简介:Steadywatersurfaceprofileofgraduallyvariedflowcanbecalculatedusingei-therasteadyflowapproachoranunsteadyflowapproach.Thesteadyflowapproachrequiresit-erativeprocedureswhichmayhaveconvergenceproblemsunlessthestepsize1xislessthanamaximumvalue△x.Theunsteadyflowapproachbasedontheexplicitcharacteristicmethodhasastabilityproblemunless△xislessthan△x.Aseriesofnumericalexperimentswerecarriedoutandtheresultsoftwoapproachesarecompared.
简介:ThesupersonicductflowwithfixedbackpressuretostagnationpressureratioPb/P0underheatingisinvestigatedanalytically.A“FlowPatternDiagram”Whichconsistsofsixpatternzonesisdeveloped.BythisdiagramtheactualflowstateinsupersonicductflowsystemcanbedeterminedconvenientlywhenPb/Poandheatingintensityareknows.Itisimpossibleforflowwithheavyheatingtobecomesupersonic,eventhoughthepressureratioismuchsmallerthanthecriticalpressureratio,Basedontheanalogybetweenviscouseffectandheatingeffectathermaldragfactorhaseendefined.whichcanpredicttheflowpropertyvariationduetoheatingandtherelaiveimportanceofviscouseffectandheatingeffect.
简介:Quartz.NET是一个开源的调度框架,经历了2年多的开发终于发布了。该版本对应Java的Quartz1.6.2版本。它在作业调度方面提供了很好的灵活性而不牺牲简单性,能够为执行一个作业而创建简单的或复杂的调度。目前的版本支持数据库、集群、插件,支持cron-like表达式等等。
简介:Allexistingprotonexchangemembrane(PEM)fuelcellgasflowfieldshavebeendesignedonthebasisofsingle-phasegasflowdistribution.Thepresenceofliquidwaterintheflowcausesnon-uniformgasdistribution,leadingtopoorcellperformance.Thispaperdemonstratesthatagasflowrestrictor/distributor,asiscommonlyusedintwo-phaseflowtostabilizemultiphasetransportlinesandmultiphasereactors,canimprovethegasflowdistributionbysignificantlyreducinggasmal-distributioncausedbyeithernon-uniformwaterformationinparallelflowchannelsorflowinstabilityassociatedwithnegative-slopepressuredropcharacteristicoftwo-phasehorizontalflowsystems.
简介:Experimentswereconductedtoinvestigatetheeffectofimpellergeometryandtongueshapeontheflowfieldofcrossflowfans.Threeimpellers(Ⅰ,Ⅱ,Ⅲ)havingsameouterdiameter,butdifferentradiusratioandbladeangleswereemployedfortheinvestigation.Eachimpellerwastestedwithtwotongueshapes.Flowsurveywascarriedoutforeachimpellerandtongueshapeattwoflowcoefficients.andforeachflowcoefficientatdifferentcircumferentialpositions.Theflowistwo-dimensionalalongthebladespanexceptneartheshrouds.Thetotalpressuredevelopedbytheimpellersineachcaseisfoundtobemaximumatacircumferentialpositionofaround270°.Thetotalandstaticpressuresattheinletofimpellersaremoreorlesssameregardlessofimpellerandtonguegeometry,buttheyvaryconsiderablyatexitoftheimpellers.ImpellerⅢwithtongueT2developshighertotalpressureandefficiencywhereasimpellerⅡwithtongueT2developsminimumtotalpressure.HigherdiffusionandsmallervortexsizearethereasonsforbetterperformanceofimpellerⅢwithtongueT2。
简介:BasedonthePreissmannimplicitschemefortheone-dimensionalSaint-Venantequation,themathematicalmodelforone-dimensionalrivernetworksandcanalnetworkswasdevelopedandthekeyissuesonthemodelwereexpatiatedparticularlyinthisarticle.Thismodelappliesthemethodofthree-stepssolutionforchannel-junction-channeltosimulatetherivernetworks,andtheGausseliminationmethodwasusedtocalculatethesparsematrix.Thismodelwasappliedtosimulatethetree-typeirrigationcanalnetworks,complexloopedchannelnetworksandtheLowerColumbiaSloughnetworks.TheresultsofwaterlevelanddischargeagreewiththedatafromtheAdlulandfielddata.Themodelisprovedtoberobustforsimulatingunsteadyflowsinrivernetworkswithvariousdegreesofcomplexstructure.Thecalculatedresultsshowthatthismodelisusefulforengineeringapplicationsincomplicatedrivernetworks.Futureresearchwasrecommendedtofocusonsettingupecologicalnumericalmodelofwaterqualityinrivernetworksandcanalnetworks.