Transient Extinction History of a Solid Fuel Diffusion Flame

Abstract

The transient extinction history of a diffusion flame in the stagnation-point boundary layer of a solid fuel is presented. The numerical analysis shows that dynamic extinction is possible by a rapid reduction of an environmental factor, such as Damkohler number or oxygen concentration. The extinction transition can be divided into two stages separated by a very short period of active onset of flame extinguishment. During the first stage, a quasi-steady gas flame is maintained. Then the flame diminishes swiftly in a fraction of the gas phase characteristic time, followed by the second stage, i.e., the slow cooling-down of the solid.