Extending limits for wave power absorption by axisymmetric devices
Extending limits for wave power absorption by axisymmetric devices
复制标题
扩大轴对称装置吸收波浪能的限制
DOI：
10.1017/jfm.2021.645
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发表时间：
2021
影响因子：
3.7
通讯作者：
D. Greaves
中科院分区：
文献类型：
--
作者：
R. Porter;S. Zheng;D. Greaves
摘要：20世纪70年代建立了刚体运动轴对称波能转换器吸收波长为$\lambda$的单色水波能量的理论极限。装置吸收升沉运动产生的最大平均功率相当于$\lambda /2{\rm \pi}$入射波峰长度所含的功率。对于通过浪涌和/或俯仰运动吸收的设备，所谓的捕获宽度加倍到$\lambda /{\rm \pi}$。对于同时吸收升沉和浪涌/俯仰的装置，捕获宽度进一步增加到$3\lambda /2{\rm \pi}$。在本文中，证明了通过使用广义（非刚体）运动模式，在理论上可以扩展轴对称波能转换器的捕获宽度而不受约束。这个概念适用于垂直圆柱体，其表面被一系列狭窄的垂直吸收桨包围。对桨运动作了连续统近似，简化了问题，并允许制定策略来设置控制功率吸收的弹簧和阻尼器。结果表明，一个固定尺寸的圆柱体可以吸收平面入射波所需的尽可能多的功率，尽管线性理论的实际限制随着需求的增加而迅速突破，除非圆柱体的尺寸成比例地增加。在本文中，我们没有详细探讨这些限制或进一步的实际设计考虑，例如施加运动约束。用离散桨叶模拟测试了连续统近似的精度。
Abstract The theoretical limit for absorption of energy in monochromatic water waves of wavelength $\lambda$ by axisymmetric wave energy converters operating in rigid-body motion was established in the 1970s. The maximum mean power generated by a device absorbing due to heave motion is equivalent to that contained in $\lambda /2{\rm \pi}$ length of an incident wave crest. For devices absorbing through surge and/or pitch motions the so-called capture width doubles to $\lambda /{\rm \pi}$. For devices absorbing in both heave and surge/pitch the capture width increases further to $3\lambda /2{\rm \pi}$. In this paper it is demonstrated that it is theoretically possible to extend the capture width for axisymmetric wave energy converters without bound through the use of generalised (non-rigid-body) modes of motion. This concept is applied to vertical cylinders whose surface is surrounded by an array of narrow vertical absorbing paddles. A continuum approximation is made to the paddle motion which simplifies the problem and allows strategies to be developed for setting the springs and dampers that control the power absorption. Results demonstrate that a cylinder of fixed size can absorb as much power as demanded from a plane incident wave although the practical limitations of linear theory are rapidly breached as that demand increases unless the size of the cylinder increases in proportion. In this paper we do not explore these limits in detail or further practical design considerations, such as imposing motion constraints. The continuum approximation is tested against a discrete paddle simulation for accuracy.