传热学传热学HeattransferHeattransfer张靖周能源与动力学院Lecture10PrincipleandTechnologyofEnhancedConvectiveHeatTransfer强化对流换热原理与技术FocusofthislecturePrincipleofenhancedconvectiveheattransferaswellasitsdevelopmentTechnicalapproachesofenhancedconvectiveheattransferforlaminarandturbulentflowJetimpingementheattransfer(1)Mainobjectivesofheattransferresearches1-1Introduction1-1IntroductionIgnoringthermalradiation�Regardingatypicalheattransferprocess固壁辐射对流对流辐射导热Howtoenhancek?Reducingheatresistances�Basicheattransferdisciplinarian�Technicalapproachesforcontrollingheattransfer(2)EnhancedheattransfertechnologyCompactheatexchangerHeatpipe■Effectivecooling■Compactheatexchanger■Efficiencyelement-heatpipeForinstances�Developedvigorouslyfrom1960s�Tightlyrelatedtoapplications19601970198019902000年代200018001600140012001000T(K)�涡轮进口温度发展�国外高温合金发展�国内高温合金发展F119-PW-100推重比10~1900KF22�Coolingdemond�InletT(3)Developmentofenhancedheattransfer�SignificantdemandandhugechallengeApplicationofenhancedheattransferinaero-engines19601970198019902000年代200018001600140012001000T(K)�涡轮进口温度发展�国外高温合金发展�国内高温合金发展新一代推重比20~2300K推重比12-15~2100KWhat?How?F119-PW-100推重比10~1900KF22�Coolingdemond�InletTBottlenecktechnologiesBreakthrough�ItsinnovationistightlyassociatedwithadvancesinnewmaterialandmanufacturingprocessMicro-finsheatsinkPiezoelectric-fanheatsink1-2PrincipleofEnhancedConvection1-2PrincipleofEnhancedConvection�Theoryofconvectiveheattransfer)(0fyTThyT−=⎟⎟⎠⎞⎜⎜⎝⎛∂∂−=λForsingle-phase,theinherentphysicalmechanismonconvectiveheattransferenhancementreliesonincreaseoftemperaturegradientnearwall�Howtorealizetheincreasingoftemperaturegradientinthevicinityofwall?�Arethereanydifferencesintheheattransferenhancementtechniquesforthelaminarflowandturbulentflow?DiscussionsToanswerabovequestionsViewingfrom?TherespectivefeaturesforthevelocityandtemperaturedistributionintheboundarylayerLaminarflowTu...