Visualization of an Overdriven Detonation Phenomenon in a High Explosive

When a high explosive is initiated by a hypervelocity impact, an overdriven detonation process may be generated in the explosive. In this situation, the detonation front propagates faster than that at a Chapman-Jouguet (C-J) detonation. Some researchers have obtained the overdriven detonation with a velocity at about twice the C-J detonation velocity value. Based on this detonation velocity, the detonation pressure should be estimated to be around four times the C-J pressure. Employing the expansion of the detonation products at such a high-pressure state to propel the metal plate or to collapse the tube results in a much higher flying speed of the plate or tube than the action of the detonation products from the C-J detonation. Undoubtedly, it is an attractive technique for generating highpressure and high velocity for various researches and applications. This article presents an initial investigation of the overdriven detonation phenomenon by high-speed camera observation. The overdriven detonation is induced from the impact of the high-velocity metal plate. The results from the visualization experiment indicate that the apparent detonation velocities are higher than the C-J value but their magnitudes decrease with increasing propagation distance. The visualization experiment provides us with a qualitative, as well as a quantitative understanding of the overdriven detonation phenomenon.