An experimental study of a vortex/mixing-layer interaction

Abstract

The first phase of a subsonic experimental investigation of the structure of a longitudinal vortex and the effect of the vortex on a two-stream turbulent mixing layer has been completed. A stable and well-defined longitudinal vortex was generated by mounting a half-delta-wing vortex generator in the wind-tunnel settling chamber. A detailed flow-visualization study, using the smoke-laser technique, was conducted, and X-wire probes were used to measure the mean-flow and turbulence quantities. At the upstream locations, the vortex was found to develop some normal stresses within the core region. The vortex also induced strong secondary motions and small increases in the normal stresses within the mixing layer. The normal stresses then combined with the appropriate mean-velocity gradients to generate shear stresses farther downstream. The results indicate that more sophisticated turbulence models will have to be developed if such complex interactions are to be computed accurately.