Quantitative visualization of swirl and cloud bubbles in Taylor–Couette flow

Abstract

We develop a novel method to study the gas phase features in a bubbly Taylor–Couette flow when bubbles are arranged as elevated toroidal strings. The flow is recorded in the front view plane with a highspeed camera for a Reynolds number of 1500 and a global void fraction of 0.14 %. An image processing algorithm is developed to discriminate bubbles accumulated in clouds near the inner cylinder (cloud bubbles) from bubbles trapped in the bulk flow by vortices (swirl bubbles). The analysis of the preferential positions, azimuthal velocities, and equivalent void fraction of clouds and swirl bubbles separately provides a new insight into the dynamics of the bubble’s entrapment.