Studies of the Effects of Transitional and Turbulent Boundary Layers on the Aerodynamic Performance of Hypersonic Re-Entry Vehicles in High Reynolds Number Flows.

摘要

This report describes a series of studies to investigate the underlying aero-thermodynamic phenomena which influence the accuracy and survivability of Ballistic Reentry Vehicles. The influence of transition on the aerodynamic characteristics of slender RV's is discussed first. Here the primary interest was in determining the influence of the angle of attack and bluntness ratio on the shape of the transition front and the properties of these regions. A detailed study was made of the influence of asymmetric nose bluntness on the pressure and heat transfer distribution over the cone frustum, and the contribution of the cone frustum to the forces and moments experienced by the total configuration. Particular emphasis was placed on determining the destabilizing effect of the NRV and RTE nose shapes recovered from flight tests. It was found that nose shaping can significantly change the pressure distribution over the conical frustum relative to a spherically-capped configuration; this effect must be accounted for if accurate predictions of cone stability at low altitude are required. Detailed heat transfer and pressure measurements made on a model of the NRV nose shape for test conditions indicated that regions of flow separation and shock wave boundary-layer interaction were induced over this configuration and produced heating rates in the reattachment regions on the ablated conical frustum of up to three times those recorded at the stagnation point on the spherical nose tip.