Free Piston Shock Tunnels: A Survey

This report is an extension to an earlier study conducted at NAL concerning the development of a free piston shock tunnel. It has been demonstrated in the literature that Free Piston Shock Tunnels (FPST) can generate large stagnation, enthalpies of the order of 45 MJ/Kg [HEG] required for simulating realistic reentry aerodynamics. The report begins with a brief discussion on hypersonic flow regimes, simulation methodology and shortcomings of the conventional hypersonic testing facilities. The evolution of free piston tunnel from basic shock tube is presented in detail. An attempt is made to summarise the salient features and performance parameters of the existing and the new facilities planned elsewhere in the world. Some of the important operational problems associated with the existing facilities are also discussed