摘要
在复杂的海洋载荷作用下,沿深海细长柔性管常出现多模态振动特征。文中首先采用双向流固耦合技术,实施了剪切流与均匀流作用下弹性管涡激振动的数值仿真。其次,利用位置-频率-能量谱分析方法,探讨了沿管轴向的多模态耦合振动响应。最后,使用一种全新的模态分解技术,对管体特定位置的振动响应信号进行自适应分解,由分解产生的固有模态函数分析振动过程的时频特征,进而获得弹性管振动模态的瞬态演变规律。研究发现:细长弹性管的多模态振动现象较为普遍;随着流速的增加,高阶振动模态不断被激发出,伴随着模态间的能量传递,各显性模态在不同时段竞争激烈,常出现瞬态共存现象。通过时间-频率-能量Hilbert谱分析发现,由局部旋涡脱落与临近管段振动能量传递共同引起的随机振动模态及固有振动模态在较宽的频带范围内发生,且各显性振动模态的能量通常都是时变的。
The multimode vibration characteristics associated with slender marine risers/pipes are widely seen in the case of complex marine environments.Firstly,by using a two-way fluid-structure interaction technique,numerical simulations were performed on the vortex-induced vibration of a flexible marine riser model subjected to shear and uniform flows.Secondly,based on the analysis of position-frequency-energy spectra,the multimode characterized vibration along the pipe span was investigated.Then,an empirical mode decomposition technique called FB-EMD,based on the Fourier transform and band-pass filter,was used to adaptively decompose the vibration data into some intrinsic mode functions.By analyzing the time-frequency characteristic information,the transient evolution characteristics of the vibration modes associated with the flexible riser model were then discovered.It is found that the phenomena of multimode vibration along the slender flexible pipes are quite common.With the increase of flow velocity,higher order vibration modes are continuously triggered,and with the energy transfer between modes,the apparent modes at different periods compete fiercely,often resulting in transient multimode coexistence.The time-frequency-energy Hilbert spectral analysis shows that the random and natural vibration modes caused by the combined effects of local vortex shedding and energy transfer from adjacent pipe sections are excited in a wide frequency band,and the energy of each dominant vibration mode is usually time-varying.
作者
韩家明
陈正寿
HAN Jia-ming;CHEN Zheng-shou(School of Naval Architecture and Maritime,Zhejiang Ocean University,Zhoushan 316022,China)
出处
《船舶力学》
北大核心
2025年第11期1768-1781,共14页
Journal of Ship Mechanics
基金
国家自然科学基金资助项目(41776105)
浙江省自然科学基金资助项目(LY20E090003)。
关键词
涡激振动
模态分解技术
多模态振动
能量传递
vortex-induced vibration
mode decomposition technique
multimode vibration
energy transfer
