Performance analysis of a harmonica-type aeroelastic micropower generator

This article investigates the influence of the design parameters on the performance of an aeroelastic micropower generator with the goal of minimizing its cut-in wind speed and maximizing its output power. The generator, which mimics the basic physics of music-playing harmonicas, transforms wind energy into electricity via the self-excited oscillations of a piezoelectric reed embedded within a cavity. Previously, the authors have presented and validated an analytical aeroelectromechanical model describing the response behavior of the generator. By utilizing the proposed model, this study implements a stability analysis and numerical optimization algorithms to delineate the influence of the design parameters on the device's response. The effect of the electric load, chamber volume, and aperture size on the cut-in wind speed is investigated. The results illustrate that the cut-in wind speed can be reduced significantly if the device is designed with an optimal chamber volume, which is shown to be inversely proportional to the square of the beam's first modal frequency. Minimizing the aperture width is also shown to significantly reduce the cut-in speed. However, due to the reduced strain rate in the piezoelectric layer, it is observed that minimizing the wind speed does not always yield an increase in the output power. As such, a numerical investigation of the influence of the design parameters on the output power is utilized to generate design charts that assist in the selection of the optimal parameters for a known average wind speed. Several qualitative verifications of the theoretical trends are also presented through an experimental case study.