A study of bubble velocity and bubble residence time in a gassed oscillatory baffled column: Effect of oscillation frequency

In this paper, we report an experimental evaluation of velocity and residence time of single bubbles of different sizes in a gassed oscillatory baffled column (OBC) using a high-speed imaging technique. This work is particularly concentrated on the effect of oscillation frequency. The results show that the axial bubble velocities span several orders of magnitude with respect to the mean at an oscillatory frequency greater than 2 Hz. The ratio of the axial to radial bubble velocity components approaches unity at elevated oscillation frequencies. Combining the high-speed imaging with the high-resolution digital particle image velocimetry, we are able to examine the influence of the fluid flow on the bubble motion within the OBC. We also report the direct measurement of residence time of the bubbles within a baffled cell.