Page 111 - konishipaper
P. 111
A.Ito DepartmentofProduclionSystemEnginering，
OitaUniversity， Oita870司 1，Japan
A.Narumi DepartmentofMechanicalEnginering，
KanagawaInstituteofTechnology， 1030Shimo-Ogino，Atsugi， Kanagawa243-02，Japan
T.Konishi DepartmentofMechanicalEnginering， OitaNationalColegeofTechnology，
16MaikiOita870-01，Japan G.Tashtoush
K.Saito1 Mem.ASME
C.J.Cremers FelowASME
DepartmentofMechanicalEnginering， UniversityofKentucky， 521CRMSBuilding，
Lexington，KY40506
Introduction
τbephenomenonoffiamespreadoverliquidsisofcurent interestbecauseofitsimportancetofiresafe，匂 and出ecuriosityof combustionresearchersaboutthefundamentalmechanismof出e fiamespread.Ros(194)叩 d凹 rano佃 dSuzuki(193)published 叩 excelentreviewoftheliteratureon也isproblem.Wiliams (1985)providedthetheoreticalbackgroundoftheproblem.Al thosestudiesdiscusedmanyoftheproblems白atnedtobe investigated.
τhepresentpaperisacontinuationofourpreviousstudieson Eむ nespreadoverliquids(Ito，Masuda，Saito，191;Ito，Saito，姐d
TheMeasurementofTransient
TwoDimensionalProfilesof VelocityandFuelConcentration
OverLiquids
Werecent1ydevelopedtwodiferentopticaltechn!quesinordertosimu1taneouslymea- suretransienttwo-dimensionalpro.戸lesofvelocity，tempera印 re，andかelconcentration thatweregeneratedbyaspreadingfiameoverliquidかe1s.Onetechniqueemp10ysa αD rticle-track system combined with a laser-she et system (LSPT) and a high-spe ed
camerα，whiletheothertechniqueemp10ysdualwαvelengthholographicintel作rometry
，
(DWHI).刀zeLSPTsystemrevealedtransienttwodimensionalpr・ofilesofiame-induced fiow，whileDWHIrevea1edt;wo-dim!fnsionalprofilesofue1concentrationoverliquids.In thispaperwepresentaseriesofvelocityprofilesfora.pulsatingfiamespreadover l-propanolandconcentrationprofilesforgaseousl-propanoldeterminedwithLSPTand
DWHI，respectively.
圃
oversolids，whichhavenocondensedthaseconvection(Wiliams， Cremers，195;andTashtoush，Narurni，1to，Saito，andCremers， 1985).Thus，itisimportanttoacuratelymeasuretempera回 目 印d
196):Inthesestudiesweapliedholographicinterferometry仔宜) toobtainadetailedandinstantaneoustemperaturedis凶 butionin theliquidphasenearthefuelsurface.1neachofmethanol，ethanol， and.1-propanolwefoundsubsurface-liquidconvectioninboththe qniformspreadandpulsatingspreadregions.Tounderstandthe mechanismsoffiamespread泊 bo血 regions，researchers凶 edto identi，巧 theheat仕ansferprocesocuringbetwentheflame's leadingedgeandtheliquid，whetheritocursthroughthegas phase，liquidphase，orboth.Whentheliquidconvectionispro- ducedandittravelsぱleadof也efiame'sleadingedge，出efi回 le spreadislikelytobec.ontroledbyitbecausetheconvection cariesthehigh-temperatureliquidaheadof血e丑ame'sleading edge.官邸 enh叩cesevaporationofliquidvaporresultingin出e
ITowhomcorespondenceshouldbeadresed.e-m且iJ:saito@engr.は y.edu. Con住ibutedby血eHeatTransferDivisionforpublicationin白eJou即 AL OF HEATTRANSFERandpresentedat'97町 ECE.Manuscriptreceivedby出eHeat
sfer Division，Feb.25，19 98; revision r
巴
velocityprofilesintheliquidphase.Aldta(1972)wasthefirst researchertoaplyashadowgraphtechniquetovisualizetheliquid convection.Hereportedtheformationofliquidconvection出血e pulsatingregion，butnoliquidconvectionintheuniformspread region.BasedonAkita'sdata，GlasmanandDryer(1981)pro- posed出attheuniformspreadiscon位oledbyheatconduction throughthegasphase，whilein血epulsatingregiontheliquid convectionp'laysan凶 portantrole.
Tosolve出isproblem，wedevelopedanHIsystemtomeasure 血e住ansienttemperatureof出eliquid(Ito，Masuda，andSaito， 191).TheresponsetimeofourHIsystemwasles白 血 l microsecond.Weestimatetheuncertaintyofthespatialresolution tobe0.1mm，andthetemteratureres01utiontobe:tO.loc(Ito， M出 uda，andSaito，191).UsingtheHIsystem，weobserveda largeliquidconvectionbot.intheuniformandpulsatingspread regions.官leliquidconvectionintheuniformspreadregionwasa surprisebecausetheheadoftheliquidconvectionpreceded出e fiame's leading edge by ap pro泊 mately 1 c m (Ito， Masuda， 組 d Saito，191)，whichwasentirelydiferent企omAldta'sresult
Tr
c e i v e d ， O c t. 1 5 ， 1 9 9 8 . K e y w o r d s : ntTechniques.AsociateTechnical
四 Fire，Flame，HeatTransfer，Laser，Measurem
巴
Editor:M.Kaviany.
JournalofHeatTransfer Copyright@ 1999byASME MAY1999，Vo.l121I413
formationofa宜ammablernix印 reoffuelandairthroughwhichthe E む n e c 佃 s p r e a d . I f t h e r e is n o l i q u i d c o n v e c 丘 o n a h e a d o f 出 e fiame'sleadingedge，也emajorheat凶 lsfercanocurbetwenthe fia.me'sleadingedgeandtheliquidbyconductionandbyradiation inthegasphasebecauseconductionthroughtheliquidisnegligi- ble(GlasmanandDryer，1981).
However，theproposedmechanismfortheuniformspreadis
qu~s吐onable， becausethegas-phaseconduction.maynot仕 組sfer
suficientheatforthefiametospreadatarateofnearly10crnJs.
Liquidconvectionis.uniquetofi創 出 spreadoverliquidsandit
complicatesthespreadingprocesincomparisontofiamespread
