燃烧算例ppt课件

FluentCombustionModelingCaseStudies1999UserGroupMeetingShortCourse GrahamGoldinFluentInc Threecasesstudies IFRFswirlingpulverizedcoalflameGELM 1600gasturbinecombustorLargeEddySimulationofLPCinstability Case1 IFRFswirlingpulverizedcoalflame IFRFindustrialscalefurnaceBuiltonsimulationbyPetersandWeber 1997 MathematicalModelingofa2 4MWSwirling PulverizedCoalFlame CombustionScienceandTechnology 122 131 Ref 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 model parametersfromRef 1 twostepreactionVOL 2 46O22 17CO 0 633CO2 2 118H2O 0 071N2CO 0 5O2CO2modelconstantsA 0 6 B 1020 standardA 4 B 0 5 Adjustedspecificheat s 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 opticalthickness 1 WSGGMforabsorptionco efficient Absorptionco efficient m 1 NOxmodeling ThermalandfuelNOx O frompartialequilibriumassumptionPost 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 http www me berkeley edu 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 eddiesandresolvethelargeturbulentstructuresinspaceandtimeThe isotropic smallscales 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 Axisymmetricmodel48kquadcellsingridgridsize 0 3mm Taylorlengthscale 0 9mmQUICKspatialdifferencing thirdorder SecondordertimedifferencingDt 10 5s inlet flameholder measurementlocati