The post-hopf-bifurcation response of a loosely supported cylinder in an array subjected to cross-flow. Part I: Experimental results
TL;DR: In this article, the dynamic response of a loosely supported cylinder, unstable in its first TSP-inactive mode (i.e., when no support is provided by the Tube Support Plate), is investigated experimentally.
About: This article is published in Journal of Fluids and Structures.The article was published on 1994-01-01. It has received 17 citations till now. The article focuses on the topics: Intermittency & Hopf bifurcation.
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TL;DR: In this article, the stability behavior of a rotated triangular array is investigated in detail, with a fully flexible array, a single flexible tube, and a finite number of flexible tubes at several locations within the otherwise rigid array.
39 citations
TL;DR: In this article, the effects of support clearance and flow orientation for various support geometries and lattice-bar support offset are investigated for a loosely supported heat exchanger tube excited by turbulence.
35 citations
TL;DR: In this paper, a robust feedback controller is proposed to suppress flutter-type chaotic vibrations in baffled heat exchanger tubes, which are caused by the fluid dynamic forces on the tube which behave as a negative damping element.
28 citations
TL;DR: In this paper, a nonlinear quasi-steady model for the analysis of the dynamics of a loosely supported cylinder, which takes into account position-dependent nonlinear fluid forces as well as nonuniform flow, is formulated.
24 citations
TL;DR: In this paper, the authors investigated the mechanisms leading to chaos for a cylinder within a loose circular support and found that at higher flow velocities, a subcritical bifurcation of a period-1 orbit leads to type I intermittency.
Abstract: Cylinder arrays in heat exchangers exhibit complex dynamical behaviour when fluid excitation results in impacting with loose supports. In this paper, the mechanisms leading to chaos for a cylinder within a loose circular support are investigated. Of particular interest is the intermittency transition to chaos that has been found to arise. For a 2 degree-of-freedom (d.o.f.) system, it is found that type III intermittency results from destabilization of a simple (period-1) limit cycle at the onset of impacting, but the switching mechanism may also play a role. At higher flow velocities, a subcritical bifurcation of a period-1 orbit leads to type I intermittency. For a high-dimensional system, two mechanisms leading to chaos are identified. At the onset of impacting, chaos is via the switching mechanism; at the higher flow velocities, similarly to the 2 d.o.f. system, type I intermittency results, albeit from the destabilization of a period-2 orbit. The baker's transformation is shown to make some qualitative predictions of the dynamical behaviour of the reduced Poincare map.
15 citations
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TL;DR: In this article, simple dissipative dynamical systems exhibiting a transition from a stable periodic behavior to a chaotic one were studied, where the inverse coherence time grows continuously from zero to zero due to the random occurrence of widely separated bursts in the time record.
Abstract: We study some simple dissipative dynamical systems exhibiting a transition from a stable periodic behavior to a chaotic one. At that transition, the inverse coherence time grows continuously from zero due to the random occurrence of widely separated bursts in the time record.
1,753 citations
TL;DR: In this article, a single-degree of freedom non-linear oscillator is considered and the nonlinearity is in the restoring force and is piecewise linear with a single change in slope.
802 citations
TL;DR: Forced vibrations of an elastic beam with non-linear boundary conditions are shown to exhibit chaotic behavior of the strange attractor type for a sinusoidal input force as mentioned in this paper, where the beam is clamped at one end, and the other end is pinned for the tip displacement less than some fixed value and is free for displacements greater than this value.
Abstract: Forced vibrations of an elastic beam with non-linear boundary conditions are shown to exhibit chaotic behavior of the strange attractor type for a sinusoidal input force The beam is clamped at one end, and the other end is pinned for the tip displacement less than some fixed value and is free for displacements greater than this value The stiffness of the beam has the properties of a bi-linear spring The results may be typical of a class of mechanical oscillators with play or amplitude constraining stops Subharmonic oscillations are found to be characteristic of these types of motions For certain values of forcing frequency and amplitude the periodic motion becomes unstable and nonperiodic bounded vibrations result These chaotic motions have a narrow band spectrum of frequency components near the subharmonic frequencies Digital simulation of a single mode mathematical model of the beam using a Runge-Kutta algorithm is shown to give results qualitatively similar to experimental observations
225 citations
TL;DR: In this article, the fluid-force coefficients for a row of cylinders and a square array are determined from available experimental data and critical flow velocities are calculated as a function of system parameters.
Abstract: The fluid-force coefficients for a row of cylinders and a square array are determined from available experimental data and critical flow velocities are calculated as a function of system parameters. Experimental data for critical flow velocities are found to be in good agreement with the analytical results. It is concluded that different stability criteria have to be utilized in different parameter ranges because of different instability mechanisms. 25 refs.
101 citations