Study of Base Pressure in Laminar Hypersonic Flow: Re-entry Flight Measurements

Abstract

Base pressure data from flight tests of four full-scale re-entry vehicles are analyzed. The flight vehicles were nearly identical, slightly blunted, 9° half-angle sphere cones. Flow conditions were hypersonic, M^ * 16-20, and the cone boundary layer and near wake were laminar for Reynolds numbers Re L between 2 X10 and 5 x 1C. The flight data are compared with available theory and groundand flight-test data for similar configurations. Various correlation parameters, derived from both experimental ground-test and theoretical results, are utilized in this analysis. Suitable data correlations, were obtained with the reduced Reynolds number suggested by Wu and Su and with parameters from the Reeves and Buss theory. Correlations of the present data are directed toward establishing a basis for re-entry vehicle preflight predictions and postflight data analyses. Resulting base pressure calculations for other slender configurations (7°, 8°, and 10° cones) in hypersonic entry conditions show good agreement with both theory and flight data and indicate the importance of including real-gas and nose-bluntness effects in high Reynolds-number laminar flows.