燃烧学经典算例PPT演示课件

FluentCombustionModelingCaseStudies1999UserGroupMeetingShortCourse,GrahamGoldinFluentInc.Threecasesstudies:IFRFswirlingpulverizedcoalflameGELM-1600gasturbinecombustorLargeEddySimulationofLPCinstability,Case1:IFRFswirlingpulverizedcoalflame,IFRFindustrialscalefurnaceBuiltonsimulationbyPetersandWeber(1997),MathematicalModelingofa2.4MWSwirling,PulverizedCoalFlame,CombustionScienceandTechnology,122,131Ref.1,exhaust,7coolingloops,measurementlocations:z=0.25m,0.85m,combustionair:swirlno.=0.923,flowrate=2684kg/h,coalflowrate=263kg/h,withtransportairflowrate=421kg/h,1/4geometry,Grid,3D,onequartergeometrymodelduetoperiodicityUnstructuredhexahedralmesh70kcellsbeforeadaption260kcellsafterregionadaptionnearinletMaximumequi-angleskewof0.53,Turbulencemodeling,Standardk-eturbulencemodel,standardwallfunctionsnotsubstantiallysensitivetotheturbulencemodel,Meanvelocitymagnitude(m/s),Gasphasecombustionmodeling(1),EddyDissipation(Magnussen)modelparametersfromRef.1twostepreactionVOL+2.46O22.17CO+0.633CO2+2.118H2O+0.071N2CO+0.5O2CO2modelconstantsA=0.6,B=1020(standardA=4,B=0.5)Adjustedspecificheats(SIunits),Speciesc0c1c2c3c4c5c6N21.027e32.162e-21.486e-4-4.484e-8CH42.005e3-6.814e-17.086e-3-4.714e-68.513e-10CO1.047e3-1.568e-15.399e-4-3.011e-75.050e-11H21.415e41.737e-16.900e-4CO25.354e21.279-5.468e-4-2.382e-71.892e-10H2O1.938e3-1.1813.644e-3-2.863e-67.596e-10O28.763e21.228e-15.583e-4-1.202e-61.147e-9-5.124e-138.566e-17,Gasphasecombustionmodeling(2),Meantemperature(K),Gasphasecombustionmodeling(3),MeanCOppm,dry,Discretephasemodeling(1),GottelbornhvBbcoalproximate(weight%,dry),volatiles55.0,fixedcarbon36.7,ash8.3ultimate(weight%,daf)C80.36,H5.08,N1.45,S0.94,O12.17LowerCalorificValue(LCV,MJ/kgdaf)volatiles32.3,char32.9Rosin-Rammlersizedistributionsmallest1mm,largest300mm,mean45mm,spread1.36Singleratedevolatizationmodel,A=2*105s-1,E=7.4*107J/kmolKinetics/diffusion-limitedsurface(char)combustionO2diffusionrateconst=5*10-12kg/m2sPa,A=6.7kg/m2sPa0.5,E=1.14*108J/kmolDiscreteRandomWalk(DRW)model21600tracksperDPMiteration,10particlesizes25gasphaseiterationsperDPMiteration,Discretephasemodeling(2),Tracksof1mmparticles,coloredbyparticletemperature(K),Radiationmodeling,P-1radiationmodel(opticalthickness1)WSGGMforabsorptionco-efficient,Absorptionco-efficient(m-1),NOxmodeling,ThermalandfuelNOxOfrompartialequilibriumassumptionPost-processed:assumedshapebpdf,MeanNOppm,dry,Results(1)Velocityfield,Meanswirlvelocity(m/s),Meanaxialvelocity(m/s),Results(2)Turbulencefield,Turbulenceintensity(m/s),Results(3)Temperature/speciesfield,Meantemperature(K),MeanO2(volume%,dry),Results(4)Speciesfield,MeanCO2(volume%,dry),MeanCO(ppm,dry),Results(5)Velocityfield,MeanNO(ppm,dry),Solutionstrategy,13equationssolved:1pressure,3momentum,1energy,2turbulence,1radiation,5gasphasespecies,(2pollutantspost-processed)Segregated,pressurebasedsolverSolutionprocedure:a.coarsegrid,coldflowsolutionb.gasphasecombustionc.particlesd.radiatione.adaptionSecondorderupwinddiscretization,Case2:GELM-1600gasturbinecombustor,courtesyofNovaResearchandTechnologyCorp.,Calgary,Canadanon-premixed,naturalgas12.8MW,19:1pressureratio(fullload)annularcombustionchamber,18nozzles,swirlvanes,fuelinletnozzles,dilutionairinlets,Grid,3D,1/18thgeometrymodelduetoperiodicityMulti-blockhexahedralmeshMaximumequi-angleskewof0.84286kcells,Turbulencemodeling,Standardk-eturbulencemodel,Pathribbonscoloredbytemperature(K),Gasphasecombustionmodeling(1),LaminarFlameletmodel22species,104reactionsreducedGRI-MECH1.22mechanismA.KazakovandM.Frenklach,/drmFlameletssolvedinmixturefractionspaceDifferentialdiffusion(Leeffects)included,MeanmassfractionofOH,Gasphasecombustionmodeling(2),DeviationfromchemicalequilibriummeasuredbyDamkohlerno.aqisthelaminarflameletextinctionstrainrate=11700s-1,Damkohlernumber,Gasphasecombustionmodeling(3),Meantemperature(K),Gasphasecombustionmodeling(4),Clippedcontoursofand,NOxmodeling(1),ThermalandpromptNOx:ZeldovichthermalNOdominant:SpeciesandtemperaturefromLaminarFlameletmodelPost-processed:assumedshapebpdf,MeanNOppm,wet,NOxmodeling(2),LaminarFlameletmodel,Equilibriumfmodel,NOxmodeling(3),PlotofNObustorload,Case3:LargeEddySimulationofCombustionInstability,Combustioninstabilityoccurswhenpressurefluctuationsareinphasewithheatreleasefluctuations(Rayleighcriteria)Commoninleanpremixed(lowNOx)systemsUnsteadysolution-LES!RuhrgasSinoxIburnerexperimentsBuchner,H.andLeuckel,W.(1995),FinalreportoftheGERGPC5,AcousticsandBurnerNoise,Instantaneousvelocityvectorscoloredbyvelocitymagnitude(m/s),LargeEddySimulation(1),DirectsolutionofreactingNavier-Stokes,wherealllengthandtimescalesareresolved,iscomputationallyintractableLargeEddySimulation(LES)spatiallyaverage(filter)thesmall(sub-grid)eddiesandresolvethelargeturbulentstructuresinspaceandtimeTheisotropicsmallscales,whichdissipateenergyfromthelargescales,aremodeledasaneddyviscosityLESismoreexpensivethanRANSduetospatialresolutionrequirementsandtheunsteadysolutionLESistheappropriatetoolforhighlyunsteadyflowswithdominantturbulentstructures(e.g.certainexplosions),Underlyingtheory,LargeEddySimulation(2),Favre(densityweighted)filteringofageneralvariable,jBoxfilter,whereDisthegridwidth,Filteredcontinuityequation,Governingequations,LargeEddySimulation(3),Filteredmomentumequationsubgridstresstensormodeledas(Smagorinsky)SmagorinskyconstantCs=0.1,Governingequations,LargeEddySimulation(4),FilteredspeciesGequationforpremixedcombustionTurbulentflamespeeddeterminedbytheRNGmodelLaminarflamespeedSl=23cm/sSourcetermintheenergyequation,Governingequations,SolutionParameters,Axisymmetricmodel48kquadcellsingridgridsize0.3mm,Taylorlengthscale0.9mmQUICKspatialdifferencing(thirdorder)SecondordertimedifferencingDt=10