A second-mode stability analysis has been performed for a hypersonic boundary layer on a wall covered by a porous coating with equally spaced cylindrical blind microholes. Massive reduction of the second mode amplication is found to be due to the disturbance energy absorption by the porous layer. This

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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.

A problem of evolution of the Rayleigh-Taylor instability on a sinusoidally perturbed interface in the field of artificial gravity is studied on the basis of the model of a three-velocity three-temperature mixture of gases. If the upper part of the mixture consists of the light and heavy gases (the heavy gas is heavier than the pure gas at the bottom, but the mixture as a whole is lighter than the pure gas), it is demonstrated that the growth of perturbations with formation of mixture jets penetrating into the pure gas is observed in a certain range of concentrations of the heavy gas.Key words: Rayleigh-Taylor instability, gas-dynamics of a three-velocity three-temperature mixture. Introduction.A mathematical model of a three-velocity three-temperature mixture of gases is proposed to study the evolution of the Rayleigh-Taylor instability at the interface of a mixture of two gases on one side and the third (pure) gas on the other side. The accelerated motion of the mixing layer separating two gases with different densities is accompanied by the development of instability, which arises if the presence of the light medium leads to acceleration of motion of the heavy medium or if the heavy medium is located above the light medium in the gravity field. This type of instability is called the Rayleigh-Taylor instability [1]. Traditionally, the mixing layer is considered as a surface of density discontinuity, i.e., as a contact discontinuity. The influence of the processes of mutual penetration of the gases was ignored in numerical simulations of the evolution of the Rayleigh-Taylor instability based on the Euler equations. Therefore, it seems of interest to study this problem on the basis of equations for a multi-velocity multi-temperature mixture of gases, where each species has its own velocity and temperature. Such an approach allows us to describe both the processes of mutual penetration of the gases and the evolution of the mixing layer arising on the interface. The results of research of the instability evolution on the interface in binary mixtures were described in detail in [2][3][4]. In the present paper, we describe the results of investigations of the development of the Rayleigh-Taylor instability arising on the interface of a three-species mixture of gases, where the mixture of the light and heavy gases is located above the less heavy gas in the field of artificial gravity. The density of the mixture located above the interface is smaller than the density of the gas below the interface. From the viewpoint of the classical gas dynamics, such a mixture is stable to comparatively small perturbations [1]. The emergence of convection in the gravity field was observed in such a mixture in experiments [5][6][7]. Obviously, this phenomenon cannot be adequately described within the framework of the one-velocity and even two-velocity approximation. It is necessary to use the equations of gas dynamics of a three-velocity threetemperature mixture.Formulation of the Problem. Let us consider the evolution of perturbations...

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