Structure and stability of a laminar diffusion flame in a compressible,three-dimensional mixing layer

In this paper we consider the structure and stability of a three-dimensional, finite rate, reacting compressible mixing layer lying between two streams of reactants with different freestream speeds and temperatures. Using both numerical calculations and asymptotic analyses, the structure of the ignition and diffusion flame regimes was studied; in particular the effect of crossflow on the structure. The results of both approaches are in good agreement. In the stability analysis the general case of three-dimensional disturbances was studied. It was shown that certain general results, in particular the circle theorem, could be easily extended to three-dimensional disturbances in a compressible fluid with crossflow. The introduction of a chemical reaction, in the form of a flame sheet, was found to have complex effects on flow stability. These included the appearance of additional neutral modes compared with the nonreacting case and substantial changes in growth rates with heat release, the skew angle of the mean flow, and the direction of propagation of the disturbance wave. These results are discussed in detail.The first author was supported, in part, by AFOSR Contract 91-0180, and in part by the National Aeronautics and Space Administration under NASA Contract No. NASI-19480 while in residence at the Institute for Computer Applications in Science and Engineering, NASA Langley Research Center, Hampton, VA 23681-0001, U.S.A. The second author was supported, in part, by AFOSR Contract 91-0250, and in part by the National Aeronautics and Space Administration under NASA Contract No. NASI-19480 while in residence at the Institute for Computer Applications in Science and Engineering, NASA Langley Research Center, Hampton, VA 23681-0001, U.S.A.