2-STREAM, SUPERSONIC, WAKE FLOWFIELD BEHIND A THICK BASE .1. GENERAL FEATURES

An experimental investigation of the complex interaction region generated by the separation of two supersonic streams past a finite-thickness base has been conducted in a two-dimensional wind tunnel. The data were obtained using schlieren photography, pressure measurements, and two-component laser Doppler velocimeter measurements. The shear-layer mixing regions are characterized by initially constant-pressure mixing, by an evolution of velocity profiles from truncated boundary-layer shapes to wakelike profiles farther downstream, and by relatively high levels of turbulence. The separated flow region is characterized by large reverse flow velocities and strong interactions with the low-velocity regions of both shear layers. Turbulence intensities and kinematic Reynolds stresses are strongly affected by the separation process at the base and increase greatly in the latter portions of the two shear layers and in the recompression region. Recovery of the mean velocity field in the redeveloping wake occurs quickly, while the turbulence field remains perturbed to the fastest streamwise location investigated.