Numerical study of vortex–bubble interaction mechanism in bubble breaker using the volume of fluid and large eddy simulation method

Effectively removing or reducing the number of bubbles doped in a material is of great significance to stabilize product characteristics and improve production safety. In this paper, the volume of fluid method and large eddy simulation method are used to numerically simulate the bubble dynamics in unsteady turbulence near a four-blade propeller in a bubble breaker at different speeds. The results show that the final rupture position of the bubble occurs in the main vortex region. The interaction mechanism between the vortex and the bubble involves not only the impact of the small vortex on the bubble but also the influence of the tail vortex pair, which exerts two strong torsional stresses in opposing directions. This interaction ultimately results in the breakup of the bubble. In addition, three different fracture modes were observed: Ring Broken Mode (RBM), Dented pull out Broken Mode (DBM), and Tear Broken Mode (TBM). The bubble breaking process is quantitatively described in terms of vorticity change rate and critical Weber number (We). It is found that DBM does not occur at high rotational speed, and TBM occurs faster and more violently with increase in vorticity change rate. After multiple cycles, the vorticity change in RBM is similar to that at medium speed, and when the change rate reaches its maximum, the size of the fragmentation bubble becomes smaller.