Chemical energy release in the cellular structure of gaseous detonation waves

Abstract

The nonequilibrium Zel'dovich-von Neumann-Doring (ZND) model is applied to the three-dimensional cellular structure of ordinary and marginal gaseous detonation waves. Calculations of the nonequilibrium chemical energy release in the chain-propagating reactions of H 2 + Cl 2 at various shock temperatures show that relatively thick zones of highly vibrationally excited reaction products exist at varying distances behind all of the shock fronts in the cellular structure. Therefore, each of these shock fronts is supported to a different extent by the chemical reconstitution process. Calculations for ordinary detonations of H 2 + Cl 2 and 2H 2 + O 2 using a constant transverse wave strength and a simple rigid wall reflection for the transverse wave collision process yield good agreement with experimental cell parameters. The calculations indicate that approximately 1 4 of the energy required for self-sustaining propagation of the leading shock front is furnished by the transverse wave collision process. For a marginal detonation in 2H 2 + O 2 + 3Ar, calculations based on a decreasing transverse wave strength and the recent suggestion of Dormal et al. that the reinitiation process at the end of a cell includes a detonation in the precompressed explosive behind the incident wave agree with experimental measurements. This application of the nonequilibrium ZND model may explain the experimental observation of a cellular structure in an overdriven detonation whose heat of reaction is endothermic and suggest extensions of the Vasil'ev et al. model of a cell in a self-sustaining gaseous detonation wave.