Experimental study of the liquid velocity and turbulence in a large-scale air-water counter-current bubble column

Measuring the liquid velocity in large-scale bubble columns with optical methods is complex and usually limited to relatively low volume fractions. In the present study, we complete a database for CFD validation that includes locally resolved information about the bubble size and gas volume fraction with the information about the liquid velocity at different operating conditions. A particle identification and particle-tracking algorithm is developed, which is designed for the problems of particle tracking in bubbly flows. With a background illumination, the volume fraction to which reasonable measurements can be executed is expanded compared to a laser illumination from the side. The time-averaged and transient liquid velocity field is intensively discussed for five superficial gas velocities and four superficial liquid velocities at two measuring heights. A filtering process is proposed with which the results for the turbulent kinetic energy are comparable to previous measurements in tabletop bubble columns. The detailed locally resolved information about the liquid velocity and the previously measured bubble size and gas volume fraction is unique for such a large-scale bubble column. These data might help to validate and improve CFD codes for conditions closer to industrial relevant conditions. Moreover, it can help to improve the understanding of the hydrodynamics in bubble columns in general.