Velocity Characteristics of Disturbance Wave and Base Film Wave in Gas-Liquid Annular Two-Phase flow in Vertical Capillary Tubes.

We experimentally investigated the velocity characteristics of liquid lumps, such as a liquid slug, a disturbance wave and a base film wave in a vertical capillary tube. The tube diameter ranged from 6.0 mm to 0.5 mm. If the gas flow rate becomes smaller than that in the case of annular flow, the flow patterns of froth and slug flows are observed where the small waves and the large liquid lump such as liquid slug flow together with different velocities. As a definition of the mean velocity of waves or liquid slugs, we proposed a mass-weighted mean velocity which was defined by using the momentum of each wave. Based on the characteristics of velocity of liquid lumps, we proposed a new flow pattern map classifying bubble, slug, froth and annular flows, and we deduced the correlations for the two kinds of wave velocities of annular flow. They agreed well with the experimental results of wave velocity.