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1、15thAustralasianFluidMechanicsConferenceTheUniversityofSydneySydneyAustralia13-17December2004FireBehaviourStudiesofCombustibleWallLiningsApplyingFireDynamicsSimulatorA.Z.MoghaddamK.MoinuddinI.R.ThomasI.D.BennettsandM.CultonCentreforEnvironmentalSafetyandRiskEngineeringVictoriaUniversityofTechnologyP
2、.O.Box14428MelbourneCityMCVictoria8001AustraliaVisitingResearchFellowTarbiatModarresUniversityTehranIranAbstractInthispapertheresultsofalargeeddysimulationofanISO9705roomcornerfirearepresented.ThefieldmodelFireDynamicsSimulator(FDS)wasusedtostudythecornerfirewithandwithoutcombustiblewalllinings.Comp
3、arisonoftheresultsfromsimulationswithprescribedheatingandpublishedexperimentsshowedthatwith50mmgridspacingitispossibletoquiteaccuratelyreproducetheexperimentaltemperaturedatalocationsinsidetheroom.WhenacombustiblewallliningisincludedaT-shapedflamepatternsimilartothatobservedintheexperimentalstudywas
4、obtainedbutonlywithaparticulargridsizeandreactionmodel.Inconsistentresultswereobtainedwithvaryinggridsizesandreactionmodelswhencombustiblewallliningtestsweremodelled.IntroductionFiremodellingisahighlydesirabletoolforfiresafetydesignengineers.SincetheintroductionoftheearlyversionofFDSin2000withitsrel
5、ativelyaccuratepool-firesimulationresultsandfreeaccessibilityviatheNISTwebsiteithasfoundwidespreadapplicationsinfireengineeringdesignandresearch.FDSisacomputationalfluiddynamics(CFD)modeloffiredrivenflowandadetaileddescriptionofthemodelisprovidedintheFDSmanualandalsobyothers1-3.FDSapplicationsreport
6、edintheliteraturearealmostexclusivelyaimedatverificationofFDSresultswithexperimentaldatausingasinglefuelusuallycomprisingtheburningofaliquidfuelinpoolorgasfromaburner.ForISO9705roomcornerfirescenariosFDShasonlybeenappliedtoasandburnerwithpropane4nottoaliquidpoolfire.Moreovertothebestofourknowledgeno
7、reportontheapplicationofFDSultiplefuelscenarioshasbeenpublished.InthisworktwoseparateFDSsimulationsoftheISOroomwithaliquidfuelfirewereconducted.Thefirstsimulationinvolvesatrayofmethylatedspirit(consistingof93%ofethanoland7%ofmethanol)asacornerfiresourceinordertodevelopbaselinedataforthelaterISOrooms
8、imulationswithcombustiblewalllinings.Itisreferredtohereinasthepoolfire.ItisnecessarytosuccessfullyreproducethepoolfireexperimentalresultstothenbeabletocarryoutsuccessfulFDScalculationsofthesameroomwithcombustiblewalllinings.Inthesecondsimulationmethylatedspiritwasthesource-firefuelandplywoodaswallli
9、ningswasthemainfuel.Theoutputsofbothsimulationsarecomparedwiththeexperimentalresults5.InFDSwhentwotypesoffuelareinvolvedthespecificationofthegoverningcombustionreactionneedstobeconsideredverycarefully.TheFDSpackageincludesSmokeviewagraphicalprogramthatallowsvisualobservationoftheFDSresults.Inroomlin
10、ingfiresimulationsduetotheavailabilityofthelargecombustiblesurfaceareaitispossibletoobservefromSmokeviewanimationstheimportantstagesoffiredevelopmentincludingtheflamespreadpatterntheapproachofflashoverandthepostflashoverstage.TheseobservationsproviduableinationonthepredictionabilityofFDS.Experimenta
11、lworkTheexperimentaldatausedherearefrompreviousworkcarriedoutattheFireSERTCentreUniversityofUlster5.Hereonlyabriefsummaryofthetestisprovided.TheexperimentswereconductedinanISO9705roomthewestwallofwhichwasmodifiedtoincludethreewindowswhichenabledadirectviewofthenorthandeastwall.Double-glazingwasemplo
12、yedtoensuretheintegrityoftheenclosureboundarywasmaintaineduptoandbeyondflashoverthusfacilitatingobservationandvideorecording.Theremainingenclosurewallsandtheceilingconsistedofmasonryconstructionandwerelinedinternallywith15mmthickceramicfibreinsulatingboard.Thefloorsurfacewascoveredwithconcreteblocks
13、.Theprimaryfuelsourceusedwasa0.55m0.55m0.1mdeeppoolofmethylatedspiritlocatedinthenortheastcorneroftheroomandplaced0.4mabovethefloorand0.05mawayfrombothwalls.Foreachtest8kgofmethylatedspiritwasused.2.4m3.6m2.4mExhaustgasesExhausthood3mx3mx1mTC-PTC1TC2TC-MTC4TC3TC-CNTC-DFigure1.SchematicdiagramofISO97
14、05firetestroomAdoorway2mhigh0.8mwidewaslocatedatthecentreofthesouthwall.Thedoorwaywasfullyopeninalltestsprovidingfreepassageofenteringairandtheoutgoingproductsofcombustionwhichwerethencollectedbyanexhausthoodanddirectedtoanoxygenanalysingsystem.GastemperaturesweremeasuredusingtypeKthermocouples.Sixt
15、hermocoupleswereplacedontheceilingonedirectlyabovetheburnertorecordplumetemperatureanotherinthecentreoftheceilingwiththeremainingfourwerelocatedsymmetricallyaroundthiscentralthermocoupleasshowninfigure1.Athermocoupletreeconsistingoftenthermocoupleswaslocatedinthemiddleofthedoorway.Anotherthermocoupl
16、etreewasplacedinsidetheroominthesouthwestcornerinaccordancewiththeISOstandardtomeasurethevariationoftemperaturewithheightoff-the-floor6.Toallowvisualobservationofsurfaceflameandchardevelopmentlinesweredrawnhorizontallyandverticallyontheeastandnorthwallcombustibleliningsurfaceat0.2mspacing.Priortothemainliningtestaseriesofpool-firetestswereconductedtodeterminetheHRRfromthepoolfire.OverviewofFDSSimulationForthecurrentFDSsimulationtheLESofcalculationisused.Thisusesamixturefractioncombu
