Generation of perturbations by a localized vibrator in the boundary layer of a nonswept wing

Origination and development of perturbations generated by a three-dimensional vibrating surface in the boundary layer on an airfoil with a zero slip angle is experimentally studied. Surface vibrations were generated by a Mylar membrane. It is shown that high-amplitude vibrations of a three-dimensional surface lead to simultaneous formation of two types of perturbations in the boundary layer: quasi-stationary streamwise structures and wave packets accompanying them. The presence of regions with favorable and adverse pressure gradients does not exert a significant effect on evolution of streamwise structures but leads first to attenuation and then to amplification of wave packets.