The presence of a bluff body upstream of a cantilever beam promotes persistent, aero-elastic vibrations of the beam. Vortex-induced vibration in an array of two mutually interacting bluff bodies in such configurations undergoing two-degrees of freedom transverse oscillation has not been investigated before. In the present work, we have studied experimentally, the unsteady response of an array of two similar rigid cylinders, positioned side-by-side in reference to the freestream velocity, each one mounted on the upstream end of an elastic cantilever beam. By fitting the beams with piezoelectric layers, these configurations are converted to piezoelectric fluid energy harvesters (PFEH) that can extract small amounts of energy from the flow. Comparing the performance of linear (L-PFEH), non-linear (NL-PFEH), and a non-linear array (NLA-PFEH) of harvesters show that NLA-PFEH has the widest broadband operating velocity range and the greatest generated power followed by NL-PFEH and then L-PFEH. The maximum electric power output of NLA-PFEH was ~1000% greater than for NL-PFEH with a corresponding ~250% increase in the operating velocity range. Different cylinder configurations reveal the presence of hysteresis in the behavior of NLA-PFEH when the distance between the cylinders (so-called cylinder gap to diameter ratio), G/D < 0.5. At large distances from each other (G/D ≥ 4), the two cylinders behave like independent, isolated harvester units with rather weak mutual interaction.

中文翻译：

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非线性压电流体能量收集器：两个振荡圆柱体的相互作用

悬臂梁上游钝体的存在促进了梁的持续气动弹性振动。在经历两个自由度横向振荡的这种配置中，两个相互相互作用的钝体阵列中的涡激振动以前没有被研究过。在目前的工作中，我们通过实验研究了两个类似刚性圆柱体阵列的非稳态响应，参考自由流速度并排放置，每个圆柱体都安装在弹性悬臂梁的上游端。通过将梁与压电层配合，这些配置被转换为压电流体能量收集器 (PFEH)，可以从流体中提取少量能量。比较线性（L-PFEH）、非线性（NL-PFEH）的性能，采集器的非线性阵列 (NLA-PFEH) 表明，NLA-PFEH 具有最宽的宽带工作速度范围和最大的发电功率，其次是 NL-PFEH，然后是 L-PFEH。NLA-PFEH 的最大电功率输出比 NL-PFEH 高约 1000%，操作速度范围相应增加约 250%。当圆柱体之间的距离（所谓的圆柱体间隙与直径之比）G/D < 0.5 时，不同的圆柱体配置揭示了 NLA-PFEH 行为中存在滞后现象。在彼此相距很远的地方 (G/D ≥ 4)，两个气缸表现得像独立的、孤立的收割机单元，相互作用相当弱。NLA-PFEH 的最大电功率输出比 NL-PFEH 高约 1000%，操作速度范围相应增加约 250%。当圆柱体之间的距离（所谓的圆柱体间隙与直径之比）G/D < 0.5 时，不同的圆柱体配置揭示了 NLA-PFEH 行为中存在滞后现象。在彼此相距很远的地方 (G/D ≥ 4)，两个气缸表现得像独立的、孤立的收割机单元，相互作用相当弱。NLA-PFEH 的最大电功率输出比 NL-PFEH 高约 1000%，操作速度范围相应增加约 250%。当圆柱体之间的距离（所谓的圆柱体间隙与直径之比）G/D < 0.5 时，不同的圆柱体配置揭示了 NLA-PFEH 行为中存在滞后现象。在彼此相距很远的地方 (G/D ≥ 4)，两个气缸表现得像独立的、孤立的收割机单元，相互作用相当弱。