Investigation into the performance of galloping piezoelectric energy harvesters with two symmetrical splitters in different arrangements

Abstract

To enhance the efficiency of wind energy harvesters, aerodynamic modifications to bluff bodies prove highly effective. This study introduces two innovative galloping piezoelectric energy harvesters (GPEHs) equipped with two symmetrical splitters on a cuboid bluff body: GPEH with upstream splitters (GPEH-US) and GPEH with downstream splitters (GPEH-DS). Wind tunnel experiments evaluated the impact of splitter angle and length on energy harvesting performance across varying wind speeds. The results indicate that larger splitter angles and shorter lengths are more favorable for energy harvesting in GPEH-US. The optimal configuration, determined as GPEH-US with α = 90° , L = 0.4D , reduces the threshold wind speed, expands the effective wind speed range for energy harvesting, and increases maximum voltage and power output by over 99%, 301%, respectively, compared with conventional GPEH. Conversely, GPEH-DS are less effective for energy harvesting but demonstrate potential in vibration control applications. Computational fluid dynamics (CFD) simulations using the OpenFOAM toolbox qualitatively elucidate the physical mechanisms driving these results. A larger splitter angle enables secondary small-scale vortices (SV) to absorb more energy, accelerates boundary layer separation, intensifies and disorderly vortex shedding, enhances aerodynamic instability, and improves energy harvesting performance.