Hello, My problem is high temperature (fluent 6.1.22 peak temp.2150K, experimental max.temp. 1350 K) methane diffusivity in methane combustion. Model features and chosen parameters: 3D,species transport, methane-air 2 step, eddy dissipation, k epsilon standart model, discrete ordinate radiation model, Materials ; mixture, incompressbible ideal gas, absorption coefficient : wsggm cell based, cp mixing law, Fluids (co2, co, o2, n, ch4, h2o and air), cp: piecewise polynomial, density and absorption coefficient: constant Boundary conditions: air and fuel velocity inlet,

Sincerely yours

Hello,

I would suggest you to try different models for chemistry (e.g. EDC, or non-premixed combustion models such as equilibrium presumed PDFs or laminar flamelets); maybe the eddy dissipation model is not suitable for your case.

If you get the same problems with other models maybe you should check operating and boundary conditions.

Best regards,

Ale

hello Ozer!

try to model chemistry with prepdf approach, but the two(2) step chemistry is less accurate than detailed chemistry (more intermediate species!!).

Thanks Ale;

I have tried before the things that you suggest, different models in chemistry and the other combustion models. I checked the operating and boundary conditions.I can not reduce the temperature. Best regards Özer

Thanks Abel;

I have tried before the things that you suggest, different models in chemistry. I can not reduce the temperature. Best regards Özer

2 step mechanism .and the model u have said, the temperature is always 800-900 degrees higher than what it should be (at least for methane case), you got to shift to other models like flamelet EDC ..and they both work fine with methane (i have done at least 12 different calculation with these models and results match well with experiment) ..if in ur case u do not get results, then check what u r doign wrong

Thanks zxaar;

I will try that EDC model.

Best regards

Özer

Hello zxaar; do ý have to use EDC with 2 step mechanism or multi step. ý don t have multi step and chemkin. if you have chemical mechanism prepared for methane in chemkin can you sent it to me. Thanks for your attention. ozaydin@ogu.edu.tr Best regards

for multistep mechanism, the prepdf folder (installed by fluent) has db folder this has some mechanisms , from here you can take multistep mechanism to run

Dear Ozer, Velocity profile plays an important role for combustion. I prefer you to check your inlet boundary conditions for both air and fuel, if all the combustion models that you have tried did not solve your high temperature problem.