建筑空气动力学

BU/LD/NGAERODYWAM/CS^TornLow$on^-.-Mhhiiperia!CoHegePressBU!LD!NGAERODYNAM!CSBU)LD!NGAERODYNAMtCSTomLawsonFREngUniverst/ofBn'sto/ImperialCollegePressfuMij/Mj&yImperialCollegePress57SheltonStreetCoventGardenLondonWC2H9HEDijfriTpHf^J&yWorldScientificPublishingCo.Pte.Ltd.POBox128,FarrerRoad,Singapore912805t/&4q#;c!.'SuiteIB,1060MainStreet,RiverEdge,NJ07661t/Ko#c!.'57SheltonStreet,CoventGarden,LondonWC2H9HEBritishLibraryCatatoguing-in-PublicationDataAcataloguerecordforthisbookisavailablefromtheBritishLibrary.BUILDINGAERODYNAMICSCopyrightO2001byImperialCollegePress/tHn'gnUre^rvea*.7VH.S^oo%,orparHfnereo/;maynof^?erepro^MceJ;'nany/ormor^yanymean.!,e/ec^ron;'corwec/!an;ca/,mc^M^;'ngpnoMcopymg,recordingorany/n/or/HafionyforageanJrern'gva/.sy.!femnow(:nosv/!orfo^?e;'nwnfgJ,WiYAoM!wn7MnpermiM;on/romfAePM^/Mn^r.Forphotocopyingofmaterialinthisvolume,pleasepayacopyingfeethroughtheCopyrightClearanceCenter,Inc.,222RosewoodDrive,Danvers,MA01923,USA.Inthiscasepermissiontophotocopyisnotrequiredfromthepublisher.ISBN1-86094-187-7PrintedinSingapore.BuildingAerodynamicsAcknowledgements.VAcknowledgementsItisimpossibletomention,orevenbeconsciousof,allthosepeoplewhoseworkandcontacthaveaffectedone'sthinkingorhaveimplantedideaswhichhavelaterflourished.Totrytodosowouldproduceomissionswhichonewouldregretandwhichwouldneverbefullyredeemed.Iwouldlike,therefor,tothankallwhohaveeducatedmeinWindEngineering,andhopethattheythinkthatIhavedonethesubjectjusticeinthisbook.However,IwouldliketoexpressmydelightthatNickCookandWaynePearcehavecometoBristoltocarryontheworkofWindEngineeringhere,andtothankthemforallthehelpthemhavegivenmeinthewritingofthisbook.IwouldliketothankColinWoodforhishelpinfillingthegapsinmyknowledge.Severalofthephotographs,whichareCrownCopyright,appearinthetextanddosobycourtesyoftheDirectoroftheBuildingResearchEstablishment.IwouldliketothankPauline,whoseencouragementandbackingmademeacceptthecontracttowritethisbookinthefirstplace,andwhohaskeptmeincomfortwhileIfinishedit.BuildingAerodynamicsPrefaceVMPrefaceThisbookiswrittenspecificallyforthepracticingArchitectandEngineer.ThevariousinteractionsofthewindwithbuildingsareconsideredintheirseparateChapters,eachofwhichhasanIntroductioninwhichtheinteractionisexplainedingeneralterms.DetaileddataarepresentedintherestofeachchapterexplainingtheextentofquantifiableinformationwhichcanbemadeavailablebytheWindEngineertotheDesignTeamsothatthebestcompromisebetweentherequirementsofwindandalltheothercompetingconsiderationscanbemade.TypicalTablesandFiguresfromrealsituationsarepresentedasillustrationsofallmeasurementsandcalculations.Theoryhasbeenkepttoaminimum,andisonlypresentedwhen,intheauthor'sopinion,theanalysisisnotwellknownoriscentraltotheargument.Itishopedthattheintroductionstoallthechapterswillbeofinteresttoeveryone,buttotrytopreventareaderfrombeingputoffbylongdetaileddiscussionswhichmightnotinteresthim,aSummaryforeachchapterispresentedunderSummarieswhichsuggeststhepartsofthechapterwhichcanbeomittedbysomereaderswithoutlossofenvolvementintheteamdiscussions,whilst,atthesametime,drawingthesamereader'sattentionistothosepartsofthechapterwhichareappropriatetohisdetailedunderstandingofthesubject.AlthoughwrittenforthepracticingArchitectandEngineer,itisappropriatetothestudentArchitectandEngineerbecausehisneedsarethesame.BuildingAerodynamicsContentsIXContentsSummaries11TheWind91.1GlobalCirculation.91.2ExtratropicalCyclonesorTemperateSystems.121.3StrongWindSpeeds.131.3.1.MeanVelocityProfile.141.3.2.TurbulenceProfile.161.3.3.SpectralDensityFunction.161.3.4.LengthScalesofTurbulence.181.4.StabilityoftheAtmosphere.191.4.1.Definition.191.4.2.Implications.201.4.2.1.Inversions.1.4.2.2.StableandUnstableAtmospheres.1.4.2.3.ApplicationtoWindTunnels.1.5.ApplicationtotheWindEngineer.221.5.1.DisplacementHeightandGroundRoughness.231.5.2.ReferenceWindSpeed.241.5.3.JustificationforUsingStrongWindData.261.5.3.1.WindLoading.1.5.3.2.WindEnvironment.XBuildingAerodynamicsContents1.5.3.3.VentilationStudies.1.5.3.3.1.NaturalVentilation.1.5.3.3.2.ForcedVentilation.1.5.3.4.SmokeDispersioninthecaseofFire.1.5.3.5.RemovalofEffluentfromBuildings.1.5.3.5.1.NearField.1.5.3.5.2.FarField.2.FlowAroundBluffBodiesinTbrbulentFfow292.1.Shear-freeFlow(TwoDimensional).312.1.1.DynamicSimilarity.312.1.1.1.ReynoldsNumber.2.1.1.2.MachNumber.2.1.1.3.FroudeNumber.2.1.1.4.StrouhalNumber.2.1.1.5.Pressure,ForceandMomentCoefficients.2.1.2.SeparationandReattachment.352.1.2.1.ReynoldsNumber.2.1.2.2.TurbulenceintheApproachingAir.2.1.2.3.SurfaceRoughness.2.1.2.4.PressureGradient.2.1.2.5.EffectiveReynoldsNumber.2.1.3.DifferencebetweenSharp-EdgesandRoundedBuildings.392.1.4.OscillatoryFlowPatterns.412.1.4.1.VortexShedding.2.1.4.2.FlowSwitching.2.1.5.SpecialShapes.462.1.5.1.StrandedCables.2.1.5.2.SwingofaCricketBall.2.1.5.3.ElectrifiedTrainOverheadLine.2.2.ShearFlow482.2.1.ThreeDimensionalFlow.482.2.2.LeadingEdgeVortices.522.2.3.SeparationBubbleonRoof.542.2.4.EffectofProximityofOtherBuildings.55BuildingAerodynamicsContentsXI3.WindLoading573.1.Quasi-StaticApproa