Characterisation and integration of piezoelectric trimorph actuators for blade active surface control on a scaled wind turbine

The paper investigates the integration of piezoelectric bending actuators on trailing edge flaps (TEF). The characterisation of piezoelectric actuators is of great importance due to differences in performance resulting from sample variability, actuator construction, circuit type and equipment. For the application of trailing edge flaps in scaled turbines, the total deflection these actuators can produce determines the possible flap angles and, consequently, the potential effects on wake evolution downwind of the wind turbine. In this paper, we fully characterise the performance of the piezoelectric bending actuator under a variety of operating conditions. The bridged bi-polar circuit is used to drive the piezoelectric actuators with both a static and a dynamic signal. Deflection results demonstrate that the piezoelectric actuator is capable of achieving flap angles of β ± 3° with a static signal, and β = 2.3° and β = −3.2° angles with a dynamic signal. Experimental force measurements using a dynamic signal result in a force reduction of up to 33% when compared to a static signal. Force values at increasing frequencies do not show a depreciation in force. Additionally, initial aerodynamic loads exerted on TEF are presented based on XFoil simulations to ensure that the piezoelectric actuating force can overcome aerodynamic loads for future experiments. Experimental force measurements from the piezoelectric actuator demonstrate that aerodynamic forces can be overcome. This work serves as the first step towards implementing the TEF technology in lab-scaled wind turbine models.