Nonequilibrium modeling of low-pressure argon plasma jets; Part II: Turbulent flow

This paper presents a two-temperature model for compressible plasma flows. This study concentrates on the behaviour of the plasma jet in the expansion region. The conditions used correspond to the conditions of low-pressure plasma spraying, with slightly supersonic conditions with thermal and chemical non-equilibrium. The flow dynamics results are analysed with different turbulence models and appear to be consistent with results previously published by the authors [3] on the dynamics of low-temperature air jets and favour the Reynolds stress turbulence model. Chemical as well as thermal non-equilibrium are studied.

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“…• The total energy equation is solved for heavy particles, whereas in some previous studies [7,20,21] the thermal part was considered.…”

Section: Discussionmentioning

confidence: 99%

A self-consistent two-temperature model for the computation of supersonic argon plasma jets

Bartosiewicz

Proulx

Mercadier

2002

J. Phys. D: Appl. Phys.

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“…The expansion into a low-pressure (not vacuum) atmosphere, however, consists of the region of adiabatic expansion followed by a stationary normal shock wave and a subsonic relaxation zone (figure 1). We can conclude that the supersonic plasma expansion into lowpressure atmosphere represents a combination of three sorts of flows: a plasma expansion into vacuum [31][32][33][34], a shock wave formation [20,35,36] and a subsonic plasma jet [37][38][39][40][41]. In our simulations, however, we do not separate the regions of these flows.…”

Section: Introductionmentioning

confidence: 94%

Stationary supersonic plasma expansion: continuum fluid mechanics versus direct simulation Monte Carlo method

Selezneva

Boulos

Sanden

et al. 2002

J. Phys. D: Appl. Phys.

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Supersonically expanding stationary thermal plasma, formed by a thermal cascaded arc is studied. Due to the low chamber pressure (20-100 Pa) the results of continuum mechanics model can be doubtful. This is why these results are validated against kinetic Monte Carlo simulation and experimental data obtained by means of laser induced fluorescence. The analysis proves that continuum mechanics is still applicable for the velocity and temperature field predictions downstream of the shock region. However, the shock formation and some non-equilibrium effects typical for supersonic flow can be correctly studied only with the help of kinetic simulations. We show that the errors in the results using continuum mechanics can be attributed to the presence of flow gradients. These errors diminish when the shock regions are thickened due to rarefaction, viscosity and heat conductivity. Besides, both methods show that the effect of the chamber geometry on the plasma flow field is important.

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“…During several decades supersonic plasma jets have been investigated with the help of various analytical, numerical and experimental methods [4][5][6][7][8]. Better understanding of the processes governed the nonisobaric supersonic plasma jet flows was reached studying the plasma nozzle [9][10][11][12], plasma jet [13][14][15][16][17][18][19] flows and supersonic gas jet flows [20][21][22]. Among the experimental studies we can mention the measurements of the electron number density and electron temperature in the expanding cascaded arc [7] and OES study of the supersonic jets of plasma generated by direct current arc [23][24][25].…”

Section: Introductionmentioning

confidence: 99%

Spectroscopic validation of the supersonic plasma jet model

Selezneva

Sember

Gravelle

et al. 2002

J. Phys. D: Appl. Phys.

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Optical emission spectroscopy is applied to validate numerical simulations of supersonic plasma flow generated by induction torch with a convergent-divergent nozzle. The plasmas exhausting from the discharge tube with the pressure 0.4-1.4 atm. through two nozzle configurations (the outlet Mach number equals 1.5 and 3) into low-pressure (1.8 kPa) chamber are compared. Both modelling and experiments show that the effect of the nozzle geometry on physical properties of plasma jet is significant. The profiles of electron number density obtained from modeling and spectroscopy agree well and show the deviations from local thermodynamic equilibrium. Analysis of intercoupling between different sorts of nonequilibrium processes is performed. The results reveal that the ion recombination is more essential in the nozzle with the higher outlet number than in the nozzle with the lower outlet number. It is demonstrated that in the jets the axial electron temperature is quite low (3000-8000 K). For spectroscopic data interpretation we propose a method based on the definition of two excitation temperatures. We suppose that in mildly under expanded argon jets with frozen ion recombination the electron temperature can be defined by the electronic transitions from level 5p (the energy E = 14.5 eV) to level 4p (E = 13.116 eV). The obtained results are useful for the optimization of plasma reactors for plasma chemistry and plasma processing applications.

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Nonequilibrium modeling of low-pressure argon plasma jets; Part II: Turbulent flow

Abstract: The nonequilibrium behavior of low-pressure, turbulent plasma jets has been tested using the k-e turbulence model and the model described in the previous paper. It also has been shown that nonequilibrium effects cannot be excluded in the case of turbulent jets.

Cited by 30 publications

References 2 publications

A self-consistent two-temperature model for the computation of supersonic argon plasma jets

A self-consistent two-temperature model for the computation of supersonic argon plasma jets

Stationary supersonic plasma expansion: continuum fluid mechanics versus direct simulation Monte Carlo method

Spectroscopic validation of the supersonic plasma jet model

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