Nomenclature

Wind-tunnel testing of a hypersonic inlet with rectangular-to-elliptical shape transition has been conducted at Mach 4.0. These tests were performed to investigate the starting and back-pressure limits of this fixed-geometry inlet at conditions well below the Mach 5.7 design point. Results showed that the inlet required side spillage holes in order to self-start at Mach 4.0. Once started, the inlet generated a compression ratio of 12.6, captured almost 80 % of available air and withstood a back-pressure ratio of 30.3 relative to tunnel static pressure. The spillage penalty for self-starting was estimated to be 4 % of available air. These experimental results, along with previous experimental results at Mach 6.2 (Smart, M.K, “Experimental Testing of a Hypersonic Inlet with Rectangular-to-Elliptical Shape Transition”, Journal of Propulsion an