Non-equilibrium modelling of transferred arcs

Haidar, J

doi:10.1088/0022-3727/32/3/014

Cited by 119 publications

(97 citation statements)

References 15 publications

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“…This means that the central core of the lightning channel has been intensively heated and the LTE is maintained (Gallimberti and Stangherlin 1986). The deviation from LTE in free-burning arcs as discussed by Haidar (1999) was caused by local effects close to the cathode. The implication of the assumption of LTE is that there is a unique temperature for every kind of particle, which makes it possible to treat the arc plasma as a one-phase medium having a well defined velocity, pressure and temperature (or enthalpy) at each point.…”

Section: Arc Column Modelmentioning

confidence: 97%

The lightning swept stroke along an aircraft in flight. Part I: thermodynamic and electric properties of lightning arc channels

Larsson¹,

Lalande²,

Bondiou-Clergerie

et al. 2000

J. Phys. D: Appl. Phys.

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General rights Copyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights.• Users may download and print one copy of any publication from the public portal for the purpose of private study or research.• You may not further distribute the material or use it for any profit-making activity or commercial gain • You may freely distribute the URL identifying the publication in the public portal Abstract. During a lightning strike to an aircraft in flight, the lightning channel becomes deformed in the airflow and displaced along the aircraft, a so-called swept stroke. The deformation and the displacement are caused by the interaction between the aerodynamic flow and the plasma properties of the channel together with the properties of the surface. The main part of the lightning current is a continuous current with a magnitude of hundreds of amperes and a duration of hundreds of milliseconds. The objective of this article is to analyse the properties of the lightning channel during this continuous current phase in order to parametrize them; this parametrization is used in a companion paper (Larsson et al J. Phys. D: Appl. Phys. 33 1876-83) for complete swept-stroke simulations. A model of the thermodynamic evolution of a lightning channel during its continuous current phase is developed and numerically solved. In this model, the channel is assumed to have axial symmetry. A quantitative analysis of the influence of failing axial symmetry is also included. The main conclusions are that the steady-state conditions are rapidly reached and that the channel can be considered to be a free-burning arc subjected to increased thermal losses due to transverse aerodynamic flow.

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Section: Arc Column Modelmentioning

confidence: 97%

The lightning swept stroke along an aircraft in flight. Part I: thermodynamic and electric properties of lightning arc channels

Larsson¹,

Lalande²,

Bondiou-Clergerie

et al. 2000

J. Phys. D: Appl. Phys.

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“…Substituting (4), (6), (7) into equation (1), we obtain (8) where dn m0 /dt is the substantial derivative;…”

Section: Mzmentioning

confidence: 99%

“…In the first publications, devoted to mathematical simulation of the processes of heat, mass and charge transfer in refractory cathode arcs [2][3][4][5][6][7][8][9][10], arc plasma was assumed to be single-component, i.e. containing atoms and ions of just the shielding gas.…”

mentioning

confidence: 99%

Simulation of electric arc with refractory cathode and evaporating anode

Krikent¹,

Krivtsun²,

Demchenko³

2014

The Paton Welding J.

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Equation of convective diffusion of ionized metal vapour in arc plasma, allowing for the difference in coefficients of diffusion of atoms, single-and double-charged metal ions, presence of thermodiffusion flows of metal particles, as well as ion drift in the electric field, was proposed to more precisely define the earlier developed complex model of the processes of energy, mass and charge transfer in the column and anode region of electric arc with refractory cathode and evaporating anode, running in inert gas. Based on the thus precised complex mathematical model, numerical analysis of the influence of diffusion-induced evaporation of anode material (Fe) on heat, gas-dynamic and electromagnetic characteristics of multicomponent plasma of the column and anode region of stationary electric arc with refractory cathode (W) at its running in inert gas (Ar) was performed. An essential influence of metal surface temperature distribution in the region of anode binding of the arc on distribution of temperature and electric current density in near-anode plasma, as well as on distributed and integral characteristics of its thermal impact on evaporating anode surface, is shown. 18 Ref., 12 Figures. K e y w o r d s : electric arc, refractory cathode, evaporating anode, arc column, anode region, multicomponent plasma, metal vapour, diffusion, mathematical simulationElectric arc plasma in inert-gas nonconsumableelectrode welding, as a rule, is multicomponent, as alongside shielding gas particles, it contains atoms and ions of metal vapour coming to the arc gap due to evaporation of anode metal from weld pool surface. Presence of an even small amount of metal component in inert gas arc plasma has an essential influence on its ionization composition, thermodynamic, transport and optical properties. It leads to a significant difference of heat, electromagnetic and gas-dynamic characteristics of plasma in near-anode zone of arc column in nonconsumable-electrode welding from respective characteristics of arc discharge with refractory cathode and nonevaporating, for instance, water-cooled anode. Characteristics of welding arc anode region, determining the conditions of thermal and electromagnetic interaction of the arc with metal being welded and, consequently, nature of its penetration, are also different [1].In the first publications, devoted to mathematical simulation of the processes of heat, mass and charge transfer in refractory cathode arcs [2-10], arc plasma was assumed to be single-component, i.e. containing atoms and ions of just the shielding gas. Such idealization did not incorporate any conditions of running of real welding arcs, and required further improvement of mathematical models of the arc, in order to allow for a number of additional physical factors, related to multicomponent nature of arc plasma. Publications devoted to allowing for evaporation of anode material in simulation of nonconsumableelectrode welding arc, appeared in the world scientific literature comparatively recently [11][12][13]. When describing...

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“…This has been shown to be a valid assumption in the main body of the arc, both experimentally [20,21] and theoretically [22]. Deviations from LTE can occur close to the cathode [23] and the anode [24,25], and also in the fringes in the arc [26]. To take all the effects into account would require treating the transport and reactions of each plasma species separately.…”

Section: Numerical Modelmentioning

confidence: 99%

Three-dimensional modelling of arc behaviour and gas shield quality in tandem gas–metal arc welding using anti-phase pulse synchronization

Schnick¹,

Wilhelm²,

Lohse³

et al. 2011

J. Phys. D: Appl. Phys.

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The paper presents a transient three-dimensional model of an anti-phase-synchronized pulsed tandem gasmetal arc welding process, which is used to analyze arc interactions and their influence on the gas shield flow. The shielding gases considered are pure argon and a mixture of argon with 18% CO 2. Comparison of the temperature fields predicted by the model with high-speed images indicates that the essential features of the interactions between the arcs are captured. The paper demonstrates strong arc deflection and kinking, especially during the low-current phase of the pulse, in agreement with experimental observations. These effects are more distinct for the argon mixture with 18% CO 2 . The second part of the paper demonstrates the effects of arc deflection and instabilities on the shielding gas flow and the occurrence of air contamination in the process region. The results allow an improved understanding of the causes of periodic instabilities and weld seam imperfections such as porosity, spatter, heat-tint oxidation and fume deposits.

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Non-equilibrium modelling of transferred arcs

Cited by 119 publications

References 15 publications

The lightning swept stroke along an aircraft in flight. Part I: thermodynamic and electric properties of lightning arc channels

The lightning swept stroke along an aircraft in flight. Part I: thermodynamic and electric properties of lightning arc channels

Simulation of electric arc with refractory cathode and evaporating anode

Three-dimensional modelling of arc behaviour and gas shield quality in tandem gas–metal arc welding using anti-phase pulse synchronization

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