Numerical Simulation of the Growth of Localized Disturbances in a Supersonic Boundary Layer over a Plate with Longitudinal Slots

This paper presents the results of numerical simulations of the growth of small amplitude localized disturbances in the boundary layer on a flat plate and on a plate with rectangular longitudinal slots at Mach number 2. The simulations were performed with the FlowVision software under flow conditions corresponding to those in the T-325 wind tunnel of the Khristianovich Institute of Theoretical and Applied Mechanics SB RAS. Cases with slots no deeper than the boundary layer thickness were considered. The localized disturbances in the boundary layer were generated by a time-pulsed, spatially localized heat supply from the plate surface. For a smooth plate, the growth of the disturbances was compared with the results of the linear stability theory. Data agreement was achieved for the grid resolution used. For the cases of the smooth surface and the plate with longitudinal slots, the evolution of disturbances in the boundary layer was analyzed in physical and wave space. In case of the smooth plate, the disturbance introduced into the boundary layer increases monotonically downstream. However, in the presence of longitudinal slots, the growth of the disturbance growth is different and depends on the depth of the slots. It has been shown that longitudinal slots can affect the stability of the supersonic boundary layer. A frequency-wavenumber analysis of the disturbance evolution revealed that longitudinal slots shift the range of the most unstable waves towards a region of higher frequencies compared to the smooth plate. This effect becomes more pronounced with increasing depth of the slots.