资源描述：
《CORRELATION EQUATIONS FOR FREE CONVECTION HEAT TRANSFER IN HORIZONTAL LAYERS OF AIR AND WATER》由会员上传分享，免费在线阅读，更多相关内容在学术论文-天天文库。
1、hr..I.HearMassTronsJer.Vol.18,pp.879-884.PergamonPress1975.PrintedinGreatBritainCORRELATIONEQUATIONSFORFREECONVECTIONHEATTRANSFERINHORIZONTALLAYERSOFAIRANDWATERK.G.T.HOLLAND&~G.D.RArTHBYtandL.KONICEK*(Received4June1974andinrevisedform21October1974)Abstract-Newexperimentalm
2、easurementsarereportedonthenaturalconvectiveheattransportthroughahorizontallayerofair,coveringtheRayleighnumberrangefromsub-criticalto4x106.WhenthesedataarecombinedwithGoldsteinandChusdataforair,thefullsetofdatapointsaredemonstratedtobearaNusseltnumberdependencewhichisasym
3、ptotictoal/3powerontheRayleighnumberastheRayleighnumberapproachesinhnity.Theasymptoticcoefficientofproportionalityisconsistentwiththatpredictedbyasimpleconductionlayermodelwhichisdescribed.Knowledgeoftheasymptotehaspermittedasimplebutaccuratecorrelationequationtobeobtained
4、,validforthefullrangeofRayleighnumber.Byextension,asimilarcorrelationequationisalsoobtainedforwater.NOMENCLATUREflowconsistsofsteadyrolls.Subsequentincreasesintheconstantinequation(2)[dimensionless];Rayleighnumberproducesflowsofincreasingcom-depthoffluidlayer[ml;plexity,th
5、eexactnatureoftheflowpatterndependingaccelerationofgravity[m/s2];onthePrandtlnumber.Thusthetransitiontotime-convectiveheat-transfercoefficient,acrossunsteadyIlowvariesfromRaN5500forPr=0.7tofluidlayer[W/mK];RaN55000forPr=8500[2].ForRayleighnumberkthermalconductivityoffluid[
6、W/mK];greaterthanaboutlo6thestructureoftheflowisNu,Nusseltnumber,=hd/k[dimensionless];generallyconsideredtobefullyturbulent.pr,Prandtlnumber,=v/u;MeasurementsofthefluidtemperatureprofileathighRayleighnumbershowsaboundary-layertypestruc-Ra,Rayleighnumber,=ga(T1-r,)d3ture,th
7、erebeinganearlyisothermalinnercorewithVUhightemperaturegradientsclosetotheboundary[dimensionless];surfaces.AsurprisingobservationresultingfromtheT,,T,,temperatureoflowerandupperplatemeasurementsonwaterisareversalinthetemperaturerespectively[K];gradientintheinnercore[3].Ino
8、bservingtheflowATBL,temperaturedifferenceacrossboundarystructureathighRayleighnumberwithw
