Vibration of Tube Bundles Subjected to Two-Phase Cross-Flow

1985 ◽  
Vol 107 (4) ◽  
pp. 335-343 ◽  
Author(s):  
M. J. Pettigrew ◽  
J. H. Tromp ◽  
J. Mastorakos
Keyword(s):  
Heat Exchangers ◽  
Tube Bundle ◽  
Cross Flow ◽  
Elastic Instability ◽  
Steam Generators ◽  
Two Phase ◽  
Vibration Excitation ◽  
Mass Fluxes ◽  
Excitation Mechanisms ◽  
Shell And Tube

Two-phase cross-flow exists in many shell-and-tube heat exchangers such as condensers, reboilers and nuclear steam generators. Thus we are conducting a comprehensive program to study tube bundle vibrations subjected to two-phase cross-flow. This paper presents the results of experiments on a normal-triangular and a normal-square tube bundle, both of p/d = 1.47. The bundles were subjected to air-water mixtures to simulate realistic vapor qualities and mass fluxes. Vibration excitation mechanisms were deduced from vibration response measurements. Results on damping, hydrodynamic mass, fluid-elastic instability and random turbulence excitation in two-phase cross-flow are presented.

The Effects of Bundle Geometry on Heat Exchanger Tube Vibration in Two-Phase Cross Flow

2001 ◽  
Vol 123 (4) ◽  
pp. 414-420 ◽  
Author(s):  
M. J. Pettigrew ◽  
C. E. Taylor ◽  
B. S. Kim
Keyword(s):  
Heat Exchangers ◽  
Tube Bundle ◽  
Cross Flow ◽  
Heat Exchanger Tube ◽  
Two Phase ◽  
Mass Fluxes ◽  
Excitation Mechanisms ◽  
Series Of Experiments ◽  
Shell And Tube ◽  
Exchanger Tube

Many shell-and-tube heat exchangers operate in two-phase flows. This paper presents the results of a series of experiments done on tube bundles of different geometries subjected to two-phase cross flow simulated by air-water mixtures. Normal (30 deg) and rotated (60 deg) triangular, and normal (90 deg) and rotated (45 deg) square tube bundle configurations of pitch-to-diameter ratio of 1.2 to 1.5 were tested over a range of mass fluxes from 0 to 1000 kg/(m2s) and void fraction from 0 to 100 percent. The effects of tube bundle geometry on vibration excitation mechanisms such as fluidelastic instability and random turbulence, and on dynamic parameters such as damping and hydrodynamic mass are discussed.

Modeling and Simulation of Cross-Flow Induced Vibrations in Tube Bundles Using Bondgraph Approach

2006 ◽  
Author(s):  
M. Afzaal Malik ◽  
Badar Rashid ◽  
M. Anwar Khan ◽  
Khawaja Sajid Bashir ◽  
Shahab Khushnood
Keyword(s):  
Research Work ◽  
Cross Flow ◽  
Acoustic Resonance ◽  
Elastic Instability ◽  
Steam Generators ◽  
Two Phase ◽  
Considerable Research ◽  
Tube Bundles ◽  
Flow Induced Vibrations ◽  
Excitation Mechanisms

A considerable research has been carried out in the field of Cross-Flow Induced Vibrations (CFIV) in tube bundles of process exchangers and nuclear steam generators. Various excitation mechanisms such as vortex shedding, turbulent buffeting, fluid-elastic instability and acoustic resonance and other parameters like natural frequencies, damping, wear work rates at the loose tube supports and various geometric tube arrangements have been the focus in single and two-phase cross-flow. In the current research work, CFIV has been studied by using Bondgraph approach. The Bondgraph models have been subjected to simulation using the software (20-SIM). Results obtained have shown a strong usefulness of Bondgraph approach to complex CFIV systems.

Drag Coefficient and Two-Phase Friction Multiplier on Tube Bundles Subjected to Two-Phase Cross-Flow

2012 ◽  
Vol 135 (1) ◽  
Author(s):  
W. G. Sim ◽  
Njuki W. Mureithi
Keyword(s):  
Drag Coefficient ◽  
Void Fraction ◽  
Euler Number ◽  
Tube Bundle ◽  
Cross Flow ◽  
Water Mixture ◽  
Duct Flow ◽  
Two Phase ◽  
Mass Fluxes ◽  
Wide Range

An approximate analytical model, to predict the drag coefficient on a cylinder and the two-phase Euler number for upward two-phase cross-flow through horizontal bundles, has been developed. To verify the model, two sets of experiments were performed with an air–water mixture for a range of pitch mass fluxes and void fractions. The experiments were undertaken using a rotated triangular (RT) array of cylinders having a pitch-to-diameter ratio of 1.5 and cylinder diameter 38 mm. The void fraction model proposed by Feenstra et al. was used to estimate the void fraction of the flow within the tube bundle. An important variable for drag coefficient estimation is the two-phase friction multiplier. A new drag coefficient model has been developed, based on the single-phase flow Euler number formulation proposed by Zukauskas et al. and the two-phase friction multiplier in duct flow formulated by various researchers. The present model is developed considering the Euler number formulation by Zukauskas et al. as well as existing two-phase friction multiplier models. It is found that Marchaterre's model for two-phase friction multiplier is applicable to air–water mixtures. The analytical results agree reasonably well with experimental drag coefficients and Euler numbers in air–water mixtures for a sufficiently wide range of pitch mass fluxes and qualities. This model will allow researchers to provide analytical estimates of the drag coefficient, which is related to two-phase damping.

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.

Fluidelastic Instability and Periodic Fluid Forces in a Normal Triangular Tube Bundle Subjected to Air-Water Flow

2010 ◽  
Author(s):  
G. Ricciardi ◽  
M. J. Pettigrew ◽  
N. W. Mureithi
Keyword(s):  
Two Phase Flow ◽  
Tube Bundle ◽  
Fatigue Cracks ◽  
Cross Flow ◽  
Fretting Wear ◽  
Phase Flow ◽  
Steam Generators ◽  
Two Phase ◽  
Fluid Forces ◽  
Void Fractions

Two-phase flow in power plant steam generators can induce tube vibrations, which may cause fretting-wear and even fatigue cracks. It is therefore important to understand the relevant two-phase flow-induced vibration mechanisms. Fluidelastic instabilities in cross-flow are known to cause the most severe vibration response in the U-bend region of steam generators. This paper presents test results of the vibration of a normal triangular tube bundle subjected to air-water cross-flow. The test section presents 31 flexible tubes. The pitch-to-diameter ratio of the bundle is 1.5, and the tube diameter is 38 mm. Tubes were flexible in the lift direction. Seven tubes were instrumented with strain gauges to measure their displacements. A broad range of void fractions (from 10% to 90%) and fluid velocities (up to 13 m/s) were tested. Fluidelastic instabilities were observed for void fractions between 10% and 60%. Periodic fluid forces were also observed. The results are compared with those obtained with the rotated triangular tube bundle, showing that the normal triangular configuration is more stable than the rotated triangular configuration.

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.

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.

Effect of Angle of Attack on Fluidelastic Instability of a Rotated Triangular Tube Bundle

2007 ◽  
Author(s):  
A. Khalvatti ◽  
N. W. Mureithi ◽  
M. J. Pettigrew
Keyword(s):  
Hydraulic Resistance ◽  
Tube Bundle ◽  
Angle Of Attack ◽  
Cross Flow ◽  
Point Of View ◽  
Steam Generators ◽  
Fluidelastic Instability ◽  
Shell And Tube ◽  
The Stability ◽  
Resistance Forces

In the operation of shell-and-tube heat exchangers, vibration of the tubes can be induced by fluid flowing over the tube array in cross flow. The region of concern in Steam Generators (SG) is the upper most U-bend region where the flow crosses a large number of tubes which can cause significant hydraulic resistance. This hydraulic resistance forces the flow to change direction. From a fluidelastic instability point of view, the tube bundle is excited by oblique cross flow. The purpose of this paper is to examine the instability phenomena in a rotated triangular tube bundle subjected to oblique single phase cross flow. In this present work tests are conducted in a wind tunnel on a rotated triangle tube array. Fluidelastic instability results are in agreement with what was expected. The results show that fluidelastic instability is strongly dependent on the angle of attack. The results also show that, generally, the elimination of bundle flexibility in the direction transverse to the flow, greatly affects the stability behavior of the array.

Two-Phase Flow-Induced Vibration: An Overview (Survey Paper)

1994 ◽  
Vol 116 (3) ◽  
pp. 233-253 ◽  
Author(s):  
M. J. Pettigrew ◽  
C. E. Taylor
Keyword(s):  
Two Phase Flow ◽  
Cross Flow ◽  
Axial Flow ◽  
Random Excitation ◽  
Phase Flow ◽  
Flow Induced Vibration ◽  
Two Phase ◽  
Vibration Excitation ◽  
Fluidelastic Instability ◽  
Excitation Mechanisms

Two-phase flow exists in many industrial components. To avoid costly vibration problems, sound technology in the area of two-phase flow-induced vibration is required. This paper is an overview of the principal mechanisms governing vibration in two-phase flow. Dynamic parameters such as hydrodynamic mass and damping are discussed. Vibration excitation mechanisms in axial flow are outlined. These include fluidelastic instability, phase-change noise, and random excitation. Vibration excitation mechanisms in cross-flow, such as fluidelastic instability, periodic wake shedding, and random excitation, are reviewed.

A numerical study of heat transfer in the in-line tube bundle under pulsating fluid flow conditions

Vestnik IGEU ◽  
2019 ◽  
pp. 12-21
Author(s):  
A.I. Khaibullina ◽  
A.R. Khairullin
Keyword(s):  
Heat Transfer ◽  
Heat Exchangers ◽  
Numerical Study ◽  
Tube Bundle ◽  
Cross Flow ◽  
Pulsating Flow ◽  
Operating Parameters ◽  
Flow Conditions ◽  
Study Results ◽  
Shell And Tube

Shell-and-tube heat exchangers are widely used in different industries. Even a small increase in the efficien-cy of shell-and-tube heat exchangers can lead to significant energy savings. One of the ways to improve the efficiency of shell-and-tube heat exchangers is the use of pulsating flows for the enhancement of heat ex-change. Despite the fact that heat transfer in the tube bundle cross flow in steady-state conditions has been studied quite well, there is limited data on heat transfer in pulsating flow, which means that the problem of finding regularities of heat transfer with pulsating flows in tube bundles is still important. The work employs the incompressible Reynolds averaged Naviere-Stokes (URANS) equations and the continuity equation. Heat transfer is described by the convective heat transfer (Fourier-Kirchhoff) equation. The calculations are performed using Ansys Fluent. A numerical study has been conducted of the effects of forced asymmet-rical pulsating flow on heat exchange in in-line tube bundle cross-flow conditions. In the numerical experi-ment the Reynolds number Re ranged from 1000 to 2000, the relative pulsating amplitude A/D – from 1 to 2, the Strouhal number Sh – from 0,77 to 1,51, the Prandtl number and the duty cycle had fixed values: Pr = 7,2,  = 0,25. The relative transverse and longitudinal pitch was s1,2/D = 1,3. It has been found that pulsating flows lead to the enhancement of heat transfer in the whole range of the studied operating parameters. An increase in A/D and Sh leads to bigger Nusselt number Nu. An increase in the Re number leads to a de-crease in the Nu ratio in pulsating and steady flow conditions. The general correlation obtained based on the numerical study results can be used to predict heat transfer in a pulsating flow in the range of the studied geometric and operating parameters. More research is needed to predict heat transfer in a wider range of operating parameters and with other tube bundle configurations.

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