VOF study of mesoscale bubble flow dynamics in the side-blown gas–liquid two-phase reactor

Abstract

Understanding the flow and mixing characteristics of mesoscale bubbles within side-blown gas–liquid two-phase systems is paramount for the design and optimization of associated industrial processes. This study elucidates the gas–liquid side-blown two-phase reactor, employing the volume of fluid method coupled with the realizable k-ε turbulence model. Following the model validation through experimental measurements, the mesoscale bubble dynamics, flow characteristics, and multiscale coupling mechanisms inherent to side-blown gas–liquid reactor are explored. The key insights can be obtained: (1) the upward trajectory of bubbles originating from side-injection gas can be categorically divided into four phases with different bubble behaviors. (2) A reduction in the ratio of inertial forces to buoyancy forces during bubble ascent induces a decrease in the bubble shape factor. This transition manifests as a shift from vertical to flattened bubble shapes within the transition and plume regions. (3) Bubbles undergo transitions between states characterized by high buoyancy and low surface tension, accompanied by varying levels of viscous forces during their ascent. These dynamic states render bubbles susceptible to breakup. Under conditions of a constant nozzle diameter, the maximum bubble size within the reactor is inherently restricted. (4) Drawing upon the correlation between bubble Weber and Reynolds numbers, a predictive formula for determining the characteristic velocity of bubbles within side-blown reactors is proposed:uc=σ1-0.456(ρlLC)0.456512μl11.36Overall, this work offers meaningful insights into the fundamental mechanisms governing bubble cluster dynamics within side-blown gas–liquid reactors.