Harvesting Energy from Piezoelectrics Excited by Helmholtz Resonance: A Feasibility Study

Abstract

This project investigated the feasibility of converting wind energy to electrical energy using a Helmholtz resonator coupled with a matching frequency piezoelectric membrane. To explore the viability of such a system, different resonator geometries, orientations, and airflow speeds were analyzed to determine a configuration that produced an optimal scenario for energy production. This was accomplished by placing the designed device in a wind tunnel in a chosen configuration, and using the data to calculate the frequency and sound intensity of each system. On the electrical energy generation side, software programs Creo Parametric and ANSYS Mechanical were used to model a Channel 5804 lead zirconate titanate (PZT) piezoelectric membrane and simulate its frequency and voltage output due to a given oscillating sound pressure field. The experiments showed that the resonator produced higher sound intensities specifically at an orientation angle of 50 degrees to the flow and generally for lower cavity volumes, and that the effect of wind speed depended on the geometry. The optimal configuration for energy production was 3.0 L in resonator volume, a 50 degree orientation angle, and 10.2 m/s wind speed, which resulted in a maximum pressure of 46.9 Pa, an RMS pressure of 31.25 Pa, and a sound intensity of 2.37 W/m2. However, at a wind speed of 6.5 m/s, power density data suggests that the power output of a resonator array is comparable to that of a turbine wind farm. In this case, the system yielded a power density of a 2.14 W/m2, which compares to that of a wind farm at 2.59 W/m2. By simulating a transient pressure analysis to determine the effect of an oscillating pressure field on a matching-frequency piezo-electric membrane (85 Hz), ANSYS Mechanical rendered a best-case average voltage output of approximately 9.5 V.