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-   -   Combustion in a closed System (https://www.cfd-online.com/Forums/fluent/45079-combustion-closed-system.html)

 Martin Castillo June 18, 2007 23:00

Combustion in a closed System

Hello Everyone,

(Sorry the last post was difficult to read so I am posting again.)

I am new to Fluent and have been doing some modeling recently. I am studying the combustion of air and hydrogen in a closed chamber. My 2-D mesh looks like a donut with an inner radius of .3mm and outer of 50mm and this has been cut in half for symmetry purposes. I am having trouble modeling in a closed chamber and hope you can help me out. There was a bit of information given on 2004 by someone with the name of Jim (Combustion in a closed system, Posted By: Jim, Date: Mon, 6 Dec 2004, 12:10 p.m.). I would like to start my combustion of the gas at the small inner diameter "hot-wire". This surface should be somewhere from 875 to 1300 deg C. I have done the following procedure to accomplish this and then at the end I am unable to define the temperature of the hot-wire and chamber wall.

 Grid->Check

 Grid->Scale->mm->Scale->Close

 Define->Models->Viscous->K-epsilon(2eqn)->OK

 Define->Models->Species->Premixed Combustion->Apply->Ok to the warning->Ok

 Define->Materials->Fluent Database->Then I picked out air and hydrogen->changed absorbtion coefficient to 10 for both of them and each time clicked on Change/Create->Close

 Define->operating conditions->Checked Gravity->Y=-9.8->ok

 Define->Boundary Conditions->Hot Wire->###Can't define temperatures here###

Any ideas suggestions are appreciated. If you need further information please email me at macastil@mines.edu.

Thanks, Dr. Martin Castillo

 Martin Castillo June 19, 2007 01:33

Re: Combustion in a closed System

Sorry, I believe that you have to move out of the Adiabatic regime to the Non-Adiabatic regime.

 Neil June 20, 2007 08:33

Re: Combustion in a closed System

Did you enable the energy equation?

 Martin Castillo June 20, 2007 21:38

Re: Combustion in a closed System

Hello Neil, Thanks for your fast response. The energy equation was automatically enabled by the radiation model and changing the parameter to non-adiabatic conditions. Just to be safe, I did go back and make sure it was enabled. My main mistake was not enabling non-adiabatic conditions. Thanks for your help. -Martin

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