Research on Cross Flow Induced Vibration of Flexible Tube Bundle

2017 ◽  
Author(s):  
Zhipeng Feng ◽  
Wenzheng Zhang ◽  
Yixiong Zhang ◽  
Fenggang Zang ◽  
Huanhuan Qi ◽  
...  
Keyword(s):  
Critical Velocity ◽  
Dynamic Equilibrium ◽  
Tube Bundle ◽  
Lift Coefficient ◽  
Three Dimensional ◽  
Cross Flow ◽  
Nonlinear Phenomena ◽  
Flow Induced Vibration ◽  
Navier Stokes Equation ◽  
Flexible Tube

When the elastic deformation of the tube bundle is considered, the interaction between the flow field and the structure becomes more complicated. In order to investigate the flow induced vibration (FIV) problems in flexible tube bundle, a numerical model for fluid-structure interaction system was presented firstly. The unsteady three-dimensional Navier-Stokes equation and LES turbulence model were solved with the finite volume approach on structured grids combined with the technique of dynamic mesh. The dynamic equilibrium equation was discretized according to the finite element theory. The configurations considered are tubes in a cross flow. Firstly, the flow-induced vibration of a single flexible tube under uniform turbulent flow are calculated when Reynolds number is 1.35× 104. The variety trends of lift, drag, displacement, vertex shedding frequency, phase difference of tube are analyzed under different frequency ratios. The nonlinear phenomena of locked-in, phase-switch are captured successfully. Meanwhile, the limit cycle and bifurcation of lift coefficient and displacement are analyzed using trajectory, phase portrait and Poincare sections. Secondly, the mutual interaction of two in-line flexible tubes is investigated. Different behaviors, bounded by critical distances between the tubes, critical velocity, and wake vortex pattern are highlighted. Finally, four tube bundle models were established to study the effect of the number of flexible tube on the FIV characteristics. Thanks to several calculations, the critical velocity of instability vibration and the effect of tube bundle configurations on fluid forces and dynamics were obtained successfully. It is therefore expected that further calculations, with model refinements and other validation studies, will bring valuable informations about bundle stability. Further comparisons with experiment are necessary to validate the behavior of the method in this configuration.

Vortex-Induced Vibration Characteristics for a Three Dimensional Flexible Tube

2016 ◽  
Author(s):  
Zhipeng Feng ◽  
Fenggang Zang ◽  
Yixiong Zhang
Keyword(s):  
Dynamic Behavior ◽  
Dynamic Equilibrium ◽  
Lateral Displacement ◽  
Lift Coefficient ◽  
Three Dimensional ◽  
High Mass ◽  
Lower Branch ◽  
Vortex Induced Vibration ◽  
Flexible Tube ◽  
Lock In

In order to study the vortex-induced vibration, the three-dimensional unsteady, viscous, incompressible Navier-Stokes equation and LES turbulence model are solved with the finite volume approach, and the dynamic equilibrium equations are discretized by the finite element theory. A three-dimensional numerical model for flexible tube vibration induced by cross flow is proposed. The model realized the fluid-structure interaction with solving the fluid flow and the structure vibration simultaneously. Based on this model, the dynamic behavior and response characteristic of the tube are investigated. Meanwhile, the limit cycle and bifurcation of lift coefficient and displacement are analyzed. Amplitude response, trajectory, phase difference, fluid force coefficient and vortex shedding frequency are obtained. The results reveal that, a quasi-upper branch is found in the present fluid-flexible tube coupling system with high mass-damping and low mass ratio. The three-dimensional flexible tube has a broader synchronization range and the amplitude is higher than elastically mounted two-dimensional rigid tube. In the quasi-upper branch and lower branch regime, the “lock-in” begins. In quasi-upper branch, the lateral amplitude increases with reduced velocity increasing. While in lower branch, the amplitude keeps almost constant. The drag force reaches its peak value before lift. The lift coefficient reaches its maximum value at the switch from initial branch to quasi-upper branch. The phase angle reaches zero under “lock-in” and the dynamic behavior is a periodic motion. There is no bifurcation of lift coefficient and lateral displacement occurred in three dimensional flexible tube submitted to uniform turbulent flow.

Vibration Excitation Forces in a Rotated Triangular Tube Bundle Subjected to Two-Phase Cross Flow

2010 ◽  
Author(s):  
H. Senez ◽  
N. W. Mureithi ◽  
M. J. Pettigrew
Keyword(s):  
Steam Generator ◽  
Tube Bundle ◽  
Cross Flow ◽  
Fretting Wear ◽  
Experimental Program ◽  
Phase Flow ◽  
Flow Induced Vibration ◽  
Two Phase ◽  
Fluid Forces ◽  
Vibration Excitation

Two-phase cross flow exists in many shell-and-tube heat exchangers. Flow-induced vibration excitation forces can cause tube motion that will result in long-term fretting wear or fatigue. Detailed flow and vibration excitation force measurements in tube bundles subjected to two-phase cross flow are required to understand the underlying vibration excitation mechanisms. Studies on this subject have already been done, providing results on flow regimes, fluidelastic instabilities, and turbulence-induced vibration. The spectrum of turbulence-induced forces has usually been expected to be similar to that in single-phase flow. However, a recent study, using tubes with a diameter larger than that in a real steam generator, showed the existence of significant quasi-periodic forces in two-phase flow. An experimental program was undertaken with a rotated-triangular array of cylinders subjected to air-water cross-flow, to simulate two-phase mixtures. The tube bundle here has the same geometry as that of a real steam generator. The quasi-periodic forces have now also been observed in this tube bundle. The present work aims to understand turbulence-induced forces acting on the tube bundle, providing results on drag and lift force spectra and their behaviour according to flow parameters, and describing their correlations. Detailed experimental test results are presented in this paper. Comparison is also made with previous measurements with larger diameter tubes. The present results suggest that quasi-periodic fluid forces are not uncommon in tube arrays subjected to two-phase cross-flow.

Modeling and Simulation of Cross-Flow Induced Vibration in a Multi-Span Tube Bundle

2004 ◽  
Author(s):  
Shahab Khushnood ◽  
Zaffar M. Khan ◽  
M. Afzaal Malik ◽  
Zafarullah Koreshi ◽  
Mahmood Anwar Khan
Keyword(s):  
Heat Exchanger ◽  
Tube Bundle ◽  
Cross Flow ◽  
Fatigue Cracking ◽  
Acoustic Resonance ◽  
Computer Code ◽  
Variable Geometry ◽  
Flow Induced Vibration ◽  
Two Phase ◽  
Tube Bundles

Flow-induced vibration in steam generator and heat exchanger tube bundles has been a source of major concern in nuclear and process industry. Tubes in a bundle are the most flexible components of the assembly. Flow induced vibration mechanisms, like fluid-elastic instability, vortex shedding, turbulence induced excitation and acoustic resonance results in failure due to mechanical wear, fretting and fatigue cracking. The general trend in heat exchanger design is towards larger exchangers with increased shell side velocities. Costly plant shutdowns have been the motivation for research in the area of cross-flow induced vibration in steam generators and process exchangers. The current paper focuses on the development of a computer code (FIVPAK) for the design (natural frequencies, variable geometry, tube pitch & pattern, mass damping parameter, reduced velocity, strouhal and damage numbers, added mass, wear work rates, void fraction for two-phase, turbulence and acoustic considerations etc.) of tube bundles with respect to cross flow-induced vibration. The code has been validated against Tubular Exchanger Manufacturers (TEMA), Flow-Induced Vibration code (FIV), and results on an actual variable geometry exchanger, specially manufactured to simulate real systems. The proposed code is expected to prove a useful tool in designing a tube bundle and to evaluate the performance of an existing system.

Investigations of In-Plane Fluidelastic Instability in a Multi-Span U-Bend Tube Bundle: Tests in Air Flow

2017 ◽  
Author(s):  
Paul Feenstra ◽  
Teguewinde Sawadogo ◽  
Bruce Smith ◽  
Victor Janzen ◽  
Helen Cothron
Keyword(s):  
Steam Generator ◽  
Tube Bundle ◽  
Air Flow ◽  
Cross Flow ◽  
Test Rig ◽  
Flow Induced Vibration ◽  
Two Phase ◽  
Fluidelastic Instability ◽  
Air Blower ◽  
R 134A

The tubes in the U-bend region of a recirculating type of nuclear steam generator are subjected to cross-flow of a two-phase mixture of steam and water. There is a concern that these tubes may experience flow-induced vibration, including the damaging effects of fluidelastic instability. This paper presents an update and results from a series of flow-induced vibration experiments performed by Canadian Nuclear Laboratories for the Electric Power Research Institute (EPRI) using the Multi-Span U-Bend test rig. In the present experiments, the main focus was to investigate fluidelastic instability of the U-tubes subjected to a cross-flow of air. The tube bundle is made of 22 U-tubes of 0.5 in (12.7 mm) diameter, arranged in a rotated triangular configuration with a pitch-over-diameter ratio of 1.5. The test rig could be equipped with variable clearance flat bar supports at two different locations to investigate a variety of tube and support configurations. The primary purpose of the overall project is to study the effect of flat bar supports on ‘in plane’ (‘streamwise’) instability in a U-tube bundle with realistic tube-to-support clearances or preloads, and eventually in two-phase flow conditions. Initially, the test rig was designed for tests in air-flow using an industrial air blower. Tests with two-phase Freon refrigerant (R-134a) will follow. This paper describes the test rig, experimental setup, and the challenges presented by simulating an accurate representation of current steam generator designs. Results from the first series of tests in air flow are described.

Vibration of Tube Bundles in Two-Phase Cross-Flow: Part 2—Fluid-Elastic Instability

1989 ◽  
Vol 111 (4) ◽  
pp. 478-487 ◽  
Author(s):  
M. J. Pettigrew ◽  
J. H. Tromp ◽  
C. E. Taylor ◽  
B. S. Kim
Keyword(s):  
Tube Bundle ◽  
Cross Flow ◽  
Design Guidelines ◽  
Experimental Program ◽  
Elastic Instability ◽  
Two Phase ◽  
Critical Flow Velocity ◽  
Flexible Tube ◽  
Elastic Instabilities ◽  
Tube Bundles

An extensive experimental program was carried out to study the vibration behavior of tube bundles subjected to two-phase cross-flow. Fluid-elastic instability is discussed in Part 2 of this series of three papers. Four tube bundle configurations were subjected to increasing flow up to the onset of fluid-elastic instability. The tests were done on bundles with all-flexible tubes and on bundles with one flexible tube surrounded by rigid tubes. Fluid-elastic instabilities have been observed for all tube bundles and all flow conditions. The critical flow velocity for fluid-elastic instability is significantly lower for the all-flexible tube bundles. The fluid-elastic instability behavior is different for intermittent flows than for continuous flow regimes such as bubbly or froth flows. For continuous flows, the observed instabilities satisfy the relationship V/fd = K(2πζm/ρd2)0.5 in which the minimum instability factor K was found to be around 4 for bundles of p/d = 1.47 and significantly less for p/d = 1.32. Design guidelines are recommended to avoid fluid-elastic instabilities in two-phase cross-flows.

Three Dimensional Numerical Modelling of Staggered Tube Bundle Turbulent Crossflow in Duct

2005 ◽  
Author(s):  
Ahad Ramezanpour ◽  
Hassan Shirvani ◽  
Ramin Rahmani ◽  
Iraj Mirzaee
Keyword(s):  
Nusselt Number ◽  
Numerical Study ◽  
Tube Bundle ◽  
Three Dimensional ◽  
Cross Flow ◽  
Reynolds Numbers ◽  
Wall Function ◽  
Flat Plates ◽  
Geometrical Characteristics ◽  
Commercial Code

A numerical study has been conducted to investigate the three dimensional (3D) staggered tube bundle turbulent cross flow confined between two parallel flat plates using RNG k-ε model and standard wall function utilizing commercial code FLUENT. The maximum Reynolds numbers of 1000, 5000, and 50000 and the distance between plates of H = 3, 5, 10, 15, and 20 mm have been considered. The arrangement of the staggered tube bundle is fix with geometrical characteristics of Sn/D = 1.5 and Sp/D = 1.2 which has been found optimum in previous two-dimensional studies. The constant temperature of 360K on tubes, constant inlet flow and plates’ temperature of 300K have been set as the boundary conditions. The global Nusselt number, friction factor for the dissimilar Reynolds numbers, distance between plates, local Nusselt number and different angles on first and third tubes have been evaluated.

Mesh Shape Preservation for Flow-Induced Vibration Problems

2002 ◽  
Author(s):  
R. M. C. So ◽  
Y. Liu ◽  
Y. G. Lai
Keyword(s):  
Numerical Technique ◽  
Three Dimensional ◽  
Cross Flow ◽  
Physical Space ◽  
Shape Preservation ◽  
Structural Vibration ◽  
Flow Induced Vibration ◽  
Time Step ◽  
Dimensional Flow ◽  
Vibration Problems

This paper describes a numerical technique that can prevent the mesh from severe distortion in flow-induced vibration calculations. An orthogonal transformed space that is related to the physical space through a Laplacian equation is introduced. At each time step, the mesh may deform significantly in the physical space due to structural vibration, but the mesh nodal value in the transformed space remains constant. As long as the coordinates in the physical space can be adjusted to render the transformed space independent of time, the mesh shape in the physical space is preserved, even though the mesh area may enlarge or reduce significantly. For simplicity, a two-dimensional flow-induced vibration problem is used to illustrate this method. Two side-by-side elastic cylinders in a cross flow are considered. The Reynolds number is fixed at 200 so that a laminar wake is still available. The mass ratio is chosen to be small so that large displacements of the cylinders can be realized. The predictions with and without mesh preservation are compared. The difference between the two results could be as large as 25% in the prediction of the mean transverse displacements of the cylinders. The method could be extended to three-dimensional flow-induced vibration problems without much difficulty.

Flow-Induced Vibration of Cross-Shaped Tube Bundle: The Effect of Tube Bundle Arrangement

2003 ◽  
Author(s):  
Fumio Inada ◽  
Takashi Nishihara ◽  
Akira Yasuo ◽  
Ryo Morita ◽  
Akihiro Sakashita ◽  
...  
Keyword(s):  
Correlation Length ◽  
Random Vibration ◽  
Tube Bundle ◽  
Cross Flow ◽  
Flow Induced Vibration ◽  
Power Spectral ◽  
Shaped Tube ◽  
Excited Vibration ◽  
Power Spectral Densities ◽  
Staggered Arrangement

A cross-shaped tube bundle is proposed for the lower plenum structure in the next-generation LWR. The effect of tube bundle arrangement on the flow-induced vibration characteristics of the cross-shaped tube bundle in cross flow was considered experimentally. Regarding random vibration, the power spectral density of the fluid force of the staggered arrangement as well as the correlation length was measured and those of the normal arrangement were compared with those of the staggered arrangement. Regarding self-excited vibration, vibration response was compared. The trend of the power spectral densities, correlation length, and the critical velocity of the normal arrangement were similar to those of the staggered arrangement.

Experimental study on cross flow induced vibration response of four-span straight tube bundle with TSP or AVB supports

2019 ◽  
Vol 349 ◽  
pp. 8-19 ◽  
Author(s):  
Zhengting Quan ◽  
Kefeng Zhang ◽  
Zhenqin Xiong ◽  
Hongbiao Zu ◽  
Hanyang Gu ◽  
...  
Keyword(s):  
Experimental Study ◽  
Tube Bundle ◽  
Cross Flow ◽  
Vibration Response ◽  
Straight Tube ◽  
Flow Induced Vibration
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