Experimental and numerical studies of the hydrodynamics in a bubble column

The hydrodynamics in a bubble column of 140 mm diameter and a height of 650 mm was analysed using a phase-Doppler anemometer (PDA). In order to allow the application of PDA, the bubble column was aerated with relatively fine bubbles with a size spectrum between about 0.3 and 1.5 mm. The gas hold-up was varied in the range between 0.5 and 3%. The measurement of the liquid v elocities in the bubble swarm was done by adding fluorescing seed particles . Moreover, the Euler/Lagrange approach was extended to allow time-dependen t calculations of the flow evolving in a bubble column based on the Reynold s-averaged Navier-Stokes equations together with the k-epsilon turbulence m odel which was extended to account for turbulence modification by the bubbl es. The coupling between the phases was considered through momentum source terms and source terms in the k- and epsilon-equation which also include th e effect of wake-generated turbulence. The bubble motion was calculated by solving an equation of motion taking into account drag force, added mass, b uoyancy and gravity, and the transverse lift force. In order to identify th e relative importance of the different physical phenomena involved in the m odel, a detailed parametric study was performed and the numerical results w ere compared with the measurements for validation. (C) 1999 Elsevier Scienc e Ltd. All rights reserved.