Bubble formation and swarm dynamics: Effect of increased viscosity

Aiming to make the bridge between the studies of bubble behaviour as single bubble and in bubble columns, the characteristics of bubbles in an aerated column with a low gas content were investigated: bubbles formed at one single 0.5 mm orifice in a partially sparged small lab-scale bubble column were visualized by high -speed camera. The formation process and bubble behaviour at heights of 20 and 40 cm above the orifice were investigated. The bubble size, deformation and velocity were investigated in aqueous glycerol solutions (1 to 10 mPa.s). Average characteristics of the bubbles in swarms were obtained by statistical data processing. It was found that, the bubble formation mechanism governs the size and velocity of bubbles in swarms and that, in the investigated range, viscosity has little effect on the bubble behaviour. Individual bubbles in the swarm differ significantly in their size, shape, and velocity without correlation between these quantities.