scholarly journals Analysis of Conductance Probes for Two-Phase Flow and Holdup Applications

Sensors ◽  
2020 ◽  
Vol 20 (24) ◽  
pp. 7042
Author(s):  
José-Luis Muñoz-Cobo ◽  
Yago Rivera ◽  
Cesar Berna ◽  
Alberto Escrivá
Keyword(s):  
Boundary Conditions ◽  
Two Phase Flow ◽  
Effective Medium Theory ◽  
Potential Difference ◽  
Phase Flow ◽  
Two Phase ◽  
Medium Theory ◽  
Average Potential ◽  
Measured System ◽  
Comparison Of The Results

In this paper we perform an analysis of the conductance probes used in two-phase flow applications especially for two-phase flow tomography of annular flow, to measure the waves produced in the interface with different boundary conditions without perturbing the flow, and in addition we examine the holdup applications as measuring the average void fraction in a given region. The method used to obtain the detector conductance between the electrodes is to solve analytically the generalized Laplace equation in 3D with the boundary conditions of the problem, and then to obtain the average potential difference between the detector electrodes. Then, dividing the current intensity circulating between the emitter and the receiver electrodes by the average potential difference yields the probe conductance, which depends on the geometric and physical characteristics of the measured system and the probe. This conductance is then non-dimensionalized by dividing by the conductance of the pipe full of water. In this way a set of analytical expression have been obtained for the conductance of two-plate sensors with different geometries and locations. We have performed an exhaustive comparison of the results obtained using the equations deduced in this paper with the experimental data from several authors in different cases with very good agreement. In some cases when the distribution of bubbles is not homogeneous, we have explored the different alternatives of the effective medium theory (EMT) in terms of the self-consistent EMT and the non-consistent EMT.

A Validated Two-Phase Flow Large Eddy Simulation Methodology

2013 ◽  
Author(s):  
Feng Xiao ◽  
Mehriar Dianat ◽  
James J. McGuirk
Keyword(s):  
Boundary Conditions ◽  
Level Set ◽  
Two Phase Flow ◽  
Local Level ◽  
Density Ratio ◽  
Cross Flow ◽  
Liquid Jet ◽  
Phase Flow ◽  
Two Phase ◽  
Primary Breakup

A robust two-phase flow LES methodology is described, validated and applied to simulate primary breakup of a liquid jet injected into an airstream in either co-flow or cross-flow configuration. A Coupled Level Set and Volume of Fluid method is implemented for accurate capture of interface dynamics. Based on the local Level Set value, fluid density and viscosity fields are treated discontinuously across the interface. In order to cope with high density ratio, an extrapolated liquid velocity field is created and used for discretisation in the vicinity of the interface. Simulations of liquid jets discharged into higher speed airstreams with non-turbulent boundary conditions reveals the presence of regular surface waves. In practical configurations, both air and liquid flows are, however, likely to be turbulent. To account for inflowing turbulent eddies on the liquid jet interface primary breakup requires a methodology for creating physically correlated unsteady LES boundary conditions, which match experimental data as far as possible. The Rescaling/Recycling Method is implemented here to generate realistic turbulent inflows. It is found that liquid rather than gaseous eddies determine the initial interface shape, and the downstream turbulent liquid jet disintegrates much more chaotically than the non-turbulent one. When appropriate turbulent inflows are specified, the liquid jet behaviour in both co-flow and cross-flow configurations is correctly predicted by the current LES methodology, demonstrating its robustness and accuracy in dealing with high liquid/gas density ratio two-phase systems.

New Experimental Data and Analysis for Two-Phase Flow-Induced Vibration of Tube Bundles: Preliminary Results

2003 ◽  
Author(s):  
Deepanjan Mitra ◽  
Vijay K. Dhir ◽  
Ivan Catton
Keyword(s):  
Two Phase Flow ◽  
Structural Parameters ◽  
Cross Flow ◽  
Instability Criterion ◽  
Phase Flow ◽  
Flow Induced Vibration ◽  
Two Phase ◽  
Void Fractions ◽  
Comparison Of The Results ◽  
Square Array

In the past, fluid-elastic instability in two-phase flow has been largely investigated with air-water flow. In this work, new experiments are conducted in air-water cross-flow with a fully flexible 5 × 3 normal square array having pitch-to-diameter ratio of 1.4. The tubes have a diameter of 0.016 m and a length of 0.21 m. The vibrations are measured using strain gages installed on piano wires used to suspend the tubes. Experiments are carried out for void fractions from 0%–30%. A comparison of the results of the current tests with previous experiments conducted in air-water cross-flow shows that instability occurs earlier in a fully flexible array as compared to a flexible tube surrounded by rigid tubes in an array. An attempt is made to separate out the effects of structural parameters of three different experimental datasets by replotting the instability criterion by incorporating the instability constant K, in the reduced velocity parameter.

Two-phase flow simulation of mist film cooling with deposition for various boundary conditions

2017 ◽  
Vol 71 (9) ◽  
pp. 895-909 ◽  
Author(s):  
Jin Wang ◽  
QianQian Li ◽  
Bengt Sundén ◽  
Jakov Baleta ◽  
Milan Vujanović
Keyword(s):  
Boundary Conditions ◽  
Film Cooling ◽  
Two Phase Flow ◽  
Flow Simulation ◽  
Phase Flow ◽  
Two Phase ◽  
Various Boundary Conditions

Numerical Simulation of Two-Phase Flow in Injection Nozzles: Interaction of Cavitation and External Jet Formation

2003 ◽  
Vol 125 (6) ◽  
pp. 963-969 ◽  
Author(s):  
Weixing Yuan ◽  
Gu¨nter H. Schnerr
Keyword(s):  
Numerical Simulation ◽  
Boundary Conditions ◽  
Strong Interaction ◽  
Two Phase Flow ◽  
Nozzle Flow ◽  
Phase Flow ◽  
Jet Formation ◽  
Two Phase ◽  
Internal Problem

The present investigation demonstrates the strong interaction of cavitating nozzle flow with the outside jet formation. Due to the strong sensitivity of cavitation on the imposed boundary conditions, simulations with restriction on the internal problem are qualitatively and quantitatively incorrect, so that phenomena like hydraulic flip and supercavitation cannot be revealed. Our results indicate the potential of cavitation for enhancement of atomization and spray quality.

The Numerical Simulation on Steam-Water Two-Phase Flow Field of Car Exhaust Pipe

2012 ◽  
Vol 490-495 ◽  
pp. 3786-3791
Author(s):  
Qing Guo Liu ◽  
Yan Ma
Keyword(s):  
Flow Field ◽  
Boundary Conditions ◽  
Two Phase Flow ◽  
Exhaust Pipe ◽  
Phase Flow ◽  
Two Phase ◽  
Split Ratio ◽  
Car Exhaust ◽  
Wall Boundary Conditions ◽  
Distribution Rule

The flow field of car exhaust pipe using ethanol gasoline has been researched, the continuity equation of a mixed two-phase model have been established by means of the mathematical model of two-phase flow field, and the simulation for the velocity distribution of droplets radial slipping in exhaust gas have been achieved. By using the divided grid and setting these four boundary conditions as conditions of the entrance, flow conditions at the end of the export, overflow conditions of the export, solid-wall boundary conditions, the iterative steps of calculation process and the relationship among the residuals of various parameters have been obtained. State of exhaust flow have been calculated using algebraic slip model (ASM) ,obtaining the distribution rule of the internal flow field in exhaust pipe for the disconnection of steam-water ,and the characteristics relationship of separation for two-phase flow field of steam-water. The characteristic relationship among flow, split ratio and separation efficiency have been numerically simulated. The existence of the best range of split ratio for a particular exhaust pipe has been confirmed.

Magma dynamics using FD-PDE: a new, PETSc-based, finite-difference staggered-grid framework for solving partial differential equations

2020 ◽  
Author(s):  
Adina E. Pusok ◽  
Dave A. May ◽  
Richard F. Katz
Keyword(s):  
Free Surface ◽  
Partial Differential Equations ◽  
Finite Difference ◽  
Boundary Conditions ◽  
Differential Operators ◽  
Two Phase Flow ◽  
Flow Dynamics ◽  
Staggered Grid ◽  
Phase Flow ◽  
Two Phase

<p>All divergent plate boundaries are associated with magmatism, yet its role in their dynamics and deformation is not known. The RIFT-O-MAT project seeks to understand how magmatism promotes and shapes rifts in continental and oceanic lithosphere by using models that build upon the two-phase flow theory of magma/rock interaction. Numerical models of magma segregation from partially molten rocks are usually based on a system of equations for conservation of mass, momentum and energy. One key challenge of these problems is to compute a mass-conservative flow field that is suitable for advecting thermochemically active material that feeds back on the flow. This feedback tends to destabilise the coupled mechanics+thermochemical solver. </p><p>Staggered grid finite-volume/difference methods are: mimetic (i.e., discrete differential operators mimic the properties of the continuous differential operators); conservative by construction; inf-sup stable and "light weight" (small stencil) thus they are well suited to address these problems. We present a new framework for finite difference staggered grids for solving partial differential equations (FD-PDE) that allows testable and extensible code for single-/two-phase flow magma dynamics. We build the framework using PETSc (Balay et al., 2019) and make use of the new features for staggered grids, such as DMStag. The aim is to separate the user input from the discretization of governing equations, allow for extensible development, and implement a robust framework for testing. Any customized applications can be created easily, without interfering with previous work or tests.</p><p>Here, we present benchmark and performance results with our new FD-PDE framework. In particular, we focus on preliminary results of a two-phase flow mid-ocean ridge (MOR) model with a free surface and extensional boundary conditions. We compare flow calculations with previous work on MORs that either employed two-phase flow dynamics with kinematic boundary conditions (i.e., corner flow, Spiegelman and McKenzie, 1987), or single-phase flow dynamics with free surface (i.e., Behn and Ito, 2008). In the latter case, the effect of magma is parameterised according to a priori expectations of its role. </p><p> </p><p>Balay et al. (2019), PETSc Users Manual, ANL-95/11 - Revision 3.12, 2019.</p><p>Spiegelman and McKenzie (1987), EPSL, 83 (1-4), 137-152.</p><p>Behn and Ito (2008), Geochem. Geophys. Geosyst., 9, Q08O10.</p>

New Method to Determine the Velocities of Particles on a Solid Propellant Surface in a Solid Rocket Motor

2005 ◽  
Vol 127 (9) ◽  
pp. 1057-1061 ◽  
Author(s):  
Yumin Xiao ◽  
R. S. Amano ◽  
Timin Cai ◽  
Jiang Li
Keyword(s):  
Boundary Conditions ◽  
Combustion Chamber ◽  
Solid Propellant ◽  
Two Phase Flow ◽  
New Method ◽  
Phase Flow ◽  
Solid Rocket Motor ◽  
Two Phase ◽  
Solid Rocket ◽  
Propellant Surface

Use of aluminized composite solid propellants and submerged nozzles are common in solid rocket motors (SRM). Due to the generation of slag, which injects into a combusted gas flow, a two-phase flow pattern is one of the main flow characteristics that need to be investigated in SRM. Validation of two-phase flow modeling in a solid rocket motor combustion chamber is the focus of this research. The particles’ boundary conditions constrain their trajectories, which affect both the two-phase flow calculations, and the evaluation of the slag accumulation. A harsh operation environment in the SRM with high temperatures and high pressure makes the measurement of the internal flow field quite difficult. The open literature includes only a few sets of experimental data that can be used to validate theoretical analyses and numerical calculations for the two-phase flow in a SRM. Therefore, mathematical models that calculate the trajectories of particles may reach different conclusions mainly because of the boundary conditions. A new method to determine the particle velocities on the solid propellant surface is developed in this study, which is based on the x-ray real-time radiography (RTR) technique, and is coupled with the two-phase flow numerical simulation. Other methods imitate the particle ejection from the propellant surface. The RTR high-speed motion analyzer measures the trajectory of the metal particles in a combustion chamber. An image processing software was developed for tracing a slug particle path with the RTR images in the combustion chamber, by which the trajectories of particles were successfully obtained.

Comparison of experimental data and numerical simulation of two-phase flow pattern in vertical minichannel

2012 ◽  
Vol 33 (1) ◽  
pp. 63-71
Author(s):  
Jarosław Sowiński ◽  
Marek Krawczyk ◽  
Marek Dziubiński
Keyword(s):  
Experimental Data ◽  
Numerical Simulation ◽  
Boundary Conditions ◽  
Flow Pattern ◽  
Two Phase Flow ◽  
Phase Flow ◽  
Computational Domain ◽  
Two Phase ◽  
Ansys Fluent ◽  
Satisfactory Description

Comparison of experimental data and numerical simulation of two-phase flow pattern in vertical minichannel The aim of the study was the implementation of a numerical simulation of the air-water two-phase flow in the minichannel and comparing results obtained with the values obtained experimentally. To perform the numerical simulations commercial software ANSYS FLUENT 12 was used. The first step of the study was to reproduce the actual research installation as a three-dimensional model with appropriate and possible simplifications - future computational domain. The next step was discretisation of the computational domain and determination of the types of boundary conditions. ANSYS FLUENT 12 has three built-in basic models with which a two-phase flow can be described. However, in this work Volume-of-Fluid (VOF) model was selected as it meets the established requirements of research. Preliminary calculations were performed for a simplified geometry. The calculations were later verified whether or not the simplifications of geometry were chosen correctly and if they affected the calculation. The next stage was validation of the chosen model. After positive verification, a series of calculations was performed, in which the boundary conditions were the same as the starting conditions in laboratory experiments. A satisfactory description of the experimental data accuracy was attained.

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