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过程工程学报 ›› 2020, Vol. 20 ›› Issue (3): 265-275.DOI: 10.12034/j.issn.1009-606X.219238

• 流动与传递 • 上一篇    下一篇

基于颗粒动力学理论的搅拌器中固液流动的数值模拟

李希铭, 牛胜利*, 曲同鑫, 韩奎华, 路春美, 王永征   

  1. 山东大学能源与动力工程学院,山东 济南 250061
  • 收稿日期:2019-06-21 修回日期:2019-07-09 出版日期:2020-03-22 发布日期:2020-03-20
  • 通讯作者: 牛胜利
  • 基金资助:
    国家自然科学基金;山东省重点研发计划;山东大学青年学者未来计划资助项目

Numerical simulation of solid-liquid flow in stirred tanks based on KTGF model

Ximing LI, Shengli NIU*, Tongxin QU, Kuihua HAN, Chunmei LU, Yongzheng WANG   

  1. School of Energy and Power Engineering, Shandong University, Jinan, Shandong 250061, China
  • Received:2019-06-21 Revised:2019-07-09 Online:2020-03-22 Published:2020-03-20
  • Contact: 胜利 胜牛

摘要: 在欧拉双流体模型基础上引入颗粒动力学理论(KTGF),对带挡板圆盘涡桨式搅拌器内的固液两相流动进行数值模拟。结果表明,搅拌器底部颗粒温度分布与固相浓度分布趋势吻合,转速低于600 r/min时,槽底会形成明显的颗粒沉积,转速从600 r/min增至1500 r/min,堆积区向轴中心收缩,基于颗粒动力学理论可以合理解释挡板及叶轮转速对固相浓度分布的影响。随叶轮转速增大,搅拌器内固液两相湍流运动加剧,颗粒温度、湍动能及轴向速度增加,颗粒分布更均匀,但达到完全悬浮状态后颗粒温度趋于稳定。搅拌器底部和挡板处颗粒堆积导致了局部颗粒浓度增加及颗粒平均自由行程减少,颗粒温度反而降低;同时挡板布置使搅拌器内形成了双循环回路,加强了流体的湍流程度,增强了湍动能,但导致颗粒在挡板处积聚,不利于固相在挡板处均匀分布。

关键词: 搅拌容器, 双流体模型, 两相流, 颗粒动力学理论, 湍流

Abstract: Based on the stirred vessel with baffles and disc turbine paddle, a three dimensional Euler–Euler simulation combined with kinetic theory of granular flow (KTGF) was carried out to explore effects of structure and impeller speed on flow behavior of particles. Furthermore, the simulated solid volume fraction was compared with the experimental solid volume fraction to verify the validity. Contour plots of particle temperature and turbulent kinetic energy on horizontal cross-section were obtained to comprehend the effects of flow patterns and hydrodynamic on solid phase concentration distribution. The results showed that the particle temperature distribution at the bottom of the stirrer vessel was consistent with the solid phase concentration distribution. Based on the kinetic theory of granular flow, the influence of the baffle obstruction and the impeller speed on the solid phase concentration distribution can be reasonably explained. As the impeller speed grew up, the two-phase turbulent motion in the vessel enhanced, the particle temperature, turbulent kinetic energy and axial velocity increased, and the particle distribution became more uniform, but the particle temperature tended to be stable after reaching the complete suspension state. The accumulation of particles at the bottom of the vessel and the baffle led to an increase in local solid volume fraction and a decrease in the average free path of the particles, which in turn reduced the particle temperature. Moreover, the baffles formed a two-loop flow pattern in the vessel, which enhanced the turbulence of the fluid. But it caused accumulation of particles at the baffle, which was not conducive to the uniform distribution of the solid phase at the baffle.

Key words: stirred vessel, two-fluid model, two-phase flow, kinetic theory of granular flow, turbulent flow