有软壳海洋生物附着圆形柱体的涡激振动的影响研究

Experimental Studies on Vortex-Induced Vibrations of a Circular Cylinder Covered with Soft Marine Growth

摘要: 伴随着海上资源的开发，越来越多的海上设施出现。研究对水下构筑物状态的影响因素对海上设施的设计具有重要意义。随着研究的深入，海洋生物的附着对近海建筑物的水下结构物的污染受到更多的关注，其中，附着的海洋生物可以分为硬壳海洋生物和软壳海洋生物两大类。以往的研究大多是模拟硬壳海洋生物的附着对象。作为对已有研究的补充，本文的研究对象为附着有软壳海洋生物的圆柱体。通过设置对照试验，研究不同长度和间隙比的海洋软壳生物的动力响应，包括阻力和旋涡脱落特性。制作6个实验组模型的方法是在长为125 cm，宽为20 cm柔软的薄膜上在特定位置切割孔来固定宽度为1.5 cm彩带，将彩带和薄膜覆盖在直径为6 cm，长130 cm的圆柱形钢管上。考虑间隙比分别为0.5 D和0.8 D，长度分别为0.5 D、1 D和2 D (D为圆柱形钢管直径)。对照组则是由圆柱形钢管和只覆盖薄膜的圆柱形钢管组成。所有实验均在位于西澳大利亚大学结构实验室的风洞中进行。通过不同的软件记录原始数据，并使用MATLAB和EasyPlot进行数据处理。所有结果在汇总后，利用Prism绘制图表。将各实验组模型的计算结果与对照组模型的计算结果进行了比较。研究发现，用于模拟的软壳海洋生物的彩带会使模型受到更大阻力的同时也抑制涡激振动。研究拓展了海洋生物附着对圆柱结构所受阻力和涡激振动的认识。

Abstract: With the development of the technique, more and more offshore facilities appear. It is important to study the influence of various factors on the state of structures underwater for the design for the offshore facilities. With further research, the effect of marine pollution on construction has become popular. Marine pollution is manifested as organisms in the ocean clinging to underwater structures in offshore buildings and the marine organisms are divided into two main categories, hard marine and soft marine. Most of the previous studies had simulated the attachment object of hard marine. As a supplement to existing research, the object of the research was the circular cyl-inder covered with soft marine growth. The hydrodynamic responses, force and vortex shedding characteristics, of soft marine with different lengths and gap ratios are studied by setting up control experiment. The method of six models made was that cutting holes at specific positions on the 125 cm long, 20 cm wide soft film and fixing the 1.5 cm wide ribbon then covering the film with ribbon on steel circular cylinder. The diameter of the cylinder is 6 cm and the length is 130 cm. The gap ratio is 0.5 D and 0.8 D respectively and the length is 0.5 D, 1 D and 2 D respectively (D is the diameter of the steel circular cylinder). The control group consisted of a steel circular cylinder and a steel circular cylinder covered only with a film. All experiments were conducted in a wind tunnel located in the Structural Laboratory of the University of Western Australia. The raw data was recorded by different software and processed using MATLAB and EasyPlot. All the results are summarized and plotted using Gnuplot. The calculation results of each experimental group model were compared with those of the control group model. It was found that the ribbon of soft-shell Marine organisms used in the simulation subjected the model to greater drag while also suppressing vortex-induced vibration. This study expands the understanding of the drag force and vortex- induced vibration of steel cylinder covered by soft marine growth.