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

Author(s):  
C. Béguin ◽  
T. Plagnard ◽  
S. Étienne

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.

Author(s):  
C. Béguin ◽  
É. Pelletier ◽  
S. Étienne

This paper proposes a relation for the added mass coefficient of spherical bubbles depending on void fraction based on results obtained by a semi-analytical method. This information is essential to completely characterize finely dispersed bubbly flows, where small spherical gas bubbles are present in a continuous liquid phase. Most of the closure relations for Euler-Euler or Euler-Lagrange models are obtained from experiments involving single bubbles. Their applicability to systems with high void fraction is therefore questionable. This paper uses solid harmonics to solve 3D potential flow around bubbles. Several configurations were calculated for different numbers of particles and spatial arrangements. Our results are compared with previous studies. Depending on the model proposed by previous authors, added mass forces could increase or decrease with the void fraction. This paper solves these discrepancies. The main purpose of this work is to develop simple formulas fitting our semi-analytical results. These simple formulas are suitable for further use, particularly as added mass models for multiphase flow averaged equations.


1982 ◽  
Vol 104 (3) ◽  
pp. 139-146 ◽  
Author(s):  
D. S. Weaver ◽  
D. Koroyannakis

A water tunnel study was conducted on a parallel triangular array of tubes with a pitch ratio of 1.375. The array was geometrically identical to that used previously in a wind tunnel study so that the tube response to cross flow could be compared. It was seen that the response curves for tube arrays in water are much less regular than those in air, creating ambiguity in defining the stability threshold. The irregularities are seen to be associated with shifts in relative tube mode and frequency. Arrays in water apparently first become unstable in one of the lowest frequencies of the band of frequencies associated with a given structural mode. The added mass coefficient computed from the observed frequency at instability is a little larger than the largest added mass coefficient obtained from existing theory for tube arrays in quiescent fluid.


Author(s):  
M Parmar ◽  
A Haselbacher ◽  
S Balachandar

The unsteady inviscid force on cylinders and spheres in subcritical compressible flow is investigated. In the limit of incompressible flow, the unsteady inviscid force on a cylinder or sphere is the so-called added-mass force that is proportional to the product of the mass displaced by the body and the instantaneous acceleration. In compressible flow, the finite acoustic propagation speed means that the unsteady inviscid force arising from an instantaneously applied constant acceleration develops gradually and reaches steady values only for non-dimensional times c ∞ t / R ≳10, where c ∞ is the freestream speed of sound and R is the radius of the cylinder or sphere. In this limit, an effective added-mass coefficient may be defined. The main conclusion of our study is that the freestream Mach number has a pronounced effect on both the peak value of the unsteady force and the effective added-mass coefficient. At a freestream Mach number of 0.5, the effective added-mass coefficient is about twice as large as the incompressible value for the sphere. Coupled with an impulsive acceleration, the unsteady inviscid force in compressible flow can be more than four times larger than that predicted from incompressible theory. Furthermore, the effect of the ratio of specific heats on the unsteady force becomes more pronounced as the Mach number increases.


Author(s):  
Sarra Zoghlami ◽  
Cédric Béguin ◽  
Stéphane Étienne

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.


2019 ◽  
Vol 342 ◽  
pp. 249-256
Author(s):  
Xie Teng ◽  
Liu Jianhu ◽  
Wang Haikun ◽  
Li Haitao ◽  
Pei Du ◽  
...  

2002 ◽  
Vol 16 (2) ◽  
pp. 123-136 ◽  
Author(s):  
T. NAKAMURA ◽  
K. HIROTA ◽  
Y. WATANABE ◽  
N.W. MUREITHI ◽  
T. KUSAKABE ◽  
...  

Author(s):  
Andre´ L. C. Fujarra ◽  
Celso P. Pesce

Vortex Induced Vibrations (VIV) of elastically mounted rigid cylinders, with low mass-damping parameter values, are strongly dependent on the added mass coefficient. This paper aims to contribute to the technical literature by presenting some results from experiments carried out at University of Sa˜o Paulo – USP and at the Sa˜o Paulo State Technological Research Institute – IPT. A cantilevered rigid cylinder was mounted on an elastic (leaf spring) two-degree-of-freedom device. The device is not only an elastic support, but acts also as a special mechanical transducer to measure accelerations/forces/displacements in the stream-wise (x) and the cross-wise (y) directions. A comprehensive experimental calibration of such a device was carried out, both “in air” and “in water”. The added mass coefficient in the cross-wise direction was indirectly determined from forces and acceleration measurements as a function of the reduced velocity. Results from time-domain and frequency-domain analyses are compared with those obtained by Vikestad et al. (2000) [1].


2011 ◽  
Vol 18 (1) ◽  
pp. 17-26 ◽  
Author(s):  
Hassan Ghassemi ◽  
Ehsan Yari

The Added Mass Coefficient computation of sphere, ellipsoid and marine propellers using Boundary Element Method Added mass is an important and effective dynamic coefficient in accelerating, non uniform motion as a result of fluid accelerating around a body. It plays an important role, especially in vessel roll motion, control parameters as well as in analyzing the local and global vibration of a vessel and its parts like propellers and rudders. In this article, calculating the Added Mass Coefficient has been examined for a sphere, ellipsoid, marine propeller and hydrofoil; using numerical Boundary Element Method. Since an Ellipsoid and a sphere have simple geometric shapes and the Analytical values of their added mass coefficients are available, so that the results of added mass matrix are obtained and evaluated, using the boundary element method. Then the added mass matrix is computed in a given geometrical and flow specifications for a specific propeller and its results are studied versus experimental results, which it's current numerical data In comparison with other numerical methods has a good conformity with experimental results. The most important advantage of the method in determining the added mass matrix coefficients for the surface and underwater vessels and the marine propellers is extracting all the added mass coefficients with very good Accuracy, while in other numerical methods it is impossible to extract all the coefficients with the Desired Accuracy.


1976 ◽  
Vol 76 (4) ◽  
pp. 653-674 ◽  
Author(s):  
C. Samuel Martin ◽  
M. Padmanabhan ◽  
C. D. Ponce-Campos

The rolling motion of a sphere on a smooth plane boundary in a simple-harmonic water motion has been analytically and experimentally investigated. For spheres having specific gravities ranging from 0·09 to 15·18 the sphere motion was found to be sinusoidal for both low and high values of the period parameter defined by Keulegan & Carpenter. The knowledge of the sphere motion, and hence the resultant force, allowed the determination of inertia and drag coefficients from Fourier-averaging techniques. Experiments in the inertial range yielded an added-mass coefficient of 1·2, compared with 0·67 from inviscid theory for translating spheres. For values of the period parameter greater than 30 the drag coefficient is reported to be approximately 0·74.


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