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LiquidConvectionUnderneaththeFue!SurfaceduetoEvaporation 23
fewthickhorizontalfringeswereconfirmedinFig.3(b).Adetailedscrutinyoftheinterferogramsfoundthatthe convectivemotionocurs1~1.5mm belowthefuelsurface.Awavyfringepaternat1.5secondsindicatesthe convectivemotjon.
A seriesofinterferogramsinthegasphaseisshowninFig.3(c).Onefringeshiftcorespondsto1.7vol~ら concentrationofmethanoIvaporwith160mmpathlength.Whentheshuterisopenedbytheair-cylinders，the interIerometricfringesappearoverthesurfaceandreachthequasi-steadystatewithinabout2seconds. Interferometricfringesaredistortedbytheinducedairflowbytheshuterunti10.2secondsfromtheonsetof evaporation，butaresuppressedwithin0.3seconds.Concentrationprofilescanbeobtainedfromthesepictures.
Fig.4(a)showsatypicalvideoimageofthefringesatquasi-steadystatecondition.They-cordinateindicates thenormaldistancefromtheliquidsurface.Thetransientconcentrationprofilealongthey-cordinateatthe centerofthetrayisalsoshowninFig.4(b).TheconcentrationattheInterfacebetweengasandliquid(CIGL)is determined.byextrapolatingtheconcentrationdistributioncurvestothefuelsurface.ThehistoriesoftheCrGLfor diferentsurfacetemperature areshowninFig.5(a).Thesolidsymbolsinthesefiguresshowtheconcentration fortheequi1ibrium vaporpres sure，whilehollowsymbols representthemeasureddata.Themeasurementofthe
0.0s 0.2s 0.3s 0.5s
1.0s 1.5s 2.0s
(a) (c)
Fig.3.Typicalpic如 resofthermography(a)，interferograminliquidphase(b) andinterferogramingasphase.(c).
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