Heat Transfer and Pressure Distribution on Sharp and Finite Bluntness Biconic and Hemispherical Geometries at Various Angles of Attack in a Mach 15–20 Flow

Abstract

Heat transfer and pressure measurements and schlieren flow visualization photographs have been made on five vehicle nose shapes tested in the V.K.I. Longshot free piston wind tunnel at flow Mach numbers of 15 and 20. The models tested were two hemisphere configurations with a smooth and a chemically etched rough surface, and three 50°–8° half-angle biconic configurations with sharp- and blunt-nosed smooth surfaced versions and a sharp-nosed version with a heavily machined roughness. Comparisons have been made of the measurements of heat transfer rate with currently used engineering predictions of heat transfer rate. Measured pressure distributions and shock shapes agreed well with proven inviscid theories. The boundary layer measurements on the smooth models at M=20 conformed to laminar behavior. Model surface roughness appeared to promote turbulent flow. The shock-wave on the 50° half-angle cone at 10° incidence remained unexpectedly attached to the nose even though subsonic flow was formed on the windward side.

This research has been sponsored in part by the Air Force Materials Laboratory through the European Office of Aerospace Research, OAR, United States Air Force, under Contract No. F61052-70-C-0031.