The dynamic behavior of clamped-clamped straight pipes conveying gas-liquid two-phase flow is theoretically investigated, specifically the effect of the flow parameters on the frequency of the system. First, the equation of motion is derived based on the classic Païdoussis formulation. Assuming Euler-Bernoulli beam theory, small-deflection approximation and no-slip homogeneous model, a coupled fluid-structure fourth-order partial differential equation (PDE) is obtained. Then, the equation of motion is rendered dimensionless and discretized through Galerkin’s method. That method transforms the PDE into a set of Ordinary Differential Equations (ODEs). The system frequency is obtained by solving the system of ODEs by allowing the determinant to be equal to zero. System frequencies for different geometries, structural properties and flow conditions have been calculated. The results show t...

The critical flow velocity for a horizontal clamped-clamped pipe conveying two-phase flow is investigated. The system is represented by a coupled fluid-structure fourth-order Partial Differential Equation (PDE). In the case of the multiphase flow, the no-slip homogeneous flow is adopted. The PDE is transformed to a set of first-order ODEs using both Galerkin and state-space methods. The final system of equations represents an eigenvalue problem, where the eigenvalues are the natural frequency of the system. Specialized software has been employed to solve it. Results of critical flow velocity of gas as a function of homogeneous void fraction (fraction of the transversal area occupied by the gas) are presented representing a velocity stability map. The later suggest that the critical flow velocity increases with increasing the homogeneous void fraction. © 2018 Begell House Inc.. All right...