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Add ignition but combustion does not occur

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Old   January 14, 2014, 23:01
Default Add ignition but combustion does not occur
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Hi, I am trying to do some simulation about the combustion of isooctane. I use reactingFoam which includes chemkin of isooctane. For the ignition, I add fvOptions in the system. The ignition during is 0.001s. However, the maximum temperature goes up during the ignition and goes down very quickly after the ignition which means no combustion occurs. So, could anyone gives me some advice how to deal with this problem. Thanks in advance.
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Old   January 18, 2014, 08:52
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Bobi
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Greetings zhuguangfei

For having combustion, first you should clarify your combustion model in O.F.
If you are using PaSR model (I guess), Raise the temperature of the fuel stream upper than auto-ignition temperature, after starting the combustion, change it to normal temperature in the boundary condition of your T file. There is no need to use ignition.
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Bobi
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Old   January 18, 2014, 15:16
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Quote:
Originally Posted by babakflame View Post
Greetings zhuguangfei

For having combustion, first you should clarify your combustion model in O.F.
If you are using PaSR model (I guess), Raise the temperature of the fuel stream upper than auto-ignition temperature, after starting the combustion, change it to normal temperature in the boundary condition of your T file. There is no need to use ignition.
Regards
Bobi
Hi, Bobi

First, thanks for your kind reply. My initial temperature is 330 K and the boundary condition is wall boundary. That means the mixture is homogeneous. Then I add an ignition (fvOptions). You are right that I choose PaSR combustion model. So,I just guess maybe the ignition duration is too small which means the diffusion overcomes the injection energy leading to extinguish. By the way, could you tell me the meaning of
injectionRateSuSp
{
h (10, 0)
}
in the fvOptions? Thanks so much.
Best Regards,
Colin
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Old   January 19, 2014, 02:43
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Greetings zhuguangfei

Unfortunately, I don't use ignition for having combustion with PaSR combustion model. I think that is a source term for enthalpy in enthalpy equation that causes a sudden increase in temperature.

I think my suggestion was not enough transparent. After starting injecting your fuel stream with a Temp more than 2000 K , you will have combustion automatically. After passing a while, save your result and in the temperature file change your fuel stream temperature to 300 K. This is the way that we start combustion in PaSR model without using ignition.

Regards
Bobi
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Last edited by babakflame; January 19, 2014 at 10:35.
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