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.

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.

Fluid-Elastic Instability of Normal Square Tube Bundles in Two-Phase Cross Flow

2010 ◽  
Author(s):  
Woo Gun Sim ◽  
Mi Yeon Park
Keyword(s):  
Heat Exchanger ◽  
Flow Velocity ◽  
Dynamic Instability ◽  
Cross Flow ◽  
Elastic Instability ◽  
Two Phase ◽  
Critical Flow Velocity ◽  
Tube Heat Exchanger ◽  
Tube Bundles ◽  
Square Array

Some knowledge on damping and fluid-elastic instability is necessary to avoid flow-induced-vibration problems in shell and tube heat exchanger such as steam generator. Fluid-elastic instability is the most important vibration excitation mechanism for heat exchanger tube bundles subjected to the cross flow. Experiments have been performed to investigate fluid-elastic instability of normal square tube bundles, subjected to two-phase cross flow. The test section consists of cantilevered flexible cylinder(s) and rigid cylinders of normal square array. From a practical design point of view, fluid-elastic instability may be expressed simply in terms of dimensionless flow velocity and dimensionless mass-damping parameter. For dynamic instability of cylinder rows, added mass, damping and critical flow velocity are evaluated. The Fluid-elastic instability coefficient is calculated and then compared to existing results given for tube bundles in normal square array.

Vibration of Tube Bundles in Two-Phase Cross-Flow: Part 3—Turbulence-Induced Excitation

1989 ◽  
Vol 111 (4) ◽  
pp. 488-500 ◽  
Author(s):  
C. E. Taylor ◽  
I. G. Currie ◽  
M. J. Pettigrew ◽  
B. S. Kim
Keyword(s):  
Void Fraction ◽  
Tube Bundle ◽  
Cross Flow ◽  
Vibration Response ◽  
Experimental Program ◽  
Two Phase ◽  
Design Guideline ◽  
Tube Bundles ◽  
Vibration Responses ◽  
Flow Part

An extensive experimental program was carried out to study the vibration behavior of tube bundles subjected to two-phase cross-flow. Turbulence-induced excitation is discussed in Part 3 of this series of three papers. Random vibration response to turbulence-induced excitation is a significant vibration mechanism in heat exchanger tube bundles subjected to two-phase cross-flow. The vibration responses of centrally located tubes in four tube bundle configurations subjected to air-water cross-flow was measured. The results are presented in the form of a normalized forced-excitation spectrum which can be used as a design guideline over a void fraction range from 25 percent to 99 percent and over a practical range of flow rates. The data are further analyzed to determine the dependence of the vibration response on Reynolds number, void fraction and frequency. Measurements taken on a single tube, a row of tubes and on tubes having varying end conditions were used to assist in interpreting the bundle data.

Vibration of Tube Bundles in Two-Phase Cross-Flow: Part 1—Hydrodynamic Mass and Damping

1989 ◽  
Vol 111 (4) ◽  
pp. 466-477 ◽  
Author(s):  
M. J. Pettigrew ◽  
C. E. Taylor ◽  
B. S. Kim
Keyword(s):  
Tube Bundle ◽  
Damping Ratio ◽  
Cross Flow ◽  
Design Guidelines ◽  
Flow Induced Vibration ◽  
Two Phase ◽  
Mixture Density ◽  
Void Fractions ◽  
Mass Fluxes ◽  
Tube Bundles

Two-phase cross-flow exists in many shell-and-tube heat exchangers, such as condensers, reboilers and nuclear steam generators. An understanding of damping and of flow-induced vibration excitation mechanisms is necessary to avoid problems due to excessive tube vibration. Accordingly, we have undertaken an extensive program to study the vibration behavior of tube bundles subjected to two-phase cross-flow. In this paper we present the results of experiments on four tube bundle configurations; namely, normal triangular of pitch over diameter ratio, p/d, of 1.32 and 1.47, and parallel triangular and normal square of p/d of 1.47. The bundles were subjected to air-water mixtures to simulate realistic mass fluxes and vapor qualities corresponding to void fractions from 5 to 99 percent. Hydrodynamic mass and damping are discussed in Part 1 of this series of three papers. We found that hydrodynamic mass is roughly related to the homogeneous mixture density. The damping characteristics of all tube bundles are generally similar. Damping is maximum between 40 and 80 percent void fraction where the damping ratio reaches about 4 percent. The effect of mass flux is generally weak. Design guidelines are proposed for hydrodynamic mass and for damping.

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.

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.

A Global Model for Flow-Induced Vibration of Tube Bundles in Cross-Flow

1991 ◽  
Vol 113 (3) ◽  
pp. 446-458 ◽  
Author(s):  
S. Granger
Keyword(s):  
Tube Bundle ◽  
Damping Ratio ◽  
Cross Flow ◽  
Global Model ◽  
Stable Region ◽  
Predictive Analysis ◽  
System Response ◽  
Critical Flow Velocity ◽  
Global System ◽  
Tube Bundles

This paper presents an approximate model which can be used for predictive analysis of industrial tube bundles subjected to cross-flow. A tube bundle in cross-flow is locally approximated, in a global sense, by a single-degree-of-freedom system, called the global system. The critical flow velocity can be predicted by computing the velocity at which the damping ratio of the global system becomes zero. In the stable region, tube response amplitude can be approximated by the amplitude of the global system response. In this approach, the knowledge of four fluid force coefficients is required to solve the problem. They are determined experimentally by dynamic response measurements. The global model so defined is compared with the simplified method usually used for industrial predictive analysis purposes. It is shown that the conventional method can be considered as a particular simplified case of the present model. Practical examples concerning square-in-line tube bundles are given. They show that the first results obtained with the global model are promising.

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