挡板长度对辐流式沉淀池流场与污泥浓度场影响的数值模拟  

Influence of baffle length on flow and sludge concentration fields in a radial sedimentation tank

作　　者：魏文礼[1] 李盼盼[1] 洪云飞[1] 刘玉玲[1] 

机构地区：[1]西安理工大学陕西省西北旱区生态水利工程重点实验室,陕西西安710048

出　　处：《西北农林科技大学学报（自然科学版）》2016年第7期228-234,共7页Journal of Northwest A&F University(Natural Science Edition)

基　　金：国家自然科学基金项目(51578452);陕西省工业科技攻关项目(2016GY-180);陕西省科学研究计划项目(2014K15-03-05)

摘　　要：【目的】研究进水口处垂直挡板长度对沉淀池内速度场和污泥质量浓度场分布的影响,为实际工程中沉淀池的优化设计提供参考。【方法】采用简化的多相流混合(Mixture)模型,对辐流式沉淀池内液固两相流水力特性进行二维数值模拟,选取RNGk-ε紊流模型封闭时均流方程,采用有限体积法对微分方程进行离散,使用压力隐式算子分裂PISO(Pressure-Implicit with Splitting of Operators)算法进行速度与压力耦合求解。然后设初始时刻沉淀池内为清水,进水为含一定质量浓度污泥的污水,在此条件下模拟并分析不同挡板长度时2个模型沉淀池内速度场和污泥质量浓度场的变化规律。【结果】沉淀池内有1个大回流区和2个小回流区,长挡板模型的回流区比短档板模型小;沉淀池内污泥分布呈现分层现象,且长挡板模型内污泥到达出口的时间比短档板模型长;长挡板模型的小流速区域比短档板模型大,更有利于污泥的沉降。【结论】辐流式沉淀池进口处设置长挡板有利于提高沉淀池的运行效率。[Objective] The influence of inlet vertical baffle on distribution of flow field and sludge mass concentration field was studied in a sedimentation tank to provide reference for optimization design of actual sedimentation tanks. [Method] The simplified Mixture multiphase model was used to study the hydraulic characteristics of solid-liquid two-phase flow in a radial sedimentation tank by 2D numerical simulation. The RNG k-ε turbulent model was used to close the time-averaged flow equations. The finite volume method was used to discretize the differential equations,and the coupling velocity and pressure equations were solved with the pressure-implicit method of splitting operators （PISO） algorithm. At the initial time, the sedimentation tank was filled with stationary clear water and sewage ran through inlet. The variation of flow field and sludge mass concentration field in different times was then studied. [Result] There were three recirculation zones in the sedimentation tank,a big one and two small ones. The model with a longer feed flow baffle caused a smaller recirculation zone. The distribution of sludge showed stratified phenomenon in the sedimentation tank. Sludge took a longer time to arrive at export in the model with a longer feed flow baffle. The region of fluid particles with a smaller velocity was bigger in the model with a longer feed flow baffle,which was beneficial to sludge sedimentation. [Conclusion] The sedimentation tank with a longer feed flow baffle can produce better running efficiency.

关 键 词：沉淀池 挡板长度 数值模拟 速度场 污泥质量浓度场 

分 类 号：X703[环境科学与工程—环境工程]