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Transientinfraredtemperaturemeasurements01 liquid-fuelsurfaces: results01studies01flames spreadoverliquids
TadashiKonishi，AkihikoIto，andKozoSaito
Anin企aI吋 thermographtechniquewithan8-12・μmspectralrangewasusedtomeasuretransient two-dimensionalprofilesofliquid(l-propanol)surfacetemperatures. AnIRcamerawasplacedoverthe liquid，alowingustoobservethefuelsurfacethroughpropanolvapor. Tousethistechnique，onemust know the emis sivi句 T of the liquid surface and the IR absorption of both the liquid propanol and the propanolvapor. Theemisivityoftheliquidpropanolwasdeterminedwithafinethermocoupletem開 peraturemeasurement，IRabsorptionwiththepropanolvaporwascalibratedwithablackbodysource， andIRabsorptionwithaliquidpropanolwastheoreticalyestimated. Theacuracyofour主企訂ed thermographtechniqueprovedtobebeterthan97%indetectingtheliquid-surfacetemperaturewitha temperaturesensitivityof0.1oC田 ldatimeresponseof30ms.@2000OpticalSocietyofAmerica
OC18codes:・ 10.3080，120.6780，120.1740.
1. Introduction
Developmentofaremote-sensingsystemthatcanbe usedforacuratedetectionofsmalamountsoftem- peraturechangeinarelativelylargeliquid-fuelsur- face町 eaisofcurentinterest，becauseofproblems withfiresandexplosionsofstoredflammableliquids. Thermocouplesarewidelyusedtodetectchangesin liquidtemperature，however，theyhavelimitations. (1)Useofthethermocoupleisapoint-by-pointmea- surementtechniqueandisnotthebestavailable means for monitoring transient two-dimensional (2四 D)profilesofliquid戸 surfacetemperatures.1 (2)It isoftendificulttQpinpointthelocationofthether- mocouplebeadpreciselyonthefuelsurface，p訂 ticu- larlywhenthefuelsurfaceislargeorwhenthelevel ofthefuelsurfaceischanging. Asuddenpresure change in the storage tank could cause sloshing，
T.Konishi(konishi@oita-ct.ac.jp)iswiththeDepartmentofMe- ch町 ucalEnginering，OitaNationalColegeofTechnology，1666
whichwouldgenerateasurfacewave，makingitdif- 五culttomeasurethethermocoupletemperature.
Toovercomethelimitationsrelatedtothethermo- couple，weapliedanIRthermographtechniquewith ahightemperatureresolutionandafastresponse time. AnIRcamerawasplacedovertheliquid-fuel surface，makingobservationposiblethroughtheliq- uidvaporthathadaccumulatedovertheliquidsur- face. TheIRcamerawasusedtomeasuretransient 2-Dtemperatureprofilesofaliquid-fuelsurfacetem- perature，anadvantagenotposiblewiththermocou- plemeasurements. However，boththeliquid-fuel surfaceandthefuelvaporcouldabsorbIRradiation. Therefore，theseefectsneedtobeestimatedcorectly toobtainanacuratetemperaturebyuseoftheIR technique.
PreviouslyweapliedanIRcameratomeasurethe temperatureofasolid-fuelsurfaceduringcombus回 tion.2，3 Inthatstudy，anIRcamerawasplacedover theburningsolidfueltoprovideobservationthrough the宜ame. Ourchalengewastomeasure2-Dpro四
回
and the combustion-gas temperatures (1000- 15000C). Weovercamethisproblembysatisfying theconditionofanopticalythin宜ame(emisivity <1)andbyusinganarrowbandpassfilterthatcan eliminateIR.absorptionwithCO2 andH20.2 Inas-
0152，Japan. A.ItoiswiththeDepartmentof InteligentMachine，andSystemEnginering，HirosakiUniversity， 3Bunkyo-cho，HIros品ci，Aomori036・8561，Japan. K.8aitois withtheDepartmentofMechanicalEnginering，Universityof Kentucky，514B CRMSBuilding，Lexington，Kentucky40506- 0108.
Received27July19;revisedmanuscriptreceived2March 20.
0003・6935/00/244278・06$15.0/0 @ 2000OpticalSocietyofA merica
4278 APPLlEDOPTICS/Vo.l39，No.24/20August2000
Maki，Oita870
surfacetemperature$byelim- inatinginterferenceofthe丑ame. Thiswasnotan easytaskbecausethetypicalpyrolysisofasolid-fuel surface(350OC)ismuchlowerthanthesot-particle
・
五lesoftransientsolid