双层桨搅拌槽内气液分散特性的CFD-DPM模拟  

CFD-DPM simulation of gas-liquid dispersion in a dual impeller mixing tank

作　　者：李良超[1] 徐斌[1] 向科峰[1] 

机构地区：[1]西南科技大学制造过程测试技术教育部重点实验室,四川绵阳621010

出　　处：《排灌机械工程学报》2013年第2期151-156,共6页Journal of Drainage and Irrigation Machinery Engineering

基　　金：四川省科技厅应用技术研究与开发项目(2012JY0050);西南科技大学博士研究基金资助项目(11zx7162)

摘　　要：为研究气液搅拌反应器内气体的分散和返混效果对反应器性能的影响,基于计算流体动力学(CFD)软件Fluent 6.2,液相和气相分别采用Euler模型和离散相模型(DPM),对双层六直叶圆盘涡轮桨(6-DT)搅拌槽内气液两相流动进行数值模拟,得到了槽内宏观流动场和气含率分布.通过统计不同时刻逸出液面的示踪气泡数量,对搅拌槽内气体停留时间分布进行了分析.研究结果表明:搅拌槽内液相在每层桨区形成了典型的双循环流型,槽内共有4个循环涡存在,气体易在循环涡涡心处聚集导致局部气含率相对较高,而在槽底区和两桨间区局部气含率相对较低;搅拌槽内气体停留时间分布具有单峰和拖尾现象,并受流型、气泡尺寸和操作条件等影响;提高搅拌转速或减小通气量有利于气体在槽内返混和分散.In order to study the gas dispersion and back-mixing＇s effect on its function in a gas-liquid mixing reactor, on the basis of the computational fluid dynamics （CFD） software package Fluent 6.2, with a Euler model of liquid phase, and a discrete phase mode （I）PM） of gas, discrete gas phase gas- liquid flow in a dual six-blade-disc-turbine （6 - DT） impeller mixing tank was numerically simulated. The macro flow field and gas residence distrihution in the mixing tank was obtained. By counting huh- hies escaped from the vessel at different limes, gas residence time distribution in the tank was ana- lyzed. The simulation resuhs show that typical double circulation pattern is formed for every disc tur- blue and there are four cireulation loops in the mixing tank. Gas easily gathers together at the center of the circulation loops, which leads to high local gas holdup there and relatively low gas holdup in the bottom region and regions between two impellers. The curve of gas residence time distribution displays as a single-peak and a long tail, which is mainly affected by flow patterns, bubble sizes and operating circumstances. To increase impeller speed or decrease gas flow will be helpful for back-mixing and gas dispersion in the mixing tank.

关 键 词：搅拌槽 气液两相流 气含率 离散相模型 数值模拟 停留时间分布 

分 类 号：S277.9[农业科学—农业水土工程] TQ027.2[农业科学—农业工程]