Research progress of fluctuating force caused by internal gas-liquid flow

Two-phase flow (Gas-liquid) in pipelines is widely present in many fields, such as nuclear industry, chemical industry, and petroleum transportation. Compared with single-phase flow, the density, pressure, and momentum flux in two-phase flow change greatly in the flow. When flowing through a valve, elbows, tees, and other components, a pulsating force is induced, which is termed as the “flow-induced force.” Flow-induced force causes pipeline vibration. If the vibration frequency is close to the natural frequency of the pipeline, a resonance phenomenon occurs that can further increase the vibration amplitude of the pipeline and consequently cause fatigue damage to the pipeline system. Therefore, research on flow-induced force is of great significance for the safe design and operation of pipelines. In this paper, the research progress on the mechanism, influencing factors, and calculation models of flow-induced force was reviewed. The results show that the change of momentum flux is the dominant factor in causing flow-induced force. The pressure fluctuations, pulsation of the liquid slug, and the volatile liquid wave also contribute to force fluctuation. This study aims to establish a complete theoretical system of flow-induced force mechanism that shows varying wave characteristics with different flow patterns. Most of the current studies focus on single horizontal pipe or riser pipe. With the development of deep-sea oil and gas, demand on gathering and transportation-riser pipeline systems is increased, making it a great engineering significance to study the flow-induced force in a variety of pipeline-riser systems. The empirical and theoretical models are gradually established. The ability of CFD software to simulate flow field and excitation force offers numerous advantages. Therefore, research on the accuracy of CFD software calculation results and the comparison and optimization of effective CFD calculation simulation methods will have important scientific research value for development in the future. This article comprehensively summarized the current research status of gas-liquid two-phase internal flow excitation, which can provide guidance for further related research.