温度异重流对竖流式二沉池影响的三维数值模拟

Three-Dimensional Numerical Simulation of the Influence of Temperature Density Flow on Vertical Secondary Sedimentation Tank

为了探究温度异重流对竖流式二沉池的流场影响,使用RNG k-epsilon湍流模型和mixture模型,对其进行三维瞬态数值模拟从而探究不同进水温度和不同回流比对二沉池流场的影响。结果表明:高温水入流会产生上异重流,其特征是混合液沿中心管上翻至出水槽而导致出水带泥;而低温水入流会产生下异重流,其特征是沿沉淀池池壁会由产生翻泥现象而影响固液分离效率。增大二沉池污泥回流可适当减缓高温入流产生的上异重流对二沉池的工作效率影响,在相同温差下,回流比越大,上异重流的影响越小。

In order to explore the flow field of vertical secondary sedimentation tank which the temperature density flow affects, the three-dimensional transient numerical simulation is carried out by RNG k-epsilon turbulence model and mixture model to explore the impact of different inlet water tem-perature and reflux ratio on the flow field of secondary sedimentation tank. The results show that: the high-temperature water inflow will produce the up density flow, which is characterized by the mixed liquid turning up along the central pipe to the outlet tank, leading to discharge of mud. However, the low-temperature water inflow will produce the down density flow, which is charac-terized by the mud turning phenomenon along the wall of the sedimentation tank, which will affect the solid-liquid separation efficiency. Increasing the sludge backflow of secondary sedimentation tank can reduce the influence of up density flow on the working efficiency of secondary sedimenta-tion tank. Under the same temperature difference, the greater the reflux ratio, the smaller the in-fluence of the overweighted flow.