Study on Two-Phase Flow Behavior and Turbulent Excitation Mechanism in a U-Bend Tube-Bundle in Steam Generators Based on Air-Water Two-Phase Flow Model Tests.

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.

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

Volume 4: Fluid-Structure Interaction ◽

10.1115/pvp2019-93473 ◽

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.

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B122 Experimental study on two-phase flow behavior in horizontal tube bundle using simulated fluid

The Proceedings of the National Symposium on Power and Energy Systems ◽

10.1299/jsmepes.2012.17.63 ◽

2012 ◽

Vol 2012.17 (0) ◽

pp. 63-66

Author(s):

Atsushi ISHIKAWA ◽

Ryoji IMAI ◽

Takahiro TANAKA

Keyword(s):

Experimental Study ◽

Two Phase Flow ◽

Tube Bundle ◽

Flow Behavior ◽

Horizontal Tube ◽

Phase Flow ◽

Two Phase

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Numerical Experiment on Two-Phase Flow Behaviors in Tube Bundle Geometry for Different Mixtures

Volume 4: Fluid-Structure Interaction ◽

10.1115/pvp2017-65349 ◽

2017 ◽

Author(s):

William Benguigui ◽

Enrico Deri ◽

Jerome Lavieville ◽

Stephane Mimouni ◽

Elisabeth Longatte

Keyword(s):

Numerical Experiment ◽

Void Fraction ◽

Two Phase Flow ◽

Tube Bundle ◽

Phase Flow ◽

Steam Generators ◽

Two Phase ◽

Scale Experiment ◽

Multi Phase ◽

Two Fluid

Since steam generators are used, many experiments have been performed to understand the different phenomena appearing in them. One of the main issues to reproduce a similar flow on a reduced-scale experiment is the choice of the two-phase mixture. Air/water and boiling freon are among the most used two-phase flow mixtures. In the present document, a finite-volume CFD code dedicated to multi-phase flows based on a two-fluid approach (extended to n) is used to compare two mixtures numerically. Thanks to two experiments, an air/water horizontal channel and a freon/freon inclined tube bundle, a first part highlights the validity of the two-phase flow modeling. Then, based on inlet superficial velocities from both experiments, a numerical experiment is performed by using each mixture on the other experiment. Void fraction profiles and two-phase flow regimes are compared in order to exhibit the behaviors of both mixtures in a steam generator like tube bundle. Results turn out to provide useful information (void fraction profiles mainly) about mixture properties, and near-wall loads in the vicinity of cylinders are investigated.

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A Two-Phase Flow Approach for the Outlet of Lubricated Line Contacts

Journal of Tribology ◽

10.1115/1.4006277 ◽

2012 ◽

Vol 134 (4) ◽

Cited By ~ 9

Author(s):

V. Bruyere ◽

N. Fillot ◽

G. E. Morales-Espejel ◽

P. Vergne

Keyword(s):

Flow Model ◽

Two Phase Flow ◽

Stokes Equations ◽

Flow Behavior ◽

Diffuse Interface ◽

Fluid Distribution ◽

Phase Flow ◽

Film Rupture ◽

Two Phase ◽

Line Contacts

In the classical Reynolds equation-based modeling of lubrication, the exit area is only considered through a pressure boundary condition which fails to predict the remaining amount of lubricant on each moving surface after the film rupture. A two-phase flow model using the Navier-Stokes equations and a diffuse interface approach is developed to analyze the lubricant behavior at the exit of rolling and sliding lubricated line contacts. After physical and numerical descriptions of the two-phase flow model, results are compared with experimental data from the literature. Good agreements are found concerning pressure profiles and meniscus exit abscissas. The model is then used to study in detail the flow behavior at the exit for different surface tensions. It is shown that when surface tension effects are important, recirculation areas occur downstream the air/oil meniscus. Sliding effects on fluid distribution are then investigated. Finally, an analytical approach is proposed, as a synthesis of the numerical results.

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Comprehensive Comparisons of a Two-Phase Flow Model with a Wide Range of Conditions

Coastal Dynamics 2005 ◽

10.1061/40855(214)91 ◽

2006 ◽

Author(s):

Haijiang Liu ◽

Shinji Sato

Keyword(s):

Flow Model ◽

Two Phase Flow ◽

Phase Flow ◽

Two Phase ◽

Wide Range

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A ONE-DIMENSIONAL TWO-PHASE FLOW MODEL AND EXPERIMENTAL VALIDATION FOR A FLASHING VISCOUS LIQUID IN A SPLASH PLATE NOZZLE

Atomization and Sprays ◽

10.1615/atomizspr.2015011460 ◽

2015 ◽

Vol 25 (9) ◽

pp. 795-817 ◽

Cited By ~ 1

Author(s):

Mika P. Jarvinen ◽

A. E. P. Kankkunen ◽

R. Virtanen ◽

P. H. Miikkulainen ◽

V. P. Heikkila

Keyword(s):

Viscous Liquid ◽

Experimental Validation ◽

Flow Model ◽

Two Phase Flow ◽

Phase Flow ◽

Two Phase ◽

One Dimensional

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Status of Advanced Two-Phase Flow Model Development for SRM Chamber Flow Field and Combustion Modeling

10.21236/ada427829 ◽

2004 ◽

Author(s):

Gary Luke ◽

Mark Eagar ◽

Michael Sears ◽

Scott Felt ◽

Bob Prozan

Keyword(s):

Flow Field ◽

Flow Model ◽

Two Phase Flow ◽

Model Development ◽

Phase Flow ◽

Two Phase ◽

Combustion Modeling

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Experimental Investigation and Prediction on Pressure Drop during Flow Boiling in Horizontal Microchannels

Micromachines ◽

10.3390/mi12050510 ◽

2021 ◽

Vol 12 (5) ◽

pp. 510

Author(s):

Yan Huang ◽

Bifen Shu ◽

Shengnan Zhou ◽

Qi Shi

Keyword(s):

Pressure Drop ◽

Flow Model ◽

Two Phase Flow ◽

Flow Boiling ◽

Separated Flow ◽

Heat Fluxes ◽

Phase Flow ◽

Vapor Quality ◽

Two Phase ◽

Gas Flux

In this paper, two-phase pressure drop data were obtained for boiling in horizontal rectangular microchannels with a hydraulic diameter of 0.55 mm for R-134a over mass velocities from 790 to 1122, heat fluxes from 0 to 31.08 kW/m2 and vapor qualities from 0 to 0.25. The experimental results show that the Chisholm parameter in the separated flow model relies heavily on the vapor quality, especially in the low vapor quality region (from 0 to 0.1), where the two-phase flow pattern is mainly bubbly and slug flow. Then, the measured pressure drop data are compared with those from six separated flow models. Based on the comparison result, the superficial gas flux is introduced in this paper to consider the comprehensive influence of mass velocity and vapor quality on two-phase flow pressure drop, and a new equation for the Chisholm parameter in the separated flow model is proposed as a function of the superficial gas flux . The mean absolute error (MAE ) of the new flow correlation is 16.82%, which is significantly lower than the other correlations. Moreover, the applicability of the new expression has been verified by the experimental data in other literatures.

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