Experimental Investigations of Hypersonic Flow over Highly Blunted Cones with Aerospikes

TLDR

The study experimentally evaluates aerospike/aerodisk assemblies as retractable drag‑reduction devices for large‑angle blunt cones at hypersonic Mach numbers in the HST2 shock tunnel. Drag was measured with an internally mounted accelerometer balance, heat‑transfer rates were recorded to locate shock reattachment, and shock structure was visualized using electric discharge on a 120‑deg apex‑angle blunt cone with a 12‑mm flat‑tipped aerospike. The flat‑disk spike reduced drag by ~55% at zero angle of attack (Mach 5.75), heat‑transfer rates varied ±20% in the separated region indicating unsteady flow, and the measured drag and shock structure matched axisymmetric numerical simulations.

Abstract

Effectiveness of aerospikes/aerodisk assemblies as retractable drag-reduction devices for large-angle blunt cones flying at hypersonic Mach numbers is investigated experimentally in hypersonic shock tunnel HST2 using a 120-deg apex-angle blunt cone. An internally mounted accelerometer balance system has been used for measuring the aerodynamic drag on the blunt cone with and without forward-facing aerospikes at various angles of attack. The measurements indicate around 55% reduction in drag for the blunt cone with flat-disk spike at zero degree angle of attack for a freestream Mach number of 5.75. Surface convective heat-transfer rate measurements have been carried out on the blunt cone with a flat-disk tipped spike of varying length in order to locate the shock reattachment point on the blunt-cone surface. The measured heat-transfer rates fluctuate by about ±20% in the separated flow region as well as near the reattachment point indicating the unsteady flowfleld around the spiked blunt cone. The shock structure around the 120-deg apex-angle blunt cone with a 12-mm-long flat-tipped aerospike has also been visualized using the electric discharge technique. The visualized shock structure and the measured drag on the blunt cone with aerospikes agree well with the axisymmetric numerical simulations