scholarly journals Correlation Between Vibration Excitation Forces and the Dynamic Characteristics of Two-Phase Flow in a Rotated Triangular Tube Bundle

2006 ◽  
Author(s):  
C. Zhang ◽  
M. J. Pettigrew ◽  
N. W. Mureithi
Keyword(s):  
Void Fraction ◽  
Cross Flow ◽  
Main Flow ◽  
Phase Flow ◽  
Two Phase ◽  
Drag Forces ◽  
Vibration Excitation ◽  
Tube Bundles ◽  
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 flow and 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. The distributions of both void fraction and bubble velocity in rotated-triangular tube bundles were obtained. Somewhat unexpected but significant quasi-periodic forces in both the drag and lift directions were measured. The present work aims at understanding the nature of such unexpected drag and lift quasi-periodic forces. An experimental program was undertaken with a rotated-triangular array of cylinders subjected to air/water flow to simulate two-phase mixtures. Fiber-optic probes were developed to measure local void fraction. Both the dynamic lift and drag forces were measured with a strain gage instrumented cylinder. The investigation showed that the quasi-periodic drag and lift forces are generated by different mechanisms that have not been observed so far. The quasi-periodic drag forces appear related to the momentum flux fluctuations in the main flow path between the cylinders. The quasi-periodic lift forces, on the other hand, are mostly correlated to oscillations in the wake of the cylinders. The relationships between the lift or drag forces and the dynamic characteristics of two-phase flow are established through fluid mechanics momentum equations. The quasi-periodic lift forces are related to local void fraction measurements in the unsteady wake area between upstream and downstream cylinders. The quasi-periodic drag forces correlate well with similar measurements in the main flow stream between cylinders.

Correlation Between Vibration Excitation Forces and the Dynamic Characteristics of Two-Phase Cross Flow in a Rotated-Triangular Tube Bundle

2008 ◽  
Vol 130 (1) ◽  
Author(s):  
C. Zhang ◽  
M. J. Pettigrew ◽  
N. W. Mureithi
Keyword(s):  
Void Fraction ◽  
Cross Flow ◽  
Main Flow ◽  
Experimental Program ◽  
Two Phase ◽  
Drag Forces ◽  
Vibration Excitation ◽  
Tube Bundles ◽  
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 flow and 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. The distributions of both void fraction and bubble velocity in rotated-triangular tube bundles were obtained. Somewhat unexpected but significant quasiperiodic forces in both the drag and lift directions were measured. The present work aims at understanding the nature of such unexpected drag and lift quasiperiodic forces. An experimental program was undertaken with a rotated-triangular array of cylinders subjected to air/water flow to simulate two-phase mixtures. Fiber-optic probes were developed to measure local void fraction. Both the dynamic lift and drag forces were measured with a strain gage instrumented cylinder. The investigation showed that the quasiperiodic drag and lift forces are generated by different mechanisms that have not been previously observed. The quasiperiodic drag forces appear related to the momentum flux fluctuations in the main flow path between the cylinders. The quasiperiodic lift forces, on the other hand, are mostly correlated to oscillations in the wake of the cylinders. The quasiperiodic lift forces are related to local void fraction measurements in the unsteady wake area between upstream and downstream cylinders. The quasiperiodic drag forces correlate well with similar measurements in the main flow stream between cylinders.

Development of Models Correlating Vibration Excitation Forces to Dynamic Characteristics of Two-Phase Flow in a Tube Bundle

2007 ◽  
Author(s):  
C. Zhang ◽  
M. J. Pettigrew ◽  
N. W. Mureithi
Keyword(s):  
Dynamic Characteristics ◽  
Two Phase Flow ◽  
Tube Bundle ◽  
Flow Path ◽  
Main Flow ◽  
Phase Flow ◽  
Two Phase ◽  
Drag Forces ◽  
Vibration Excitation ◽  
Lift Forces

Recent experiments reveal that somewhat unexpected but significant quasi-periodic forces in both the drag and lift directions existed in a rotated triangular tube bundle subjected to two-phase cross flow. The quasi-periodic drag forces appear to be related to the momentum flux fluctuations in the main flow path between the cylinders. The quasi-periodic lift forces, on the other hand, are mostly correlated to the oscillation in the wake of the cylinders. The objective of this work is to develop semi-analytical models for correlating vibration excitation forces to dynamic characteristics of two-phase flow in a rotated triangular tube bundle and understanding the nature of vibration excitation forces. The relationships between the lift or drag forces and the dynamic characteristics of two-phase flow are established through fluid mechanics momentum equations. A model has been developed to correlate the void fraction fluctuation in the main flow path and the dynamic drag forces. A second model has been developed for correlating the oscillation in the wake of the cylinders and the dynamic lift forces. Although still preliminary, each model can predict the corresponding forces relatively well.

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.

scholarly journals Numerical Prediction of Two-Phase Flow through a Tube Bundle Based on Reduced-Order Model and a Void Fraction Correlation

Entropy ◽  
2021 ◽  
Vol 23 (10) ◽  
pp. 1355
Author(s):  
Claire Dubot ◽  
Cyrille Allery ◽  
Vincent Melot ◽  
Claudine Béghein ◽  
Mourad Oulghelou ◽  
...  
Keyword(s):  
Void Fraction ◽  
Grassmann Manifold ◽  
Tube Bundle ◽  
Cross Flow ◽  
Horizontal Tube ◽  
Phase Flow ◽  
Two Phase ◽  
Tube Bundles ◽  
Flow Through ◽  
Phase Mixture

Predicting the void fraction of a two-phase flow outside of tubes is essential to evaluate the thermohydraulic behaviour in steam generators. Indeed, it determines two-phase mixture properties and affects two-phase mixture velocity, which enable evaluating the pressure drop of the system. The two-fluid model for the numerical simulation of two-phase flows requires interaction laws between phases which are not known and/or reliable for a flow within a tube bundle. Therefore, the mixture model, for which it is easier to implement suitable correlations for tube bundles, is used. Indeed, by expressing the relative velocity as a function of slip, the void fraction model of Feenstra et al.and Hibiki et al. developed for upward cross-flow through horizontal tube bundles is introduced and compared. With the method suggested in this paper, the physical phenomena that occur in tube bundles are taken into consideration. Moreover, the tube bundle is modelled using a porous media approach where the Darcy–Forchheimer term is usually defined by correlations found in the literature. However, for some tube bundle geometries, these correlations are not available. The second goal of the paper is to quickly compute, in quasi-real-time, this term by a non-intrusive parametric reduced model based on Proper Orthogonal Decomposition. This method, named Bi-CITSGM (Bi-Calibrated Interpolation on the Tangent Subspace of the Grassmann Manifold), consists in interpolating the spatial and temporal bases by ITSGM (Interpolation on the Tangent Subspace of the Grassmann Manifold) in order to define the solution for a new parameter. The two developed methods are validated based on the experimental results obtained by Dowlati et al. for a two-phase cross-flow through a horizontal tube bundle.

Vibration Excitation Forces in a Normal Triangular Tube Bundle Subjected to Two-Phase Cross Flow

2011 ◽  
Author(s):  
E. S. Perrot ◽  
N. W. Mureithi ◽  
M. J. Pettigrew ◽  
G. Ricciardi
Keyword(s):  
Tube Bundle ◽  
Cross Flow ◽  
Random Excitation ◽  
Two Phase ◽  
Constant Frequency ◽  
Fluid Forces ◽  
Drag Forces ◽  
Wide Range ◽  
Drag And Lift ◽  
Lift And Drag

This paper presents test results of vibration forces in a normal triangular tube bundle subjected to air-water cross-flow. The dynamic lift and drag forces were measured with strain gage instrumented cylinders. The array has a pitch-to-diameter ratio of 1.5, and the tube diameter is 38 mm. A wide range of void fraction and fluid velocities were tested. The experiments revealed significant forces in both the drag and lift directions. Constant frequency and quasi-periodic fluid forces were found in addition to random excitation. These forces were analyzed and characterized to understand their origins. The forces were found to be dependent on the position of the cylinder within the bundle. The results are compared with those obtained with flexible cylinders in the same tube bundle and to those for a rotated triangular tube bundle. These comparisons reveal the influence of quasi-periodic forces on tube motions.

scholarly journals A Ghost-Cell Immersed Boundary Method for Wave–Structure Interaction Using a Two-Phase Flow Model

Water ◽  
2020 ◽  
Vol 12 (12) ◽  
pp. 3346
Author(s):  
Yuan-Shiang Tsai ◽  
Der-Chang Lo
Keyword(s):  
Immersed Boundary Method ◽  
Flow Model ◽  
Two Phase Flow ◽  
Immersed Boundary ◽  
Phase Flow ◽  
Ghost Cell ◽  
Two Phase ◽  
Boundary Method ◽  
Lift Forces ◽  
Drag And Lift

The air-water two-phase flow model is developed to study the transformation of monochromatic waves passing over the submerged structure. The level set method is employed to describe the motion of the interface while the effect of the immersed object on the fluid is resolved using the ghost-cell immersed boundary method. The computational domain integrated with the air-water and fluid-solid phases allows the use of uniform Cartesian grids. The model simulates the wave generation, wave decomposition over a submerged trapezoidal breakwater, and the formation of the vortices as well as the drag and lift forces caused by the surface waves over three different configurations of the submerged structures. The numerical results show the capability of the present model to accurately track the deformation of the free surface. In addition, the variation of the drag and lift forces depend on the wavelength and wave induced vortices around the submerged object. Hence, the study observes that the triangular structure experiences the relatively small wave force.

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.

scholarly journals DYNAMICS OF TWO-PHASE FLOW ACROSS HORIZONTAL TUBE BUNDLES - A REVIEW

2005 ◽  
Vol 4 (2) ◽  
Author(s):  
G. Ribatskia ◽  
J. R. Thome
Keyword(s):  
Void Fraction ◽  
Two Phase Flow ◽  
Experimental Studies ◽  
Horizontal Tube ◽  
Prediction Methods ◽  
Phase Flow ◽  
Two Phase ◽  
Pressure Drops ◽  
Frictional Pressure Drop ◽  
Tube Bundles

This paper presents a state-of-the-art review of the hydrodynamic aspects of two-phase flow across horizontal tube bundles. The review covers studies related to the evaluation of void fraction, two-phase flow behaviors and pressure drops on the shell side of staggered and in-line tube bundles for upward, downward and side-to-side flows. This study of the literature critically describes the proposed flow pattern maps and semi-empirical correlations for predicting void fraction and frictional pressure drop. These predicting methods are generally based on experimental results for adiabatic air-water flows. A limited number of experimental studies with R-11 and R-113 were also carried out in the past. The review shows noticeable discrepancies among the available prediction methods. Finally, this study suggests that further research focusing on the development of representative databanks and new prediction methods is still necessary.

Effect of Void Fraction on Vibrational Behavior of Tubes in Tube Bundle Under Two-Phase Cross Flow

1997 ◽  
Vol 119 (3) ◽  
pp. 457-463 ◽  
Author(s):  
H. Y. Lian ◽  
G. Noghrehkar ◽  
A. M. C. Chan ◽  
M. Kawaji
Keyword(s):  
Void Fraction ◽  
Two Phase Flow ◽  
Tube Bundle ◽  
Dynamic Pressure ◽  
Damping Ratio ◽  
Cross Flow ◽  
Vibration Measurement ◽  
Phase Flow ◽  
Two Phase ◽  
Vibrational Behavior

The effects of local two-phase flow parameters on the vibrational behavior of tubes have been studied in an in-line 5 × 20 tube bundle subjected to air-water cross-flow. One of the tubes was flexibly mounted and instrumented for vibration measurement and the others were rigid. Parameters obtained include local void fraction fluctuations, RMS amplitude of void fraction fluctuations, void fraction distributions across the tube bundle, flow regimes based on probability density function of void fraction signals, damping ratio, and tube vibration response as a function of mass flux, void fraction and dynamic pressure. Damping and tube vibration amplitude in two-phase flow have been found to be closely related to the RMS amplitudes of the local void fraction fluctuations and dynamic pressure fluctuations, respectively.

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.

Sign in / Sign up

Export Citation Format

Share Document