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-   -   CFD simulation of a ramjet combustion chamber (http://www.cfd-online.com/Forums/fluent/78929-cfd-simulation-ramjet-combustion-chamber.html)

boundarylayer August 6, 2010 02:26

CFD simulation of a ramjet combustion chamber
 
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Hi CFD colleague,

I just wanted to know if anyone has tried to simulate the combustion chamber of a ramjet engine and how they went about getting combustion to occur as I need it for my final year project. The geometry is supplied at the bottom.

Of interest also is what boundary conditions were used, is it best to define injectors or use a velocity inlet for the fuel injectors. I'm using a velocity inlet of 100m/s for the air, is this too high and a mass flow rate for the fuel.
Further is best to perform a transient analysis or a steady state?

Is an ignition source required and how do you define it as itís not in any of the tutorials.

Further is there a way to have two separate fluids say air and a jet A fuel and do you define this. If i create a mixture there is no option to use jetA with air but you can get them as two separate fuels in the Fluent database. I have been using a mixture of air and methane at the moment but cant get combustion to occur.

I really would appreciate any form of help with any of the above questions.

Best regards
Boundarylayer

boundarylayer October 17, 2010 00:11

Any help would be great

sreerao October 19, 2010 10:47

Hi

I am assuming it is liquid fuel ramjet and the combustion is subsonic. First you should try to establish fuel inlet. Let us imagine, it is liquid spray in your original ramjet (exeriment), I would go for injecitons with certain properties.

Furthermore you did not mention is it 2d or 3d simulaitons. Any simulaitons, I would start with steady and would go for unsteady at a later stage. Since it is a diffusion based combustion, I may choose pressure-based solver initially. Just check for the significant variations of the density, it they exsist you should choose density based solver.

yes, you should patch a high temperature region in your combustor to start flame. make sure fuel air ratio is combustable or not.

Regards
Sree


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