3-D Hydrodynamic Model of Metal Droplet Sputtering and Molten Pool Formation Under Electric Arc
01 Oct 2018-
TL;DR: In this paper, a 3D hydrodynamic model has been developed to describe the formation process of molten metal liquid drop edge ejection and molten pool in the initial axisymmetric stage.
Abstract: Material erosion caused by the molten metal liquid droplet ejection is one of the serious problem for contacts used in heavy and medium load conditions. To understand the complex nature of the metal droplet sputtering and molten pool formation under electric arc, a 3-D hydrodynamic model has been developed to describe the formation process of molten metal liquid drop edge ejection and molten pool in the initial axisymmetric stage. The model includes the melting process of pure copper electrode and Marangoni effect of the fused metal. It is carried out with a Multiphysics FEM program COMSOL based on Navier-Stokes equations for incompressible viscous fluid, and the simplified electric arc interacting with the electrode is exerted by pressure and heat flux dissipated on the electrode. The method of combining moving mesh and automatic re-mesh can solve the deformation problem of fused metal. The simulated molten pool metal liquid surface deformation and metal droplet sputtering are presented by the temperature and velocity distribution sequences.
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09 Feb 2021
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TL;DR: In this paper, the electrical resistivities and equation of state of liquid copper and aluminum have been measured to temperatures of 4500 and 4000 K, respectively, using the isobaric expansion apparatus.
Abstract: The electrical resistivity and equation of state of liquid copper and aluminum have been measured to temperatures of 4500 and 4000 K, respectively, using the isobaric expansion apparatus. The specific heats for the liquid are in good agreement with extrapolation of the 1973 Hultgren tables. The electrical resistivities are presented both with and without correction for thermal expansion. Both resistivity and thermal expansion results for aluminum are compared with the predictions of pseudopotential calculations. The specific volumes observed for both metals are less than those reported in the literature, apparently because of axial hydrodynamic displacement. In addition, sudden rapid acceleration in sample growth rate with a corresponding rapid rise in resistivity were observed.
107 citations
"3-D Hydrodynamic Model of Metal Dro..." refers background in this paper
...The physics parameters of copper are taken from the literatures [20, 21], ) is the...
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TL;DR: In this paper, a statistical model of a vacuum arc is used to interpret the effect of the spontaneous extinction of an arc, and it is shown that an arc is self-sustained due to the explosive electron emission processes initiated on the interaction of the cathode plasma either with nonmetal inclusions present in the cathodes surface (first-type spots) or with liquid metal jets ejected from the zone of an active cathode spot (second type spots).
Abstract: In this paper, we review the state of the art in studying the physical processes that occur in the cathode spots of vacuum arcs. The now available experimental data are interpreted in the context of the ecton mechanism of the operation of vacuum arc cathode spots. Central in this mechanism is the explosive electron emission, a phenomenon discovered by the author and his co-workers in the mid-1960s while studying high-voltage pulsed vacuum breakdown. In the light of the ecton mechanism, the cathode spot of a vacuum arc consists of individual cells which are explosive emission sites each emitting a portion of electrons termed an ecton. The cathode spot processes are cyclic in nature due to the finiteness of the ecton lifetime. It is shown that an arc is self-sustained due to the explosive emission processes initiated on the interaction of the cathode plasma either with nonmetal inclusions present in the cathode surface (first-type spots) or with liquid metal jets ejected from the zone of an active cathode spot (second-type spots). Attention is focused on the physical processes occurring during the operation of a cathode spot cell. A statistical model of a vacuum arc is used to interpret the effect of the spontaneous extinction of an arc. It is shown that an increase in the arc current is accompanied by a slight increase in the number of simultaneously operating ectons; therefore, as observed in the experiments, the parameters of a vacuum do not greatly depend on the current up to the kiloampere level.
105 citations
"3-D Hydrodynamic Model of Metal Dro..." refers background in this paper
...It was found that the most probable diameter of an elemental molten metal crater on copper cathode is 4~5μm [14, 18]....
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...Many experimental studies were carried out to measure the parameters of vacuum arc tracks and micro-craters, which can provide some experimental data to complete the numerical modeling works [14]....
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16 Sep 1996
TL;DR: In this paper, a review of material transfer due to arcing based on published work by the authors and by the other investigators is presented, including a survey of contact materials, circuit parameters, electrode temperatures, and surrounding gases which have been determined to affect arc behavior and material transfer; the effect of contact surface temperature distribution, arc spot dimension, arc root stability, and arc duration on wearout or loss of contact material from two contacts; and an idea of balance transfer ("zero" loss) operation.
Abstract: One of the serious problems of arcing in relays and switches is leading to material transfer, thus resulting in the loss of contact material and the early end of lifetime. Although this phenomenon has been studied for many years, there are still many unsolved problems. This paper is a review of material transfer due to arcing based on published work by the authors and by the other investigators. Included are a discussion of transfer mechanism, called PSD model (particle sputtering and deposition model); a survey of contact materials, circuit parameters, electrode temperatures, and surrounding gases which have been determined to affect arc behavior and material transfer; the effect of contact surface temperature distribution, arc spot dimension, arc root stability, and arc duration on wearout or loss of contact material from two contacts; and an idea of balance transfer ("zero" loss) operation. It is expected that this paper could supply some basic considerations for controlling material transfer in practical applications.
83 citations
"3-D Hydrodynamic Model of Metal Dro..." refers background in this paper
...There is an intensive literature considering the material transfer and arc erosion [7]....
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TL;DR: In this paper, a simplified model based on magnetohydrodynamics theory is built and four cases with the arc chambers of different widths are calculated. And the influence of arc chamber width on the arc stagnation is preliminarily discussed according to the experimental results.
Abstract: In this paper, the complicated arc phenomena in air dc circuit breakers that are widely used in rail transit and vessels are investigated with both experimental and numerical approaches. Initially, the basic arc motion characteristics in the switch are presented by the recorded waveforms and images in the carefully designed breaking experiments. Phenomena of arc stagnation and back commutation are revealed and the influence of arc chamber width on the arc stagnation is preliminarily discussed according to the experimental results. Then, to make the nature of arc motion clear and to determine the influence details of the arc chamber width on arc motion characteristics, a simplified model based on magnetohydrodynamics theory is built and four cases with the arc chambers of different widths are calculated. The simulated arc behavior is presented by the temperature distribution sequences. In addition, the formation process of back commutation is described in detail by the variation of arc column. The influence mechanism of arc chamber width on arc motion is analyzed according to the differences of pressure propagation and temperature distribution in the arc chamber. Furthermore, the calculated arc displacement curves show that the arc stagnation time could be shortened and the risk of back commutation could be reduced by decreasing the arc chamber width within the reasonable extent.
65 citations
"3-D Hydrodynamic Model of Metal Dro..." refers background in this paper
...Electric arc is commonly known as a kind of thermal plasma with thousand Kelvin [4, 5], which could cause contacts material erosion and welding [6]....
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TL;DR: In this paper, a 2D axially symmetric hydrodynamic model was developed to describe the formation of a crater and liquid-metal jets on a vacuum arc cathode using Navier-Stokes equations for an incompressible viscous fluid with a free surface and a heat conduction equation taking convective heat transfer into account.
Abstract: 2-D axially symmetric hydrodynamic model has been developed to describe the formation of a crater and liquid-metal jets on a vacuum arc cathode using Navier–Stokes equations for an incompressible viscous fluid with a free surface and a heat conduction equation taking convective heat transfer into account. The formation of an elemental crater on a copper cathode during the operation of a cathode spot cell has been numerically simulated by varying the heat flux and the pressure produced by the cathode spot plasma. Based on the simulation results, we can distinguish three different modes of the crater formation process: 1) no splashing; 2) inertial splashing; and 3) active splashing. It has been shown that a crater with metal jets forced away can be formed within 30 ns of plasma action if the heat flux density is above $10^{12}$ W/ $\text{m}^{2}$ and the pressure is above $10^{8}$ Pa.
61 citations
"3-D Hydrodynamic Model of Metal Dro..." refers background or methods in this paper
...Thereafter the axial symmetry is destroyed due to the Rayleigh-Plateau instability developing in the edge of the metal liquid rim [9]....
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...[9], which the maximum velocity was 200m/s and the rang of angle was 20◦~ 25◦....
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...The control equations are shown in following [9, 15, 16]....
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...Mesyats developed a 2D axially symmetric hydrodynamic model to describe the formation of a microcrater in the cathode spot of a vacuum arc, which consist of Navier-Stokes equations and heat conduction equation [9]....
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