An Experimental Investigation of the Flow over Blunt-Nosed Cones at a Mach Number of 5.8

Abstract

Shock shapes were observed and static pressures were measured on spherically-blunted cones at a nominal Mach number of 5.8 over a range of Reynolds numbers per inch from 97,000 to 238,000, for angles of yaw from 0° to 8°. Six combinations of the bluntness ratios 0.4, 0.8, and l.064 with the cone half angles 10°, 20°, and 40° were used in determining the significant parameters governing pressure distribution. The pressure distribution on the spherical nose for both yawed and unyawed bodies is predicted quite accurately by the modified Newtonian theory given by C_p = C_(P_(max)) cos ^2 η, where η is the angle between the normal to a surface element and the flow direction ahead of the bow shock. Cone half angle was found to be the significant parameter in determining the pressure distribution near the nose-cone junction and over the conical afterbody. On the 40° spherical nosed cone models the flow overexpanded with respect to the Taylor-Maccoll pressure in the region of the spherical-conical juncture, after which the pressure returned rapidly to the Taylor-Maccoll value. For models with smaller cone angles the region of minimum pressure occurred farther back on the conical portion of the model, and the Taylor-Maccoll pressure was approached more gradually. The shape of the pressure distributions as described in nondimensional coordinates was independent of the radius of the spherical nose and of the Reynolds number over the range of Reynolds number per inch between .97 x 10^5 and 2.38 x 10^5. Integrated results for the pressure foredrag of the models at zero yaw compared very closely with the predictions of the modified Newtonian approximation, except for models with large cone angles and small nose radii, where the drag approaches the value given by the Taylor-Maccoll theory for sharp cones.

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