四柱结构波浪绕射模型试验研究.docx

四柱结构波浪绕射模型试验研究
丛培文,滕 斌,章 康,黄一凡,勾 莹
( 大连理工大学海岸和近海工程国家重点实验室,辽宁大连 116024)
摘要: 张力腿平台的支撑结构由四根直立圆柱构成,四根支撑圆柱周围波面高度的计算对张力腿平台结构安全以及气隙设计具有重要意义。采用模型试验的方法对四柱结构的波浪绕射问题进行研究。试验中对柱体附近多个位置处的波面高度进行测量,通过对测量数据的统计分析,得到一阶和二阶水面波高分量幅值。为了验证绕射理论在计算波面高度上的适用性, 试验结果与数值模拟结果进行了对比。通过对比发现,即使波陡较大的情况下二阶绕射理论也可以很好地对波面高度进行模拟。同时,对发生在多柱结构内部的重要近场干涉现象也进行了观测。在特定的入射频率下,试验中观测到四柱结构内部流体发生明显的共振运动。
关键词: 四柱结构; 波面高度; 二阶绕射; 近场干涉; 海洋平台
中图分类号: P751 文献标识码: A
An experiment study for wave diffraction by a four-cylinder structure
CONG Pei-wen,TENG Bin,ZHANG Kang,HUANG Yi-fan,GOU Ying
( State Key Laboratory of Coastal and Offshore Engineering,Dalian University of Technology,Dalian 116024,China)
Abstract: The deck of tension leg platform is supported by four vertical columns and the prediction of the free surface elevation in the vicinity of the four supporting columns is significantly important for the structure safety and air gap design. An experiment is carried out to study the diffraction of regular waves by a four-cylinder structure. The experiments are designed to measure free surface elevation at multiple locations close to cylinder surface. By analysis of measured data,amplitudes of the first-order and second-order quantities are obtained. To examine the validation of the diffraction theory in predicting the free surface parison is carried out between the experimenta and numerical results. Even for high steepness,the second-order diffraction theory is shown to be effective to free surface elevation. Furthermore,the important phenomenon near trapping is investigated in the experiment. For specific incident wave frequency,obvious resonant wave motion can be observed inside the structure.
Key words: four-cylinder structure; wave elevation; second-order diffraction; near-trapping
在海洋平台的设计过程中,结构物周围波面高度的模拟对气隙设计具有重要的意义。气隙是指波峰与海洋平台下甲板间的垂直距离。一方面气隙大小必须充分以避免波浪冲击平台下甲板并造成设备的损坏。在 Eatock Taylor and Wu[1]以及 Swan 等[2]的研究中,报道了由海浪拍击造成的海洋平台甲板损坏事故; 另一方面要尽量减小气隙的大小以避免提升平台的重心高度以及增大平台的受风面积,从而避免增大海风对平台的作用力和倾覆力矩以及由此导致的对平台整体稳定性的影响。