Excitation Forces on Point Absorbers Exposed to High Order Non-linear Waves
Excitation Forces on Point Absorbers Exposed to High Order Non-linear Waves
复制标题
暴露于高阶非线性波的点吸收器上的激励力
DOI：
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发表时间：
2013
期刊：
影响因子：
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通讯作者：
M. Jakobsen
中科院分区：
文献类型：
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作者：
Thomas Viuff;M. T. Andersen;M. Kramer;M. Jakobsen
波浪能装置通常位于靠近自由水面的中水或浅水中，这些地方的波浪暴露是极端的。结构通常由对压力载荷敏感的大型薄弯曲板、球壳或圆柱形结构组成。由于缺乏适当的设计压力分布计算方法，导致了波能原型的壳屈曲等结构破坏。为了进一步理解高阶非线性波的复杂载荷，本文提出了一种实用的方法来估计考虑非线性和衍射效应的波激励力。该方法已通过带有6轴力传感器的半球形点吸收器的实验室实验进行了验证，但该技术被认为适用于大多数类型的水下或半水下浮动装置。应用的方法是基于峰值力系数的计算，其定义为实验测量的结构力除以所选理论方法估计的力。所使用的方法包括对结构表面上的未扰动波压力进行积分，对应于弗劳德-克雷洛夫力，以及线性势衍射理论的数值解。由于这两种方法在描述高次波和衍射时都有相互的局限性，因此将介绍两种方法的结合。
Wave energy devices are often located in intermediate or shallow water close to the free water surface where the wave exposure is extreme. The structures typically consist of large thin curved plates, spherical shells, or cylindrical structures which are sensitive to pressure loads. The lack of proper methods to calculate design pressure distributions has led to structural failures such as buckling in the shells in wave energy prototypes. As a step towards understanding the complex loading from high order non-linear waves, this paper presents a practical approach to estimate wave excitation forces accounting for both non-linearity and diffraction effects. The method is validated by laboratory experiments using a hemispherical point absorber with a 6-axis force transducer, but the technique is believed to be applicable for most types of submerged or semi-submerged floating devices. The applied method is based on calculation of a peak force coefficient defined as experimentally measured forces on the structure divided by forces estimated by the chosen theoretical method. Methods used include an integration of the undisturbed wave pressure over the surface of the structure, corresponding to the Froude-Krylov force, and a numerical solution to linear potential diffraction theory. Since the two methods have mutual limitations in describing higher order waves and diffraction, a combination of the two will be introduced.