AUTHORS: S. A. Gaponov, A. N. Semenov, A. A. Yatskikh

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ABSTRACT: For the first time the development of localized disturbances of a small intensity in a supersonic boundary layer for Mach number M=2 was investigated numerically. Propagation speeds of localized disturbances are estimated. It was established that the speed of the forward front is more than the speed of the back front. Maximum mass flux disturbances were observed at ymax where ρU(y)/(ρU)∞≈0.6—0.8, that will be coordinated with experimental data. In the field of the forward front oscillations are arising in process of the wave packet movement down a stream, and its amplitude grows on time. For comparison of results of numerical modeling to the classical stability theory the wave package at ymax were expanded in a spectrum on frequencies and wave numbers. The maximum contribution to the total perturbation to belong to waves with inclination angles of a wave vector to the leading edge of the plate equal to forty degrees. The spatial amplification rates of oblique wave are in the good correspondence with data of the stability theory of locally nonparallel flows

KEYWORDS: - Supersonic flow, boundary layer, hydrodynamic stability, laminar-turbulent transition, localized disturbances

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