STRUCTURE AND STABILITY OF A LAMINAR DIFFUSION FLAME IN A COMPRESSIBLE, 3-DIMENSIONAL MIXING LAYER

In this paper we consider the structure and stability of a three-dimen sional, finite rate, reacting compressible mixing layer lying between two streams of reactants with different freestream speeds and temperat ures. Using both numerical calculations and asymptotic analyses, the s tructure of the ignition and diffusion flame regimes was studied; in p articular the effect of crossflow on the structure. The results of bot h approaches are in good agreement. In the stability analysis the gene ral case of three-dimensional disturbances was studied. It was shown t hat certain general results, in particular the circle theorem, could b e 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 stabi lity. These included the appearance of additional neutral modes compar ed with the nonreacting case and substantial changes in growth rates w ith heat release, the skew angle of the mean flow, and the direction o f propagation of the disturbance wave. These results are discussed in detail.