建筑给排水-外文文献翻译1 32页

本科毕业设计外文文献及译文文献、资料题目：Sealedbuildingdrainageandventsystems文献、资料来源：国道数据库文献、资料发表（出版）日期：2016.6院（部）：市政与环境工程学院专业：给水排水工程班级：水工122姓名：杨涛学号：20120411048指导教师：谭凤训翻译日期：2016.6\n外文文献：Sealedbuildingdrainageandventsystems—anapplicationofactiveairpressuretransientcontrolandsuppressionAbstractTheintroductionofsealedbuildingdrainageandventsystemsisconsideredaviablepropositionforcomplexbuildingsduetotheuseofactivepressuretransientcontrolandsuppressionintheformofairadmittancevalvesandpositiveairpressureattenuatorscoupledwiththeinterconnectionofthenetwork'sverticalstacks.Thispaperpresentsasimulationbasedonafour-stacknetworkthatillustratesflowmechanismswithinthepipeworkfollowingbothappliancedischargegenerated,andsewerimposed,transients.Thissimulationidentifiestheroleoftheactiveairpressurecontroldevicesinmaintainingsystempressuresatlevelsthatdonotdepletetrapseals.Furthersimulationexerciseswouldbenecessarytoprovideproofofconcept,anditwouldbeadvantageoustoparallelthesewithlaboratory,andpossiblysite,trialsforvalidationpurposes.Despitethiscautiontheinitialresultsarehighlyencouragingandaresufficienttoconfirmthepotentialtoprovidedefinitebenefitsintermsofenhancedsystemsecurityaswellasincreasedreliabilityandreducedinstallationandmaterialcosts.Keywords:Activecontrol;Trapretention;TransientpropagationNomenclatureC+-——characteristicequationsc——wavespeed,m/sD——branchorstackdiameter,mf——frictionfactor,UKdefinitionviaDarcyΔh=4fLu2/2Dgg——accelerationduetogravity,m/s2K——losscoefficientL——pipelength,mp——airpressure,N/m2t——time,su——meanairvelocity,m/sx——distance,mγ——ratiospecificheats\nΔh——headloss,mΔp——pressuredifference,N/m2Δt——timestep,sΔx——internodallength,mρ——density,kg/m3ArticleOutlineNomenclature1.Introduction—airpressuretransientcontrolandsuppression2.Mathematicalbasisforthesimulationoftransientpropagationinmulti-stackbuildingdrainagenetworks3.Roleofdiversityinsystemoperation4.Simulationoftheoperationofamulti-stacksealedbuildingdrainageandventsystem5.Simulationsignconventions6.Waterdischargetothenetwork7.Surchargeatbaseofstack18.Sewerimposedtransients9.Trapsealoscillationandretention10.Conclusion—viabilityofasealedbuildingdrainageandventsystem1.Airpressuretransientsgeneratedwithinbuildingdrainageandventsystemsasanaturalconsequenceofsystemoperationmayberesponsiblefortrapsealdepletionandcrosscontaminationofhabitablespace[1].Traditionalmodesoftrapsealprotection,basedontheVictorianengineer'sobsessionwithodourexclusion[2],[3]and[4],dependpredominantlyonpassivesolutionswhererelianceisplacedoncrossconnectionsandverticalstacksventedtoatmosphere[5]and[6].Thisapproach,whilebothprovenandtraditional,hasinherentweaknesses,includingtheremotenessoftheventterminations[7],leadingtodelaysinthearrivalofrelievingreflections,andthemultiplicityofopenrooflevelstackterminationsinherentwithincomplexbuildings.Thecomplexityoftheventsystemrequiredalsohassignificantcostandspaceimplications[8].Thedevelopmentofairadmittancevalves(AAVs)overthepasttwodecadesprovidesthedesignerwithameansofalleviatingnegativetransientsgeneratedasrandomappliancedischargescontributetothetimedependentwater-flowconditionswithinthesystem.AAVsrepresentanactivecontrolsolutionastheyresponddirectlytothelocalpressureconditions,openingaspressure\nfallstoallowareliefairinflowandhencelimitthepressureexcursionsexperiencedbytheappliancetrapseal[9].However,AAVsdonotaddresstheproblemsofpositiveairpressuretransientpropagationwithinbuildingdrainageandventsystemsasaresultofintermittentclosureofthefreeairpaththroughthenetworkorthearrivalofpositivetransientsgeneratedremotelywithinthesewersystem,possiblybysomesurchargeeventdownstream—includingheavyrainfallincombinedsewerapplications.Thedevelopmentofvariablevolumecontainmentattenuators[10]thataredesignedtoabsorbairflowdrivenbypositiveairpressuretransientscompletesthenecessarydeviceprovisiontoallowactiveairpressuretransientcontrolandsuppressiontobeintroducedintothedesignofbuildingdrainageandventsystems,forboth‘standard’buildingsandthoserequiringparticularattentiontobepaidtothesecurityimplicationsofmultiplerooflevelopenstackterminations.Thepositiveairpressureattenuator(PAPA)consistsofavariablevolumebagthatexpandsundertheinfluenceofapositivetransientandthereforeallowssystemairflowstoattenuategradually,thereforereducingthelevelofpositivetransientsgenerated.TogetherwiththeuseofAAVstheintroductionofthePAPAdeviceallowsconsiderationofafullysealedbuildingdrainageandventsystem.Fig.1illustratesbothAAVandPAPAdevices,notethatthewaterlesssheathtrapactsasanAAVundernegativelinepressure.Fig.1.Activeairpressuretransientsuppressiondevicestocontrolbothpositiveandnegativesurges.Activeairpressuretransientsuppressionandcontrolthereforeallowsforlocalizedinterventiontoprotecttrapsealsfrombothpositiveandnegativepressureexcursions.Thishas\ndistinctadvantagesoverthetraditionalpassiveapproach.Thetimedelayinherentinawaitingthereturnofarelievingreflectionfromaventopentoatmosphereisremovedandtheeffectofthetransientonalltheothersystemtrapspassedduringitspropagationisavoided.2.Mathematicalbasisforthesimulationoftransientpropagationinmulti-stackbuildingdrainagenetworks.ThepropagationofairpressuretransientswithinbuildingdrainageandventsystemsbelongstoawellunderstoodfamilyofunsteadyflowconditionsdefinedbytheStVenantequationsofcontinuityandmomentum,andsolvableviaafinitedifferenceschemeutilizingthemethodofcharacteristicstechnique.Airpressuretransientgenerationandpropagationwithinthesystemasaresultofairentrainmentbythefallingannularwaterinthesystemverticalstacksandthereflectionandtransmissionofthesetransientsatthesystemboundaries,includingopenterminations,connectionstothesewer,appliancetrapsealsandbothAAVandPAPAactivecontroldevices,maybesimulatedwithprovenaccuracy.Thesimulation[11]provideslocalairpressure,velocityandwavespeedinformationthroughoutanetworkattimeanddistanceintervalsasshortas0.001 sand300 mm.Inaddition,thesimulationreplicateslocalappliancetrapsealoscillationsandtheoperationofactivecontroldevices,therebyyieldingdataonnetworkairflowsandidentifyingsystemfailuresandconsequences.Whilethesimulationhasbeenextensivelyvalidated[10],itsusetoindependentlyconfirmthemechanismofSARSvirusspreadwithintheAmoyGardensoutbreakin2003hasprovidedfurtherconfidenceinitspredictions[12].Airpressuretransientpropagationdependsupontherateofchangeofthesystemconditions.Increasingannulardownflowgeneratesanenhancedentrainedairflowandlowersthesystempressure.Retardingtheentrainedairflowgeneratespositivetransients.Externaleventsmayalsopropagatebothpositiveandnegativetransientsintothenetwork.Theannularwaterflowinthe‘wet’stackentrainsanairflowduetotheconditionof‘noslip’establishedbetweentheannularwaterandaircoresurfacesandgeneratestheexpectedpressurevariationdownaverticalstack.Pressurefallsfromatmosphericabovethestackentryduetofrictionandtheeffectsofdrawingairthroughthewatercurtainsformedatdischargingbranchjunctions.Inthelowerwetstackthepressurerecoverstoaboveatmosphericduetothetractionforcesexertedontheairflowpriortofallingacrossthewatercurtainatthestackbase.Theapplicationofthemethodofcharacteristicstothemodellingofunsteadyflowswasfirstrecognizedinthe1960s[13].TherelationshipsdefinedbyJack[14]allowsthesimulationtomodelthetractionforceexertedontheentrainedair.Extensiveexperimentaldataallowedthedefinitionofa‘pseudo-frictionfactor’applicableinthewetstackandoperableacrossthewaterannularflow/entrainedaircoreinterfacetoallowcombineddischargeflowsandtheireffectonair\nentrainmenttobemodelled.ThepropagationofairpressuretransientsinbuildingdrainageandventsystemsisdefinedbytheStVenantequationsofcontinuityandmomentum[9],(1)(2)Thesequasi-linearhyperbolicpartialdifferentialequationsareamenabletofinitedifferencesolutiononcetransformedviatheMethodofCharacteristicsintofinitedifferencerelationships,Eqs.(3)–(6),thatlinkconditionsatanodeonetimestepinthefuturetocurrentconditionsatadjacentupstreamanddownstreamnodes,Fig.2.Fig.2.StVenantequationsofcontinuityandmomentumallowairflowvelocityandwavespeedtobepredictedonanx-tgridasshown.Note,.FortheC+characteristic:(3)when(4)andtheC-characteristic:(5)when(6)wherethewavespeedcisgivenbyc=(γp/ρ)0.5.(7)\nTheseequationsinvolvetheairmeanflowvelocity,u,andthelocalwavespeed,c,duetotheinterdependenceofairpressureanddensity.Localpressureiscalculatedas(8)Suitableequationslinklocalpressuretoairflowortotheinterfaceoscillationoftrapseals.Thecaseoftheappliancetrapsealisofparticularimportance.Thetrapsealwatercolumnoscillatesundertheactionoftheappliedpressuredifferentialbetweenthetransientsinthenetworkandtheroomairpressure.TheequationofmotionfortheU-bendtrapsealwatercolumnmaybewrittenatanytimeas(9)Itshouldberecognizedthatwhilethewatercolumnmayriseontheapplianceside,converselyonthesystemsideitcanneverexceedadatumleveldrawnatthebranchconnection.Inpracticaltermstrapsealsaresetat75or50 mmintheUKandotherinternationalstandardsdependentuponappliancetype.Trapsealretentionisthereforedefinedasadepthlessthantheinitialvalue.Manystandards,recognizingthetransientnatureoftrapsealdepletionandtheopportunitythatexistsforre-chargeonappliancedischargeallow25%depletion.Theboundaryequationmayalsobedeterminedbylocalconditions:theAAVopeningandsubsequentlosscoefficientdependsonthelocallinepressureprediction.EmpiricaldataidentifiestheAAVopeningpressure,itslosscoefficientduringopeningandatthefullyopencondition.Appliancetrapsealoscillationistreatedasaboundaryconditiondependentonlocalpressure.Deflectionofthetrapsealtoallowanairpathto,orfrom,theapplianceordisplacementleadingtooscillationalonemaybothbemodelled.Reductionsintrapsealwatermassduringthetransientinteractionmustalsobeincluded.3.RoleofdiversityinsystemoperationIncomplexbuildingdrainagenetworkstheoperationofthesystemappliancestodischargewatertothenetwork,andhenceprovidetheconditionsnecessaryforairentrainmentandpressuretransientpropagation,isentirelyrandom.Notwosystemswillbeidenticalintermsoftheirusageatanytime.Thisdiversityofoperationimpliesthatinter-stackventingpathswillbeestablishediftheindividualstackswithinacomplexbuildingnetworkarethemselvesinterconnected.Itisproposedthatthisdiversityisutilizedtoprovideventingandtoallowseriousconsiderationtobegiventosealeddrainagesystems.Inordertofullyimplementasealedbuildingdrainageandventsystemitwouldbenecessaryforthenegativetransientstobealleviatedbydrawingairintothenetworkfromasecurespaceand\nnotfromtheexternalatmosphere.Thismaybeachievedbytheuseofairadmittancevalvesoratapredeterminedlocationwithinthebuilding,forexampleanaccessibleloftspace.Similarly,itwouldbenecessarytoattenuatepositiveairpressuretransientsbymeansofPAPAdevices.InitiallyitmightbeconsideredthatthiswouldbeproblematicaspositivepressurecouldbuildwithinthePAPAinstallationsandthereforenegatetheirabilitytoabsorbtransientairflows.ThismayagainbeavoidedbylinkingtheverticalstacksinacomplexbuildingandutilizingthediversityofuseinherentinbuildingdrainagesystemsasthiswillensurethatPAPApressuresarethemselvesalleviatedbyallowingtrappedairtoventthroughtheinterconnectedstackstothesewernetwork.Diversityalsoprotectstheproposedsealedsystemfromsewerdrivenoverpressureandpositivetransients.Acomplexbuildingwillbeinterconnectedtothemainsewernetworkviaanumberofconnectingsmallerboredrains.Adversepressureconditionswillbedistributedandthenetworkinterconnectionwillcontinuetoprovideventingroutes.Theseconceptswillbedemonstratedbyamulti-stacknetwork.4.Simulationoftheoperationofamulti-stacksealedbuildingdrainageandventsystemFig.3illustratesafour-stacknetwork.ThefourstacksarelinkedathighlevelbyamanifoldleadingtoaPAPAandAAVinstallation.WaterdownflowsinanystackgeneratenegativetransientsthatdeflatethePAPAandopentheAAVtoprovideanairflowintothenetworkandouttothesewersystem.PositivepressuregeneratedbyeitherstacksurchargeorsewertransientsareattenuatedbythePAPAandbythediversityofusethatallowsonestack-to-sewerroutetoactasareliefroutefortheotherstacks.Thenetworkillustratedhasanoverallheightof12m.Pressuretransientsgeneratedwithinthenetworkwillpropagateattheacousticvelocityinair.Thisimpliespipeperiods,fromstackbasetoPAPAofapproximately0.08sandfromstackbasetostackbaseofapproximately0.15s.Inordertosimplifytheoutputfromthesimulationnolocaltrapsealprotectionisincluded—forexamplethetrapscouldbefittedwitheitherorbothanAAVandPAPAasexamplesofactivecontrol.Traditionalnetworkswouldofcourseincludepassiveventingwhereseparateventstackswouldbeprovidedtoatmosphere,howeverasealedbuildingwoulddispensewiththisventingarrangement.\nFig.3.Fourstackbuildingdrainageandventsystemtodemonstratetheviabilityofasealedbuildingsystem.Ideallythefoursewerconnectionsshownshouldbetoseparatecollectiondrainssothatdiversityinthesewernetworkalsoactstoaidsystemselfventing.Inacomplexbuildingthisrequirementwouldnotbearduousandwouldinallprobabilitybethenorm.Itisenvisagedthatthestackconnectionstothesewernetworkwouldbedistributedandwouldbetoabelowgrounddrainagenetworkthatincreasedindiameterdownstream.Otherconnectionstothenetworkwouldinallprobabilitybefrombuildingsthatincludedthemoretraditionalopenventsystemdesignsothatafurtherlevelofdiversityisaddedtooffsetanydownstreamsewersurchargeeventsoflongduration.Similarconsiderationsledtothecurrentdesignguidancefordwellings.Itisstressedthatthenetworkillustratedisrepresentativeofcomplexbuildingdrainagenetworks.Thesimulationwillallowarangeofappliancedischargeandsewerimposedtransientconditionstobeinvestigated.Thefollowingappliancedischargesandimposedsewertransientsareconsidered:1.w.c.dischargetostacks1–3overaperiod1–6sandaseparatew.c.dischargetostack4between2and7s.2.Aminimumwaterflowineachstackcontinuesthroughoutthesimulation,setat0.1L/s,torepresenttrailingwaterfollowingearliermultipleappliancedischarges.\n3.A1sdurationstackbasesurchargeeventisassumedtooccurinstack1at2.5s.4.Sequentialsewertransientsimposedatthebaseofeachstackinturnfor1.5sfrom12to18s.Thesimulationwilldemonstratetheefficacyofboththeconceptofactivesurgecontrolandinter-stackventinginenablingthesystemtobesealed,i.e.tohavenohighlevelroofpenetrationsandnoventstacksopentoatmosphereoutsidethebuildingenvelope.Theimposedwaterflowswithinthenetworkarebasedon‘real’systemvalues,beingrepresentativeofcurrentw.c.dischargecharacteristicsintermsofpeakflow,2l/s,overallvolume,6l,andduration,6s.Thesewertransientsat30mmwatergaugearerepresentativebutnotexcessive.Table1definesthew.c.dischargeandsewerpressureprofilesassumed.Table1.w.c.dischargeandimposedsewerpressurecharacteristicsw.c.dischargecharacteristicImposedsewertransientatstackbaseTimeDischargeflowTimePressureSecondsl/sSecondsWatergauge(mm)Starttime0.0Starttime0.0+22.0+0.530.0+42.0+0.530.0+60.0+0.50.05.SimulationconventionsItshouldbenotedthatheightsforthesystemstacksaremeasuredpositiveupwardsfromthestackbaseineachcase.Thisimpliesthatentrainedairflowtowardsthestackbaseisnegative.AirflowenteringthenetworkfromanyAAVsinstalledwillthereforebeindicatedasnegative.Airflowexitingthenetworktothesewerconnectionwillbenegative.Airflowenteringthenetworkfromthesewerconnectionorinducedtoflowupanystackwillbepositive.Waterdownflowinaverticalishoweverregardedaspositive.Observingtheseconventionswillallowthefollowingsimulationtobebetterunderstood.6.WaterdischargetothenetworkTable1illustratesthew.c.dischargesdescribedabove,simultaneousfrom1stostacks1–3andfrom2stostack4.Abaseofstacksurchargeisassumedinstack1from2.5to3s.AsaresultitwillbeseenfromFig.4thatentrainedairdownflowsareestablishedinpipes1,6and14as\nexpected.However,theentrainedairflowinpipe19isintothenetworkfromthesewer.Initially,asthereisonlyatricklewaterflowinpipe19,theentrainedairflowinpipe19duetothew.c.dischargesalreadybeingcarriedbypipes1,6and14,isreversed,i.e.upthestack,andcontributestotheentrainedairflowdemandinpipes1,6and14.TheAAVonpipe12alsocontributesbutinitiallythisisasmallproportionoftherequiredairflowandtheAAVfluttersinresponsetolocalpressureconditions.Fig.4.Entrainedairflowsduringappliancedischarge.Followingthew.c.dischargetostack4thatestablishesawaterdownflowinpipe19from2 sonwards,thereversedairflowinitiallyestablisheddiminishesduetothetractionappliedbythefallingwaterfilminthatpipe.However,thesuctionpressuresdevelopedintheotherthreestacksstillresultsinacontinuingbutreducedreversedairflowinpipe19.Asthewaterdownflowinpipe19reachesitsmaximumvaluefrom3 sonwards,theAAVonpipe12opensfullyandanincreasedairflowfromthissourcemaybeidentified.Theflutterstageisreplacedbyafullyopenperiodfrom3.5to5.5 s.Fig.5illustratestheairpressureprofilefromthestackbaseinbothstacks1and4at2.5 sintothesimulation.Theairpressureinstack4demonstratesapressuregradientcompatiblewiththereversedairflowmentionedabove.Theairpressureprofileinstack1istypicalforastackcarryinganannularwaterdownflowanddemonstratestheestablishmentofapositivebackpressureduetothewatercurtainatthebaseofthestack.\nFig.5.Airpressureprofileinstacks1and4illustratingthepressuregradientdrivingthereversedairflowinpipe19.TheinitialcollapsedvolumeofthePAPAinstalledonpipe13was0.4l,withafullyexpandedvolumeof40l,howeverduetoitssmallinitialvolumeitmayberegardedascollapsedduringthisphaseofthesimulation.7.Surchargeatbaseofstack1Fig.6indicatesasurchargeatthebaseofstack1,pipe1from2.5to3 s.Theentrainedairflowinpipe1reducestozeroatthestackbaseandapressuretransientisgeneratedwithinthatstack,Fig.6.Theimpactofthistransientwillalsobeseenlaterinadiscussionofthetrapsealresponsesforthenetwork.Fig.6.Airpressurelevelswithinthenetworkduringthew.c.dischargephaseofthesimulation.Notesurchargeatbasestack1,pipe1at2.5s.\nItwillalsobeseen,Fig.6,thatthepredictedpressureatthebaseofpipes1,6and14,intheabsenceofsurcharge,conformtothatnormallyexpected,namelyasmallpositivebackpressureastheentrainedairisforcedthroughthewatercurtainatthebaseofthestackandintothesewer.Inthecaseofstack4,pipe19,thereversedairflowdrawnintothestackdemonstratesapressuredropasittraversesthewatercurtainpresentatthatstackbase.Thesimulationallowstheairpressureprofilesupstack1tobemodelledduring,andfollowing,thesurchargeillustratedinFig.6.Fig.7(a)and(b)illustratetheairpressureprofilesinthestackfrom2.0to3.0 s,theincreasinganddecreasingphasesofthetransientpropagationbeingpresentedsequentially.ThetracesillustratethepropagationofthepositivetransientupthestackaswellasthepressureoscillationsderivedfromthereflectionofthetransientatthestackterminationattheAAV/PAPAjunctionattheupperendofpipe11.Fig.7.(a)Sequentialairpressureprofilesinstack1duringinitialphaseofstackbasesurcharge.(b)Sequentialairpressureprofilesinstack1duringfinalphaseofstackbasesurcharge.8.SewerimposedtransientsTable2illustratestheimpositionofaseriesofsequentialsewertransientsatthebaseofeach\nstack.Fig.8demonstratesapatternthatindicatestheoperationofboththePAPAinstalledonpipe13andtheself-ventingprovidedbystackinterconnection.Fig.8.Entraindairflowsasaresultofsewerimposedpressuretransients.Asthepositivepressureisimposedatthebaseofpipe1at12 s,airflowisdrivenupstack1towardsthePAPAconnection.However,asthebaseoftheotherstackshavenotayethadpositivesewerpressurelevelsimposed,asecondaryairflowpathisestablisheddownwardstothesewerconnectionineachofstacks2–4,asshownbythenegativeairflowsinFig.8.AstheimposedtransientabatessothereversedflowreducesandthePAPAdischargesairtothenetwork,againdemonstratedbythesimulation,Fig.8.Thispatternrepeatsaseachofthestacksissubjectedtoasewertransient.Fig.9illustratestypicalairpressureprofilesinstacks1and2.Thepressuregradientinstack2confirmstheairflowdirectionupthestacktowardstheAAV/PAPAjunction.Itwillbeseenthatpressurecontinuestodecreasedownstack1untilitrecovers,pipes1and3,duetotheeffectofthecontinuingwaterflowinthosepipes.ThePAPAinstallationreactstothesewertransientsbyabsorbingairflow,Fig.10.ThePAPAwillexpanduntiltheaccumulatedairinflowreachesitsassumed40 lvolume.AtthatpointthePAPAwillpressurizeandwillassisttheairflowoutofthenetworkviathestacksunaffectedbytheimposedpositivesewertransient.Notethatasthesewertransientisappliedsequentiallyfromstacks1–4thispatternisrepeated.ThevolumeofthehighlevelPAPA,togetherwithanyothersintroducedintoamorecomplexnetwork,couldbeadaptedtoensurethatnosystempressurizationoccurred.\nFig.9.Airpressureprofileinstack1and2duringthesewerimposedtransientinstack2,15sintothesimulation.Fig.10.PAPAvolumeandAAVthroughflowduringsimulation.TheeffectofsequentialtransientsateachofthestacksisidentifiableasthePAPAvolumedecreasesbetweentransientsduetotheentrainedairflowmaintainedbytheresidualwaterflowsineachstack.9.TrapsealoscillationandretentionTheappliancetrapsconnectedtothenetworkmonitorandrespondtothelocalbranchairpressures.Themodelprovidesasimulationoftrapsealdeflection,aswellasfinalretention.Fig.11(a,b)presentthetrapsealoscillationsforonetraponeachofthestacks1and2,respectively.Astheairpressurefallsinthenetwork,thewatercolumninthetrapisdisplacedsothattheappliancesidewaterlevelfalls.However,thesystemsidelevelisgovernedbythelevelofthebranchentryconnectionsothatwaterislosttothenetwork.ThiseffectisillustratedinbothFig.11(a)and(b).\nTransientconditionsinthenetworkresultintrapsealoscillation,howeverattheendoftheeventthetrapsealwillhavelostwaterthatcanonlybereplenishedbythenextapplianceusage.Ifthetransienteffectsareseverethanthetrapmaybecometotallydepletedallowingapotentialcrosscontaminationroutefromthenetworktohabitablespace.Fig.11(a)and(b)illustratethetrapsealretentionattheendoftheimposednetworktransients.Fig.11.(a)Trapsealoscillation,trap2.(b)Trapsealoscillation,trap7.Fig.11(a),representingthetraponpipe2,illustratestheexpectedinducedsiphonageoftrapsealwaterintothenetworkasthestackpressurefalls.Thesurchargeeventinstack1interruptsthisprocessat2s.Thetraposcillationsabatefollowingthecessationofwaterdownflowinstack1.Theimpositionofasewertransientisapparentat12sbythewatersurfacelevelrisingintheappliancesideofthetrap.Amoreseveretransientcouldhaveresultedin‘bubblingthrough’atthisstageifthetrapsystemsidewatersurfacelevelfelltothelowestpointoftheU-bend.Thetrapsealoscillationsfortrapsonpipes7,Fig.11(b)and15,areidenticaltoeachotheruntilthesequentialimpositionofsewertransientsat14and16s.Notethatthe\nsurchargeinpipe1doesnotaffectthesetrapsastheyareremotefromthebaseofstack1.Thetraponpipe20displaysaninitialreductioninpressureduetothedelayinappliedwaterdownflow.Thesewertransientinpipe19affectsthistrapataround18s.Asaresultofthepressuretransientsarrivingateachtrapduringthesimulationtherewillbealossoftrapsealwater.Thisoveralleffectresultsineachtrapdisplayinganindividualwatersealretentionthatdependsentirelyontheusageofthenetwork.Trap2retains32mmwatersealwhiletraps7and15retain33mm.Trap20isreducedto26mmwaterseal.Notethatthetrapsonpipes7and15wereexposedtothesamelevelsoftransientpressuredespitethetimedifferenceinarrivalofthesewertransients.Fig.11(a)and(b)illustratetheoscillationsofthetrapsealcolumnasaresultofthesolutionofthetrapsealboundarycondition,Eq.(10),withtheappropriateC+characteristic.Thisboundaryconditionsolutioncontinuallymonitorsthewaterlossfromthetrapandattheendoftheeventyieldsatrapsealretentionvalue.Intheexampleillustratedtheinitialtrapsealvaluesweretakenas50mmofwater,commonforappliancessuchasw.c.'sandsinks.10.Conclusion—viabilityofasealedbuildingdrainageandventsystemThesimulationpresentedconfirmsthatasealedbuildingdrainagesystemutilizingactivetransientcontrolwouldbeaviabledesignoption.Asealedbuildingdrainagesystemwouldofferthefollowingadvantages:•Systemsecuritywouldbeimmeasurablyenhancedasallhigh-levelopensystemterminationswouldberedundant.•Systemcomplexitywouldbereducedwhilesystempredictabilitywouldincrease.•Spaceandmaterialsavingswouldbeachievedwithintheconstructionphaseofanyinstallation.ThesebenefitswouldberealizedprovidedthatactivetransientcontrolandsuppressionwasincorporatedintothedesignintheformofbothAAVtosuppressnegativetransientsandvariablevolumecontainmentdevices(PAPA)tocontrolpositivetransients.Thediversityinherentintheoperationofbothbuildingdrainageandventsystemsandthesewersconnectedtothebuildinghavearoleinprovidinginterconnectedreliefpathsaspartofthesystemsolution.Themethodofcharacteristicsbasedfinitedifferencesimulationpresentedhasprovidedoutputconsistentwithexpectationsfortheoperationofthesealedsystemstudied.Theaccuracyofthesimulationinotherrecentapplications,includingtheaccuratecorroborationoftheSARSspreadmechanismwithintheAmoyGardenscomplexinHongKongin2003,providesaconfidencelevelintheresultspresented.\nDuetotherandommodeofoperationofbuildingdrainageandventsystemsfurthersimulations,laboratoryandsiteinvestigationswillbeundertakentoensurethattheconceptiswhollyviable.\n中文译文：密封的建筑排水系统和通气系统——活性气压的瞬变控制和抑制摘要由于通过成对的吸气阀和正压衰减器与管网中的立管互相连接能控制和抑制活性气压瞬变，因此在综合楼中采用密封的建筑排水系统和通气系统被认为是一个可行的提议。文章通过四根立管提出一种模拟实验，说明了瞬时产生和加强的气压在排水管中的流动机制。这种模拟实验在水封不被破坏，系统压力得以维持的条件下，能够辨认活性气压控制设备的作用。系统安全性提高、可靠性增加且设施和材料费减少，可见这种最初结果是令人高度鼓舞的，且足以证实潜在的明确利益，但进一步的模拟实验有必要提供概念上的证明，且它与其他以检验为目的的实验室、可能的地方、试验相比是有利的。关键词：活性气压控制，存水弯保持，瞬变传播。命名原则C+-——特征方程c——波速,m/sD——分支或堆积直径,mf——摩擦因子，英国定义通过DarcyΔh=4fLu2/2Dgg——重力加速度,m/s2K——损失系数L——管长,mp——压力,N/m2t——时间,su——空气速度,m/sx——距离,mγ——比热率Δh——水头损失,mΔp——压力差,N/m2Δt——时间间隔,s\nρ——密度,kg/m3目录命名原则1.介绍――瞬时气压的控制和抑制2.多立管建筑排水管网中的瞬时气压传播模拟实验的教学依据。3.系统运行差异的作用4.一个密封的多立管建筑排水个同时系统的郧西模拟实验5.模拟实验的规定6．排入管网的水7．立管1底部排水8．瞬时气压强加于污水管9．水封的振动和保持10.结论——密封建筑排水和通气系统的可行性1.介绍――瞬时气压的控制和抑制作为系统操作的自然结果，建筑排水系统和通气系统内部产生的气压瞬变对于水封破坏和交叉污染的可居住空间来说也是可靠的。[1]水封保护的传统模式，基于维多利亚女王时代的工程师对气味排除的观念[2]、[3]和[4]，通过交叉连接和立管排入大气[5]和[6]，主要取决于信任基础上的消极的解决方法。这种方法尽管既被证明了，也是传统的，但也有其内在弱点，如通气管末端较远[7]，导致了综合楼缓解反应到达较迟和敞开屋面立管末端内在的多样性。复杂的通气系统需要大量费用且于空间有密切联系[8]。在过去20年里，吸气阀（AAVs）的发展给设计师提供了一种缓解瞬时负压的方法，如在随机的洁具排水过程中，吸气阀有助于系统中水力条件的恢复。当吸气阀直接反映本地压力条件时，它们代表了一种控制活性气压的解决方法，它们自动打开，使新鲜空气进入管道系统，从而使系统的压力得到平衡并保护了冰封[9]。然而，吸气阀不能解决建筑排水系统和通气系统中瞬时正压传播的问题，污水管网中自由水流或远处产生的瞬时正压的到达通路间歇的关闭，有可能顺流进入一些其他的水——包括流入污水管的暴雨。\n正压衰减器[10]被开发用来吸收瞬时正压产生的气流，这种衰减器完成了必要的设备供应，为剧烈的瞬时气压的控制和抑制被采用到建筑排水系统和通气系统中做准备，这些建筑既包括一般性建筑也包括那些需特殊考虑的多种屋面、立管末端未封密的建筑。正压衰减器由大量可变量组成，这些可变量在瞬时正压的影响下不断扩充，从而为气流不断衰减做准备，因此产生的瞬时正压强度降低。吸气阀和正压衰减器设备共同使用被作为一个完全密封的建筑排水系统和通风系统的考虑因素。图1说明了吸气阀和正压衰减器设备，注意在负压条件下无水存水弯充当吸气阀。图1剧烈的瞬时气压控制设备控制正压和负压剧烈的瞬时气压的控制和抑制考虑到为保护水封对正压和负压偏移的局部调节。这种方法与传统的消极方法相比有明显的优点。它节约了等待瞬时气压从通气管排入大气使环节反映恢复的时间避免了在瞬时气压传播过程中对其他系统中水封的瞬时影响。2.多立管建筑排水管网中的瞬时气压传播模拟实验的教学依据。建筑排水和通气系统中瞬时气压的传播是可以理解和解决的问题，它可以通过StVenant方程式定义的非稳定流的连续性方程和动力方程来理解，可以通过有限的各种图表、利用特征方程的方法来解决。通气立管系统中下落的环形水和系统范围内的瞬时气压的反射和传播，包括未密封的通气管末端、污水管接头处、水封装置及AAV、PAPA控制装置都能带走空气，基于以上结果，系统中瞬时气压的产生和传播可以被准确模拟。这种模拟实验[11]提供当地的气压、速度和光速数据，贯穿管网中的时间和距离间隔很小，仅为0.001s和300mm。另外，模拟实验模拟当地水封装置的振动和气压控制装置的运用，从而依据管网中气流生成数据并能识别系统的不足及可能导致的后果。当这一模拟实验已经完全生效时，它单独的证实了2003年厦门花园内SARS病毒的传播机理。这更进一步的证实了它的预言[12]。\n瞬时气压的传播依赖于系统条件的变化速率。大量的环形溢流管导致了排除气流的提高和系统压力的降低。排出气流的延迟导致瞬时正压产生。管网中外部水的进入同样也能传播瞬时正压和瞬时负压。有水立管中的环形水流带走一股气流，这是由于在环形水和空气核心表面之间建立的“无滑”条件和沿立管往下产生的预期的压力变化。由于空气经过排水分支结合点处形成的水幕时产生摩擦和影响，在立管入口上端气压低于大气压。在低湿度立管中，由于优先对气流施加牵引力，气压穿过立管底部的水幕，从而气压高于大气压。模拟非稳定流所采用的特征方法的价值在20世纪60年代第一次被正式承认[13]，杰克[14]这一关系进行定义，采用模拟实验模拟施加于排出气体的牵引力量。大量的实验数据允许对“伪摩擦因素”定义，这些因素适合在湿立管中应用，并能作用于环形水流空气排除核心界面，从而允许进行混合排出流，及其对排除空气影响的模拟。建筑排水系统和通气系统中的瞬时气压的传播是由StVenant的连续性方程和动力方程定义的。(1)(2)有限的解一旦通过特征方程转化为有限的各种关系式、方程式，这些半双曲线性的偏微分方程是经得起检验的。⑶－⑹，未来一个时间段结点处的连接条件至上、下段临近节点的现行条件，图2。图2：StVenant连续性方程和动力方程预计将气流速度和波速用X-T坐标表示出来.注：⊿x<1.0m，⊿t<0.003s当\n(4)时为C+特征：(3)当(6)时为C-特征：(5)波速C可用公式c=(γp/ρ)0.5.(7)求得。由于气压和密度的相互依赖，这些方程式与空气流速U和本地波速C有直接关系。本地压力可用下式计算(8)合适的方程式将气流或水封振动分界面与本地气压相关。水封的应用是特别重要的。水封中的水柱由于管网和气压空间的瞬时压差而振动，在任何时候，对U形存水弯水封中的水柱的运动方程都可以写成(9)需要认清的是在应用方面水柱可能上升，相反的在系统方面水柱不可能超越分管连接处的水面高度。英国规定水封设在75或50mm处，其他的国际规范以设备型号为依据。水封保留值因此被定义为低于初始值的一个深度。许多规范意识到水封自然瞬变的破坏，容许水封破坏25％的机会。界限方程也可能由本地条件决定：吸气阀开启和随后的损失系数依赖于本地的预测压力。\n经验数据识别吸气阀开启压力，它的损失系数由开启过程和完全开启条件决定。水封装置的振动依据本地压力被作为一个界限条件来对待。弯曲的水封允许一般气流排入或排出装置或者水封转移导致的振动都可以被模拟。瞬时气压相互作用过程中导致的水封水量减少也被包括其中。3.系统运行差异的作用综合楼排水管网中运行系统将水排入管网，因此为气流排除和瞬时气压传播提供条件，这完全是随机的。任何时候根据它们的用法无法区别两个系统。如果综合楼管网中的个别立管是内部互联的，那么这种运行的差异意味着内立管通气路径将被确立。这种差异建议用来提供通气和对密封排水系统做出慎重考虑。为了完全成一个密封的建筑排水和通气系统，有必要使空气从一个安全空间而非从外界大气压进入管网，从而缓解瞬时负压。这通过吸气阀的使用或建筑内预先确定的位置可以达到，如易受影响的阁楼。类似的，用正压衰减器使瞬时正压减小是必要的。最初认为这是成问题的，因为正压能积聚在PAPA装置中，因此否认它们降低瞬时气流的能力。这个问题通过与综合楼中立管相连和利用建筑排水系统中内在差异可以再次避免，因为通过存水弯中空气经过相连立管通入污水管网可以保证PAPA气压自身进行缓解。这些差异也保护提议的密封系统不受无水管中的过大气压和瞬时正压破坏。综合楼将通过一些小的排水连接支管与污水干管相连。相反的气压条件将被分散，连接管网将继续提供通气渠道。通过一个多立管管网这些想法将得以证明。4.一个密封的多立管建筑排水和通风系统的运行模拟实验图3表明了一个四根立管的管网。四根立管通过对PAPA和AAV装置的多方面引导与高水平面相连接。在任何一根立管中向下流的水产生瞬时负压，关闭PAPA打开AAV使气流进入管网，排出污水管系统。既不是由于立管超负荷也不是由于污水管瞬时正压可以通过PAPA和对其他立管而言，允许立管-污水管途径充当会缓解途径的应用差异来降低。这个管网所说明的包括一个12m的总高度。在空气中声速为－330m/s时管网中的瞬时压力产生。这意味着从立管底到PAPA管道中历时大约为0.08s，从立管底到立管管底历时约0.15s.为简化模拟实验的输出，包括采用无水封的保护，如存水弯中无水，采用AAV和PAPA作为活跃控制。在独立通气立管处，传统管网将采用消极通气直接排入大气中，然而一个密封建筑可以采用这种通气方法。\n图3：用四根立管的建筑排水和通气系统来论证一个密封建筑系统的可行性。实际上四根污水管显示出的连接应该分开收集排水，以便污水管网中能进行自我通气。在综合楼中这种需要并不困难，而且在各种可能的条件下也是规范的。设想这些立管相互连接排入污水管网将会被分散并排入地下排水管中，使得下游管道直径增大。与管网的其他连接的所有可能性将是来自包括更传统的敞开通气系统设计的建筑，以至一个更深层次的差异被加到有持续时间较长的的额外水排入的下游污水分管上。类似的考虑导致了对住所的现行设计理念。必须强调的是管网中说明的是综合楼排水管网中是有代表性的。这中模拟实验将容许对一系列的排出装置和强加于污水管的瞬时条件进行调查研究。下列排出装置和强加于污水管的瞬变被考虑：⑴洗手间的水排入立管1-3历时1-6s,一个独立的洗手间排水进入立管4在2－7s之间。⑵连续贯穿模拟实验的水最小流速为0.1L/s，这是为了描述早期多种排水设施的水流。⑶在立管底部历时1s的超负荷事件假如发生在立管1中需2.5s。⑷依次加强于每根立管底部的连续的污水管瞬变从12－18s。这种模拟实验将论证控制活跃水位和实现密封系统中内立管通气两种想法的效果，即不存在高层屋顶渗透和建筑物外表敞开式通气立管。\n管网中强加的水流是基于世纪系统值之上的，根据最大流速2L/s，总流量6L/s和历时6s来说，现行的洗手间排水特征是具有代表性的。水标30mm处的污水管瞬变是具有代表性的但并不夸张。表1定义了W.C.排水和污水管压力的假定概况。表1排水和强加的污水管压力特征w.c.dischargecharacteristicImposedsewertransientatstackbaseTimeDischargeflowTimePressureSecondsl/sSecondsWatergauge(mm)Starttime0.0Starttime0.0+22.0+0.530.0+42.0+0.530.0+60.0+0.50.05.模拟实验的规定需要注意的是在各种情况下系统中立管的高度是从立管底部往上测量的。这意味着朝立管底部排除的气流为负压。从任以AAVs装置进入管网的气流将因此被指示为负压。从管网排入污水管连接处的气流也将是负压。从污水管连接处进入管网或沿立管向上引入的气流将是正压。然而沿直线下落的水的压力被认作为正压。遵守这些规定将会使接下来的模拟实验更好理解。6．排入管网的水表1以上所描述的W.C.排水，从1s到立管1-3和从2s到立管4是同步的。一根立管底部过载假定在立管1中为2.5－3s。因此从图4可以看出与预期的一样排除气流处于1、6和8号管中。然而，排入管网中的9号管中的气流是来自污水管。最初，尽管在19号管中仅有一股细流，由于气流已从管1、6和14中排出，管19中的排除气流被扭转，即沿立管往上，需在管1、6和14中对排出气流起作用。管12上的AAV也起作用但最初它需求的气流比例少且由于本地压力条件AAV振动。随着W.C.排水进入立管4，确定了2s前管19中的水向下流，由于下降的水在管上形成水薄膜而产生牵引力，使得反向气流一开始就逐渐减小。然而，在其他3根立管中\n产生的吸引力仍然导致在管19中产生一种持续的但减少了反向气流。3s前管19中的向下流达到最大值，管12上的AAV完全打开并且从这个来源增加的气流可能被识别。振动阶段被一个历时3.5－5.5s的完全开放期间代替。图4：通过排出装置带走气流随着W.C.排水进入立管4，确定了2s前管19中的水向下流，由于下降的水在管上形成水薄膜而产生牵引力，使得反向气流一开始就逐渐减小。然而，在其他3根立管中产生的吸引力仍然导致在管19中产生一种持续的但减少了反向气流。3s前管19中的向下流达到最大值，管12上的AAV完全打开并且从这个来源增加的气流可能被识别。振动阶段被一个历时3.5－5.5s的完全开放期间代替。图5说明了在2.5s时立管1和4的底部进入模拟实验的气体概况。立管4中的气压，表明与上面提到的反气流一致的压力梯度，立管1中的气压概况对于携带环形水流的立管是有代表性的，并且证明了由于立管底部水幕形成的正压。图5：立管1和4中的气压概况说明了管19中的反气压梯度。设置在管13上的最初容量是0.4L，最大扩充容量可达40L，然而它最初容量较小，此模拟实验阶段可能达不到。\n7．立管1底部排水图6说明了立管1底部的排水，管1从2.5s到3s，管1中排出的气流在立管底部将至0，并且图6中的立管中产生了瞬时气压。这个瞬时气压的影响将在后面对管网中水封的讨论中可以看到。图6：模拟实验阶段的W.C.排水期间管网中的气压水平。注意在立管1中的排水，在管1中为2.5s。从图6中也可以看出，管1、6和14中的预期压力，在不排水情况下，符合正常预期，即一股小的正压像排出空气一样，强行穿过立管底部的水幕进入污水管。就立管4，管19来说，进入立管的反气流证明了当它穿过存在于立管底部的水幕时气压下降。模拟实验允许立管1中的空气压力概况在图6所示的排水期间及之后被模仿。图7（a）和（b）表明了立管中从2.0s至3.0s时的气压概况，瞬时气压传播的增大和减小阶段连续产生。这一轨迹和压力振动说明瞬时正压沿立管传播，其中压力振动是来自管11上端的末端的AAV/PAPA连接点的瞬时气压的反射。8．瞬时气压强加于污水管表2表明在各立管底部一系列连续的污水管强加瞬时气压。图8证明了一种模式，即指出安装在管13上的PAPA和通过立管互联提供的自动通气的应用。因为正压被强加在管1底部12s，气流沿立管1网上被提升至PAPA连接处。然而，因为其他立管底部都没有被强加正压，因此在立管2－4中，第二气流通道被沿污水管连接点往下确定，就像图8中所示的负压气流一样。\n图7（a）：立管1中立管底部排水起始阶段的连续气压概况图7（b）：立管1中立管底部排水最终阶段的连续气压概况图8：强加于污水管的瞬时气压带走气流。因为强加瞬时气压减小所以反气流降低并且PAPA将空气排入管网，再一次论证了图8所示的模拟实验。如果各立管服从于污水管瞬时气压则重复这一模式。图9表明了立管1和2中的典型的气压概况。立管2中的气压梯度证实气流方向朝AAV/PAPA连接点沿立管往上。可以看出沿立管1往下气压继续下降，直至在管1和3\n中才恢复，这是由于这些管中持续不断的水流的影响。Fig.9.立管1和2中的气压概况PAPA安装通过吸收气流对污水管瞬时气压起反应，图10。PAPA将扩张直到积累空气达到假定的40L的容量。那时PAPA将加压并将通过不受强加的污水管瞬时气压影响的立管协助气流排出管网。需注意的是，当污水管瞬时气压被连续在立管1-4中应用时，这一现象被重复。高水平PAPA的容量，和其它的一起被引入一个更复杂的管网，能适应并保证没有系统增压发生。连续的瞬时气压的影响在各管网底部是可以认清的，因为PAPA容量在瞬是气压变化时减小，这是由于通过各立管中剩余的水流维持排出气流。9．水封的振动和保持存水弯装置和管网监测器相连，并对本地分支气压做出反映。这一模型提供了水封偏转和最终保持的模拟实验。图11(a)（b)描述了分别位于立管1和2上的存水弯的水封的振动。当气压在管网中下降时，存水弯中的水柱被转移以至位于水平面的装置下降。然而，系统的水面高度是由分支进口连接处的水平决定的，以致管网中水损失。这一影响在图11（a）和（b）中都有表明。管网中的瞬时气压条件导致水封振动，这仅能通过下个装置的使用来填充。如果瞬间影响严重那么存水弯中水可能完全耗尽以致在管网和可居住空间形成潜在的交叉污染路径。图11（a）和（b）表明了被强加的瞬时压力的末端的水封保持。\n图10：实验中的PAPA容量和AAV的过流量。图11（a）：水封振动，存水弯2（b）：水封振动，存水弯7图11（a）对管2上存水弯的描述，表明了当立管中气压下降时导致虹吸，存水弯中水进入管网。伴随立管1中的过流2s打断这一过程。伴随立管1中下流水的停止，存水弯振动减轻。通过在存水弯装置一边的水面的上升，污水管瞬时气压在12s的强加是显而易见的。如果存水弯系统一边的水面降至U型存水弯，更剧烈的瞬时气压在这一阶段可能导致“气泡穿透”。\n管17上的存水弯中的水封振动，图11（b）和15，是相同的，直到连续加强的污水管瞬时压力持续14s和16s。注意管1中的过流不影响那些存水弯，因为他们离立管1的底部很远。管20上的存水弯表明由于提供向下水流的耽误产生的最初的压力降低。管19中的污水管瞬时气压影响存水弯约达18s。在模拟实验中，作为瞬时气压到达各存水弯的结果是产生存水弯水头损失。这一全面的影响导致各存水弯显示为一个单独的水封保持，这完全依赖于管网的使用。存水弯20保留了32mm水封而存水弯7和15中水封33mm。存水弯20中的水封高度被降至26mm。注意管7和15上的存水弯遭受同一水平的瞬时气压，尽管在到达污水管瞬间有时间区别。图11（a）和（b）论证了水封中水柱的振动作为水封限制条件的结果，方程式（10）及相称的C+特征方程。这一限制条件的解不断的检测存水弯的水头损失及在存水弯最后的水封保留值。在这个例子中论证了最初的水封值被理解为50mm高，这，对于如W.C.中的各器具和厨房的洗涤槽是普遍适用的。10.结论——密封建筑排水和通气系统的可行性采用的模拟实验证实了密封的建筑排水系统中利用活跃瞬间控制是一个明智的设计选择。一个密封的建筑排水系统可以提供以下优点：•系统安全性无限提高，因此高层敞开系统末端将是多余的。•系统复杂性降低而系统的可预测性提高。•建造时期的任何设备的空间和材料都将得以节省。假如将抑制瞬时负压的吸气阀（AAV）和控制瞬时正压的正压衰减器结合应用到设计中，用于活跃瞬间控制和抑制，那么这些好处都将得以实现。作为系统解决的一部分，建筑排水和通气系统和与建筑相连的污水管操作的内在多样性起到提供互相连接的缓解途径的作用。基于现行的有限的各种模拟实验的特征，为精心安排的密封系统的操作提供了与期望值一致的数据输出。对其他新近设备的准确度模拟，包括对2003年在厦门花园和香港对病毒传播机制的准确正式，为现行结果提供了置信度。由于建筑排水和通气系统的随机运行模式，需要进行更深层次的模拟、实验和地方的调查研究，以确保这一构思完全可行。