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Abstract

The performance of a diaphragm shock tube with an imploding detonation driver is theoretically and experimentally investigated. Strong shock waves are produced by a driver in which a detonation is forced to implode to the apex of a conical channel. In this geometry, the area convergence experienced by the imploding front elevates the driver gas temperature and pressure above the usual Chapman-Jouguet values, thereby increasing the strength of the test shock. Theoretically, the relationship between test shock strength, filling pressure, and area reduction in a conical channel is studied. Experimentally, the importance of the geometric parameters - slant angle, channel width and channel convergence - is investigated. The performance of the conical implosion driver compares well with that of other membrane shock tubes. For instance, for oxy-acetylene detonations, driving into argon of 5 Torr, a Mach number greater than 13 may be reached for a driver to test gas pressure ratio of 100. The same Mach number available from a Chapman-Jouguet detonation driver occurs only above a pressure ratio of 200. For cold hydrogen and constant volume oxy-hydrogen combustion, pressure ratios of 10⁶ and 2 X 10⁴ respectively are required to produce Mach 13. Design criteria for a large area reduction driving facility are also given.