Two-phase computational fluid dynamics assessment of bubble plume in air-diffuser destratification

Abstract

Hydrodynamic flow patterns and behavior induced by bubble plumes in a linearly stratified fluid are studied. To optimize an air-diffuser destratification system, we used computational fluid dynamics software to develop a two-phase (air-water) destratification model. The model enables us to simulate complicated stratification conditions with different densities and source strengths. We conducted laboratory experiments to verify the model in thermally stratified fresh water. The computational fluid dynamics model performs well when the plume number ranges from 30 to 600. We successfully explain various phenomena, including the hydrodynamic behavior of bubble plumes and turbulent three dimension flow patterns. Our approach provides a level of detail not possible with other one-dimensional plume models. Contrary to the findings of other researchers, our experiments and computational fluid dynamics simulation indicate that the energy conversion efficiency increases as plume number increases; moreover, the three flow types do not occur in the same plume number regimes defined in other research. The difference is apparently due to the effect of the bubble size.