Development of a piezoelectric wind energy harvester with hollow bluff body and tapered beam

Abstract Vortex-induced vibrations (VIV) based piezoelectric wind energy harvesters (PWEH) can serve as a sustainable alternative to batteries for microelectromechanical systems, but their output is limited by the lock-in region. To broaden the operational wind speed range and boost voltage output, a bluff body design featuring a tapered cantilever beam and a hollow cylindrical shape is proposed. This design was tested in two orientations based on the bluff body axis: horizontal, which oscillates vertically, and vertical, which oscillates laterally. Models with rectangular and tapered beams were compared through wind tunnel tests at wind speeds from 2 m/s to 10 m/s with an increment of 2 m/s, to assess how beam taper and PWEH orientation affect output voltage and displacement. Fifteen static pressure holes along the bluff body surface measured lift and drag coefficients, while a distance sensor recorded system displacement over time. The vertical PWEH with a tapered beam produced the highest effective output voltage of 0.5348 V at 8 m/s and exhibited the best overall performance across different wind speeds. Beam tapering is confirmed to enhance PWEH effectiveness. Performance of horizontal PWEH was generally lower than that of vertical PWEH and may have limited practical applications.