Wake Effects and Synergies in Aeroelastic Wind Power Harvesting Systems

摘要

The study presented in this paper investigates the effects of the wake of a novel, low-power aeroelastic wind energy harvester on the power harnessed by a second harvester downstream of it, and serves as a preliminary study towards understanding the scalability of individual harvesters into a multi-unit array. Each harvester consists of a flexible cantilevered beam coupled with a wing that is free to rotate about a hinge at the beam's tip. Kinetic energy is harnessed from the wind in the form of aeroelastic flutter oscillations, an otherwise destructive force in the aeronautics world, and a pair of piezoelectric transducers on each harvester generates an alternating voltage from this kinetic energy. The two harvesters were tested in a wind tunnel, first individually and then in tandem for various streamwise and cross-stream separations between the two, and the power dissipated by their piezoelectric elements through a resistive load was measured. The results of the study show that substantial synergies are available for harnessing within a system of two harvesters, and that the power output of a second, trailing harvester can be increased by up to 27% of its original output due to the presence of a first, leading harvester oscillating at a particular location upstream of it. Furthermore, the results also indicate that even when no substantial synergistic effects between the two harvesters arise, only a minimal decrease (up to 6.5%) sometimes occurs in the power output of a harvester operating in the wake of another, making these devices highly suitable to scaling up into arrays of multi-unit systems.