Abstract
Liquid phase hydrodynamics in an aerated tank (ID = 0.19 m) stirred by a half elliptical blade disk turbine (HEDT) have been investigated using particle image velocimetry (PIV) under both aerated and unaerated conditions. The effect of the gas flow rate on the aerated mean velocity of the liquid phase, turbulent kinetic energy and turbulent kinetic energy dissipation are discussed, and their comparisons with those under unaerated conditions are also carried out. Under aerated conditions, the presence of gas does not remarkably change the velocity pattern of the liquid phase. When the direction of the liquid flow is the same as the buoyancy, the liquid is accelerated up to 10.4% by bubbles at position of z/T=0.8 and r/T=0.45; while the liquid flow reversely, the liquid is decelerated about 37.5% under the gas flow rate of 0.2 vvm at the position of z/T=0.25 and r/T=0.45. The turbulent kinetic energy in the bulk flow increases after introducing gas phase, and the average turbulent kinetic energy of the upper, middle and lower regions at 0.2 vvm are increased by 37.3%, 37.8% and 142.7%, respectively. Large-eddy PIV approach is carried out to estimate the distribution of the turbulence kinetic energy dissipation. The result shows that the distribution of the turbulent kinetic energy dissipation is similar as those of turbulent kinetic energy.
Published Version
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