基于图像处理的异重流与系泊结构物作用模型试验研究

Density currents widely exist near the estuaries of rivers, with high speed and strong destructive power, bringing considerable difficulties to the construction operations of offshore projects. In order to study the motion response of moored structures under the action of density currents, based on image processing technology, the sluice-opening type density current model test method is adopted, taking the density current and the structure as the research objects. The image processing technology is used to process the pictures of the structure's motion taken by a high-speed camera, thus obtaining the time-history curve of the structure's motion. The influences of density currents with different density ratios on the structure's motion and the influences of density currents with the same density ratio on the motions of structures at different depths are compared and discussed. The research results show that: the structure's motion is greatly affected by the density of the density current, and the motion amplitude of the structure increases with the increase of the density. The structure in the non-mixing layer of high-density fluid will produce a large clockwise rotation and a positive x-direction offset under the action of the density current; the square column at a higher position is dominated by fresh water and will produce a counterclockwise rotation and a negative x-direction offset. The square column located in the area where salt water and fresh water mix violently will not produce an offset in a single direction, but fluctuates near the equilibrium position.

异重流广泛存在于江河入海口附近,速度快、破坏力强,给近海工程的施工作业带来不小的难度。为了研究系泊结构物在异重流作用下的运动响应,基于图像处理技术,采用开闸式异重流模型试验方法,将异重流和结构物作为研究对象。利用图像处理技术处理由高速摄像机拍摄的结构物运动图片,从而获得结构物运动的时历曲线。对比讨论了不同密度比的异重流对结构物运动的影响,同一密度比的异重流对处于不同深度结构物运动的影响。研究结果表明:结构物运动受异重流密度的影响较大,结构物的运动幅值随着密度的增大而增大。处于高密度流体非混合层的结构物受到异重流的作用会产生大幅度的顺时针旋转和正x方向偏移;位置较高的方柱受到淡水的主导作用,会产生逆时针旋转和负x方向偏移。位于盐水与淡水剧烈混合区域的方柱并不会产生单一方向的偏移,而是在平衡位置附近波动。