Synergistic Wake Interactions in Aeroelastic Flutter Vibration Energy Harvester Arrays

Abstract

This research experimentally investigates the operation of several aeroelastic flutter energy harvesters in an array. In order for such a wind energy harvesting array to operate effectively, it is important to understand the interaction between neighboring power harvesters including downstream wake effects, and how these interactions can be leveraged to maximize the output of the system. The fluttering motion of the energy harvester imparts an unsteady wake into the flow downstream of the device. Wind tunnel experiments with a pair of flutter energy harvesters show that this wake structure has significant effects on the oscillation amplitude, frequency, and power output of the trailing device. These wake interaction effects are shown to vary with the stream-wise and cross-stream separation distance between the two devices. At some separations, an advantageous frequency lock-in between the two devices occurs. When this occurs, the wake of the leading device adds constructively with the trailing device, causing larger oscillation amplitudes and higher power output in the trailing device. Experiments to characterize this variation in power output due to these wake interaction effects and to determine the optimal spacing of the energy harvesters are presented and discussed.