Experimental Analysis of a Two Phase Air-Water Flow in a Tube of Small Size Diameter Under Various Inlet Conditions

An experimental apparatus is setup to analyze a two phase air-water upward flow in a vertical tube with an inner diameter of 3 mm. Air is axially injected through a microduct of 260 μm inner diameter. Various inlet conditions for air pressure and water flow rate are tested covering a wide range of superficial velocities JL = 0.221 to 0.312 m/s and JG = 0.061 to 0.083 m/s for a given position of air injection (x = 8cm). A fast camera with 250 fps is used to visualize different flow regimes. Experiments showed that the flow type is very sensitive to inlet conditions and several flow regimes were observed namely: the bubbly flow, the slug flow and the annular flow.