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ProcedingsoftheCombustionInstitute，Volume29，202/p.267-272
THEROLEOFAFLAME-INDUCEDLIQUIDSURFACEWAVEON PULSATINGFLAMESPREAD
T.KONISHI，lA.ITO，2Y.KUDOU2ANDK.SAIT03
lDepa付mentofMechanicalEngineバηg OitaNationalColegeofTechnology Oita，]apan 2DepartmentofInteligentMachineandSystemEngiηering HirosakiUniversity
Hirosaki，]apan
3Dep凶 作U3ntofMechanicalEnginering UniversityofKentucky Lexington，KY40506，USA
Thedetailedtemperatures仕ucturethatwascreatedduringapulsatingflamespreadovern-butanolwas measuredusingholog勾 hicinterferometer，shadowgraph，andIRthermographtechniques.Thisstudy found出此 therewasasmalsurfacewaveoverthepreviouslyobservedcold-temperaturevaleylocated about10mmaheadofthespreading:8.ame'sleadingedge.Thenewlyobservedsurfacewavewaslocated betwenthespreadingflameedgeandthecold-temperaturevaley.Thecrestofthewavewashigherthan 也equenching占stanceofthespreadingflame.Duetotheformationofasmalgas-phasecirculationcel 也此 wasobservedtoexistbetwenthewavecrestandtheflameleadingedgebylasershetp訂 ticle 廿ackingandsmoke-tracingtechniques，the:8.ammablegasmixturecanotspreadbeyondthewavecrest; therefore，theflame'sleadingedgewasnotabletopropagatebeyondthewavecrest.Thecrawlingspread proceswasbelievedtobeaspreadproceswi也 constantsped，but出isstudyfound也atitconsistsofa smal-scalepulsation(subpulsatio叫 wi也 6-12Hzfrequency.Subpulsationsemslikelytohaveacore- la世onwiththecyclicapearanceanddisapearanceofasmalgas-phasecirculationcel出attravelsbe- twenthe丑ameedgeandthewavecrest.Whenthecrawlingprocesprovidedsuficientheatto血eliquid， thecold-temperaturevaley占sapeared.ThenthewarInliquidhelpedtoforma:8.ammablegaslayerover itssurface，enablingtheflametopropagatethroughthelayer.Thisiscaledthe“main"pulsa世ngspread， atypicalyobservedpulsating:8.ameιspreadphenomenon.Thisstudyrevealedthatamilimeter-ordersur- facewaveisresponsibleforthesubpulsation出atisresponsibleforthemainpulsatingspread.However， themechanismofsurfacewaveformationisunknownatthistime.
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Introduction
Inthisstud予 wefocusonadvancingour1mow1- edgethroughexperimentalobservationandmea- surementsofthepu1satingflamespreadoverη-bu- tano.lTheres叫tsofthisstudywil1meritnumerical studies吐lathavebeencariedoutbyotherresearch- ers[1-3]，whohavemadegoodcontributionstoun- derstandingthemechanismofflamespreadoverliq- uids.
spread，itiscrucialtoobtaindetai1edthermal，丑uid dynamic，andchemicalstructuresofbothgasand liquidphasesneartheflame1eadingedgeduringthe flame-spreadproces.Inourpreviousstudies[8刻， therefore，we aplied six diferent experimental techniques，including1asershetparticletracking， smoke tracing，sing1e anddualwave1engthho1o- graphicinterferometers(HIs)，IRtherm6graph，and high-spedphotographytomeasuredetailedtran- sientthre-dimensionalflow，temperature，andfue1 speciesconcentrationprofilescreatedbyapu1sating spreadoverpropano.l
Fivediferentprocesesonthepulsatingspread ぽ eidentifiedinourpreviouspaper[8，9]:(1)出e onsetofp叫sation，(2)也eformationofacold-tem- peraturevaleyintheliquid，(3)thedisapearance oftheco1d-temperaturevaleyandtheformationof aflammab1egaslayerover也eliquidsurface，(4)a flamejumpthroughtheflammablegaslayer，and(5) atemporalcesationofthE(spreadconectingback
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