Detonation failure characterization of non-ideal explosives

Robert S Janesheski, Purdue University

Abstract

Current methods of characterizing non-ideal explosives require large-scale testing to obtain steady detonation wave propagation for analysis due to the relatively thick reaction zones. A small scale experiment would be very useful in quickly characterizing many materials. Use of a microwave interferometer applied to small-scale confined transient experiments was implemented yielding time resolved characterization of a failing detonation that is useful to models. The microwave interferometer was used to measure the position of a failing detonation wave in a confiner that was initiated with a booster charge. Experiments have been performed with ammonium nitrate and multiple fuel compositions (diesel fuel and mineral oil). It was observed that the failure dynamics were influenced by factors such as the chemical composition, confiner thickness, and initiating shock wave strength. Thin wall confiners with 0.71 mm wall thickness experienced detonation failure and decoupling of the shock wave from the reaction zone. Confiners with a wall thickness of 34.9 mm showed a decrease in detonation velocity as the detonation front advanced. Varying the shock strength (detonation pressure) showed proportional changes in the initial overdriven detonation velocity through the non-ideal explosives. The distance to complete detonation failure was also shown to be proportional to the initial shock strength. The high temporal resolution of the position of the detonation front produced with the microwave interferometer allows for the transient effects associated with the failure dynamics of the detonation to be combined within a single measurement. This experimental method is shown to be repeatable and can be performed with little required material (about 2 grams).

Degree

M.S.M.E.

Advisors

Son, Purdue University.

Subject Area

Mechanical engineering

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