On the Hydrodynamics of Bubble Columns: Comparison of Experimental Measurements with Computational Fluid Dynamics Calculations


On the Hydrodynamics of Bubble Columns: Comparison of Experimental Measurements with Computational Fluid Dynamics Calculations

Vanga, B. N. R.; Krepper, E.; Zaruba, A.; Prasser, H.-M.; de Bertodano, L.

The hydrodynamics of a rectangular bubble column operating in the dispersed bubbly regime has been experimentally and numerically investigated. The bubble column was locally aerated using a sparger located in the center of the bottom plate. The experimental studies involve wire-mesh tomography measurements for void fraction and bubble size distributions and digital image rocessing of high speed camera images for estimation of bubble velocities, size distributions and flow patterns. Experiments were performed for various aspect ratios (height of water column to width ratio) and superficial gas velocities. Computational fluid dynamic calculations of transient flow for the above bubble column were performed using an Eulerian-Eulerian two fluid model. Turbulence in the liquid phase was accounted for, using the k-epsilon turbulence model. The effect of the gas phase on turbulence in the continuous phase was modeled using Sato’s eddy viscosity model for bubble-induced turbulence. A systematic analysis of the interfacial momentum transfer terms has been conducted. It was found that the non-drag bubble forces play a very prominent role in the predicting the correct flow pattern and void fraction distributions. In the calculations, the lift force and the wall force were considered. A ‘wall peak’ in the time averaged void fraction distribution has been experimentally observed and this cannot be predicted without including these non-drag forces in the numerical calculations. In this paper, experimental data are compared with the results of the numerical simulations.

Keywords: bubble columns; two-phase flow; modelling; turbulence; interfacial momentum transfer

  • Lecture (Conference)
    5th International Conference on Multiphase Flow, ICMF 04, 30.05.-04.06.2004, Yokohama, Japan
  • Contribution to proceedings
    5th International Conference on Multiphase Flow, ICMF 04, 30.05.-04.06.2004, Yokohama, Japan, paper 264

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Publ.-Id: 6413