基于计算流体力学的辐流式二沉池数值模拟

用数值模拟的方法准确描述城市污水处理厂二沉池中的流态及固相分布对保证其稳定运行和出水水质达标至关重要，与其他常用于对二沉池进行数值模拟的经验模型、固体通量模型等相比，计算流体力学（CFD）模型在精度上具有明显优势。以基于计算流体力学的商用软件FLUENT为工具，用欧拉一拉格朗日和欧拉一欧拉方法对辐流式二沉池的流态，尤其是固相行为和分布进行了模拟研究。结果表明，固相颗粒在二沉池中的行为和分布受颗粒的粒径、密度等自身属性以及漩涡等特殊流动现象的影响，呈现出不同于理想沉降理论的轨迹；颗粒粒径及密度越小，颗粒则越易受漩涡等的影响，沉淀池的泥水分离效果也就越差。将模拟结果与实际污水处理厂的数据对比，表明该模拟结果可靠，对工程实际具有一定的指导意义。

Numerical Simulation of Radial Flow Secondary Sedimentation Tank Based on CFD

It is crucial for ensuring stable operation and effluent quality of secondary sedimentation tank in municipal wastewater treatment plants(WWTPs) to numerically simulate the flow profile and its solid distribution accurately.Compared with other commonly used models for numerically simulating secondary sedimentation tank such as empirical models and solid mass flux model,computational fluid dynamics(CFD) model has greater advantages in simulation accuracy.The flow profile,with an emphasis on the solid behavior and distribution in a radial secondary sedimentation tank were simulated by using the commercial CFD software package FLUENT,and the Euler-Lagrange and Euler-Euler methods.The simulation results show that the solid behavior and distribution are influenced by its properties like the diameter and density and by special flow phenomenon like eddy in the tank.Thus the simulated sedimentation trajectory is different from the ideal one.The solid particles become easier to be affected by eddy and the efficiency of solid-liquid separation falls when the diameter and density of sold particles decrease.The comparison between simulation results and real data from WWTP suggests that the simulation is reliable and useful for engineering practice.