阶梯溢流坝和宽尾墩及消力池组合消能的水流数值模拟研究

采用两相流模型,辅以Realizable k湍流模型,来模拟阶梯溢流坝和消力池组合以及阶梯溢流坝、宽尾墩和消力池组合两种联合消能工的水力特性,获得了流速场、压强场、紊动动能及紊动动能耗散率等物理参量的分布。网格划分采用了分区域划分:模型中任何形状不规则的复杂部分采用非结构网格划分,对形状规则的部分则采用了结构网格划分,并根据流动梯度的大小安排网格的疏密程度。采用有限体积法对控制方程进行离散。采用了VOF法处理自由水面,使用PISO算法求解速度与压力的耦连方程组。比较分析了两种消能工在速度场、压强场、紊动动能及紊动动能耗散率的差异。研究结果表明:受宽尾墩的影响,坝面及消力池中的流速均小于无宽尾墩的情况,而台阶坝面的压强明显高于无宽尾墩的情况;在消力池中紊动动能及其耗散率均大于无宽尾墩的情况。可见,阶梯溢流坝、宽尾墩和消力池组合消能工的消能优于无宽尾墩的情况。

Numerical simulation of flow on stepped spillway combined with flaring gate piers and stilling basin

In this paper,a two-phase flow model combined with the Realizable turbulence model was used to simulate hydraulic characteristics of two-type dissipaters: the stepped spillway combined with stilling pool and the stepped spillway combined with wide tailing pier and stilling pool.The distributions of physical parameters,such as velocity field,pressure field,turbulence kinetic energy and turbulence dissipation rate were obtained in the flow field.The grid was generated by using the regional division method,the unstructured grids used for the irregular and complex parts and the structured grids for the regular and simple parts,and the grid density was arranged according to the flow gradient size.The finite volume method was adopted to discretized the control equations;and the VOF method was adopted to deal with the free water surface;and the PISO algorithm was used to solve the velocity and pressure coupling equations.A comparative analysis of the two energy-dissipators in the velocity field,pressure field,turbulence kinetic energy and turbulence kinetic energy dissipation rate shows that under the influence of flaring gate piers,the flow velocities in the regions of dam and stilling pool are less than those without flaring piers,and the pressure on the stepped-dam face is obviously higher than that without wide tailing pier situation;in stilling pool turbulent kinetic energy and dissipation rate are larger than those without flaring gate pier.Therefore dissipation of the stepped spillway overflow together with wide tailing pier and stilling pool jointing energy dissipator is better than that without flaring gate pier situation.