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Methane+air temperature too high

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Old   June 1, 2004, 16:07
Default Methane+air temperature too high
  #1
Stanislav Kraev
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Could anybody tell me, why resulting temperature of methane combustion is too high (>2000K). I used several turbulent models (results are quite similar), Species Transport model and standard chemical models form fluent library. Radiation doesn't change the temperature a lot.
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Old   June 1, 2004, 21:30
Default Re: Methane+air temperature too high
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Arun
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Hi Stanislav,

Try doing the 2-step reaction. One step reaction might give an over prediction of temperature. All the best.

Arun
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Old   June 2, 2004, 01:43
Default Re: Methane+air temperature too high
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Stanislav Kraev
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Yeah. I tried 2-step reaction. Temperature still >2000K.
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Old   June 2, 2004, 02:36
Default Re: Methane+air temperature too high
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Arun
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Did you try changing the grid? Sometimes grid resolution can also show variations in the solution. Also look at the time step of your reaction carefully. Sometimes the code might be stable for large time steps but will not give you the right solution. All the best.

Arun
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Old   June 2, 2004, 02:50
Default Re: Methane+air temperature too high
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Stanislav Kraev
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Thanks. I think I found where the problem was. I used velocity inlets (don't know why ). Tested pressure inlets and it's ok now (~1300K). Grid resolution was quite good and I used stationary case. If somebody want to tell something about my problem, it would be cool! See you.
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Old   June 3, 2004, 10:54
Default Re: Methane+air temperature too high
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zxaar
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follow the tutorial , in that they mention if they modify the CP to polynomial fit rather than constant , the temperature it predicts is less that what u otherwise get
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