CFDinvestigationofhelicalwire-wrapped7-pinfuelbundleandthechallengesinmodelingfullscale217pinbundleOriginalResearchArticle

Flowandtemperaturedistributionsofsodiuminaheatgeneratingfuelpinbundlewithhelicallywoundspacerwirehavebeenpredictedfrombasicprinciplesbysolvingthethree-dimensionalconservationequationsofmass,momentumandenergy,forawiderangeofReynoldsnumber.Turbulencehasbeenmodeledusingthek–ɛturbulencemodel.ThegeometrydetailsofthebundleandheatfluxfromthefuelpinaresimilartothatoftheIndianPrototypeFastBreederReactor(PFBR)thatiscurrentlyunderconstruction.Thefocusofthestudyistoassesstheeffectoftransverseflowinpromotingflowandtemperatureuniformity.Itisseenthattheratioofmaximumtransversevelocitytothemaximumaxialvelocityisnearlyequaltothetangentoftherollingupangleofthespacerwire.Duetothewirewrap,thedifferenceinbulksodiumtemperaturebetweentheperipheralandcentralsub-channelsisreducedtobyafactorof4whencomparedtothatwithoutspacerwire.Thefilmdropatthejunctionbetweenwireandthepinisfoundtobeonly∼70°C.Thepredictedresultsarefoundtobeincloseagreementwiththatoftheexperimentalresultsreportedinliterature.Thepresentstudyconsidersa7-pinbundleassemblyofonehelicalpitch.Thecomputationaltimeandmemoryrequiredfora217pinwith15pitchesassemblyisascertainedtobe500timesthatrequiredforthecurrentstudy.Hence,researchactivitieshavebeendirectedtowardsdevelopingaparallelCFDcodeandstructuralmeshgenerationsoftware.