Nonequilibrium Vibrational Kinetics in the Boundary Layer of Re-Entering Bodies

Nonequilibrium vibrational distributions of N2 in the boundary layer surrounding a blunt body in hypersonic flow have been calculated by coupling the nonequilibrium vibrational kinetics, the dissociation and recombination processes, and the boundary-layer equations. The role of different energy exchange processes [vibration-vibration (V-V), vibration-translation (V-T), and recombination-dissociation] in affecting vibrational kinetics has been studied by considering each process. Then the complete kinetics are taken into account, obtaining a global view of the interplay of the different microscopic processes. The model used for the recombination/dissociation processes is such to selectively pump levels v = 25 and 45 of the N2 vibrational manifold. This vibrational energy is then redistributed by V-V and V-T processes. As a result, strongly nonequilibrium vibrational distributions are obtained, despite the thermalizing action of the V-T processes by nitrogen atoms.