LAUSR

Abstract Regimes of detonation propagation in channels with linear expansion filled with monodisperse mixtures of oxygen and ultrafine aluminum particles of various loading are studied by methods of numerical simulations. The detonation combustion of submicron aluminium particles is described within the semi-empirical model taking into account transition from diffusion regime to kinetic one. As the initial conditions, waves of both planar and cellular detonation were considered. The characteristics of the main flow regimes were obtained and described: subcritical (detonation failure), critical (detonation failure in some part of the channel) and supercritical (continuous detonation propagation). Maps of flow regimes were constructed for particles of 200 nm and 400 nm in the plane of parameters: channel width, expansion angle. The obtained critical conditions are closing to those observed in gas detonation. The expansion angle linearly depends on the critical channel width to a first critical value, after a second critical value the expansion angle is independent of the channel width. At that, there is a certain region of nonmonotonicity similar to the detonation of micro-sized suspensions of aluminum particles. The effect of particle loading on critical conditions shows itself in poor mixtures in the form of a sharp increase in the critical channel width with a decrease in the mass concentration below 0.25.