辐流式沉淀池温差异重流特性的数值模拟

Numerical simulation of density current caused by temperature on the hydraulic characteristics in the radial flow sedimentation tank

用计算流体力学的方法对某辐流式沉淀池异重流现象进行数值模拟。选用Realizable k-ε湍流模型,设初始时刻沉淀池内充满水,通过设置池内水与进水的不同温度,对沉淀池冬夏季不同时刻各工况下异重流的演变规律进行二维数值模拟。结果表明:夏季产生逆时针的下异重流,低温水自底部向表面蔓延,池内最大流速在沉淀池底部附近;冬季产生顺时针的上异重流,高温水自表面向下部蔓延,池内最大流速在沉淀池表面附近。温差导致的异重流,使沉淀池内产生较大的回流区,影响了沉淀池的流态及污水处理效率。

The paper employed computational fluid dynamics ( CFD) method to simulate the density cur-rent on the hydraulic characteristics in radial flow sedimentation tank .It used Realizable k -εmodel and set up full water in a sedimentation tank at initial time to simulate the property of density current by set -ting the different temperature between inflow water and water in tank in summer and winter .The results show that the density current with counterclockwise vortexes is generated on bottom in summer ,low-tem-perature water flows from bottom to surface ,and the maximum velocity appears near bottom of tank;the density current with clockwise vortexes is generated near top in winter;high-temperature water flows from surface to bottom and the maximum velocity appears near top of the tank .The temperature difference re-sult in density current and produced larger recirculation region in sedimentation tank and affected the wa -ter flow property and the efficiency of wastewater treatment in sedimentation tank .