桩柱式围网养殖系统水动力特性研究

发布时间：2018-05-25 19:13

本文选题：水产养殖 + 桩柱式围网　；参考：《浙江海洋大学》2017年硕士论文

【摘要】：桩柱式围网养殖是一种新兴发展的生态型养殖模式。由于该种养殖模式尚处于起步阶段,在台风等浪高、流急的恶劣环境下,存在因结构设计与施工技术尚不成熟引起的设施安全隐患等诸多关键技术问题有待解决。因此本文针对桩柱式围网养殖系统在波浪和水流作用下的水动力特性进行了研究。本文基于集中质量点法对网衣进行了合理的简化,受力分析,并建立了网衣的运动响应数学模型。此外,通过物理验证性试验对此数学模型进行了验证,比较模拟结果和试验结果发现吻合较好。利用建立的数值模拟方法研究了桩柱式围网网片在波浪作用下的水动力特性,分析了波高、波向、网片尺寸、固定方式、纲绳直径和纲绳网格大小对围网网片网线张力分布、结节偏移和系缚点受力等的影响。研究结果发现:波高的变化对网片首尾系缚点受力影响较大而对中间系缚点影响相对较小。波向30°~70°时为网线最大张力和系缚点受力的主要增加段。通过系缚点间距与网片横宽比,可判断网线最大张力发生的部位。增加系缚点的数量有利于降低所有系缚点的受力,但当超过临界系缚点数量(为4~5个)时,网线的最大受力和最大偏移不再显著下降。当纲绳直径小于4mm时,网片内部张力主要由网线承担,当纲绳直径大于4mm时,纲绳转变为张力的主要承担者,而纲绳和网线的运动不再显著减小。采用菱形纲绳时网线的最大张力比采用相当大小的矩形纲绳时网线的最大张力稍小,发现菱形纲绳有传导力的作用而矩形纲绳隔绝了内部网线张力的传导。矩形纲绳的首尾系缚点受力比菱形纲绳小,但是矩形纲绳的中间系缚点受力比菱形纲绳更大。除了考虑波浪的作用,本文同样利用数值模拟对桩柱式围网网片在水流作用下的水动力特性进行了研究分析。分析发现:在水流中网片各部位的受力和变形比在波浪中小。水流中有较多水动力特性规律几乎为波浪中的对称形式,但属于在水流中独特水动力特性的也不少,如网线最大张力和系缚点最大受力随流向的增加而增加。菱形纲绳的网片增加其纲绳网格密度不会影响其首尾系缚点的受力,而在添加纲绳的系缚点处,该系缚点的受力会增加,但同时使其周围的系缚点受力减小。矩形纲绳有拦截力的作用,能减小首尾系缚点的受力,但会增加中间系缚点的受力,特别是在水流中,中间系缚点的受力甚至超过了首尾系缚点的受力。以及菱形纲绳与矩形纲绳上最大张力的分布等都与波浪中的大不一样。在基于局部网片的研究经验基础上,利用数值模拟对桩柱式围网养殖系统的整体水动力特性进行了研究,分析了系统代表性部位的网片荷载、纲绳张力、网片变形和桩柱合力,研究发现:系统的中间部位是主要受作用部位。一般系统拐角处的桩柱受力比边上的大。作用角度的改变对系统内部存在一定的影响,但对系统整体影响较小,而且无明显规律可循。本文研究结果可为桩柱式围网设计、制作、海上敷设、安全性能评估和围网抗风浪技术的研发等提供重要参考价值。
[Abstract]:Pile column Seine aquaculture is a newly developed ecotype culture model. Because the breeding mode is still in its infancy, many key technical problems, such as the structure design and the construction technology, are still in need to be solved. The hydrodynamic characteristics of the Seine culture system under the action of wave and water are studied. Based on the centralized mass point method, this paper makes a reasonable simplification, the force analysis, and establishes the mathematical model of the motion response of the net clothing. In addition, the mathematical model is verified by the physical verifying test, and the simulation results and the experiments are compared. The results are found to be in good agreement. The hydrodynamic characteristics of the pile column mesh mesh under the action of waves are studied by the numerical simulation method. The influence of wave height, wave direction, mesh size, fixed mode, rope diameter and rope mesh size on the tension distribution, nodular migration and tie point force are affected. Now: the change of wave height has a great influence on the force of the head and tail of the net, and the influence on the tie point is relatively small. When the wave is 30 ~70 degrees, it is the main increase section of the maximum tension and the force of the tie point. By the distance of the tie point and the width ratio of the mesh, the number of the maximum tie points can be judged to be reduced. The force of all the tie points, but when the number of the critical tie points (4~5), the maximum force and maximum offset of the wire is no longer significantly reduced. When the diameter of the class rope is less than 4mm, the internal tension of the mesh is mainly borne by the wire. When the diameter of the rope is greater than 4mm, the class rope is the main bearer of the tension, and the movement of the class rope and the wire is no longer. The maximum tension of the wire is slightly smaller than that of a rectangular line with a diamond line. It is found that the rhombus rope has the effect of conducting force and the rectangular rope isolated the conduction of the tension of the inner mesh line. The force of the first tie point of the rectangular rope is smaller than the diamond line, but the middle line of the rectangular rope is in the middle. In addition to considering the effect of wave, the hydrodynamic characteristics of pile column mesh mesh in water flow are studied and analyzed by numerical simulation. It is found that the force and deformation ratio of each part of the mesh in the flow are small and small in the wave. The symmetrical form in the wave is also a lot of unique hydrodynamic characteristics in the flow, such as the maximum tension of the wire and the maximum force of the tie point increase with the flow direction. The mesh density of the rhombus rope will not affect the force of its first tie point, and the force of the tie point at the tie point of the rope is added. Increasing, but at the same time reducing the force of the tie point around it. The rectangular rope has the effect of intercepting force to reduce the force of the first tie point, but increases the force of the intermediate tie point, especially in the flow, the force of the intermediate tie point is even more than the force of the first tie point, and the maximum tension on the diamond rope and the rectangle rope. Cloth and so on are different from the waves. Based on the research experience based on local mesh, the whole hydrodynamic characteristics of the pile column Seine aquaculture system are studied by numerical simulation. The mesh load of the representative parts of the system, the tension of the rope, the deformation of the net sheet and the combined force of the pile and column are analyzed. The research shows that the middle part of the system is the main part. The force of the pile and column at the corner of the general system is larger than that on the side. The change of the angle of action has a certain influence on the system, but it has little influence on the system, and there is no obvious rule to follow. The results of this paper can be used for the design, production, marine laying, safety performance evaluation and the anti wave technology of the fence. R & D and so on provide important reference value.
【学位授予单位】：浙江海洋大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：S967

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