Abstract
Fine bubbles have been widely applied in many fields such as industry, medical engineering and agricultures. Therefore, many attentions have been paid to the study of fine bubble generations in order to increase the yield while decrease the cost. However, the generation process of fine bubbles is a quite complicated process in which multiple hydrodynamic forces are interacted in the gas-liquid two-phase flow. Many studies focus on the techniques of the converging-diverging nozzle (venturi tube) generator, which is famous for its simple and cheap features, and generates fine bubbles by using the miniaturization phenomenon of bubbles occurring in the venturi tube. However, the impact conditions on the amount and size of bubbles such as nozzle geometry and bleed air haven’t been investigated clearly. In this work, we implement many experiments on the venturi tube fine bubble generators with different geometries and generating conditions, and evaluate different factors impacting the production components such as the volume and the bubble size. The experimental results show that the supersonic flow filed in the venturi tube promotes the miniaturization of the bubbles, and the convergent angle of the nozzle and air bleed have a great impact on the size and volume of bubbles.
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Abbreviations
- A* :
-
area ratio of the bubble in the aquarium
- D a :
-
minimum diameter of the bubble/µm
- p in :
-
inlet supply pressure of water to the nozzle/kPa
- Δp :
-
pressure difference of minimum wall pressure and atmospheric pressure/kPa
- Q w :
-
flow rate of water in the nozzle/L·min−1
- Q i :
-
flow rate of bleed air/mL·min−1
- θ :
-
diverging angle of the nozzle/degree
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Acknowledgement
The experiments of bubble particle size measurement are supported by the Mishima Laboratory in Fukuoka University.
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Jiang, X., Yasunobu, T., Nakamura, A. et al. Miniaturization of Bubbles by Shock Waves in Gas-Liquid Two-phase Flow in the Venturi Tube. J. Therm. Sci. 30, 1068–1076 (2021). https://doi.org/10.1007/s11630-021-1432-5
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DOI: https://doi.org/10.1007/s11630-021-1432-5