Gas-dynamic instabilities in a non-equilibrium chemically active medium

A dispersion equation is obtained that describes the dynamics of acoustic and entropy modes in a nonequilibrium chemically active gas, taking into account viscosity, thermal conductivity and arbitrary dependences of the vibrational relaxation time, specific heating and cooling power on density and temperature. The linear dynamics of acoustic instability in a nonequilibrium chemically active gas has been studied. An analysis of the influence of chemical reaction parameters on the acoustic increment and phase speed of sound was carried out. Areas with anomalous values of the phase speed of sound and acoustic increment, which fall into the zone of forbidden sound frequencies, are analyzed. The linear dynamics of thermal instability in a nonequilibrium chemically active gas has been studied. An analysis of the influence of chemical reaction parameters on the instability increment and the phase velocity of entropy modes was carried out. Threshold values for the degree of non-equilibrium of the environment have been determined, above which thermal instability may develop. A mathematical model of the dynamics of linear disturbances in a nonequilibrium chemically active medium with a non-uniform distribution of flow parameters along one of the spatial coordinates has been constructed. Dispersion equations are obtained that describe the linear dynamics of the Kelvin-Helmholtz instability, unstable symmetric and antisymmetric modes in nonequilibrium chemically activesupersonic jets. The influence of vibrational relaxation and chemical activity in a nonequilibrium gas on the stability of a tangential velocity discontinuity has been studied. It is shown that taking into account vibrational relaxation and chemical activity in a nonequilibrium gas leads to a significant increase in both the Kelvin- Helmholtz instability for all flow modes (subsonic and supersonic) and unstable symmetric and antisymmetric jet modes. The stability of the interface between two quiescent chemically active media, differing in the degree of nonequilibrium, has been studied. It is shown that for typical values of the parameters of nonequilibrium vibrationally excited chemically active media, the imaginary part of the frequency turns out to be positive, i.e. the interface is unstable.