High speed imaging of flow establishment and durationin impulse facilities

摘要

The flow establishment processes and the duration of the test time in low and high enthalpy impulse facilities have been investigated by using high speed flow imaging and time-resolved surface sensors. For the low enthalpy facility, the high speed imaging gave sufficient information to fully characterise the steady flow time including a measurement of the flow Mach number. Results for tests on a higher speed super-orbital expansion tube showed that imaging of the shock stand-off on a blunt body gives a good indication of the duration of the flow establishment processes. However, static pressure measurements provide a better indication of the end of the test time defined by the arrival of the leading edge of the unsteady expansion generated by diaphragm rupture.