降低汽油機(jī)有害排放物NOx的分層廢氣再循環(huán)的研究.pdf

1、天津大學(xué)博士學(xué)位論文降低汽油機(jī)有害排放物NOx的分層廢氣再循環(huán)的研究姓名：劉增勇申請學(xué)位級別：博士專業(yè)：動(dòng)力機(jī)械及工程指導(dǎo)教師：姚春德20031201ABSTRCTItisagreatchallengefortheautomotiveindustrydevelopmenttomeettherequirementformoreandmorestringentenvironmentpollutionregulationsandseveres

2、hortageofpetroleum0ilAsNOxemissionfromSIengineisoneofmaincomponentstofoITnopticalchemicalsmoke，itisveryimportanttorestrictNOxemissionsIntheexistingmethods，EGRisrelativelyeffectivetechnologynotonlyteducetheemissionofNOxbu

3、talsotosaverueIconsumptionatpartIoadTheconventionalEGRdirectlyenteringintakemanifoldislimitedbycycle’bv，cyclevariationandfurtherdecreasingNOxemission，iflargeratioofEGRleadstoengine，whichwillincrcasefuelconsumptionandC0an

4、dHCemissionsHowever，thestratifiedEGRwithdecreasingofthecyclebv—cyclevariationandincreasingoftheratioofEGR，notonlyreducestheemissionofNOxfurtherandthepumpinglOSSatpart10adbutalsoimprovesthefueleconomvSothestratifiedEGRist

5、akenasaimportantmeansteducetheemissionofNOxThestudyfocusesonthetechniqueofstratifiedEGR，whichconsistsofthemechanismofstratification，theforillofstratificationandtheinfluenceonmixtureforill，combustionprocessandengineperfor

6、manceundertheconditionofstratificationTheresearchselectsafourcylinderSIenginewithfourvalvesforeachcylinder，whichproducesstrongtumblemotionanddevisesspecialstratifiedconfigurationofEGRneexhaustgasisleadedtosingleintakepor

7、tbytheguidedjetandachievesstratificationwithfreshmixturebyusingtumblemotionoftheengineinthecylinderThedifferentEGRmodesarerealizedbychangingthelocationoftheguidedietTheresultofthetestdemonstratesthatthemodesofEGRhaveobvi

8、ousinfluenceonengineperformance，Atpartload，thejelbythesideofintakeportattainsbettereconomythanconventionalmodewiththefuelconsumptionreductionbv41％SimultaneouslyNOxandCOaswelIasHCreducesmostlywiththeincreasingofEGRratioTh

9、ewholeEGRratioswiththemodethatthejetlocatesbythesideofportarelargerthanthatoftheconventionalmodeandthemaximumratieachesto43％AttheconditionofsameEGRratio，cylinderpressureoftheside@tmodeisbiggerthanthatofconventionalmodean

10、dtheformerdoesn’trequirecooledEGRByusingthesidejetmode，EGRneedsappropriateignitiontimingUsingtheadvanced1asermeasuremethodandthevisualizationtechnologyofin—cylindergasflowunderthedifferentEGRmodesinvestigatedincylinderga

11、sflowandtheconcentrationdistributionoftheexhaustgasTheresultsshowthataddingEGRthrou曲thesidejetcanmaketheexhaustgasstratifiedincylinderwithfreshchargeThestratifiedphenomenonisobviousatthestartpointoftheintakecycle，andthee

12、xhaustgasandthepre—mixedgasdistributeoneachsideincylinderoftheenginerespectivelywhichalmost1aststotheendofcompressionstrokeAndneartheendofthecompressstroke，theexhaustgasmixeswiththefreshchargegraduallyhoweverthedistribut

13、ionoftheexhaustgasandthefreshchargeisheterogeneousasawholeThetumblingflowsstratifyofthesidejetEGRismoreobviouslyasthespeedoftheengineincreasesBasedontheexhaustgasstratifiedruleandtheresultsobtainedfromthebenchtestsandthe