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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