DYNAMICS OF AN IN-LINE TUBE ARRAY SUBJECTED TO STEAM–WATER CROSS-FLOW. PART I: TWO-PHASE DAMPING AND ADDED MASS

2002 ◽  
Vol 16 (2) ◽  
pp. 123-136 ◽  
Author(s):  
T. NAKAMURA ◽  
K. HIROTA ◽  
Y. WATANABE ◽  
N.W. MUREITHI ◽  
T. KUSAKABE ◽  
...  
Keyword(s):  
Cross Flow ◽  
Added Mass ◽  
Two Phase ◽  
Phase Damping ◽  
Flow Part

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.

Wall Proximity and Curvature Effect on Added Mass Forces in Two-Phase Cross-Flow

2014 ◽  
Author(s):  
C. Béguin ◽  
T. Plagnard ◽  
S. Étienne
Keyword(s):  
Cross Flow ◽  
Added Mass ◽  
Two Phase ◽  
Averaged Equations ◽  
Flow Potential ◽  
Mass Coefficient ◽  
Added Mass Coefficient ◽  
A New Technique ◽  
Infinite Wall ◽  
Wall Proximity

This paper studies the effect of wall proximity and wall curvature on the added mass coefficient of a spherical bubble. Results are based on a semi-analytical method. This information is essential to completely characterize finely dispersed bubbly flows in two-phase cross flow. In such flows small spherical gas bubbles are present in a continuous liquid phase close to a cylinder. This paper uses solid harmonics to solve 3D potential flow around a bubble and a wall. A new technique is developed to calculate the flow potential around a sphere and a cylinder using solid harmonics. Several configurations were calculated: one bubble close to an infinite wall, one bubble close to a cylinder and one bubble close to a spherical wall. Our results are compared with previous studies. As expected added mass forces increase in the vicinity of the wall and for lower curvature. The main purpose of this work is to understand the effect of wall curvature and proximity on added mass. These results are suitable for further use, particularly as added mass models for multiphase flow averaged equations.

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.

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.

Fluid-Structure Interactions in a Tube Bundle Subject to Cross-Flow. Part B : Two-Phase Flow Modeling

2014 ◽  
Author(s):  
Eliott R. Tixier ◽  
Cédric R. Béguin ◽  
Stephane Etienne ◽  
Dominique Pelletier ◽  
Alexander Hay ◽  
...  
Keyword(s):  
Two Phase Flow ◽  
Tube Bundle ◽  
Cross Flow ◽  
Phase Flow ◽  
Flow Modeling ◽  
Fluid Structure Interactions ◽  
Two Phase ◽  
Fluid Structure ◽  
Flow Part

Studies on two-phase cross flow. Part III: Characteristics of unsteady flow behavior

1986 ◽  
Vol 12 (2) ◽  
pp. 185-202 ◽  
Author(s):  
M. Yokosawa ◽  
Y. Kozawa ◽  
A. Inoue ◽  
S. Aoki
Keyword(s):  
Unsteady Flow ◽  
Flow Behavior ◽  
Cross Flow ◽  
Two Phase ◽  
Flow Part
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