Experimental investigation and dynamic analysis of a novel electromagnetic energy harvester based on airfoil flutter

In addition to high output, high environmental adaptability and the ability to withstand complex aerodynamic conditions are crucial for vibration energy harvesting. This paper introduces a novel sliding electromagnetic energy harvester based on airfoil flutter (EEHAF). The EEHAF features a simple and reliable structure, where the sliding motion and linear spring design enable it to operate under large amplitudes, thereby enhancing its environmental adaptability. It can optimize output power through adjustable magnet arrangements while minimizing effects on flutter characteristics. Wind tunnel experiments demonstrated that, with four magnets per groove, the root mean square output voltage increased from 0.23 V to 0.52 V, enhancing output power by a factor of 4.89 at 9.3 m/s. To investigate observed phenomena, including stick–slip behavior and changes in flutter amplitude along with wind speed, a theoretical model is developed using the Lagrange equations, incorporating friction and nonlinear aerodynamic forces. Simulations reveal that friction-induced stick–slip behavior adversely affects energy harvesting by prolonging the stick phase. Additionally, as the wind speed increases, the plunge amplitude initially rises, then stabilizes, and decreases due to aerodynamic drag moments at high angles of attack. The model also shows that a high static friction coefficient significantly increases the cut-in wind speed. The EEHAF offers significant potential for optimization and application, providing new possibilities for the development of energy harvesting technology in aeroelastic field.