Boundary-Layer Transition Experiments in a Hypersonic Quiet Wind Tunnel

Abstract

This paper reports the progress of three projects in the Boeing/AFOSR Mach-6 quiet tunnel at Purdue University. The first project used a 7-deg half-angle cone at 6-deg angleof-attack with temperature-sensitive paint applied to the frustum and small roughness dots added near the nosetip. Depending on the spacing of the roughness, the spacing and breakdown of the stationary vortices was altered. The second project looked at modifications to a pulsed jet perturber to reduce the perturbation duration. This was accomplished through both electronic and physical modifications to the perturber system. Shorter duration perturbations were achieved, but further progress is required. The third project measured low-frequency disturbances in the first-mode instability frequency range with Kulite pressure transducers on the surface of a cone-ogive-cylinder model. Initial measurements show that the magnitude of the low-frequency disturbance on the cone-ogive-cylinder is greatest outside the boundary layer, which may indicate an entropy-layer instability.