Theoretical and experimental study on dynamic characteristics of L-shaped fluid-conveying pipes

Abstract

In this study of fluid-conveying pipe dynamics, it is usually assumed that the shape of the pipe is straight. This paper establishes a flow-induced vibration model of an L-shaped pipe based on the absolute nodal coordinate formulation (ANCF), and mainly studies the effects of fluid velocity, structural parameters, and boundary conditions on the vibration characteristics of the pipe. The results show that the fluid velocity will reduce the natural frequency and affect the modal shapes on the basis of causing static deformation of the pipe. After reaching the critical fluid velocity, the modal combination will occur when the fluid velocity continues to increase. Notably, alterations in pipe length, arc radius, wall thickness, eccentricity and boundary conditions exert diverse effects on the natural frequencies of the pipe. In particular, the arc radius is not involved in the previous study of straight and curved pipe dynamics, so it is analyzed emphatically. Among these variables, the fluid velocity is always a key factor affecting the dynamic characteristics. Finally, experiments and finite element software were used to compare the ANCF method, verifying the effectiveness of the method. Therefore, this paper has developed an effective analytical method to study the flow-induced vibration of complex shaped conveying fluid pipes.