現(xiàn)代燃燒及數(shù)值模擬

現(xiàn)代燃燒技術(shù)及數(shù)值模擬

大作業(yè)改變空氣的進(jìn)氣速度，從0?5m/s到1m/s.ProblemDescription:ThecylindricalcombustorconsideredinthistutorialisshowninFigure11.1.Theflameconsideredisaturbulentdiffusionflame.Asmallnozzleinthecenterofthecombustorintroducesmethaneat80m/s.Ambientair（周圍氣體）entersthecombustorcoaxially（同軸地）at1m/s.Theoverallequivalenceratioisapproximately0.76（about28%excessair）.Thehigh-speedmethanejetinitiallyexpandswithlittleinterferencefromtheouterwall,andentrainsandmixeswiththelow-speedair.TheReynoldsnumberbasedonthemethanejetdiameterisapproximately5.7*10e3.Figure11.1:CombustionofMethaneGas（甲烷氣體）inaTurbulentDiffusionFlameFurnace反應(yīng)方程：CH4+2O2一CO2+2H2O網(wǎng)格:

Startthecalculationbyrequesting500iterations-1e+u1--1e+u1-1e-01k-021e-U：31--U41e-U51e-U&IterationsSc^kd足sidgl#Apr14,2UU?ELUETfT6.2(2dlf?gr^gvt?dlspt,Sc^kd足sidgl#Apr14,2UU?ELUETfT6.2(2dlf?gr^gvt?dlspt,sit)FLUENT[0]FluentInc2.57c+032.46e+032.34t+03a.13c+032.00-1+031.89t+031.66t+03144t+031.21t+031.09t+039.8k+031.78t+031.55t+O31.33C+038.68c+0a7.54t+026.4U+025.a7c+O24.14t*02CorrtourjoEStaticTtmptrrturt[kJApr14.3007FLUENT6.S(2d,stgrtgrttd,spt,slct)3.oot+oaSolutionUsingNon-ConstantHeatCapacityPostprocessing（后處理）

PlotcontoursofspecificheatDisplayvelocityvectors

PlotcontoursofstreamfunctionPlotcontoursofmassfractionforeachspeciesThemassfractioncontourch4or

ThemassfractioncontoursforO2

ThemassfractioncontoursforCO2ThemassfractioncontoursforH2OMass-WeightedAverage

StaticTemperaturepressure-outlet-91073.6141pressure-outlet-91073.6141(m/s)pressure-outlet-911.5759Mass-WeightedAverageVelocityMagnitude(m/s)pressure-outlet-911.5759NOxPrediction(NO*預(yù)測(cè))xReviewthesolutionbydisplayingcontoursofNOmassfractionCalculatetheaverageexitNOmassfraction.Mass-WeightedAverageMassfractionofNO()pressure-outlet-91.6889176e-05DisablethepromptNOxmechanismandsolveforthermalNOxonly.ContoursofNOMassFraction:ThermalNOxFormationMass-WeightedAverageMassfractionofNO()---------------------------------------------------pressure-outlet-91?135168e-05ContoursofNOMassFraction:PromptNOxFormation

ContoursofNOppm:PromptNOxFormationMass-WeightedAverageMassfractionofMass-WeightedAverageMassfractionofNO（）pressure-outlet-95.6624255e-061、數(shù)據(jù)原理的數(shù)據(jù)：（1）進(jìn)氣速度為0.5m/s（2）Themass-weightedaverageexittemperatureisabout1775K（3）Thearea-averagedexitvelocityisabout3.10m/s.（4）Themass-weightedaverageexitNOmassfractionisabout0.00309.（5）Themass-weightedaverageexitNOmassfraction,withthermalbutnopromptNOxformation,isabout0.00305.（6）Themass-weightedaverageexitNOmassfraction,withonlypromptNOxformation,isabout0.000044.（7）Thecombustionmodelingresultsaresummarizedinthefollowingtable:PeakTemp.（K）ExitTuiiij）.（K）ExitV^loi.ityWs）Constant%2935215ii3.75Variable%223117753.10改變參數(shù)后的實(shí)驗(yàn)結(jié)果：（1）Mass-WeightedAverageStaticTemperature（k）pressure-outlet-91073.6141（2）Mass-WeightedAverageVelocityMagnitude（m/s）pressure-outlet-911.5759（3）Mass-WeightedAverageMassfractionofNOpressure-outlet-91.6889176e-05（4）Mass-WeightedAverageMassfractionofNO,withthermalbutnopromptNOxformation:pressure-outlet-91.135168e-05（5）Mass-WeightedAverageMassfractionofNO,withonlypromptNOxformation:pressure-outlet-95.6624255e-06（6）進(jìn)氣速度為1.0m/s2、實(shí)驗(yàn)分析：由實(shí)驗(yàn)數(shù)據(jù)可以看出：（1）當(dāng)進(jìn)氣速度變化時(shí)，出口氣流的溫度、速度以及污染物排放量將發(fā)生變化。（2）當(dāng)進(jìn)氣速度增大時(shí)，出口氣流溫度降低。分析原因：進(jìn)氣速度增大，而進(jìn)氣截面不發(fā)生變化時(shí)，則冷卻作用增強(qiáng)，消耗了燃燒生成的能量增多，這樣燃燒后的混氣溫度降低。（3）當(dāng)進(jìn)氣速度增大時(shí)，出口的氣流速度增大。這是因?yàn)檫M(jìn)口氣流速度增大且吸收了更大的熱量，出口動(dòng)能增大，速度增大。（4）當(dāng)進(jìn)氣速度增大時(shí)，NOx、含熱力NOx、只含順發(fā)NOx的量都分別有所下降。原