Optimum operating techniques of two-state hypersonic gun tunnel

An operating technique of a two-stage hypersonic gun tunnel is presented. The two-stage gun tunnel differs from a conventional gun tunnel in that a free-piston compressor is used as a high-pressure source. Although the free-piston technique has previously been applied successfully to ballistic ranges, shock tubes, and shock tunnels, it has been difficult to adapt it to operate a gun tunnel. In this paper, an optimum operating condition of the two-stage gun tunnel is obtained by matching the gun tunnel diaphragm rupture with the position of the heavy piston in the compressor. It is concluded that the stagnation pressure and temperature become higher by 60% and 10%, respectively, than those of a conventional gun tunnel.