THE STRUCTURE OF VARIABLE PROPERTY, COMPRESSIBLE MIXING LAYERS IN BINARY GAS-MIXTURES

We present the results of a study of the structure of a parallel compr essible mixing layer in a binary mixture of gases. The gases included in this study are hydrogen (H-2), helium (He), nitrogen (N-2), oxygen (O-2), neon (Ne) and argon (Ar). Profiles of the variation of the Lewi s and Prandtl numbers across the mixing layer for all 30 combinations of gases are given. It is shown that the Lewis number can vary by as m uch as a factor of 8 and the Prandtl number by a factor of 2 across th e mixing layer. Thus assuming constant values for the Lewis and Prandt l numbers of a binary gas mixture in the shear layer, as is done in ma ny theoretical studies, is a poor approximation. We also present profi les of the velocity, mass fraction, temperature and density for repres entative binary gas mixtures at zero and supersonic Mach numbers. We s how that the shape of these profiles is strongly dependent on which ga ses are in the mixture as well as on whether the denser gas is in the fast stream or the slow stream. (C) 1996 American Institute of Physics .