Piezoelectric vibration energy harvesting has attracted considerable attention because of its prospects in self-powered electronic applications. There are a many low-velocity waters in nature, such as rivers, seas and oceans, which contain abundant hydrokinetic energy. In this paper, an optimal geometric piezoelectric beam combining magnetic excitation is identified and applied to a vortex-induced vibration energy harvester (ViVEH) for low velocity water flow, which is composed of a continuous variable-width piezoelectric beam carrying a cylindrical bluff body. The finite element simulation and experiment are first carried out to study the harvesting characteristics of the designed variable-width beam ViVEH without considering the magnetic excitation. The influence of the width-ratio and flow velocity on the harvesting voltage is studied in detail. The optimal structure, a ViVEH equipped with triangular piezoelectric beam, is then obtained by the superior energy harvesting performance for low velocity water flow. From the experimental results, at a flow velocity of 0.6 m/s, the highest root mean square (RMS) voltage and RMS voltage per unit area are 19.9 V and 0.07 V/mm², respectively. Furthermore, magnetic excitation is introduced to improve the scavenging performance of the optimal triangular beam ViVEH, different polarity arrangements are compared, and the optimal case, the arrangement of horizontal repulsion and vertical attraction (HR-VA), is obtained. This case can scavenge the highest power of 173 μW at a flow velocity of 0.5 m/s, which is increased by 127% compared to a conventional constant-width beam ViVEH with no magnetic excitation.

压电振动能量收集由于其在自供电电子应用中的前景而备受关注。自然界中有许多低速水域，例如河流，海洋和海洋，它们含有丰富的动能。本文确定了结合磁激励的最优几何压电梁，并将其应用于低速水流的涡激振动能量收集器（ViVEH），该振动器由承载圆柱状钝体的连续可变宽度压电梁组成。首先进行了有限元模拟和实验，以研究设计的变宽光束ViVEH的收割特性，而无需考虑磁激励。详细研究了宽度比和流速对收获电压的影响。然后，通过低速水流的卓越能量收集性能，可获得配备三角压电梁的ViVEH最佳结构。根据实验结果，在流速为0.6 m / s时，每单位面积的最高均方根（RMS）电压和RMS电压分别为19.9 V和0.07 V / mm^2个。此外，引入磁激励以改善最佳三角光束ViVEH的扫气性能，比较了不同极性的布置，并获得了最佳情况，即水平排斥力和垂直吸引力（HR-VA）。这种情况可以在流速为0.5 m / s的情况下清除173μW的最高功率，与没有磁激励的常规等宽光束ViVEH相比，增加了127％。