Effects of Pressure on Velocity of Liquid Lumps in Horizontal Gas-Liquid Two-Phase Flow

phase flow under a wide range of pressures from near atmospheric pressure to a highly elevated pressure of about 20 MPa. The liquid lumps of interest are liquid slugs, huge waves, disturbance waves and ephemeral large waves. Velocities were determined using time-series signals of cross-sectional mean liquid holdup which were electrically detected at two axially separated locations of the test tube. It is demonstrated how the mean values of liquid lump velocity and its standard deviation depend on the gas and liquid flow rates and pressure. It is obtained that the liquid lump velocity and its standard deviation are obviously affected by the pressure and are related to flow patterns. The comparison of liquid lump velocities between vertical upward flow and horizontal flow is also discussed.