An Experimental Study About Two-Phase Damping Ratio on a Tube Bundle Subjected to Two-Phase Flow

2017 ◽  
Author(s):  
Key Sun Kim ◽  
Woo Gun Sim ◽  
Banzragch Dagdan
Keyword(s):  
Drag Force ◽  
Mass Flux ◽  
Two Phase Flow ◽  
Flow Direction ◽  
Damping Ratio ◽  
Homogeneous Model ◽  
Phase Flow ◽  
Two Phase ◽  
Phase Damping ◽  
Tube Bundles

An analytical model was developed by Sim to calculate the two-phase damping ratio for upward two-phase flow perpendicular to horizontal tube bundles. To verify the model, the present experiment is performed with a typical normal square array of cylinders subjected to the two-phase flow of air-water in the tube bundles. The diameter of cylinder is 18mm and the pitch ratio to diameter is 1.35. Using a pressure transducer and data acquisition system, pressure loss along the flow direction in the tube bundles is measured to evaluate the two-phase Euler number and the two-phase friction multiplier. The drag force along the flow direction on a tube is measured to calculate the drag coefficient and the two-phase damping ratio. The experimental results of the two-phase damping ratios are compared with the analytical results given by Sim’s model for homogeneous two-phase flow. It was found that, as increasing the mass flux, the drag force and the drag coefficients given by experimental test are close to the results calculated by the homogeneous model. As a result, the damping ratio can be evaluated by the homogeneous model for bubbly flow of sufficiently large mass flux.

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.

An Evaluation of a Two-Phase Damping Model on Tube Bundles Subjected to Two-Phase Cross Flow

2010 ◽  
Author(s):  
W. G. Sim ◽  
Njuki W. Mureithi
Keyword(s):  
Analytical Model ◽  
Mass Flux ◽  
Damping Ratio ◽  
Cross Flow ◽  
Experimental Results ◽  
Water Mixture ◽  
Two Phase ◽  
Phase Damping ◽  
Tube Bundles ◽  
Damping Model

The analytical model (Sim; 2007), to predict the two-phase damping ratio for upward cross-flow through horizontal tube bundles, has been evaluated. The damping model was formulated, based on Feenstra’s model (2000) for void fraction and various models (homogeneous, Levy, Martinelli-Nelson and Marchaterre) for two-phase friction multiplier. The analytical results of drag coefficient on a cylinder and two-phase Euler number were compared with the experimental results by Sim-Mureithi (2010). The factor, a relation between frictional pressure drop and the hydraulic drag coefficients, could be determined by considering experimental results. The two-phase damping ratios, given by the analytical model, were compared with existing experimental results. It was found that the model, based on Marchaterre’s model, is suitable for air-water mixture while the Martinelli-Nelson’s model for steam-water and Freon mixtures. The two-phase damping ratio is independent on pitch mass flux for air-water mixture, but it is more or less influenced by the mass flux for steam-water/Freon(134) mixtures. The two-phase damping ratios, given by the present model, agree well with experimental results for a sufficiently wide range of pitch mass ratio, quality and p/d ratios.

Damping of Tubes With Internal Two-Phase Flow

2006 ◽  
Author(s):  
Alexandre Gravelle ◽  
Annie Ross ◽  
Michel J. Pettigrew ◽  
Njuki W. Mureithi
Keyword(s):  
Flow Regime ◽  
Void Fraction ◽  
Two Phase Flow ◽  
Damping Ratio ◽  
Strong Dependence ◽  
Internal Flow ◽  
Piping System ◽  
Phase Flow ◽  
Two Phase ◽  
Phase Damping

Two-phase internal flow is present in many piping system components. Although two-phase damping is known to be a significant constituent of the total damping, the energy dissipation mechanisms that govern two-phase damping are not well understood. In this paper, damping of vertical clamped-clamped tubes subjected to two-phase air-water internal flow is investigated. Experimental data is reported, showing no dependence of two-phase damping on tube natural frequency, and a strong dependence on void fraction, flow velocity and flow regime. Two-phase damping increases with void fraction, reaches a maximum, and decreases beyond that point. The maximum damping ratio is roughly 3% for all flow velocities. It is reached at around 50% void fraction for high velocities, and 25% void fraction for low velocities. Data points plotted on two-phase flow pattern maps indicate that damping is greater in a bubbly flow regime than it is in a slug or churn regime. The maximum two-phase damping is reached at the highest void fraction before the transition to a slug or churn flow regime. It appears that two-phase damping may depend on the interface surface area between phases.

Investigation of Drag Force on Non-Spherical Particle in Gas-Particle Two-Phase Flow

2003 ◽  
Author(s):  
Changfu You ◽  
Haiying Qi ◽  
Xuchang Xu
Keyword(s):  
Drag Coefficient ◽  
Numerical Method ◽  
Spherical Particle ◽  
Drag Force ◽  
Two Phase Flow ◽  
Flow Direction ◽  
Phase Flow ◽  
Sphere Diameter ◽  
Computational Results ◽  
Two Phase

Research of the effect of non-spherical particle on the drag force had been carried out using numerical method. At Re<100, the flow over three different non-spherical particle (cube, cylinder and frustum) had been calculated with N-S equations. In particular, the performance of three promising correlations for the drag coefficient of the non-spherical particle had been critically examined with the computational results. The best method appears to be that of Ganser which uses the equal volume sphere diameter and sphericity of particle. Comparing the results obtained by two different cylinder’s arrangement, the axis of cylinder perpendicular to the coming flow direction and parallel to that, the divergence between them is very obvious.

A Method for Correlating the Characteristics of Centrifugal Pumps in Two-Phase Flow

1978 ◽  
Vol 100 (4) ◽  
pp. 395-409 ◽  
Author(s):  
Jaroslaw Mikielewicz ◽  
David Gordon Wilson ◽  
Tak-Chee Chan ◽  
Albert L. Goldfinch
Keyword(s):  
Centrifugal Pump ◽  
Two Phase Flow ◽  
Flow Direction ◽  
Semiempirical Method ◽  
Head Loss ◽  
Phase Flow ◽  
Loss Ratio ◽  
Centrifugal Pumps ◽  
Reversed Flow ◽  
Two Phase

The semiempirical method described combines the ideal performance of a centrifugal pump with experimental data for single and two-phase flow to produce a so-called “head-loss ratio,” which is the apparent loss of head in two-phase flow divided by the loss of head in single-phase flow. This head-loss ratio is shown to be primarily a function of void fraction. It is demonstrated that the measured characteristics of a centrifugal pump operating in two-phase flow in normal rotation and normal and reversed flow directions (first and second -quadrant operation) and in reversed rotation and reversed flow direction (third-quadrant operation) can be reproduced with acceptable accuracy.

Two-phase flow regimes of condensing R-134a at low mass flux in rectangular microchannels

2017 ◽  
Vol 84 ◽  
pp. 92-103 ◽  
Author(s):  
Michael A. Vanderputten ◽  
Tabeel A. Jacob ◽  
Maria Sattar ◽  
Nouman Ali ◽  
Brian M. Fronk
Keyword(s):  
Mass Flux ◽  
Two Phase Flow ◽  
Flow Regimes ◽  
Phase Flow ◽  
Two Phase ◽  
Rectangular Microchannels ◽  
Low Mass ◽  
R 134A

scholarly journals Numerical Prediction of Two-Phase Flow in Tube Bundles with a CFD Porous Media Approach Based on Mixture Model and a Void Fraction Correlation

2021 ◽  
Vol 321 ◽  
pp. 01002
Author(s):  
Claire Dubot ◽  
Vincent Melot ◽  
Claudine Béghein ◽  
Cyrille Allery ◽  
Clément Bonneau
Keyword(s):  
Porous Media ◽  
Mixture Model ◽  
Void Fraction ◽  
Two Phase Flow ◽  
Numerical Prediction ◽  
Phase Flow ◽  
Two Phase ◽  
Mixture Density ◽  
Tube Bundles ◽  
Phase Mixture

Being able to predict the void fraction is essential for a numerical prediction of the thermohydraulic behaviour in steam generators. Indeed, it determines two-phase mixture density and affects two-phase mixture velocity which enable to evaluate the pressure drop of heat exchanger, the mass transfer and heat transfer coefficients. In this study, the flow is modelled by coupling Ansys Fluent with an in-house code library where a CFD porous media approach is implemented. In this code, the two-phase flow has been modelled so far using the Eulerian model. However, this two-phase model requires interaction laws between phases which are not known and/or reliable for a flow within a tube bundle. The aim of this paper is to use the mixture model, for which it is easier to implement suitable correlations for tube bundles. By expressing the relative velocity, as a function of slip, the void fraction model of Feenstra et al. developed for upward cross-flow through horizontal tube bundles is introduced. With this method, physical phenomena that occur in tube bundles are taken into consideration in the mixture model. The developed approach is validated based on the experimental results obtained by Dowlati et al.

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