Asymptotic Analysis of Laminar Flame Propagation with Variable Transport Coefficients

This paper reports an extended formula for the burning velocity of a steady one-dimensional, planar, adiabatic flame in the case of a one-step irreversible decomposition reaction. As a generalization of previous analyses, which were concerned with constant-property flames, variable transport coefficients and variable mean molecular weight are taken into account. The resulting effects on the burning velocity are discussed and explained on physical grounds. A distinguished downstream zone involving a convective-reactive-diffusive balance is discovered to exist for all reaction orders greater than unity and to influence the burning rate if the Lewis number differs from unity, more strongly than the variable-property effects for reaction orders of three or greater.