Active flow control of a turbulent boundary layer with large-window and stereo-PIV

The large coherent structures present in the boundary layer play an important role in the self-sustaining mechanisms in wall-bounded flows. This work focuses on the manipulation of a turbulent boundary layer, in particular of these large scale structures using synthetic jet actuation. The current experiment implements an array of two synthetic jet actuators oriented in the spanwise direction, located approximately 2.7 meters downstream from the leading edge of a flat plate (Re_T ≈ 1200). Actuation is applied perpendicular to the surface of the flat plate with varying blowing ratios and reduced frequencies, in an open-loop sense, to manipulate the length and time scales associated with turbulent boundary layer. Large field of view and stereoscopic particle image velocimetry (PIV) are performed in a complementary fashion at the University of Southampton and the University of Toronto Institute for Aerospace Studies (UTIAS), respectively. Presented in this paper are the effects of the blowing ratio and reduced frequency of the actuation system on the overall flow field. PIV measurements are also compared between the two sets of experiments.