Numerical Investigations of Stability and Transition for a Blunt Swept Flat Plate at Mach 10

Numerical investigations were carried out to investigate the linear and nonlinear stability regime with respect to second-mode and crossflow instabilities for a blunt flat infinite swept plate at Mach 10. The infinite swept plate model has a leading edge radius of 5mm and a sweep angle of 75^∘. Linear Stability Theory (LST) identified multiple instability modes, including second-mode waves, traveling crossflow modes, and steady crossflow modes. The linear instability with respect to steady crossflow modes was further analyzed using Navier-Stokes calculations with controlled low-amplitude disturbance input to ensure linear development. These calculations identified the dominant steady crossflow mode with the highest growth rate. Nonlinear saturation of this mode was then investigated by increasing the forcing amplitude, forming the basis for secondary instability investigations. Secondary instability was examined by introducing a low-amplitude wave packet via short-duration pulse forcing in the presence of the saturated steady crossflow mode.