An In-Situ Volume Fraction Sensor For Two-Phase Flows of Non-Electrolytes

1973 ◽  
Vol 12 (02) ◽  
Author(s):  
G.A. Gregory ◽  
L. Mattar
Keyword(s):  
Volume Fraction ◽  
Two Phase Flows ◽  
Two Phase

scholarly journals Simulation of the Effect of Oil Volume Fractions in an Oil-Water Flows Along a Circular Pipe: A Finite Element Approach

2018 ◽  
Vol 10 (5) ◽  
pp. 19
Author(s):  
Ferdusee Akter ◽  
Md. Bhuyan ◽  
Ujjwal Deb
Keyword(s):  
Finite Element ◽  
Volume Fraction ◽  
Fluid Velocity ◽  
Galerkin Approximation ◽  
Computational Domain ◽  
Two Phase Flows ◽  
Two Phase ◽  
Volume Fractions ◽  
Oil In Water ◽  
Element Approach

Two phase flows in pipelines are very common in industries for the oil transportations. The aim of our work is to observe the effect of oil volume fraction in the oil in water two phase flows. The study has been accomplished using a computational model which is based on a Finite Element Method (FEM) named Galerkin approximation. The velocity profiles and volume fractions are performed by numerical simulations and we have considered the COMSOL Multiphysics Software version 4.2a for our simulation. The computational domain is 8m in length and 0.05m in radius. The results show that the velocity of the mixture decreases as the oil volume fraction increases. It should be noted that if we gradually increase the volume fractions of oil, the fluid velocity also changes and the saturated level of the volume fraction is 22.3%.

Nucleation and Growth of Liquid Droplets Under a Shear Flow

1991 ◽  
Vol 248 ◽  
Author(s):  
F. Perrot ◽  
T. Baumberger
Keyword(s):  
Shear Flow ◽  
Volume Fraction ◽  
Liquid Droplets ◽  
Subsequent Growth ◽  
Two Phase ◽  
Angle Scattering ◽  
Steady Shear Flow ◽  
Mixture Volume ◽  
New Phase

AbstractPhase separation in an off-critical binary mixture is studied under an uniform and steady shear flow. The nucleation and subsequent growth of droplets in aweakly supersaturated mixture (volume fraction of the new phase smaller than 10%) is studied by small angle scattering and turbidity measurements. The completion of the nucleation process is shown to be accelerated by the shear flow. At very low supersaturation, a strong effect of shear is detected which can be related to shear-triggered nucleation. In situ measurements ’of the surface tension between the two phase-separating phases obtained by studying the deformation and tilt of the growing droplets is discussed.

scholarly journals Wake attenuation in large Reynolds number dispersed two-phase flows

2008 ◽  
Vol 366 (1873) ◽  
pp. 2177-2190 ◽  
Author(s):  
Frédéric Risso ◽  
Véronique Roig ◽  
Zouhir Amoura ◽  
Guillaume Riboux ◽  
Anne-Marie Billet
Keyword(s):  
Reynolds Number ◽  
Volume Fraction ◽  
Bubble Diameter ◽  
Temporal Variations ◽  
The Body ◽  
Experimental Investigations ◽  
Large Reynolds Number ◽  
Two Phase Flows ◽  
Two Phase ◽  
Multi Body

The dynamics of high Reynolds number-dispersed two-phase flow strongly depends on the wakes generated behind the moving bodies that constitute the dispersed phase. The length of these wakes is considerably reduced compared with those developing behind isolated bodies. In this paper, this wake attenuation is studied from several complementary experimental investigations with the aim of determining how it depends on the body Reynolds number and the volume fraction α . It is first shown that the wakes inside a homogeneous swarm of rising bubbles decay exponentially with a characteristic length that scales as the ratio of the bubble diameter d to the drag coefficient C d , and surprisingly does not depend on α for 10 −2 ≤ α ≤10 −1 . The attenuation of the wakes in a fixed array of spheres randomly distributed in space ( α =2×10 −2 ) is observed to be stronger than that of the wake of an isolated sphere in a turbulent incident flow, but similar to that of bubbles within a homogeneous swarm. It thus appears that the wakes in dispersed two-phase flows are controlled by multi-body interactions, which cause a much faster decay than turbulent fluctuations having the same energy and integral length scale. Decomposition of velocity fluctuations into a contribution related to temporal variations and that associated to the random character of the body positions is proposed as a perspective for studying the mechanisms responsible for multi-body interactions.

Recent developments in hydrodynamic stability of two-phase flows

2012 ◽  
Vol 9 (1) ◽  
pp. 125-130
Author(s):  
A.N. Osiptsov ◽  
S.A. Boronin
Keyword(s):  
Boundary Layer ◽  
Particle Concentration ◽  
Volume Fraction ◽  
Time Interval ◽  
Dusty Gas ◽  
Two Phase Flows ◽  
Two Phase ◽  
Layer Width ◽  
Dispersed Flows ◽  
Optimal Disturbances

In the framework of two-continuum model, the stability of plane-parallel dispersed flows is analyzed. Several flow configurations are considered and several new factors are analyzed. The factors include: particle velocity slip and particle concentration non-uniformity in the main flow, non-Stokesian components of the interphase force and finite volume fraction of the dispersed phase. It is found that the new factors modify significantly the parameters of the fastest growing mode and change the critical Reynolds number of two-phase flows. A method for studying algebraic (non-modal) instability and optimal disturbances to dispersed flows is proposed. While studying the non-modal instability of the dusty-gas boundary-layer flow with a non-uniform particle concentration, we found that the disturbances with the maximum energy gain at a limited time interval are streamwise-elongated structures (streaks). As compared to the flow of a particle-free fluid, optimal disturbances to the dusty-gas flow gain much larger kinetic energy even at the boundary layer width-averaged mass concentration of ten percent, which leads to significant amplification of non-modal instability mechanism due to the presence of suspended particles.

Measurement of a Void Fraction in Bubbly Gas-Water Two Phase Flows Using Differential Pressure Technique

2012 ◽  
Vol 152-154 ◽  
pp. 1221-1226
Author(s):  
H.A.M. Hasan Abbas
Keyword(s):  
Experimental Study ◽  
Void Fraction ◽  
Volume Fraction ◽  
Differential Pressure ◽  
Flow Density ◽  
Two Phase Flows ◽  
Two Phase ◽  
Gas Volume Fraction ◽  
Fraction Measurement ◽  
Gas Volume

Multiphase flows, where two or even three fluids flow simultaneously in a pipe are becoming increasingly important in industry. In order to measure the flow rate of gas-water two phase flows accurately, the void fraction (gas volume fraction) in two phase flows must be precisely measured. The differential pressure technique has proven attractive in the measurement of volume fraction. This paper presents the theoretical and experimental study of the void fraction measurement in bubbly gas water two phase flows using differential pressure technique (the flow density meter).

scholarly journals NUMERICAL MODELING OF TWO-PHASE FLOWS USING THE TWO-FLUID TWO-PRESSURE APPROACH

2004 ◽  
Vol 14 (05) ◽  
pp. 663-700 ◽  
Author(s):  
THIERRY GALLOUËT ◽  
JEAN-MARC HÉRARD ◽  
NICOLAS SEGUIN
Keyword(s):  
Volume Fraction ◽  
Local Equilibrium ◽  
Finite Volume Methods ◽  
Convective System ◽  
Two Phase Flows ◽  
Step Method ◽  
Discontinuous Solutions ◽  
Fractional Step Method ◽  
Two Phase ◽  
Two Fluid

The present paper is devoted to the computation of two-phase flows using the two-fluid approach. The overall model is hyperbolic and has no conservative form. No instantaneous local equilibrium between phases is assumed, which results in a two-velocity two-pressure model. Original closure laws for interfacial velocity and interfacial pressure are proposed. These closures allow to deal with discontinuous solutions such as shock waves and contact discontinuities without ambiguity with the definition of Rankine–Hugoniot jump relations. Each field of the convective system is investigated, providing maximum principle for the volume fraction and the positivity of densities and internal energies are ensured when focusing on the Riemann problem. Two-finite volume methods are presented, based on the Rusanov scheme and on an approximate Godunov scheme. Relaxation terms are taken into account using a fractional step method. Eventually, numerical tests illustrate the ability of both methods to compute two-phase flows.

Microstructures and Mechanical Behavior of Two-Phase Niobium Silicide-Niobium Alloys

1988 ◽  
Vol 133 ◽  
Author(s):  
M. G. Mendiratta ◽  
D. M. Dimiduk
Keyword(s):  
Mechanical Behavior ◽  
Phase Transformations ◽  
Room Temperature ◽  
Volume Fraction ◽  
Two Phase ◽  
Niobium Alloys ◽  
Intermetallic Matrix ◽  
Two Phases ◽  
The Individual

ABSTRACTIn the Nb-Si system, it is possible to produce in-situ composites consisting of a brittle Nb5Si3 intermetallic matrix and ductile Nb particles. The two phases are thermochemically stable up to ∼ 1500∼C and are amenable to wide microstructural variations including morphology, volume fraction, and the size of the individual microconstituents. This paper presents microstructures and phase transformations in these composites as a function of composition and heat treatments and bend properties from room-temperature to 1400°C.

scholarly journals Re-Reflection Effect On Shock Waves in Two-Phase Flows through a Tube of Variable Cross-Section

2018 ◽  
Vol 3 (12) ◽  
pp. 67-73
Author(s):  
Kanti Pandey
Keyword(s):  
Cross Section ◽  
Volume Fraction ◽  
Particle Volume Fraction ◽  
Variable Cross Section ◽  
Variable Cross ◽  
Reflection Effect ◽  
Two Phase Flows ◽  
Particle Volume ◽  
Two Phase ◽  
Cross Sectional

In present paper Re-reflection  effect on  shock –waves in two-phase flows through a tube of variable cross-section is considered when particle  volume fraction appeared as an additional variable .It is concluded that re-reflected effects reduce the cross sectional  area .For two-phase flows when equilibrium is eventually established , presence of particle volume fraction , further reduce  the cross – sectional area. One dimensional area relation for a non – uniform , steady flow ahead of a shock   is obtained and concluded that  all the results are valid for the case   when  direction of the shock motion and the gas flow ahead of the  shock is same  .  In preparation of graphs Mathematica 7 is used .

Numerical Study of Two-Phase Flow in a Horizontal Pipeline Using an Unconditionally Hyperbolic Two-Fluid Model

2018 ◽  
Author(s):  
Raphael V. N. de Freitas ◽  
Carina N. Sondermann ◽  
Rodrigo A. C. Patricio ◽  
Aline B. Figueiredo ◽  
Gustavo C. R. Bodstein ◽  
...  
Keyword(s):  
Volume Fraction ◽  
Numerical Study ◽  
Fluid Model ◽  
Momentum Conservation ◽  
Design Stage ◽  
Two Phase Flows ◽  
Two Phase ◽  
Efficient Manner ◽  
Two Fluid Model ◽  
Two Fluid

Numerical simulation is a very useful tool for the prediction of physical quantities in two-phase flows. One important application is the study of oil-gas flows in pipelines, which is necessary for the proper selection of the equipment connected to the line during the pipeline design stage and also during the pipeline operation stage. The understanding of the phenomena present in this type of flow is more crucial under the occurrence of undesired effects in the duct, such as hydrate formation, fluid leakage, PIG passage, and valve shutdown. An efficient manner to model two-phase flows in long pipelines regarding a compromise between numerical accuracy and cost is the use of a one-dimensional two-fluid model, discretized with an appropriate numerical method. A two-fluid model consists of a system of non-linear partial differential equations that represent the mass, momentum and energy conservation principles, written for each phase. Depending on the two-fluid model employed, the system of equations may lose hyperbolicity and render the initial-boundary-value problem illposed. This paper uses an unconditionally hyperbolic two-fluid model for solving two-phase flows in pipelines in order to guarantee that the solution presents physical consistency. The mathematical model here referred to as the 5E2P (five equations and two pressures) comprises two equations of continuity and two momentum conservation equations, one for each phase, and one equation for the transport of the volume fraction. A priori this model considers two distinct pressures, one for each phase, and correlates them through a pressure relaxation procedure. This paper presents simulation cases for stratified two-phase flows in horizontal pipelines solved with the 5E2P coupled with the flux corrected transport method. The objective is to evaluate the numerical model capacity to adequately describe the velocities, pressures and volume fraction distributions along the duct.

A Numerical Investigation of Internal and External Two-Phase Flows of a Rotating Disk Atomizer

2012 ◽  
Author(s):  
Cheng-Xian (Charlie) Lin ◽  
Long Phan
Keyword(s):  
Volume Fraction ◽  
Numerical Study ◽  
Rotating Disk ◽  
Multiphase Model ◽  
Two Phase Flows ◽  
Two Phase ◽  
Liquid Distribution ◽  
Liquid Feed ◽  
Flow Rate Range ◽  
Uniform Liquid

In this paper, a numerical study has been carried out to model and simulate the air-water two-phase flows in and around a rotating disk atomizer, which uses multiple nozzles to breakout the water and forms droplets. The physical problem was simulated with an Eulerian multiphase model. The realizable two-equation turbulence model was used for the turbulent flow. The governing equations were solved with a finite volume based numerical method. The rotary frame approach was used to deal with the spinning disk. Numerical simulation was conducted in a disk rotational speed range of 1000 to 10000 rpm, a liquid feed flow rate range of 100 to 150 gpm. Both uniform and non-uniform liquid distribution conditions were considered. Detailed results about flow velocity and volume fraction fields inside and outside of the atomizer are presented and discussed. It was found that when liquid is nonuniformly distributed through the distributors, some of the nozzles could reach flooding conditions at lower rotational disk speed and liquid feed volume flow rates, as compared to uniform distribution cases.

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