Liquid Film Characteristics of Vertical Upward Annular Flow under Low Surface Tension

The liquid film characteristics of the upward gas-liquid annular flow with low surface tension are investigated experimentally by Planar Laser-induced Fluorescence (PLIF) technology. The aqueous solution of polyoxyethylene-lauryl-ether was used as the low surface tension liquid phase in the experiment. The digital image processing technology was employed to obtain the liquid film information. The velocity of disturbance wave was calculated based on gray-scale cross-correlation algorithm. Experimental results show that there is a significant influence of low surface tension on the upward annular flow liquid film characteristics. Under a low surface tension, the gas-liquid interface disturbance is intensified with a reduced disturbance amplitude, and the average thickness of annular liquid film is reduced. The flow characteristics of liquid film are further studied through the disturbance wave velocity, and the flow characteristic in time and frequency domains.