Construction of a reduced mechanism for modelling premixed combustion of methane–air

Abstract

The current study has identified a useful reduced mechanism that can be used to simulate the combustion of natural gas in computational fluid dynamic (CFD) code. This reduced mechanism can lower the computational cost and process of accurately predicting the overall flame structure, including gas temperature and radical intermediate species such CH₃, CO and NO_x. In the present study the fully automatic algorithm S-STEP, which is based on the computational singular perturbation (CSP) method, has been used to construct the reduced mechanism. Input-required data for this algorithm include the detailed mechanism, a numerical solution of the problem and the desired number of global reactions in the reduced mechanism developed in this work. The analysis is performed on the solution of laminar mono-dimensional premixed flame with detailed mechanism GRI-3.0. A reduced mechanism with ten global reactions for methane combustion has been constructed. The numerical results which were obtained, for different values of the equivalence ratio (ϕ = 0.6 and ϕ = 1.0), on the basis of this reduced mechanism, were compared with those computed on the basis of the detailed mechanism GRI-3.0. The developed ten-step mechanism produces, with accuracy, similar results in comparison with the results obtained by detailed mechanism GRI-3.0. The agreement between these two results is reasonable since the reduced mechanism obtained in this study can give a good approximation of the original massive reaction system both qualitatively and quantitatively.