雨课堂学堂在线学堂云《Heat Transfer（西安交大 ）》单元测试考核答案

注：不含主观题第1题单选题(2.5分)Atroomtemperaturethethermalconductivitiesofdrybrickandwaterare0.4W/(m‧K)and0.6W/(m‧K),respectively.Howmuchwillbethethermalconductivityofawettedbrick?Alessthan0.4W/(m‧K)Blessthan0.6W/(m‧K)Clargerthan0.6W/(m‧K)第2题单选题(1.5分)FortheheatconductionshowninthefollowingFig.,if

t1>t2,thenAheatfluxincreasesintheaxisdirectionBheatfluxdecreasesintheaxisdirectionCheatfluxremainsconstantintheaxisdirection第3题单选题(2分)Whenafoundryiscooledincastingsand,itwillshrink(itsvolumeisreduced).Henceastillairgapwillbeformedbetweenfoundryandcastingsand.WhatistheheattransfermechanismthroughthegapAconvectiveheattransferBheatconductionandradiationCradiation第4题单选题(1分)TheheattransferratethroughconductionisdeterminedbytheFourier’sLaw.WhatdoestheminussigninthisLawmean?AThedirectionofheattransmissionistheoppositeofthetemperatureincreasedirectionBThedirectionofheattransmissionisthesameasthetemperatureincreasedirectionCThedirectionofheattransmissionisnothingtodowiththetemperatureincreasedirection第5题单选题(2分)Itisacommonexperiencetofeelchillyinwinterandwarminsummeratthesameroomtemperature.ThemajorreasonisAdifferentconvectiveheattransferBdifferentheatconductionthroughthefloorCdifferentradiativeheattransferbetweensurroundingwallandhumanbody第6题单选题(1分)Thetemperatureofanincandescent

light

filamentisashighas2500-3000K.ThemajorheattransfermechanismfromthefilamenttoenvironmentisAConductionthroughtheresidualairinthebulbBConvectiveheattransferoftheresidualairinthebulbCRadiativeheattransferfromthefilament第7题单选题(2分)Oncethedoorofarefrigeratorisopened,chillywillbesoonfeltbyhumanbody.Whatisthemajorheattransfermechanism?AHeatconductionthroughtheairbetweenbodyandrefrigeratorBConvectiveheattransferofcoldairintherefrigeratorCRadiativeheattransferofthecoldwallintherefrigerator第8题单选题(1分)TheunitoftheoverallheattransfercoefficientisAW/(m^2‧K)BW/(m‧K)CW/KDW/m^2第9题单选题(1分)Thethermalconductionresistancethroughawall,R,withsurfaceareaA,thicknessandthermalconductivity

isABCD第10题单选题(1分)Amongthefollowingstatementspleaseidentifywhichoneiscorrect.AAtanytemperaturematterradiatesBOnlyathightemperaturematterradiatesCOnlyatlowtemperaturematterradiatesDAtanytemperaturetheradiativeenergyabsorbedbymatterequalsitsemittedradiativeenergy第11题单选题(1.5分)Anoverallheattransferprocessincludesatleastfollowingsub-processes:conductionthroughthewall,convectiveheattransferatthetwosidesofthewall.Pleaseidentifywhichoneiscorrectamongthefollowingstatements.ATheoverallheattransfercoefficientonlydependsonthewallthicknessanditsthermalconductivityBTheoverallheattransfercoefficientonlydependsontheconvectiveheattransferatthetwosidesofthewallCTheoverallheattransfercoefficientdependsontheconvectiveheattransfercoefficientsatthetwosides,thewallthicknessanditsthermalconductivity第12题单选题(1.5分)Theheattransferfromaroomradiatortoenvironmentiscarriedoutthroughfollowingmechanism.AConvectiveheattransferbetweenradiatorwallandsurroundingairBRadiativeheattransferbetweenradiatorwallandsurroundingcoldsurfacesCConvectiveheattransferbetweenradiatorwallandsurroundingairandradiativeheattransferbetweenradiatorwallandsurroundingcoldsurfaces第13题多选题(2分)Enhancementofconvectiveheattransferisanimportantsubjectinheattransferresearch.WhicharetheefficientmethodsforenhancingconvectiveheattransferfromNewton’slawofcooling?AIncreaseofheattransfertemperaturedifferenceBIncreaseofheattransferareaCIncreaseofconvectiveheattransfercoefficientDIncreasebothheattransferareaandconvectiveheattransfercoefficientsimultaneously正确答案：BCD2.12Problems第1题多选题(2分)Thefollowingschematicdiagramsshowtwodifferentsituationsofone-dimensional,steady-stateheatconductionwithoutinternalheatsourceoflargeplatesinCartesiancoordinates.Whichofthefollowingoptionsarecorrect?()AInFigure(a),thetemperaturegradientispositive.BInFigure(a),heatfluxispositive.CInFigure(b),thetemperaturegradientispositive.DInFigure(b),heatfluxispositive.正确答案：BD第2题单选题(1分)Theone-dimensional,steady-stateheatconductionoftheroundtablewithconstantthermophysicalpropertiesshowninthefollowingfigure,ifand

，whichofthefollowingoptionsarecorrect?()ATemperaturedecreasesalongxaxis.BHeatflux|q|decreasesalongxaxis.CThecurveoftemperaturedistributionisconvexdownward.DHeattransferratedecreasesalongxaxis.第3题单选题(1分)Multi-layerinsulatingmaterialshaveidenticalthickness.Theyareemployedtoinsulatethecylindricalandflatwall.Whichofthefollowingoptionsiscorrect?()

APutthematerialwithlargerthermalconductivityonthehighertemperaturesideofthecylindricalwall.BPutthematerialwithlargerthermalconductivityonthehighertemperaturesideoftheflatwall.CTheplacementofmaterialswithdifferentthermalconductivitiesdoesnotaffectthethermalinsulationeffectoftheflatwall.DTheplacementofmaterialswithdifferentthermalconductivitiesdoesnotaffectthethermalinsulationeffectofthecylindricalwall.第4题单选题(1分)Asthefollowingfigureshown,innerwallandouterwallofacylindricalwallhavedifferenttemperatures.Thethermalconductivityofthematerialisconstant.Theschematicdiagramofthetemperaturedistributionprofileshouldbe()

AGreencurve.BBlackcurve.CRedcurve.DUnabletojudge.第5题多选题(3分)Inthefollowingsituationsofheatconduction,forwhichoneswecannotobtainheattransferratebyintegratingtheFourier’slawofheatconductiondirectly?AHeatconductionwithinnerheatsource.BHeatconductionofthecylinderwall.CMulti-dimensionalheatconduction.DUnsteadyheatconduction.正确答案：ACD第6题单选题(1分)Thethicknessofastraightfinofuniformcross-sectionisδ,thethermalconductivityofthematerialisλandtheconvectiveheattransfercoefficientbetweenthestraightfinsurfaceandambientish.Fortheheatconductionthroughthestraightfin,whichonecanbeapproximatelytreatedasaone-dimensionalheatconductionproblem?()ALargethermalconductivityofmaterial.BSmallfinthickness.CLargeconvectiveheattransfercoefficientbetweenthestraightfinsurfaceandambient

.DBi=hδ/(2λ)≪1第7题多选题(3分)Forthedouble-pipethermometer,whichofthefollowingmeasurescanreducethetemperaturemeasurementerror?AImprovetheflowvelocityofthemeasuredfluid.BReducethewallthicknessofthedouble-pipethermometer.CReplacesteelwithcopperasthedouble-pipematerial.DLeanthedouble-pipethermometerinthedirectionofincomingflow.正确答案：ABD第8题多选题(3分)Fortemperaturedistributionoftheplatewall,cylindricalwall,sphericalshellandfinundertheconditionsofone-dimensional,steadystateandnoinnerheatsource,whichofthefollowingstatementsarecorrect?()AAslongasthematerialthermophysicalpropertiesareconstant,thetemperaturedistributionoftheone-dimensionalheatconductionofplatewallislinear.BThetemperaturedistributionofheatconductionofthecylinderwallisacurvebecausethematerialthermophysicalpropertiesarenotconstant.CThetemperaturedistributionofheatconductionofthesphericalshellisacurvebecausetheheatconductionareachanges.DThetemperaturedistributionofthefinisacurvebecauseheattransferratesofconductionarenotequal.正确答案：ACD第9题单选题(1分)Whichofthefollowingstatementsaboutthefinefficiencyiscorrect?ATheoverallfinsurfaceefficiencymustbelargerthanthefinefficiency.BThefinefficiencyofalongfinislargerthanthatofashortfin.CIfafinlengthisdoubled,theheattransferratewillbedoubledaccordingly.DThefinefficiencyisdeterminedifthefinmaterialandfinshapearefixed.第10题多选题(3分)Thereisalargeplateofthicknessδ

withauniforminternalheatsource.Thenfortheone-dimensionalsteady-stateheatconductionproblemoccurringintheplate,thecorrectstatementsare()ABothboundarysidesmaybeheatingsurfaces.BOneboundarysidemaybeacoolingsurface,whiletheothersidemaybeaheatingsurface.CBothboundarysidesmaybecoolingsurfaces.DOneboundarysidemaybeanadiabaticsurface,andtheotheronemaybeaheatingsurface.EOneboudarysidemaybeacoolingsurfaceandtheotheronemaybeanadiabaticsurface.FBothboundarysidesmaybeadiabatic.正确答案：BCE第11题多选题(3分)Thereisalongcylindricalwallwithinnerandouterradiusesof

r1andr2

,respectively,andauniforminternalheatsource

.Fortheradialone-dimensionalsteadyheatconductionoccurringinthecylindricalwall,thecorrectstatementsare()AOneboundarysidemaybeaheatingsurfaceandtheothermaybeacoolingsurface.BBothboundarysidesmaybecoolingsurface.CBothboundarysidesmaybeheatingsurface.DOneboundarymaybeanadiabaticsurface,andtheotheronemaybeaheatingsurface.EOneboundarymaybeacoolingsurfaceandtheotheronemaybeanadiabaticsurface.FBothboundarysidesmaybeadiabatic.正确答案：ABE第12题多选题(3分)Thereisalargeplateofthicknessδ

withauniforminternalheatsource

.Thenfortheone-dimensionalsteady-stateheatconductionoccurringintheplate,thecorrectstatementsare().ABothboundarysidesmaybeheatingsurfaces.BBothboundarysidesmaybecoolingsurfaces.COneboundarysidemaybeaheatingsurface,whiletheothersidemaybeacoolingsurface.DOneboudarysidemaybeacoolingsurfaceandtheotheronemaybeanadiabaticsurface.EOneboundarysidemaybeaheatingsurface,andtheotheronemaybeanadiabaticsurface.FBothboundarysidesmaybeadiabatic.正确答案：ACE第13题多选题(2分)Thereisalargeplatewithauniforminternalheatsource.Fortheone-dimensionalsteady-stateheatconductionoccurringintheplate,inthefollowingstatementsaboutthepositionofthehighesttemperatureintheplate,thecorrectstatementsare().AThehighesttemperaturemustbeinsidetheplate.BThehighesttemperaturemustbeattheboundary.CThehighesttemperaturemightbeattheboundary.DThehighesttemperaturemightbeinsidetheplate.正确答案：CD第14题多选题(3分)Thereisalongcylindricalwallwithauniforminternalheatsource.Fortheradialone-dimensionalsteadyheatconductioninthecylindricalwall,inthefollowingstatementsaboutthepositionofthehighesttemperatureinthewall,thecorrectstatementsare().AThehighesttemperaturemustbeinsidethewall.BThehighesttemperaturemustbeattheinnerboundary.CThehighesttemperaturemaybeattheouterboundary.DThehighesttemperaturemaybeattheinnerboundary.EThehighesttemperaturemayoccuratsomewhereinsidethecylinderwall.正确答案：CDE第15题单选题(1分)Thereisalargeplatewallwiththickness,

constantthermophysicalproperties,uniforminternalheatsource

,andsymmetricalcoolingonbothsides.Whichoneofthefollowingstatementsabouttherelationbetweenheatfluxandxintheplatewall(steadystate)istrue?()A|q|

isgoingtodecreasefirstandthenincreaseasxincreases.B|q|

isgoingtodecreaseasxincreases.C|q|isgoingtoincreasefirstandthendecreaseasxincreases.D|q|isgoingtoincreaseasxincreases.E|q|isaconstant.FItcannotbedetermined.第16题单选题(1分)Thereisalargeplateofthickness

withuniforminternalheatsourceandsymmetricalcoolingonbothsides.Ifweconsiderthevariationofthermophysicalpropertieswithtemperature,whichoneofthefollowingstatementsabouttherelationbetweenheatflux|q|andxintheplatewall(steadystate)istrue?()A|q|isgoingtodecreasefirstandthenincreaseasxincreases.B|q|

isgoingtodecreaseasxincreases.C|q|

isgoingtoincreasefirstandthendecreaseasxincreases.D|q|

isgoingtoincreaseasxincreases.E|q|

isaconstant.FItcannotbedetermined.第17题单选题(1分)Thereisalargeplatewallofthicknesswithconstantthermophysicalpropertiesandauniforminternalheatsource.Theboundariesofx=0

andx=δ

maintainuniformandconstanttemperaturesat

t1and

t2

(t1≠t2),respectively.Fortheone-dimensionalsteady-stateheatconductionintheplate,inthefollowingstatementsabout|q|x=0

and|q|x=δ

,thecorrectoneis().AThesetwovaluesareequal.BThesetwovaluesarenotequal.CThesetwovaluesmightbeequal.DThesetwovaluesnightbenotequal.第18题单选题(1分)Thereisalongcylindricalwallwithinnerandouterradiusesof

r1andr2,respectively,andauniforminternalheatsource

.Theinnnerandouterboundarysurfacesmaintainthesameuniformconstanttemperaturetw.Fortheradialone-dimensionalsteady-stateheatconductioninthecylindricalwall,whichoneofthefollowingstatementsabouttherelationbetweenheatflux|q|andrinthewalliscorrect?()A|q|isgoingtodecreasefirstandthenincreaseasincreases.B|q|

isgoingtodecreaseasincreases.C|q|

isgoingtoincreasefirstandthendecreaseasincreases.D|q|

isgoingtoincreaseasincreases.E|q|

isaconstant.FItcannotbedetermined.3.8Problems第1题单选题(1分)TheBiotnumbercanbeconsideredastheratioofwhichofthefollowingtwoterms：ATheconductionthermalresistancetotheconvectivethermalresistance.BTheconvectivethermalresistancetotheconductionthermalresistance.CThethermalenergystoragecapacitytotheconductionthermalresistance.DThethermalenergystoragecapacitytotheconvectionthermalresistance.第2题单选题(1分)LumpedparametermethodoftransientheatconductionsituationsisvalidwhentheBiotnumberis：AApproximatelyoneBVerysmallCVerylargeDAnyrealnumber第3题单选题(1分)HeislerdiagramisonlyapplicablewhenFo>0.2,becauseAkeepsconstantwhenFo>0.2.BTheHeislerdiagramisdrawnaccordingtotheregularregime.WhenFo>0.2,thetransientheatconductionenterstheregularregime.CHeislerchartistoodensetobeappliedwhenFo≤0.2.DWhenFo≤0.2,thelinesontheHeislerdiagramarecurves,soitisdifficulttoapplythem.第4题单选题(2分)Heattransferoccursbetweentwohigh-temperaturesolidsofthesamematerialandtheairaroundthem.Thefirstsolidiscooledbyafan,whilethesecondsolidisnaturallycooled.Thelumpedparametermethodmaybemoresuitablefor:AThefirstsolidBThesecondsolidCThesameappliesDUnabletodetermine第5题单选题(1.5分)Considerthehotbakedpotatoesontheplate.Inthefirstminute,itwasobservedthatthetemperatureofpotatoesdroppedby4℃.Temperaturedropinthesecondminuteis:AOver4℃BEqualto4℃CLessthan4℃DUnabletodetermine第6题单选题(1.5分)AsfortheapplicabilityofHeislerdiagramforone-dimensionalunsteady-stateheatconductioninlargeplates,longcylindersandspheres,whichstatementiscorrect?AItisapplicabletoallkindsofsituationsunderthethirdkindofboundaryconditions.BItisonlysuitableforthethirdkindofboundaryconditionandtheheatingprocesswithuniforminitialtemperature.CItisonlysuitableforthethirdkindofboundaryconditionandthecoolingprocesswithuniforminitialtemperature.DItissuitableforthethirdkindofboundaryconditionsandtheheatingorcoolingprocesswithuniforminitialtemperature.第7题多选题(3分)Theunsteady-stateheatconductionwillhappenwhenAenvironmentalconditionschange.Bmaterialpropertiesaretemperature-dependent.Ctheinitialtemperatureisnon-uniform.Dtheinternalheatsourceisrelatedtotime.正确答案：AD第8题单选题(1分)Considertheunsteady-stateheatconductioninanobject.Afteralongtime,

Asteadystateheatconductionstagemustbereached.Btheobjectmustreachanewstateofheatbalance.Ctheheatconductionintheobjectmuststillbeunsteady.Dtheheatconductionstageorstatecannotbedetermined.第9题单选题(2分)Twolargeplates1and2withthesamethickness2δhavethesameuniforminitialtemperaturet_0.Suddenly,theyareheatedsimutaneouslyandsymmetricallyintheenvironmentoft_∞.Theheattransfercoefficientsofthetwoplatesareh_1andh_2,respectively，andh_1=1.25h_2.Assumingthatthethermalconductivityλ_1andλ_2ofthetwoplatesareconstant,andλ_1=1.25λ_2,thenAThetemperaturechangeinplate1mustbefasterthanthatinplate2.BThetemperaturechangeinplate1mustbeslowerthanthatinplate2.CThespeedoftemperaturechangeoftwoplatesisequal.DThetemperaturechangesofthetwoplatesareuncertain.第10题单选题(2分)Twoobjects1and2withnointernalheatsourcehavethesamegeometryanduniforminitialtemperature.Whentheyarecooled(orheated)inanenvironmentwiththesametemperature,whichofthefollowingstatementabouttherelativespeedoftemperaturechangeofthetwoobjectsiscorrect?AThetemperatureofobjectswithlargethermalconductivity,λ,andheatcapacity,ρc,willchangerapidly.BThetemperatureoftheobjectwithlargethermaldiffusivity,a,andsmallthermalconductivity,λ,mustchangerapidly.CThetemperatureoftheobjectwithlargethermaldiffusivity,a,andlargethermalconductivity,λ,mustchangerapidly.DThetemperatureofobjectwithsmallthermaldiffusivity,a,andsmallthermalconductivity,λ,mustbeslow第11题单选题(3分)Asteelballwithadiameterof5cmandaninitialtemperatureof450℃issuddenlyplacedinairwithatemperatureof30℃forcooling.Thetotalheattransfercoefficientbetweensteelballandsurroundingenvironmentis24W/(m^2.K).Itisknownthatc=0.48kJ/(kg.K)，ρ=7753kg/m^3，λ=33W/(m⋅K)ofsteel.Thetimerequiredfortheballtobecooledto300℃isA0.108hB0.123hC0.145hD0.158h第12题单选题(3分)Thesteelcastingiscooledto90%oftheoriginaltemperaturedifferencewithin30minutesinstillair.Thetimerequiredtocoolthesamecastingto90%oftheoriginaltemperaturedifferenceinaflowingairwithaconvectiveheattransfercoefficientof5timesthatofstillairisA3minB6minC9minD12min第13题单选题(3分)Copperball

(ρ=8933kg/m^3，λ=401W/(m⋅K)，c=385J/(kg⋅K))attheinitialtemperatureof200℃iscooledinairat30℃for2minutes.Iftheballdiameteris2cmandtheconvectiveheattransfercoefficientis80W/(m^2⋅K),thecentertemperatureoftheballattheendofcoolingisA87℃B98℃C104℃D126℃4.12Problems第1题多选题(2分)Thedifferenceequationsofthefirst-orderderivativeandthesecond-orderderivativecangivethecorrectresultsifthetemperaturedistributionisuniform.So,whichexpressionisincorrectbasedonthischaracterisric.ABCD正确答案：BD第2题多选题(4分)ThebasicproceduresofnumericalmethodsinheatconductionincludeAgridgenerationBformulationofthediscretizedequationsof

nodesCsolvingtheAlgebraicEquationsDmathematicalmodel正确答案：ABCD第3题多选题(3分)Inthefollowingstatementsonnumericalmethods,whichis/arecorrect?ANumericalsolutionsareexact.BNumericalsolutionsareapproximate.CThegridandtimestepsinfluencetheaccuracyofnumericalsolutionsDThequalityofgrid

affectstheaccuracyofnumericalsolutions正确答案：BCD第4题多选题(3分)Inthediscretizationintime,thetypicaldifferencemethodsincludeAforwarddifferenceBbackwarddifferenceCcentraldifferenceDimplicitdifferenceEexplicitdifference正确答案：ABC第5题多选题(2分)Thebasicwaystoestablishthedifference/discretizedequationareATaylor'sseriesexpansionBenergybalancemethodCintegrationmethodDdifferentialmethod正确答案：AB第6题多选题(2分)Oniterativemethod,whichthefollowingstatementsarecorrect?Atheiterationisboundtoconverge.Btheiterationmaydiverge.Citisveryimportanthowtoarrangetheiteration.Dtheiterativemethodissuperiortothedirectmethod.正确答案：BC第7题单选题(1分)Comparedwiththesteady-stateproblem,thekeytothenumericalsolutionoftheunsteadyheatconductionproblemisAdiscretizationintimeBdiscretizationinspaceCgridgenerationDhowtosolvethealgebraicequations第8题单选题(1分)TheexplicitschemeisAunstableBconditionallystableCabsolutelystable第9题单选题(1分)TheimplicitschemeisAunstableBconditionallystableCabsolutelystable第10题单选题(5分)Considerasteadyheatconductioninalonghollowsteeltubewiththethermalconductivity

λandthegenerationasshowninFigure.Theouterwallisexposedtothefluidwithtemperaturet∞andtheconvectiveheattransfercoefficientish.Ifsolvingthisproblembynumericalmethods,pleasewriteoutthediscretizationequationofboundarynodeN.ABC第11题单选题(6分)Considera2-DsteadyheatconductioninarectangularmadeoftwodifferentmaterialsasshowninFigure.Thereexistsnoheatgeneration.pleasewriteoutthediscretizationequationofnodeP.AB5.9Problems第1题单选题(1分)Whichofthefollowingstatementsaboutconvectionheattransferiswrong:ATheheattransfercoefficienthisrelatedtoheattransferprocessandisaffectedbymultiplefactors.BGenerally,theheattransfercoefficientofwaterissmallerthanthatofair.CConvectionheattransfercanbeclassifiedintonaturalconvectionandforcedconvectionaccordingtotheflownature.DThevalueofforcedconvectionheattransfercoefficientofwatercouldreachtensofthousands.第2题单选题(1分)Whichofthefollowingstatementsaboutconvectionheattransferiswrong:AInaconvectionheattransferprocess,heatconductionandconvectionworksimultaneously.BInaconvectionheattransferprocess,thefluiddoesnotneedtodirectlycontactwiththesolidwall.CTheequationq=hΔtisabasicformulaforcalculatingconvectionheattransfer,buthisnotaphysicalpropertyparameter.DAninhomogeneoustemperaturefielddoesnotnecessarilycausenaturalconvection.第3题单选题(2分)Fullydevelopedlaminarflowoccursbetweentwoparallelplates,andthefollowingthreefiguresaretemperaturedistributioncurvesoffluidonthecrosssectioninthefullydevelopedregion.Pleasematchthefollowingfigureswithcorrespondingboundaryconditions:

A123B213C321D312第4题单选题(1分)Whichofthefollowingstatementsaboutboundarylayeriscorrect:AForconvectionheattransfer,theintroductionofaboundarylayercanreducecalculationarea.BByintroducingvelocityboundarylayer,theflowregioncanbedividedintoboundarylayerregionandfreestreamregion,andtheflowinboundarylayerregioncanbeconsideredasanidealfluidflow.CThereisonlylaminarflowbutnoturbulentflowinvelocityboundarylayer.DInathermalboundarylayer,themagnitudeoftemperaturegradientatthewallsurfaceisnotthelargest.第5题单选题(1分)Whichofthefollowingstatementsaboutanalogytheoryiscorrect:ATheReynoldsanalogyworksatPrt≠1.BAnalogytheorycouldnotbeusedtosolveheattransferproblemsofturbulentflow.CThemomentumtransferandheattransferintheturbulentprocessarebothcausedbypulsationoffluidmicelles,sothereisanintrinsicconnectionbetweenheattransferandflowresistance.DAnalogytheorycanalsobeusedfortwophysicalphenomenawithnosimilarityingoverningequations.第6题单选题(1分)Oil,airandliquidmetalflowoveranisothermalplateinlaminarstate,andthetemperatureandvelocitydistributionsinboundarylayerofthethreekindsofflowaredrawnasfollows.Pleasematchthefluidtypeswithcorrespondingdiagraminthefollowing:AAir,oil,liquidmetalBLiquidmetal,oil,airCOil,liquidmetal,airDLiquidmetal,air,oil第7题单选题(1分)Aspecificfluidisusedforamodelexperimentaltestofinternaltubeflow.Ifthetubediameterofthemodelexperimentaltestis1/10oforiginalprototype,andotherconditionsarethesame.Whentheflowsimilarityissatisfied,theflowvelocityofthemodeltestis:AEqualtotheprototype.B10timestheprototype.C1/10oftheprototype.DUncertain.第8题单选题(1分)Airat100°Cand101.3kPaflowsoveraflatplateataspeedof100m/s,andthetemperatureofflatplateis30°C.Thethermalboundarylayerthicknessandthelocalheattransfercoefficientofboundarylayeratadistanceof3cmfromtheleadingedgeofplateare:A0.382mm,112.6W/(m2·K)B0.432mm,112.6W/(m2·K)C0.432mm,56.3W/(m2·K)D0.382mm,56.3W/(m2·K)第9题单选题(1分)WhichofthefollowingworkingfluidshasthesmallestPrandtlnumber(Pr):AWater.BAir.CLiquidmetalsodium.DTransformeroil.第10题单选题(1分)Forlaminarheattransferofalongitudinallyflowacrossflatplate,therelationshipbetweenlocalheattransfercoefficientsomewhereh_xandaverageheat-transfercoefficientfromtheleadingedgeofplatetothissectionh_lis:Ah_x>h_lBh_x<h_lCh_x=h_lDUncertain第11题单选题(1分)Whichofthefollowingstatementsaboutsimilarityprincipleiscorrect:AForphenomenathataresimilartoeachother,thesimilarityparametersofthesamenamearenotnecessarilyequal.BSimilarconceptsexistintwophenomenathatarenotthesamekind.CFortwosamekindphenomena,ifthesingle-valuedconditionsaresimilaranddefinedsimilarityparametersofthesamenameareequal,thetwophenomenamustbesimilar.DTheonlywaytoobtainsimilarityparameterisdimensionalanalysismethod.第12题多选题(2分)Whichofthefollowingoptionshaseffectsonconvectionheattransfer:AThesurfaceconditionforheattransfer.BWhetherchemicalreactionsoccurduringthemixedflowofmultiplefluids.CThetypeoffluid.DWhetherthefluidflowisdrivenbyexternalpower.正确答案：ABCD第13题多选题(2分)Whichofthefollowingconditionsshouldbenotedwhensimilarityparameterequationisapplied:AThecharacteristiclengthshouldbeselectedintheprescribedmannerofsimilarityparameterequation.BThecharacteristicvelocityshouldbecalculatedinaprescribedmanner.CThereferencetemperatureshouldbeselectedintheprescribedmannerofsimilarityparameterequation.DThesimilarityparameterequationcannotbearbitrarilyextendedbeyondtherangeofexperimentalparametersoftheequation.正确答案：ABCD第14题多选题(2分)Thedifferentialequationofconvectionheattransferis.Whichofthefollowingparametersarerelatedtoheattransfercoefficienth:AThetemperaturedifferencebetweenthewallandfluid.BThevelocityfield.CThethermalconductivityoffluid.DTheabsolutevalueoftemperaturegradientoffluidhuggingthewallsurfaceveryclosely.正确答案：ABCD第15题多选题(2分)Theassumptionsmadeinderivingthesimplifiedenergyequationofmovingfluidincludethat:AFluidphysicalpropertiesareconstant,andthereisnointernalheatgenerati