Analytical and experimental investigation of a turbulent mixing layer of different gases in a pressure gradient

Abstract

An analytical and experimental study was made of the turbulent mixing layer in adverse and zero pressure radients. Theory predicts the possible existence of equilibrium flows, and this was confirmed experimentally for turbulent shear layers between streams of helium and nitrogen. The only case for which similarity is possible is described. The experimental investigation was conducted in a facility designed to produce turbulent flows at pressures up to 10 atmospheres. Adjustable walls of the test section of the apparatus were modified in order to set the pressure gradient. Shadowgraphs of the mixing zone for both types of gradient at different Reynolds numbers revealed a large scale structure noticeably different for each. The similarity properties of the shear layer were established from mean profiles of total head and density.