Experimental investigations of the boundary layer receptivity, on the sharp leading edge of a flat plate, to acoustic waves induced by two-dimensional and threedimensional perturbers, have been performed for a free-stream Mach number M ∞ = 5.92. The fields of controlled free-stream disturbances were studied. It was shown that two-dimensional and three-dimensional perturbers radiate acoustic waves and that these perturbers present a set of harmonic motionless sources and moving sources with constant amplitude. The disturbances excited in the boundary layer were measured. It was found that acoustic waves impinging on the leading edge generate Tollmien-Schlichting waves in the boundary layer. The receptivity coefficients were obtained for several radiation conditions and intensities. It was shown that there is a dependence of receptivity coefficients on the wave inclination angles.

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A localized heating or cooling effect on stability of the boundary-layer flow on a sharp cone at zero angle of attack and freestream Mach number 6 is analyzed. Experiments were carried out in the Transit-M wind tunnel of the Institute of Theoretical and Applied Mechanics (Novosibirsk, Russia) for different heating/cooling intensities and freestream Reynolds numbers. The mean flows with localized heating/cooling are calculated using axisymmetric Navier-Stokes equations. These solutions are used for the spatial linear stability analysis to estimate the transition onset points using the e N method. Direct numerical simulations of two-dimensional disturbances propagating in the boundary layer through the cooled/heated region are performed. The experiment and computations showed similar qualitative trends. The localized cooling decreases the second-mode amplitude and delays transition. The heating produced an opposite effect, which is less pronounced.