Author/Authors :
U.Rohde، نويسنده , , T.H?hne، نويسنده , , S.Kliem، نويسنده , , B.Hemstr?m، نويسنده , , Stephan Scheuerer، نويسنده , , T.Toppila، نويسنده , , A.Aszodi، نويسنده , , I.Boros، نويسنده , , I.Farkas، نويسنده , , P.Mühlbauer، نويسنده , , L.Vyskocil، نويسنده , , J.Klepac، نويسنده , , J.Remis، نويسنده , , T.Dury، نويسنده ,
Abstract :
TheEUprojectFLOMIX-Rwasaimedatdescribingthemixingphenomenarelevantforbothsafetyanalysis,particularlyinsteamlinebreakandborondilutionscenarios,andmixingphenomenaofinterestforeconomicaloperationandthestructuralintegrity.
Thisreportwillfocusonthecomputationalfluiddynamics(CFD)codevalidation.Bestpracticeguidelines(BPG)wereappliedinallCFDworkwhenchoosingcomputationalgrid,timestep,turbulencemodels,modellingofinternalgeometry,boundaryconditions,numericalschemesandconvergencecriteria.ThestrategyofcodevalidationbasedontheBPGandamatrixofCFDcodevalidationcalculationshavebeenelaborated.CFDcalculationshavebeenaccomplishedforselectedexperimentswithtwodifferentCFDcodes(CFX,FLUENT).Thematrixofbenchmarkcasescontainsslugmixingtestssimulatingthestart-upofthefirstmaincirculationpumpwhichhavebeenperformedwiththree1:5scaledfacilities:theRossendorfcoolantmixingmodelROCOM,theVattenfalltestfacilityandametalmock-upofaVVER-1000typereactor.Beforestudyingmixingintransients,ROCOMtestcaseswithsteady-stateflowconditionswereconsidered.Consideringbuoyancydrivenmixing,experimentalresultsonmixingoffluidswithdensitydifferencesobtainedatROCOMandtheFORTUMPTStestfacilitywerecomparedwithcalculations.Methodsforaquantitativecomparisonbetweenthecalculatedandmeasuredmixingscalardistributionshavebeenelaboratedandapplied.Basedonthe“bestpracticeCFDsolutions”,conclusionsontheapplicabilityofCFDforturbulentmixingproblemsinPWRweredrawnandrecommendationsonCFDmodellingweregiven.TheresultsoftheCFDcalculationsaremostlyin-betweentheuncertaintybandsoftheexperiments.Althoughnofullygrid-independentnumericalsolutionscouldbeobtained,itcanbeconcludedaboutthesuitabilityofapplyingCFDmethodsinengineeringapplicationsforturbulentmixinginnuclearreactors.
