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Author Topic: Reaction yields ....  (Read 3086 times)

Amir

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Reaction yields ....
« on: August 15, 2012, 04:27:04 am »

Dear experts,

I'm new to FDS and pyroSim and I've faced a problem in my first simulation; really appreciate if you can help me.
In the mixture fraction model, the reaction stoichiometry is specified and seems that isn't affected via flow filed. i.e, I wanna assess the amount of soot generation in a case with different situation (e.g. different boundary conditions) but seems that if I use mixture fraction model, the amount of soot in each case is the same regardless of different situations. Now, should I use finite-rate model fro this purpose while it's not recommended for LES?!

Thanks in advance.  :)

Amir
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Charlie Thornton

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Re: Reaction yields ....
« Reply #1 on: August 15, 2012, 12:07:06 pm »

I'm told that changing the soot yield in the Byproducts tab of the Edit Reactions dialog should change what you see for soot yield in the results. When you change the model and expect to see different soot generation, what parameters are you changing?
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Amir

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Re: Reaction yields ....
« Reply #2 on: August 15, 2012, 12:28:58 pm »

Dear Charlie,

Thank you very much for your time.
Assume that there is a fire in a tunnel and I want to assess how much soot is generated when the jet fans deliver different mass flow rate in the tunnel. I think if I use mixture fraction model (where the soot yield is pre-defined) I'll get the same result (total soot generation) for all of them. Am I right? Is there any way to solve that except using finite rate model?

Thanks again

Amir
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Charlie Thornton

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Re: Reaction yields ....
« Reply #3 on: August 15, 2012, 01:41:33 pm »

I don't know. My intuition says that if your fire is starved for air in one model and in another you give it more air that you should get different amounts of soot. Maybe somebody else around here knows how that should work (re: mixture fraction and finite rate) because I really don't. If you haven't already made some small test models to investigate this feature, I'd recommend doing so.

If you don't get any good answers here, another place to try that is better with questions about how FDS works is the FDS-SMV discussion group:

https://groups.google.com/group/fds-smv/topics
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Amir

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Re: Reaction yields ....
« Reply #4 on: August 15, 2012, 01:47:01 pm »

Thank you.
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