LAMINAR SEPARATION IN SUPERSONIC FLOW.
Final rept., 1 Nov 62-30 Sep 63,
CENTRE NATIONAL D'ETUDES ET DE RECHERCHES AERONAUTIQUES BRUSSELS (BELGIUM)
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A study of three-dimensional flow perturbations in laminar supersonic flows was made on flat plates with sweptback leading edges and in the reattachment region of the flow over flat plates with backward-facing steps. It was shown that a cross-flow existed in the boundary layer on flat plates with supersonic sweptback leading edges of small bluntness, which increased in magnitude from the centerline towards the sides of the models. In separated flows, only an extremely small amount of cross-flow was needed to destabilize the flow and to create regular spanwise variations in total pressure. Larger cross-flows, controlled by a systematic variation of the angle of sweep either of the leading edge or of the edge of the step, had no further effect. Detailed surveys made in a reattaching laminar supersonic flow with a static probe showed that the three-dimensional perturbations that existed in the boundary layer were formed by two layers of equidistant contra-rotating streamwise vortices one located near the wall and a second one near the outer edge of the boundary layer. Author