Computational Analysis of a Double Nozzle Structure Plasma Cutting Torch

Abstract

Double arcing phenomenon is a limit to increasing the capacity of the plasma cutting torch. In an attempt to enhance the ability of being invulnerable to the double arcing, a double nozzle structure is introduced in this paper. The reason why the double nozzle structure is less vulnerable to the double arcing phenomenon than single nozzle structure is explored. Double nozzle structure allows the longer nozzle which may cause stronger shock wave. In order to evaluate the influence of shock wave on the cutting ability, the influence of nozzle length on the double nozzle structure plasma arc is investigated. The modeling results show that the longer nozzle produces the stronger shock wave outside the nozzle outlet, but the energy flux and momentum flux become concentrated after the shock wave and increases with the increasing of nozzle length. So the double nozzle structure improves the cutting ability of the plasma torch and meanwhile be less vulnerable to the double arcing phenomenon.

On the Double-Arcing Phenomenon in a Cutting Arc Torch

“…11, right) shows that the signal has a very strong component at 150 Hz, which is the fundamental frequency of the power source ripple. This experimental result shows that the NLTE plasma inside the nozzle of a cutting torch results strongly affected by the arc voltage ripple, and thus it is far from the steady state, as it is usually assumed in the literature (e.g., Gonzalez-Aguilar et al, 1999;Freton et al, 2002;2003;Ghorui et al, 2007;Zhou et al, 2009, Guo et al, 2010. Such dynamics could explain the mechanism of formation of the non-destructive double arcing; as it is shown with detail in Fig.…”

“…Note that our hypothesis implies that the thickness of the space-charge layer (where almost all the electric field is concentrated) is shorter than the cold gas envelope (i.e., the electric field cannot penetrate deep inside such envelope), thus the average electric field in the nozzle vicinity rises ( VD ≈∆ ). The cold gas envelope hypothesis was recently adopted by Guo et al (2010). Its thickness was arbitrary defined as the contour corresponding to 7000 K (≈ 0.5 mm).…”

Numerical study of the effect of coflow argon jet on a laminar argon thermal plasma jet

“…Coflow argon jets also provide a cold boundary layer around the anode wall, which reduces the heat carried away by cooling water. In addition, coflow argon jets squeeze the arc column and raise the core temperature of thermal plasma jet, which contribute to improving the power density of thermal plasma [22][23][24].…”

Development of a new OpenFOAM solver for plasma cutting modeling

“…Along with these experimental investigations, several modellings of the process have been presented since the end of the 1990's [1,4,5,[9][10][11][12][13][14][15][16][17]. The first CFD study of a plasma cutting configuration has been proposed by González-Aguilar et al [10].…”