A magnetically coupled cross-axis bluff-body energy harvester using lightweight HDPE-based magnetic composites for low-speed wind energy application

Abstract

This study proposes a wind-induced energy harvesting device integrating HDPE-based magnetic composites with a cross-axis dual-bluff-body configuration for low wind-speed conditions. Two bluff bodies are mounted on cantilever beams in horizontal and vertical orientations to enhance flow-induced vibrations. Lightweight magnetic composites were fabricated using HDPE reinforced with barium ferrite (BaFe₁₂O₁₉), iron oxide (Fe₃O₄), and neodymium–iron–boron (NdFeB) fillers. The composites reduce structural weight while providing sufficient magnetic properties for effective coupling. Experimental results show that higher magnetic field intensity and attractive polarity enhance vibration response and electrical power generation. The NdFeB composite with 70% filler loading achieved the best performance. Under optimal conditions, with a magnet spacing-to-bluff-body width ratio of 0.25 and a magnetic field intensity of 180 mT, the device achieved a cut-in wind speed of 2 m/s and a maximum electrical power output of 16.18 mW. Particle Image Velocimetry (PIV) analysis indicated that the enhanced performance resulted from the combined effects of vortex-induced aerodynamic forces and magnetic induction forces. The optimal spacing promoted stronger fluid–structure coupling, amplifying vibration and power generation. These findings demonstrate the potential of lightweight magnetic composites for low-speed wind energy harvesting.