The propagation and inhibition of an exothermic branched-chain flame with an endothermic reaction and radical scavenging

Abstract

The effects of the endothermic decomposition of an inhibitory species W to form a radical scavenger on a laminar, pre-mixed flame supported by an exothermic second-order branching reaction are considered. This work extends a previous study, where the effects of the radical scavenger S were ignored. Two cases are identified, dependent on a parameter β measuring the relative rate of the decomposition of W. These are described by an high-activation-energy asymptotic analysis and through numerical integration of the propagating-flame equations for representative parameter values. For larger values of β the effect of the radical scavenger is to introduce a critical value of the heat-loss parameter α for flame propagation. For smaller values of β, where there is a critical value of α without any S being produced, the effect is to lower this critical value. In both cases the effect of the radical scavenger is to reduce the propagation speed and, if sufficient amounts of S are produced from the decomposition of W, to totally suppress flame propagation, even without any heat loss.