SPATIAL NONHOMOGENEITY EFFECTS IN NONEQUILIBRIUM VIBRATIONAL KINETICS

The paper addresses several problems of kinetics of spatially nonhomog eneous, vibrationally excited gas flows. It is shown that vibrational energy transfer in most diatomic molecules does not affect the transpo rt coefficients of a gas, despite very fast vibration-to-vibration (V- V) rates among high vibrational levels. The influence of diffusion and the vibration-to-electronic (V-E) energy transfer on the vibrational distribution function (VDF) and on the vibrational energy balance is d iscussed. The diffusion and V-E corrections to the VDF and to the gas heating rate in vibrational relaxation is obtained for the ''strong'' excitation regime. The effect of the non-local diagnostics on the VDF is considered. It is shown that the spatial integration may significan tly influence the inferred distribution function, as has been previous ly reported in experiments. A new approach for kinetic modeling of non homogeneous, vibrationally nonequilibrium flows is suggested. A two-di mensional kinetic model is developed which combines vibrational and tr anslational energy balance and gas motion equations with the analytica l theory of anharmonic oscillators. The comparison of the model calcul ations with both 1D and 2D experiments shows reasonable agreement with in the applicability of the gas flow model.