Free vibration and stability analysis of inclined pipes conveying gas-liquid slug flow

In this paper, the free vibration and stability of inclined pipes conveying gas-liquid slug flow are investigated, by considering the intermittency of slug flow and gravity effects of the system. A new lateral motion model has been established based on the stable slug flow dynamics model and the Euler-Bernoulli beam vibration model and is then truncated by the Galerkin approach. The natural frequencies, critical gas velocities, and responses to flow conditions are comprehensively investigated to show the basic dynamic characteristics of inclined pipes. The results show that the gravity effects caused by the inclined angle have a significant effect on the vibration character-istics. The system is less stable with lower critical gas velocity and natural frequency with the increase of inclined angle, due to the gravity-induced compression. For a given inclined angle, the system dynamic responses to superficial gas/liquid velocities are directly related to the mass of liquid per unit length. In addition, the fluctuation of natural frequency caused by the intermit-tency of slug flow decreases with the increase of inclined angle. This study contributes to un-derstanding the complex dynamic behavior of inclined pipes conveying slug flow and promoting pipeline safety.

Automated summary

This paper investigates the free vibration and stability of inclined pipes conveying gas-liquid slug flow, taking into account the intermittency of slug flow and gravity effects. A new lateral motion model is established based on stable slug flow dynamics and Euler-Bernoulli beam vibration models. The study comprehensively explores the natural frequencies, critical gas velocities, and responses to flow conditions, shedding light on the dynamic characteristics of inclined pipes. The results show that the gravity effects caused by the inclined angle significantly influence the vibration characteristics. The study contributes to understanding the complex dynamic behavior of inclined pipes conveying slug flow and promoting pipeline safety.