Analysis and numerical simulation of a nonpremixed flame in a corner

A new model problem in which fuel and oxidizer enter the reaction zone in m utually perpendicular directions is formulated in order to understand the p rocess of flame-positional stability. In the present paper, an analytical f ormulation valid at the limit of constant density and infinitely fast chemi stry is used to obtain solutions in the convective and diffusive limits. A full numerical simulation in which the compressible reacting flow equations are solved for one-step, finite-rate chemistry is utilized to examine the effects of stoichiometry, reactant velocities, and preheating on laminar fl ame location and structure. The effect of increased fuel velocities and red uced stoichiometric mixture fraction is to bring the flame zone closer to t he oxidizer surface, consistent with the simplified analytical predictions and previously reported experimental observations. This corner flame has so me of the characteristics of both a classical premixed and a diffusion flam e. Under certain conditions, it has the structure of an edge flame. Numeric al simulations of a simplified form of the thermodiffusive equations, with the same kinetic scheme yield similar overall results. However, there are q ualitative and quantitative differences, which are attributed to simplifica tions employed. (C) 1999 by The Combustion Institute.