Improving low-wind-speed aero-elastic responses by peanut-shaped auxetic structure for galloping energy harvesting

The galloping energy harvester (GEH) is a promising wind energy harvesting solution for powering the Internet of Things (IoT) and wireless sensor networks (WSNs). However, conventional GEHs face bottlenecks such as high critical wind speeds and low energy-harvesting efficiency under weak wind conditions. This work introduces a peanut-shaped auxetic structure into the GEH system, proposing a novel peanut-shaped auxetic galloping energy harvester (AGEH). The proposed design enhances energy conversion performance through two mechanisms: reducing the stiffness of the cantilever beam and modifying the aerodynamic flow field characteristics around the bluff body. The vibration response and energy harvesting behavior of a plain galloping energy harvester (PGEH) with a cuboid bluff body (PGEH-Cuboid), an AGEH with a cuboid bluff body (AGEH-Cuboid), and an AGEH with a peanut-shaped profiled bluff body with porosity K = 0.4 and shape coefficient M = 8.5 (AGEH-( K = 0.4, M = 8.5)) are evaluated numerically and experimentally. Compared to the PGEH-Cuboid, the AGEH-Cuboid initiates vibration at 2.4 m/s, and increases the maximum root mean square voltage ( V rms ) by 332.96%. The peanut-shaped bluff body further increases the overall average output power (OAOP) by 100.23% relative to the cuboid bluff body. Three-dimensional computational fluid dynamics (3D-CFD) simulations elucidate the flow mechanism through which the peanut-shaped bluff body enhances aerodynamic forces by increasing wake vortex size and accelerating boundary layer separation. Application tests confirm that the proposed AGEH can serve as a reliable alternative power source for low-power electronic devices.