潜水搅拌机三维两相流的数值模拟

A Numerical Simulation of Submersible Mixer in Three-dimensional Flow with Sewage-sludge Two-phase

根据潜水搅拌机实际尺寸,通过PRO/E软件建立三维模型,在Fluent6.3软件平台上,采用滑移网格模型、RNGk-ε湍流模型、混合模型和Simple算法,对搅拌机在清水单相环境下以及污水-污泥两相环境下三维流动进行数值模拟。计算结果表明,搅拌机对水流轴向推动距离大,能满足设定的搅拌池长度要求,形成的搅动半径随水流的推进距离增大而增大。污水-污泥混合液中潜水搅拌机的轴向推流流速与单相流相比有所减小。在搅拌机下游一段距离内,由于搅动半径小,污泥在池底形成沉积。降低潜水搅拌机的安装位置后,搅拌机在搅拌池池底形成的流速变大,污泥沉降变弱。当搅拌机叶轮中心与池底距离减小至0.4m时,搅拌池已无明显污泥沉积现象,污水-污泥混合液的密度分布均匀。

According to the actual size of the mixer ,a 3-D model is established by Pro/E .The sliding mesh technology ,RNG k-εtur-bulence model ,mixture model and Simple algorithm are adopted in the Fluent 6 .3 simulation of single phase flow and sewage-sludge two-phase flow .The results show that the submersible mixer can drive the fluid for a long distance in the axial direction which is able to meet length demand of a mixing tank .The mixing radius becomes larger along the flow direction .The axial velocity established by the submersible mixer in sewage-sludge two-phase flow was smaller than the axial velocity in single phase flow .The small mixing ra-dius leads to sludge deposition in the bottom of the tank within a distance of the mixer downstream .When the installation position of the mixer is reduced ,the velocity on the bottom of the tank becomes bigger ,and sludge settling is weakened .When the distance be-tween the mixer center and the bottom of the tank decrease to 0 .4 m ,there is no obvious sludge sedimentation phenomenon in the tank ,and the velocity and density of sewage-sludge mixture is well-distributed .