DNS of Compressible Inert and Infinitely Fast Reacting Mixing Layers

Abstract

This paper deals with the effects of heat release and compressibility on temporally evolving, turbulent mixing layers. Direct Numerical Simulations (DNS) of such layers at two different convective Mach numbers are performed with and without combustion which allows to study the effects of heat release and compressibility separately and combined. It is shown that both, compressibility and heat release, dampen the turbulence activity and lead to a reduced growth of the mixing layer. Alterations in pressure fluctuations are a main reason for the changes. The effects of compressibility are not as strong in the reacting mixing layer as in the inert one. A significant difference between the inert and the reacting mixing layers at high convective Mach number is that entropic density fluctuations prevail over the acoustic ones when reaction takes place while both contribute to nearly equal parts in the non-reacting compressible flow.