A self-tunable wind energy harvester utilising a piezoelectric cantilever beam with bluff body under transverse galloping for field deployment

Abstract

Natural vibrations can be harnessed using piezoelectric transducers and converted into electrical energy to power small electronic devices such as sensors network for structural health monitoring. One promising wind energy harvester configuration is a piezoelectric cantilever beam with a bluff body attached at the free end. The strain-induced into the cantilever by the galloping motion, and therefore the power produced is dependent on the bluff body shape, wind speed and the incidence angle of the wind to the bluff body face. Thus far, most studies related to piezoelectric cantilever beam with transverse galloping bluff body were conducted in wind tunnels with laminar flow and graduated wind speed increase. There is no research conducted on natural and chaotic wind conditions. The effectiveness of the bluff body in varying wind conditions is not known. In this study, a self-tunable piezoelectric wind energy harvester was proposed by using a rotating base to account for the erratic nature of wind in the field. Three bluff body prisms (square, triangle and D-section), fitted to a piezoelectric cantilever with fixed and rotating bases, were sequentially studied under the natural wind condition. Results indicated that the rotating base configurations have a higher cut-in speed when compared with the motionless base but was able to produce higher output power, especially with the use of a square prism as the bluff body under typical urban windspeed (i.e. 3–6 m/s). This first-ever field study demonstrated the potential and advantage of employing the piezoelectric wind energy harvester with a rotating base under natural and erratic wind conditions.