Repetitively Pulsed Hypersonic Flow Apparatus for Diagnostic Development

A repetitively pulsed hypersonic test facility has been constructed and characterized. This apparatus was designed to enable advanced laser diagnostic development. The underlying principle is to synchronize the intermittent tunnel operation with the laser pulses to achieve effectively continuous operation. Repetitively pulsed (2-20 ms pulse lengths) uniform supersonic flow at Mach 4.6 and hypersonic flow at Mach 6.2 were demonstrated for extended operation: The nozzle flows were characterized using fast-response pressure sensors and NO planar laser-induced fluorescence imaging for two-dimensional temperature and velocity measurements. The pulse-to-pulse impact pressure repeatability was within 1.0%, corresponding to exit How velocity and temperature fluctuations of 0.7 and 1.0%, respectively. The apparatus can operate over a unit Reynolds number range of 6.0 x 10(4) to 3.0 x 10(6) m(-1).