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-   -   Hydrogen-Air Non-Premixed Combustion (http://www.cfd-online.com/Forums/fluent/50642-hydrogen-air-non-premixed-combustion.html)

Wasim February 21, 2009 16:24

Hydrogen-Air Non-Premixed Combustion
 
Hello there, I am working on simulating hydrogen-air non-premixed combustion. I am having problems in attaining good results. My set-up includes a jet of hydrogen at 900K (to allow for auto-ignition) flowing into a still enviroment at 300K (working fluid by default - air). I have modelled the problem using non-premixed combustion model. The contours of static temperatures does not show an increase in temperature; in other word, I cannot see the flame (which tells me that combustion does not take place). I have even tried patching the fluid to a temperature of about 2000K, but nothing seems to work out. Please help me out! The deadline for the work is due in for the 3rd of March, 2009. I would really appreciate your help.

Thanks

Ev February 22, 2009 16:01

Re: Hydrogen-Air Non-Premixed Combustion
 
Hi Wasim,

I am working on the similar problem of nonpremixed combustion, but the fluids are air and methane. I just started my project and I am a beginner in Fluent. Could you please tell give me an idea that for nonpremixed combustion, what viscous models and other parameters do I need to select?

Thank you so much.


Wasim February 22, 2009 17:14

Re: Hydrogen-Air Non-Premixed Combustion
 
Non-premixed combustion model in fluent is most suitable for turbulent diffusion flames. Hence I suggest you start off with k-epsilon standard model and have the default values for k and e (which is 1). Those are the value I chose anyway. The modelling process is quite straight forward, but i am just stuck because ignition does not seem to take place in my place. Anyways Good luck!

Regards,

Wasim

Ev February 22, 2009 18:03

Re: Hydrogen-Air Non-Premixed Combustion
 
Hello Wasim,

Thanks for replying. :)

Allan Walsh February 23, 2009 14:20

Re: Hydrogen-Air Non-Premixed Combustion
 
Are you using the built-in reaction mechanisms? What values are you getting for kinetic reaction rate? turbulent reaction rate? You can modify parameters if needed to get combustion started. The basic k-epsilon model for turbulence combined with eddy dissiptation model for combustion will not give a lot of insight into the flame structure, but should at least show something burning.

Wasim February 23, 2009 21:59

Re: Hydrogen-Air Non-Premixed Combustion
 
Since I was using non-premixed combustion model I do not have the choice to specify reaction mechanism. However, my simulation is now working and I think I have obtained good results (though I might be wrong). Thank you!

Regards,

Wasim

tsram90 March 21, 2012 05:44

Quote:

Originally Posted by Wasim
;156811
Since I was using non-premixed combustion model I do not have the choice to specify reaction mechanism. However, my simulation is now working and I think I have obtained good results (though I might be wrong). Thank you!

Regards,

Wasim


How did you correct this problem?? I am also having constant value for pressure and temperature

deepthishan February 5, 2013 04:27

Use k-e model but try giving turbulence and hydraulic diameter in boundary condition instead of giving values for k and e

bahramnourani June 13, 2013 03:48

Quote:

Originally Posted by Wasim
;156764
Hello there, I am working on simulating hydrogen-air non-premixed combustion. I am having problems in attaining good results. My set-up includes a jet of hydrogen at 900K (to allow for auto-ignition) flowing into a still enviroment at 300K (working fluid by default - air). I have modelled the problem using non-premixed combustion model. The contours of static temperatures does not show an increase in temperature; in other word, I cannot see the flame (which tells me that combustion does not take place). I have even tried patching the fluid to a temperature of about 2000K, but nothing seems to work out. Please help me out! The deadline for the work is due in for the 3rd of March, 2009. I would really appreciate your help.

Thanks

Dear Wasim

I define the excess air of fuel by selecting a suitable mass flow of air at the boundary condition of the Fluent software,but I see that by increasing the excess air of fuel the maximum temperature is increased!??
I expect that the adiabatic flame temperature is dropped down by increasing the excess air of fuel.
Please guide me that how can I define the excess air of fuel at the non premixed combustion model.

Thanks
Bahram


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