A study on the acoustic energy harvesting with Helmholtz resonator and piezoelectric cantilevers

Abstract

Some kinds of thermofluid instruments are using Helmholtz resonators for absorbing noises radiated from them. Since the resonance frequency of a Helmholtz resonator depends on the ratio of the resonant volume to the neck size, operating frequency range can be easily tuned and thus the Helmholtz resonator is well-suited for noise control in a wide range of frequency. Besides the noise control application, Helmholtz resonators have been recently applied to acoustic energy harvesting. To date, most of studies on energy harvesting using Helmholtz resonators are employing piezoelectric materials located in the resonant volume and enhancing harvesting efficiency by tuning the resonance frequency and the structure of the added piezoelectric materials. In this study, a piezoelectric (PVDF composite) cantilever was integrated within a Helmholtz resonator. Then, energy harvesting efficiency was maximized by matching and tuning mechanical resonance of the piezoelectric cantilever and acoustic resonance of the Helmholtz resonator. Theoretical analysis including finite element simulation was also performed to confirm our experimental results. To maximize the harvest power, the electrical impedance matching was considered. This study can be applied to acoustic energy harvesting as well as acoustic noise control.