about reaction of pure oxygen and CH4 in fluent5.4

Devy

This message was posted some weeks ago.But I still don't know how to solve it.So I post it again.If you have a ideal,please let me know.Thank you.

Now I am studying TUT 8.in fluent mannul, "Chemical Mixing and Gas Combustion". I don't consider the reaction of air and CH4.I just consider the reaction of pure oxygen and CH4.So I remove the N2 from material pannel.I change the air as to oxygen in the boundary of air-inlet.And I use Cp calcualated by mixing law and put the piecewise-polynomials in for each species. I don't change the other model.

When the solution is converged,I found the temperature rised to 4800K.And this is not true.Theoretical values of combustion temperature can be obtained from industry standard thermochemical codes for pure oxygen and CH4.And the temperature is about 2800K.

I've tried everything I can imagine!!!

Would you give me some advice?

Thanks a lot, in advance......

Devy 2001.7.29