Experimental Investigation of Hypersonic Buzz on a Delta Configuration

Abstract

N experimental study is described which confirms the existence of hypersonic buzz in the separated region of a downward deflected control surface. Wind-tunnel tests in helium at M = 17.5 clearly demonstrated the occurrence of large-scale pressure oscillations throughout a substantial range of angles of attack and control surface deflections on a blunt slab, delta configuration. Measurements of surface pressure fluctuations and observations of high-speed schlieren photographs served to delineate the boundaries of the phenomenon and to identify the physical parameters necessary for the onset of a buzz condition. Prominent spectral energy peaks in surface pressures were observed and correlated with the instability. These conditions were found to be strongly dependent on the presence of multiple shock interactions relative to the location of a reattaching shear layer.