Energy, Vol.183, 92-105, 2019
Fork-shaped bluff body for enhancing the performance of galloping-based wind energy harvester
Galloping-based piezoelectric energy harvesting systems are being used to supply renewable electricity for the low-power wireless sensor network nodes. In this paper, a fork-shaped bluff body is presented as the basic system component, and demonstrated by experiments and simulations to improve the harvesting efficiency at low wind speed. For the fork-shaped structure, the fluid simulation results via CFD (Computational Fluid Dynamics) indicate that the '(sic)'-shaped region formed by two protruding front blades can help strengthen the vorticity to obtain high air lift force. The '(sic)'-shaped region formed by the middle transverse blade and the rear blade can induce a large pressure difference between two sides of the rear blade. The experimental results demonstrate that compared with the traditional bluff bodies such as triangular prism and square prism, the piezoelectric wind energy harvester with the fork-shaped structure can generate much higher output voltages. When the ratio (l(f)/W) of the front blade length (l(f)) to the bluff body width (W) is 1/4, the fork structure can induce the best harvesting performance. Further, by adding cover plates on two ends of the bluff body, the energy harvesting efficiency can be further improved in a wider blade length ratio (l(f)/W = 0.75 similar to 1) range. (C) 2019 Elsevier Ltd. All rights reserved.