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过程工程学报 ›› 2022, Vol. 22 ›› Issue (12): 1643-1651.DOI: 10.12034/j.issn.1009-606X.221386CSTR: 32067.14.jproeng.221386

• 研究论文 • 上一篇    下一篇

柱状颗粒沉降过程的CFD-DEM联合仿真和实验研究

刘佳君1， 刘雪东1,2*， 吕圣男1， 高华鑫1， 邵佳伟1， 张红红1   

  1. 1. 常州大学机械与轨道交通学院，江苏 常州 213164 2. 江苏省绿色过程装备重点实验室，江苏 常州 213164
  • 收稿日期:2021-11-23 修回日期:2022-02-21 出版日期:2022-12-28 发布日期:2022-12-30
  • 通讯作者: 刘雪东 lxd99@126.com
  • 基金资助:
    中国石化股份有限公司重点研发计划项目

CFD-DEM and experimental research on sedimentation process of columnar particles

Jiajun LIU1,  Xuedong LIU1,2*,  Shengnan LÜ1,  Huaxin GAO1,  Jiawei SHAO1,  Honghong ZHANG1   

  1. 1. School of Mechanical Engineering and Rail Transit, Changzhou University, Changzhou, Jiangsu 213164, China 2. Jiangsu Key Laboratory of Green Process Equipment, Changzhou, Jiangsu 213164, China
  • Received:2021-11-23 Revised:2022-02-21 Online:2022-12-28 Published:2022-12-30
  • Contact: Xuedong LIU lxd99@126.com

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摘要： 针对柱状催化剂颗粒相对于球形颗粒的不同运动特性，选择不同长度直径为2 mm的5种柱状颗粒，采用CFD-DEM数值模拟仿真，研究柱状颗粒在管状容器中沉降的运动行为，并建立柱状颗粒沉降试验台，采用高速摄像拍摄的方法进行实验研究。结果表明，在不同位置释放相同直径和长度的柱状颗粒时，靠近壁面释放的颗粒会在沉降过程中向中心漂移，且比中心释放的颗粒沉降更慢，时间更长；改变柱状颗粒与水平面的夹角，在圆管中心释放颗粒，最终颗粒都会旋转至水平状态，与水平面夹角越大，底部所受阻力越大，转动持续时间随之增加；推导柱状颗粒沉降斯托克斯方程，并通过实验数据对方程中的阻力系数进行修正，将修正后的阻力系数导入用户自定义函数(UDF)计算颗粒沉降末速度，相对误差从原来使用球形颗粒阻力系数的50%下降到17%以内，模拟较为可靠。

关键词: 柱状颗粒, 沉降, 计算流体力学, CFD-DEM联合仿真, 高速摄像

Abstract: Solid-liquid two-phase flow widely existed in daily life. It was widely used in petrochemical, medical, environmental protection and other fields. The common particles in solid-liquid two-phase flow were spherical, cylindrical and rectangular. According to the elongated shape characteristics and particle orientation of cylindrical catalyst particles relative to spherical particles, five cylindrical particles with diameters of 2 mm and different lengths were selected to study. The computational fluid dynamics coupled discrete element method (CFD-DEM) was used to simulate the motion behavior of cylindrical particles during the settlement of tubular containers. Cylindrical particles were constructed by the combination of spherical element method and multi sphere method. A cylindrical particle sedimentation test-bed was established, and the sedimentation process of cylindrical particles in tubular container was verified by high-speed camera. The results showed that the particles near the wall were affected by the wall effect. When cylindrical particles with the same diameter and length were released at different positions, the particles drifted to the center in the process of sedimentation. The settling velocity of particles near the wall was slower and the settling time was longer. When releasing the columnar particles at the same position of the circular tube by only changing the angle between the cylindrical particle's principal axis and the horizontal plane, the particles would eventually rotate to a state where the principal axis was parallel to the horizontal plane. In the process of sedimentation, the greater the angle between the particle principal axis and the horizontal plane, the greater the resistance on the windward surface of the particle, and the particle rotation time would also increase. The Stokes equation for the settlement of cylindrical particles was derived, and the resistance coefficient in the Stokes equation was modified through the experimental data. The resistance coefficient corrected by the experiment was introduced into user defined function (UDF), and the end velocity of particle settlement was simulated and calculated. When using the resistance coefficient of spherical particles, the error was 40.6%. After correction, the relative error was reduced from 50% to less than 17%.

Key words: columnar particles, sedimentation, computational fluid dynamics,CFD, CFD-DEM, high-speed camera