A Preliminary Experimental Investigation of the Flow over Simple Bodies of Revolution at M=18.4 in Helium

Abstract

An experimental investigation was conducted in the GALCIT hypersonic blow-down tunnel to determine surface pressure distributions and shock wave shapes for a series of "sharp"-nosed and slightly-blunted bodies of revolution at a nominal Mach number of 18.4 and a free stream Reynolds number of 6.20 x 10^5 per inch. The four bodies investigated were as follows: (1) 15° half-angle "sharp" cone; (2) 15° half-angle spherically-blunt cone (bluntness ratio= .24); (3) 20° half-angle "sharp" cone; (4) 2/3-power body. The pressure distributions on the "sharp" cones agreed well with the Taylor-Maccoll theory. As expected, the pressure near the nose of the blunt cone was much higher than predicted by this theory, but the pressure decreases monotonically to a value lower than the theoretical value on the conical skirt, indicating that the flow has over-expanded. The measured shock wave shape for the 2/3-power body was found to be proportional to x^(0.69), and the shock wave ordinates agree closely with those predicted by Cole and by Kubota and Lees. Measured surface pressure distributions on the 2/3-power body are predicted satisfactorily by the Kubota-Lees analysis. A simple correction for boundary layer growth accounts for most of the increase in pressure on the rear portion of the body over the values predicted by inviscid theory.