Experimental study of liquid velocity profiles in large-scale bubble columns with particle tracking velocimetry

A complete knowledge of bubble column fluid dynamics relies on understanding both the “global-scale” and the “local-scale” phenomena and coupling between the phases. Unfortunately, most of the previous literature focused on the “global-scale” fluid dynamics, whereas a limited attention was devoted to the “local-scale” fluid dynamics. In this study, we contribute to the present-day discussion through an experimental study concerning the local liquid velocity field in the pseudo-homogeneous flow regime. The experimental study, based on a particle-identification and particle-tracking algorithm, was conducted in a large-diameter and large-scale air-water bubble column (with a height of 5.3 m and inner diameter of 0.24 m) operated in the counter-current mode. We considered gas superficial velocities in the range of 0.37–1.88 cm/s and liquid superficial velocities up to −9 cm/s. The time-averaged and the transient liquid velocity field were obtained and critically discussed for five superficial gas velocities and four superficial liquid velocities at two measuring heights. Subsequently, the local locally resolved information concerning the liquid velocity were coupled with the previously measured bubble size distributions and local void fractions, to provide a complete description of the “local-scale” fluid dynamics. In addition, these data would help in the validation of numerical codes to predict industrial-scale relevant conditions.