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Bubble formation regimes during gas injection into a liquid cross flow in a conduit
Ist Teil von
Canadian journal of chemical engineering, 2017-02, Vol.95 (2), p.372-385
Ort / Verlag
Hoboken: Wiley Subscription Services, Inc
Erscheinungsjahr
2017
Link zum Volltext
Quelle
Wiley-Blackwell Journals
Beschreibungen/Notizen
A study was performed to characterize the different bubble formation regimes that occur during the process of gas jet injection into a liquid cross flow in a conduit. Air was injected perpendicularly into a turbulent, fully developed water flow circulating through a 12.7 mm square channel. Three different gas injectors, with diameters of 0.27 mm, 0.52 mm, and 1.59 mm were used. The bulk water velocity values ranged between 1.1 and 4.3 m/s. The effects that the gas injection velocity, liquid mean velocity, and injection gas injection diameter have on the process of bubble generation were investigated. A high‐speed visualization technique was used to determine the regimes near the gas inlet region. Four distinct regimes were identified: Single Bubbling (SB), Pulse (P), Elongated Jetting (EJ), and Atomizing Jetting (AJ). It was observed that the shift between regimes occurs gradually, producing the need to identify transitional regions: SBP and PTJ. Sets of independent dimensionless variables were used to categorize the proposed regimes using bubble formation maps. It was determined that the injection diameter plays a primary role in jet formation: as the injection diameter increased, the observable number of regimes decreased, indicating a more stable and continuous process of bubble generation. Empirical correlations that delimit the boundaries between ordered and chaotic bubble generation are presented.