Closed-Loop Flow Control for an Articulating Turret

A series of wind tunnel tests were performed to evaluate systems for controlling the flow over a three-dimensional, articulating turret. The turret has two rotational degrees of freedom: pitch and yaw. The yaw angle is modulated sinusoidally in time at three fixed pitch angles, creating asymmetric (and fully turbulent) flow over the turret. Control actuation consists of suction jets located on the top of the turret, using the duty cycle of valves in the suction lines to change suction velocities. One valve controls suction velocity in jet slots located on the left side of the turret, and another valve controls velocity in jet slots on the right. Each valve is controlled by an independent, proportional regulator that receives signals from a separate measurement-based state estimator—utilizing two groups of surface pressure sensors located on the top of the turret (left and right). The multipleinput-multiple-output (MIMO) controller is twice as effective as an open-loop controller in reducing average levels of fluctuating velocity. The closed-loop system is also three times more efficient as measured by the ratio of control effectiveness to required input.