Bubble formation during horizontal gas injection into downward-flowing liquid

The effects of buoyancy on the flow regimes of submerged gas injection were studied in this investigation. A capillary tube submerged in water was used for gas injection in microgravity and terrestrial conditions, and the resulting flow regimes and bubble sizes were documented. The effects of liquid co-flow and reduced surface tension were also analyzed. Under reduced gravity, three flow regimes were observed over the range of conditions tested. At low gas flow rates, the bubbles did not detach from the injector, forming an interconnected bubble cluster that adhered to the injector. Single bubbles started detaching and moving away from the injector when the Weber number reached a value around 3. At gas flow rates corresponding to a Weber number value of 10, the bubble coalescence regime was observed near the injector. It was found that the absence of buoyancy prevented the formation of the jetting regime. For all gas throughputs, the co-flowing liquid aided the detachment of the bubbles, resulting in the generation of more uniform bubbles than in quiescent liquids. The presence of co-flow resulted in a smaller bubble size accompanied by an increased frequency of bubble formation. Reduced surface tension produced a similar effect, resulting in smaller bubbles.

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Experimental Study of Bubble Behaviour in a Flowing Liquid Layer

Volume 3: Student Paper Competition; Thermal-Hydraulics; Verification and Validation ◽

10.1115/icone2020-16397 ◽

2020 ◽

Author(s):

Zhengzheng Zhang ◽

Liangxing Li ◽

Shuanglei Zhang ◽

Afnan Saleem

Keyword(s):

Liquid Layer ◽

Flow Rate ◽

Liquid Flow ◽

Formation Process ◽

Bubble Formation ◽

Water Flow Rate ◽

Nucleation Site ◽

Flowing Liquid ◽

Bubble Detachment ◽

Smooth Channel

Abstract A visualized experimental system is designed and constructed to investigate the bubble dynamic in a flowing liquid layer. Motivated by reducing uncertainties and digging a deep understand on the formation mechanism of boiling bubbles, the bubbles are formed by injecting air through a submerged orifice in our present work, where the influence of thermal physics, nucleation site density and dry spot are stripped. The water flow rate and the air flow rate are in the range of 72–324 ml/min and 0.8–2.0 ml/min, respectively. The bubble formation process in the smooth channel and the rib channel are investigated. The results state that increasing the liquid flow rates lead to the increasing bubble detachment frequency and the decreasing bubble detachment volume. Besides, the larger the liquid flow rate is, the closer the bubble center of mass is to the wall. The rib has a significant influence on the bubble formation process. In the rib channel, it is more difficult for bubbles to detach from the orifice compared that in a smooth channel. Besides, the bubble detachment volume in a rib channel is larger than it in a smooth channel.

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Theoretical Analysis of Bubble Formation in a Co-Flowing Liquid

JOURNAL OF CHEMICAL ENGINEERING OF JAPAN ◽

10.1252/jcej.35.952 ◽

2002 ◽

Vol 35 (10) ◽

pp. 952-962 ◽

Cited By ~ 10

Author(s):

W. B. Chen ◽

Reginald B. H. Tan

Keyword(s):

Theoretical Analysis ◽

Bubble Formation ◽

Flowing Liquid

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Experimental Investigation of Bubble Formation from a Nozzle and an Orifice. 1st report. Frequency of Bubble Formation for Upward Gas Injection.

JAPANESE JOURNAL OF MULTIPHASE FLOW ◽

10.3811/jjmf.11.46 ◽

1997 ◽

Vol 11 (1) ◽

pp. 46-55 ◽

Cited By ~ 6

Author(s):

Manabu IGUCHI ◽

Tomoyuki CHIHARA

Keyword(s):

Experimental Investigation ◽

Bubble Formation ◽

Gas Injection

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Determination of a Bubble Drag Coefficient during the Formation of Single Gas Bubble in Upward Coflowing Liquid

Processes ◽

10.3390/pr8080999 ◽

2020 ◽

Vol 8 (8) ◽

pp. 999

Author(s):

Przemysław Luty ◽

Mateusz Prończuk

Keyword(s):

Drag Coefficient ◽

Chemical Engineering ◽

Liquid Velocity ◽

Bubble Diameter ◽

Bubble Formation ◽

Hydraulic Drag ◽

Gas Bubble ◽

Flowing Liquid ◽

Engineering Research

Bubble flow is present in many processes that are the subject of chemical engineering research. Many correlations for determination of the equivalent bubble diameter can be found in the scientific literature. However, there are only few describing the formation of gas bubbles in flowing liquid. Such a phenomenon occurs for instance in airlift apparatuses. Liquid flowing around the gas bubble creates a hydraulic drag force that leads to reduction of the formed bubble diameter. Usually the value of the hydraulic drag coefficient, cD, for bubble formation in the flowing liquid is assumed to be equal to the drag coefficient for bubbles rising in the stagnant liquid, which is far from the reality. Therefore, in this study, to determine the value of the drag coefficient of bubbles forming in flowing liquid, the diameter of the bubbles formed at different liquid velocity was measured using the shadowgraphy method. Using the balance of forces affecting the bubble formed in the coflowing liquid, the hydraulic drag coefficient was determined. The obtained values of the drag coefficient differed significantly from those calculated using the correlation for gas bubble rising in stagnant liquid. The proposed correlation allowed the determination of the diameter of the gas bubble with satisfactory accuracy.

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