Experiments in Numerical Studies of Low Density and Real Gas Effects on Regions of Shock Wave/Boundary Layer Interaction in Hypervelocity Flows

Experiments with extensive numerical simulations were conducted examining effects of low density flows and real gas effects on aerothermal characteristics of flows in hypervelocity facilities and in simple and complex flowfields in hypervelocity flows. These studies demonstrated that in the absence of real gas effects the DSMC and Navier-Stokes solutions accounting for slip effects were in excellent agreement with measurements. An extensive series of calibration and validation studies were done defining the free stream flows in the LENS I and X tunnels for low density and high enthalpy flows at velocities up to 16,000 ft/s. Measurements on double cone configuration showed that above 13,000 ft/s the interaction regions differed significantly in nitrogen and air flows; while the computations agreed with the measurements in nitrogen, they differed significantly in the size and properties of interaction regions in air. With the shuttle configuration, we demonstrated that real gas effects decrease the size of a separated interaction region over the flap, reduce the pressure over the adjacent curved surfaces, and reduce Reynolds number for onset of boundary layer transition.