摘要
以四柱半潜式平台为研究对象,基于模型试验方法分析不同系泊刚度下的平台涡激运动(VIM)特征。由于涡激运动对系泊系统极限张力和疲劳寿命的重要贡献,因此重点研究系泊刚度对平台横向涡激响应的影响。结果显示:系泊系统刚度的变化对横向涡激运动的最大响应幅值影响较小,运动响应曲线随无量纲折合速度的分布趋势基本一致;但相同流速下平台具有完全不同的涡激运动响应特性,这表明若当前流速引起了平台大幅度的涡激运动,可通过调节系泊线预张力来改变系泊系统的刚度,使其固有频率避开平台旋涡脱落的频率范围,从而抑制平台的横向涡激运动;当平台受到来自不同方向的水流作用时,需采用不同的刚度调整策略。此外,文中还详细分析了平台在XY平面上的涡激运动轨迹、涡激锁定现象如共振和频率锁定、不同系泊刚度下涡激响应的谱。相关结论对实际平台作业具有重要的参考价值,为处于涡激共振状态下的平台运动抑制提供了一种新的思路。
This study is aimed to experimentally investigate the characteristics of vortex-induced motion(VIM)with different mooring system stiffness on a semi-submersible platform with four columns.The effects of mooring stiffness on VIM in the transverse direction are mainly discussed due to its important contribution to the extreme tension and fatigue life of mooring lines.The result shows that the stiffness of the mooring system has little effect on the maximum amplitude of VIM in the transverse direction and that the distribution trend of the motion curve according to the non-dimensional reduced velocities is almost the same.However,the platform has completely different vortex-induced motion response characteristics under the same velocity with different mooring stiffness,which indicates that the stiffness of the mooring system may be changed by adjusting mooring line pretension,such that the natural frequencies will not be within the vortex shedding range and the motion in the transverse direction can be suppressed if the existing flow velocity has given rise to vortex-induced motion.Furthermore,different strategies for adjusting stiffness should be applied if the platform is subjected to current incidences from different directions.In addition,VIM trajectories in the XY plane,vortex lock-in phenomena such as resonance and lock-in frequency,and motion spectra for different mooring stiffness are also analyzed in detail.The conclusions provide an important reference for actual platform operation and new ideas for suppressing the motion of platforms with VIM.
作者
单铁兵
许玉旺
任铁
SHAN Tie-bing;XU Yu-wang;REN Tie(Marine Design&Research Institute of China,Shanghai 200011,China;State Key Laboratory of Ocean Engineering,Shanghai Jiao Tong University,Shanghai 200240,China)
出处
《船舶力学》
EI
CSCD
北大核心
2022年第12期1785-1796,共12页
Journal of Ship Mechanics
基金
工业和信息化部高技术船舶科研计划资助项目([2016]546号)。
关键词
涡激运动(VIM)
横向运动
刚度影响
运动轨迹
锁定现象
vortex-induced motion(VIM)
transverse motion
stiffness effect
motion trajectory
lock-in phenomenon
