Stabilization of a flexible pipe conveying fluid with an active boundary control method

2020 ◽  
Vol 26 (19-20) ◽  
pp. 1824-1834
Author(s):  
Beiming Yu ◽  
Hiroshi Yabuno ◽  
Kiyotaka Yamashita
Keyword(s):  
Flow Velocity ◽  
Control Method ◽  
Bending Moment ◽  
The Self ◽  
Pipe Conveying Fluid ◽  
Stabilization Method ◽  
Critical Flow Velocity ◽  
Complex Eigenvalues ◽  
Excited Oscillation ◽  
Conveying Fluid

A method of stabilizing the self-excited oscillation of a cantilevered pipe conveying fluid because of non–self-adjointness is proposed theoretically and experimentally. Complex eigenvalues denoting the natural frequency and damping of the system vary with an increase in the flow velocity. When the flow velocity exceeds a critical value, the flow-generated damping becomes negative and the pipe is dynamically destabilized. The complex eigenvalues with respect to flow velocity are affected by boundary conditions. We, thus, propose a stabilization control actuating the boundary condition. The stabilization method is carried out by applying a bending moment proportional to the bottom displacement of the pipe. The effect of the proposed control method is shown by investigating the stability for the three lowest modes of the system depending on the feedback gain. It is theoretically clarified that the critical flow velocity is increased by the proposed control method. Furthermore, experiments are performed using a fluid conveying pipe with two piezoactuators at the downstream end. The piezoactuators apply a bending moment at the downstream end of the pipe according to the theoretically proposed method. Experimental results verify that the proposed stabilization method suppresses the self-excited oscillation.

Nonlinear Analysis of L-shaped Pipe Conveying Fluid with the Aid of Absolute Nodal Coordinate Formulation

2021 ◽  
Author(s):  
K. Zhou ◽  
H.R. Yi ◽  
Huliang Dai ◽  
H Yan ◽  
Z.L. Guo ◽  
...  
Keyword(s):  
Theoretical Model ◽  
Flow Velocity ◽  
Absolute Nodal Coordinate Formulation ◽  
Strong Relationship ◽  
Excitation Amplitude ◽  
Pipe Conveying Fluid ◽  
Base Excitation ◽  
Absolute Nodal Coordinate ◽  
Nonlinear Behaviors ◽  
Conveying Fluid

Abstract By adopting the absolute nodal coordinate formulation, a novel and general nonlinear theoretical model, which can be applied to solve the dynamics of combined straight-curved fluid-conveying pipes with arbitrary initially configurations and any boundary conditions, is developed in the current study. Based on this established model, the nonlinear behaviors of the cantilevered L-shaped pipe conveying fluid with and without base excitations are systematically investigated. Before starting the research, the developed theoretical model is verified by performing three validation examples. Then, with the aid of this model, the static deformations, linear stability, and nonlinear self-excited vibrations of the L-shaped pipe without the base excitation are determined. It is found that the cantilevered L-shaped pipe suffers from the static deformations when the flow velocity is subcritical, and will undergo the limit-cycle motions as the flow velocity exceeds the critical value. Subsequently, the nonlinear forced vibrations of the pipe with a base excitation are explored. It is indicated that the period-n, quasi-periodic and chaotic responses can be detected for the L-shaped pipe, which has a strong relationship with the flow velocity, excitation amplitude and frequency.

Parametric Resonances of a Cantilevered Pipe Conveying Fluid: A Nonlinear Analysis

1995 ◽  
Author(s):  
C. Semler ◽  
M. P. Païdoussis
Keyword(s):  
Flow Velocity ◽  
Standard Form ◽  
Harmonic Component ◽  
Harmonic Balance Method ◽  
Pipe Conveying Fluid ◽  
Mean Flow ◽  
Incremental Harmonic Balance Method ◽  
Inertial Terms ◽  
The Stability ◽  
Conveying Fluid

Abstract This paper deals with the nonlinear dynamics and the stability of cantilevered pipes conveying fluid, where the fluid has a harmonic component of flow velocity, assumed to be small, superposed on a constant mean value. The mean flow velocity is near the critical value for which the pipe becomes unstable by flutter through a Hopf bifurcation. The partial differential equation is transformed into a set of ordinary differential equations (ODEs) using the Galerkin method. The equations of motion contain nonlinear inertial terms, and hence cannot be put into standard form for numerical integration. Various approaches are adopted to tackle the problem: (a) a perturbation method via which the nonlinear inertial terms are removed by finding an equivalent term using the linear equation; the system is then put into first-order form and integrated using a Runge-Kutta scheme; (b) a finite difference method based on Houbolt’s scheme, which leads to a set of nonlinear algebraic equations that is solved with a Newton-Raphson approach; (c) the stability boundaries are obtained using an incremental harmonic balance method as proposed by S.L. Lau. Using the three methods, the dynamics of the pipe conveying fluid is investigated in detail. For example, the effects of (i) the forcing frequency, (ii) the perturbation amplitude, and (iii) the flow velocity are considered. Particular attention is paid to the effects of the nonlinear terms. These results are compared with experiments undertaken in our laboratory, utilizing elastomer pipes conveying water. The pulsating component of the flow is generated by a plunger pump, and the motions are monitored by a noncontacting optical follower system. It is shown, both numerically and experimentally, that periodic and quasiperiodic oscillations can exist, depending on the parameters.

210403 Mixed-modal self-excited oscillation of a pipe conveying fluid with an end mass

2011 ◽  
Vol 2011.17 (0) ◽  
pp. 339-340
Author(s):  
Masaaki YAMAMOTO ◽  
Hiroaki FURUYA ◽  
Kiyotaka YAMASHITA ◽  
Hiroshi YABUNO
Keyword(s):  
Pipe Conveying Fluid ◽  
Excited Oscillation ◽  
Conveying Fluid

Control Method for Elimination of Self–Excited Oscillations during Turning

2010 ◽  
Vol 164 ◽  
pp. 171-176 ◽  
Author(s):  
Tomáš Březina ◽  
Jan Vetiška ◽  
Petr Blecha ◽  
Pavel Houška
Keyword(s):  
Tool Wear ◽  
Computer Model ◽  
Pid Controller ◽  
Control Method ◽  
The Self ◽  
Machining Process ◽  
Geometric Accuracy ◽  
Turning Process ◽  
Machined Surface ◽  
Excited Oscillation

The oscillations occurring between the tool and the machined area during the turning process lead to degradation of the machined surface, cause poor geometric accuracy, accelerate tool wear and generate noise. This paper deals with the possibility of elimination of these self-excited oscillations by changing the parameters of the turning process. On the basis of the regenerative principle of self-excited oscillation generation, a computer model of the machining process was developed. Furthermore, a PID controller was proposed to control the compensation of the vibrations and its suitability for elimination of the self-excited oscillations was verified experimentally.

Parametric and Combination Resonances of a Pipe Conveying Pulsating Fluid

1975 ◽  
Vol 42 (4) ◽  
pp. 780-784 ◽  
Author(s):  
M. P. Paidoussis ◽  
C. Sundararajan
Keyword(s):  
Flow Velocity ◽  
Parametric Resonance ◽  
Mean Value ◽  
Pipe Conveying Fluid ◽  
Combination Resonance ◽  
Load Combination ◽  
Parametric Resonances ◽  
The Difference ◽  
Pulsating Fluid ◽  
Conveying Fluid

In this paper we consider the dynamics of a pipe conveying fluid, when the flow velocity is harmonically perturbed about a mean value. Two methods of analysis are presented; Bolotin’s method, which can only give the boundaries of regions of parametric resonance, and a numerical Floquet analysis, which gives also the boundaries of combination resonance. A number of calculations for cantilevered pipes show that, generally, combination resonance is less important than parametric resonance, except for flow velocities near the critical (where the system loses stability in steady flow); parametric resonances are selectively associated with only some of the modes of the system, and combination resonances involve only the difference of the eigenfrequencies. For pipes clamped at both ends the behavior of the system is similar to that of a column subjected to a pulsating load; combination resonances in this case involve the sum of the eigenfrequencies.

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.

Active Feedback Control of Leakage-Flow-Induced Sheet Flutter by Injection and Suction of Fluid at Inlet or Outlet of Passage

2006 ◽  
Author(s):  
Masahiro Watanabe ◽  
Yutaka Koyama
Keyword(s):  
Feedback Control ◽  
Flow Velocity ◽  
The Self ◽  
Control Technique ◽  
Critical Flow ◽  
Leakage Flow ◽  
Critical Flow Velocity ◽  
Active Feedback ◽  
Narrow Passage ◽  
Active Feedback Control

This paper proposes and develops a new non-contact active feedback control of leakage-flow-induced sheet flutter in a narrow passage, by injection and suction of fluid at inlet or outlet of the passage. The strategy of this active control technique is that the active feedback, which is by the activation of the injection/suction of the fluid at the inlet or outlet of the passage, suppresses the original source of the self-exciting fluid force acting on the structure, i.e., cancels the self-excited feedback mechanism. In this paper, the effective suppression of the leakage-flow-induced sheet flutter by the active feedback control technique is demonstrated experimentally. A flexible sheet, as a controlled object, is subjected to fluid flow in a narrow passage. The leakage-flow-induced flutter occurs to the flexible sheet in the translational motion over the critical flow velocity. The leakage-flow-induced sheet flutter is actively controlled and suppressed by the activation of injection/suction of the fluid at the inlet or outlet of the passage. The critical flow velocity under the controlled condition is examined with varying the controller gain and phase-shift between the injection/suction of the fluid and the sensor (vibration displacement) signal of the flexible sheet. As a result, it is indicated experimentally that the active feedback control technique increases the critical flow velocity, and suppress the leakage-flow-induced sheet flutter effectively. Moreover, the control performance is examined experimentally, and stabilization mechanism by the active feedback control is discussed.

Stabilization of Self-Excited Oscillation in a Flexible Fluid-Conveying-Pipe by Position Feedback Control

2012 ◽  
Author(s):  
Hideaki Kosaki ◽  
Hiroshi Yabuno
Keyword(s):  
Control Method ◽  
Unstable Mode ◽  
Adjoint System ◽  
The Self ◽  
Flexible Pipe ◽  
Stabilization Control ◽  
Position Feedback ◽  
Excited Oscillation ◽  
Excitation Mechanisms ◽  
Points Of View

Resonances in flexible fluid-conveying-pipes have been theoretically and experimentally analyzed from the practical and physical points of view. The excitation mechanisms for the resonances have been given considerable attention. In contrast with the analysis of the resonance phenomena, there are few studies on the stabilization control method for the self-excited oscillation of a flexible fluid-conveying-pipe. In this paper, we propose a control method for the self-excited oscillation in a fluid-conveying-pipe theoretically and experimentally. The unstable mode of the fluid-conveying-pipe is not any eigenmodes of the flexible pipe without flow because it is non-self adjoint system. In this paper, by not using the eigenmodes of the flexible pipe without flow deriving the unstable mode shape exactly, we propose a stabilization control method which actuates the unstable mode directly. Therefore, under the proposed control method, the spillover is avoidable and only one sensor is required.

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