Wind energy harvesting from a conventional turbine structure with an embedded vibro-impact dielectric elastomer generator

In this paper, a novel wind energy harvester is proposed and studied. The wind energy harvester consists of a conventional two-blade horizontal wind turbine and a vibro-impact (VI) dielectric elastomer generator (DEG) embedded symmetrically at the end of a rotating shaft. The wind energy is harvested by the VI DEG due to the rotational motion of the turbine's blades and the shaft. The dynamic model of the proposed system under wind-induced rotations is established theoretically, and the energy harvesting (EH) process of the VI DEG is introduced with the system output voltage and power being derived. The impact-based rotational energy harvesting process of the system is validated experimentally by measuring the output voltages of a single-sided impact (SSI) DEG under different impact velocities, and by measuring the ball's impact moments under rotational excitations, thus demonstrating the feasibility of the impact-based EH of DE material. Furthermore, the dynamical and electrical behaviors of the system under different wind speeds are fully studied through numerical simulations. The influences of the wind speed, tip speed ratio and the distance between dielectric elastomer membranes (DEMs) on the system EH performance are further discussed. It is found that the proposed wind energy harvester can work effectively in a range of small wind speed and produce a relatively high output power as large as 0.7125 mW under a wind speed of 3.99 ms−1. The tip speed ratio, distance between two DEMs can be selected as the adjusting parameter to produce optimal EH performance under different wind speeds, thus providing an effective solution for the design and improvement of the proposed system under different wind environments.