Effect of bubble plume on liquid phase flow structures using PIV

Abstract

In this study, particle image velocimetry (PIV) technique was used for the quantitative visualization and analysis of the liquid phase flow structure driven by a chain of air bubbles in a rectangular bubble column. So, we aimed to provide the recirculation flow pattern and turbulence characteristics in the vicinity of rising bubbles. To this aim, a simple experimental set-up was built, the liquid phase was seeded with 10 µm hallow glass particles. The illumination system consists of a 5 W argon laser source. Images were taken with a high-speed camera (Teledyne Dalsa, Falcon 1.4M100 HG CMOS). The sequence of different bubbles trajectories in water and glycerin solution of high viscosity was studied in order to understand the induced liquid phase flow structure. When the liquid viscosity increases, the instabilities of the liquid velocity field disappears showing the liquid entrainment in the bubbles wake which tends to rise in vertical alignment around the central axis of the column. Furthermore, the viscous force reduces the pseudo-turbulence induced by the rising bubbles, which increases the vertical liquid velocity.