Numerical Prediction of Fluid-Elastic Instability in Normal Triangular Tube Bundles With Multiple Flexible Circular Cylinders

2013 ◽  
Vol 135 (3) ◽  
Author(s):  
Hamed Houri Jafari ◽  
Behzad Ghadiri Dehkordi
Keyword(s):  
Tube Bundle ◽  
Equations Of Motion ◽  
Cross Flow ◽  
Structural Equations ◽  
Circular Cylinders ◽  
Staggered Grid ◽  
Elastic Instability ◽  
Time Step ◽  
Tube Bundles ◽  
Flow Through

Prediction of fluid-elastic instability onset is a great matter of importance in designing cross-flow heat exchangers from the perspective of vibration. In the present paper, the threshold of fluid-elastic instability has been numerically predicted by the simulation of incompressible, unsteady, and turbulent cross flow through a tube bundle in a normal triangular arrangement. In the tube bundle under study, there were single or multiple flexible cylinders surrounded by rigid tubes. A finite volume solver based on a Cartesian-staggered grid was implemented. In addition, the ghost-cell method in conjunction with the great-source-term technique was employed in order to directly enforce the no-slip condition on the cylinders' boundaries. Interactions between the fluid and the structures were considered in a fully coupled manner by means of intermittence solution of the flow field and structural equations of motion in each time step of the numerical modeling algorithm. The accuracy of the solver was validated by simulation of the flow over both a rigid and a flexible circular cylinder. The results were in good agreement with the experiments reported in the literatures. Eventually, the flow through seven different flexible tube bundles was simulated. The fluid-elastic instability was predicted and analyzed by presenting the structural responses, trajectory of flexible cylinders, and critical reduced velocities.

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.

The Fluid Elastic Instability of Concentric Arrays of Tube Bundles Subjected on Cross Flow

2018 ◽  
Author(s):  
Liyan Liu ◽  
Wei Xu ◽  
Kai Guo ◽  
Zhanbin Jia ◽  
Yang Wang ◽  
...  
Keyword(s):  
Heat Exchangers ◽  
High Speed ◽  
Nuclear Power ◽  
Power Plants ◽  
Tube Bundle ◽  
Experimental Studies ◽  
Cross Flow ◽  
High Speed Photography ◽  
Elastic Instability ◽  
Tube Bundles

Concentric arrays of tube bundles are applied extensively in heat exchangers at nuclear power plants. Flow induced vibration is one of the main causes of heat exchanger failures. However, there is no corresponding standard and basic parameters in the design code of different countries for concentric arrays of tube bundles. The fluid elastic instability of this type of heat exchangers cannot be calculated, and the design criteria is lacked. In this paper, a circulating water tunnel experimental facility were set up to test the vibration characteristic of concentric arrays subjected to cross flow. A non-contact measurement method based on high-speed photography imaging technology were adopted, which improved the accuracy of the test. Three kinds of tube bundles (0-degree angle, 15-degree angle and 30-degree angle arrangement, radial/circumferential pitch being 33.6/36.4 mm) were studied. The vibration frequency, amplitude and critical velocity of the tube bundle were investigated by changing the flow velocity. Computational fluid dynamics and fluid-structure interaction method were applied to simulate the fluid elastic instability of tube bundles, that were further verified by the experiments. Meanwhile, the numerical simulation supplements the contents of the experimental studies, which is utilizable to investigate and research the fluid elastic instability. The results of this work could provide references for the design of concentric array heat exchangers.

scholarly journals Numerical Prediction of Two-Phase Flow through a Tube Bundle Based on Reduced-Order Model and a Void Fraction Correlation

Entropy ◽  
2021 ◽  
Vol 23 (10) ◽  
pp. 1355
Author(s):  
Claire Dubot ◽  
Cyrille Allery ◽  
Vincent Melot ◽  
Claudine Béghein ◽  
Mourad Oulghelou ◽  
...  
Keyword(s):  
Void Fraction ◽  
Grassmann Manifold ◽  
Tube Bundle ◽  
Cross Flow ◽  
Horizontal Tube ◽  
Phase Flow ◽  
Two Phase ◽  
Tube Bundles ◽  
Flow Through ◽  
Phase Mixture

Predicting the void fraction of a two-phase flow outside of tubes is essential to evaluate the thermohydraulic behaviour in steam generators. Indeed, it determines two-phase mixture properties and affects two-phase mixture velocity, which enable evaluating the pressure drop of the system. The two-fluid model for the numerical simulation of two-phase flows requires interaction laws between phases which are not known and/or reliable for a flow within a tube bundle. Therefore, the mixture model, for which it is easier to implement suitable correlations for tube bundles, is used. Indeed, by expressing the relative velocity as a function of slip, the void fraction model of Feenstra et al.and Hibiki et al. developed for upward cross-flow through horizontal tube bundles is introduced and compared. With the method suggested in this paper, the physical phenomena that occur in tube bundles are taken into consideration. Moreover, the tube bundle is modelled using a porous media approach where the Darcy–Forchheimer term is usually defined by correlations found in the literature. However, for some tube bundle geometries, these correlations are not available. The second goal of the paper is to quickly compute, in quasi-real-time, this term by a non-intrusive parametric reduced model based on Proper Orthogonal Decomposition. This method, named Bi-CITSGM (Bi-Calibrated Interpolation on the Tangent Subspace of the Grassmann Manifold), consists in interpolating the spatial and temporal bases by ITSGM (Interpolation on the Tangent Subspace of the Grassmann Manifold) in order to define the solution for a new parameter. The two developed methods are validated based on the experimental results obtained by Dowlati et al. for a two-phase cross-flow through a horizontal tube bundle.

Development of a Numerical Model for Quasi-Periodic Forces of Two-Phase Cross Flow in Tube Bundles

2014 ◽  
Author(s):  
Sarra Zoghlami ◽  
Cédric Béguin ◽  
Stéphane Étienne
Keyword(s):  
Numerical Model ◽  
Tube Bundle ◽  
Cross Flow ◽  
Deep Understanding ◽  
Added Mass ◽  
Dispersed Phase ◽  
Two Phase ◽  
Induced Drag ◽  
Tube Bundles ◽  
Lagrange Approach

To reduce the damage caused by induced vibrations due to two-phase cross flow on tube bundles in heat exchangers, a deep understanding of the different sources of this phenomenon is required. For this purpose, a numerical model was previously developed to simulate the quasi periodic forces on the tube bundle due to two-phase cross flow. An Euler-Lagrange approach is adopted to describe the flow. The Euler approach describes the continuous phase (liquid) using potential flow. The dispersed phase is assumed to have no interaction on liquid flow. Based on visual observation, static vortices behind the tube are introduced. The Lagrange approach describes the dispersed phase (gas). The model allows bubbles to split up or to coalesce. The forces taken into account acting on the bubbles are the buoyancy, the drag and induced drag, the added mass and induced added mass and impact force (bubble-bubble and bubble-tube). Forces taken into account acting on the tubes are impact forces and induced drag and added mass forces. This model allows us to obtain quasi periodic force on tube induced by two-phase cross flow of relative good magnitude and frequency contains. The model still needs improvement to bring us closer to experimental data of force, for example by introducing a dependency between the void ratio and the intensity of the vortex and by taking into account the bubbles deformation.

Design guidelines for fluid-elastic instability of tube bundles subjected to two-phase cross flow

2019 ◽  
Vol 20 (8) ◽  
pp. 577-589
Author(s):  
Ning Sun ◽  
Rui-jia Cheng ◽  
Ya-nan Zhang ◽  
Bao-qing Liu ◽  
Bengt Sunden
Keyword(s):  
Cross Flow ◽  
Design Guidelines ◽  
Elastic Instability ◽  
Two Phase ◽  
Tube Bundles

Experimental Investigation of Fluid-Elastic Vibration of Square Array Tube Bundle in Two Phase Flow

2019 ◽  
Author(s):  
Ryoichi Kawakami ◽  
Seinosuke Azuma ◽  
Toshifumi Nariai ◽  
Kazuo Hirota ◽  
Hideyuki Morita ◽  
...  
Keyword(s):  
Two Phase Flow ◽  
Tube Bundle ◽  
Flow Direction ◽  
Phase Flow ◽  
Elastic Instability ◽  
Steam Generators ◽  
Two Phase ◽  
Critical Flow Velocity ◽  
Tube Bundles ◽  
Square Array

Abstract The in-plane (in-flow) fluid-elastic instability (in-plane FEI) of triangular tube arrays caused tube-to-tube wear indications as observed in the U-bend regions of tube bundles of the San Onofre Unit-3 steam generators[1]. Several researches revealed that the in-plane FEI is likely to occur in a tightly packed triangular tube array under high velocity and low friction conditions, while it is not likely to occur in a square array tube bundle. In order to confirm the potential of steam-wise fluid-elastic instability of square arrays, the critical flow velocity in two-phase flow, (sulfur hexafluoride-ethanol) which simulates steam-water flow, was investigated. Two types of test rigs were prepared to confirm the effect of the tube diameter and tube pitch ratio on the critical velocity. In both rigs, vibration amplitudes were measured in both in-flow and out-of-flow directions in various flow conditions. In any case, in-flow fluid elastic instability was not detected. Based on the results of the tests, it is concluded that the flow interaction force is small for concern to occur the fluid-elastic instability in the in-flow direction of the square tube bundles of steam generators.

Fluctuating Lift Forces of the Karman Vortex Streets on Single Circular Cylinders and in Tube Bundles: Part 3—Lift Forces in Tube Bundles

1972 ◽  
Vol 94 (2) ◽  
pp. 623-628 ◽  
Author(s):  
Y. N. Chen
Keyword(s):  
Second Harmonic ◽  
Tube Bundle ◽  
Lift Coefficient ◽  
Reynolds Numbers ◽  
Circular Cylinders ◽  
Critical Flow Velocity ◽  
Pressure Drag ◽  
Tube Bundles ◽  
Karman Vortex ◽  
Lift Forces

The trend of the fluctuating lift coefficient CL and the dimensionless shedding frequency S (Strouhal number) of the vortex in tube bundles at higher Reynolds numbers R will be predicted by the course of the steady pressure drag coefficient CD at the corresponding R ranges. Furthermore, some measurements of the vortex lift forces in tube bundles will be given. It reveals that the lift force for certain small transverse tube spacings possesses a strong second harmonic. The tubes and, therefore, the transverse gas column in the tube bundle channel can be excited to vibrate in resonance either at the critical flow velocity or at its half value. Finally, the coupled vibration between the vortex shedding and the transverse gas column will be covered with some experiments.

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.

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