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concentrationexceededtheleanflammablelimit.Fig.8showsrep- resentativedatafromA-8(thepositionnearestthefueltankholes incompartmentA).B-2(thepositionnearestthebateryterminal incompartmentB).じ 5(thepositionnearestthepartitionholein compartment仁).and0-6(thepositionnearestthepartitionhole incompartment0).Time(horizontalaxis)indicatestheelapsedtime afterthefueltankwasplacedinthemock-up.Thevaporconcentra- tion(verticalaxis)isexpresedasapercentageoftheleanflammable limit.Forgasoline.theleanflammablelimitis1.2vol%.whichcore- spondsto100LFL克.andtheupperlimitis7.3vol%.whichcore- spondsto600LFL克.Plotingaldataonalogarithmicscale.the concentrationcurvesmakestraightlinesversustheelapsedtime. Ifthestraightlineisextrapolated.thetimetoreachtheupperlimit canbepredicted.Thetravelofgasolinevaporcanbepredictedby therelationshipoftheconcentrationvaluesineachcompartment. ThegasolineleakedfromthegasolinetankincompartmentA.diι fusedtocompartmentBandC.andfinalyreachedcompartment O.AtcompartmentB.whichcontainedthebatery.andinC.on
whichthepasengerssat.aflammablemixtureofgasolinevapor andairwasmaintainedfromthe1.7thdaytothe175thdayfrom thedayafterplacementofthefiledandleakingfueltank.Therefore. duringthisperiod.compartmentsBand仁 werealwaysexposedto thedangerofexplosion.whichmightreadilyhavebeentrigered byasourceofignition.IncompartmentO.flammableconditions weremaintainedbetweenthe3.3rddayandthe83rdday.
After the concentration measurements were completed. we foundthatatraceofthefueleakageremainedinthewoodsurface aroundthefueltank.Leakageoffuelwasfoundaroundrustywelds inthelowerpartofthefueltank.Ouringtheexperiment.the amountoffuelleakagewasestimatedtobe190cin3days.
4.3.Ignitionofgasolinevaporandflamepropagationbetwenlinlad compartrηents
Thelasteforttodispelsomeofthemysteriesintheboatexplo- sionwasperformedbyusingthelinkedvesels.The“presure
工 Konishieta.ljS日ifetyScience53(2013)73-81 77
Fig.9.Photographsoftheignitionandflamepropagationphenomenaduringthecourseoftheexplosioninthesmalトscalecombustionchamberat:(a)0ms，(b)4.2ms，(c) 12.5ms，(d)20.8，(e)25.0，(f)29之 (g)33，3. and(h)37.5msafterignition.