Experimental study of wind energy harvesting from flow-induced vibration of prisms using magnetostrictive material

A vibration energy harvester was developed using a magnetostrictive material as a power generator and a prism as a wind receiver to harvest energy from low-speed wind by exploiting flow-induced vibration. The present cantilevered vibration power generator has originality for the structure which consists of a U-shaped unimorph beam of Galfenol (iron-gallium alloy). Wind tunnel experiments were conducted for prisms having circular, rectangular, filleted triangular, and V-shaped cross-sections. We focused on transverse vortex-induced vibration for a circular cylinder and low-speed galloping vibration for a rectangular prism with a depth-to-height ratio of 0.2, a filleted triangular prism, and a V-shaped prism. The effect of the width of prisms having a span length of L = 200 mm on the transverse vibration characteristics and the power extracted from the vibration generator was investigated. The maximum power generated by cylindrical, rectangular, filleted triangular, and V-shaped prisms with heights of 50, 50, 60, and 50 mm was 1.28, 3.5, 7.83, and 5.02 mW, respectively. These maximum power levels are enough to run a wireless sensor. Moreover, the angle of the V-shaped prism having a width of 50 mm was varied (i.e., β=60°, 90°, 120°, and 150°) and tested in wind tunnel experiments. The V-shaped prism with β=120° was best from several viewpoints, including low excitation wind speed, safe operation at high wind speed, efficient operation in environmental conditions, and sustainability.