Effect of a small concentration of surfactant on gas bubble sizes for a flow in an inclined channel

The experimental study was performed on the influence of surfactants on the bubble size distribution for a bubbly flow in an inclined tube. Measurements were performed for a round tube with the inner diameter of 32 mm at the gas flow rate 3.3, 5, and 8 ml/min and the tube inclination angles 30–60°. Diameters of gas bubbles and mean diameters were measured from the shadow images of bubbly flow. These parameters were recorded as a function of the tube inclination angle and the distance from gas injection site and the measuring zone. Adding of surfactants reduces the bubble detachment diameter and suppresses bubble coalescence.