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July 14, 2017, 06:00 |
No flames from PaSR combustion model
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#1 |
Senior Member
Join Date: Jan 2013
Posts: 372
Rep Power: 14 |
Hi All,
I tried to use PaSR to calculate a simple jet flame, firstly used infinitelyFastChemistry model to obtain an fully burning jet flame field, which seem reasonable. Then I changed the combustion model to PaSR, and if course changed other PaSR related parameter. When the simulation goes, the flame is convected downstream and finally it become just cold. What is the problem for the simulation? Anybody also has this experince? I put my combustionProperties, chemistryProperties and reactions below: Code:
combustionModel PaSR<rhoChemistryCombustion>; active true; infinitelyFastChemistryCoeffs { semiImplicit no; C 10; } laminarCoeffs { } noCombustionCoeffs { } PaSRCoeffs { Cmix 1.0; turbulentReaction yes; // useReactionRate true; } Code:
chemistryType { chemistrySolver ode; //EulerImplicit; chemistryThermo rho; } chemistry on; initialChemicalTimeStep 1e-07; EulerImplicitCoeffs { cTauChem 1; equilibriumRateLimiter off; } odeCoeffs { solver Rosenbrock34; absTol 1e-12; relTol 0.01; } Code:
species ( CH4 CO CO2 H2 H2O O2 N2 ); reactions { //- for infinite fast reaction model // methaneReaction // { // type irreversibleinfiniteReaction; // reaction "CH4 + 2O2 + 7.5N2 = CO2 + 2H2O + 7.5N2"; // } //- for PaSR combustion model methaneReaction { type irreversibleArrheniusReaction; reaction "CH4 + 2O2^1.0 = CO2 + 2H2O^1.0"; A 7e+06; beta 0; Ta 10063.8; } hydrogenReaction { type irreversibleArrheniusReaction; reaction "H2 + 0.5O2^1.0 = H2O"; A 4.74342e+12; beta 0; Ta 10063.8; } } |
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July 14, 2017, 07:02 |
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#2 | |
Senior Member
Join Date: Jan 2013
Posts: 372
Rep Power: 14 |
Problem solved. The activation energy is too small, so that the reaction is so weak.
Quote:
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September 27, 2017, 02:50 |
PaSR
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#3 |
Member
Zhiheng Wang
Join Date: Mar 2016
Posts: 72
Rep Power: 10 |
Use c= 0 to minimize the turbulent and laminar reaction time scale it must be low reynolds no case try c = in combustion PaSR directory.
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