Experimental study of flows in a two-dimensional inlet model

Abstract

Experimental results are reported for flows in a ramp-type, external-compression inlet with a rectangular, large-aspect-ratio cross section, at a freestream Mach number of 1.84. Variation of the exit throttle area created a wide range of operating conditions, from highly supercritical to fully subsonic internal flows with a detached shock ahead of the ramp lip. Both time-mean and dynamic aspects of the flows were investigated. At high terminal-shock Mach numbers (1.5-2.2), three different, massively separated, subsonic flow patterns were found, which depended on throttle setting and the history of prior flow conditions. A specific pressure ratio could be associated with at least two such patterns. At low pressure ratios, the terminal shock was weak and strongly influenced by the ramp/cowl configuration. The presence of leading edges is believed to have been closely involved in the large-amplitude, periodic oscillations (buzz) observed at the low end of the pressure-ratio range.