Behaviour of a Gas Bubble in a Liquid Flow with a Linear Velocity Profile

Abstract

Lift force acting on an air bubble, a liquid droplet or a solid spherical particle in a uniform shear flow was investigated both experimentally and theoretically to obtain fundamental knowledges of a lateral void distribution in a gas-liquid two-phase bubbly flow. Two side walls of a vertical test channel were constructed by driven belts running counterwise for each other. In this way a flow field with a linear velocity profile was produced in a measuring section in the central part of the channel. From the time trace of a bubble, a droplet or a solid sphere introduced in this flow field, the lift force was obtained experimentally. It was found that the direction of the lift force acting on a deformable particle such as a bubble and a liquid droplet is opposite to that on a solid sphere. Based on a theoretical consideration a correlation was proposed to estimate the lift force acting on a bubble or a droplet.