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THE PREDICTION OF WAVE-INDUCED MOTION AND MOORING FORCES FOR FLOATING OFFSHORE STRUCTURES

海上浮动结构的波感运动和系泊力的预测

基本信息

批准号：
61460177
负责人：
MATSUI TETSUYA
金额：
$ 4.61万
依托单位：
NAGOYA UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (B)
财政年份：
1986
资助国家：
日本
起止时间：
1986 至 1987
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-61460177/
关键词：
Floating offshore structures Irregular waves Moored vessel Wave drift force 長周期運動

项目摘要

A series of theoretical and experimental investigations have been conducted to predict the slow drift motion and mooring line forces for floating structures in irregular sea waves. The resluts obtained from this project are summarized as follows:(1) An exact method for simulating the slow drift motion and mooring line forces for floating offshore structures has been proposed within the framework of the second order potential flow theory. The method has been applied to understand the slow drift behaviour of such structures as an articulated column and a moored semi-submersible. It was confirmed that the simulated time histories of the slow drift motion of the semi-submersible are in fairly good agreement with the measured ones in model tests, if the viscous damping term is evaluated appropriately, say by means of the Morison formula.(2) A specific instrument for the random forced oscillation test has been manufactured to measure the hydrodynamic forces on an articulated column model in the low frequency motion. The effects of the high frequency motion of the column and the incoming waves on the hydrodynamic forces have been investigated in dateil. The conclusions arising from the test are listed in the following:a) The hydrodynamic damping of the articulated column in the low frequency motion is mainly due to viscous effects.b) Such damping forces are strongly influenced by the presence of the high frequency motion of the column as well as the incoming waves. Due to small number of the measured data their significant scatter observed. it is difficult at the present stage to predict quantitatively the hydrodynamic forces on the column in the low frequency motion. This will be a matter for future research.

对浮式结构物在不规则海浪中的慢漂运动和系缆力进行了一系列的理论和试验研究。(1)在二阶势流理论的框架下，提出了浮式海洋结构物慢漂运动和系缆力的精确模拟方法。该方法已被用于了解铰接柱和系泊半潜器等结构的慢漂特性。结果表明，在适当估计粘性阻尼项的情况下，半潜器慢漂移运动的模拟时程与模型试验的实测值吻合较好。(2)研制了用于测量铰接柱模型低频运动水动力的随机强迫振动试验专用仪器。文中还研究了柱子的高频运动和入射波浪对水动力的影响。试验结果表明：(1)铰接柱在低频运动时的流体动力阻尼主要是由于粘性效应引起的；(2)这种阻尼力受柱体的高频运动和波浪的影响很大。由于测量数据数量较少，观测到其明显的散射性。在现阶段，很难定量地预测柱子在低频运动时所受的水动力。这将是未来研究的问题。