Experimental and Numerical Investigation of Separator Pressure Fluctuation Effect on Terrain Slugging in a Hilly Terrain Two-Phase Flow Pipeline

Two-phase slug flow in horizontal and near horizontal pipes is a common occurrence in many engineering applications and industrial operations. The objective of this study is to experimentally investigate the effects of separator pressure fluctuations on terrain slugging and slug flow characteristics along and downstream of a hilly terrain pipeline. A further objective is to numerically simulate the flow behavior using a transient multiphase flow simulator to match the simulation predictions with the experimental data. Experimental results revealed that during the separator pressure decline, slug initiation is promoted due to the increase in slip velocity, which enhances the slug initiation mechanisms at the lower elbow. On the other hand, during the separator pressure increase, the analyses show slug suppression. In terms of slug flow characteristics, the mean slug velocity, mean slug length, and maximum slug length increased during the separator pressure decline condition and decreased during the separator pressure increase condition. Furthermore, separator pressure has a significant decreasing effect on slug frequency, maximum slug length, and slug length variance downstream of the hilly terrain section. The statistical analysis shows mixed results of decreasing and increasing trends on mean slug lengths under the fluctuated separator pressure when compared with constant separator pressure conditions. The numerical simulation results showed a close match of liquid holdup downstream of the lower elbow and a fair match at the lower elbow. Furthermore, the model was successful in matching the pressure fluctuation at the lower elbow of the experimental data.