Comparisonofthermo-hydraulicperformancesoflargescalevortexflow(LSVF)andsmallscalevortexflow(SSVF)mixingvanesin17×17nuclearrodbundleOriginalResearchArticle

Spacergridsinthenuclearfuelrodassemblymaintainaconstantdistancebetweenrods,secureflowpassageandpreventthedamageoftherodbundlefromflow-inducedvibration.Themixingvanesattachedtothespacergridsgeneratevortexflowsinthesubchannelsandenhancetheheattransferperformanceoftherodbundle.Varioustypesofmixingvaneshavebeendevelopedtoproducecrossflowsbetweensubchannelsaswellasvortexflowsinthesubchannels. Theshapesofthemixingvanehavebeenimprovedtogeneratelargerturbulenceandcrossflowmixing.Inthepresentstudy,twotypesoflargescalevortexflow(LSVF)mixingvanesandtwotypesofsmallscalevortexflow(SSVF)mixingvanesareexamined.SSVF-singleisconventionalsplittypeandSSVF-coupleissplittypewithdifferentarrayingmethod.LSVFmixingvanehasdifferentgeometryandarrayingmethodtomakelargescalevortex.17×17rodbundlewitheightspansofmixingvanesissimulatedusingtheIBM690supercomputer.TheFLUENTcodeandIBMsupercomputerisemployedtocalculatetheflowfieldandheattransferinthesubchannels. Turbulenceintensities,maximumsurfacetemperaturesoftherodbundle,heattransfercoefficientsandpressuredropsofthefourkindsofmixingvanesarecompared.LSVFmixingvanesproducedhigherturbulenceintensityandheattransfercoefficientthanSSVFmixingvanes.Consequently,LSVFmixingvaneincreasesthethermalefficiencyandsafetyoftherodbundle.