建筑给排水中英文对照外文翻译文献图文 7页

建筑给排水中英文对照外文翻译文献图文　　建筑给排水中英文对照外文翻译文献_文图文03?????建筑给排水中英文对照外文翻译文献??(文档含英文原文和中文翻译)??外文?Sealedbuildingdrainageandventsystems?—anapplicationofactiveairpressuretransientcontrolandsuppressionAbstract?Theintroductionofsealedbuildingdrainageandventsystemsisconsideredaviablepropositionforplexbuildingsduetotheuseofactivepressuretransientcontrolandsuppressionintheformofairadmittancevalvesandpositiveairpressureattenuatorscoupledwiththeinterconnectionofthework'sverticalstacks.?Thispaperpresentsasimulationbasedonafour-stackworkthatillustratesflowmechanismswithinthepipeworkfollowingbothappliancedischargegenerated,andsewerimposed,transients.Thissimulationidentifiestheroleoftheactiveairpressurecontroldevicesinmaintainingsystempressuresatlevelsthatdonotdepletetrapseals.?Furthersimulationexerciseswouldbenecessarytoprovideproofofconcept,anditwouldbeadvantageoustoparallelthesewithlaboratory,andpossiblysite,trialsforvalidationpurposes.Despitethiscautiontheinitialresultsarehighlyencouragingandaresufficienttoconfirmthepotentialtoprovidedefinitebenefitsintermsofenhancedsystemsecurityaswellasincreasedreliabilityandreduced\ninstallationandmaterialcosts.?Keywords:Activecontrol;Trapretention;Transientpropagation?Nomenclature?C+-——characteristicequations?c——wavespeed,m/s?D——branchorstackdiameter,m?f——frictionfactor,UKdefinitionviaDarcyΔh=4fLu2/2Dg?g——aelerationduetogravity,m/s2?K——losscoefficient?L——pipelength,m?p——airpressure,N/m2?t——time,s?u——meanairvelocity,m/s??x——distance,m?γ——ratiospecificheats??Δh——headloss,m?Δp——pressuredifference,N/m2?Δt——timestep,s?Δx——internodallength,m?ρ——density,kg/m3?ArticleOutline?Nomenclature?1.Introduction—airpressuretransientcontrolandsuppression?2.Mathematicalbasisforthesimulationoftransientpropagationinmulti-stackbuildingdrainageworks?3.Roleofdiversityinsystemoperation?4.Simulationoftheoperationofamulti-stacksealedbuildingdrainageandventsystem?5.Simulationsignconventions?6.Waterdischargetothework?7.Surchargeatbaseofstack1?8.Sewerimposedtransients?9.Trapsealoscillationandretention?10.Conclusion—viabilityofasealedbuildingdrainageandventsystem?1.Airpressuretransientsgeneratedwithinbuildingdrainageandventsystemsasanaturalconsequenceofsystemoperationmayberesponsiblefortrapsealdepletionandcrosscontaminationofhabitablespace[1].Traditionalmodesoftrapsealprotection,basedonthe\nVictorianengineer'sobsessionwithodourexclusion[2],[3]and[4],dependpredominantlyonpassivesolutionswhererelianceisplacedoncrossconnectionsandverticalstacksventedto?atmosphere[5]and[6].Thisapproach,whilebothprovenandtraditional,hasinherentweaknesses,includingtheremotenessoftheventterminations[7],leadingtodelaysinthearrivalofrelievingreflections,andthemultiplicityofopenrooflevelstackterminationsinherentwithinplexbuildings.Theplexityoftheventsystemrequiredalsohassignificantcostandspaceimplications[8].?Thedevelopmentofairadmittancevalves(AAVs)overthepasttwodecadesprovidesthedesignerwithameansofalleviatingnegativetransientsgeneratedasrandomappliancedischargescontributetothetimedependentwater-flowconditionswithinthesystem.AAVsrepresentanactivecontrolsolutionastheyresponddirectlytothelocalpressureconditions,openingaspressure?fallstoallowareliefairinflowandhencelimitthepressureexcursionsexperiencedbytheappliancetrapseal[9].?However,AAVsdonotaddresstheproblemsofpositiveairpressuretransientpropagationwithinbuildingdrainageandventsystemsasaresultofintermittentclosureofthefreeairpaththroughtheworkorthearrivalofpositivetransientsgeneratedremotelywithinthesewersystem,possiblybysomesurchargeevent\ndownstream—includingheavyrainfallinbinedsewerapplications.?Thedevelopmentofvariablevolumecontainmentattenuators[10]thataredesignedtoabsorbairflowdrivenbypositiveairpressuretransientspletesthenecessarydeviceprovisiontoallowactiveairpressuretransientcontrolandsuppressiontobeintroducedintothedesignofbuildingdrainageandventsystems,forboth‘standard’buildingsandthoserequiringparticularattentiontobepaidtothesecurityimplicationsofmultiplerooflevelopenstackterminations.Thepositiveairpressureattenuator(PAPA)consistsofavariablevolumebagthatexpandsundertheinfluenceofapositivetransientandthereforeallowssystemairflowstoattenuategradually,thereforereducingthelevelofpositivetransientsgenerated.TogetherwiththeuseofAAVstheintroductionofthePAPAdeviceallowsconsiderationofafullysealedbuildingdrainageandventsystem.illustratesbothAAVandPAPAdevices,notethatthewaterlesssheathtrapactsasanAA??Fig.1.Activeairpressuretransientsuppressiondevicestocontrolbothpositiveandnegativesurges.Activeairpressuretransientsuppression?andcontrolthereforeallowsforlocalizedinterventiontoprotecttrapsealsfrombothpositiveandnegativepressureexcursions.Thishas?distinctadvantagesoverthetraditionalpassiveapproach.Thetimedelay\ninherentinawaitingthereturnofarelievingreflectionfromaventopentoatmosphereisremovedandtheeffectofthetransientonalltheothersystemtrapspassedduringitspropagationisavoided.?2.Mathematicalbasisforthesimulationoftransientpropagationinmulti-stackbuildingdrainageworks.?ThepropagationofairpressuretransientswithinbuildingdrainageandventsystemsbelongstoawellunderstoodfamilyofunsteadyflowconditionsdefinedbytheStVenantequationsofcontinuityandmomentum,andsolvableviaafinitedifferenceschemeutilizingthemethodofcharacteristicstechnique.Airpressuretransientgenerationandpropagationwithinthesystemasaresultofairentrainmentbythefallingannularwaterinthesystemverticalstacksandthereflectionandtransmissionofthesetransientsatthesystemboundaries,includingopenterminations,connectionstothesewer,appliancetrapsealsandbothAAVandPAPAactivecontroldevices,maybesimulatedwithprovenauracy.Thesimulation[11]provideslocalairpressure,velocityandwavespeedinformationthroughoutaworkattimeanddistanceintervalsasshortas0.001sand300mm.Inaddition,thesimulationreplicateslocalappliancetrapsealoscillationsandtheoperationofactivecontroldevices,therebyyieldingdataonworkairflowsandidentifyingsystemfailuresandconsequences.Whilethesimulationhasbeen\nextensivelyvalidated[10],itsusetoindependentlyconfirmthemechanismofSARSvirusspreadwithintheAmoyGardensoutbreakinxxhasprovidedfurtherconfidenceinitspredictions[12].?Airpressuretransientpropagationdependsupontherateofchangeofthesystemconditions.Increasingannulardownflowgeneratesanenhancedentrainedairflowandlowersthesystempressure.Retardingtheentrainedairflowgeneratespositivetransients.Externaleventsmayalsopropagatebothpositiveandnegativetransientsintothework.?Theannularwaterflowinthe‘wet’stackentrainsanairflowduetotheconditionof‘noslip’establishedbetweentheannularwaterandaircoresurfacesandgeneratestheexpectedpressurevariationdownaverticalstack.Pressurefallsfromatmosphericabovethestackentryduetofrictionandtheeffectsofdrawingairthroughthewatercurtainsformedatdischargingbranchjunctions.Inthelowerwetstackthepressurerecoverstoaboveatmosphericduetothetractionforcesexertedontheairflowpriortofallingacrossthewatercurtainatthestackbase.?Theapplicationofthemethodofcharacteristicstothemodellingofunsteadyflowswasfirstrecognizedinthe1960s[13].TherelationshipsdefinedbyJack[14]allowsthesimulationtomodelthetractionforceexertedontheentrainedair.Extensiveexperimentaldata\nallowedthedefinitionofa‘pseudo-frictionfactor’applicableinthewetstackandoperableacrossthewaterannularflow/entrainedaircoreinterfacetoallowbineddischargeflowsandtheireffectonair?。　　　　内容仅供参考