Numerical study of transient flow characteristics of gas-liquid two-phase flow in inclined upward tube under periodic vibration

The transient flow characteristics of gas-liquid two-phase flow in inclined upward tubes exhibit a high degree of complexity. The tube vibration caused by multiple uncertain factors, such as seawater impacts or subsea earthquakes, poses more significant challenges for flow safety assurance. Thus, it becomes increasingly crucial to explore the transient flow characteristics of gas-liquid two-phase flow in inclined upward tubes under various vibration conditions. In this paper, the transient flow characteristics of gas-liquid two-phase flow in an inclined upward tube under different vibration conditions are numerically studied based on CFD dynamic mesh technique. In the current study, the studied parameters include vibration direction (heaving, transverse and coupling), vibration amplitudes (0.5D, 1.0D and 1.5D), and inlet velocity (jsg=0.5∼1.0m/s; jsl=0.1∼1.0m/s). The transient flow structure, cross-sectional void fraction and pressure drop are analyzed. The findings indicate that the transient flow structure of the slug flow demonstrates periodic variation characteristics under transverse and coupling vibrations, and the cross-sectional void fraction increase. For transition flow, the cross-sectional void fraction increases under transverse and coupling vibrations, while displays an increase initially and subsequently a decrease significant with an increase in the heaving vibration amplitude. Additionally, all considered vibration conditions intensify the pressure drop of the transition flow and decrease the cross-sectional void fraction of the turbulent flow.