Computational study of high-speed plasma flow impinging on an enthalpy probe

Chang, C. H.; Ramshaw, John D.

doi:10.1007/bf01465215

Cited by 12 publications

(3 citation statements)

References 14 publications

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“…The exponent values in the above equations are m = 4.5 and n = 2. (20) Based on these functions, the conservation of mass and total enthalpy yield a system of two equations with two unknowns u m and T m . An iterative, method was used in order to deduce the centerline values of the velocity and temperature from this two equations system (14) m = R 0 ρ(r)u(r)2πr dr and…”

Section: Computational Domain and Boundary Conditionsmentioning

confidence: 99%

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Comparison between Two Turbulence Models and Analysis of the Effect of the Substrate Movement on the Flow Field of a Plasma Jet

El-Hadj

Messaoudene

2005

Plasma Chem Plasma Process

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In the first part of the present study, an appropriate inflow turbulent boundary condition is chosen. Then, a comparison is made between two turbulence models for a plasma jet discharged into air atmosphere. The plasma jet gas phase flow is predicted with the standard k−ε model and the RNG model of turbulence. Particles behavior is modeled using stochastic particles trajectories. A validation of the plasma jet model is made by comparison with experimental data.This part of the study shows that the flow features are better predicted with the RNG model. The choice of appropriate boundary conditions seems to be crucial for a better simulation of plasma thermal spraying. Afterwards, computations are performed for projection of Ni particles. It is found that the computed particles velocities and temperatures are also better predicted with the RNG model compared with the k−ε model. The second part of this study is concerned with the effect of the substrate movement on the gas flow field. This is performed in order to simulate a realistic coatings process where a relative movement between the torch and the substrate always exists. Three substrate velocities have been used and it is found that the flow fields are affected only very near the substrate wall.

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Section: Computational Domain and Boundary Conditionsmentioning

confidence: 99%

“…For this purpose, the standard wall functions are used for the velocity and temperature fields. At the nozzle exit, the velocity and temperature are assumed to be given by, (20) v = 0, w = 0, and u = u m · 1 − r R n (9)…”

Section: Computational Domain and Boundary Conditionsmentioning

confidence: 99%

Comparison between Two Turbulence Models and Analysis of the Effect of the Substrate Movement on the Flow Field of a Plasma Jet

El-Hadj

Messaoudene

2005

Plasma Chem Plasma Process

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“…They involve complex interactions between fluid dynamics, turbulent transport, thermal radiation, chemical reactions and phase changes. Thus, modelling of such processes has been a long-standing challenge [6][7][8][9][10].…”

Section: Introductionmentioning

confidence: 99%

Treatment of non-equilibrium phenomena in thermal plasma flows

Rat¹,

Murphy²,

Aubreton³

et al. 2008

J. Phys. D: Appl. Phys.

131

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Thermal plasma flows provide a uniquely high specific enthalpy source that is well suited to transformation of matter, often via phase changes. As a consequence, numerous thermal-plasma-based processes have been developed to, for example, destroy pollutants, modify surfaces (e.g. cutting and welding), synthesize nanostructures and deposit functionalized nanostructured coatings. In many cases, departures from equilibrium (both thermal and chemical) occur in regions of such plasmas; for example, in electrode erosion phenomena or in the injection of a liquid into a plasma jet. This paper reviews the treatment of non-equilibrium phenomena in thermal plasma flows, in particular the methods of calculation of the composition and transport coefficients of non-equilibrium plasmas, which are required for modelling the above processes. The focus is on two-temperature plasmas, in which electrons and heavy species are at different temperatures. Methods of calculation of the composition of plasmas both in local chemical equilibrium (LCE) and out of LCE are presented. A comparison of the different methods shows large discrepancies, even assuming LCE. Two-temperature transport coefficients obtained from simplified expressions, from the modified Chapman–Enskog method and from the Stefan–Maxwell relations are presented, as well as examples focusing on the influence of plasma composition. Different methods of calculation of the collision integrals required in determining the transport coefficients are also reviewed. Particular attention is paid to diffusion, in particular to the combined diffusion coefficient method, which simplifies treatment of plasmas in LCE. The method of calculation of the reactive thermal conductivity and the influence of excited states on transport coefficients are also addressed in some detail.

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Direct Current Plasma Spraying: Diagnostics and Process Simulation

et al. 2006

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This paper presents our current knowledge in direct current (d.c.) plasma spraying with conventional stick‐type cathode plasma torches. It deals with the experimental methods and models used to better understand and /or control the characteristics of plasma jet, particles in‐flight and at impact. The first part refers to measurements and on‐line monitoring or control. The emphasis is on (i) the effect of arc root fluctuations and electrode wear on particle treatment and coating formation; (ii) the drastic importance of the interface between the flattening particles and substrate. The second part examines the models used to predict gas flow field and particle parameter distributions at impact. It presents: (i) steady and 2‐D models that allow optimal experimental design with a limited number of experiments as well as education and training; (ii) 3‐D and time dependent models that make it possible to take account of the arc root fluctuation at the anode and a stochastic and time‐dependent particle injection description.

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Computational study of high-speed plasma flow impinging on an enthalpy probe

Cited by 12 publications

References 14 publications

Comparison between Two Turbulence Models and Analysis of the Effect of the Substrate Movement on the Flow Field of a Plasma Jet

Comparison between Two Turbulence Models and Analysis of the Effect of the Substrate Movement on the Flow Field of a Plasma Jet

Treatment of non-equilibrium phenomena in thermal plasma flows

Direct Current Plasma Spraying: Diagnostics and Process Simulation

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