Studies of vertical annular gas-liquid flows

Three types of vertical flowing films were studied. These are the free falling film, the falling film in the presence of countercurrent gas flow and the upward moving film due to concurrent flow of gas. An experimental program was performed based on a new electrochemical method for the dynamic measurement of the magnitude and the direction of the wall shear stress, and on a conductance wire probe for the simultaneous measurement of the film thickness. The data obtained for the free falling film reveal a strong length effect on the wavy film structure. Analysis of the data taken with countercurrent flow of gas shows that even at the flooding condition, the film flow is controlled by downward wave motion. Analyses of upward film flow data in a variety of ways suggest that at low gas rates the motion of the interface is controlled by a process of switching between steady states of the system.