Wall-cooling effects on secondary instabilities of Mack mode disturbances at Mach 6

In hypersonic boundary layers, Mack modes play a crucial role in flow instability, whose secondary instability is hot research topic. Since flight vehicles will probably work under high-stagnation temperature conditions, which significantly affect the aerodynamic heating calculation and aero-thermal protection design of vehicles, it necessary to compare primary instabilities layers that Boeing/AFOSR Mach 6 quiet tunnel (BAM6QT). Herein, wall-cooling adopted order not consider chemical reactions. With same freestream 100 K, two with wall 20 600 corresponding cooled condition wind condition, respectively, are chosen conduct linear/non-linear stability analysis. Our results show most dangerous mode originates from fast discrete present cooled-wall born slow BAM6QT layers. Furthermore, when amplitude disturbances large, fundamental resonance always dominates resulting steady streaky structures have largest spectrum. addition, point out distribution eigenfunctions subharmonic different various wall-temperatures. What more, ratios incoming changed spanwise wave-angle disturbances.