Modeling of Multi-Phase Flow in Electro-Chemical Machining: One-Way Coupling Versus Two-Way Coupling

Electro-Chemical Machining (ECM) is an advanced machining technology. It has been applied to highly specialized fields such as aerospace, aeronautics and medical industries. However, it still has some problems to be overcome. The efficient tool-design, electrolyte processing, and disposal of metal hydroxide sludge are the typical issues. To solve such problems, CFD is considered to be a powerful tool in the near future. However, the numerical method that can satisfactorily predict ECM process has not been established because of the complex flow natures. In the present study, we investigate the modeling of the two-phase flow (i.e. fluid and hydrogen bubbles) in ECM process. First, we present two models to calculate flow fields in ECM process. One is based on one-way coupling method, neglecting the effect from gas-phase to liquid-phase. The other takes account of the interaction between gas and liquid phases, namely two-way coupling method. In the later method, assuming that electrolyte and hydrogen bubbles have same velocity, we simplified the governing equations with Low Mach number approximation. We simulated ECM process for a flat plate channel configuration. And, we verified the present models by comparing the numerical result with the experimental data.

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Investigating Behavior of Hydrogen Bubbles in Electro-Chemical Machining

Volume 1: Symposia, Parts A and B ◽

10.1115/fedsm2008-55296 ◽

2008 ◽

Author(s):

Ryo Tsuboi ◽

Makoto Yamamoto

Keyword(s):

Suction Side ◽

Coupling Method ◽

Stream Line ◽

Uniform Density ◽

Complex Flow ◽

Low Velocity ◽

Pressure Poisson Equation ◽

Liquid Phases ◽

Hydrogen Bubbles ◽

Advanced Machining

Electro-Chemical Machining (ECM) is an advanced machining technology and has been applied to highly specialized fields, such as aerospace, aeronautics, and medical industries. However, some problems remain to be solved. The efficient tool-design, electrolyte processing, and disposal of metal hydroxide sludge are typical problems. To solve such problems, CFD is thought to have potential as a powerful tool. However, a numerical method that can satisfactorily predict the ECM process has not been established because of the complex flow natures. In a previous study, we presented a new model to simulate the flow fields in an ECM process. This model is based on a two-way coupling method, taking the interaction between gas and liquid phases into account. In this coupling method, we assumed that electrolyte and generated hydrogen bubbles over a cathode surface have the same velocity. Therefore, we could simplify the governing equations. Since the flow field had a non-uniform density distribution due to hydrogen bubbles, a low Mach number approximation was applied to solve the pressure Poisson equation. In the present study, we calculate hydrogen bubble trajectories and investigate the distribution and a behavior of hydrogen bubbles. Since hydrogen bubbles follow fluid well, they travel along the stream line. This is because hydrogen bubbles have small density. In the results, around the low velocity region, hydrogen bubbles remain there with making the spiral structure. Hydrogen particles remain more in the suction side than that in the pressure side of the blade.

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Modelling of Three-Phase Flow in Electro-Chemical Machining

Volume 2: Fora ◽

10.1115/fedsm2005-77435 ◽

2005 ◽

Author(s):

Ryo Tsuboi ◽

Kazuyuki Toda ◽

Makoto Yamamoto ◽

Ryuki Nohara ◽

Dai Kato

Keyword(s):

Model Parameters ◽

Phase Flow ◽

Complex Flow ◽

Efficient Tool ◽

Hydrogen Bubbles ◽

Three Phase ◽

Three Phase Flow ◽

Advanced Machining ◽

Channel Configuration ◽

Near Future

Electro-Chemical Machining (ECM) is an advanced machining technology. It has been applied to highly specialized fields such as aerospace, aeronautics and medical industries. However, it still has some problems to be overcome. The efficient tool-design, electrolyte processing, and disposal of metal hydroxide sludge are the typical issues. To solve such problems, CFD is considered to be a powerful tool in the near future. However, the numerical method that can satisfactorily predict the flow has not been established because of the complex flow natures. In the present study, we investigate the modelling of the three-phase flow (i.e. fluid, hydrogen bubble and metal sludge) in ECM process. First, the developed code is applied to the two-dimensional channel configuration. The interactions among three-phases and the dissolved wall are simulated, to verify the modelling and to determine the model parameters, Next, the sinusoidal channel is machined by our code. It is confirmed that hydrogen bubbles in the separation region suppress the dissolution of the wall, and make the final wall shape be wavy. Through this study, it is exhibited that our developed model and code are sound and useful for simulating ECM process.

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Three-Dimensional Two-Phase Flow Simulations of Water Braking Phenomena for High-Speed Test Track Sled

10.1115/fedsm2021-65799 ◽

2021 ◽

Author(s):

Jose Terrazas ◽

Arturo Rodriguez ◽

Vinod Kumar ◽

Richard Adansi ◽

V. M. Krushnarao Kotteda

Keyword(s):

High Speed ◽

Three Dimensional ◽

Initial Boundary ◽

Phase Flow ◽

Momentum Exchange ◽

Two Phase ◽

Test Track ◽

Speed Test ◽

Liquid Phases ◽

Multi Phase Flow

Abstract Specializing in high-speed testing, Holloman High-Speed Test Track (HHSTT) uses a process called ‘water braking’ as a method to bring vehicles at the test track to a stop. This method takes advantage of the higher density of water, compared to air, to increase braking capability through momentum exchange. By studying water braking using Computational Fluid Dynamics (CFD), forces acting on track vehicles can be approximated and prepared for prior to actual test. In this study, focus will be made on the brake component of the track sled that is responsible for interacting with the water for braking. By discretizing a volume space around our brake, we accelerate water and air to relatively simulate the brake engaging. The model is a multi-phase flow that uses the governing equations of gas and liquid phases with the finite volume method, to perform 3D simulations. By adjusting the inflow velocity of air and water, it is possible to simulate HHSTT sled tests at various operational speeds. In the development of the 3D predictive model, convergence issues associated with the numerical mesh, initial/boundary conditions, and compressibility of the fluids were encountered. Once resolved, the effect of inflow velocities of water and air on the braking of the sled are studied.

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Predicting Compositional Two-Phase Flow Behavior in Pipelines

Journal of Energy Resources Technology ◽

10.1115/1.3231266 ◽

1986 ◽

Vol 108 (3) ◽

pp. 207-210 ◽

Cited By ~ 7

Author(s):

H. Furukawa ◽

O. Shoham ◽

J. P. Brill

Keyword(s):

Mass Transfer ◽

Computational Algorithm ◽

Two Phase Flow ◽

Flow Behavior ◽

Phase Flow ◽

Temperature Profiles ◽

Balance Equations ◽

Two Phase ◽

Liquid Phases ◽

Retrograde Condensation

A computational algorithm for predicting pressure and temperature profiles for compositional two-phase flow in pipelines has been developed. The algorithm is based on the coupling of the momentum and energy balance equations and the phase behavior of the flowing fluids. Mass transfer between the gas and the liquid phases is treated rigorously through flash calculations, making the algorithm capable of handling retrograde condensation. Temperatures can be predicted by applying the enthalpy balance equation iteratively. However, it was found that the explicit Coutler and Bardon analytical solution for the temperature profile yields nearly identical results for horizontal and near horizontal flow.

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A review of multiphase flow and deposition effects in film-cooled gas turbines

Thermal Science ◽

10.2298/tsci180108258w ◽

2018 ◽

Vol 22 (5) ◽

pp. 1905-1921 ◽

Cited By ~ 2

Author(s):

Jin Wang ◽

Milan Vujanovic ◽

Bengt Sunden

Keyword(s):

Film Cooling ◽

Gas Turbines ◽

Particle Deposition ◽

Experimental Studies ◽

Turbulence Models ◽

Phase Flow ◽

Two Phase ◽

Film Cooling Effectiveness ◽

Factors Affecting ◽

Multi Phase Flow

This paper presents a review of particle deposition research in film-cooled gas turbines based on the recent open literature. Factors affecting deposition capture efficiency and film cooling effectiveness are analyzed. Experimental studies are summarized into two discussions in actual and virtual deposition environments. For investigation in virtual deposition environments, available and reasonable results are obtained by comparison of the Stokes numbers. Recent advances in particle deposition modeling for computational fluid dynamics are also reviewed. Various turbulence models for numerical simulations are investigated, and solutions for treatment of the particle sticking probability are described. In addition, analysis of injecting mist into the coolant flow is conducted to investigate gas-liquid two-phase flow in gas turbines. The conclusion remains that considerable re-search is yet necessary to fully understand the roles of both deposition and multi-phase flow in gas turbines.

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CFD Prediction of Safety Valve Disc Forces Under Two Phase Flow Conditions

Volume 3A: Design and Analysis ◽

10.1115/pvp2018-84745 ◽

2018 ◽

Cited By ~ 1

Author(s):

William Dempster ◽

Moftah Alshaikh

Keyword(s):

Two Phase Flow ◽

Safety Valve ◽

Phase Flow ◽

Complex Flow ◽

Two Phase ◽

Wide Range ◽

Valve Disc ◽

Valve Dynamics ◽

Inlet Conditions ◽

Industrial Refrigeration

At present there are very few published works on prediction based methods to establish the forces that act on safety valves during two-phase operation. This means that the valve dynamics and resulting opening and closure are uncertain for a wide range of complex flow applications. This paper describes a study whereby a safety valve, primarily developed for the industrial refrigeration sector is investigated for a range of steady state high gas mass fraction inlet conditions, (gas mass quality 1-0.2) and the disc force characteristics measured for valve choked conditions. The highly compressible two phase flow processes are modelled using an Euler–Euler two fluid CFD approach and the results compared with the experiments. Results indicate that CFD approaches can reasonably capture the key processes but deficiencies exist due to the prediction of two phase built up backpressure in the valve. The methods and data trends are discussed to show the effectiveness of current modelling approaches.

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Research Analysis and Experiment Study on Flow Field of Hydrodynamic Coupling

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.418-420.2006 ◽

2011 ◽

Vol 418-420 ◽

pp. 2006-2011

Author(s):

Rui Zhang ◽

Cheng Jian Sun ◽

Yue Wang

Keyword(s):

Flow Field ◽

Cfd Simulation ◽

Two Phase Flow ◽

Three Dimensional ◽

Internal Flow ◽

Phase Flow ◽

Complex Flow ◽

Two Phase ◽

Operation Conditions ◽

Hydrodynamic Coupling

CFD simulation and PIV test technology provide effective solution for revealing the complex flow of hydrodynamic coupling’s internal flow field. Some articles reported that the combination of CFD simulation and PIV test can be used for analyzing the internal flow field of coupling, and such analysis focuses on one-phase flow. However, most internal flow field of coupling are gas-fluid two-phase flow under the real operation conditions. In order to reflect the gas-fluid two-phase flow of coupling objectively, CFD three-dimensional numerical simulation is conducted under two typical operation conditions. In addition, modern two-dimensional PIV technology is used to test the two-phase flow. This method of combining experiments and simulation presents the characteristics of the flow field when charging ratios are different.

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