NONEQUILIBRIUM WAKES WITH LAMINAR AND TURBULENT TRANSPORT

Abstract : The problem of the wake of a reentry vehicle is briefly reviewed, and an analysis is formulated for the solution of the nonsimilar, nonequilibrium viscous flow equations with laminar and turbulent transport. The air is treated as a mixture of eight components (N2, N, O2, O, NO, NO+, e-, and O2(-) in which the vibrational and electronic excitation modes are assumed in equilibrium with the translational mode. For the calculation of the rate of formation of each species, the reaction rates based on the most recent measurements are employed. Numerical results are presented for the wake of a 15-foot, 8-degree (half-angle) cone at 22,000 ft/sec, for altitudes of 150,000 feet and 115,000 feet. Based on the results of a recent correlation of wake transition data, instantaneous transition from laminar to turbulent flow is assumed to occur 250 feet from the cone vertex at 150,000 feet altitude, and 50 feet from the vertex at 115,000 feet altitude. The nonequilibrium effects are found to be appreciable at both altitudes particularly with respect to electron concentration. In the region where the temperature drops below 800K, the effect of three-body molecular attachment is found to be predominant. (Author)