Research on the Gas-Liquid Two-Phase Distribution Behavior and Influencing Factors of Swirling Flow in Horizontal Pipe

Gas-liquid two-phase swirling flow is widely used for gas-liquid separation in the power, chemical, petroleum, and nuclear industries. However, the majority of current research on swirling flow focuses on identifying flow patterns and does not pay more attention to topics such as the boundary where swirling flow forms. The length and diameter of the central gas core are the main focus of the current studies as well as the distribution patterns of gas-liquid two-phase. Comparative studies on the gas-liquid distribution morphology, such as whether the gas phase is separated and the separation mode, are lacking. In this paper, a combination of visual experimental observations and numerical simulations of Computational Fluid Dynamics (CFD) is used to investigate the formation conditions of gas-liquid two-phase swirling flow in three types of cyclonic components. The results show that the minimum superficial liquid velocity for the formation of swirling flow in the horizontal tube is about 0.375 similar to 0.82 m/s when the superficial gas velocity is less than 10 m/s. The formation of swirling flow is almost independent of the geometric swirl number and superficial liquid velocity when the superficial gas velocity is greater than 10 m/s. At low inlet superficial velocities, the tangential velocity determines the transition from swirling flow to stratified flow. However, at higher inlet superficial velocities, the decay of the cyclonic field is mainly affected by the wave amplitude of the gas-liquid interface. In both co-current and counter-current horizontal inline gas-liquid cyclone separators, the flow split is related to the vortex core breakdown of the central gas core. In addition, the numerical simulation results show that the breakdown of the vortex core is related to the pressure distribution inside the separator. This work enriches the study of swirling flow and provides a basis for the performance improvement of inline gas-liquid cyclone separators.