Page 100 - konishipaper
P. 100
Proceeding01ihe 5thASME/JSMEJointThermalEngineeringConference March15~19， 1999，SanDiego，California
9回 6315 丁目 EMEASUREMENTOFSURFACETEMPERATUREANDVAPORCONCEN11RA1rION
PROFILESFORASPREADINGFLAMEOVERLIQUIDFUlElS
Akihil(oIto TadashiKonishi Dep.tofProductionSystemsEng. Dep.tofProductionSystemsEng.
AldraNarumi Dep.tofMechanicalEng. KanagawaInstituteofTechnology Atugi，Kanagawa，243-02
narumi@me.kanagawa-i.tac.jp ClifordCremers
Dep.tofMechanicalEnginering UniversityofKentucky
OitaUniversitysity Oita，870・1192，Japan aito@oita-u.c.ac.jp
GhassanTashtoush Dep.tofMechanicalEnginering UniversityofKentucky
.OitaUniversitysity Oita，870-1192，Japan konishi@oita開 c.tac.jp
KozoSelito Dep.tofMechanicalEnginering UniversityofKentucky
Lexington，Kentucky40506，USA Lexington，Kentucky40506，USA Lexington，Kentucky40506，.USA gmtashOO@pop.engr.uky.edu saito@engr.ukドedu
Keywards;fire，flamespread，liquidfuel，surfacetemperature，vaporconcentration
ABSTRACT
Longcontroversialdiscusionsonmechanismofpulsating flamespreadoverliquidfuelshasbencontinuedsince1970's. Thispapermightputanendtothisproblem.Mainly，twohypoth- esishasbeenproposed00mechanismofpulsatiogflamespread， oneis"theformationanddestructionofare-circulationcelingas phase"，theotheris"theformationoff1ammablevaporlayerdue tohotsurfacetensionf1ow".Recently，experimentsinmicro-grav同 ityrevealedthatinspiteofarecirculationcel1ingasphasewhich existedinfrontoff1ameedge，nopulsationocurs.1nstead，slow pseudo-unifornspreadbasbenobservedinn-butanoldeppoo.l Tbisfactarisethenewproblems，whicharetheroleofliquidphase buoyancyandthre-dimensiona1efectofbothgasexpansionand surfacetensionf1ow.
1nourpreviousstudies，wemeasuredthedetailedvelocityand fuelconcentrationprofilesinan-propanolpolbyusingpartic1e trackvelocimetryanddualwavelengthholographicinterferom- etry，respectively.Then，wefirstsucedtomeasureaseriesof detailedvelocityandvaporconcentrationprofilesinpulsatingre- gime，whichconsistsoffivestages，(a)onsetofpulsating，(b)de- velopmentofsurfacetensionflow，(c)formationofrecirculation f1ow，(d)jumping，and(e)endofpulsating.
.Thispaperfocusedonobtainingdetailedmeasurementsof fuelsurfacetemperatureprofilesbyusinginfraredcameraineach pulsatingstage.Weusedbothn-propanolandn-butanolforfuels in2.5cm.depPyrexpool.Then，wefoundthatlowtemperature liquid;so-cal1ed"temperatureval!ey"，existsinfrontofpulsating flamefo1'bothfuelsasshowninFig.A-l.Thiscoldareaclear1y obstructcrawlingflamefromshiftingtojumpingstage，because
thesurfacetemperaturein出is訂 eaisbelowthet1ashpoint.The jumpingstageocursafterthe也mpera加 reval1eydisapearsand flamablevaporlayerisgeneratedduetoheatingbyout-com- ingf1ame.Theemergenceoftemperaturevaleyisderivedby theinteractionofsurfacetensionflowandbuoyancy.Thissug-
geststhatasthereisnobuoyancyefectinmicro-gravitycondi- tion，theflowfieldinliquidphaseandsubsequentsurfacetem- peraturemightbediferentwithnormal-gravitycondition.The resultsofdualwavelengthholographicinterferornetryconfI.lmed thatlowconcentrationregionexistsatseveralmi1limeterahead ofaf1~me leadingedge.
Thishypothesiscanalsoexplainphenomenologyofpseudo- uniformregion.Weobservedthatverylargetemper剖 urevaley， whichislargerthanthatofpulsatingf1ame，alwaysprocedsto spreadingf1ameinbothn-propanolandn-butanolpols.
FigureA-1Thermographicimageinpulsatingstep[b].
Copyright@ 19byASME
