• CN:11-2187/TH
  • ISSN:0577-6686

机械工程学报 ›› 2015, Vol. 51 ›› Issue (16): 185-195.doi: 10.3901/JME.2015.16.185

• 交叉与前沿 • 上一篇    下一篇


梁瑛娜1,2, 高殿荣2, 拜亮2   

  1. 1.燕山大学里仁学院 秦皇岛 066004
    2.燕山大学机械工程学院 秦皇岛 066004;
  • 出版日期:2015-08-20 发布日期:2015-08-20
  • 基金资助:

Numerical Simulation of the Laminar Flow Field and Mixing Time in Stirred Tank with Double Layer Impeller

LIANG Yingna1,2, GAO Dianrong2, BAI Liang2   

  1. 1.Liren College, Yanshan University, Qinhuangdao 066004
    2.College of Mechanical Engineering, Yanshan University, Qinhuangdao 066004
  • Online:2015-08-20 Published:2015-08-20

摘要: 采用Laminar模型、多重参考系法(Multiple reference frame,MRF)和示踪剂浓度法对双层六直叶桨搅拌槽内高黏非牛顿流体层流流场和混合时间进行数值模拟,分析其流动特性、示踪剂扩散过程、示踪剂浓度响应曲线和混合时间;采用示踪粒子法和酸碱指示剂变色法对透明有机玻璃搅拌槽内流动场和混合过程进行试验测定。结果表明,双层桨中间面将示踪剂先控制在加料的半层内随主体介质流动扩散,当浓度差增大后再向另外半层扩散;在搅拌剧烈的桨叶区或在中间面加入示踪剂,可获得更短的混合时间;不同位置混合完成的时间不同,根据搅拌要求合理选择监测点,可避免资源浪费或搅拌不充分;提高搅拌转速,可使搅拌槽内介质混合过程加快,混合时间减小;试验结果验证了数值模拟结果的准确性,为非牛顿流体层流搅拌槽的设计和工程应用提供了理论依据。

关键词: CFD), 层流模型, 混合时间, 计算流体力学(Computational fluid dynamics, 搅拌槽, 示踪剂

Abstract: The laminar model, the multiple reference frame(MRF) and the tracer concentration method are employed to simulate the laminar flow field and the mixing time of highly viscous non-Newtonian fluid in stirred tank with double layer straight impeller. The flow field characteristics, the spreading process of tracer, the responding curves of tracer concentration and the mixing time are analyzed. The tracer particles and the acid-base indicator method are used to measure the flow field and the mixing process in a transparent plexiglass stirred tank in experiment. The results show that the tracer is flowing and diffusing with main medium first in the feeding half of stirred tank because of the intermediate surface between double paddle, then diffusing to the other half when the concentration difference has increased. The shorter mixing time is obtained when feeding tracer at the blade-closed-area which stirred vigorously or at the intermediate surface. Different time are used to complete mixing at different points, so choosing reasonable monitor points with mixing require could avoid resource wasting or insufficient stirring. The mixing process of the medium in stirred tank is faster and the mixing time is shorter when increasing stirring speed. The accuracy of the numerical simulation results is verified by the experimental results. The research provides the theory basis for the design and engineering application of the laminar flow stirred tank with non-Newtonian fluid.

Key words: computational fluid dynamics(CFD), laminar model, mixing time, stirred tank, tracer