Film Thickness in Gas-Liquid Two Phase Flow : 2nd Report, Effect of four-rectangular-obstacle inserted into tube

Abstract

An additional experiment was made of the effects of flow obstacle on minimum film thickness in gas-liquid two-phase upward flow. The obstacle used in this experiment consists of four rectangular shaped pieces jutting from the inner surface of the tube. The results suggest that the present type of obstacle also has strong effects on the film thinning process upstream of the obstacle, which are similar to those of the circular ring used as the obstacle in the 1st report. However, because the liquid film can flow between the pieces, a reverse flow across the obstacle is easy to occur during the drainage period existing at low air velocities, and the amount of liquid accumulated below the obstacle at relatively high air velocities is reduced. On account of these effects, the minimum film thickness upstream of the obstacle increases at low air velocities and decreases at high air velocities. On the other hand, the minimum film thickness in the downstream region is almost the same as that without obstacle.