Simulation of laminar methane-air flames using automatically simplified chemical kinetics

The method of intrinsic low-dimensional manifolds to simplify chemical kinetics is applied to laminar methane-air flames. The procedure is based on a mathematical analysis of the reaction system. Neither steady state assumptions for some species, nor partial equilibrium for reactions have to be specified explicitly. The only requirements to the scheme are a derailed reaction mechanism and the number of degrees of freedom desired for the simplified scheme. All necessary information on the thermochemical state (species concentrations, temperature, density, etc.) is then given as function of a small number of reaction progress variables, associated with the degrees of freedom. Therefore, less equations (for two or three reaction progress variables instead of for 34 species in case of CH4) have to be solved, thus drastically reducing the computational effort compared to calculations using detailed chemistry. Subsequent use of a tabulation procedure, where all information is stored, guarantees an efficient use in various CFD applications.