Dynamic stability of cantilevered piping system conveying slug flow

Abstract

In this paper, the dynamics and stability of a cantilevered piping system conveying slug flow are examined using the stable slug flow model and hysteretic model. The truncation technique of Galerkin and eigenvalue analysis are used to discrete and solve the model equations. The Argand diagrams and stability maps are employed to investigate the effects of superficial gas and liquid velocities and structural damping on the dynamics and stability of the system. The results showed that the increase of superficial gas velocities have a negative influence on the stability under the condition that the dimensionless liquid velocity is caused by the pipe length. In the process of the increase of the superficial gas velocity, the critical flutter velocity reduced and the system underwent several phenomena such as instability-restabilization-instability and mode exchange. However, the superficial liquid velocities have a positive effect on the stability, and the critical flutter velocities increased with it, which resulted in the stability boundary moving upward. It should be pointed out that its increase made the stability of the 4th mode worse and the vibration became more complex. Additionally, the structural damping could improve the stability of the high superficial gas velocity system. This work is helpful to design operating parameters to ensure the safety of the piping system.