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.

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.

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.

Analysis of coupled-mode flutter of pipes conveying fluid on the elastic foundation

2000 ◽  
Vol 21 (10) ◽  
pp. 1177-1186 ◽  
Author(s):  
Wang Zhong-min ◽  
Feng Zhen-yu ◽  
Zhao Feng-qun ◽  
Liu Hong-zhao
Keyword(s):  
Elastic Foundation ◽  
Coupled Mode ◽  
Pipes Conveying Fluid ◽  
Conveying Fluid

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.

Modal Analysis of Multi-Span Pipes Conveying Fluid Based on Three Different FSI Methods

2012 ◽  
Vol 594-597 ◽  
pp. 2525-2528
Author(s):  
Ting Zhang ◽  
Huan Huan Ding ◽  
Yan Su ◽  
Hong Chen
Keyword(s):  
Modal Analysis ◽  
Solid Mechanics ◽  
Small Range ◽  
Reasonable Result ◽  
Nature Frequency ◽  
Pipes Conveying Fluid ◽  
Velocity Changes ◽  
The One ◽  
Conveying Fluid ◽  
Good Agreement

The modal analysis of pipes conveying fluid considering the influence of Fluid-Structure Interaction (FSI) is always a topic in flow and solid mechanics fields worth study. Three methods of coupling, the direct FSI method, the one-way FSI method and the bidirectional FSI method, with the velocity’s influence on pipe system’s natural frequency were considered in this study. The results of pipe’s dynamic behavior indicate that the two-way FSI method can get a more reasonable result. Furthermore, when velocity changes in a small range far from critical velocity, velocity makes very little influence on system’s nature frequency. The result was compared with conclusion in the literature and very good agreement was found.

Dynamics of Timoshenko Beams Conveying Fluid

1976 ◽  
Vol 18 (4) ◽  
pp. 210-220 ◽  
Author(s):  
M. P. Paidoussis ◽  
B. E. Laithier
Keyword(s):  
Equations Of Motion ◽  
Beam Theory ◽  
Present Theory ◽  
Timoshenko Beams ◽  
Bernoulli Beam ◽  
Finite Difference Technique ◽  
Observed Behaviour ◽  
Pipes Conveying Fluid ◽  
Euler Bernoulli Beam ◽  
Conveying Fluid

The dynamics of pipes conveying fluid is described by means of the Timoshenko beam theory. The equations of motion are derived and solved ( a) by a finite-difference technique, and ( b) by a variational method. It is shown that the latter is the more efficient method. The eigenfrequencies of the system and its stability characteristics are compared with results obtained previously using the Euler-Bernoulli beam theory, and it is shown that in certain cases (e.g. short pipes) the two sets of results diverge. Experiments indicate that the present theory is more successful in predicting the observed behaviour. Furthermore, the present theory shows that, in some cases, cantilevered pipes may lose stability by buckling, whereas previous theories indicate that the system always loses stability by flutter.

Vibration Characteristics of Hollow Symmetrical Blades Based on Thin Shell Theory

1978 ◽  
Vol 100 (1) ◽  
pp. 183-187 ◽  
Author(s):  
A. M. Al Jumaily ◽  
L. L. Faulkner
Keyword(s):  
Thin Shell ◽  
Shell Theory ◽  
Beam Theory ◽  
Continuous System ◽  
Functional Representation ◽  
Hollow Blade ◽  
Vibrational Characteristics ◽  
Continuous Boundary ◽  
Laboratory Models ◽  
Thin Shell Theory

This paper presents the results of investigating the vibrational characteristics of a hollow symmetrical blade based on thin shell theory which allows closed function representation of vibrational characteristics which are inaccessible using beam theory. A modified shell theory is presented and used for the analysis. The hollow blade is considered as a continuous system constructed from two cantilever circular cylindrical shells by matching the continuous boundary conditions. This technique is used to express the results in a continuous function analytical formation. The method presented is clearly for long hollow blades and does not require the computer storage of numerical methods. Comparison is made between the present technique, the beam theory, and experimental data for two laboratory models. The formulation can be extended to most types of blades and still retain the functional representation. This type of analysis may be quite useful when utilized judiciously with other methods such as finite elements.

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