Hypersonic boundary layer transition control over a 3$^{\circ}$ half-angle sharp cone via distributed porosity

The effectiveness of ultrasonic absorptive coatings (UACs) in achieving delay in turbulent transition on a hypersonic boundary layer over a 3 $^\circ$ half-angle cone was investigated under flight-like free-stream disturbance conditions. Tests were conducted at the Boeing/AFOSR Mach 6 Quiet Tunnel at Purdue University for four free-stream Reynolds numbers ranging from $9.0\times 10^6\,$ to $14.3 \times 10^6\,\rm m^{-1}$ . Silicon-carbide-coated carbon foams with pore densities of 60, 100 and 200