Numerical investigation of bubble dynamics and multi-scale flow characteristics in the bottom-blown gas–liquid reactor

Comprehending the multi-scale characteristics of gas–liquid two-phase systems is of utmost importance in augmenting reaction rates and enhancing the efficiency of resource and energy utilization in industrial processes. In this study, the experimentally verified large eddy simulation coupled with volume of fluid model is employed to investigate the dynamics of bubble swarms and the macroscope flow characteristics in gas–liquid two-phase systems. The results indicate that: (1) in the bubble rising process, momentum region, transfer region, plume region, and liquid surface region with different bubble features can be identified. The bubble swarms display various behaviors such as breakup and merging, path instability, and vortex shedding throughout their ascent. The existence of a high-speed region in the hydrodynamically stable quasi-elliptical wake region expedites the trailing bubble. Furthermore, the amalgamation of vortex shedding and shape alteration influences the stability of the bubble rising path. (2) An increase in the number of orifices results in a more uniform distribution of bubbles and a bubble plume flow skewed more towards the central region, attributable to the Bernoulli effect. Nonetheless, the overall gas holdup of the system decreases with an increasing number of orifices. (3) The number of large vortex structures and the gas–liquid contact area expand with an increasing number of orifices. This study provides valuable insights into the dynamics and mechanisms of bubble swarms, which are of great significance for the design, operation, and optimization of gas–liquid two-phase systems in various industrial applications.