Experimental study of a compressible countercurrent turbulent shear layer

Abstract

A countercurrent shear layer with a nominal convective Mach number (M c ) of 2 is generated using a unique arrangement. The shear layer growth rates were found to be twice that of conventional, coflowing shear layers at comparable M c . It is hypothesized that the countercurrent shear layer becomes self-excited, leading to a modification of the turbulent properties. Instantaneous flow visualization images clearly reveal the presence of large, highly convoluted, turbulent structures believed to be responsible for the enhanced growth rates. The flowfield was also examined for the presence of eddy shocklets that have been observed in numerical simulations under similar compressible flow conditions. Even though the countercurrent flowfield appears to satisfy the criteria for the creation of shocklets, a careful and thorough search revealed no evidence of their presence.