Motion-Dependent Fluid Force Coefficients for Tube Arrays in Crossflow
01 Nov 2001-Journal of Pressure Vessel Technology-transactions of The Asme (American Society of Mechanical Engineers)-Vol. 123, Iss: 4, pp 429-436
TL;DR: This paper presents several series of experiments that measure motion-dependent fluid forces for various tube arrays and obtained fluid damping and stiffness coefficients based on the unsteady flow theory as a function of reduced flow velocity, excitation amplitude, and Reynolds number.
Abstract: Fluidelastic instability of tube arrays in crossflow is interesting academically and important in steam generators and heat exchangers. The key elements necessary to accurately predict fluidelastic instability of tube arrays in crossflow are motion-dependent fluid force coefficients. This paper presents several series of experiments that measure motion-dependent fluid forces for various tube arrays. Fluid damping and stiffness coefficients based on the unsteady flow theory were obtained as a function of reduced flow velocity, excitation amplitude, and Reynolds number, and the characteristics of motion-dependent fluid force coefficients were applied to provide some additional insights into fluidelastic instability.
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TL;DR: In this paper, experiments were carried out with air-water and steam-water cross-flow over horizontal tubes, and it was found that fully flexible arrays become unstable at a lower flow velocity when compared to a single flexible tube surrounded by rigid tubes.
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TL;DR: In this article, a coupling of the unsteady flow model (UFM) with computational fluid dynamics (CFD) was proposed to calculate the stability map for a given tube array.
Abstract: This study investigates unsteady flow in tube bundles and fluid forces, which can lead to large tube vibration amplitudes, in particular, amplitudes associated with fluidelastic instability (FEI). The fluidelastic forces are approximated by the coupling of the unsteady flow model (UFM) with computational fluid dynamics (CFD). The CFD model employed solves the Reynolds averaged Navier-Stokes equations for unsteady turbulent flow and is cast in an arbitrary Lagrangian-Eulerian form to handle any motion associated with tubes. The CFD solution provides time domain forces that are used to calculate added damping and stiffness coefficients employed with the UFM. The investigation demonstrates that the UFM utilized in conjunction with CFD is a viable approach for calculating the stability map for a given tube array. The FEI was predicted for in-line square and normal triangle tube arrays over a mass damping parameter range of 0.1-100. The effect of the P/d ratio and the Reynolds number on the FEI threshold was also investigated.
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TL;DR: In this article, the effects of wavy cylindrical tubes in a staggered heat exchanger tube bundle were investigated using the large eddy simulation (LES) technique, and the results showed that the mean velocity distributions and turbulence intensity were in good agreement with the LDA measurements.
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TL;DR: In this paper, the surface vorticity method (SVM) and a fluid-structure interaction model incorporating the effects of cylinder motions and displacements is used to simulate the vortex-induced vibration of cylinder arrays at sub-critical Reynolds numbers.
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TL;DR: In this paper, the interaction between fluidelastic instability and acoustic resonance in a triangular tube array has been quantified, although no physical mechanism was identified, and the effect of acoustic resonance on the time delay between tube motion and the resultant flow reorganisation close to the measurement cylinder was examined.
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References
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01 Jan 1977TL;DR: In this paper, the authors focus on applications for offshore platforms and piping; wind-induced vibration of buildings, bridges, and towers; and acoustic and mechanical vibration of heat exchangers, power lines, and process ducting.
Abstract: This book focuses on applications for offshore platforms and piping; wind-induced vibration of buildings, bridges, and towers; and acoustic and mechanical vibration of heat exchangers, power lines, and process ducting. Numerous examples drive home the reality of the practical problems encountered here. More than 200 figures and 20 tables complement the text by providing such data as damping factors, lift coefficients, and the formulas needed to apply practical methods directly to a wide range of structures, from heat exchangers to hypersonic aircraft. Devoted to the analysis and prediction of flow-induced vibrations, this volume will prove of immense interest to mechanical, civil, nuclear, marine, structural, and electrical engineers; physicists, designers, and naval architects; and people working in the construction and petroleum industries, power plants, power transmission, ship building, nuclear power, energy production, and defense engineering.
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TL;DR: In this paper, the state of understanding of the cross flow excitation mechanisms and design guidelines for tube-and-shell heat exchangers are reviewed and the research needs in this field are discussed.
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TL;DR: In this article, the critical velocities of cylinders supported by elastic spars were calculated by using the measured unsteady fluid dynamic forces, which are induced by the vibrating cylinders.
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TL;DR: In this paper, a simple theoretical model was developed from first principles for the fluidelastic instability in heat exchanger tube bundles, and a series of experiments were conducted to verify the basic assumption that only a single tube need be modeled in a flow channel which preserves the basic geometry of the array.
Abstract: A simple theoretical model has been developed from first principles for the fluidelastic instability in heat exchanger tube bundles. A series of experiments were conducted to verify the basic assumption that only a single tube need be modeled in a flow channel which preserves the basic geometry of the array. The mechanism of instability is found to be one of flow redistribution due to tube motion and a phase lag resulting from fluid inertia. Quite good agreement is found with available experimental data for a parallel triangular array without the need for empirical fluid force coefficients. The model includes the effects of tube array pattern and pitch.
131Â citations