A systematic experimental study and dimensionless analysis of bubble plume oscillations in rectangular bubble columns

Unsteady bubble plume oscillations significantly influence mixing and other transport processes occurring in bubble column reactors. In the present work, oscillations of centrally aerated bubble plumes in rectangular bubble columns were experimentally studied in water and aqueous glycerol solutions. The effects of the superficial gas velocity, aspect ratio, aerated width, needle size and the liquid viscosity on the low-frequency oscillations were investigated. The performance of the dimensionless numbers characterizing the plume oscillation published in the literature was assessed with the present experimental data. Dimensionless analysis was performed and a new empirical correlation was proposed based on the present experiments, and then validated through a large number of available experimental data in the literature. The experimental data and dimensionless analysis presented here can help in understanding the physics of the plume oscillations under various operating conditions. Further, the results can be used for validating corresponding computational models.