Realization of Super-orbital Entry Flow using Expansion Tube

Expansion tube has a theoretical potential to realize a ultra-high-enthalpy flow for simulating acrothermodynamics of super-orbital entry flights capsule. However, since test gas stagnates at the secondary diaphragm for rupturing diaphragm, an ideal test gas is not obtained. The influence of the secondary diaphragm conditions on the test gas flow in expansion tube was examined through the shadowgraph image of framing interval ljs and the pressure measurement. By using adequately-thin diaphragm, e.g. Mylar sheet of 3im-thickness, as the secondary diaphragm, the rupture process got close to the ideal and the reflection shock wave could be reduced. Test gas flow of shock speed of about 7.5 km/s was maintained for 30Os for the pressure of gas in the shock tube = 3.5kPa and that of acceleration tube = 16Pa.