Based on the results of numerical simulation of a nonstationary, nonaxisymmetric turbulent swirling gas flow in a tube with local sources of heat release, it is shown that a precessing vortex core (PVC) appears at supercritical values of the swirl parameter as a result of the development of instability of a left-handed bending mode. The dependence of the PVC frequency on the mass flow rate of the gas and the heat-source power has been studied. As the heat-source power increases, the frequency of precession grows while the amplitude of vortex core oscillations drops.

The method of matched asymptotic expansions is used to analyze the evolution of disturbances of a nonequilibrium compressible boundary layer on a flat plate in the region of nonlinear critical layer. A dispersion relation is obtained for low-amplitude subsonic disturbances. An equation is derived, which describes the evolution of disturbance in the nonlinear stage of its development. It is demonstrated that, similar to the case of equilibrium media, the increase in the disturbance amplitude in the given stage of development of turbulence exhibits an explosive pattern. The characteristic time of instability decreases with increasing degree of disequilibrium of the medium.

The stability of vortical disturbances propagating at an angle to the main flow in a nonequilibrium compressible supersonic boundary layer has been investigated. The dependences of the critical Reynolds number on the degree of nonequilibrium and on the Mach number were defined at different angles of wave propagation. It was calculated the time of explosive instability, which realized on stage of nonlinear critical layer. The increment of secondary instability versus degree of non‐equilibrium S and amplitude of primary equilibrium solution was founded.

Nonlinear equations are derived, which describe the evolution of two-dimensional acoustic disturbances in a thermodynamically nonequilibrium gas. The characteristic features of parametric interaction of wave packets in acoustically active media are analyzed. The transmission band under conditions of critical and noncritical matching and the threshold of parametric amplification are determined. Conditions are obtained, under which a giant parametric pulse may form in an acoustically active medium, with the amplitude of this pulse exceeding that of a pumping wave.

Without Abstract

The evolution of weak shock waves in nonequilibrium gas media with fluctuating parameters is investigated. Two-dimensional nonlinear, evolution equations are derived for the averaged parameters of an acoustic field induced by a body in a supersonic flow of active medium. A possible mechanism of reduction of the amplitude and broadening of the front of weak shock waves in nonequilibrium gas media is discussed.

A mechanism responsible for a decrease in the turbulent friction of bodies moving in (or streamlined by) a vibrationally-nonequilibrium gas flow is proposed. Heating of the gas in the immediate vicinity of the surface as a result of heterogeneous relaxation may decrease the transverse velocity gradient and reduce the friction resistance coefficient.

The classical problem of a supersonic flow past a slender body is generalized to the case of non-equilibrium gas. Under homogeneous conditions, expressions for resistance and lift coefficients are derived. It is shown that a reduction of these coefficients is possible in nonequilibrium gas. Nonlinear models are obtained, which make it possible to determine the structure of the acoustic field emitted by a body.

The stability of plane acoustically active gas flows is investigated. It is shown that, in a nonequilibrium gas flow, the interaction of acoustic waves with two-dimensional eddy disturbances, when accompanied by the decay of the former, leads to considerable qualitative changes in the stability properties of the latter. In an inhomogeneous nonequilibrium gas flow, the eddy disturbances may become unstable at Reynolds numbers below the critical one and may increase with the acoustic increment at the expense of the parametric pumping of energy from the unstable acoustic modes.

The classical problem of the fluid mechanics is the problem of a supersonic motion around a thin body was generalized to the case of non-equilibrium gas. The drag and lift force coefficients were founded. It is shown that the drag and lift force coefficients in the acoustically active supersonic flow are both decreased.

The mechanisms for the evolution of microwave discharges in high-pressure inert gases are analyzed. The time behavior of the densities of various particles in the plasma layer and of the electrodynamic characteristics of the discharge are studied numerically. It is shown that the dynamics of the discharge originate in the development of an instability associated with stepwise ionization.

It’s considered some effects of the gas‐plasma interaction that is discharge damping behind the shock wave front, the structure of the weak shock wave (SW) front in plasma and SW generation by the breakdown wave front.

The development of a breakdown wave in subthreshold HF fields is considered for the condition that the field energy density exceed the plasma energy density E2/4π > nT. It is shown that the breakdown wave propagation mechanism is controlled by HF diffusion with a coefficient μiE2/4πen. A model of breakdown development along the direction of the linear field polarization is constructed on the basis of this mechanism.