Nonconservative pipes conveying fluid: evolution of mode shapes with increasing flow velocity

2014 ◽  
Vol 21 (16) ◽  
pp. 3359-3367 ◽  
Author(s):  
L Wang ◽  
HL Dai ◽  
Q Ni
Keyword(s):  
Flow Velocity ◽  
Mode Shapes ◽  
Fluid Evolution ◽  
Pipes Conveying Fluid ◽  
Conveying Fluid

scholarly journals Influence of Dry Friction on the Dynamics of Cantilevered Pipes Conveying Fluid

2022 ◽  
Vol 12 (2) ◽  
pp. 724
Author(s):  
Zilong Guo ◽  
Qiao Ni ◽  
Lin Wang ◽  
Kun Zhou ◽  
Xiangkai Meng
Keyword(s):  
Flow Velocity ◽  
Friction Force ◽  
Dry Friction ◽  
Critical Flow Velocity ◽  
Pipe System ◽  
Pipes Conveying Fluid ◽  
Cantilevered Pipe ◽  
The Stability ◽  
Friction Parameters ◽  
Conveying Fluid

A cantilevered pipe conveying fluid can lose stability via flutter when the flow velocity becomes sufficiently high. In this paper, a dry friction restraint is introduced for the first time, to evaluate the possibility of improving the stability of cantilevered pipes conveying fluid. First, a dynamical model of the cantilevered pipe system with dry friction is established based on the generalized Hamilton’s principle. Then the Galerkin method is utilized to discretize the model of the pipe and to obtain the nonlinear dynamic responses of the pipe. Finally, by changing the values of the friction force and the installation position of the dry friction restraint, the effect of dry friction parameters on the flutter instability of the pipe is evaluated. The results show that the critical flow velocity of the pipe increases with the increment of the friction force. Installing a dry friction restraint near the middle of the pipe can significantly improve the stability of the pipe system. The vibration of the pipe can also be suppressed to some extent by setting reasonable dry friction parameters.

Nonlinear Free Vibration of Spinning Viscoelastic Pipes Conveying Fluid

2018 ◽  
Vol 10 (07) ◽  
pp. 1850076 ◽  
Author(s):  
Feng Liang ◽  
Xiao-Dong Yang ◽  
Wei Zhang ◽  
Ying-Jing Qian
Keyword(s):  
Oil And Gas ◽  
Multiple Scales ◽  
Equations Of Motion ◽  
Drill String ◽  
Mode Shapes ◽  
Flowing Fluid ◽  
Nonlinear Dynamical ◽  
Pipes Conveying Fluid ◽  
Spinning Speed ◽  
Conveying Fluid

Drill strings are one of the most significant rotor components employed in oil and gas exploitation. In this paper, an improved dynamical model of drill-string-like pipes conveying fluid is developed by taking into account the axial spin, fluid–structure interaction (FSI), damping as well as curvature and inertia nonlinearities. The partial differential equations of motion are derived by two sequential Euler angles and the Hamilton principle and then directly handled by the multiple scales method. The nonlinear amplitudes, frequencies and whirling mode shapes are all investigated towards various system parameters to display the nonlinear dynamical characteristics of such a special rotor system coupled with FSI. It is revealed that the nonlinear amplitudes and frequencies are explicitly dependent on the spinning speed, while the flowing fluid mainly contributes to the linear frequencies, and consequently influences the nonlinear amplitudes and frequencies. The FSI effect and axial spin can both improve the forward procession mode and suppress the backward one, while both procession modes will be suppressed by the viscoelastic damping. The pipe will ultimately present a forward as well as decayed whirling motion for the fundamental mode.

Dynamic Behavior of Continuous Cantilevered Pipes Conveying Fluid Near Critical Velocities

1981 ◽  
Vol 48 (4) ◽  
pp. 943-947 ◽  
Author(s):  
J. Rousselet ◽  
G. Herrmann
Keyword(s):  
Partial Differential Equations ◽  
Differential Equations ◽  
Flow Velocity ◽  
Averaging Method ◽  
Nonlinear Partial Differential Equations ◽  
Plane Motion ◽  
Pipe Conveying Fluid ◽  
Pipes Conveying Fluid ◽  
Critical Velocities ◽  
Conveying Fluid

The plane motion of a cantilevered pipe conveying fluid is examined when the flow velocity is in the neighborhood of that generating flutter. In contrast to previous studies, the flow velocity is not prescribed as a constant, but is determined from the laws of motion. We are thus led to a system of two nonlinear partial differential equations which are coupled through the nonlinear terms. The solution is found by the use of the Krylov-Bogoliubov averaging method and the results are discussed indicating the effect of nonlinearities.

scholarly journals Investigation of approximate mode shape and transition velocity of pipe conveying fluid in failure analysis

2022 ◽  
Vol 14 (1) ◽  
pp. 168781402110724
Author(s):  
Wasiu Adeyemi Oke ◽  
Oluseyi Afolabi Adeyemi ◽  
Ayodeji Olalekan Salau
Keyword(s):  
Failure Analysis ◽  
Mode Shape ◽  
Dynamic Responses ◽  
Mode Shapes ◽  
Pipe Conveying Fluid ◽  
Transition Velocity ◽  
Modal Characteristics ◽  
Pipes Conveying Fluid ◽  
Composite Pipes ◽  
Conveying Fluid

Structures dynamic characteristics and their responses can change due to variations in system parameters. With modal characteristics of the structures, their dynamic responses can be identified. Mode shape remains vital in dynamic analysis of the structures. It can be utilized in failure analysis, and the dynamic interaction between structures and their supports to circumvent abrupt failure. Conversely, unlike empty pipes, the mode shapes for pipes conveying fluid are tough to obtain due to the intricacy of the eigenvectors. Unfortunately, fluid pipes can be found in practice in various engineering applications. Thus, due to their global functions, their dynamic and failure analyses are necessary for monitoring their reliability to avert catastrophic failures. In this work, three techniques for obtaining approximate mode shapes (AMSs) of composite pipes conveying fluid, their transition velocity and relevance in failure analysis were investigated. Hamilton’s principle was employed to model the pipe and discretized using the wavelet-based finite element method. The complex modal characteristics of the composite pipe conveying fluid were obtained by solving the generalized eigenvalue problem and the mode shapes needed for failure analysis were computed. The proposed methods were validated, applied to failure analysis, and some vital results were presented to highlight their effectiveness.

Study on the Influence of Gravity Factor on Parametric Resonance of Pipe Conveying Fluid

2013 ◽  
Vol 300-301 ◽  
pp. 1235-1238
Author(s):  
Bing Chen ◽  
Ming Le Deng ◽  
Zhong Jun Yin
Keyword(s):  
Flow Velocity ◽  
Parametric Resonance ◽  
Resonance Region ◽  
Critical Conditions ◽  
Pipe Conveying Fluid ◽  
First Order ◽  
Comparison Results ◽  
Pipes Conveying Fluid ◽  
The One ◽  
Conveying Fluid

The averaging method has been applied to calculate the critical conditions of parametric resonance instability of the first order mode shape of clamped-clamped and pinned-pinned pipes conveying fluid. The influence of gravity factor on parametric resonance of pipe conveying fluid, with different supporting forms and different flow velocity, has been studied based on the comparison results of gravity factor being considered and neglected. It is concluded that gravity factor has a greater influence on parametric resonance region of pinned-pinned pipe than the one of clamped-clamped pipe, and, at a higher flow velocity, gravity factor is more influential to both pinned-pinned pipe and clamped- clamped one.

Flutter of Conservative Systems of Pipes Conveying Incompressible Fluid

1975 ◽  
Vol 17 (1) ◽  
pp. 19-25 ◽  
Author(s):  
M. P. Paidoussis
Keyword(s):  
Flow Velocity ◽  
Shell Theory ◽  
Beam Theory ◽  
High Flow ◽  
Coupled Mode ◽  
Conservative Systems ◽  
Pipes Conveying Fluid ◽  
The One ◽  
Thin Shell Theory ◽  
Conveying Fluid

An examination of the dynamics of beam-like motions of pipes conveying fluid, with both ends clamped, is presented by means of beam theory and, in the case of thin-walled pipes, by thin-shell theory. Both theories predict that the system loses stability by divergence at sufficiently high flow velocity, and that at higher flow velocity the system is subject to coupled-mode flutter; between the two instabilities there is sometimes a region where the system is completely stable. The critical flow velocities obtained by beam theory and by shell theory are compared, and it is shown that the former coverage towards the latter as the length of the pipe increases. Finally, the existence of coupled-mode flutter in gyroscopic conservative systems, such as the one investigated here, is briefly discussed.

Vibration and Stability of Helical Pipes Conveying Fluid

1987 ◽  
Vol 109 (4) ◽  
pp. 402-410 ◽  
Author(s):  
C.-N. Fan ◽  
W.-H. Chen
Keyword(s):  
Natural Frequencies ◽  
Equations Of Motion ◽  
Mode Shapes ◽  
Critical Flow ◽  
Helical Pipe ◽  
End Conditions ◽  
Finite Element Procedure ◽  
Pipes Conveying Fluid ◽  
Conveying Fluid ◽  
Flow Velocities

This paper presents an accurate finite element procedure for the vibration and stability analysis of helical pipe conveying fluid. The kinematics of the helical pipe are derived including the effects of arbitrary curvatures and torsions in a nonorthogonal helical coordinate system. The equations of motion are derived from the Hamilton’s principle for mass transport system and the shear deformation and rotary inertia are also considered. The 3-node space-curved isoparametric element is used. The natural frequencies, mode shapes and critical flow velocities of buckling are studied for different end conditions. The significant influence of torsion effects on the calculation of natural frequencies and critical flow velocities is found. To demonstrate the validity and accuracy of the techniques developed, several numerical examples are illustrated.

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