scholarly journals Numerical investigation on Hopf bifurcation and post-instability of tube bundles subjected to two-phase cross-flow and loose support

2020 ◽  
Vol 143 ◽  
pp. 107459 ◽  
Author(s):  
Jiang Lai ◽  
Han Wu ◽  
Lei Sun ◽  
Lixia Gao ◽  
Pengzhou Li
Keyword(s):  
Hopf Bifurcation ◽  
Numerical Investigation ◽  
Cross Flow ◽  
Two Phase ◽  
Tube Bundles ◽  
Loose Support

Turbulence-induced vibration of tube bundles subjected to cross-flow and loose support

2021 ◽  
pp. 104601
Author(s):  
Jiang Lai ◽  
Shihao Yang ◽  
Tiancai Tan ◽  
Lixia Gao ◽  
Lei Sun ◽  
...  
Keyword(s):  
Cross Flow ◽  
Tube Bundles ◽  
Loose Support

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

A Design Guideline for Random Excitation Forces Due to Two-Phase Cross Flow in Tube Bundles

2020 ◽  
Vol 142 (6) ◽  
Author(s):  
Colette E. Taylor ◽  
Michel J. Pettigrew
Keyword(s):  
Experimental Data ◽  
Cross Flow ◽  
Random Excitation ◽  
Strain Gages ◽  
Two Phase ◽  
Design Guideline ◽  
Water Steam ◽  
Force Transducers ◽  
Tube Bundles ◽  
Reaction Forces

Abstract This paper re-examines the available experimental data to investigate the random excitation forces that affect tube bundles exposed to two-phase cross flow. Much of the experimental data generated over the past four decades have been gathered in an attempt to understand the parametric dependence of the random two-phase forces. The data include air–water, steam–water and various Freons used in a variety of test sections with either strain gages to measure the tube amplitude or force transducers to measure the reaction forces. A review of previous work in this area finds that some authors claim a strong flow regime dependence while others suggest that this dependence is weak. This work takes a detailed look at this discrepancy and finds that a single design guideline does not adequately bound all flow regimes. As a result, two dimensionless upper bounds are proposed.

Further Study of Quasiperiodic Vibration Excitation Forces in Rotated Triangular Tube Bundles Subjected to Two-Phase Cross Flow

2009 ◽  
Vol 131 (3) ◽  
Author(s):  
C. Zhang ◽  
M. J. Pettigrew ◽  
N. W. Mureithi
Keyword(s):  
Flow Velocity ◽  
Cross Flow ◽  
Fretting Wear ◽  
Force Frequency ◽  
Two Phase ◽  
Vibration Excitation ◽  
Tube Bundles ◽  
Excitation Force ◽  
Lift Forces ◽  
Drag And Lift

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 vibration excitation force measurements in tube bundles subjected to two-phase cross flow are required to understand the underlying vibration excitation mechanisms. Some of this work has already been done. Somewhat unexpected but significant quasiperiodic forces in both the drag and lift directions were measured. These forces are generally larger in the drag direction. However, the excitation force frequency is relatively low (i.e., 3–6 Hz) and not directly dependent on flow velocity in the drag direction. On the other hand, much higher frequencies (up to 16 Hz) were observed in the lift direction at the higher flow velocities. The frequency appears directly related to flow velocity in the lift direction. The present work aims at (1) providing further evidence of the quasiperiodic lift force mechanism, (2) determining the effect of cylinder position on such quasiperiodic drag and lift forces, and (3) verifying the existence of quasiperiodic drag and lift forces in a more realistic larger tube array. The program was carried out with two rotated triangular tube arrays of different width subjected to air/water flow to simulate two-phase mixtures from liquid to 95% void fraction. Both the dynamic lift and drag forces were measured with strain gauge instrumented cylinders.

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.

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.

Two-Phase Flow-Induced Vibration of Parallel Triangular Tube Arrays With Asymmetric Support Stiffness

2009 ◽  
Vol 131 (3) ◽  
Author(s):  
Paul Feenstra ◽  
David S. Weaver ◽  
Tomomichi Nakamura
Keyword(s):  
Two Phase Flow ◽  
Cross Flow ◽  
Phase Flow ◽  
Heat Exchanger Tube ◽  
Flow Induced Vibration ◽  
Two Phase ◽  
Tube Arrays ◽  
Tube Bundles ◽  
Pitch Ratio ◽  
Exchanger Tube

Laboratory experiments were conducted to determine the flow-induced vibration response and fluidelastic instability threshold of model heat exchanger tube bundles subjected to a cross-flow of refrigerant 11. Tube bundles were specially built with tubes cantilever-mounted on rectangular brass support bars so that the stiffness in the streamwise direction was about double that in the transverse direction. This was designed to simulate the tube dynamics in the U-bend region of a recirculating-type nuclear steam generator. Three model tube bundles were studied, one with a pitch ratio of 1.49 and two with a smaller pitch ratio of 1.33. The primary intent of the research was to improve our understanding of the flow-induced vibrations of heat exchanger tube arrays subjected to two-phase cross-flow. Of particular concern was to compare the effect of the asymmetric stiffness on the fluidelastic stability threshold with that of axisymmetric stiffness arrays tested most prominently in literature. The experimental results are analyzed and compared with existing data from literature using various definitions of two-phase fluid parameters. The fluidelastic stability thresholds of the present study agree well with results from previous studies for single-phase flow. In two-phase flow, the comparison of the stability data depends on the definition of two-phase flow velocity.

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