Detailed study of single bubble behavior and drag correlations in Newtonian and non-Newtonian liquids for the design of bubble columns
Sprache des Titels:
A study of the effects of fluid type (shear-thinning, Newtonian, and shear-thickening) and periodic shape fluctuations of bubbles on the drag coefficient is presented for three bubble sizes (2 mm, 4 mm and 6 mm), three flow consistency indexes (, , ) and three flow behavior indexes (0.8, 1, 1.2). Computational Fluid Dynamics (CFD) simulations were performed in addition to previous measurements to obtain local data of the flow hydrodynamics. The results were used to evaluate 12 different drag coefficient estimation models, which are essential for the design of bubble columns. The Dijkhuizen et al. and Rodrigue correlations are suitable for the prediction of terminal velocity in both Newtonian and non-Newtonian liquids with high or intermediate viscosity. Finally, a modification of the correlations enables the prediction of small bubble terminal velocity also in low-viscosity liquids.