弯道水流特性试验研究及数值模拟

发布时间：2018-06-03 06:14

本文选题：U形弯道 + 水流特性　；参考：《上海海洋大学》2014年硕士论文

【摘要】：在河流、河口及港口地带，几乎都存在着弯道，研究弯道水流的特性对河流工程的建设与运行、港口的建设、河道的防洪设计、桥梁的规划设计、流域的长远规划以及改善河道的通航运行等都具有极其重要的意义。本文利用物理模型试验和数值模拟计算结合的方法，对U形弯道水流特性进行了研究。物理模型试验方面，，通过自动水位测量系统及流速测量系统研究U形水槽弯道段的水位及流速变化情况；数值模拟计算方面，运用MIKE3软件并结合物理模型试验，建立一个与物理模型相同尺寸的三维水流数学模型，用物理模型试验所测得的水位和流速资料对模型进行验证，模型计算的水位和流速与试验结果拟合较好，说明该三维水流数值模型可以用于弯道水流特性的数值模拟研究。结果表明：（1）水流由直段进入弯道后，凹岸处的水位抬升，凸岸处的水位下降，凹凸岸间的水位差值呈现出先增大后减小的趋势。流量的增加使得凹凸岸间的水位差值均增大；水位的抬升使得凹凸岸间的水位差值均减小。（2）在U形弯道内，流速进行了重新分布，主流线由凸岸逐渐偏向凹岸。（3）在底层，水流在流经U形弯道时其主流向偏向凸岸；在中层，水流在流经U形弯道时其主流向与边界趋于平行；在表层，水流在流经U形弯道时其主流向偏向凹岸。（4）x、y方向上的流速在垂向上均表现为底层往表层依次增大。z方向上的流速在垂向上表现为：在凸岸处中层z方向上的流速大于底层及表层z方向上的流速；而在凹岸处中层z方向上的流速小于底层及表层z方向上的流速。（5）在出口处水位不变的情况下，随着流量的增加，弯道内底层、中层和表层处凹凸岸间x、y、z方向上的流速差值均有所增大。（6）在进口处流量不变的情况下，随着水位的抬升，弯道内底层、中层和表层处凹凸岸间x、y方向上的流速差值均有所减小；底层和表层处凹凸岸间z方向上的流速差值减小，中层处凹凸岸间z方向上的流速差值则增大。
[Abstract]:It is very important to study the characteristics of bend water flow to the construction and operation of river engineering , the construction of port , the flood control design of the river , the planning and design of the bridge , the long - term planning of the river basin and the improvement of the navigable operation of the river course .

In this paper , the characteristics of water flow in U - shaped channel are studied by means of physical model test and numerical simulation calculation . In physical model test , the water level and velocity change of U - shaped channel curve section are studied by automatic water level measuring system and flow rate measuring system .
In terms of numerical simulation , using MIKE3 software and physical model test , a mathematical model of three - dimensional water flow with the same size as the physical model is established , and the model is verified by the physical model test . The water level and the flow velocity of the model are fitted well with the test results . The numerical simulation of the three - dimensional water flow numerical model can be used for the curve flow characteristics .

The results show that :

( 1 ) after the water flow enters the curve by the straight section , the water level at the concave bank rises , the water level at the convex bank decreases , and the difference of the water level between the concave and convex banks shows the trend which is decreased firstly , and the difference of the water level between the concave - convex banks is increased ;
the rise of the water level causes the difference in the water level between the relief banks to be reduced .

( 2 ) In the U - shaped curve , the flow velocity is redistributed , and the main flow line is gradually shifted to the concave bank by the convex bank .

( 3 ) at the bottom layer , the main flow of water flows towards the convex bank when flowing through the U - shaped curve ;
In the middle layer , the main flow is parallel to the boundary when flowing through the U - shaped curve ;
In the surface layer , the water flows toward the concave bank mainly when flowing through the U - shaped curve .

( 4 ) the flow velocity in the x and y directions is shown as the bottom layer to the surface layer in the vertical direction , and the flow velocity in the z direction is shown as follows : the flow velocity in the middle layer z direction at the convex bank is larger than the flow velocity in the direction of the bottom layer and the surface layer z ;
and the flow velocity in the middle layer z direction at the concave bank is smaller than the flow velocity in the direction of the bottom layer and the surface layer z .

( 5 ) With the change of the water level at the outlet , the difference of flow velocity in the x , y and z directions at the bottom layer , the middle layer and the surface layer of the curve increases with the increase of the flow rate .

( 6 ) in the case where the flow rate is constant at the inlet , the difference in flow velocity in the x and y directions of the bottom layer , the middle layer and the surface layer of the curve is reduced along with the rise of the water level ;
the difference of flow velocity in the z - direction between the bottom layer and the surface layer is reduced , and the difference of the flow velocity in the z - direction between the concave - convex banks in the middle layer is increased .
【学位授予单位】：上海海洋大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TV143

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