Where can I find properties for modelling the combustion of JetA liquid sprays? Where can I get good reaction kinetics for fuels such as kerosene, JetA etc ...
Most of these types of fuels are variable mixtures of heavier hydrocarbons and getting good property information can be difficult. The reaction mechanisms for JetA/air and diesel fuels contain hundreds of steps. A common modelling approach for these fuels is to start with an EDM ("mixed is burned") scheme and assume FUEL + O2 --> CO2 + H2O or FUEL + O2 --> CO + H2O. If you are setting up a JetA oil combustion simulation with EDM, use the properties and reactions in the template below rather than the oil_combustion.ccl template that comes with the CFX10 installation. There were several errors in the liquid properties in the oil_combustion.ccl template that require manual correction. The reaction kinetics in this template are for C10H22 (one of the major constituents of JetA fuel) and have been scaled to accomodate the difference in molecular weights. Note that the liquid Cp in the new template is specified using NASA coefficients. This option for liquids is not recognized by CFX-Pre, but will run fine in the solver. If you don't edit the liquid properties you should be able to write a .def file and run the solver despite the error messages in CFX-Pre. Another (better) option is to use the flamelet library generator that comes with CFX to generate a JetA library for your case. This produces a pretabulated solution for the flame chemistry based on the local fuel/air mixture. Flamelet libraries are better at predicting CO and other intermediates because many more reactions can be included chemistry. The flamelet generator is capable of generating flamelet libraries for kerosene (C7H16), which is similar to diesel and C10H22/C9H12 (components of JetA fuel). Flamelet libaries are the superior modelling tool when it comes to modelling the combustion of long-chain hydrcarbons. The flamelet approach reduces the number of equations that have to be solved while providing information about most of the significant intermediates. The information about concentrations of intermediate species such as O, CH and HCO can also be used to drive NOx models and improve NOx predictions. #======================================================================= # @(#) $Id: JetA.ccl,v 1.4 2005/03/08 15:54:57 cfdhf Exp $ #----------------------------------------------------------------------- # LIBRARY: # ######################################################################## # JET ENGINE FUEL MATERIALS LIBRARY FOR CFX-5 ######################################################################## # # This file includes the CCL description of material properties # supplied as part of the CFX-5 installation for running jet engine # calculations. # # Jet A is a mixture of several ingredients and actual properties # *do* vary: # # Molar Mass = 167.3137 [kg/kmol] .. 167.31462 [kg/kmol] # Density(L) = 775 [kg/m^3] .. 840 [kg/m^3] # # Ref. Enth. HF298(L) = -303.50 [kJ/mol] .. -265.09 [kJ/mol] # Ref. Enth. HF298(G) = -211.47 [kJ/mol] # (heat of vaporisation 320 [kJ/kg] .. 550 [kJ/kg]) # # Kin Visc(L)@T=38[C] = 1.4E-6 [m^2/s] .. 2.2E-6 [m^2/s] # ( .lt. 8.E-6 [m^2/s] @ T=-20 [C]) # # Values below have been defined according to: # - Heat of vaporisation LH = 320 [kJ/kg] # - Estimates for viscosity(G&L) and thermal conductivity(G) # ######################################################################## # MATERIAL: JetA Material Description = Vapour Jet A Fuel (C12H23) Option = Pure Substance Thermodynamic State = Gas Material Group = Gas Phase Combustion PROPERTIES: Option = General Material EQUATION OF STATE: Option = Ideal Gas Molar Mass = 167.31462 [kg kmol^-1] END DYNAMIC VISCOSITY: Option = Value Dynamic Viscosity = 5.E-06 [kg m^-1 s^-1] # Estimated value END THERMAL CONDUCTIVITY: Option = Value Thermal Conductivity = 1.E-02 [W m^-1 K^-1] # Estimated value END SPECIFIC HEAT CAPACITY: Option = NASA Format Reference Pressure = 1 [atm] Reference Temperature = 25 [C] TEMPERATURE LIMITS: Lower Temperature = 273.15 [K] Midpoint Temperature = 1000 [K] Upper Temperature = 5000 [K] END LOWER INTERVAL COEFFICIENTS: NASA a1 = 2.08692170E+00 [] NASA a2 = 1.33149650E-01 [K^-1] NASA a3 = -8.11574520E-05 [K^-2] NASA a4 = 2.94092860E-08 [K^-3] NASA a5 = -6.51952130E-12 [K^-4] NASA a6 = -3.59128140E+04 [K] NASA a7 = 2.73552890E+01 [] END UPPER INTERVAL COEFFICIENTS: NASA a1 = 2.48802010E+01 [] NASA a2 = 7.82500480E-02 [K^-1] NASA a3 = -3.15509730E-05 [K^-2] NASA a4 = 5.78789000E-09[K^-3] NASA a5 = -3.98279680E-13 [K^-4] NASA a6 = -4.31106840E+04 [K] NASA a7 = -9.36552550E+01 [] END END ABSORPTION COEFFICIENT: Option = Value Absorption Coefficient = 1.0 [m^-1] END REFRACTIVE INDEX: Option = Value Refractive Index = 1.0 [m m^-1] ENDSCATTERING COEFFICIENT: Option = Value Scattering Coefficient = 0.0 [m^-1] END END END # MATERIAL: JetA Liquid Material Description = Liquid Jet A Fuel (C12H23) Option = Pure Substance Thermodynamic State = Liquid Material Group = Gas Phase Combustion, Constant Property Liquids PROPERTIES: Option = General Material EQUATION OF STATE: Option = Value Density = 780 [kg m^-3] Molar Mass = 167.31462 [kg kmol^-1] END DYNAMIC VISCOSITY: Option = Value Dynamic Viscosity = 1.5E-03 [kg m^-1 s^-1] END tA Oxidation, WD2 CO Oxidation Additional Materials List = JetA, O2, CO, CO2, H2O, N2 END # REACTION: JetA Air WGS Option = Multi Step Reaction Description = JetA Air with Water/Gas Shift Reactions List = WD3 JetA Oxidation, WD2 CO Oxidation, Hydrogen Oxygen, Water Gas Shift Additional Materials List = JetA, O2, CO, CO2, H2, H2O, N2 END # # With NO formation # REACTION: JetA Air WD1 NO PDF Option = Multi Step Reaction Description = JetA Air Single Step and NO Formation with Temperature PDF Reactions List = JetA Oxygen WD1, NO Formation JetA PDF END # REACTION: JetA Air WD2 NO PDF Option = Multi Step Reaction Description = JetA Air Two Step and NO Formation with Temperature PDF Reactions List = WD2 JetA Oxidation, WD2 CO Oxidation, NO Formation JetA PDF END # REACTION: JetA Air WGS NO PDF Option = Multi Step Reaction Description = JetA Air with Water/Gas Shift and NO Formation with Temperature PDF Reactions List = WD3 JetA Oxidation, WD2 CO Oxidation, Hydrogen Oxygen, Water Gas Shift, NO Formation JetA PDF END # #----------------------------------------------------------------------- # Fuel Oxidation Reactions #----------------------------------------------------------------------- # # One Step # REACTION: JetA Oxygen WD1 Option = Single StepReaction Description = Rate for C10H22 scaled by molar mass (W&D, 1981) REACTANTS: Materials List = JetA, O2 Option = Child Materials CHILD MATERIAL: JetA Option = Stoichiometric Reaction Order = 0.25 Stoichiometric Coefficient = 1.0 END CHILD MATERIAL: O2 Option = Stoichiometric Reaction Order = 1.5 Stoichiometric Coefficient = 17.75 END END PRODUCTS: Materials List = CO2, H2O Option = Child Materials CHILD MATERIAL: CO2 Option = Stoichiometric Stoichiometric Coefficient = 12.0 END CHILD MATERIAL: H2O Option = Stoichiometric Stoichiometric Coefficient = 11.5 END END FORWARD REACTION RATE: Option = Arrhenius Pre Exponential Factor = 144.0/167.0 * 3.8E+11 [s^-1 mol^-0.75 cm^2.25] Temperature Exponent = 0 REACTION ACTIVATION: Option = Activation Energy Activation Energy = 30 [kcal mol^-1]END END END # # Two Step # REACTION: WD2 JetA Oxidation Option = Single Step Reaction Description = Rate for C10H22 scaled by molar mass (W&D, 1981) REACTANTS: Materials List =JetA, O2 Option = Child Materials CHILD MATERIAL: JetA Option = Stoichiometric Reaction Order = 0.25 Stoichiometric Coefficient = 1.0 END CHILD MATERIAL: O2 Option = Stoichiometric Reaction Order = 1.5 Stoichiometric Coefficient = 11.75 END END PRODUCTS: Materials List = CO, H2O Option = Child Materials CHILD MATERIAL: CO Option = Stoichiometric Stoichiometric Coefficient = 12.0 END CHILD MATERIAL: H2O Option = Stoichiometric Stoichiometric Coefficient = 11.5 END END FORWARD REACTION RATE: Option = Arrhenius Pre Exponential Factor = 144.0/167.0 * 4.7E+11 [s^-1 mol^-0.75 cm^2.25] Temperature Exponent = 0 REACTION ACTIVATION: Option = Activation Energy Activation Energy = 30 [kcal mol^-1] ENDEND END # # Water/Gas Shift # REACTION: WD3 JetA Oxidation Option = Single Step Reaction Description = Rate for C10H22 scaled by molar mass (W&D, 1981) REACTANTS: Materials List = JetA, O2 Option = Child Materials CHILD MATERIAL: JetA Option = Stoichiometric Reaction Order = 0.25 Stoichiometric Coefficient = 1.0 END CHILD MATERIAL: O2 Option = Stoichiometric Reaction Order = 1.5 Stoichiometric Coefficient = 6.0 END END PRODUCTS: Materials List = CO, H2 Option = Child Materials CHILD MATERIAL: CO Option = Stoichiometric Stoichiometric Coefficient = 12.0 END CHILD MATERIAL: H2 Option = Stoichiometric Stoichiometric Coefficient = 11.5 END END FORWARD REACTION RATE: Option = Arrhenius Pre Exponential Factor = 144.0/167.0 * 8.0E+11 [s^-1 mol^-0.75 cm^2.25] Temperature Exponent = 0 REACTION ACTIVATION: Option = Activation Energy Activation Energy = 30 [kcal mol^-1] END END END # #----------------------------------------------------------------------- # NO Formation #----------------------------------------------------------------------- # REACTION: NO Formation JetA PDF Reaction Description = NO Formation with Temperature PDF for JetA Option = Multi Step Reactions List = Thermal NO PDF, Prompt NO JetA PDF END # REACTION # # Prompt NO # REACTION: Prompt NO JetA PDFReaction Description = Prompt NO by JetA with Temperature PDF (rate from CH4) Option = Single Step REACTANTS: Option = Child Materials Materials List = O2, N2, JetA CHILD MATERIAL: O2 Option = Stoichiometric Stoichiometric Coefficient = 0.5 Reaction Order = 0.5 END CHILD MATERIAL: N2 Option = Stoichiometric Stoichiometric Coefficient = 0.5 Reaction Order = 1.0 END CHILD MATERIAL: JetA Option = Stoichiometric Stoichiometric Coefficient = 0.0 Reaction Order = 1.0 END END PRODUCTS: Option = Child Materials Materials List = NO CHILD MATERIAL: NO Option = Stoichiometric Stoichiometric Coefficient = 1.0 END END FORWARD REACTION RATE: Option = Arrhenius with Temperature PDF Lower Temperature = 300 [K] Upper Temperature = 2300[K] Temperature Exponent = 0 Pre Exponential Factor = 6.4E+6 [s^-1] * (mw/density)^1.5 REACTION ACTIVATION: Option = Activation Temperature Activation Temperature = 36510 [K] END END COMBUSTION MODEL: Option = Finite Rate Chemistry END END # REACTION # END |
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