Abstract When the VIVACE converter is operated in shallow water, the free surface in its proximity plays a critical role in affecting the dynamic response and the consequent energy harvesting performance of the converter. In this study, a series of experimental tests are conducted for the flow-induced vibration of a single-cylinder VIVACE converter in the TrSL3 regime with the Reynolds number 34 , 931 R e 116 , 370 close to a free surface to examine this effect. The cylinder is placed beneath the free surface with a gap of 3 . 0 D where D is the cylinder diameter and free to vibrate in the transverse direction only. The virtual damper–spring system is adopted to provide the damping and restoring forces. The values of the harnessing damping ratio considered are ζ h a r n e s s = 0 . 04 , 0.08, 0.12, 0.16 and 0.20 and the spring stiffness ranges from 600 to 1200 N/m. The amplitude response, frequency response, harnessed power and energy harnessing efficiency are investigated. When the VIVACE converter is in the vicinity of the free surface, the vortex-induced vibration (VIV) is initiated at a lower reduced velocity. Both the VIV and galloping regions are enlarged with a smoother transition between the two regimes. The harnessed power P h a r n e s s in the VIV region is slightly lower while higher P h a r n e s s is found in the galloping region. The efficiency of the cylinder near the free surface is lower in the VIV region and analogous to that in the deep submerged case when the cylinder is undergoing galloping. For a VIVACE converter placed near the free surface, its flow-induced vibration (FIV) and energy conversion features vary similarly with the damping and stiffness parameters to the far away from the free surface configuration. Overall, given that the governing parameters are carefully selected, it is viable to use the VIVACE converter close to the free surface for harnessing the hydrokinetic energy efficiently.

中文翻译：

---

用于从自由表面附近的流动诱导振动中收集流体动能的单缸 VIVACE 转换器的性能

摘要 当 VIVACE 转换器在浅水中运行时，其附近的自由表面在影响转换器的动态响应和随之而来的能量收集性能方面起着至关重要的作用。在这项研究中，对雷诺数 34、931 R e 116、370 接近自由表面的 TrSL3 状态下单缸 VIVACE 转炉的流动诱导振动进行了一系列实验测试，以检查这种影响。圆柱体放置在自由表面下方，间隙为 3 。0 D 其中 D 是圆柱体直径，只能在横向自由振动。采用虚拟阻尼弹簧系统来提供阻尼和恢复力。考虑的线束阻尼比值为 ζ线束 = 0 。04、0.08、0.12、0.16 和 0。20，弹簧刚度范围为 600 至 1200 N/m。研究了幅度响应、频率响应、利用功率和能量利用效率。当 VIVACE 转换器在自由表面附近时，涡激振动 (VIV) 以较低的降低速度开始。VIV 和 galloping 区域都扩大了，两个区域之间的过渡更平滑。VIV 区域的功率 P 线束略低，而驰骋区域的 P 线束更高。接近自由表面的圆柱体在 VIV 区域的效率较低，类似于在深潜情况下圆柱体正在疾驰时的效率。对于放置在自由表面附近的 VIVACE 转换器，其流致振动 (FIV) 和能量转换特性与远离自由表面配置的阻尼和刚度参数相似。总的来说，考虑到控制参数是经过精心选择的，在靠近自由表面的地方使用 VIVACE 转换器来有效地利用流体动能是可行的。