SCI和EI收录∣中国化工学会会刊

Chinese Journal of Chemical Engineering ›› 2019, Vol. 27 ›› Issue (10): 2325-2336.DOI: 10.1016/j.cjche.2019.01.031

• Fluid Dynamics and Transport Phenomena • Previous Articles     Next Articles

Numerical study on solid suspension characteristics of a coaxial mixer in viscous systems

Baoqing Liu, Zilong Xu, Qing Xiao, Bolin Huang   

  1. College of Energy Engineering, Zhejiang University, Hangzhou 310027, China
  • Received:2018-09-27 Revised:2018-12-14 Online:2020-01-17 Published:2019-10-28
  • Contact: Baoqing Liu
  • Supported by:
    Supported by the Natural Science Foundation of China, Zhejiang Province (LY16B060003) and the National Natural Science Foundation of China (21776246).

Numerical study on solid suspension characteristics of a coaxial mixer in viscous systems

Baoqing Liu, Zilong Xu, Qing Xiao, Bolin Huang   

  1. College of Energy Engineering, Zhejiang University, Hangzhou 310027, China
  • 通讯作者: Baoqing Liu
  • 基金资助:
    Supported by the Natural Science Foundation of China, Zhejiang Province (LY16B060003) and the National Natural Science Foundation of China (21776246).

Abstract: A coaxial mixer consisting of an anchor and a Rushton turbine was selected as the research object, whose solid suspension characteristics were studied with the help of Computational Fluid Dynamics (CFD) method. Based on the Eulerian-Eulerian method and modified Brucato drag model, the just-suspension speed of impeller was predicted, and the simulation results were in good agreement with the experimental data. The quality of solid suspension under different rotation modes was also compared, and the results showed the coaxial mixer operating under co-rotation mode could get the best performance, and a larger anchor speed was beneficial to solid suspension by enhancing the turbulent intensity at the bottom. Compared with the anchor, the inner Rushton turbine played a dominant role in solid suspension due to its high rotational speed, whereas an extremely high inner impeller speed would make the uniformity of solid distributions become worse. Additionally, the effects of solid phase properties were also investigated, the results revealed that the higher the overall solid volume fraction and the smaller the Shields number, the worse the performance of solid suspension, meanwhile the solid suspension was more susceptible to solid density compared with particle diameter within the same Shields number gradient.

Key words: Coaxial mixer, Mixing, Two-phase flow, CFD

摘要: A coaxial mixer consisting of an anchor and a Rushton turbine was selected as the research object, whose solid suspension characteristics were studied with the help of Computational Fluid Dynamics (CFD) method. Based on the Eulerian-Eulerian method and modified Brucato drag model, the just-suspension speed of impeller was predicted, and the simulation results were in good agreement with the experimental data. The quality of solid suspension under different rotation modes was also compared, and the results showed the coaxial mixer operating under co-rotation mode could get the best performance, and a larger anchor speed was beneficial to solid suspension by enhancing the turbulent intensity at the bottom. Compared with the anchor, the inner Rushton turbine played a dominant role in solid suspension due to its high rotational speed, whereas an extremely high inner impeller speed would make the uniformity of solid distributions become worse. Additionally, the effects of solid phase properties were also investigated, the results revealed that the higher the overall solid volume fraction and the smaller the Shields number, the worse the performance of solid suspension, meanwhile the solid suspension was more susceptible to solid density compared with particle diameter within the same Shields number gradient.

关键词: Coaxial mixer, Mixing, Two-phase flow, CFD