Active Control of Flow Separation and Structural Vibrations of Wind Turbine Blades


The feasibility of using synthetic jet actuators to enhance the performance of wind turbine blades was explored in wind tunnel experiments on a small scale model blade. Using this technique, the global flow field over the blade was altered such that flow separation was mitigated. Consequently, this resulted in a significant decrease in the vibration of the blade. Global flow measurements were conducted, where the moments and forces on the blade were measured using a six component wall-mounted load cell. The effect of the actuation was also examined on the surface static pressure at two spanwise locations; near the blade's root and near its tip. In addition, Particle Image Velocimetry (PIV) technique was used to quantify the flow field over the blade. Using synthetic jets, the flow over the blade was either fully or partially reattached, depending on the angle of attack, and the Reynolds number. Furthermore, the changes induced on the moments and forces, as well as on the blade vibrations were found to be proportionally controllable by either changing the momentum coefficient, the number of synthetic jets used, or by the driving waveform. Finally, a proof-of-concept closed-loop control system was developed to test the ability of using synthetic jet actuators to restore and maintain flow attachment and reduce the vibrations in the blade during dynamic pitching maneuvers. The control system demonstrated the ability of synthetic jet actuators to reduce blade vibrations during dynamic motion depending upon their control concept, which might be either pitch or active stall control.

Maldonado, V., Farnsworth, J., Gressick, W. and Amitay, M, "Active Control of Flow Separation and Structural Vibrations of Wind Turbine Blades."

Wind Energy, Volume 13, Issue 2-3, p. 221-237, March-April 2010.