The performance of a self-excited fluidic energy harvester

TLDR

The available power in a flowing fluid scales with the cube of its velocity, indicating that substantial electrical energy can be harvested by exploiting the direct piezoelectric effect. The study experimentally investigates a self‑excited piezoelectric energy harvester in uniform steady flow, including the effect of non‑rigid bonding on strain transfer. The harvester consists of a cylinder mounted on a cantilevered beam partially covered by piezoelectric patches, and fluid–structure interaction induces oscillatory forces that deflect the beam, strain the patches, and generate charge; strain data are used with a distributed‑parameter model to predict voltage, and non‑rigid bonding effects are examined. In a wind tunnel, the device produced about 0.1 mW of non‑rectified power at 1.192 m s⁻¹, with an aero‑electromechanical efficiency of 0.72 %, power densities of 23.6 mW m⁻³ and 233 W m⁻³, and the rigid‑bonding assumption overestimated power by >60 % while a non‑rigid model reduced the error to <10 %.

Abstract

The available power in a flowing fluid is proportional to the cube of its velocity, and this feature indicates the potential for generating substantial electrical energy by exploiting the direct piezoelectric effect. The present work is an experimental investigation of a self-excited piezoelectric energy harvester subjected to a uniform and steady flow. The harvester consists of a cylinder attached to the free end of a cantilevered beam, which is partially covered by piezoelectric patches. Due to fluid–structure interaction phenomena, the cylinder is subjected to oscillatory forces, and the beam is deflected accordingly, causing the piezoelectric elements to strain and thus develop electric charge. The harvester was tested in a wind tunnel and it produced approximately 0.1 mW of non-rectified electrical power at a flow speed of 1.192 m s−1. The aeroelectromechanical efficiency at resonance was calculated to be 0.72%, while the power per device volume was 23.6 mW m−3 and the power per piezoelectric volume was 233 W m−3. Strain measurements were obtained during the tests and were used to predict the voltage output by employing a distributed parameter model. The effect of non-rigid bonding on strain transfer was also investigated. While the rigid bonding assumption caused a significant (>60%) overestimation of the measured power, a non-rigid bonding model gave a better agreement (<10% error).