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

基本信息

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

项目摘要

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.

在日本的Mega-LoaT项目中，已经提供了非常大的浮动结构（VLF）的概念，该项目具有MAT状的薄构型，而水平尺度非常大。他们开发了几个计算机代码来估计VLF的运动，但是该代码太耗时，对于概念设计并不有用。为了解决这个问题，本研究已经开始形成一个整体方程，该方程代表了波浪中VLF的水力弹性行为。根据对积分方程的研究结果，已经提出了射线理论在VLF的水力弹性行为中的应用。该理论本身基于经典射线理论，在该理论中，我们使用了这样一个事实，即VLF的水力弹性运动可以被视为平台中的波传播，并采用了一个假设，即波长与水平尺寸相比非常短。 VLFS。经典射线理论坚持认为，平台内和周围的波场表示为波浪的总和。射线理论在两个点上得到了改善。传统射线理论的缺点是，波幅度突然沿着射线穿过角落变化。通过应用抛物线近似值来克服这种缺点。第二个改进是，它们扩展了计算机代码以适用于任意底部，环境和身体几何形状。使用这种方法，我们证明了底部拓扑的影响以及结构的不均匀刚性的影响以及结构的几种有趣的形状，以使VLF的运动较小。为了证明目前的VLF估算水力弹性行为的准确性，还进行了具有微尺度模型的小波罐中的实验。射线方法已通过实验结果进行了验证。