Transition Delay in Hypervelocity Boundary Layers By Means of CO2/Acoustic Instability Interaction.

摘要

The potential for hypervelocity boundary layer stabilization was investigated using the concept of damping Mack's second mode disturbances by vibrational relaxation of carbon dioxide (CO2) within the boundary layer. Experiments were carried out in the Caltech T5 hypervelocity shock tunnel and the Caltech Mach 4 Ludwieg tube. The tests used 5-degree half-angle cones (at zero angle of attack) equipped near the front of the cone with an injector consisting of either discrete holes or a porous section. Gaseous CO2, argon (Ar) and air were injected into the boundary layer and the effect on boundary layer stability was evaluated by optical visualization, heat flux measurements and numerical simulation.