EXPERIMENTAL STUDIES OF HYPERSONIC SHOCK-INDUCED BOUNDARY-LAYER SEPARATION

Previous experimental investigations of shock/boundary layer interacti ons on a flat plate at free stream Mach numbers between 6 and 8.7 reve aled longitudinal counter-rotating vortices downstream of the interact ion region. In subsequent studies the influence of nose radius of blun ted plates and of wall curvature on the formation of the vortices was investigated. The experiments were carried out in the hypersonic blow down facility of DLR Cologne. The diagnostics included surface oil flo w visualization, infrared thermography, Pitot pressure measurements an d Schlieren optics. First numerical results obtained by other authors working in the same research program showed persuasive agreement with the experimentally observed vortex structures, in particular with resp ect to their diameter and the number of vortex pairs. In comparison th e experimental Schlieren images were also reproduced with good accurac y by the numerically simulated images, obtained from computed density distributions. The numerical now predictions verified a second flow re circulation inside the separation region, the existence of which had t o be postulated by the experimental results.