EI、Scopus 收录
中文核心期刊

含分布浮体的复杂构型深海缆线的动响应及其时空演化

DYNAMIC RESPONSE AND SPATIAL-TEMPORAL EVOLUTIONS OF DEEP-WATER COMPLEX CONFIGURATION CABLES WITH DISTRIBUTED BUOYANCY MODULES

  • 摘要: 深水柔性缆线是深海资源开采系统的重要组成部分, 随着水深的增加, 深水缆线长径比达103, 结构柔性变得很大, 且沿展向非均匀分布的浮力模块, 使得缆线构型变得更加复杂、张力等结构参数沿展向变化, 这使得环境载荷作用、海面船体运动等激励作用下的缆线流固耦合响应变得更加复杂, 给结构安全带来严峻挑战. 本文针对Double-stepped这种新构型深水缆线, 基于其流固耦合特性和载荷模型表征, 建立了含分布浮体的深水缆线动力学控制方程, 并结合有限元数值模拟和水箱模型实验, 进行了复杂构型缆线的动响应研究. 考察规则波和极端波浪环境载荷作用、海面船体运动等激励因素对结构响应的影响, 给出位移和张力等响应的时空演化规律, 并基于WKB理论分析了变参数结构响应幅值和波长的演化规律和机理. 结果表明: 结构响应沿着缆线长度向下传播过程中非单调变化, 在低张力区域会出现局部峰值; 由于分布浮体的存在使得结构参数轴向变化且不连续, 响应时空演化变得更加复杂, 呈现驻波、行波混合效应, 而且张力不但会影响位移幅值, 还会引起响应传播过程中的波长改变.

     

    Abstract: Long flexible cables is one of important parts of complex systems used in explorations and exploitations of ocean resources, particularly in deep or even ultra-deep water. These flexible cables, with large aspect ratio usually at level of 103, need to be installed with distributed buoyancy modules along its body length. In that case, these distributed buoyancy modules make deep-sea cable configuration more complex and, moreover, their structural properties, such as structural tension and mass, are axially-changing. Thus structural motion response and its spatial-temporal evolutions become more complicated, which brings serious challenges to structural safety. In this study, a novel structural configuration, i.e. the double-stepped cable, is considered, and the dynamic governing equations of deep-water cable with distributed buoyancy modules are developed, principally based on the particular fluid-solid interaction characteristics and its coupling representation of the loadings, along with the experimental observations and verifications using our experimental water tank. The numerical simulations of the double-stepped cable dynamic response are carried out using the modified finite element approach. The responses and its corresponding propagations of the double-stepped cables, in terms of structural displacement and tensions along cable length, under environmental loadings and top-end excitations are comprehensively examined. In addition, the evolutions of displacement amplitudes and wavelengths of this kind of structure with axially-varying tension are explained based on the WKB theory. Our results show that the response does not change monotonously as it propagates along the cable length, and a local peak value may appear in the region with lower tension. Owing to the distributed buoyancy modules, along with axially-varying and discontinuous structural properties, the response spatial-temporal evolutions becomes more variant. There are mixed effects coming from both standing wave and traveling wave. It is also found that structural tensions not only affect the response amplitude significantly, also cause changes of wavelength during the process of response propagation.

     

/

返回文章
返回