教程分析成果

热能工程 授L‘EcoleCentralede中法工程师MechanicApplication–GasTurbineCombustion&Lecture2-CombustionFundamentalsAssoc.Prof.LIUYuying(SchoolofEnergyandPower热能工程 授MechanicApplication–GasTurbine引 2学第1章航空燃气涡轮发动机的基本工作原 10学的技术难点2学•航空燃气涡轮4学•压气机部件2•涡轮部件的工作原2学第2章的结构强度与振 10学引1叶片强2学强2叶片振2学转子振动与临界转2疲1学第3章燃烧与燃烧 10学燃烧与燃烧室1燃烧基础知4学主燃烧41学热能工程 授Part3:Combustionand燃烧与燃烧室概述（1学时燃烧基础知识（4学时主燃烧室（4学时加力燃烧室（1学时热能工程 授3.2CombustionFlameDropletevaporationandFlamespeedandFlame热能工程 授3.2.4Flamespeed&Flammability火焰速度和可燃性边DiffusionFlameandPremixedDiffusionFlame（扩散火焰Foradiffusionflame,thefuelandairare yuntiltheflameisPremixedFlame（预混火焰Forapremixedflame,thefuelandairareuniformlybeforeitisignitedtoformaareshort,blue,noisyandthereactionsarevirtuallycomplete.non-luminousflamearelong,yellow,quieterandthereactionsplete.luminous热能工程 授Diffusionflame&PremixedDiffusionflamesaredominatedbythemixingofthereactants,whichcanbeeitherlaminarorturbulent,reactiontakesplaceattheinterfacebetweenthefuelandoxidizer,SootformationThereisnofundamentalflame扩散火热能工程 授FlameFlamespeed(alsocalledLaminarBurningVelocityvelocity,orlaminarflamespeed层流火焰速度 isthevelocityatwhichflamemovethroughthecombustionwaveandtowardstheunburnedinthedirectionnormaltothewave求解方法：Two-PartsApproximation(分区近似法)solve需了解燃烧过热能工程 授Flamespeed热能工程 授FlamespeedSLwsin(/未燃气体速度的垂直分whereφ/2hadbetterbetakenatthecentralportionoftheconedescribedbySchlierenedgeorinnershadowcone热能工程 授LaminarBurningVelocityInfluentialFactorsThelaminarburningvelocitydependsfuelfuel-airmixtureinitialtemperatureofthepressureofthe热能工程 授Effectsofφ,FuelTheumburningvelocitiesarefoundjusttobetherichsideofTypically,ahigherlaminarburningvelocityisassociatedwithahigherflame热能工程 授Effectsofφ,Fuel热能工程 授Effectsofφ,Fuel热能工程 授Effectsofφ,Fuel戊丁热能工程 授热能工程 授EffectsofFuelair热能工程 授Effectsofinitialtemperatureofthevarious提高可燃物初Theburningvelocityincreaseswiththetemperatureofthe热能工程 授Effectsofpressureofthe甲烷，P增，SLtheflametemperaturebecausethereislessdissociation,andhencetheburningvelocityshouldbeButlessdissociationmeanslessactiveradicalsareavailabletodiffuseupstreamtoenhanceflamepropagationBotheffectsare热能工程 授Effectsofpressureofthe热能工程 授EffectsofpressureoftheMagnitude:

热能工程 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)自行车Hydrogen/oxygenfastcarat130km/h(36m/s）汽车热能工程 授FlammabilityCombustiblegasesorvapoursarecapableofburninginairoroxygen,onlywithincloselydefinedlimitsofconcentration-flammablelimitsTheseflammablelimitsextendoneithersideofthestoichiometricmixturetothepointswhereit eseithertoorichortooweaktoignite.Therearemixtureratiosthatwillnotself-supporttheaftertheignitionsourceisTheleanestandrichestconcentrationsthatwilljustself-supportaflamearecalledtheleanandrichflammabilitylimits,respectively.Notethattheupper(rich)limit（富边界）formanyfuelsaboutΦ=3andthelower(leanlimit（贫边界）isabout热能工程 授Flammabilitylimits热能工程 授FlammabilitylimitsFrom:Glassman,combustion(4th热能工程 授FlammabilitylimitsFrom:Keating,Appliedcombustion(2nd程 授热能工程 授能工程 授能工程 授热能工程 授热能工程 授热能工程 授Flammabilitylimits:Influential热能工程 授Flammabilitylimits:InfluentialForsimplehydrocarbons(ethane,propane,…,pentane),therichlimitsextendalmostlinearlywithincreasingpressureatarateofabout0.13vol%/atmtheleanlimitappearstobeaffectedbythe lb/in2=1atm=14.2247热能工程 授Flammabilitylimits:InfluentialTherangeofflammabilityinairisalwayssmallerthanthatinpureoxygen,althoughthelowerlimitisnearlythesameinoxygenasinair.LeanRich445522热能工程 授Flammabilitylimits:Influential热能工程 授Flammabilitylimits ysisofthedatasuggestthatforeachfuel,theweakandrichlimitcorrespondtothesameminimumflametemperature.SoformanyFormethanethisisabout1400K(comparedwith2200Kmax.stoichBelowthistemperaturethereactionsarenotsufficientlyfasttoleadtocontinuouscombustionandthemixtureisdeemednottobe热能工程 授3.2.3MechanismofLiftedConsideringalongenoughBunsenburnerfiringwithincreasingflowrateWhenthecoldpremixedgasesflowinadirectionoppositetothewavepropagationandtravelatavelocityequaltotheflamespeed,thewave esstationarywithrespecttotheburner热能工程 授BunsenWhentheflameislocatedintheburnertube,therequirementforflameholdingis:SL=u1Whentheflameisaconicalinshape,therequirementforflameholdingis:SL=u1sin(α/2)whereαistheconeangleNotethelocalflatshapeofth