EFFECTS OF SHEAR AND STRAIN ON TEMPORAL EVOLUTION OF LAMINAR DIFFUSION FLAMES

Closed-form analytical solutions that describe the evolution of diffus ion flames in two-dimensional laminar flowfields due to an initial lin e source of fuel in an infinite oxidizer environment are derived. The velocity field is assumed to be divergence free and both steady and un steady shear and plane stagnation flows are considered in this study. The flame surface is modeled as an infinitesimally thin flame sheet at which fuel and oxidizer are consumed at an infinitely fast rate; thus , chemical kinetic effects are ignored. Validity of the solutions are discussed. The flame shapes are observed to be elliptic. The flame fro nt moves away from the source at early times; whereas at later times, the front collapses at the location of the fuel source. An expression for the time for complete consumption of the fuel is derived in each c ase, and it is shown that strain fields are more conducive to combusti on.