The X3R Free-Piston Reflected Shock Tunnel: Australia's New Large-Scale, Long-Duration Hypersonic Testing Capability

X3R is a new, large-scale free-piston driven reflected shock tunnel designed and operated at the University of Queensland, Australia. The facility is a derivative of the X3 super-orbital expansion tube, which uses a combination of new and pre-existing hardware. It is capable of generating 600 mm diameter Mach 7 test flows at 25 kPa and 50 kPa dynamic pressure for durations of approximately 12.5 ms. Previously, hypersonic testing in Australia was limited in both scale and duration, due to the size of the local facilities capable of experimentation in this regime. This paper presents the new facility and summarizes its current operational capabilities. This includes a description of the facility geometry, and details of the two currently available operating conditions. These conditions were specifically designed to overcome the drawbacks of the tunnel’s relatively short free-piston driver, and use a high helium fraction driver gas to produce a long duration but low compression ratio driver response