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Small-scale energy harvesting from ambient vibration induced by aerodynamic instabilities can be used for wireless sensing applications. The configuration with a bluff body attached to a piezoelectric cantilever has been exploited in many studies. For low-wind energy harvesting, vortex-induced vibration is investigated more frequently than other types of flow-induced motions, such as galloping and flutter, because of its quasisteady behavior called the potential lock-in phenomenon. In practice, a stationary square column is placed before the energy harvester to generate wake shedding, which can broaden the bandwidth of the energy harvester compared with a pure energy harvester equipped with a single bluff body. This paper presents a proposed CFD method coupled with an electromechanical model to predict the performance of the energy harvester. The proposed approach is verified with our experimental setup. The time history of the voltage output and the frequency response is obtained by performing the relevant experiments. A subsequent CFD study is performed to investigate the flow patterns of the present energy harvesting system.

This study aims to improve the performance of the galloping-based piezoelectric energy harvester (GPEH) by benefiting from two half-cylinder obstacles. Two half-cylinder obstacles are employed to construct a variable cross-section tube which changes the airflow characteristics near the GPEH placed inside. The performance of the GPEH in the variable cross-section tube is tested by wind tunnel experiments. The experimental results show that compared with the traditional GPEH, the cut-in speed of the GPEH with the two half-cylinder obstacles at the downstream position -1.5D is reduced by 43.87%, from 2.23 m/s to 1.55 m/s. For the highest experimental wind speed of 4.29 m/s, the output voltage of the GPEH with the two half-cylinder obstacles is increased by 109.28 %, from 4.31 V to 9.02 V. Moreover, the performance of the GPEH with the obstacles can be improved by appropriately increasing the obstacle curvature and reducing the throat width.The computational fluid dynamics (CFD) simulations are conducted to qualitatively interpret the experimental discoveries. The results demonstrated that the downstream area is beneficial to the GPEH, whereas the upstream area degrades the performance.