines ofthe 1935 engine in Plate 1.0. Joe Craig
41、 came from Ballymena in Co. Antrim. He designed and developed that same engine from 31 bhp in 1931 to 53 bhp in 1953, and as a schoolboy I listened to those tales and thoughthow grand itwouldbe toknow somuch abouttuning engines as to be able to do that. WalterRuskcame fromnearby inWhitehead inCo.Ant
42、rimandwenttomyalmamater,Larne Grammar School. He was one of the top-bracket racers of the 1930s. He was killed while flying in the RoyalAirForceand I lookedup at hisname, written ingoldonthe RollofHonor for WorldWar II, at school assembly every morning. These two people weremy schoolboy heroes,butof
43、thetwo itwasJoe Craig,andhis genius atenginetuning,who exertedthe greater fascination. I have to acknowledge that this bookwould notbe written today but for the good fortune that brought Dr. Frank Wallace (Professor at Bath University since 1965 andnow retired) to Belfast in theveryyear that Iwished
44、 todopostgraduate research atTheQueensUniversity of xiDesign andSimulation ofFour-StrokeEngines Plate 1.0 WalterRuskandJoe Craig at the 1935 Ulster GrandPrix. (Courtesy ofNorman Windrum) Belfast (QUB). At that time, Frank Wallace was one ofperhaps a dozen people in the world who comprehended unstead
45、y gas dynamics, whichwas the subject area I alreadyknew I had to understand ifIwas evertobe acompetent engine designer. However, FrankWallace taught me something else as well by example, and that is academic integrity. Others willjudgehow well I learned either lesson. Professor Sir Bernard Crossland
46、 deserves a special mention, for he became the Head of the Department ofMechanical Engineering atQUB in the same year I started as a doctoral research student. His drive and initiative set the tone for the engineering research that has continued at QUB until the present day. I emphasize the word “en
47、gineering“ because he instilled in me, and a complete generation, that real “know-how“ comes from using the best theoretical science available, at the same time as conducting related experiments ofaproduct design, manufacture, build, and test nature. That he became, in later years, a Fellow ofthe Ro
48、yal Society, a Fellow ofthe RoyalAcademy ofEngineering, and a President ofthe Institu- tion ofMechanical Engineers, andwas knighted, seems no more thanjustice. xiiAcknowledgements Ihavebeenvery fortunate inmyearlyeducation tohavehadteachers ofmathematicswho taughtme the subjectnot onlywith enthusias
49、m but,muchmore importantly, from the pointof view ofapplication. I refer particularly to Mr. T. H. Benson atLameGrammar School and to Mr. Scott duringmy undergraduate studies atThe Queens University ofBelfast. They gave me a lifelong interest in the application ofmathematics to problem solving which has never faded. The next acknowledgement is to thosewho conceived andproduced the Macintosh com- puter. Without thatmachine, onwhich Ihavetyped this entire manuscript, drawn every figure that isnotfromSAE archives, anddeveloped allofthe simulation software, therewouldbeno bo
