Chemical energy release in self-sustaining detonation waves in condensed explosives

Abstract

The nonequilibrium Zel'dovich-von Neumann-Doring (ZND) model of a one-dimensional detonation wave is applied to condensed phase (solid and liquid) explosives in this paper. In condensed explosives, the detonation wave is assumed to consist of four main zones: a narrow leading shock wave; a much thicker induction zone in which the intra- and intermolecular vibrational degrees of freedom rapidly equilibrate and the rate-determining endothermic bond-breaking reaction then proceeds at a rate governed by the equilibrium von Neumann spike conditions; a narrow chemical reconstitution zone in which the unreacted explosive rapidly decomposes and recombines into highly vibrationally excited reaction products; and another thick relaxation zone in which the reaction products expand and approach thermal equilibrium at the Chapman-Jouguet (CJ) state. Gruneisen-type equations of state are used to calculate the energy release in several condensed explosives at various initial densities. Along with kinetic and chemical energy release, the release of potential or cold compression energy in the exothermic chemical reconstitution and vibrational deexcitation zones sustains the leading shock front. The conditions for amplification of transverse pressure waves in the zone of highly vibrationally excited reaction products are shown to exist for condensed explosives. The effects of the resulting complex cellular structure of detonation waves on the energy release in homogeneous (liquid) and heterogeneous (solid) explosives are qualitatively discussed.