非对称型汇流口数值模拟研究

发布时间：2018-03-07 01:25

本文选题：非对称型汇流口　切入点：复式断面地形　出处：《西安理工大学》2017年硕士论文　论文类型：学位论文

【摘要】：干支流相互顶托掺混使交汇口附近流场、水深、泥沙冲淤等水力因素发生变化,出现螺旋流、二次流、局部水流停滞、分离和水面凸起诸多独特复杂的水力现象,导致堤岸冲刷、泥沙局部淤积,影响污染物的扩散与运输,故交汇河段水流水力特性的研究具有重大意义。本文对干支流汇流区段水流结构进行了理论分析,建立交汇角为45°非对称型清水定床水槽,在不同的地形条件和汇流比下设定八种工况进行模型试验。运用ANSYS ICEM对水槽进行三维建模,利用FLUENT软件(选用RNG k-ε模型、QUICK格式离散、SIMPLEC算法耦合压力速度、VOF法捕捉自由表面)对交汇角为45°时两种地形下汇流比分别为1:1、1:2、1:3、1:4各工况以及交汇角度分别为30°、60°、90°的三种工况进行了模拟,分析了不同地形、不同汇流比、不同入汇角时非对称干支流交汇口水流特性规律,得出以下结论:(1)干流测压管水头沿程变化较缓,但支流汇入会造成交汇口处流速水头增大,测压管水头降低。(2)复式地形断面水流紊动强烈,水面线波动较大;受铺设地形的约束作用,水流动力轴线偏向水槽中心,分离区范围缩小。(3)汇流比1:3时水流动力轴线靠近水槽中心线,对左右岸冲刷均最小;交汇角为45°时各个断面流速变化梯度小,水流动力轴线靠近水槽中心线,对两岸冲刷最小。(4)交汇角为90°时交汇口上游壅水严重,下游流速变大,分离区范围变大,能量损耗最大。
[Abstract]:The flow field, water depth, sediment scour and silt and other hydraulic factors in the vicinity of the intersection are changed due to the mixing of the top support and the top support of the main tributaries, resulting in helical flow, secondary flow, partial water flow stagnation, separation and many unique and complex hydraulic phenomena of the water surface protruding. As a result of levee erosion, local siltation of sediment and influence on the diffusion and transportation of pollutants, it is of great significance to study the hydraulic characteristics of the flow in the intersection reach. This paper makes a theoretical analysis of the flow structure in the confluence section of the trunk and tributaries. A 45 掳unsymmetrical clear water fixed bed flume with an intersection angle of 45 掳was established. The model tests were carried out under different topographic conditions and flow concentration ratios. ANSYS ICEM was used to model the flume. Using FLUENT software (using RNG k- 蔚 model / quick scheme to discretize SIMPLEC algorithm coupling pressure velocity and VOF method to capture free surface), three kinds of confluence ratio of 1: 1 / 1 / 2 / 2: 1 / 3 / 1 / 4 and 30 掳60 掳/ 90 掳angle of intersection are used in two different terrain when the angle of intersection is 45 掳, respectively, of which the confluence ratio is 1: 1 / 1 / 2: 1 / 3 / 1 / 4 and the angle of intersection is 30 掳60 掳/ 90 掳respectively. The operating conditions are simulated. The characteristics of water flow at the intersection of asymmetric tributaries with different topography, different confluence ratios and different entrances angles are analyzed. The following conclusions are drawn: 1) the water head of the main stream pressure measuring pipe changes slowly along the path, but the flow velocity head at the junction increases when the branch flows into the channel. The water head of the pressure measuring pipe is lowered. 2) the flow of the complex topographic section is turbulent and the water surface line fluctuates greatly, and the axis of the water power is inclined to the center of the flume because of the constraint of the laid terrain. At 1: 3, the flow power axis is close to the center line of the flume, and it is the smallest to the left and right bank scour, and the gradient of the velocity of each section is small when the intersection angle is 45 掳, and the axis of the flow power is close to the central line of the flume. When the intersection angle is 90 掳, the upstream backwater is serious, the downstream velocity is larger, the separation area is larger, and the energy loss is the largest.
【学位授予单位】：西安理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TV133;TV148

【参考文献】