資源描述:
《論文格式標(biāo)準(zhǔn)》由會員上傳分享,免費在線閱讀,更多相關(guān)內(nèi)容在工程資料-天天文庫。
1、均質(zhì)充量壓縮著火(HCCI)燃燒,作為一種能冇效實現(xiàn)高效低污染的燃燒方式,能夠使發(fā)動機同時保持較高的燃油經(jīng)濟性和動力性能,而H.能有效降低發(fā)動機的NC和碳煙排放。此外HCCI燃燒的一?個顯著特點是燃料的著火時刻和燃燒過程主要受化學(xué)動力學(xué)控制,基于這個特點,發(fā)動機結(jié)構(gòu)參數(shù)和工況的改變將顯著地影響著HCCI發(fā)動機的著火和燃燒過程。本文以新型發(fā)動機代用燃料二甲瞇(DME)為例,對HCCI發(fā)動機燃用DME的著火和燃燒過程進行了研究。研究采川由美國LawrenceLivermore國家實驗室提出的DME詳細(xì)化學(xué)動力學(xué)反應(yīng)機理及其開發(fā)的HCT化學(xué)動力學(xué)程序,KDME的詳細(xì)氧化機理包括
2、399個基元反應(yīng),涉及79個組分。為考慮壁面?zhèn)鳠岬挠绊?,在HCT程序中增加了壁面?zhèn)鳠嶙幽P?。采川該方法研究了壓縮比、燃空當(dāng)量比、進氣充量加熱、發(fā)動機轉(zhuǎn)速、EGR和燃料添加劑等因素對HCCI著火和燃燒的影響。結(jié)果表明,DME的HCCI燃燒過程有明顯的低溫反應(yīng)放熱和高溫反應(yīng)放熱兩階段;增大壓縮比、燃空當(dāng)量比、提高進氣充量溫度、添加H2O2、比、CO使著火提前;提高發(fā)動機轉(zhuǎn)速、采用冷卻EGR、添加CH4>CH3OH使著火滯后。空一行關(guān)鍵字:均質(zhì)充量床縮著火,化學(xué)動力學(xué),數(shù)值模擬,二甲腿EGR,燃料添加劑摘耍正文五號宋體,首行縮進二個字,字?jǐn)?shù)300—500字,單倍行距。小四號黑體五
3、號宋體,逗號分開,最后一個關(guān)鍵字后面無標(biāo)點符號。NUMERICALSIMULATIONOFHOMOGENEOUSCHARGECOMPRESSIONIGNITIONCOMBUSTIONFUELEDWITHDIMETHYLETHER四號TimesNewRoman居中加黑ABSTRACT三號TimesNewRoman居中加黑,一律用大寫字母,上下各空、—行??找恍袕S五號TimesNewRoman,首行縮進,單倍行距。HCCI(HomogenousChargeCompressionIgnition)combustionhasadvantages.......--/ihtermsof
4、efficiencyandreducedemission.HCCIcombustioncannotonlyensureboththehigheconomicanddynamicqualityoftheengine,butalsoefficientlyreducetheN0xandsmokeemission.Moreover,oneoftheremarkablecharacteristicsofHCCIcombustionisthattheignitionandcombustionprocessarecontrolledbythechemicalkinetics,sotheH
5、CCIignitiontimecanvarysignificantlywiththechangesofengineconfigurationparametersandoperatingconditions?InthisworknumericalschemefortheignitionandcombustionprocessofDMEhomogeneouschargecompressionignitionisstudied.ThedetailedreactionmechanismofDMEproposedbyAmericanLawrenceLivermoreNationalL
6、aboratory(LLNL)andtheHCTchemicalkineticscodedevelopedbyLLNLareusedtoinvestigatetheignitionandcombustionprocessesofanHCCIenginefueledwithDME.ThenewkineticmechanismforDMEconsistsof79speciesand399reactions.Toconsidertheeffectofwallheattransfer,awallheattransfermodelisaddedintotheHCTcode.Bythi
7、smethod,theeffectsofthecompressionratio,thefuel-airequivalenceratio,theintakechargeheating,theenginespeed,EGRandfueladditiveontheHCCIignitionandcombustionarestudied.TheresultsshowthattheHCCIcombustionfueledwithDMEconsistsofalowtemperaturereactionheatreleaseper