PSD characteristics of gas-liquid two-phase flow in pipeline S-shaped flexible riser

This work presents an experimental investigation on the flow patterns of gas-liquid two-phase flow in pipeline S-shaped flexible riser system. The test loop consists of a horizontal pipeline 114 m in length and 50 mm in i.d., a -2° downward inclined pipe 16 m in length, and an S-shaped riser 15.3 m in vertical height and 24 m in length. Frequency domain analysis on the fluctuation of differential pressure over the riser was carried out and the power spectrum density (PSD) of the corresponding signals was estimated. It's found that as flow pattern transition from typical severe slugging to stable flow occurs, the energy of the fluctuation of differential pressure signal decreases while the dominant frequency of the signal increases. The PSD characteristics of flow patterns are different significantly from each other, indicating that PSD of differential pressure is an effective method for identification of flow patterns in pipeline riser system.