双丁坝水流特性的水槽试验和数值模拟研究

发布时间：2018-12-31 17:31

【摘要】：丁坝是河道整治工程、海岸防护工程和防洪工程中常见的水工建筑物,研究丁坝附近的水流特性不仅具有重要的水力学研究价值,而且对丁坝尺寸的确定、坝头结构的优化和丁坝间距的布置等都有实际的指导意义。本文首先对近年来丁坝附近水流结构的研究现状进行了简要的回顾和评述,在结合前人研究成果的基础上,利用物理模型试验和数值模拟计算的方法,从理论上对双丁坝附近水流特性进行了更深入的研究。物理模型试验部分,在水槽中采用不同流量、不同水位条件下进行了双丁坝附近水流特性的试验,重点研究了双丁坝附近的流场分布和沿程水面线的变化规律以及不同流量、不同水位对双丁坝附近水流特性的影响,试验结果表明:(1)双丁坝对丁坝附近水流结构起到了很好地调整作用,水流的流向在丁坝的坝头前发生明显偏转,在丁坝附近形成了大小不同的漩涡,并在丁坝坝田区域形成了回流区。(2)在第一座丁坝的上游出现了明显的壅水现象,丁坝上游水位抬高,流速减小;水流绕过坝后出现跌水现象,至第二座丁坝附近,水位一直降低;在远离第二座丁坝下游一段距离之后,水位缓缓回升。(3)第一座丁坝的高流速区分布在坝头,第二座丁坝的高流速区偏向主槽中间分布,二者的共同作用使水流流速发生重分布。(4)当水位一定时,随着流量的增大,第一座丁坝坝头区域的高流速区逐渐向丁坝上游移动,但在第二座丁坝附近的水流流态逐渐发生紊乱。(5)当流量一定时,随着水位的增高,第一座丁坝坝头区域的高流速区逐渐向丁坝下游移动,但在第二座丁坝附近的水流流态反而更加平稳。数值模拟计算部分,利用MIKE3对双丁坝附近的流场分布和水位变化进行了数值模拟,并用物理试验结果对模拟结果进行了验证,验证结果拟合较好,证明了所建立的MIKE3数值模型用于分析双丁坝附近的水流特性是可行的。在此基础上,用数值模型分别模拟了不同工况下双丁坝附近的三维水流特性,模拟结果表明:(1)在x方向上,在靠近主槽中间都会形成大范围的高流速区,高流速区范围在垂向上表现为近底层最小、中层次之、近表层最大。(2)在y方向上,流速远小于x方向上的流速,在丁坝坝头附近都会形成流速相对较大的区域,该区域的范围在近表层、中层和近底层的分布变化基本一致。(3)在z方向上,流速更小,在第一座丁坝坝头附近形成较小范围的流速相对较大的区域,该区域在水流的近表层、中层和近底层都有分布;而在第二座丁坝的坝头附近形成的流速相对较大的区域只在近表层和中层出现。
[Abstract]:Spur dike is a common hydraulic structure in river regulation, coastal protection and flood control projects. The study of the characteristics of the water flow near the spur dike is not only of great value in hydraulic research, but also of determining the size of the spur dike. The optimization of dam head structure and the arrangement of dike spacing are of practical significance. In this paper, the current situation of the research on the flow structure near the spur dike in recent years is reviewed and reviewed briefly in this paper. Based on the previous research results, the physical model test and numerical simulation method are used. In this paper, the characteristics of water flow near double spur dams are studied theoretically. In the part of physical model test, the characteristics of water flow around double spur dam are tested with different discharge and different water level in the flume. The distribution of flow field, the variation law of water surface line along the path and the different flow rate are mainly studied. The experimental results show that: (1) the water flow structure near the spur dike is well adjusted, and the flow direction is obviously deflected in front of the dike head. A swirl of different sizes is formed near the spur dike, and a return zone is formed in the dike field. (2) the backwater phenomenon appears in the upstream of the first spur dike, the water level is raised and the velocity of velocity is decreased in the upstream of the spur dike; After the water flows around the dam, the phenomenon of falling water appears, and the water level decreases all the time near the second spur dam. After a distance from the downstream of the second spur dike, the water level rises slowly. (3) the high velocity zone of the first spur dike is distributed in the head of the dam, and the high velocity zone of the second spur dike is distributed in the middle of the main channel. The combined action of the two causes the redistribution of the flow velocity. (4) when the water level is fixed, the high velocity area of the first dike head region moves gradually upstream with the increase of the discharge. However, the flow pattern in the vicinity of the second spur dike is gradually disordered. (5) with the increase of the water level, the high velocity zone of the first spur dike is gradually moving to the lower reaches of the spur dike when the discharge is constant. But the flow around the second spur is more stable. In the part of numerical simulation, MIKE3 is used to simulate the distribution of flow field and the change of water level in the vicinity of double spur dam. The simulation results are verified by physical test results, and the results are well fitted. It is proved that the established MIKE3 numerical model is feasible to analyze the flow characteristics near double spur dams. On the basis of this, numerical models are used to simulate the three-dimensional flow characteristics in the vicinity of double spur dams under different working conditions. The simulation results show that: (1) in the x direction and near the middle of the main channel, a large range of high velocity regions will be formed. The range of high velocity in vertical direction is the minimum near bottom layer, the lowest in middle layer, and the largest near surface layer. (2) in y direction, the velocity of velocity is far less than that in x direction, and a relatively large velocity area will be formed near the dike head. The distribution of the area is basically the same in the near surface, the middle layer and the near bottom layer. (3) in z direction, the velocity of velocity is smaller, and a relatively large area is formed near the head of the first spur dam. The area is distributed in the near surface layer, middle layer and near bottom layer of water flow. However, the relatively large velocities formed near the head of the second spur dike appear only in the near surface layer and the middle layer.
【学位授予单位】：上海海洋大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TV863;TV131.6

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