【摘要】：丁壩是河道整治工程、海岸防護工程和防洪工程中常見的水工建筑物,研究丁壩附近的水流特性不僅具有重要的水力學研究價值,而且對丁壩尺寸的確定、壩頭結構的優(yōu)化和丁壩間距的布置等都有實際的指導意義。本文首先對近年來丁壩附近水流結構的研究現(xiàn)狀進行了簡要的回顧和評述,在結合前人研究成果的基礎上,利用物理模型試驗和數(shù)值模擬計算的方法,從理論上對雙丁壩附近水流特性進行了更深入的研究。物理模型試驗部分,在水槽中采用不同流量、不同水位條件下進行了雙丁壩附近水流特性的試驗,重點研究了雙丁壩附近的流場分布和沿程水面線的變化規(guī)律以及不同流量、不同水位對雙丁壩附近水流特性的影響,試驗結果表明:(1)雙丁壩對丁壩附近水流結構起到了很好地調整作用,水流的流向在丁壩的壩頭前發(fā)生明顯偏轉,在丁壩附近形成了大小不同的漩渦,并在丁壩壩田區(qū)域形成了回流區(qū)。(2)在第一座丁壩的上游出現(xiàn)了明顯的壅水現(xiàn)象,丁壩上游水位抬高,流速減小;水流繞過壩后出現(xiàn)跌水現(xiàn)象,至第二座丁壩附近,水位一直降低;在遠離第二座丁壩下游一段距離之后,水位緩緩回升。(3)第一座丁壩的高流速區(qū)分布在壩頭,第二座丁壩的高流速區(qū)偏向主槽中間分布,二者的共同作用使水流流速發(fā)生重分布。(4)當水位一定時,隨著流量的增大,第一座丁壩壩頭區(qū)域的高流速區(qū)逐漸向丁壩上游移動,但在第二座丁壩附近的水流流態(tài)逐漸發(fā)生紊亂。(5)當流量一定時,隨著水位的增高,第一座丁壩壩頭區(qū)域的高流速區(qū)逐漸向丁壩下游移動,但在第二座丁壩附近的水流流態(tài)反而更加平穩(wěn)。數(shù)值模擬計算部分,利用MIKE3對雙丁壩附近的流場分布和水位變化進行了數(shù)值模擬,并用物理試驗結果對模擬結果進行了驗證,驗證結果擬合較好,證明了所建立的MIKE3數(shù)值模型用于分析雙丁壩附近的水流特性是可行的。在此基礎上,用數(shù)值模型分別模擬了不同工況下雙丁壩附近的三維水流特性,模擬結果表明:(1)在x方向上,在靠近主槽中間都會形成大范圍的高流速區(qū),高流速區(qū)范圍在垂向上表現(xiàn)為近底層最小、中層次之、近表層最大。(2)在y方向上,流速遠小于x方向上的流速,在丁壩壩頭附近都會形成流速相對較大的區(qū)域,該區(qū)域的范圍在近表層、中層和近底層的分布變化基本一致。(3)在z方向上,流速更小,在第一座丁壩壩頭附近形成較小范圍的流速相對較大的區(qū)域,該區(qū)域在水流的近表層、中層和近底層都有分布;而在第二座丁壩的壩頭附近形成的流速相對較大的區(qū)域只在近表層和中層出現(xiàn)。
[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.
【學位授予單位】：上海海洋大學
【學位級別】：碩士
【學位授予年份】：2015
【分類號】：TV863;TV131.6

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