Parametric study of nitrogen oxide formation during combustion of uniform methane-air mixtures

With a model for the propagation of normal flame fronts in methane-air mixt ures as an example, estimates are made of the contribution of various NOx f ormation mechanisms with varying pressure, temperature, and mixture composi tion. During combustion of near stoichiometric mixtures, the thermal mechan ism is found to predominate, while in lean mixtures, the N2O mechanism pred ominates and in rich mixtures, the "prompt" mechanism. These results are co mpared with a direct solution of the kinetic problem and it is shown that t his simpler model provides a satisfactory description of NO2 formation in l ean and nearly stoichiometric flames.