[Giunto94]

Hello Everyone,
I am Lorenzo and I am studying combustion systems using CFD.
I am facing a weird problem on the methane-air 2step mechanism implemented in Fluent. Using a finite-rate combustion model, this "2step" mechanism is actually composed of 3 reactions (the second one is reversible, so it is divided in forward and backward).
1) CH4+1.5O2 => CO + 2H2O
2) CO + 0.5O2 = CO2

This mechanism corresponds exactly to the Westbrook&Dryer (1981) one, where the second forward reaction depends on CO, O2 and H2O concentrations with reaction orders of 1, 0.25 and 0.5 respectively. The strange thing is that in Fluent methane-air 2 step mechanism, H2O appears in the products part of the second forward reaction, while it should be in the reagents part! Moreover, since Backward reaction is not activated, reaction orders of product species shouldn't be taken into account....Am I wrong?

Thanks in advance for you availability.
Lorenzo