Numerical study of bubble coalescence and breakup characteristics under high shear force
It is of great significance to understand the coalescence and breakup mechanism of bubbles as well as their growth and motion characteristics in the shear field for the optimal design of blades in a gas-liquid stirred tank.Under different shear forces,gas-liquid bi-phase flow field was obtained by coupling Eulerian-Eulerian model with population balance model(PBM).Influence of shear force,intake gas velocity under high shear force and bubble tower height on the coalescence and breakup of bubbles was studied.Combining with bubble coalescence and breakup model,the coalescence and break mechanism of bubbles under high shear force was revealed.Results show that the shear force dominated the breakup of bubbles.Small shear force had little effect on the breakup of bubbles.The increase of shear force enhanced the breakup of bubbles with the significant increase of small bubbles fraction.Effect of intake gas velocity and tower height on the coalescence and breakup of bubbles was not obvious under high shear force.
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