直噴式柴油機(jī)噴霧混合過程的三維模擬研究.pdf

1、天津大學(xué)碩士學(xué)位論文直噴式柴油機(jī)噴霧混合過程的三維模擬研究姓名：周穎申請(qǐng)學(xué)位級(jí)別：碩士專業(yè)：動(dòng)力機(jī)械及工程指導(dǎo)教師：蘇萬(wàn)華20030101ABSTRACTSprayimpingementonwalls，whichappearsunavoidableincompactDIdieselengines，isallimportantphenomenathataffectsdieselcombustionrateandexhaustemissio

2、nsThewallfilm，resultingfromfueldeposition，mayproducenegativeeffects，suchaserdaantedsootformationandincreasedunburnthydrocarbonAsaconsequenceoftheexpandeduseofDIenginesinthelightdutyvehiclesandmorestringentlegislationonex

3、haustemissions，itiSnecessarytostudytheseprocessesinordertoachieveaunderstandingoftheireffectsonengineperformanceInthisstudythree—dimensionalCFDcalculationsofspraycharacteristicsina∞BUMPcombustionchamberarepresentedandeva

4、luatedItisdiscoveredthatduetothehi曲gastemperatureandpressureinthecylinderofsuperchargeddieselengine，whenthepistonisneartheTDCasshownintheconditionofthisstudy，above90％ofthedropletshaveevaporatedbeforetheyreachthewallAndth

5、ereisnoobviousdropletwallimpingementphenomenaSo，ThechoiceofimpingementmodelmaynotbeanimportantfactorinthesimulationItisalsoshownwhensprayreachesthewall，alargescaleswirlisformedbecauseoftheexistenceoftheBUMPThelocation，le

6、nghthscaleandintensityofswirlaredifferentaccordingtodifferent蝎ectionpressureThehighertheinjectionpressureis，theclosertheswirlistothewallandthelargerthelengthscaleis，buttheintensityissmallerViceversaBUMPcalls打ipimpingemen

7、tsprayfromwallandformsecondarywallsprayBecausethevelocityintheswirlcenterislowerthanthatintheperipheryoftheswirl，thefuelmixingrateinthecenteroftheswirlseemslowerthanthatattheperipheryisProperdesignofcombustionchamberaimi