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-   -   reactingFoam: adiabatic flame temperature (http://www.cfd-online.com/Forums/openfoam/66952-reactingfoam-adiabatic-flame-temperature.html)

rFkhemek July 29, 2009 06:22

reactingFoam: adiabatic flame temperature
 
Hello,

I am using reactingFoam for simulation of premixed laminar flames. I noticed that the maximum flame temperature continues to increase much beyond adiabatic flame temperature.

Does anyone have idea why this is happening?

Frederick

chbenz July 31, 2009 04:11

Hi,

could you tell us a bit more of your case setting?

Christof

rFkhemek July 31, 2009 06:42

rxn mech.
 
Christof,

I just noticed that this problem of flame temperature (FT) peeking to 4000 K & above is something not specific only to the case with new reaction mechanism. I ran the reactingFoam tutorial case for heptane, and without exception FT is again increasing uncontrollably.

Pasted below is the output for a few i.steps:

Solving chemistry
diagonal: Solving for rho, Initial residual = 0, Final residual = 0, No Iterations 0
DILUPBiCG: Solving for Ux, Initial residual = 0.000106553, Final residual = 3.70098e-08, No Iterations 1
DILUPBiCG: Solving for Uy, Initial residual = 0.000307872, Final residual = 1.29959e-07, No Iterations 1
DILUPBiCG: Solving for C7H16, Initial residual = 0.000136574, Final residual = 3.75731e-08, No Iterations 1
DILUPBiCG: Solving for O2, Initial residual = 1.15028e-05, Final residual = 4.19287e-08, No Iterations 1
DILUPBiCG: Solving for CO2, Initial residual = 5.6045e-05, Final residual = 3.30845e-08, No Iterations 1
DILUPBiCG: Solving for H2O, Initial residual = 5.6045e-05, Final residual = 3.30845e-08, No Iterations 1
DILUPBiCG: Solving for h, Initial residual = 0.000146672, Final residual = 4.47212e-08, No Iterations 1
DICPCG: Solving for p, Initial residual = 0.0098115, Final residual = 8.23315e-10, No Iterations 94
diagonal: Solving for rho, Initial residual = 0, Final residual = 0, No Iterations 0
time step continuity errors : sum local = 1.37979e-13, global = 5.5059e-16, cumulative = 4.67128e-13
DICPCG: Solving for p, Initial residual = 0.000684229, Final residual = 9.72282e-10, No Iterations 80
diagonal: Solving for rho, Initial residual = 0, Final residual = 0, No Iterations 0
time step continuity errors : sum local = 1.28656e-13, global = -1.25894e-15, cumulative = 4.65869e-13
DILUPBiCG: Solving for epsilon, Initial residual = 2.20208e-05, Final residual = 3.70251e-09, No Iterations 1
DILUPBiCG: Solving for k, Initial residual = 8.20206e-05, Final residual = 2.26324e-08, No Iterations 1
ExecutionTime = 3027.24 s ClockTime = 3034 s

Max Temperature = 5004.46 K

Density = 1.50653 kg/m3

h Value = 537143 J/kg/K

Courant Number mean: 0.0145809 max: 0.0987632
deltaT = 2.43902e-05
Time = 0.0831951

Solving chemistry
diagonal: Solving for rho, Initial residual = 0, Final residual = 0, No Iterations 0
DILUPBiCG: Solving for Ux, Initial residual = 0.000116581, Final residual = 3.36492e-08, No Iterations 1
DILUPBiCG: Solving for Uy, Initial residual = 0.000437282, Final residual = 1.29249e-07, No Iterations 1
DILUPBiCG: Solving for C7H16, Initial residual = 0.000136563, Final residual = 3.7544e-08, No Iterations 1
DILUPBiCG: Solving for O2, Initial residual = 1.14962e-05, Final residual = 3.73572e-08, No Iterations 1
DILUPBiCG: Solving for CO2, Initial residual = 5.60065e-05, Final residual = 3.38653e-08, No Iterations 1
DILUPBiCG: Solving for H2O, Initial residual = 5.60065e-05, Final residual = 3.38653e-08, No Iterations 1
DILUPBiCG: Solving for h, Initial residual = 0.000146659, Final residual = 4.46909e-08, No Iterations 1
DICPCG: Solving for p, Initial residual = 0.021823, Final residual = 7.99519e-10, No Iterations 94
diagonal: Solving for rho, Initial residual = 0, Final residual = 0, No Iterations 0
time step continuity errors : sum local = 1.39516e-13, global = 6.78508e-16, cumulative = 4.66548e-13
DICPCG: Solving for p, Initial residual = 0.0010358, Final residual = 8.53631e-10, No Iterations 78
diagonal: Solving for rho, Initial residual = 0, Final residual = 0, No Iterations 0
time step continuity errors : sum local = 1.2852e-13, global = -3.65466e-16, cumulative = 4.66182e-13
DILUPBiCG: Solving for epsilon, Initial residual = 2.1987e-05, Final residual = 3.94527e-09, No Iterations 1
DILUPBiCG: Solving for k, Initial residual = 8.18932e-05, Final residual = 2.20388e-08, No Iterations 1
ExecutionTime = 3028.26 s ClockTime = 3035 s

Max Temperature = 5004.55 K

Density = 1.50653 kg/m3

h Value = 537143 J/kg/K

Courant Number mean: 0.0145802 max: 0.0987639
deltaT = 2.43902e-05
Time = 0.0832195

Solving chemistry
diagonal: Solving for rho, Initial residual = 0, Final residual = 0, No Iterations 0
DILUPBiCG: Solving for Ux, Initial residual = 0.000114486, Final residual = 3.12228e-08, No Iterations 1
DILUPBiCG: Solving for Uy, Initial residual = 0.000386029, Final residual = 1.17461e-07, No Iterations 1
DILUPBiCG: Solving for C7H16, Initial residual = 0.000136565, Final residual = 3.75133e-08, No Iterations 1
DILUPBiCG: Solving for O2, Initial residual = 1.14759e-05, Final residual = 3.74779e-08, No Iterations 1
DILUPBiCG: Solving for CO2, Initial residual = 5.60046e-05, Final residual = 3.35481e-08, No Iterations 1
DILUPBiCG: Solving for H2O, Initial residual = 5.60046e-05, Final residual = 3.35481e-08, No Iterations 1
DILUPBiCG: Solving for h, Initial residual = 0.000146682, Final residual = 4.46701e-08, No Iterations 1
DICPCG: Solving for p, Initial residual = 0.0181925, Final residual = 9.03279e-10, No Iterations 90
diagonal: Solving for rho, Initial residual = 0, Final residual = 0, No Iterations 0
time step continuity errors : sum local = 1.36605e-13, global = 1.02321e-15, cumulative = 4.67205e-13
DICPCG: Solving for p, Initial residual = 0.000779756, Final residual = 9.12506e-10, No Iterations 75
diagonal: Solving for rho, Initial residual = 0, Final residual = 0, No Iterations 0
time step continuity errors : sum local = 1.26039e-13, global = 3.33582e-16, cumulative = 4.67539e-13
DILUPBiCG: Solving for epsilon, Initial residual = 2.19667e-05, Final residual = 3.60779e-09, No Iterations 1
DILUPBiCG: Solving for k, Initial residual = 8.18277e-05, Final residual = 2.25868e-08, No Iterations 1
ExecutionTime = 3029.38 s ClockTime = 3036 s

Max Temperature = 5004.64 K

Density = 1.50653 kg/m3

h Value = 537143 J/kg/K

Courant Number mean: 0.0145796 max: 0.0987648
deltaT = 2.43902e-05
Time = 0.0832439




Frederick


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