孤立波与淹没平板相互作用的三维波面和水动力实验研究
AN EXPERIMENTAL STUDY OF 3-D WAVE SURFACE AND HYDRODYNAMIC LOADS FOR INTERACTION BETWEEN SOLITARY WAVE AND SUBMERGED HORIZONTAL PLATE
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摘要: 在波浪水池中进行了孤立波作用下有限长度和有限宽度淹没平板的三维模型水池实验. 首次应用多目视觉立体重构技术测量局部三维自由表面变形, 该系统的有效测量水平范围为1.7 m\times 1.6 m. 用4个三分力测力传感器组成水下测力系统, 在不影响波面的情况下测量孤立波对平板的作用力和力矩. 针对波浪不破碎的情况, 选择0.4 m水深和0.16 m波高的来波条件, 平板淹没深度为0.1 m. 实验结果表明, 孤立波经过淹没平板时自由面有明显的三维变形, 导致孤立波波幅的时空变化. 波幅在平板尾缘中心线处达到最大值, 并沿展向逐渐减小. 利用多目视觉立体重构系统得到的波面变化过程与浪高仪给出定点波面时间序列相互印证, 表明建立标识码波面测量方法是有效的. 孤立波对淹没平板作用的水动力载荷变化分为6个典型阶段, 并与利用波面三维重构得到的波面测量标识码并讨论. 基于多目视觉立体重构技术得到了垂向力和俯仰力矩极值点出现时的三维波面形态. 建立的多目视觉立体重构系统将为海洋工程结构物的水池物理模型实验提供新的波面测量手段.Abstract: An experiment of interaction between a solitary wave and a submerged plate with finite length and finite width is conducted in a wave basin. A new system of the multi-lens stereo reconstruction is proposed to measure the local deformation of the free surface in the horizontal area of 1.7 m\times 1.6 m in the experiment. A set of underwater force measuring system consisted of four force balances is designed to obtain the wave loads on the submerged plate, without the interference on the surface elevation measurement. A solitary wave is generated in a wave basin of uniform water depth. The wave amplitude is 0.16 m and the still water depth is 0.4 m. The submerged depth of the horizontal plate is 0.1 m. No wave breaking occurs during the wave propagation. The three-dimensional deformations of the free surface elevation lead to the spatial and temporal variation of the solitary wave amplitude. It is found that, for the case of the present wave condition and the submerged plate, the surface elevation reaches the highest at the centerline of the plate near its trailing edge, and decreases along the span direction. The time series of the surface elevation measured by the multi-lens stereo reconstruction method agree well with the wave elevations measured by the wave gauges, which validates the new wave surface measurement system. The loading processes of the horizontal force, vertical force and the pitch moment are proposed as 6 typical phases in which the characteristics of the measured wave surface elevation are discussed. The wave surfaces measured by the multi-lens stereo reconstruction method are given at the corresponding time as the peaks of the vertical force and the pitch moment occurs. The multi-lens stereo reconstruction method could be used to measure the wave field for physical model experiments in a wave basin as a new tool.