EI、Scopus 收录
中文核心期刊

内孤立波作用下潜深对潜体运动响应和载荷特性的影响研究

INFLUENCE OF DIVING DEPTH ON MOTION RESPONSE AND LOAD CHARACTERISTICS OF SUBMERGED BODY UNDER ACTION OF INTERNAL SOLITARY WAVE

  • 摘要: 内孤立波常发生于海洋密度跃层, 因其峰高谷深、携带能量巨大, 在传播过程中会导致跃层上下的海水流动呈现剪切状态, 并引起突发性的强流. 潜体在水下悬停时极有可能会遭遇内孤立波, 由于内孤立波的流场特性, 置于跃层上下的悬浮潜体所产生运动响应和水动力载荷变化不尽相同, 甚者会出现掉深现象. 为探究潜深对波体耦合作用的影响, 基于不可压缩N-S方程和mKdV理论, 采用速度入口造波, 结合重叠网格技术和流固耦合方法, 建立了分层流中内孤立波耦合水下潜体多自由度运动的数值模型, 通过该模型分析了不同潜深下悬浮潜体的运动响应和载荷特性. 结果表明: 在内孤立波作用下, 位于密度跃层上方和跃层中的潜体顺着波的前进方向运动, 先下沉后抬升, 位于跃层下方的潜体则会逆流持续下沉; 潜体与波面的垂向距离越小, 对其纵荡、垂荡和速度的影响越显著, 而位于密度跃层中的潜体在分界面处沿着波形运动, 其运动响应和载荷变化受影响较小; 潜体在跃层上、下流体中所受水平力的方向相反, 水平力峰值小于垂向力峰值, 且位于跃层下方的潜体一直受到低头力矩, 最终导致掉深.

     

    Abstract: Internal solitary waves frequently occur in ocean pycnocline. Because of its high crest, deep trough and huge energy, the seawater flow above and below the pycnocline will show a shear state and cause a sudden strong current. When hovering underwater, the submersible is likely to encounter internal solitary waves. Due to the flow field characteristics of internal solitary waves, the motion response and hydrodynamic load changes of the suspended submersible placed above and below the pycnocline are different, and even the phenomenon of falling deep will occur. This work aims to explore the influence of the submerged depth on the wave-body coupling based on mKdV theory and the CFD method. The velocity inlet boundary is used for wave generation. The overset grid and fluid-structure coupling methods are adopted to simulate the submerged body with multi-degree-of-freedoms. The motion response and hydrodynamic load of suspended submerged bodies at different depths are analyzed. The results show that under the action of internal solitary waves, the submerged body above and in the pycnocline move along the forward direction of the wave, sink at first and then rises, and the submerged body below the pycnocline will continue to sink against the current; The smaller the vertical distance between the submerged body and the wave surface, the more significant the influence on its surge, heave and velocity. However, the submerged body located in the pycnocline moves along the waveform at the interface, and its motion response and load changes are slightly affected; The directions of the horizontal force on the submerged body above and below the pycnocline are opposite. The peak value of the horizontal force is less than the peak value of the vertical force, and the submersible below the pycnocline always experiences a head-down moment, which eventually leads to falling deep.

     

/

返回文章
返回