[boundarylayer]

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 it’s 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]

Any help would be great

[sreerao]

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

[Goky]

Hi friends. I am trying to do numerical simulation in a ramjet combustor using non-premixed and DPM models. Could anyone guide me to obtain results for this analysis? How to inject fuel in front of flame holders and how to start the combustion process?

Thank you

[Foxhunter]

Originally Posted by Goky

Hi friends. I am trying to do numerical simulation in a ramjet combustor using non-premixed and DPM models. Could anyone guide me to obtain results for this analysis? How to inject fuel in front of flame holders and how to start the combustion process?

Thank you

This thread is 7 years old... you should probably not hijack threads from 2010, just make your own. Having said that, you can define in inlet in the meshing stage of Fluent, and in the simulation part of Fluent give it an velocity of mass flow value. Then, in the Species tab, set the fuel to 1. For the air inlet set it to 0 in Species, if you defined a second stream as air it automatically using air then. For the start of the combustion process you can define a high temperature region, or use the Spark ignition model. That model should be under Setup>Models>Species>Spark Ignition if I'm not mistaken.

[Goky]

Hi Foxhunter. Though this is a 7 years old thread, I am starting this problem now. I thank you for your answer.