三维VOF模型在台阶式溢洪道中的应用研究

发布时间：2018-12-11 01:15

【摘要】：在水利工程建设中,必须设置泄水建筑物。台阶式溢洪道是水利工程中善用的泄水建筑物,用来调节库容中不能容纳的洪水,以保证大坝安全。台阶式溢洪道不但要满足充足的泄流能力,而且在使用的过程中要保证台阶式溢洪道的安全性能,以及下泄水流与原河道之间不产生破坏性的影响。地处中国西北的高海拔寒冷地域的青海省,水电资源十分丰富。在高海拔的寒冷地区,研究台阶式溢洪道所具有的水力特性对于防止坝面的空化、空蚀有着不可磨灭的意义。本文采用VOF方法,结合RNGκ-ε双方程紊流模型和单向流体自由追踪界面对台阶式溢洪道进行了三维数值模拟研究:总结了RNGκ-ε双方程紊流模型的发展过程,介绍了数值模拟技术的应用现状,通过调整台阶式溢洪道的平面布置、台阶级数和台阶尺寸,对台阶式溢洪道的水流流态水面线流速压强和消能率等水力特性进行了分析。研究结果表明:台阶式溢洪道的水流形态划分为过渡水流流态跌落水流流态和滑行水流流态。在设置有过渡段时,水流流经过渡段后受失重影响,水面线在初始台阶骤减,之后逐渐回升。消力池段由于受消力池底板的反作用力,水面线突增,水流达到稳定状态后水面线趋于平稳;跌落水流流态时,台阶内部凹角处水流流速方向与台阶水平面形成45°角,滑行水流流态时,水体上表面的流速方向与台阶外边缘连线平行,台阶内部水流形成漩涡三角区;增大来流量后,单个台阶水平面正压值增大,正压最大值位于台阶步长0.8倍处,台阶竖直面上负压最大点易产生在台阶顶端范围内,负压范围占台阶比例的50%-65%。
[Abstract]:In the construction of water conservancy projects, drainage structures must be set up. The stepped spillway is a well-used drainage structure in water conservancy works, which is used to regulate the flood which can not be contained in the reservoir to ensure the safety of the dam. The stepped spillway should not only satisfy the sufficient discharge capacity, but also ensure the safety performance of the stepped spillway and no destructive effect between the discharge flow and the original channel. Qinghai Province, located in the cold high altitude region of northwest China, is rich in hydropower resources. In the cold area of high altitude, the study of hydraulic characteristics of stepped spillway has an indelible significance to prevent cavitation and cavitation of dam surface. In this paper, the three-dimensional numerical simulation of stepped spillway is carried out by using VOF method, combined with RNG 魏-蔚 two-equation turbulence model and unidirectional fluid free tracing interface. The development process of RNG 魏-蔚 two-path turbulence model is summarized. The application status of numerical simulation technology is introduced. By adjusting the plane arrangement, step series and step size of the stepped spillway, the flow pattern of the stepped spillway is analyzed. Water line? Velocity? Hydraulic characteristics such as pressure and energy dissipation rate are analyzed. The results show that the flow pattern of the stepped spillway is divided into transitional water flow patterns. Falling water flow and sliding water flow. When there is a transition section, the water flow is affected by weightlessness, and the water surface line decreases sharply at the initial step, and then rises gradually. Due to the reaction of the bottom plate of the stilling pool, the water surface line suddenly increases, and the water surface line tends to be stable after the flow reaches the stable state. When falling water flow, the direction of flow velocity at the concave corner of the step and the horizontal plane of the step form 45 掳angle, while the direction of velocity on the surface of the water body is parallel to the line of the outer edge of the step, and the swirl triangle area of the flow in the step is formed. After increasing the flow rate, the positive pressure of a single step increases, the maximum of the positive pressure is at 0.8 times the step length, the maximum point of negative pressure on the vertical surface of the step is easily within the top range of the step, and the negative pressure range accounts for the proportion of 50 to 65 percent of the step.
【学位授予单位】：青海大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TV135.2

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