Detonation Initiation via Imploding Shock Waves

An imploding annular shock wave driven by a jet of air was used to initiate detonations inside a 76 mm diameter tube. The tube was filled with a test gas composed of either stoichiometric ethylene-oxygen or propane-oxygen diluted with nitrogen. The strength of the imploding shock wave and the sensitivity of the test gas were varied in an effort to find the minimum shock strength required for detonation of each test mixture. The results show that the minimum required shock strength increases with mixture sensitivity and suggest that impractically large shock driver pressures are required to initiate detonations in ethylene-air or propane-air mixtures when using this technique.