| 摘要: |
| 【目的】在同时考虑进水与池内水的污泥质量浓度差异和温度差异的条件下，对平流式二沉池内的异重流现象进行数值模拟，重点研究异重流对池内流场及污泥沉降规律的影响，为优化沉淀池结构设计及提高沉淀池工作效率提供理论支持。【方法】选取Mixture模型和RNG κ-ε 2方程紊流模型，设初始时刻二沉池内水为清水，进水为含一定质量浓度污泥的污水，并通过设置池内水与进水的不同温差模拟夏季与冬季环境，利用模拟数据分析不同时刻各工况下异重流的演变规律。【结果】池内水与进水的单纯污泥质量浓度差异会产生下异重流，小温差低温水与夏季大温差低温水进入均会导致下异重流产生，温差增大，下异重流作用更为明显；高温水进入会同时产生上异重流与下异重流，冬季温差高温水进入时上异重流起主导作用，异重流产生的旋流作用明显，对沉淀池工作效率的影响很大。【结论】温差异重流与污泥质量浓度差异重流本质均为密度差异，低温水进入增强下异重流，高温水进入削弱下异重流，温度影响会消失，污泥质量浓度差异重流作用时间更长。 |
| 关键词: 二沉池 异重流 数值模拟 |
| DOI： |
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| 基金项目:陕西省重点学科建设专项 |
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| Numerical simulation of gravity flow in rectangular sedimentation tanks with the consideration of temperature difference |
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| Abstract: |
| 【Objective】The impact of gravity flow caused by differences of sludge concentrations and temperatures between influent and tank on stream and the sludge concentration distribution was studied.【Method】In the initial time,there was clean water in the tank and the inlet was sewage.The Mixture model and RNG κ-ε two-equation turbulence model were used to simulate different temperature cases in summer and winter.The variation of gravity flow in different times and conditions was studied.【Result】The concentration difference and low-temperature water inflow produced gravity flow in the bottom in summer,while high-temperature water inflow produced the gravity flow both on the top and in the bottom in summer and on the top only in winter.The gyrating current had significant influence on the work efficiency of the tank.【Conclusion】Both concentration and temperature differences were density differences. The low-temperature water inflow strengthened the gravity flow in the bottom while the high-temperature water inflow weakened it.The impact of the temperature would disappear and the impact of concentration differences would exist longer when high-temperature water inflow was used. |
| Key words: rectangular sedimentation tanks gravity flow numerical simulation |
