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Propanolwassued出 向el，.sinceitproviclesacommondatabase forustousetocompareourdatawithNASA'smicrogravitydata
than0.1gramssothattheparticleshadlitt~e efect.onthefuel properties.
百letrajectoriesoftheseparticleswererecqrded)yahighsp即 d videocamerawhich'wasconectαitoavJdeqsystemandaTV monitorfortherealtimeobservationofbothflowfieldandspreading flame.
Inordertoconstructasingle2・D f).ow-vectordiagram.by combiningtheindependentlyobtainedgas-~hase PTLSandliquid- phasePTLS，asmoke-tracetechnique(STf)初出 apliedto'visualize theoveralstructureofflame-induc巴dairflo，wintheg儲 phaseand. liquidconvectionintheliquidphasesimultaneously. 百leglas containerenclosingtl1eflam~ spreadtrayw出 filedwithJapanese incensesmoke. 百letraywasfiledwithn-propanol;thefuelwas sededwiththesmalaluminumparticles~ use4fortheearlier P1LSmeasurements. Afterauniformsmokelayerwasformedover theliquidsurface，thefuelw出 igr泊ted.
DualWavelemrthHoloID'aDhicInterferometrv白 羽 喧 n ThebasicprinciplesbehindDWHIarethesameasthoseforthe
singleHI[lto，Masuda，andSaito，191;Ito，Saito，andCremers， 195;andTashtoush，Narumi，lto，Saito，andCremers，196]. A schematic of D W H I is shown in Fig. 2. D W H l is an indirect measurementtechniquewitharesponsetimeofIesthanamicro second and a spatial resolution of Ies s .than 土 0.1 m m in identifying ∞ncentrationdiference.百leDWHIh部 significantadvantagesover the microsampling technique，which has a spatial resolution of severalmilimetersruidaresponsetimethatisatbestontheorderof asecond. Inadition，themicrosampling techniqueisadirect techniquethatwilcausealargephysicaldisturbanceintheflowfield [Saito，Wiliams，andGordon，'1986].
and MiIler and Ros，.192] and our previous
[Ros， ~994; experimeI?-ts[Ito，Masuda，.andSaito，191;Ito，Saito，andCreniers， 195;andTashtoush，Narumi，Ito，Saito，apdCremers，196]. The fuelwasuniformlyignitedatoneendbyasmalpilotflame.High
mc=.oζコ 百lermcトcouples
Videorecordcr
Flgure1 Experlmentalapparatus01ParticleaTrackLasera Sheet(~TLS) system.
presure凶trogenw出 supliedfromanitrogencylindertoextinguish theflame.
VelocitvMeasurementwi血 aParticleTrackLaserShetSvstem {PTLS)andVisualizationofFlame-InducedAirF}(HV_wltha SmokeTraceTech凶 αue(S'IT)
Fromourpreviousstudies[Qian，.Ishida，andSaiω，194;and fIiranoandSaito，195]，welearnedthataPTLStechniquewitha highsp巴edvideocamera(2mslframewithashuUersp関 dofO.2ms) servesbestofourp岬 ose. Wit1lsignificantlyfewerparticles，the PTLSc叩 measureprofilesofbothstreamlinesand2-Dvelodty profilesnearlysimultaneously.Ahigh，spedcamerasystemwi白 血 ultravioletlensandanimageintensifierwereusedωobtainthe velocity?lfp紅 ticlesin500frames/ssp閃 d..Usinga4W Ar-ionlaser withabeamstabilizerandacylindricalens，almmthickshetof l a s e r l i g h t w i t h a n a p p r o x i m a t e l y 4 5 d e g r e e o p e 凶 n g 'a n g l e w 路 established(Fig;1)andguidedbyanopticalfibertotheplacewhere themeasurementnededtobedone.
V e l o c i t y p r o f i l e s o f t h e .l i q u i d a n d t h e g a s c o n v e c t i o n w e r e measuredindependent1yusingP1LS. Forthemeasurementofgas phaseconv巴ction，talcp~cles weredisperseduniformlyoverthe fuelsurface. Forthemeastirementofliquidconvection，aluminum particlesof15土( 5)μmdiameterweresprinkledonto:theliquid surface. Somealuminumparticlesfloatedontheliquidsurfaceand othersenteredintotheliquid.ThealuminumparticlesusedwereIes
l10niむ。r
143
Flgure2 A'schematlc01DWHIsystem.
Inthepresentstudyweuseda2・D modelofD羽引1and experimentalydeterminedthebestposible2-Dconditionforthe measuremen.t Be心 ausethebasicprinciplesofDWHlaredetailedin [SpatzandPoulikakos，192;andlto，Narumi，Saito，andCremers，