Measurement of Three-Components of Force on an Airframe Integrated Scramjet at Mach 10

Abstract

Force balance experiments have been conducted within The University of Queensland’s T4 Stalker Tunnel with a small airframe-integrated three-dimensional scramjet engine using a three-component stress wave force balance. The tests were conducted at conditions replicating flight at Mach 10 and a dynamic pressure of 52 kPa or 28 kPa. The internal flowpath featured a rectangular-to-elliptical shape transition (REST) inlet, an elliptical combustor with a constant area and a diverging section, and a three-dimensional thrust nozzle. This flowpath was integrated with a forebody and streamlined external geometry to provide the test model. Gaseous hydrogen fuel was injected either through portholes on the inlet, from a series of portholes behind the rearward facing step at the combustor entrance, or a combination of the two. The fuel-off drag coefficient was measured to be 0.246 ± 0.025 and 0.312 ± 0.032 at the high and low dynamic pressure test conditions respectively. At a fuel equivalence ratio of 1.20, the drag coefficient reduced to 0.118 ± 0.034 for a combined injection scheme at the high dynamic pressure test condition, corresponding to a specific impulse increment of 2160 s and a specific thrust increment of 740Ns/kg. This work represents the first time that force data have been measured for a hydrogen fuelled REST scramjet engine at true-flight Mach 10 test conditions.