Averaged and time-dependent characteristics of the motion of an elongated bubble in a vertical pipe

The motion of elongated (Taylor) bubbles in air-water vertical flow is stud ied by processing consecutive series of digitized video images. The shape o f the elongated bubbles, as well as the velocities of the liquid-gas interf aces, are measured for various flow conditions. The bubble velocity variati on caused by air expansion under the influence of hydrostatic pressure grad ient is measured and compared with model predictions. An oscillatory motion of the bubble bottom is observed. The frequency and the amplitude of these oscillations are studied as a function of bubble length and water flow rat e. This information is essential for accurate modeling of developing gas-li quid slug flow. (C) 1999 Elsevier Science Ltd. All rights reserved.