Film Thickness in Gas-Liquid Two-Phase Flow : 3rd Report, Effects of Obstacle Length and Gap between Obstacle and Tube Surface

抄録

The effects of a flow obstacle set in an air-water two-phase upward flow system are examined on the minimum film thickness occurring upstream and downstream of the obstacle. The obstacles used are several rings different in length and gap between the outer surface of the ring and the inner surface of the tube. Instantaneous flow appearance near the obstacle strongly depends upon the net opening ratio of the obstacle including the gap, which obviously affects the magnitude of minimum film thickness. With the same gap, the reverse flow through gap is pronounced with an increasing length of the obstacle. This leads to an increase of minimum film thickness upstream of the obstacle. The effects of the various parameters of obstacle such as shape, size and gap are summarized using all the experimental results so far obtained.