Flutter suppression of an airfoil using a nonlinear energy sink combined with a piezoelectric energy harvester

Abstract

We propose an absorber combined with a nonlinear energy sink and piezoelectric energy harvester (NES-PEH) for suppressing the flutter of a two-degree-of-freedom (2-DOF) airfoil. The NES-PEH is a cascade device comprising of a magnetic nonlinear energy sink (NES) and a tuned piezoelectric beam for broadening the vibration absorption frequency band. It is installed inside a 2-DOF airfoil, supported by four spring cantilever beams and a spring steel wire, for suppressing the flutter response and harvesting mechanical energy. A flutter model of the airfoil connected to the NES-PEH is established using unsteady aerodynamic theory. The influence of the dimensionless parameters of the NES-PEH on the flutter response and output voltage is explored. Furthermore, experiments are designed and tested for verifying the effectiveness of airfoil flutter suppression by the NES-PEH. The results indicate a significant influence of the installation position of the NES-PEH on the flutter response. The NES-PEH installed behind an elastic axis can increase the flutter speed by 20.4%, whereas that installed in front of the elastic axis can effectively suppress the pitch amplitude of the limit cycle oscillation (LCO) by 24.2%. Moreover, at d = −35 mm, the NES-PEH exhibits the best performance compared with the nonlinear energy sink and its fixed counterpart, suppresses flutter and the LCO, and outputs 10 μW power. Overall, this study presents a novel method for suppressing flutter and harvesting energy simultaneously.