Asymptotic theory of diffusion-flame extinction in the stagnation-point boundary layer☆

Abstract An analysis is developed for predicting extinction of the diffusion flame that is established when an oxidizing gas flows about the nose of a vaporizing fuel body. Use is made of the limit of a large ratio of the activation energy to the thermal energy at the flame for the overall combustion process, since this limit encompasses all cases of practical interest. By revealing a correspondence with the asymptotic flame structure of a counterflow diffusion flame analyzed earlier, the theory makes available explicit formulas, in term of a Damkohler number, for study of gas-phase extinction in the present geometry. From these results a simplified but reasonably accurate method is developed for obtaining, from experimental data on extinction, kinetic information concerning the overall oxidation process occurring in the vicinity of extinction. Curves calculated from a parametric study are presented to facilitate application of the technique, and the procedure is illustrated for methanol burning in oxygennitrogen mixtures.