Frequency-tunable airflow energy harvester using variable aperture helmholtz resonator and piezoelectric cantilever

This paper reports the design, fabrication and testing of a novel airflow energy harvester using variable aperture Helmholtz resonator with piezoelectric cantilever. Air flows through the resonator and vibrates the cantilever inside to produce power. At 15m/s airflow velocity, the 0.8~11mm variable aperture achieves 76~328Hz resonant frequency range. The harvester achieves maximally 1.6V peak-to-peak voltage at 6mm optimal aperture diameter, 15m/s air flow speed, corresponding to 221Hz resonant frequency. Peak-to-peak voltage changes as the airflow velocity changes. An active tuning circuit is presented to adjust aperture diameter to optimal value, thus improving output voltage at varying airflow velocity.