Mitigation of pressure fluctuation in two-phase slug flow by rib geometry*

Slug flow has received attention for industrial applications because it is one of the most prevalent and dangerous two-phase flows due to severe pressure fluctuations. The effects of rib elements installed at the inner surfaces of a channel on the flow structure and pressure fluctuations are experimentally investigated with a particular focus on how the rib elements alter slugging phenomena compared to a smooth channel. Pressure fluctuations for the slug in ribbed channels are weakened due to air bubble entrainment. Two distinct mechanisms of air bubble entrainment are suggested to accounts for different levels of mitigation of pressure fluctuation and the increase in flow randomness, which depend on the width-to-height ratio of the rib geometry.