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Continuous formation of microbubbles during partial coalescence of bubbles from a submerged capillary nozzle
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  • Jiguo Tang,
  • Shengzhi Yu,
  • Licheng Sun,
  • Guo Xie,
  • Xiao Li
Jiguo Tang
Sichuan University
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Shengzhi Yu
Wuhan Second Ship Design and Research Institute
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Licheng Sun
Sichuan University
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Guo Xie
Sichuan University
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Xiao Li
Sichuan University
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Abstract

Bubble formation from a downward-pointing capillary nozzle was investigated in this study. The experiments were conducted at gas flow rate of 40-5400 mL/h and inner nozzle radius of 0.030-0.255 mm. Experimental results show that microbubbles were formed continuously at moderate Weber number, which was not reported in pervious investigations with injecting gas through an upward-pointing capillary nozzle. High-speed visualization indicates that the formation of microbubbles arises from the convergence of the capillary waves induced by the partial coalescence of larger bubbles. A bubbling regime map is given to identify the critical conditions for the formation of microbubbles. In the present air-water experiments, the generated microbubbles are 20-170 μm in diameter. From experimental data, a scaling law for microbubble size is proposed as a function of Weber and Bond numbers.

Peer review status:ACCEPTED

22 Jan 2020Submitted to AIChE Journal
24 Jan 2020Submission Checks Completed
24 Jan 2020Assigned to Editor
27 Jan 2020Reviewer(s) Assigned
04 Mar 2020Editorial Decision: Revise Minor
20 Mar 20201st Revision Received
25 Mar 2020Submission Checks Completed
25 Mar 2020Assigned to Editor
26 Mar 2020Reviewer(s) Assigned
27 Mar 2020Editorial Decision: Accept