带副叶片混流式水轮机转轮内部空化流场数值模拟

发布时间：2018-07-04 23:20

本文选题：混流式水轮机 + 计算流体力学　；参考：《昆明理工大学》2014年硕士论文

【摘要】：我国水资源居世界首位,开发利用水资源一直是我国的重大课题。在“优先发展水电”的方针背景下,我国水电建设发展迅速,水轮机朝着大容量、高水头、高比转速方面发展,对水力机组的设计、制造和科学研究也提出了新的要求。影响水轮机机组性能的三项指标为效率、稳定性和空化性能。目前,水轮机的效率最高可达95%,而空化问题历来是水力机械领域的难题之一,水轮机运行的不稳定性也随着机组水头和容量的提高而逐渐显现出来。在水轮机运行的过程中,空化会使其过流部件产生空蚀破坏,从而产生噪声和振动,严重影响机组的效率和运行的稳定性。因此,水轮机的空化空蚀问题成为水轮机领域中人们非常关心的基本问题之一。转轮是水轮机的核心过流部件,其对水轮机机组的性能起着决定性的作用,因此,对水轮机转轮空化问题的研究更应值得关注,也是提高水轮机性能必须认真研究解决的重要课题。随着CFD的发展和计算机水平的提高,数值模拟成为研究水轮机内部流动的一种重要手段。通过低成本、短周期的数值模拟对水轮机进行分析和工程设计对于提高水轮机运行的稳定性和经济性具有重要作用。本文以计算流体力学知识为基础,以通用性CFD软件FLUENT为工具,先采用基于Reynolds平均法的RNG κ-ε两方程湍流模型模拟了带副叶片混流式水轮机转轮内部的单相三维湍流流动情况,得到该水轮机转轮在不同流量工况下的三维流场分布后,再以单相流动计算结果为计算初值,补充上混合流体无滑移两相流模型,模拟了该水轮机转轮内部的空化流动情况,得到了该型水轮机转轮在不同流量工况下的空化流场分布,可以给预测、改善水轮机空化性能提供依据,对于提高水轮机效率和稳定性、改善水轮机的综合水力性能具有重要意义。本文具体完成的工作如下： 1.根据带副叶片混流式水轮机HLA351的基本单位参数,利用实体建模工具Pro/ENGINEER软件对该水轮机转轮进行了三维几何建模,然后利用前处理工具GAMBIT对转轮的几何模型进行了网格划分、设置边界类型等操作,得到了可以用于CFD计算的物理对象。 2.利用仿真工具FLUENT对带副叶片混流式水轮机转轮进行了内部单相流场的模拟,得到了该水轮机在不同流量工况下的三维流场分布。 3.以单相流动计算的结果作为初始条件,对上述水轮机进行了内部空化流场的模拟,得到了该水轮机在不同流量工况下的空化流场分布。 4.对单相流动和空化流动的结果进行后处理,总结分析了该水轮机在不同流量工况下的空化流动。
[Abstract]:Water resources in our country occupy the first place in the world, and exploitation and utilization of water resources has been a major issue in our country. Under the background of the policy of "giving priority to the development of hydropower", the construction of hydropower in China is developing rapidly, and the turbine is developing towards the aspects of large capacity, high head and high specific speed. New requirements are put forward for the design, manufacture and scientific research of hydraulic units. The efficiency, stability and cavitation performance are the three indexes that affect the performance of the turbine unit. At present, the efficiency of turbine is up to 95%, and the cavitation problem is always one of the difficult problems in the field of hydraulic machinery. The instability of turbine operation gradually appears with the increase of water head and capacity of turbine. In the process of turbine operation cavitation will lead to cavitation damage of its overflowing parts resulting in noise and vibration which seriously affects the efficiency and stability of the unit. Therefore, cavitation erosion has become one of the most important problems in turbine field. The runner is the core overflowing part of the turbine, which plays a decisive role in the performance of the turbine unit. Therefore, the study on the cavitation of the turbine runner should be paid more attention to. It is also an important subject that must be studied and solved to improve the performance of hydraulic turbine. With the development of CFD and the improvement of computer level, numerical simulation has become an important means to study the internal flow of hydraulic turbines. The analysis and engineering design of hydraulic turbine by low cost and short period numerical simulation play an important role in improving the stability and economy of turbine operation. Based on the knowledge of computational fluid mechanics and using CFD software fluent as a tool, the turbulent model of RNG 魏-蔚 two-equation turbulence based on Reynolds averaging method is used to simulate the single-phase three-dimensional turbulent flow in the runner of Francis turbine with auxiliary blades. After the three-dimensional flow field distribution of the turbine runner under different flow conditions is obtained, the cavitation flow inside the turbine runner is simulated by using the calculation results of single-phase flow as the initial value and supplementing the non-slip two-phase flow model of the upper mixed fluid. The cavitation flow field distribution of the turbine runner under different flow conditions is obtained, which can provide the basis for predicting and improving the cavitation performance of the turbine, and can improve the efficiency and stability of the turbine. It is of great significance to improve the comprehensive hydraulic performance of hydraulic turbines. The work accomplished in this paper is as follows: 1. According to the basic unit parameters of HLA351 of Francis turbine with auxiliary blades, the 3D geometric model of the turbine runner is modeled by using the solid modeling tool Pro-ENGINEER, and then the geometric model of the runner is meshed by the pre-processing tool gambit. Set the boundary type and other operations, get a CFD can be used to calculate the physical object. 2. 2. The simulation tool fluent is used to simulate the internal single-phase flow field of Francis turbine runner with auxiliary vane, and the three-dimensional flow field distribution of the turbine under different flow conditions is obtained. Taking the results of single-phase flow calculation as initial conditions, the cavitation flow field of the turbine is simulated, and the cavitation flow field distribution of the turbine under different flow conditions is obtained. The results of single phase flow and cavitation flow are processed, and the cavitation flow of the turbine under different flow conditions is summarized and analyzed.
【学位授予单位】：昆明理工大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TK733.1

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