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页数:17页
时间:2019-05-25
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1、Tutorial7.ModelingFlowThroughPorousMediaIntroductionManyindustrialapplicationsinvolvethemodelingofowthroughporousmedia,suchas_lters,catalystbeds,andpacking.Thistutorialillustrateshowtosetupandsolveaprobleminvolvinggasowthroughporousmedia.Theindustrialproblemsolvedhereinvolvesgasowthr
2、oughacatalyticconverter.Catalyticconvertersarecommonlyusedtopurifyemissionsfromgasolineanddieselenginesbyconvertingenvironmentallyhazardousexhaustemissionstoacceptablesubstances.Examplesofsuchemissionsincludecarbonmonoxide(CO),nitrogenoxides(NOx),andunburnedhydrocarbonfuels.Theseexha
3、ustgasemissionsareforcedthroughasubstrate,whichisaceramicstructurecoatedwithametalcatalystsuchasplatinumorpalladium.Thenatureoftheexhaustgasowisaveryimportantfactorindeterminingtheperformanceofthecatalyticconverter.Ofparticularimportanceisthepressuregradientandvelocitydistributionthr
4、oughthesubstrate.HenceCFDanalysisisusedtodesigne_cientcatalyticconverters:bymodelingtheexhaustgasow,thepressuredropandtheuniformityofowthroughthesubstratecanbedetermined.Inthistutorial,FLUENTisusedtomodeltheowofnitrogengasthroughacatalyticconvertergeometry,sothattheow_eldstructuremay
5、beanalyzed.Thistutorialdemonstrateshowtodothefollowing:_Setupaporouszoneforthesubstratewithappropriateresistances._Calculateasolutionforgasowthroughthecatalyticconverterusingthepressurebasedsolver._Plotpressureandvelocitydistributiononspeci_edplanesofthegeometry._Determinethepressure
6、dropthroughthesubstrateandthedegreeofnon-uniformityofowthroughcrosssectionsofthegeometryusingX-Yplotsandnumericalreports.PrerequisitesThistutorialassumesthatyouarefamiliarwiththemenustructureinFLUENTandthatyouhavecompletedTutorial1.Somestepsinthesetupandsolutionprocedurewillnotbeshow
7、nexplicitly.ProblemDescriptionThecatalyticconvertermodeledhereisshowninFigure7.1.Thenitrogenowsinthroughtheinletwithauniformvelocityof22.6m/s,passesthroughaceramicmonolithsubstratewithsquareshapedchannels,andthenexitsthroughtheoutlet.Whiletheowintheinletandoutletsectionsisturbulent,t
8、heowthrought
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