The investigation of a fluid piston shock tunnel concept for the production of hypersonic flows

A theoretical investigation of a hypersonic facility concept called the "fluid piston shock tunnel" has been performed. The analysis utilizes an advanced quasi-one-dimensional computational code developed as part of the research. The details of the formulation are presented. Attributes of the formulation include high pressure, high temperature thermodynamics, area change, friction effects, and radiative heat transfer. The computational model discretely tracks shock and contact surface discontinuities and their interactions. The developed software represents an advancement over current shock-capturing quasi-one-dimensional formulations. The fluid piston shock tunnel concept utilizes a cold reservoir upstream of the driver section of a conventional shock tunnel. The reservoir delays the reflected expansion from primary diaphragm rupture which produces a steadier test environment and allows the use of air as a driver section gas thus eliminating molecular contamination issues. The effect of reservoir geometry, the nozzle starting process, and the effect of friction and radiation on performance are presented. The fluid piston shock tunnel concept produces 2.5 to 4.5 km/s flows with test times of at least 40ms with nozzle exit diameters of at least 1.5m. This performance represents an order-of-magnitude increase in test time over current shock tunnel facilities that will meet the future ground testing needs of emerging hypersonic systems.