<p>Discrete bubbles can be effectively cracked and dispersed in a Venturi channel with its unique structural characteristics, and the general Venturi channel has been widely used in the practical engineering. However, the popularization and amplification design of Venturi channel were hindered by the ambiguity of the mechanism of bubble breakup. In this paper, visual experiment indicated that the bubble breakup characteristics was related to the recirculation flow of the diverging section. Image post-processing was carried out with Image J software to quantitatively characterize the flow field characteristics of recirculation flow. The recirculation flow magnitude and the amount of recirculation flows on the boundary wall area of the diverging section were then investigated. The experiment results indicated that the bubbles experienced serious deceleration process in the diverging section. And the bubble transportation heading to the sidewall region was induced by the recirculation vortexes. Various characteristics of bubble breakup were shown under different vortex magnitude. In the case of large vortex, the bubble is mainly broken into two daughter bubbles. While in the case of small vortex, the bubble is broken by multiple daughter bubbles. The bubble breakup ratio was defined as the ratio between the initial bubble particle size and the daughter bubble size. The functional relationship among the bubble breakup ratio, Reynolds number, gas-water ratio, vortex magnitude and vortex account was also obtained. Trying to increase the account of small vortexes in the diverging section can significantly improve the ability of bubble breakup.</p>

An Investigation on the Bubble Breakup Characteristics by Recirculation Flow in a Venturi Channel

Paper Proceedings: https://asmedigitalcollection.asme.org/FEDSM/FEDSM2021/volume/85284

ASME 2021 Fluids Engineering Division Summer Meeting (FEDSM2021)

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