Prediction of propagating laminar flames in methane, oxygen, nitrogen mixtures

Abstract

An unsteady-state, one-dimensional, flame propagation model was used to study the characteristics of methane oxygen and methane air flames. The transformed species and energy concervation equations were solved with a numerical computer solution proposed by Spalding [1]. The diffusion model employed is based on the Chapman-Enskog kinetic theory and the development of Mason, Monchick and co-workers [2–6] for polyatomic gas mixtures containing one polar component. A methane oxygen reaction mechanism consisting of 29 elementary reactions was used in the flame model. The effects of equivalence ratio, pressure, initial temperature, and transport coefficients on the flame velocity, flame thickness, temperature profile, and concentration profiles were investigated for a series of methane air flames. Many of the model predictions were compared with experimental data. Some of the chemical kinetic data were selected or slightly modified in order to improve the agreement between calculated and measured values, which was good, when the final set of rate coefficients was used. The relative importance of each of the 29 elementary reactions was examined. The concentrations of the radicals H and OH were major factors in determination of flame characteristics.