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1、上海交通大学硕士学位论文ABSTRACTpredictedbythesethreemodelsishigherthanthatoftheexperimentalresults.Asisshowninmanycases,thek-ωmodelusuallyyieldsmoreacceptablepredictioninthenearwallregionthank-εmodel.Inareaswheretheeffectofspacergridsisnotprominentthetemperaturedistributionderivedfromk-ωSSTm
2、odelistheclosesttoexperimentaldata.However,inthevicinityofspacergrids,k-ωSSTmodelandrealizablek-εmodelareunabletoprovideaccuratepredictionduetomodificationofturbulentviscositywhichrestrainsthegenerationofturbulentkineticenergy.Judgingfromtheoverallperformance,thek-ωSSTmodelisadvis
3、edtoperformthesimulationandmoresuitableturbulencemodelsshouldbedevelopedinthefuturetoyieldmoreaccurateresults.Basedontheevaluationofturbulencemodel,athree-dimensionalnumericalinvestigationisconductedusingthek-ωSSTmodeltoexploretheeffectofwireonthefuelonthewallshearstressandtempera
4、turedistributionofexternalfuelrodsurface,aswellasontheflowandheattransferofsupercriticalwaterinSupercriticalWater-cooledReactor-FuelQualificationTest(SCWR-FQT)activechannels.Thecalculationresultsshowthattheflowdirectionofsupercriticalwaterisguidedbythewrappedwireandthatthedistribu
5、tionsofstreamlines,velocity,pressure,turbulentkineticenergyandtemperatureoffluidonthecross-sectionofflowchannelspresentperiodicalchangesalongwiththerotationofwire.第IV页万方数据上海交通大学硕士学位论文ABSTRACTThewirespacersenhancemixingandmakethedistributionoffluidtemperatureandvelocityonthecross-s
6、ectionmoreuniform.However,inSCWR-FQTactivechannels,wallheatfluxishighintheregionwherefluidtemperatureapproachesthepseudo-criticaltemperature,whichmayinducetheoccurrenceofheattransferdeterioration.Additionally,duetothenarrowsurfaceofcontactbetweenthefuelrodandthewire,itishighlyposs
7、ibleforfluidtostagnateintheseregions,whichvitiatesheattransferbetweenfluidandrod.Thesephenomenadeservespecialattentionintheprocessofwire-wrappedfuelassemblydesign.Finally,tounderstandtheeffectofpitch-to-diameterratioonheattransferin4-rodbundleswithintheSCWR,anumericalcalculationis
8、performedwithk-ωSSTmodel.Theresul
