水电施工截流模型试验及其水力特性数值模拟研究

发布时间：2018-05-28 13:22

本文选题：模型试验 + 截流水力学　；参考：《武汉大学》2014年博士论文

【摘要】：我国水电工程建设的高速发展,为大江大河的截流积累了丰富的工程和理论经验。相比于河道截流的物理模型试验,数值模拟技术在很多方面具有不可比拟的优势。特别是ANSYS Workbench的新开发平台,兼容了包括流体和流场在内的很多模块。本文根据实际工程进行了水电工程截流模型试验,提出了基于ANSYS的截流龙口水力特性数值模拟方法。根据模型试验规程的要求,以实际工程的截流为依据,进行截流模型试验研究。从模型的比尺确定、河道模型的设计与制作、河道模型的率定,到试验过程设计、截流试验准备,进行了较详细的论述。然后按试验工况详细整理了截流试验成果,并对试验结果进行了分析。研究发现,截流难度随截流流量的增大而增大,随分流能力的增强而降低,随下游尾水位的抬高而降低。在模型试验中,引入VDMS监测流场流态及表面流速分布,对截流控制性参数进行模拟,提出了分流因数的面积积分方法,通过统计分析来研究龙口宽度、截流流量大小、导流洞进口分流条件、下游电站蓄水位及隧洞流态等因素与导流洞分流能力的关系。在截流试验的基础上,提出了截流河道水流及其龙口水力学参数的数值模拟方法,并基于ANSYS建立了具有自由表面的水流流动分析模型。本文以APDL模块建立几何模型,以ICEM CFD模块建立流场模型,在CFX-Pre模块中设置流场分析类型、定义边界条件、加载初始条件,通过CFX-Solver Manager实现流场分析计算,并采用CFD-Post模块进行数值模拟,详细介绍了河道流场数值模拟的过程。仿真后处理模块可以实现流速、水深等水力学要素的可视化表达。通过与光滑壁面流场的对比分析发现,在进口附近的水面线位置较低,水流紊动强度较弱。在进行水电施工截流龙口水力学参数的数值模拟时,将非恒定流离散化为恒定流进行处理。根据模型试验工况一的上下游水流参数(流量、水位、流速等),进行了四种龙口宽度的截流龙口水力学参数的数值模拟。结果表明,通过调用ANSYS Workbench的后处理模块,利用isoface和polyline求解截流期间不同龙口宽度的河段水面线高程。利用isoface和contour配合可以很好地解决龙口范围的流速分布及大小问题。采用纵横断面及水平剖面切割的方法去拾取、观察龙口范围内的流场。特别是通过使用等值面isosurface设置流速选项,利用水平面,结合等值线云图,取不同的流速值,观察流场中的位置,能够形象直观的描绘龙口流场内的流速分布情况。最后,通过对比分析戗堤宽度对截流龙口的流速、水面变化等的影响,发现宽戗堤较窄戗堤,可以改善水流对戗堤端头的冲刷,同时也带来了龙口轴线下游流速增加的问题。本文通过对河道截流的物理模型试验和数值模拟试验的对比研究,说明利用ANSYS Workbench进行截流水力特性的数值模拟是可行的,为水电施工截流的数值模拟提供了一种新的思路。
[Abstract]:The rapid development of China's hydropower project construction has accumulated rich engineering and theoretical experience for the river closure of the big river. Compared with the physical model test of the river interception, the numerical simulation technology has unparalleled advantages in many aspects. Especially, the new development platform of ANSYS Workbench is compatible with many models including fluid and flow field. In this paper, a river closure model test is carried out according to the actual project. A numerical simulation method for hydraulic characteristics of closure closure is proposed based on ANSYS.
According to the requirements of the model test regulation, the interception model test is carried out on the basis of the actual project closure. From the scale determination of the model, the design and production of the river model, the rate of the river model, the design of the test process and the preparation of the interception test, a detailed discussion is made. Then the interception test is arranged in detail according to the test conditions. It is found that the difficulty of the intercepting flow increases with the increase of the flow rate, and decreases with the increase of the shunt capacity, and decreases with the rise of the downstream tail water level. In the model test, the flow pattern and surface velocity distribution of the flow field are monitored by VDMS, and the flow control parameters are simulated and the shunt factor is proposed. The area integral method is used to study the relationship between the width of the dragon mouth, the flow rate, the inlet diversion condition of the diversion tunnel, the water position of the downstream power station and the flow state of the tunnel, and the diversion capacity of the diversion tunnel.
On the basis of the intercepting test, the numerical simulation method of the water flow and the hydraulic parameters of the dragon mouth is put forward. Based on the ANSYS, a flow analysis model with free surface is established. In this paper, the geometric model is established by the APDL module, the flow field model is set up with the ICEM CFD module, the flow field analysis type is set up in the CFX-Pre module, and the definition of the flow field is defined. The boundary condition is loaded with initial conditions. The flow field analysis is calculated by CFX-Solver Manager, and the numerical simulation of the flow field is introduced in detail by using the CFD-Post module. The simulation processing module can realize the visualization of flow velocity, water depth and other hydraulics elements. It is found that the position of the water surface near the inlet is low, and the turbulence intensity of the flow is weak.
In the numerical simulation of the hydraulic parameters of the hydroelectric construction closure, the unsteady flow is dispersed into a constant flow. The numerical simulation of the hydraulic parameters of four kinds of dragon mouth opening is carried out according to the upstream and downstream flow parameters (flow, water level, velocity and so on) of the model test conditions. The results show that the ANSYS Wo is called by the call. The post processing module of rkbench uses isoface and polyline to solve the water surface elevation of the river section with different length of the dragon mouth during the intercepting. Using the combination of isoface and contour can solve the problem of the velocity distribution and size of the dragon mouth well. The flow field in the range of the dragon mouth is observed by the method of vertical and horizontal section and horizontal section cutting. By using the equivalent surface isosurface to set the flow rate option, using the horizontal surface, combining the contour line with the contour map, taking the different velocity values and observing the position in the flow field, the velocity distribution in the flow field of the dragon mouth can be depicted intuitively. Finally, the effect of the width of the dike on the flow velocity and the change of the water surface in the closure is compared and analyzed. A narrow embankment can improve the scour of the current to the end of the embankment and increase the flow velocity at the downstream of the Longkou axis.
By comparing the physical model test and the numerical simulation test of the river interception, this paper shows that it is feasible to use the ANSYS Workbench to simulate the hydraulic characteristics of the current interception, and provides a new idea for the numerical simulation of the hydroelectric construction interception.
【学位授予单位】：武汉大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：TV135.5;TV551.2

【参考文献】