Comparative study of turbulence models on highly constricted plasma cutting arc

Abstract

Plasma cutting arc characteristics are investigated for different turbulence models, i.e. the Reynolds stress model (RSM), the k–ϵ model and its variants, the renormalization group (RNG) k–ϵ model, the RNG k–ϵ model taking into account the low Reynolds number effect and the realizable k–ϵ model. The results of the RSM and the RNG k–ϵ model taking into account the low Reynolds number effect are in reasonable agreement with experiment. They both predict very close voltage, shock wave location and temperature variation along the axis to experiment. On the other hand, the other three models overestimate the turbulence effects and predict much lower velocity and temperature, especially the standard k–ϵ model, which predicts that the temperature is about 10 000 K lower than the experiment in certain plasma jet regions.

Three-Dimensional Unsteady MHD Modeling of a Low-Current High-Voltage Nontransferred DC Plasma Torch Operating With Air

“…Numerous fluid models have been reported in the literature mostly on direct current (DC) arc discharge modeling using Digital Object Identifier high current above 100 A [1], [2] including: free burning arcs [3], [4], transferred arcs [5]- [7] and non-transferred arcs [8]- [11]. Many DC arc plasma torches models have been developed for different applications [12] as: cutting [13], welding [14], deposition and spraying [8]- [11], [15], [16], steelmaking [7], waste disposal [17] and ultra fine particle production [18]. These thermal plasmas generally work under low-medium voltage between 30 and 500 V [2].…”

“…Trelles et al [21] and Park et al [22] who developed non-LTE (NLTE) models in argon. The calculations are often realized in a simple gas, mainly argon [4], [15], [18], [20] but also nitrogen [5], pure oxygen [13], or a gas mixture: air [17], Ar/H 2 [8], Ar/N 2 [9]- [11]. The main focuses of arc plasma torch modeling are the arc root displacement and attachment [16], [17], and the metal electrode evaporation [14], [16].…”

“…The main focuses of arc plasma torch modeling are the arc root displacement and attachment [16], [17], and the metal electrode evaporation [14], [16]. Although the laminar flow regime is commonly used for modeling plasma torch [6], [8], [10], [17], [23], literature reports few studies using turbulent k-ǫ model [15], [18], Rij-ǫ and low-Re models [24], comparing laminar to standard k-ǫ model [25], or comparing several turbulent models (standard k-ǫ, RNG k-ǫ, realizable k-ǫ) [13]. For several years, researches carried out at CEP (Center for Energy and Processes, MINES ParisTech) in the field of hydrocarbons reforming led to the development of a very peculiar DC plasma torch technology operating under low current -high voltage conditions: typically in the range 400 mA and 2 kV respectively.…”

Effects of Nozzle Length and Process Parameters on Highly Constricted Oxygen Plasma Cutting Arc

“…This restricts the validity of our results at these zones (e.g. large radial temperature gradient in the fringe of arc [17]), but the qualitative behavior of our simulations will be reasonably expected to still be valid. (e) The arc radiation is taken into account by net emission coefficient.…”

Basic knowledge on radiative and transport properties to begin in thermal plasmas modelling

“…Usually, the system is composed of three common conservation equations: mass, momentum and energy coupled to the ad hoc Maxwell's equations [1][2][3][4] (depending on the problem). To these equations, a set of complementary equations is added to take into account other electrical or thermal phenomena depending on the application: 5-7 turbulence effects, 8 deviations from chemical equilibrium or thermal equilibrium, 9 modelling of multiphase flows, role of the shielding gases, 10 interactions arcanode/cathode, 11-13 interaction plasma-walls and/or plasma-particles, [14][15][16] diffusion of the gaseous species or particles in the plasma, 17 formation of fume or nucleation/growth/aggregation of particles 18,19 are some examples. The equations of the system can be written as a convection-diffusion equation (1) for a variable φ.…”