王建昕+清华+缸内直喷发动机氧化模型预测(5)

3156F.Zhangetal./ProceedingsoftheCombustionInstitute33(2011)3151–3158

and6showthecomparisonbetweenexperimentalandmodelingresultsatU=1and2,respectively.Itindicatesthatthesimulationresultsofthepro-posedmechanismhaveagenerallygoodagreementwiththeexperimentaldata.However,thedi erencebetweensimulatedandexperimentaldatabecomeslargerinthehightemperatureregion.

4.SIenginesimulation

Inthisstudy,theBoostenginecyclesimulationsoftwareiscoupledwiththeCHEMKINprogramtosimulateSIengines.Boostisutilizedtosimu-latetheheatreleaseprocessofenginecombustion.AteachcalculationtimestepBoostprovidesthecorrespondingtemperatureTandpressureP,whicharede nedastheinputconditionsofCHEMKINtocalculatethevariationofeachspe-cies.Inthisway,thesimulationcanprovideamoreaccuratedescriptionoftheheatreleasepro-cessofSIengines.Thecoupledchemicalreactionkineticsisalsoabletocalculatethereactionvari-ationofeachspecies.

ingtheFouriertransformmethod,theabsorptionspectrum(intensity/wavelength)iscalculatedfromthedetectedinterferogram(inten-sity/time).Theindividualexhaustgascomponents

Table4

EQ491ienginesimulationparameters.Ignitionadvanceangle(°CA)26Enginespeed(r/min)2400EngineTorque(Nm)120Bore(mm)90.82Stroke(mm)

76.95Compressionratio

8.9Connectingrodlength(mm)

127

Table5

BoundaryandinitialconditionsofSIenginesimulation.Intakepressure0.1MPaIntaketemperature30°CExhaustpressure0.1MPaCylinderpressureat0.5MPaexhaustvalveopen

Cylindertemperatureat730°C

exhaustvalveopen

aredeterminedfromthespectrumbyusingrefer-encespectra(fromtheFTIRevaluationmethodpackages)andspeciallydevelopedmathematicalfunctionstominimizecrossinterference.ForHCHOcalibration,avaporizerwasembeddedintheFTIRwithaddingasolutionofformalde-hyde/H2O(0.01mol/L)tocalibratetheformalde-hydeemission.Forformaldehydemeasurementrangeof0–1000ppm,themeasurementaccuracyis3ppm.Thesamplingturnoverfrequencyis2Hz.Thevolumeofthesamplecellis200mL.Theopticalpathlengthis2m.Thewavenumberresolutionis0.5cmÀ1.Thesamplelinesandgascellareheatedto190°C(gascell185°C)topre-ventthecondensationandpolymerization.

Figure7givesthecalculatedcylinderpressurecurveofM30fuelusingthecombustionmodel,comparedwiththetestdata.Seenfromthe gure,thecylinderpressurecurveofthesimulatedresultsandexperimentaldataarebasicallythesame.

Figure8givesthecomputedformaldehydeemissionsofdi erentproportionalmethanol-gasolineblendedfuels.Thedual-zonecombustionmodelisadoptedinthecombustionphaseshown