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Jouch October 18, 2004 04:27

Very simple combustion problem.
Hi, I am having serious problems with what seems to be a very straight forward problem.

I have 2 inlets and an outlet. Very simple 2-D axisymmetric model. One inlet I have Oxygen and the other Hydrogen. O2/H2 ratio is about 3:1

I am using the Hydrogen/Air mixture template. I have a good model with very good residuals under non-reacting conditions. I have a well adapted mesh.

Problem: I apply a temperature patch to a region near the inlet. Solution runs and the temperature increases over 3000K as expected. After about 5000 or so iterations, the flowfield is cold and there is no longer a flame.

I cant work it out and would be extremely grateful of any assistance.


dumb October 21, 2004 02:57

Re: Very simple combustion problem.
what combustion model are you using ...

jouch October 21, 2004 21:40

Re: Very simple combustion problem.
Hi, I first tried the non-premixed with a pdf file. This was not succesful. The chamber pressure would not increase despite the fact I was constantly increasing the mass flux of propellants!? The only way I could increase the internal (chamber) pressure was to increase the pressure outlet (incrementally to avoid divergence) which is a very lengthy and seemingly incorrect way to do things.

Also crazy results using this approach....i.e. 120K Oxygen at 5.4MPa normally has a density around 1000kg/m but Fluent is telling me 20kg/m...!

So,now I am trying simply with the species transport model but so far no good.

Thanks for any feedback. Jouch

dumb October 21, 2004 22:12

Re: Very simple combustion problem.
i have a pretty good experience with combustion modeling, and have done lot of analysis with fluent so if you can send me a mail decribing 1. boundary conditions (and other required conditions) 2. fuel you plan to burn etc. leave the geomtery details, i shall be writing an email to you describing step by step what shall you do to get that done, i might write this on this saturday or sunday as i can't send emails from office (some secrecy fundas), my email is

jouch October 21, 2004 22:28

Re: Very simple combustion problem.
Hi again,

That would be great if you could make a brief step-by-step procedure as to what I must do...

That way I can also explain further as to exactly what I want to do. Implement a real gas UDRGM for O2 at supercritical conditions. I have had quite a bit of experience with the Fluent basics and I have read quite a lot in the manuals but to no avail.

I would be extremely appreciative of your assistance. I will write now. Regards, Jouch

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