周边进水沉淀池配水槽设计方法的配水均匀性模拟研究

为分析周边进水沉淀池配水槽各种常用设计方法的实际效果,采用计算流体力学(computational fluid dynamics,CFD)方法对直径为20m沉淀池进水槽进行了三维稳态模拟,比较了各种设计方法下配水孔的配水、配泥质量流量的均匀性,模拟以Eulerian-Eulerian multiphase model中的均匀混合连续流体模型(homogeneous model)为框架,包含配水槽中的水、污泥颗粒和水面上部的大气三相,设计方法选择了工程实践中常用的变槽宽定孔径、变槽宽变孔径、定槽宽定孔径和定槽宽变孔径4种配水槽设计方法。模拟结果显示:4种配水槽设计方法中各配水孔质量流量的标准差最小在10%左右,变槽宽的等流速设计整体来说配水、配泥相对均匀,可以考虑优先采用;变孔径设计孔径变化很小,但当采用等槽宽设计时,配水、配泥质量流量的均匀性改善明显。

3D simulation on four design methods of water distribution uniformity for typical peripheral feed sedimentation tank

In order to analyze the uniformity of water distribution for four inflow design methods on peripheral feed sedimentation tank, three-dimensional simulation was carried out by computational fluid dynamics(CFD) technique in a typical sediment tank with diameter 20 m, the uniformities of water and sludge mass flow rates were simulated and compared for four different design methods. The homogeneous sub-model of Eulerian-Eulerian Multiphase Model was adopted in simulation of the tank distribution channel, three phases of water, granular sludge and air(above water) were included, four commonly used design methods in engineering practice-varied-channel-fixed-aperture, varied-channel-varied-aperture, fixed-channel-fixed-aperture and fixed-channel-varied-aperture were selected and simulated. The results showed that none of the four design methods was able to achieve an evenness distribution of water and sludge, which had a minimum 10% of standard deviation of apertures in mass flow rate. The distribution uniformities of water and sludge by varied-channel method were comparatively better and can be employed preferentially. With varied-aperture design method, a very small variation of apertures in diameters was derived, while the distribution evenness of water and sludge were improved obviously with adoption of fixed-channel width method.