Dynamics of two-phase flow in vertical pipes

In this study, a novel mathematical model was proposed for the dynamic analysis of two-phase flow in vertical pipes considering different two-phase flow models by including dissipative forces. To model the corresponding two-phase flow, common slip ratio factors were utilized. The Galerkin discretization method and eigenvalue analysis were applied to solve the model equations. A detailed parametric analysis was also performed in order to elucidate the influence of various parameters such as volumetric gas fraction, flow velocity, structural damping and gravity parameter on dynamics of the system, critical flutter velocities and frequencies. The model was validated with experimental data and simulation results reported in the literature It was concluded that the pipes conveying two-phase flow are prone to experience several dynamic phenomena. Stability of the pipe structure was also examined for different two-phase flow models and the results indicated that the instability boundaries are significantly affected by the choice of the model. Furthermore, it was shown that the dynamical response of the pipe is substantially dependent on the volumetric gas fraction. Hence, the gas volume fraction can be introduced as a fundamental parameter for the vibration control of the two-phase flow systems. The results of this study would be beneficial for engineers to optimally design suitable structures for two-phase flow systems. (C) 2019 Elsevier Ltd. All rights reserved.