卡鲁塞尔氧化沟水力学特性的大涡模拟

本文基于大涡模拟中的Smagorinsky-Lilly模型,对Carrousel氧化沟模型进行了水力学特性模拟,并研究了沟内流速和涡量分布规律.速度与压力耦合求解使用了压力隐式算子分裂PISO(Pressure-Implicit with Splitting of Operators)算法,采用VOF(Volume of fluid)方法追踪自由液面.模拟结果表明,回流现象主要出现在上中层混合液中,逆流现象主要出现于上层混合液中;转轮与转刷的推流作用是造成水面变化剧烈的原因;距转轮与转刷较近的区域、转速较快的转轮与转刷区域及直道段转刷下游水面较高一侧中上层区域的涡量较大.根据实验验证,本次模拟结果和实验值吻合度较好,Smagorinsky-Lilly模型可以准确模拟氧化沟水力学特性.

Large eddy simulation of hydraulics characteristic of Carrousel oxidation ditch

The numerical simulation of hydraulics characteristics of a pilot Carrousel oxidation ditch by using a large eddy simulation (LES) with Smagorinsky-Lilly model was conducted to obtain the distribution law of flow velocity and vorticity in oxidation ditches. The coupling velocity and pressure equations were solved with the pressure-implicit method of splitting operators (PISO) algorithm. The VOF (volume of fluid) method was applied to track the free water surface. According to the simulation, the backflow mainly appears in the upper and middle layers, while the countercurrent mainly appears in the upper layer. The plug flow owing to impellers and surface aerators is the reason for the severe change of water surface; and the high vorticity appears in the regions near the impellers and surface aerators with high rotation, and in the middle and upper layers of high water surface side along the downstream of surface aerators. The simulation results are in agreement with the experimental data, which shows that the hydraulic characteristics of oxidation ditch can be accurately simulated by using LES with Smagorinsky-Lilly model.