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heatdistancemuchfartheraheadoftheflame，carieswarmliq- uiddeperintothepolandhashigherrotationalvelocitiesthan innormalgravity.
Figure8presentsthermographicimageshowingliquidsur- facetemperatureaheadoftheflameinμgandsteadyspreadwith largeregionofasymetricalpreheatedfluid(RosandMiler，
196b).WhileFig.7(b)showssteadilyflamespreadinpseudo- uniformregimein1g.Theμgflameshowsasimilarliquidsur- facetemperaturestructuretothatof19pseudo-uniformf1ame， composedoflarger，asymetricalcur1saheadoftheflame.Note thatthelowtemperatureregionjustaheadofflameedgecanbe observedinboththermographicpictures.Wec1arifiedinprevi- oussectionsthatthistemperaturevaleyalwaysprocedsin企ont offlameedgeinpseudo-uniformregimeandcausesforslow steadyflamespread.Thesimilarityofsurfacetemperaturestruc- turebetwenμgand19flamededucesthatthesamemechanism causesfortheμguniformspreadphenomenon.
Now，wehavesti1ltwomorequestions;thefirstis“whynot thetemperatureliquidisheatedoverflashpoint".Wesuposed thatasthefueltemperatureislowenoughinpseudo-unifornre- gion，heattransferprocescanotrisethefueltemperaturebe- yondflashpoin.tOntheotherhand，theinitialfueltemperature oftheμgexperimentsisnotquitelowenough.羽市atcausesfor thecontinuousexistenceofthelowtemperatureregion?Thelack ofbuoyancyefectseemtooriginateinp紅t.Asthetemperature stratificationinliquid-phasecanbelesenedbytheefectofbuoy- ancyforce，inhomogeneityofsurfacetemperaturedistribution preferstocontinuewithoutbuoyancy.
Thesecondquestionis“howdidthediscrepanciesbetwen thenumericalandtheμgexperimentalresultcreate".Asdescribed before，thelowtemperatureliquidcomesup企omthebotomof thefueltraybythehelpsofthermocapil1aryandbuoyancyforce inliquid-phase.Andthen，theliquidexposesathre~-dimensional natureinthefueltray.Thus，thelackofbuoyancyandthre-di- mensional.e百ectwouldcausethedisagrement.Thebuoyancy e百'ectsemsnottoworkwithveryshalowliquidcontainerused inhismode.lIfthemodelextendsthecomputationaldomainof 1iquid-phasetoarealisticdepthof10mmandtothre-dimen- sionalequations，morepracticalresultswouldbeobtained.
CONCLUSION Thephenomenologyofpulsatingandpseudo-unifOlm spread
wereexaminedthroughexperimentaldeterminationofsurface temperat:ureandconcentrationprofiles.Thefolowingconc1u- sionarededuced:
(1)百leliquidconvectionisakeycontributortobothpulsat- ingandpseudo-uniformmechanism.Themeasurementofsur- facetemperatureverifiedthetemperaturevaleyalwaysproceded tospreadingflameincrawlingportionofpulsatingcyc1eand pseudo-uniformregime.Thiscoldareac1earlyobstructscrawl- ingflamefromshiftingtojumpingstage.Becausethesurface temperatureinthisareaisbelowflashpoint，su伍 cientfuelvapor canotacumulateaheadofflameedgeinspiteofexistenceof gas-recirculationcell.Thejumpingportionofpulsationcycle ocursafterthetemperaturevaleydisapearsandflammable vaporlayerisgeneratedduetoheattransferfromliquid-andgas- phase.
(2)百leresultsofvaporconcentrationprofilespreviouslymea-
suredbydualwavelengthholographicinterferometry(DWHI) areguarantedbythemeasurementsofsurfacetemperatureus- inganinfraredcamera.Incrawlingphaseofpulsatingregime， theexistenceoftemperaturevaleyprovednosuficientflam- mablevaporwasexistedjustaheadofflameleadingedge，which wasalsorevealedbyDWHI.
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