Active Control and Optical Diagnostics of the Flow over a Hemispherical Turret

The effects of flow control actuation on the aerodynamic characteristics and aero optical distortions in the near wake of a hemispherical turret model were investigated in a series of wind tunnel experiments at M = 0.3 – 0.64. Flow control was applied using a spanwise array of high-frequency synthetic jet actuators oriented such that the long sides of their rectangular orifices were aligned in the streamwise direction. The effects of actuation on the flow dynamics and aero-optical distortions were characterized using Malley probe measurements, along with distributions of static surface pressure and hot-wire anemometry. One of the main findings of the present work was that the dissipative, small-scale motions that are induced by the actuation (StD > 1) resulted in suppression of turbulent fluctuations within the separated flow over the hemisphere, and concomitantly in significant reduction in the levels of optical distortion (in excess of 40% at M = 0.4). The effect of the momentum limited actuation diminishes at M > 0.45.