Investigation of Relaxation Processes in Flow about Models in Hypersonic WindTunnels of Different Types

摘要

This report presents the theoretical and experimental results related to flowsover such simple bodies as semisphere, cone, and wedge. These were investigated in hypersonic wind tunnels of various classes at nearly equal Mach and Reynolds numbers (M from 7.0 to 8.0, Re(o) from 135 to 240) but at notably different free-stream velocities: 790, 2700 and 6000 m/s. Hypersonic resistance and arc-heating wind tunnels and a hypersonic MHD-accelerator wind tunnel, as well as their test equipment are described. A technique to determine parameters of a free stream over a model including gasdynamic ones (M, Re, Re(o), T, P, V, Ho, H) and physico-chemical ones (gamma To, Tv, Tn, Ci), as well as a verification procedure are presented. Experimental data on pressure distribution over models, shock wave positions/shapes were obtained. The experimental data are compared with respective calculated results obtained by using the VSL theory and the Navier-Stokes equations for the test conditions adopted. Interrelation of the theoretical and test data is shown not to be unambiguous, especially in what concerns locations and shapes of shock waves. The VSL theory is employed to compute local parameters of the shock layer. The influence of alkali metal seed on the rate of relaxation in the shock-layer is considered. Features of profiles of both temperature and air component concentrations in the shock layer are shown to be useful in explaining a set of phenomena revealed in experiments: a radiation offset upstream of a sphere hypervelocity shock layer, a radiation relaxation at a cone apex. The impact of the seed metal is shown to be insignificant.