Research on the Fundamental Understanding of the Behavior of a Very Large Floating Structure in Waves

对超大型漂浮结构在波浪中行为的基本理解研究

• 批准号: 12650907
• 负责人: TAKAGI Ken
• 金额: $ 1.73万
• 依托单位: Osaka University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 2000
• 资助国家: 日本
• 起止时间: 2000 至 2002
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-12650907/
• 关键词: Mega-Float; Mat Type VLFS; Ray Method; Integral Equation; Hydro-elasticity; Zero-draft Approximation; Parabolic Approximation; Corner Problem; 漂流モーメント; 漂流力; 境界積分方程式; WKBJ近似; 放物近似

A concept of Very Large Floating Structure (VLFS) has been offered at the Mega-Float project in Japan that has a mat-like thin configuration while the horizontal scale is very large. They developed several computer codes to estimate the motion of VLFS, however the code is too time consuming and is not useful for the conceptual design. In order to solve this problem, the present study has started form formulating an integral equation which represents the hydro-elastic behavior of a VLFS in waves. Following results of the investigation of the integral equation, an application of the ray theory to hydro-elastic behavior of VLFS has been proposed. The theory itself is based on the classical ray theory, in which we used the fact that the hydro-elastic motion of VLFS can be regarded as wave propagation in the platform, and employed an assumption that the wavelength is very short compared with the horizontal size of VLFS. The classical ray theory insists that the wave field in and around the platform is represented as a summation of wave rays. The ray theory has been improved on two points. The shortcoming of the conventional ray theory is that the wave amplitude is suddenly changed along a ray that passes through a corner. This shortcoming is overcome by applying the parabolic approximation. The second improvement is that they extended the computer code to be applicable for arbitrary bottom, environmental and body geometry. Using this method, we demonstrated the influence of bottom topology and the influence of non-uniform rigidity of the structure and several interesting shapes of the structure have been offered to make motion of VLFS smaller. In order to demonstrate the accuracy of the present approach to the estimation of hydro-elastic behavior of VLFS, experiments in a small wave tank with a micro scale model has been also carried out. The ray method has been validated with experimental results.

日本的Mega-Float项目提出了超大型浮式结构物（VLFS）的概念，该浮式结构物具有席状薄结构，而水平尺度非常大。他们开发了几种计算机代码来估计VLFS的运动，但是代码太耗时，并且对于概念设计没有用处。为了解决这一问题，本研究从建立一个积分方程开始，该方程代表了波浪中VLFS的水弹性行为。根据积分方程的研究结果，提出了射线理论在超大型浮体水弹性特性中的应用。该理论本身是基于经典射线理论，其中我们使用的事实，即VLFS的水弹性运动可以被视为波在平台中的传播，并采用了一个假设，即波长是非常短的VLFS的水平尺寸相比。经典射线理论坚持认为，在平台和周围的波场表示为波射线的总和。射线理论在两点上得到了改进。传统射线理论的缺点是，波的振幅沿通过拐角的射线发生沿着突变。这个缺点是克服了应用抛物线近似。第二个改进是他们扩展了计算机代码，使其适用于任意的底部、环境和身体几何形状。利用这种方法，我们证明了底部拓扑结构的影响和结构的非均匀刚度的影响，并提供了几个有趣的结构形状，使VLFS的运动较小。为了证明本方法估计超大型浮体水弹性行为的准确性，还在带有微尺度模型的小型波浪池中进行了实验。射线法已与实验结果进行了验证。

项目成果

Takagi, K., Nagayasu, M.: "Hydroelastic Behavior of a Mat-Type Very Large Floating Structure of Arbitrary Geometry"Proc. of Oceans 2002, Honolulu. 2. 1923-1929 (2001)

Takagi, K., Nagayasu, M.：“任意几何形状的垫式超大型浮动结构的水弹性行为”Proc。

Takagi, K., Kohara, K.: "Application of the Ray-Theory to Hydro-Elastic Behavior of VLFS"Proc. of 10th Int. Offshore and Polar Eng. Conference. 1. 72-77 (2000)

Takagi, K.、Kohara, K.：“射线理论在 VLFS 水弹性行为中的应用”Proc。

高木 健: "VLFSの波浪中弾性挙動と漂流力に対するWKBJ近似の応用"関西造船協会誌. 第234号. 79-84 (2002)

Ken Takagi：“WKBJ 近似在 VLFS 波浪弹性行为和漂移力中的应用”《关西造船协会杂志》第 234. 79-84 号（2002 年）。

Takagi, K. and Kohara, K.: "Application of the Ray-Theory to Hydro-Elastic Behavior of VLFS"Proc. of 10th Int. Offshore and Polar Eng. Conference, Sheattle. 72-77 (2000)

Takagi, K. 和 Kohara, K.：“射线理论在 VLFS 水弹性行为中的应用”Proc。

Takagi, K. and Nagayasu, M.: "Hydroelastic Behavior of a Mat-Type Very Large Floating Structure of Arbitrary Geometry"Proc. of Oceans 2001, Honolulu. Vol.2. 1923-1929 (2001)

Takagi, K. 和 Nagayasu, M.：“任意几何形状的垫式超大型浮动结构的水弹性行为”Proc。