Fundamental aspects of the coupling of non-equilibrium vibrational kinetics and dissociation-recombination processes with the boundary layer fluidynamics in N2 and air hypersonic flows

A ladder climbing model including V-V (vibration-vibration), V-T (vibration-translation) energy exchange processes linked to a dissociation recombination kinetics has been developed and inserted in the fluid dynamics equations describing the boundary layer surrounding a non-catalitic surface hitted by an hypersonic flow of atomic and vibrationally excited molecular nitrogen. The results show a strong overpopulation of vibrational levels with respect to Boltzmann distributions along the coordinate perpendicular to the surface and a corresponding non-Arrhenius behaviour of dissociation constants. The extension of the model to the air system confirm the strong non-equilibrium character of the relevant kinetics even though the reaction between vibrationally excited nitrogen and atomic oxygen controls both N2 dissociation and NO formation