旋流沉砂池内高浓度砂石废水的大涡模拟研究,不仅可以揭示旋流沉砂池内复杂流态的瞬时演变,而且能够实现水电工程砂石系统生产废水的达标处理,具有重要的理论与环保意义。该文采用分子动理学方法,从颗粒间相互作用的微观特性角度出发,得到了合理描述高浓度下颗粒间碰撞项的耦合VOF(Volume of Fluid)法的LES-Lagrangian高浓度气.液.固多相流大涡数学模型,亚格子应力采用Smagorinsky亚格子模型封闭,并运用滑移网格技术实现旋流沉砂池内桨叶转动区域的模拟。对西南某水电工程砂石废水处理小试试验的二级旋流沉砂池内湍流场瞬时变化进行了精细模拟;实现了对旋流沉砂池的自由液面以及砂石颗粒运动轨迹的追踪;并讨论了搅拌桨转速对旋流沉砂池内水相、颗粒相的影响,得出旋流沉砂池的最佳桨叶转速为30r/min。同时,将大涡模拟与雷诺时均紊流模型进行了比较,表明大涡模拟可以揭示更为精细的湍流涡结构演变。
The large eddy simulation on high concentration sandstone wastewater in the vortex grit chamber can reveal the transient evolution of a complex flow and is vital to the treatment of wastewater in a hydropower project. An LES-Lagrangian model coupled with VOF method of high concentration sandstone wastewater is established, and the model is gained from the perspective of microscopic interaction between liquid and solid through the molecular kinetic theory. The closure of the subgrid-scale stress model is achieved using the Smagorinsky model and the sliding mesh technique is utilized to achieve the simulation of the cyclone grit tanks blade rotation area. Fine simulation was carried out on the second stage vortex grit chamber for the sandstone wastewater treatment of the pilot test in the southwest. The turbulent flow of liquid and particle were simulated, respectively. Furthermore, Large-eddy simulation and Reynolds turbulence models were compared to show that the large eddy simulation can reveal more sophisticated turbulence phenomenon. Finally the influence of blade rotating speed of the vortex grit chamber was discussed and the optimal rotating speed was 30r/min.