I摘要大气污浊源解析表明,机动车已经成为重点城市地区空气污浊的主要来源,世界主要国家和地区相继加严放出法规来降低机动车所造成的环境污浊问题。近年来，伴随人们生活水平的提高，越来越多的人出行选择自驾的方式，对拉动经济增长起到了固定的作用，在许多领域上，也不乏有柴油机的身影，如农用机械、工程机械、船舶机械等，为人们的生活带来了很多好处。但也因此机动车放出的微粒物和氮氧化物对环境造成的污浊越来越严重。所以知晓车辆排出气体微粒物的放出分散特征显得尤为重要。本文采取在GAMBIT里建造不同管径和不同排气方向的排气管二维模板而且归类网格，然后导入FLUENT，结合自己所学知识并对其实施仿真解析的措施，探索车辆排气管在不同设计参数下尾部微粒物放出分散特征。结论：当排气管的离地高度和倾角相同时，排气管管径的不同会影响微粒物的分散。当排气管管径越大时，微粒物的流速越大，其分散范围也会变大。排气管的倾斜角度也会影响微粒物的分散。当排气管上倾时，与水平排气相比，排出气体会向上放出，流场还可能伴随提升，让较多的微粒物飘在空气里，所以PM2.5的停留时间会提升；排气管下倾时，与水平放出相比，流场偏低，容易造成PM2.5的积聚。同一管径下，伴随排气管离地高度的增大，排出气体的分散范围也会随之变大。关键字：微粒物，分散，FLUENT，排气管IIIAbstractTheanalysisofairpollutionsourcesshowsthatmotorvehicleshavebecomethemainsourceofairpollutioninkeyurbanareas.Majorcountriesandregionsintheworldhavetightenedemissionregulationstoreducetheenvironmentalpollutioncausedbymotorvehicles.Inrecentyears,withtheimprovementofpeople'slivingstandards,moreandmorepeoplechoosethewayofselfdriving,whichplaysacertainroleinstimulatingeconomicgrowth.Inmanyfields,therearealsodieselengines,suchasagriculturalmachinery,engineeringmachinery,marinemachinery,etc.,whichbringalotofbenefitstopeople'slife.However,thepollutionofparticulatematterandnitrogenoxidesfrommotorvehiclesisbecomingmoreandmoreserious.Therefore,itisparticularlyimportanttounderstandtheemissiondiffusioncharacteristicsofvehicleexhaustparticles.Inthispaper,thetwo-dimensionalmodelsofexhaustpipeswithdifferentdiametersandexhaustdirectionsareestablishedingambitandmeshed,andthenimportedintofluent,combinedwiththeirownknowledgeandsimulationanalysismethod,tostudytheemissionanddiffusioncharacteristicsofparticulatematterinthetailofautomobileexhaustpipeunderdifferentdesignparameters.Conclusion:whentheheightandinclinationoftheexhaustpipearethesame,thedifferentdiameteroftheexhaustpipewillaffectthediffusionofparticulatematter.Whenthediameteroftheexhaustpipeislarger,thevelocityofparticlesislargerandthediffusionrangeislarger.ThedirectionofexhaustpipealsoaffectsthediffusionofPM2.5.Whenthetailgaspipeinclinesupward,comparedwiththehorizontaldirection,thetailgasisdischargedupward,andtheflowfieldishigher,whichmakestheparticlessuspendedintheairforalongtime,sotheresidencetimeofPM2.5intheairbecomeslonger;Whentheexhaustpipeinclinesdownward,comparedwiththehorizontaldirection,theflowfieldislower,whichmakesPM2.5easytosettleandaccumulate.Underthesamepipediameter,withtheincreaseoftheheightoftheexhaustpipeabovetheground,thediffusionrangeoftheexhaustgaswillbecomelarger.IIIIIKeywords:Particulatematter,diffusion,fluent,exhaustpipe目录1绪论.................................................................61.1探索背景.......................................................61.2探索意义和目的.................................................61.3国内外探索现状.................................................71.3.1国内探索现状.....................
