Radiative energy balance in cylindrical nitrogen arcs

Hermann, W.; Schade, E.

doi:10.1016/0022-4073(72)90183-5

Cited by 44 publications

(14 citation statements)

References 16 publications

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“…The grey body model is of simplified NEC model used by Villa et al 26 . Although this approach simplifies the underlying model for solving the RTE, by neglecting spectral and geometric dependencies, it does add complexity in the techniques for solving equation (6); this process can be broken down into three steps. In the first, the plasma is assumed to absorb energy from its surroundings which are at an ambient temperature, T 0 .…”

Section: B Grey Body Modelmentioning

confidence: 99%

“…A full description of the radiative losses within a plasma arc requires solving for energy balance at every point in the arc, spanning the full range of wavelengths in the electromagnetic radiation. These radiative effects are described in full by the radiative transfer equation (RTE) and this has been solved fully for stationary cylindrically symmetric lightning arcs by Lowke 4 , Lowke and Capriotti 5 and Hermann and Schade 6 . However for dynamic simulations, the exact solution of the RTE is prohibitively slow and numerical simplifications have been sought 7 .…”

Section: Introductionmentioning

confidence: 99%

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Equation of state driven radiative models for simulation of lightning strikes

Apsley,

Millmore,

Nikiforakis

2021

Preprint

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This work is concerned with the numerical simulation of plasma arc interaction with aerospace substrates under conditions akin to lightning strike and in particular with the accurate calculation of radiative heat losses. These are important because they have a direct effect on the calculation of thermal and pressure loads on the substrates, which can lead to material damage under certain conditions. Direct numerical solution of the radiation transport equation (RTE) in mesoscale simulations is not viable due to its computational cost, so for practical applications reduced models are usually employed. To this end, four approximations for solving the RTE are considered in this work, ranging from a simple local thermodynamical behaviour consideration, to a more complex spectral absorption dependent on the arc geometry. Their performance is initially tested on a one-dimensional cylindrical arc, before implementing them in a multi-dimensional magnetohydrodynamics code. Results indicate that inclusion of spectral absorption is necessary in order to obtain consistent results. However, the approaches accounting for the arc geometry require repeated solution of the computationally intensive Helmholtz equations, making them prohibitive for multi-dimensional simulations. As an alternative, a method using the net emission coefficient is employed, which provides a balance between computational efficiency and accuracy, as shown by comparisons against experimental measurements for a plasma arc attaching to an aluminium substrate.

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Section: B Grey Body Modelmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Equation of state driven radiative models for simulation of lightning strikes

Apsley,

Millmore,

Nikiforakis

2021

Preprint

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“…Moreover, the model is computationally cheap, which is very important if the method is used for development purpose and large parameter studies. The choice of net-emission coefficient is taken from [20,27]. There is a large temperature difference between the arc (∼ 20000 K) and the surrounding cold gas (∼ 2000 K).…”

Section: Modelmentioning

confidence: 99%

Application of High Current and Current Zero Simulations of High‐Voltage Circuit Breakers

Franck

Seeger

2006

Contrib. Plasma Phys.

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This paper reports on the use of computational fluid dynamic (CFD) simulations to predict the interruption behaviour of high-voltage circuit breakers (HV-CB) using the self-blast principle. Two different levels of accuracy of the arc model are proven to be sufficiently accurate for simulating the high-current phase and the period around current zero (CZ). For the high-current phase, a simplified equivalent model of the arc is implemented to predict the pressure build-up, and even more important to accurately trace the hot gas from the arcing zone into the exhausts and the heating volume. A detailed analysis of the gas mixing in the heating volume for different arcing times and current amplitudes showed the optimum geometrical design of the heating volume. For the CZ phase, a more detailed arc model is needed including the effects of ohmic heating, radiative energy transfer, and turbulent cooling fully resolved in space and time. The validation with experiments was done and shows good agreement which justifies the use of the implemented model. With it, scaling laws varying only one parameter at a time (pressure and applied current slope) were derived and confirm previously found empirical laws. This is of particular interest, as it is very difficult to derive such scaling laws from experiments where the scatter is always very large and where it is impossible to vary only one parameter at a time. The influence of the most important geometrical parameters of the nozzle on the interruption performance is shown. In addition to previous experimental indications of this, the simulation reveals that turbulent cooling on the arc edge is the main reason for the difference in interruption performance. Moreover, the exact spatio-temporal build-up of arc resistance and with it the detailed understanding of the arc interruption process is possible and shown here for the first time. These simulations enable us to predict HV-CB performance and to minimise the number of development tests and are routinely used in new development projects.

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“…Radiation losses were calculated according to the theoretical work of Hermann [11]. The electrical conductivity is found from (24) where electron density, and cross section of the electron-plasma component collosions, with a maximum value of S/m.…”

Section: Computational Aspectsmentioning

confidence: 99%

The gas dynamics of current-limiting devices during immobility time

Merck

Zatelepin²

1997

IEEE Trans. Plasma Sci.

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Abstract-The aim of this paper is to extend our knowledge about the gas-dynamic processes in arcs during immobility time. For this purpose, the conservation equations in magnetohydrodynamic approximation were coupled with the thermochemical and Maxwell equations. Special features are the introduction of dissociation and ionization of nitrogen and oxygen, and the simultaneous calculation of the distributions of current density and magnetic induction in the arc. Numerical calculations were performed with a reduced two-dimensional (2-D) time-dependent model. Results of the calculations were compared with measurements. The development in time of the measured and calculated arc voltage and arc chamber pressure show very good agreement. The pumping effect of the double vortex in the arc region was confirmed by optical measurements. It is concluded that the three-layer model is a good representation for the main physical features during the immobility time, and that the presence of highly conducting gas in the downstream region of the arc is essential for its downstream movement.

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Radiative energy balance in cylindrical nitrogen arcs

Cited by 44 publications

References 16 publications

Equation of state driven radiative models for simulation of lightning strikes

Equation of state driven radiative models for simulation of lightning strikes

Application of High Current and Current Zero Simulations of High‐Voltage Circuit Breakers

The gas dynamics of current-limiting devices during immobility time

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