Closed-Loop Control of a Microtab-Based Load Control System

A closed-loop control system has been developed for microtabs and demonstrated in the University of California, Davis, Aeronautical Wind Tunnel. Input to the system comes from two dynamic pressure transducers located at 15% chord on the upper and lower surfaces of the airfoil. Microtabs with a height of1% chord are located at 95% chord on the lower surface and 90% chord on the upper surface, enabling rapid increase or decrease of the lift force through deployment of the tabs on the pressure or suction side of the airfoil, respectively. Tests have been conducted with variations of up to 23% in airspeed, and the control system is able to reduce the total deviation in the lift force by 60% compared to the performance of the airfoil without the control system. The experiment validates the effectiveness of closed-loop control of lift using a trailing-edge tab-based system for lifting surfaces such as wind-turbine rotor blades.