Author/Authors :
X.Cheng، نويسنده , , N.I.Tak، نويسنده ,
Abstract :
CFDanalysiswascarriedoutforthermal–hydraulicbehaviorofheavyliquidmetalflows,especiallylead–bismutheutectic,insub-channelsofbothtriangularandsquarelattices.Effectofvariousparameters,e.g.turbulencemodelsandpitch-to-diameterratio,onthethermal–hydraulicbehaviorwasinvestigated.Amongtheturbulencemodelsselected,onlythesecondorderclosureturbulencemodelsreproducethesecondaryflow.Fortheentireparameterrangestudiedinthispaper,theamplitudeofthesecondaryflowislessthan1%ofthemeanflow.Astronganisotropicbehaviorofturbulenceisobserved.Theturbulencebehaviorissimilarinbothtriangularandsquarelattices.Theaverageamplitudeoftheturbulentvelocityfluctuationacrossthegapisabouthalfoftheshearvelocity.ItisonlyweaklydependentonReynoldsnumberandpitch-to-diameterratio.Astrongcircumferentialnon-uniformityofheattransferisobservedintightrodbundles,especiallyinsquarelattices.RelatedtotheoverallaverageNusseltnumber,CFDcodesgivesimilarresultsforbothtriangularandsquarerodbundles.ComparisonoftheCFDresultswithbundletestdatainmercuryindicatesthattheturbulentPrandtlnumberforHLMflowsinrodbundlesiscloseto1.0athighPecletnumberconditions,andincreasesbydecreasingPecletnumber.Basedonthepresentresults,the
