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ignition of premixed flame

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Old   May 25, 2004, 06:54
Default ignition of premixed flame
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tilman
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Hi everybody,

I am trying to calculate a laminar premixed methane-air flame (equivalence ratio =1.0). According to the fluent manual the ingnition is done just by patching a volume within the flow domain with a high temperature. When I am doing it in this way, my mixture does not ignite. Has anybody an idae what might be my mistake? Do I miss anything?

I am using the generalized finite-rate model with activated volumetric reactions.

please let me know if you need any more info to answer my question.

Thanks in advance, Tilman
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Old   June 1, 2004, 22:39
Default Re: ignition of premixed flame
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Arun
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did you make sure that you were patching the right amount of pressure and temperature to ignite the mixture? If your flow has an inlet, then patching should include proper values of temperature and pressure as the velocity of the incoming flow could just wash out the initial condition of high pressure and temperature. All the best.

Arun
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Old   June 24, 2009, 05:19
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divyam
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hi tilman

did your problem get solved. i too want to know how to ignite premixed flames
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Old   June 24, 2009, 06:15
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hi divyatman,

You can try a couple of tricks. One is initializing your calculations with high temperature, other is increasing temperature on one of the walls at the inlet. Once you have an ignition you can lower the wall temperature. This works for steady state solution.
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Old   June 24, 2009, 06:26
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divyam
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thanks a lot

did you also use species transport model with Laminar finite rate interaction while using these tricks?
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Old   June 24, 2009, 07:18
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Actually, I usually simulate turbulent flames but I think it should work with laminar flames as well.
If it works you can update this thread
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Old   June 25, 2009, 04:40
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Somehow initializing with high temperature didn't work for me.

i was able to ignite the flame using patch method as described in Fluent manuals.

Problem i get now is that the size of region i select for patching high temperature value affects my final solution. the region consisting of burnt products extends to the end of patched region. Shouldn't it be independent of that?

if you have had similar experience let me know.
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