To Nonlinear Disturbance Interactions in 3D Supersonic Boundary-Layer

Experimental data on the nonlinear wave train development in 3D supersonic boundary layer over a 45 degrees sweptwing at Mach number 2 are presented. Travelling artificial disturbances were introduced in the boundary layer by periodical glow discharge at frequencies 10 and 20 kHz. It is shown that the additional peaks in beta'-spectra arise for both subharmonic and fundamental frequencies. The experiments indicate the presence of oblique breakdown mechanism in 3D supersonic boundary layer. The three-wave triad consisting of two primary travelling waves and one steady wave is discussed. The linear stability theory results demonstrate the possibility of the existence for such triads.