摘要
在水电工程建设中,经常遇到泄水建筑物过流能力、体型优化及枢纽下游消能防冲等问题,解决这些问题的传统方法通常是借助物理模型试验;近些年来,随着计算机性能不断的提升和计算流体动力学的快速发展,使得数值模拟方法可以部分或全部的应用于水工建筑物泄流问题的研究,这不仅为工程师提供了泄水建筑物内部水流流动的完整信息,而且还较大程度的解放了人力,节省了财力和时间。数学模型和物理模型正日益紧密结合,成为解决水利工程泄流问题的重要手段。
本文以白龙江九龙峡水电站工程为研究对象,通过水工整体模型试验和FLUENT软件对九龙峡水电站工程泄流能力、建筑物中的水流流动信息、建筑物体型优化及枢纽下游消能防冲等问题进行了试验研究及数值模拟计算。
九龙峡水电站水工模型是按照重力相似准则设计,根据设计单位提供的基本资料制作完成。在此基础上,首先对原设计方案进行了放水试验,发现原设计方案存在诸多问题:例如泄水建筑物体型布置不合理,下泄水流冲击右岸坡等,并针对存在的问题进行了多次修改和优化完善,确定了九龙峡水电站首部枢纽的优化布置形式和体型。
利用FLUENT软件,建立了数值模拟区域,采用非结构化网格和隐式算法,以标准的k—ε湍流模型封闭Reynods方程,采用VOF法追踪自由水面,对九龙峡水电站溢流堰、底孔的水流流场按定常流动进行了三维数值模拟。结果表明:溢流堰、底孔的泄流能力、水面线、压力分布和流速分布等计算结果与模型试验结果吻合良好。
In hydropower construction, some issues are often encountered such as the conveyance capacity of discharge structure, shape optimization and energy dissipation and erosion control of hydro-junction downstream and so on.The physical model test is usually used to solve these problems in traditional methods .In recently years, with the continuous improvement of computer performance and the rapid development of computational fluid dynamics,the numerical simulation method can be used in the study of part or all of the discharge of hydraulic structures, which not only provides complete flowing information of internal water flow of hydraulic structures to engineers, but also liberates human in a greater extent and saves finance and time. Mathematical models and physical models are increasingly and closely integrated as an important means in solving the problem of discharge of hydraulic engineering.
In this paper, Bailongjiang JiuLongXia hydropower station project is used as a research object. The discharge capacity, flowing information of internal water flow of hydraulic structures, shape optimization of hydraulic structures and energy dissipation and erosion control of hub downstream etc. of JiuLongXia hydropower station were studied through hydraulic model test, and were simulated by software FLUENT.
The hydraulic model of JiuLongXia hydropower station is based on gravity similar theory, and was build in accordance with the design data of design department. On this basis, the flow discharge test was carried out for the original design scheme at first. There are many problems, such as: the layout of discharge structure is unreasonable, the right bank is impacted by discharged water etc. and a number of modifications are made and optimizations for the problems, the optimal layout and somatotype of head of pivot of JiuLongXia hydropower station were conformed.
By means of software FLUENT, establishing numerical simulation region, using unstructured grids and implicit method and in addtion,the k—εturbulent model is used to close Reynods equations, volume of fluid(VOF) method is used to track the free water surface, the flow state of the overflow weir and bottom outlet of Jiulongxia hydropower station is simulated in the method of three-dimensional numerical simulation according to the steady flow. The conclusion shows that the calculation results that the overflow weir discharge capacity and the water surface profile and the pressure distribution and velocity distribution are in good compliance with the measured data.
引文
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