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SURFACEWAVEONPULSATINGFLAMESPREAD 271 60
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Time(sec)
FIG.6，Horizontal占stancebetwentheflameleading edgeandthewavecrest，d，andtheminimumtemperature oftheliquidcold-temperaturevaley，TLM，bo出 国 afunc- tionoftime(theplotisa0.2mmpoldepthcase;theother depthcasesalsoshowedasimilartrend)，Theinitialbutanol
temperaturewaschangedbetwenTo=17.3and20.8oC. asd)，asafunctionoftheinitialiquidtemperature
Opencirclescorespondtodandsolidcirclescorespond toTL M・
El;
86 g
t言 4
andoftimeduringtheflamepulsation.Thedetailed HLSG，andIRmeasurementsconcluded也atthe pulsa世ngflamespreadconsistedofthemainpulsa- tionandanewlyfoundsubpulsa世on.Thefrequency ofthemainpulsationwasaproximately1-2.Hz， whue也atofthesubp叫sationwasaproximately 6-12Hz.Ourexperimentsalsoconfirmedthatthere wasastrongcorelationbetweenthefrequencyof oscilationofdandTLM' Toimprovethecurent flamespread也eory[21J也atusesarathergeneral characteristiclength，thisstudysugestsdcanbea morespecificparametertodescribeflamespread over 凶 ds. combinedwith
5 2i;ljr
liq Scalinganalysis further experimentalstudiesu山 gthealreadyestablished experimental techniques [8，9 and 也 is study] wil l helpfindakeypi-number(ornumbers)thatcontrols 也epulsatingflamespread.
40 FIG.7.Themaximum占stancedasafunctionofthe
g initialbutanoltempe1'ature.
Acknowledgments
Tl由 study was sponsored by the Kentucky-NASA EPSCoRprogram.Weac1mowledgeH.Ros，F.Miler，and T.Hiranofo1' theirvaluablecomentsonflamespread overliquids.
REFERENCES
l. Schil ler，D.N.，Ros s，H.D.，andSirignaro，W.A.，AlAA paper93-0285.
2，Schiler，D.N.，Ros，H.D.，andSirignaro，W.A.，Com- bust.Sci.Technol.18:203(196).
3.Schiler，D.N.，andSirignano，W.A.， Proc.Combust. Inst.26:1319-1325(196).
4.Akita，K.， Proc.Combust.Inst..14:1075-1083(1972). 5.Glasman，.1 andDryer，F.，FireSafety.J.3:123-138
(1981).
6. R o s s ， H . D . ， P r o g . E n e r g y C o m b u s t . S c i . 2 0 : 1 7 - 6 3
(194).
7.Hirano，T.， andSuzuki，K.， Prog.EnergyCombust.Sci.
20:461-485(195).
smaliquidsurfacewave，d，andtheminimum~em­ per拭 ure at the cold temperature val ley，TL M ' The distancedislesthan6m mduringthesubpulsation proces，andthecrawling(themainpulsating)宜ame didnotspreadbeyondthesmalsurfacewavecrest， whoseheightis0.9mm.Thereisapa仕eminthe oscilationofdandTL M:thefrequencyofoscila世on ofdisaproximately5-10Hz，whichagreswiththe oscila世onfrequencyofTLM'Thisindicatesthatthe formationofthecold-temperaturevaleyandthe smaliquidsurfacewavearecoupled.
Figure7showsthemaximumdistancedasa五mc- tionoftheinitialbutanoltemperature;itshows出at themaximumdcontinualydecreaseswithanin- creaseoftheinitialbutanoltemperatureandisex- pectedtobecomezeroattheflash-pointtempera- t u r e . F i g . 7 s u g g e s t s t h a t a c r i 世 c a l d c ， e x i s t s : w h e n themaximumdislargerthandc，theflamespread becomespulsating，whilewhenthemaximumdis smalerthandc'出eflamespreadbecomesuniform.
Omlclusions
Wefoundasmaliquidsurfacewavecreateddur- ingpulsatingflamespreadoverbutano.lThesurface wavealwaysexistedjustaheadoftheflameleading edgewhentheflameexhibitedpulsa世on.Wecare目 fulymeasured出edistancebetweentheflamelead- ingedgeandthecrestofthesurfacewave(defined