A computational model for premixed methane-air flame structure and formation of thermal nitric oxide is presented. The flame structure model is based on new transformed one-dimensional conservation equations in the "reaction-progress variable (c) space". The thermal NO model is based on an extended version of the Zel'dovich mechanism. The chemical kinetic model is based on a three-step reaction mechanism. The main computed variables are species CH{sub}4, O{sub}2, H{sub}2O, CO{sub}2, CO, H{sub}2, NO and the sensible enthalpy (h{sub}s). Boundary conditions, at c=0 (unburned mixture) an c=1 (filly burned), are specified and finite difference equations are derived from the governing conservation equations by formal integration and are solved numerically by a Gauss-elimination iterative technique. Each flemelet is computed for fixed values of the equivalence ratio (Φ) and the dissipation rate of the reaction progress variable (χ) at atmospheric pressure. The computed results show that the flamelet structure and thermal NO are very sensitive to the equivalence ratio while the effect of χ is not appreciable. Moreover, the Zel'dovich mechanism seems to be sufficient, for thermal NO computations, with the reaction OH+N<=>NO+H being of much less importance. The burning velocity, for different for different equivalence ratios was deduced from the computed flemelet structure and assessed against available data for lean and rich methane-air mixtures.
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