Megahertz visualization of compression-corner shock structures

The interactions between shock waves and turbulent boundary layers in a Mac h 2.5 wind tunnel have been visualized by a megahertz-rate imaging system. The shock waves were produced by two-dimensional compression corners having angles of 14 and 24 deg, and the Hows were, respectively, attached and sep arated. At the compression corner, the sequential images clearly indicate t he correlation between the shock motion and the incoming turbulent boundary layer. Some large eddies in the boundary layer cause the shock to move in the streamwise direction for distances as large as the boundary-layer thick ness at a frequency as high as large-eddy frequency (U-e/delta), but other eddies seem to have minor effect on the shock wave. The images also indicat e how the shock waves influence the boundary-layer structures.