PREMIXED FLAMES WITH NONBRANCHING CHAIN-REACTIONS (STRUCTURE AND DYNAMICS)

A description of the flame structure, and its response to wrinkling and unsteady perturbations, is given for a simplified multiple step reaction mechanism (representative for example of halogen-hydrogen reactions), involving a dissociation reaction, a nonbranching chain reaction, both with high activation energy, and a recombination reaction. We describe the changes in flame structure that take place with increasing values of the flame temperature. We encounter first a 'merged' flame regime, for which the chemical reactions are confined to a thin zone, on the hot side of the flame, and the quasi-steady state approximation, applicable at lower flame temperatures can no longer be used. Then, we reach a slow recombination regime for which the radical is proposed in a thin zone and diffuses out to recombine in the outer transport zones. New effects, due to the radical diffusivity on the flame dynamics, are found in this regime.