The paper addresses the problem of searching for methods that can control, suppress, and attenuate explosive and detonation processes in homogeneous and heterogeneous media (mixtures of reactive gases and inert species). The analysis is performed by analytical and numerical methods. The problem of detonation suppression in a mixture of reactive gases and inert species (argon and sand particles) in a one-dimensional unsteady flow is formulated, and its solution is given. The effect of the particle diameter and concentration on the detonation velocity is determined; the parameters of the detonation wave in a stoichiometric hydrogen-oxygen mixture diluted by a chemically inert gas (argon) and particles is determined. The influence of the initial parameters of the mixture on the possibility of detonation suppression by inert particles is studied. It is shown that the detonation velocity substantially decreases with increasing volume fraction of particles. A decrease in the particle size with an unchanged volume fraction is also found to reduce the detonation velocity.

Three models of chemical kinetics of hydrogen combustion in oxygen and three gasdynamic models of the flow of a reacting mixture behind the front of an initiating shock wave are analyzed. The computed data are compared with experimental results in terms of the ignition delay versus temperature. It is demonstrated that the choice of the criterion determining the ignition delay for comparisons with experimental data is of major importance. A numerical analysis of three kinetic schemes of hydrogen ignition shows that a scheme with 38 reactions of 8 species offers the best description of experimental data in the range of temperatures from 1000 to 2800 K.

No abstract

The dynamics of particles of the disperse phase in a turbulent gas flow in planar shock waves sliding along a solid surface with a trapezoid cavity is examined numerically. Lifting of particles from the cavity walls is calculated in the approximation of a rarefied gas suspension. It is shown that the intensity of the transient shock wave and the initial positions of particles have a significant effect on the particle-lifting properties. The height of particle lifting is found to nonmonotonically depend on the initial streamwise coordinate and shock-wave Mach number. It is shown that zones of aggregation and subtraction of particles may be formed at the cavity bottom.Introduction. The problem of formation of a gas suspension under shock-wave forcing of a layer of a disperse material has been considered in many papers (see [1][2][3][4][5][6][7]). Some activities in this field were reviewed in [1]. The model of single particles used in [2] to describe lifting of particles of a rarefied dusty layer behind a transient shock wave (SW) takes into account the Saffman force and aerodynamic interference of the particle and the substrate in equations of motion of the particle. Using this model made it possible to obtain a qualitative description of the initial stage of lifting of particles ranging from 1 to 250 µm by transient shock waves of low and moderate intensity (the SW Mach number was M SW = 1.1-2.7), based on an analytically prescribed flow field of the gas phase in the approximation of an incompressible boundary layer. It seems of interest to perform computations without the restricting assumption made in [2] on setting the law of motion of the carrier phase in analytical form and to study the problem within the framework of the single-particle mode, with the flow field being computed on the basis of the k-ω model of turbulence.Formulation of the Problem. We consider the motion of a planar shock wave along a solid surface with a trapezoid cavity. There are particles of a disperse material on the cavity walls (and, possibly, inside the cavity as well). A sketch of the flow and flow-region geometry are shown in Fig. 1. At the initial time, the SW is on the left of the cavity at a certain distance from the point A; it propagates from left to right over a quiescent medium and reaches the cavity at a certain time. The flow arising in the vicinity of the cavity can induce separation of particles from the surface and their motion in the flow field of the gas. Let us consider the characteristics of this process by numerical methods of mathematical modeling.Mathematical Model. Gas Phase. To describe the motion of the carrier phase, we used the Favre-averaged full Navier-Stokes equations written in a generalized curvilinear coordinate system η = η(x, y), ξ = ξ(x, y) [8]: