Extremely large-amplitude oscillation of soft pipes conveying fluid under gravity

  • PDF / 1,178,713 Bytes
  • 20 Pages / 612 x 792 pts (letter) Page_size
  • 62 Downloads / 172 Views

DOWNLOAD

REPORT


Applied Mathematics and Mechanics (English Edition) https://doi.org/10.1007/s10483-020-2646-6

Extremely large-amplitude oscillation of soft pipes conveying fluid under gravity∗ Wei CHEN1,2 , Ziyang HU1,2 ,

Huliang DAI1,2,† ,

Lin WANG1,2,†

1. Department of Mechanics, Huazhong University of Science and Technology, Wuhan 430074, China; 2. Hubei Key Laboratory for Engineering Structural Analysis and Safety Assessment, Wuhan 430074, China (Received Mar. 7, 2020 / Revised May 26, 2020)

Abstract In this work, the nonlinear behaviors of soft cantilevered pipes containing internal fluid flow are studied based on a geometrically exact model, with particular focus on the mechanism of large-amplitude oscillations of the pipe under gravity. Four key parameters, including the flow velocity, the mass ratio, the gravity parameter, and the inclination angle between the pipe length and the gravity direction, are considered to affect the static and dynamic behaviors of the soft pipe. The stability analyses show that, provided that the inclination angle is not equal to π, the soft pipe is stable at a low flow velocity and becomes unstable via flutter once the flow velocity is beyond a critical value. As the inclination angle is equal to π, the pipe experiences, in turn, buckling instability, regaining stability, and flutter instability with the increase in the flow velocity. Interestingly, the stability of the pipe can be either enhanced or weakened by varying the gravity parameter, mainly dependent on the value of the inclination angle. In the nonlinear dynamic analysis, it is demonstrated that the post-flutter amplitude of the soft pipe can be extremely large in the form of limit-cycle oscillations. Besides, the oscillating shapes for various inclination angles are provided to display interesting dynamical behaviors of the inclined soft pipe conveying fluid. Key words

large-amplitude oscillation, soft pipe conveying fluid, gravity effect, flutter

Chinese Library Classification O322, O326 2010 Mathematics Subject Classification 37K45, 37K50

1

Introduction

Fluid-structure interactions (FSIs) and flow-induced vibrations (FIVs) commonly exist in practical engineering and have attracted considerable attention from researchers around the world[1–3] . As one of the typical fluid-structure interaction systems, pipes conveying fluid are likely to experience self-excited oscillations[4] . Besides, this FSI pipe system can be found in ∗ Citation: CHEN, W., HU, Z. Y., DAI, H. L., and WANG, L. Extremely large-amplitude oscillation of soft pipes conveying fluid under gravity. Applied Mathematics and Mechanics (English Edition) (2020) https://doi.org/10.1007/s10483-020-2646-6 † Corresponding authors, E-mail: [email protected], [email protected] Project supported by the National Natural Science Foundation of China (Nos. 11672115, 11622216, and 11972167) ©The Author(s) 2020

2

Wei CHEN, Ziyang HU, Huliang DAI, and Lin WANG

diverse engineering fields, including the heat exchangers of nuclear reactors, chemical processing plan