LINEAR AND NONLINEAR DYNAMICS OF CANTILEVERED CYLINDERS IN AXIAL FLOW. PART 2: THE EQUATIONS OF MOTION

2002 ◽  
Vol 16 (6) ◽  
pp. 715-737 ◽  
Author(s):  
J.-L. LOPES ◽  
M.P. PAÏDOUSSIS ◽  
C. SEMLER
Keyword(s):  
Nonlinear Dynamics ◽  
Equations Of Motion ◽  
Axial Flow ◽  
Flow Part ◽  
Linear And Nonlinear

LINEAR AND NONLINEAR DYNAMICS OF CANTILEVERED CYLINDERS IN AXIAL FLOW. PART 3: NONLINEAR DYNAMICS

2002 ◽  
Vol 16 (6) ◽  
pp. 739-759 ◽  
Author(s):  
C. SEMLER ◽  
J.L. LOPES ◽  
N. AUGU ◽  
M.P. PAÏDOUSSIS
Keyword(s):  
Nonlinear Dynamics ◽  
Axial Flow ◽  
Flow Part ◽  
Linear And Nonlinear

LINEAR AND NONLINEAR DYNAMICS OF CANTILEVERED CYLINDERS IN AXIAL FLOW. PART 1: PHYSICAL DYNAMICS

2002 ◽  
Vol 16 (6) ◽  
pp. 691-713 ◽  
Author(s):  
M.P. PAÏDOUSSIS ◽  
E. GRINEVICH ◽  
D. ADAMOVIC ◽  
C. SEMLER
Keyword(s):  
Nonlinear Dynamics ◽  
Axial Flow ◽  
Flow Part ◽  
Linear And Nonlinear

Linear and Nonlinear Dynamics of Cantilevered Cylinders in Axial Flow

2014 ◽  
Author(s):  
Ahmad Jamal ◽  
Michael P. Païdoussis ◽  
Luc G. Mongeau
Keyword(s):  
Equations Of Motion ◽  
Axial Flow ◽  
Experimental System ◽  
Vital Role ◽  
Viscous Force ◽  
Flexible Cylinder ◽  
Force Coefficients ◽  
Precise Calculation ◽  
Linear And Nonlinear ◽  
Nonlinear Equations Of Motion

Understanding and prediction of the dynamics of slender flexible cylinders in axial flow is of interest for the design and safe operation of heat exchangers and nuclear reactors, specifically that of heat exchanger tubes, nuclear fuel elements, control rods, and monitoring tubes. In such fluid-structure interaction problems, the fluid forces acting on the flexible structure play a vital role in defining its dynamics. Therefore, a precise calculation of the coefficients associated to these forces, such as the longitudinal and normal viscous force coefficients, and base drag coefficient in the equation of motion is imperative. The present work is aimed at (i) calculating these force coefficients for a cantilevered slender flexible cylinder, fitted with an ogival end-piece, in axial flow and (ii) conducting experiments on the same system. In the calculation of these force coefficients, the parameters of the experimental system are used, so that the theoretically predicted dynamics would be representative of the actual physical system. These calculated force coefficients are then incorporated in the linear and nonlinear equations of motion and the predicted dynamics are compared with those of the experiments. The comparison shows good agreement between the theoretical and experimental results.

Dynamics of Slender Tapered Beams With Internal or External Axial Flow—Part 1: Theory

1979 ◽  
Vol 46 (1) ◽  
pp. 45-51 ◽  
Author(s):  
M. J. Hannoyer ◽  
M. P. Paidoussis
Keyword(s):  
Boundary Layer ◽  
Boundary Layer Thickness ◽  
Equations Of Motion ◽  
Axial Flow ◽  
Internal Flow ◽  
External Flow ◽  
High Flow ◽  
Flow Passage ◽  
Flow Part ◽  
Surrounding Fluid

This paper develops a general theory for the dynamics of slender, nonuniform axisymmetric beams subjected to either internal or external flow, or to both simultaneously. The effect of the boundary layer of the external flow is taken into account in the formulation. Typical solutions of the equations of motion are presented for cantilevered conical beams in external flow and for beams with a conical internal flow passage. Such systems lose stability at sufficiently high flow velocity, internal or external, either by flutter or by buckling. The effect of several parameters is investigated. For internal flow, the internal and external shape, whether uniform or conical, and the density of the surrounding fluid have sometimes unexpected effects on stability; e.g., tubular beams lose stability at lower internal flow when immersed in water than when in air. For external flow the effects of conicity, free end shape and boundary-layer thickness are investigated; the latter has a strong stabilizing influence, such that simple theory neglecting this effect results in serious error.

Nonlinear Dynamics of Rotors due to Large Deformations and Shear Effects

2011 ◽  
Vol 110-116 ◽  
pp. 3593-3599
Author(s):  
Muhammad Rizwan Shad ◽  
Guilhem Michon ◽  
Alain Berlioz
Keyword(s):  
Nonlinear Dynamics ◽  
Large Deformations ◽  
Multiple Scales ◽  
Slenderness Ratio ◽  
Nonlinear Differential Equations ◽  
Equations Of Motion ◽  
Circular Cross Section ◽  
Spring Type ◽  
Shear Effects ◽  
Linear And Nonlinear

An analysis of linear and nonlinear dynamics of rotors is presented taking into account the shear effects. The nonlinearity arises due to the consideration of large deformations in bending. The rotor system studied is composed of a rigid disk and a circular shaft. In order to study the combined effect of rotary inertia and shear effects the shaft is modeled as a Timoshenko beam of circular cross section. A mathematical model is developed consisting of 4th order coupled nonlinear differential equations of motion. Method of multiple scales is used to solve these nonlinear equations. Linear and nonlinear dynamic behavior is studied numerically for different values of slenderness ratio r. Resonant curves are plotted for the nonlinear analysis. Due to nonlinearity these curves are of hard spring type. This spring hardening effect is more visible for lower values of r. Also the nonlinear response amplitude is higher when shear deformations are taken into account.

Dynamics of a Supported Cylinder in Axial Flow

2011 ◽  
Vol 99-100 ◽  
pp. 1059-1062
Author(s):  
Ji Duo Jin ◽  
Ning Li ◽  
Zhao Hong Qin
Keyword(s):  
Nonlinear Dynamics ◽  
Numerical Analysis ◽  
Numerical Simulations ◽  
Nonlinear Model ◽  
Dynamical Behavior ◽  
Axial Flow ◽  
Viscous Force ◽  
Friction Drag ◽  
Flutter Instability ◽  
Nonlinear Force

The nonlinear dynamics are studied for a supported cylinder subjected to axial flow. A nonlinear model is presented for dynamics of the cylinder supported at both ends. The nonlinear terms considered here are the quadratic viscous force and the structural nonlinear force induced by the lateral motions of the cylinder. Using two-mode discretized equation, numerical simulations are carried out for the dynamical behavior of the cylinder to explain the flutter instability found in the experiment. The results of numerical analysis show that at certain value of flow velocity the system loses stability by divergence, and the new equilibrium (the buckled configuration) becomes unstable at higher flow leading to post-divergence flutter. The effect of the friction drag coefficients on the behavior of the system is investigated.

Sign in / Sign up

Export Citation Format

Share Document