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-   -   Modelling Combustion in Porous Zone (http://www.cfd-online.com/Forums/fluent/82209-modelling-combustion-porous-zone.html)

tanjinjack November 19, 2010 12:23

Modelling Combustion in Porous Zone
 
Hi,

I am having problems in defining combustion in porous zone and will appreciate any inputs.

I am a student in Malaysia, currently working on a design project. I am assigned in building a simulation model of porous burner. It will consist of a mass flow inlet, which it will enter a porous zone where combustion is ignited. After the porous zone, the temperature will be observed. They are defined into three fluid zone, 'before porous', 'porous zone' and 'after porous'.

Being a beginner in FLUENT and CFD, I find this tough and challenging at the same time as I need to learn two new things - defining porous zone and using a combustion model. BTW, I touched a little bit of CHEMKIN and thus have ideas of the mechanism files etc.

After some studies, I manage to define my porous zone correctly (as I see velocity slowing down) and I found the necessary equations to define the inertial and viscous losses, yet to compute the value I need though.

However, I am having issues with defining the combustion and FLUENT user guide does not help beyond my problem.
I intend to use the pre-mixed combustion model but will take advice on choosing the partially pre-mixed model if necessary.

My problem is that:
  1. I am unsure if I really initiate any combustion. I don't think I came across choosing my fuel and oxidiser, although I tried to define the zones into 'methane'.
  2. However, I observe a change of progress variable. Does that mean combustion actually occurs?
  3. I also try to 'patch' the progress variable so that I think it would only start combustion in the porous zone, but the contour of progress variable (and also product formation rate) does not show that the combustion confines within the porous zone I define. I have then been patching blindly and through trial and error and it doesn't seem I am getting it correct.

Do I miss out anything important? I was reading FLUENT user guide and saw reaction could be defined in porous zone. I think I overlooked it in FLUENT or it isn't there for me to choose from the beginning.
I am away from my university currently and will only be able to access FLUENT by Monday. But certainly, I wish to collect as many ways of doing it as possible now so that I can run it when I reach my university on Monday.

Kindly direct me to any literature that you think might help me. Even if I can't access it from my home, I could grab and read it when I reach my university.

:confused:


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