Industrial & Engineering Chemistry Research, Vol.57, No.18, 6538-6552, 2018
Vortex Formation and Subsequent Air Entrainment inside a Liquid Pool
The origins of free surface vortex and gas entrainment are investigated within a liquid pool using a rotating cylindrical disc having longitudinal axis normal to the gas-liquid interface with varying submergence from 1.40 to 2.85 times the disc radius (20 mm). A generalized vortex profile is obtained by suitable scaling for a range of rotational Froude numbers (2.38-11.18). The transient evolution rate of the vortex tip followed logarithmic law and is correlated with experimental data of air and glycerin. The axial pull that holds the vortex against gravity is found to be linearly increasing with the rise of disc rotation. Asymmetric vortex profiles with increased extent of asymmetry are obtained upon increase of disc inclination (0-17.45 degrees). Axial and radial circulations are revealed by following the trajectory of a solid particle in the flow field. Entrainment of discrete air volumes is observed from the vortex core at the corresponding Froude number and submergence ratio.