Some properties of nearly premixed laminar flame propagation along weakly stratified layers in combustible gas mixtures

Abstract

Nearly premixed laminar flame propagation along weakly stratified layers in combustible gas mixtures is examined theoretically in the limit of weak flame stretch, high activation energy, and unity Lewis number. The stratification is represented by the variation in flame temperature along the reaction zone. Stratification is shown to affect the propagation velocity by a convective loss mechanism and by a diffusive mechanism that could be termed flame thickening. Whether a given amount of stratification should be expected to increase or decrease the propagation velocity compared with that of a nonstratified mixture depends on the angle the flame makes to the flow. The propagation velocity is most sensitive to the stratification for small flame angles.