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smalpolfire.Basedon白atexperience，weapliedtheLSPT techniquetomeasureatimeseriesofdetailedvelocitypro血esin 出epulsatingspreadregioriandsucesfulyconfirned白 forna- tionofasmalcirculationinaproximately血esamelocationas predictedbytheUC1numericalmodel(SchilerandSirignano， 192).Wealsoconfirned，inagrernentwiththemodelprediction， 出atthefornationofasmalcirculationapearsonly也 出e pulsatingspreadregion.
ExperimentalApparatusandProeedures Flame-SpreadAparatus. TheFlame司 spreadap紅 a加 s(fjg.
1)usedfor出isstudyisesentialythesarneasthatus~d ina previous:flame-spreadstudies(Ito，Masuda，佃dSaito，191;1to， Saito，姐dCremers，195;andTashtoush，Narumi，Ito，Saito，姐d Cremers，196).APyrextrayof2-cmwideX 2.5-crndepX 25-cmlongwasused.百letwolongsidesofthefuel町aywere madeofPyrexof0.2・cm也icknes.τ'heentireliquid位aywas enclosedinaglascel，14-cmhighX 15-cmwideX 35-cmlong， tomiD.im:izelaboratorydraftandprovidearepeatableftarne-spread condition.Thetemperatureoffuelwasmeasuredbyplacinga chromel':'alumelthernocouplewith75-μmwirediameter白atwas placedatthecenterof血e仕ay2mrnbelowthefu61surface.The tempera佃 reofarnbientairwasmeasuredneartheglassidewal bythesametypeofthethermocoupleusedintheabove.An ejector-noz zle was added to the previously developed particle feder(Venkatesh.，1to，Saito，andWichman，196)so出attalc partic1escoulduniform1ydisperseovertheliquidsurface.The u凶fom註tyofpartic1edis住ibutionwascheckedvisualy.Anin企a- red(IR)ca立leraandthermalirnagingsystem出atweredeveloped duringourpreviousupw訂 dftame-spreadexperiments(Qian， Ishida，and Saito，194) were aplied to measure the two回 出mensi∞altemporalmapof出eliquid-surfacetemperature.A Sonyvideocarnerawasusedtorecordtheentireft釦 le-spread proces.
Table2 Uncertain，句 estimatesforD w m
194;andMilerandRos，192)andourpreviousexperiments (1to，Masuda，andSaito，191;Ito，Saito，andCremers，195;釦 d Tashtoush，Narumi，1to，Saito，andCremers，196)，l-propanol wasusedasfue.1τ'hefuelwasuniformlyignitedatoneendbya smalpilot自白ne.l五gh-presurenitrogenwassupliedfroma ni仕ogencylindertoextinguish出eft釘 ne.
Velocity Measurement With LSPT and Visualization of Flame-Induced Air Flow With a Smoke-Trace Technique (ST). Fromourpreviouss旬dies(Qian，Ishida，組dSaito，194; andHirano叩 dSaito，195)，welearn<?d也ataLSPTteclu向ue withahigh-spedvideocarnera(50企arnes/swithashutersped of0.2ms)bestsservedourpu甲 ose.Wi出 significantlyfewer particles，theLSPTcanmeasure'two-dimensionalprofilesofboth stream1inesandvelocitysimultaneously.A high-spedcamera withanultravioletlensandanimageintensifierwasusedtoobtain 出 e velocity ofpartic1es with 50 0 企 ames/s spe ed. Usi
Table1 UncertaintyestimatesforLSPT Lasershetthlcknes negligible
IdmisacgretEpnmescsesing 6%
preclS10n
Tim巴 negligible
T口凶l 6%
Lasershetthlcknes negligible
IdmisacgmeteprI∞ESesizlE 6% bi岱
T卸1e negligible To阻1 6%
(ST)wasapliedtovisualizetheoverals仕uctureofftarne- inducedairftowinthegasphaseandliquidconvectionin吐le liquidphasesirnultaneously.τ'beglascontainerenclosingthe ftame-spreadtraywasfiledwithincensesmoke.百le位aywas filedwi出 1-propanolandthefuelwassededwiththesmal aluminump釘 ticlesasusedfortheearlierLSPTmeasurements. Afteraunifornsmokelayerwasfonedabovetheliquidsurface 出efuelwasignited.
DualWavelengthHolographicInterferometry(DV¥守町. 百 lebasicprinciplesbehindDWHIarethesameasthoseforthe singleHI(lto，Masuda，担dSaito，191;Ito，Saito，andCremers， 195;andTashtoush，Narumi，Ito，Saito，andCremers，196).A schematicofDWIDisshowninFig.2.D'¥在丑 'isanindirect measurementtechniquewitharesponsetimeofles也叩 arucro司 secondandaspatialresolutionofles血 血 土 0.1m minidentiちring concentration di首 位 ence. The D W H I has significant advantages overthemicro-samplingtechnique(Saito，Wiliarns，andGordon， 1986)，whichhasaspatialresolutionofseveralruli皿 etersanda responsetime血atisatbestontheorderofasecond.Inadition， themicro-samplingisadirectgassamplingtechnique也atwil causealargephysicaldisturbanceintheftowfield.
Westartusingatwo-dimensionalmodelofDWHI泊 thepresent study and experimental ly detemlIned .the best pos sible two- dimensionalconditionforthemeasurement.Thebasicprinciples ofDWHIaredetailedi
(2) MAY1999，Vo.l121 I415
Uncertainty Total Journal01Heatτransfer
8.5%
precJsJon
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WavelengUl Fringeshiftnumber Pathlength fuelvapordensity Gladstonc-Daleconstant Molecularweight To凶I
WavelengUl Fringeshiftnumber Pa出leng出 fuelvapordensity Gladstone-Daleconstant Molecularweight Total
negligible 5% negligibl巴 negligible n巴gligible negligiblc 5% negligibl巴 negligible 15%
2% negligible negligible 15.1% 15.8%
Uncertainty To凶l
anglewasestablished(Fig.1)andguidedbyanoptical節 目 to出e placewherethemeasurementwastobedone.
Velocityprofilesoftheliquidandgasconvectionweremea- .suredindependentlyusingLSPT.Forthemeasurementofgas-
phaseconvection，talcpartic1esweredisperseduniformlyabove 出e釦elsurface.Forthemeasurementofliquidconvection，alu- minump訂 ticlesof15(:!:5)μmdiameterweresprinkledonto也e liquidsurface.Some'a1urninump紅丘c1esfloatedon白色 liquid surface組 dothersenteredinto吐leliquid.Thealuminumpartic1es usedeachweighedles出 回 0.01gra皿 ssothat出βpartic1eshad litlee百'ectonthefuelproperties.
The回 dectoriesofthesepartic1eswererecordedbyahigh-sped videocamera出atwasconectedtoavideosystemandaTV monitorforthereal-tirneobservationofboth:flowfieldandspread- ingftame.1nordertoconstructasingletwo-dimensionalftow- vectordiagrambycombiningtheindependentlyobtainedgas-
Tocomp紅 eourdatawithNASA'smicrogravitydata(Ros， ph出 eLSPT担 dliquid同 phaseLSPT，asmoke-仕acetechnique
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