Influence of low-concentration surfactants on characteristics of gas bubbles in a gas-liquid flow in an inclined channel

Experiments were conducted on bubble motion in an inclined tube with a cocurrent liquid flow. The study determined the influence of surfactant concentrations, tube inclination angle and flow velocity on the gas bubble sizes and bubble uprising velocity. It was found that a combination of liquid flow and a surfactant suppresses the bubble coalescence. Under the specific conditions, the drag coefficient for a buoyant bubble in the nearwall flow was calculated. This drag coefficient is proportional to the Weber number both for a bubble in pure water and in water with surfactant.