简介：Thispaperprovidesanumericalanalysismodelofunsteadyheattrans-ferinpiston-linersetofaninternalcombustionengine.Themodelsimulatestheun-steadyheattransferprocessamongthecombustionmixture,pistonset,lubricantfilm,linerandcoolantinawholeenginecycle,andcanpredictthetemperaturefluc-tuationanddistributiononpistoncrown,innersurfaceofliner,pistonringandthelubricantfilm.Acomputerprogramisdevelopedtocalculatetheunsteadyheattrans-ferprocessofpiston-linersysteminawater-cooleddieselengine.

简介：Effectsofexhaustgasrecirculation(EGR)onhomogeneouschargecombustionofn-heptanewasstudiedthroughsimulationandexperiment.Experimentswerecarriedoutinasinglecylinder,four-stroke,aircooledengineandasinglecylinder,two-stroke,watercooledengine.Inthefour-strokeengine,experimentsoftheeffectsofEGRwereexaminedusingheatedN2additionasasurrogateforexternalEGRandmodifyingenginetoincreaseinternalEGR.TheignitiontimingwassensitivetoEGRduetothermalandchemicaleffects.EGRorextraairisakeyfactorineliminatingknockduringmid-loadconditions.Forhigherloadoperationtheonlywaytoavoidknockistocontrolreactiontimingthroughtheuseofsparkignition.Experimentalandmodelingresultsfromthetwo-strokeengineshowthatauto-ignitioncanbeavoidedbyincreasingtheenginespeed.Thetwo-strokeengineexperimentsindicatethathighlevelsofinternalEGRcanenablesparkignitionatleanconditions.Athigherloadconditions,increasingtheenginespeedisaneffectivemethodtocontroltransitionfromhomogeneouschargecompressionignition(HCCI)operationtonon-HCCIoperationandsuccessfulsparkignitionofahighlydilutemixturecanavoidseriousknock.