Experiment And Numerical Simulation On Transition Of Cryogenic Gas-Liquid Flow Bubbly Flow To Slug Slow In Vertical And Inclined Pipes

Inevitable heat leak of pipelines and storage tanks will lead to in-ternal gasification of cryogenic liquid. As a result, small bubbles occur and finally coalesce into slug bubbles. Slug bubbles squeeze cryogenic liquid out of pipeline, causing liquid eruptions, this phenomenon is gey-sering. So the phenomenon of geyser is based on the slug bubble for-mation. Geyser will cause pressure fluctuations, which is similar with water hammer phenomenon,and may lead to the damage of transmission lines, catheters and stent valve. Similar accidents are common in the aerospace and petrochemical industry process. With the continuous de-velopment of the study on these areas, the security and stability of transporting and storage of cryogenic liquid have become increasingly crucial. Therefore, it is significant to study on the mechanism of slug bubble formation and the flow characteristics of slug flow for control-ling the occurrence of geysering.Visualization research of nitrogen slug flow was performed to study the influences of tube diameter and inclination angle on the basic law of cryogenic gas-liquid bubbly-slug transition flow by using statistical methods. Distribution of initial position and velocity of slug bubbles were analyzed. Theoretical analysis on the growth and movement of small diffusing bubbles were carried out. The cryogenic gas-liquid flow was numerical simulated by commercial CFD software Fluent. Flow field velocity around the initial Taylor bubbles which was in good agreement with experiment results.The results show that the average transition position of cryogenic bubbly-slug flow increases with the pipe diameter. And as the inclina-tion angle of the pipe increases, the average initial position increases first and then decreases. Dispersion of initial position of Taylor bubbles becomes larger with inclination angle of the pipe increases. The maxi-mum occurs as the inclination angle range from 20°to 45°, then get cen-tralized. It gets smaller with the diameter increases in vertical pipes. The average velocity of initial Taylor bubbles increases as the diameter in-creases. As the inclination angle increases, It increases first and then de-creases, with the Maximum velocity atθ=30°.