FLAME PROPAGATION WITH A SEQUENTIAL REACTION-MECHANISM

The steady propagation of a flame through a premixed combustible mixture is studied for the case in which the flame is characterized by the production and depletion of a significant intermediate species. The overall chemical reaction mechanism is of the sequential type. The method of matched asymptotic expansions is used to derive a solution for large activation energies, in which case both chemical reactions are confined to a thin layer. The (small) separation distance H between the points where the two reactions go to completion and the propagation velocity U play the role of eigenvalues and are determined as functions of standard flame parameters. The formula for H also represents the effective spatial distance between production and depletion of the intermediate species and is thus a measure of the flame thickness.