SCI和EI收录∣中国化工学会会刊

›› 2016, Vol. 24 ›› Issue (10): 1325-1334.DOI: 10.1016/j.cjche.2016.05.027

• Fluid Dynamics and Transport Phenomena • 上一篇    下一篇

Interactions between two in-line drops rising in pure glycerin

Li Rao, Zhengming Gao, Ziqi Cai, Yuyun Bao   

  1. State Key Laboratory of Chemical Resource Engineering, School of Chemical Engineering, Beijing University of Chemical Technology, Beijing 100029, China
  • 收稿日期:2015-12-18 修回日期:2016-04-29 出版日期:2016-10-28 发布日期:2016-11-19
  • 通讯作者: Ziqi Cai,E-mail address:caiziqi@mail.buct.edu.cn;Yuyun Bao,E-mail address:baoyy@mail.buct.edu.cn.
  • 基金资助:
    Supported by the National Natural Science Foundation of China (21376016, 21506005).

Interactions between two in-line drops rising in pure glycerin

Li Rao, Zhengming Gao, Ziqi Cai, Yuyun Bao   

  1. State Key Laboratory of Chemical Resource Engineering, School of Chemical Engineering, Beijing University of Chemical Technology, Beijing 100029, China
  • Received:2015-12-18 Revised:2016-04-29 Online:2016-10-28 Published:2016-11-19
  • Supported by:
    Supported by the National Natural Science Foundation of China (21376016, 21506005).

摘要: The behaviors of time-dependent interaction between two buoyancy-driven in-line deformable drops rising in pure glycerin at Re<1 were studied, where the diameter for the leading drops ranged from 9.51 mm to 12.6 mm and for trailing drops from 12.7 mm to 15.8 mm. The situation while a larger drop chasing a smaller onewas specifically consideredwhich typically led to the smaller drop "coating" the larger one. Two approaches, the geometric feature approach and the energy change one, were used to judge the starting and ending times of the interaction between twodrops. Based on a conicalwakemodel, the drag coefficient of twoapproaching drops was calculated. Due to the approaching effect of the trailing drop, the leading drop was accelerated and the average drag coefficientwas smaller than that for a free rising single drop. The frequency spectrums of the lateral oscillation of two drops during the interaction were obtained by using Fourier analysis. The oscillation frequency of the interactional drops was also different from that for a free rising single drop because of the wake effect produced by the leading drop. Due to a superposition of the drop shape oscillation and the drop internal circulation, the transverse oscillation frequencies of two drops have the same trend during the approaching process.

关键词: Two in-line drops, Oscillation, Fourier analysis, Energy analysis

Abstract: The behaviors of time-dependent interaction between two buoyancy-driven in-line deformable drops rising in pure glycerin at Re<1 were studied, where the diameter for the leading drops ranged from 9.51 mm to 12.6 mm and for trailing drops from 12.7 mm to 15.8 mm. The situation while a larger drop chasing a smaller onewas specifically consideredwhich typically led to the smaller drop "coating" the larger one. Two approaches, the geometric feature approach and the energy change one, were used to judge the starting and ending times of the interaction between twodrops. Based on a conicalwakemodel, the drag coefficient of twoapproaching drops was calculated. Due to the approaching effect of the trailing drop, the leading drop was accelerated and the average drag coefficientwas smaller than that for a free rising single drop. The frequency spectrums of the lateral oscillation of two drops during the interaction were obtained by using Fourier analysis. The oscillation frequency of the interactional drops was also different from that for a free rising single drop because of the wake effect produced by the leading drop. Due to a superposition of the drop shape oscillation and the drop internal circulation, the transverse oscillation frequencies of two drops have the same trend during the approaching process.

Key words: Two in-line drops, Oscillation, Fourier analysis, Energy analysis