Transition within a Hypervelocity Boundary Layer on a 5-degree Half-Angle Cone in Freestream Air/CO2 Mixtures

The most significant instability mechanism which leads to laminar to turbulent transition in hypervelocity flow over cold, slender bodies, characteristic of high enthalpy facilities like the T5 hypervelocity shock tunnel at Caltech, is the so-called second or Mack mode, which depends upon the amplication of acoustic disturbances trapped in the boundary layer, as described by Mack (1984). At high Mach number (4) and for cold walls, the first (viscous) mode is damped and higher inviscid modes are amplified, so that the second mode would be expected to be the only mechanism of linear instability leading to transition for a slender cone at zero angle of attack. The original document contains color images. Presented at the American Institute of Aeronautics and Astronautics (AIAA) Aerospace Sciences Meeting held in Dallas, TX on 7-10 January 2013.