Theory of a Hydrogen–Oxygen Diffusion Flame Part II: Large Activation Energy Asymptotics

Abstract

—Three activation energies of comparable size are identified amongst the total of twelve that are present in a six-step reaction scheme for H₂-O₂ combustion. Unique scalings for the inner and outer variables in an asymptotic model of a streamwise diffusion flame are found, based on the large activation energy limit. The resultant maximum-temperature versus Damköhler-number relationship is like the middle branch of the familiar S-curve, although the flame is of the near-equilibrium reaction-broadened type. The significance of these results in relation to flame extinction and theoretical modelling is commented upon.