Mathematical model and laser‐scattering temperature measurements of a direct‐current plasma torch discharging into air

The numerical plasma torch model of D. A. Scott, P. Kovitya, and G. N. Haddad [J. Appl. Phys. 66, 5232 (1989)], in which both the arc and plume regions are included in the computational domain, has been extended to treat the effect of the mixing of the plasma gas with the ambient gas. Both laminar diffusion and turbulent mixing are considered. The predictions of the model are compared with laser‐scattering measurements of the temperature distribution in the plume of a plasma torch, for the case in which the plasma gas is argon and the ambient gas is air at atmospheric pressure. Good agreement is found between the measurements and the predictions of the model. The rapid decay in plume temperature away from the exit of the torch nozzle is shown to be mainly due to cooling by air entrained by turbulent mixing. The K‐e turbulence model is found to adequately approximate the turbulence phenonema involved.

[1]  Lawrence E. Cram,et al.  Statistical evaluation of radiative power losses from thermal plasmas due to spectral lines , 1985 .

[2]  Anthony B. Murphy,et al.  Temperature measurement in thermal plasmas by Rayleigh scattering , 1992 .

[3]  E. Pfender,et al.  Probe measurements in thermal plasma jets , 1988 .

[4]  P. Bradshaw,et al.  Turbulence Models and Their Application in Hydraulics. By W. RODI. International Association for Hydraulic Research, Delft, 1980. Paperback US $15. , 1983, Journal of Fluid Mechanics.

[5]  E. Pfender,et al.  Particle dynamics and particle heat and mass transfer in thermal plasmas. Part III. Thermal plasma jet reactors and multiparticle injection , 1987 .

[6]  P. Kovitya,et al.  Temperatures in the plume of a dc plasma torch , 1989 .

[7]  J. P. V. Doormaal,et al.  ENHANCEMENTS OF THE SIMPLE METHOD FOR PREDICTING INCOMPRESSIBLE FLUID FLOWS , 1984 .

[8]  L. Poladian,et al.  Departures from equilibrium in a free-burning argon arc , 1988 .

[9]  Peiyuan Zhu,et al.  A unified theory of free burning arcs, cathode sheaths and cathodes , 1992 .

[10]  J. Szekely,et al.  Fluid flow and heat transfer in plasma reactors—II. A critical comparison of experimentally measured and theoretically predicted temperature profiles in plasma jets in the absence and presence of side-stream injection , 1989 .

[11]  Suhas V. Patankar,et al.  A Calculation Procedure for Two-Dimensional Elliptic Situations , 1981 .

[12]  John D. Ramshaw,et al.  Computational fluid dynamics modeling of multicomponent thermal plasmas , 1992 .

[13]  Carl M. Penney,et al.  Light Scattering in Terms of Oscillator Strengths and Refractive Indices , 1969 .

[14]  C. B. Shaw,et al.  The temperature profiles in an argon plasma issuing into an argon atmosphere: A comparison of measurements and predictions , 1990 .

[15]  R. Penndorf,et al.  Tables of the Refractive Index for Standard Air and the Rayleigh Scattering Coefficient for the Spectral Region between 0.2 and 20.0 μ and Their Application to Atmospheric Optics , 1957 .

[16]  J. Szekely,et al.  Temperature and velocity fields in a gas stream exiting a plasma torch. A mathematical model and its experimental verification , 1982 .

[17]  P. Kovitya.  Thermodynamic and Transport Properties of Ablated Vapors of PTFE, Alumina, Perspex, and PVC in the Temperature Range 5000-30 000 K , 1984, IEEE Transactions on Plasma Science.

[18]  Julian Szekely,et al.  Some perspectives on the modeling of plasma jets , 1987 .

[19]  A. Murphy,et al.  Laser‐scattering measurement of temperature profiles of a free‐burning arc , 1992 .

[20]  John J. Lowke,et al.  Theory of free-burning arc columns including the influence of the cathode , 1992 .

[21]  J. Szekely,et al.  A comparison of experimental measurements and theoretical predictions regarding the behavior of a turbulent argon plasma jet discharging into air , 1990 .

[22]  Xianfan Xu,et al.  Numerical simulation of mixing of coaxial air flows with condensation , 1991 .

[23]  D. Evans.  The effect of impurities on the spectrum of laser light scattered by a plasma , 1970 .

[24]  E. Pfender,et al.  Entrainment of cold gas into thermal plasma jets , 1991 .

[25]  Ryoichi S. Amano,et al.  Numerical Study of Turbulent Axisymmetric Jets Impinging on a Flat Plate and Flowing Into an Axisymmetric Cavity , 1984 .

[26]  J. Szekely,et al.  A model of fluid, heat flow, and electromagnetic phenomena in a nontransferred arc plasma torch , 1991 .

[27]  J. Haidar,et al.  A method for the measurement of the cathode surface temperature for a high‐current free‐burning arc , 1993 .

[28]  S. Patankar.  Numerical Heat Transfer and Fluid Flow , 2018, Lecture Notes in Mechanical Engineering.

[29]  B. Launder,et al.  Mathematical Models of turbulence , 1972 .

[30]  G. Haddad,et al.  Rayleigh scattering measurements in a free-burning argon arc , 1988 .

[31]  E. Pfender,et al.  Nonequilibrium modeling of low-pressure argon plasma jets; Part I: Laminar flow , 1990 .

[32]  L. Cass,et al.  Turbulent mixing of an axisymmetric jet of partially dissociated nitrogen with ambient air. , 1966 .

[33]  M. Nallasamy,et al.  Turbulence models and their applications to the prediction of internal flows: a review , 1987 .