Suction Flow Control at High Reynolds Number

Flow control has been shown to reduce the aero-optic distortion due to density ∞uctuations within a wake of an airborne turret. By manipulating the ∞ow over the turret directly afiects the density ∞uctuation that incur aero-optic distortions. This paper focuses on suction ∞ow control over a three-dimensional turret at a freestream velocity of Mach 0.3. Aero-optic measurement were taken over the ∞at aperture of the turret with and without open loop suction control clearly showed a decrease in the distortions as the amount of suction increased. Fluctuating surface pressure simultaneously sampled with the aero-optic measurements showed the inverse where as the suction increased the surface pressure rms decreased. Another set of tests were taken as the hemisphere dynamically pitching with open-loop and closed-loop suction ∞ow control. The closed-loop control system employed a low dimensional measurement based proportional controller. Both the open-loop and closed loop control test showed a change in ∞ow over the aperture as compared to the baseline case.