Experimental investigation of the supersonic flow past a slender cone at high incidence

Abstract

The supersonic flow field past a circular cone of semi-apex angle 7·5° at incidences up to 26° has been investigated experimentally at a free-stream Mach number of 2·94. The experiments were made using a five-hole conical-head directional probe. Since the flow past the cone was found to be conical, the flow phenomena may be described in a plane perpendicular to the cone axis. This paper gives the direction of the conical streamlines, the conical sonic line and the conical Mach number in such a plane, all of which may be deduced from the measurements. At incidences exceeding twice the cone semi-apex angle a separated flow regime was observed which consisted of two main vortices on either side of the leeward plane of symmetry, and probably also two secondary vortices close to the cone surface. From incidences of 17° onwards, an embedded region of conical supersonic flow terminated by a shock wave was revealed. At 22°, approximately, a second embedded shock wave was measured close to the cone surface and extended slightly across the leeward plane of symmetry. This shock wave may have been generated by the vortex system, which induced supersonic cross-flow components towards the cone.

Comment on 'Critique of turbulence models for shock-induced flow separation'

“…The results of the computations show that, due to the additional ground effect generated by the secondary vortex, the pressure spike splits into two. Similarly, the ground effect of a vortex causing low pressure can also explain the flowfield features observed in flows about delta wings, 6 in flows over a cone at high angles of attack, 7 and in flows over sharp and blunt fins. 8 I agree with Ericsson that turbulence models for shockinduced flow separation are very important.…”

“…Hung's colleague, Horstman, found that his Navier-Stokes calculations could detect a secondary seapration in the case of a highly swept sharp fin, provided the grid was, refined enough. 7 However, the secondary yortex structure was of insignificant size and could not explain the upstream influence observed experimentally, and "the reasons for this discrepancy remain a mystery." In his plans to solve this mystery through improving the computational method, Horstman does not discuss, any efforts to improve the prediction of the primary vortex structure, which Hung thought "was probably not corz«7.62 cm …”

Computation of the inviscid supersonic flow about cones at large angles of attack by a floating discontinuity approach

“…The nature of the vortical singularity for cones at large angles of attack has been investigated in several theoretical (5,(20)(21)(22) and some recent numerical (23,24) studies. Experimental evidence (25)(26)(27)(28) indi…”