进口形式对平流式沉淀池水力特性影响的数值模拟

Numerical simulation for the influence of inlet type on the hydraulic characteristic in a horizontal sedimentation tank

数值求解气液两相流模型,辅以Realizable k-ε湍流模型,模拟了不同的进口形式对平流式沉淀池水力特性的影响。采用有限体积法离散流体运动的控制方程,采用压力隐式算子分裂(PISO)算法求解离散方程;利用VOF法追踪自由水面的位置。经过对模拟结果的分析发现:在平流式沉淀池的进口设计中,当进口布置在进水墙竖直方向中间位置时,可以使回流区长度减小,能够提高初沉池的运行效率。在条件允许的情况下,当进水口开口大小总和一样时,通过减小单个进水的高度并且增加进口的个数,可以进一步减小沉淀池内的回流区大小,而且这时平流式沉淀池内进口附近横断面上流速场的分布更均匀。研究结果对平流式沉淀池的优化设计有一定的参考价值。

The effects of different inlet types on the hydraulic characteristics of a horizontal sedimentation tank are simulated by the numerical solution of the gas-liquid two-phase flow model along with the Realizable k-εturbulence model.Free water surface is tracked by using the volume of fluid(VOF)method,and the governing equations are discretized by the finite volume method,and the coupling between velocity and pressure is solved by the pressure implicit operator splitting(PISO)algorithm.The results show that for the design of the inlet of the horizontal sedimentation tank,the arrangement of inlet in the middle of the inlet wall can effectively reduce the size of the backflow area and improve the operation efficiency for the sedimentation tank.When the total height of the inlet is fixed,the number of entrances can be increased by reducing the height of a single inlet,so that the size of the backflow zone in the sedimentation tank can be further reduced,in addition,the velocity fields on the cross-section near the inlet of the horizontal sedimentation tank become more uniform.The results provide a reference for the optimization of design of horizontal sedimentation tanks.