Generation of the localized disturbances by the vibrating surface

Artikel i vetenskaplig tidskrift, 2000

Appearance and development of disturbances generated by 3-D vibrating surface in Blasius boundary layer are studied experimentally. The experiments were conducted under the controlled conditions where the preservation of phase information made it possible to obtain profound and accurate data, qualitative as well as quantitative, on the object under study. Surface vibration was provided by the loudspeaker working in the blowing-suction regime. Detailed hot-wire measurements showed that in case when the surface produces oscillations of low frequency and small amplitude, the packet of disturbances with the characteristics of Tollmien - Schlichting (TS) waves is observed downstream. When the effective amplitude is increased two times "blowing" leads to the appearance of the new type of disturbances: "puff"-structures, which have other characteristics of development in the boundary layer than Tollmien - Schlichting waves.