Experimental and theoretical study of a stationary high-current arc in a supersonic nozzle flow

Hermann, W.; Kogelschatz, U.; Niemeyer, L.; Ragaller, K.; Schade, E.

doi:10.1088/0022-3727/7/12/317

Cited by 70 publications

(32 citation statements)

References 18 publications

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“…We will consider in this work only straight nozzles (R N = const.). No mixing between the hot arc and the cold gas is assumed, since it has been shown [7] that turbulence (leading to a mixing between arc and gas) develops in the diverging region of the nozzle. A sketch of the flow geometry is shown in Fig.…”

Section: Equations Of the Modelmentioning

confidence: 99%

Hydrodynamic model for the plasma-gas flow in a cutting torch nozzle

Kelly¹,

Minotti²,

Prevosto³

et al. 2004

Braz. J. Phys.

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We present a simple hydrodynamic model to obtain the profiles of the relevant physical quantities along a nozzle of arbitrary cross-section in a cutting torch. The model uses a two-zone approximation (a hot central plasma carrying the discharge current wrapped by a relatively cold gas which thermally isolates the nozzle wall from the plasma). Seeking for a solution with sonic conditions at the nozzle exit, the model allows expressing all the profiles in terms of the externally controlled parameters of the torch (geometry of the torch, discharge current, mass flow of the gas and plenum pressure) and the values of the arc and gas temperatures at the nozzle entrance. These last two values can be estimated simply appealing to energy conservation in the cathode-nozzle region. The model contains additional features compared with previous reported models, while retaining simplicity. The detailed consideration of an arc region coupled to the surrounding gas dynamics allows determining voltage drops and consequent delivered power with less assumptions than those found in other published works, and at the same time reduces the set of parameters needed to determine the solution.

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Section: Equations Of the Modelmentioning

confidence: 99%

Hydrodynamic model for the plasma-gas flow in a cutting torch nozzle

Kelly¹,

Minotti²,

Prevosto³

et al. 2004

Braz. J. Phys.

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“…Research which characterized the static u(i)-curve of axially blown arcs was already started half a century ago, extensive work was done by Tuma, Lowke, Niemeyer, Ragaller and many others [6], [7]. The black-box models of Mayr and Schwarz are also still valuable tools, despite their age [8], [9].…”

Section: Introductionmentioning

confidence: 99%

Determination of Axial Electric Field Distribution in Blown Arcs With Differential Method

Bort

Franck

2019

IEEE Trans. Plasma Sci.

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DC switchgear using gas circuit breakers (CB) in parallel to a LC-resonant path is used for decades already. This "passive oscillation" topology relies on negative damping of the oscillating current, made possible by the fact that the voltage drop over the CB decreases with increasing current. This concept is cheap and reliable, since it does not require any active components besides the mechanical breaker. However, the achievable breaking times and maximum interruptable current amplitude highly depend on the u(i) characteristic of the axially blown arc inside the breaker. Improvements to the breaking chamber could move the maximal breakable current to higher values, and reduce the time to current zero (CZ). Analyzing which parameters influence the arc voltage is crucial for this optimization. Knowing which axial segments contribute how much to the total arc voltage enables a deeper understanding and possibilities to improve performance. Direct measurements of voltages inside the nozzle of a CB are not feasible, therefore an indirect method was developed. The contact positions in a model circuit breaker were varied systematically, and by evaluating the u(i) curves of 13 different configurations, the voltage drop of eight segments of 2 cm length was calculated. It is shown that most of the voltage drops over the converging nozzle part, where gas density and acceleration is high. These segments also exhibit beneficial behavior, with du/di being negative. The method was validated by comparing the extracted results with suitable direct measurements.

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“…The experimental data of Hermann et al 3 stated that, near zero current, the radiation term U can be neglected compared to the ohmic heating term aE 2 .…”

Section: The Arc Equationmentioning

confidence: 99%

Experimental and theoretical study of a direct-current arc in an orifice nozzle flow

Whang

Nagamatsu

1985

AIAA Journal

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To increase the basic knowledge about the interaction between an arc near zero current and flows affected by strong shock waves, an investigation was conducted to determine the d.c. arc characteristics at a current of approximately 100 A in an orifice nozzle. Various nozzle pressure ratios were used to produce subsonic and supersonic flows. Cold-flow measurements were used to calculate the arc electrical parameters based on the arc energy integral theory. The calculated results agreed reasonably well with the experimental measurements. It can be concluded that the convection cooling of the arc is the dominant arc cooling process for most currents. Nomenclature= constants in mass flux equation C = sonic velocity C p = specific heat at constant pressure E = electric field strength e = thermal, kinetic, and potential energy per unit mass h = enthalpy / = current j = current density K M P R r r 0 R(z) T T 0

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Experimental and theoretical study of a stationary high-current arc in a supersonic nozzle flow

Cited by 70 publications

References 18 publications

Hydrodynamic model for the plasma-gas flow in a cutting torch nozzle

Hydrodynamic model for the plasma-gas flow in a cutting torch nozzle

Determination of Axial Electric Field Distribution in Blown Arcs With Differential Method

Experimental and theoretical study of a direct-current arc in an orifice nozzle flow

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