熱能工程 授L‘EcoleCentralede中法工程師MechanicApplication–GasTurbineCombustion&Lecture2-CombustionFundamentalsAssoc.Prof.LIUYuying(SchoolofEnergyandPower熱能工程 授MechanicApplication–GasTurbine引 2學第1章航空燃氣渦輪發動機的基本工作原 10學的技術難點2學?航空燃氣渦輪4學?壓氣機部件2?渦輪部件的工作原2學第2章的結構強度與振 10學引1葉片強2學強2葉片振2學轉子振動與臨界轉2疲1學第3章燃燒與燃燒 10學燃燒與燃燒室1燃燒基礎知4學主燃燒41學熱能工程 授Part3:Combustionand燃燒與燃燒室概述（1學時燃燒基礎知識（4學時主燃燒室（4學時加力燃燒室（1學時熱能工程 授3.2CombustionFlameDropletevaporationandFlamespeedandFlame熱能工程 授3.2.4Flamespeed&Flammability火焰速度和可燃性邊DiffusionFlameandPremixedDiffusionFlame（擴散火焰Foradiffusionflame,thefuelandairare yuntiltheflameisPremixedFlame（預混火焰Forapremixedflame,thefuelandairareuniformlybeforeitisignitedtoformaareshort,blue,noisyandthereactionsarevirtuallycomplete.non-luminousflamearelong,yellow,quieterandthereactionsplete.luminous熱能工程 授Diffusionflame&PremixedDiffusionflamesaredominatedbythemixingofthereactants,whichcanbeeitherlaminarorturbulent,reactiontakesplaceattheinterfacebetweenthefuelandoxidizer,SootformationThereisnofundamentalflame擴散火熱能工程 授FlameFlamespeed(alsocalledLaminarBurningVelocityvelocity,orlaminarflamespeed層流火焰速度 isthevelocityatwhichflamemovethroughthecombustionwaveandtowardstheunburnedinthedirectionnormaltothewave求解方法：Two-PartsApproximation(分區近似法)solve需了解燃燒過熱能工程 授Flamespeed熱能工程 授FlamespeedSLwsin(/未燃氣體速度的垂直分whereφ/2hadbetterbetakenatthecentralportionoftheconedescribedbySchlierenedgeorinnershadowcone熱能工程 授LaminarBurningVelocityInfluentialFactorsThelaminarburningvelocitydependsfuelfuel-airmixtureinitialtemperatureofthepressureofthe熱能工程 授Effectsofφ,FuelTheumburningvelocitiesarefoundjusttobetherichsideofTypically,ahigherlaminarburningvelocityisassociatedwithahigherflame熱能工程 授Effectsofφ,Fuel熱能工程 授Effectsofφ,Fuel熱能工程 授Effectsofφ,Fuel戊丁熱能工程 授熱能工程 授EffectsofFuelair熱能工程 授Effectsofinitialtemperatureofthevarious提高可燃物初Theburningvelocityincreaseswiththetemperatureofthe熱能工程 授Effectsofpressureofthe甲烷，P增，SLtheflametemperaturebecausethereislessdissociation,andhencetheburningvelocityshouldbeButlessdissociationmeanslessactiveradicalsareavailabletodiffuseupstreamtoenhanceflamepropagationBotheffectsare熱能工程 授Effectsofpressureofthe熱能工程 授EffectsofpressureoftheMagnitude:

熱能工程 授Forstoichiometrichydrocarbonmixturesinambientair,theflameisapproxima ymovesatabout0.4m/s;forhydrocarbonmixtureitisabout3m/sMeasurementscarriedoutinlargevolumes,i.e.roomsratherthanpipes,showthattheratesatwhichflamesspreadinflammablemixturesisroughlycomparablewiththespeedoftraffic:Propane/air–slowwalkat3km/h(0.85m/s)步行Hydrogen/air–cyclingat16km/h(4.4m/s)自行車Hydrogen/oxygenfastcarat130km/h(36m/s）汽車熱能工程 授FlammabilityCombustiblegasesorvapoursarecapableofburninginairoroxygen,onlywithincloselydefinedlimitsofconcentration-flammablelimitsTheseflammablelimitsextendoneithersideofthestoichiometricmixturetothepointswhereit eseithertoorichortooweaktoignite.Therearemixtureratiosthatwillnotself-supporttheaftertheignitionsourceisTheleanestandrichestconcentrationsthatwilljustself-supportaflamearecalledtheleanandrichflammabilitylimits,respectively.Notethattheupper(rich)limit（富邊界）formanyfuelsaboutΦ=3andthelower(leanlimit（貧邊界）isabout熱能工程 授Flammabilitylimits熱能工程 授FlammabilitylimitsFrom:Glassman,combustion(4th熱能工程 授FlammabilitylimitsFrom:Keating,Appliedcombustion(2nd程 授熱能工程 授能工程 授能工程 授熱能工程 授熱能工程 授熱能工程 授Flammabilitylimits:Influential熱能工程 授Flammabilitylimits:InfluentialForsimplehydrocarbons(ethane,propane,…,pentane),therichlimitsextendalmostlinearlywithincreasingpressureatarateofabout0.13vol%/atmtheleanlimitappearstobeaffectedbythe lb/in2=1atm=14.2247熱能工程 授Flammabilitylimits:InfluentialTherangeofflammabilityinairisalwayssmallerthanthatinpureoxygen,althoughthelowerlimitisnearlythesameinoxygenasinair.LeanRich445522熱能工程 授Flammabilitylimits:Influential熱能工程 授Flammabilitylimits ysisofthedatasuggestthatforeachfuel,theweakandrichlimitcorrespondtothesameminimumflametemperature.SoformanyFormethanethisisabout1400K(comparedwith2200Kmax.stoichBelowthistemperaturethereactionsarenotsufficientlyfasttoleadtocontinuouscombustionandthemixtureisdeemednottobe熱能工程 授3.2.3MechanismofLiftedConsideringalongenoughBunsenburnerfiringwithincreasingflowrateWhenthecoldpremixedgasesflowinadirectionoppositetothewavepropagationandtravelatavelocityequaltotheflamespeed,thewave esstationarywithrespecttotheburner熱能工程 授BunsenWhentheflameislocatedintheburnertube,therequirementforflameholdingis:SL=u1Whentheflameisaconicalinshape,therequirementforflameholdingis:SL=u1sin(α/2)whereαistheconeangleNotethelocalflatshapeofth