Propagation of cellular detonation in a gas suspension in the presence of a concentration gradient

Abstract

Models for the description of detonation flows in inhomogeneous gas particle mixtures are presented. The physical and mathematical model of heterogeneous detonation of aluminum suspensions is based on approaches to the mechanics of heterogeneous media and semi-empirical laws of ignition and combustion of particles. The model is extended for suspensions that are inhomogeneous in particle concentrations. This suggests the solution of an additional equation for the spatial distribution of initial concentrations. The dependence of the integral heat release of chemical reactions and the fraction of unburned particles on the initial composition is determined from the solution of the stationary problem of the structure of the detonation wave and its agreement with empirical data on the rate of normal detonation. The model for describing detonation in mixtures of reacting gases with inert particles is based on an analysis of the state of chemical equilibrium. The problem of the initiation and development of cellular detonation in a flat channel in the presence of a longitudinal or transverse gradient of the concentration of aluminium particles is considered. The limits of changes in concentrations from poor to super stoichiometric compositions are considered for 1 μm particles. When detonation propagates along a channel with a longitudinal positive (negative) concentration gradient, the cellular structures do not change, but the average and peak values of pressure and phase density increase (decrease). With a transverse concentration gradient, cell-like structures with a curved front, asymmetric and strongly elongated cells form in the channel. The results are consistent with studies of similar gas detonation flows.