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Article
Publication date: 8 May 2009

Igor O. Golosnoy and Jan K. Sykulski

The purpose of this paper is to access performance of existing computational techniques to model strongly non‐linear coupled thermo‐electric problems.

266

Abstract

Purpose

The purpose of this paper is to access performance of existing computational techniques to model strongly non‐linear coupled thermo‐electric problems.

Design/methodology/approach

A thermistor is studied as an example of a strongly non‐linear diffusion problem. The temperature field and the current flow in the device are mutually coupled via ohmic heating and very rapid variations of electric conductivity with temperature and applied electric field, which makes the problem an ideal test case for the computational techniques. The finite volume fully coupled and fractional steps (splitting) approaches on a fixed computational grid are compared with a fully coupled front‐fixing method. The algorithms' input parameters are verified by comparison with published experiments.

Findings

It was found that fully coupled methods are more effective for non‐linear diffusion problems. The front fixing provides additional improvements in terms of accuracy and computational cost.

Originality/value

This paper for the first time compares in detail advantages and implementation complications of each method being applied to the coupled thermo‐electric problems. Particular attention is paid to conservation properties of the algorithms and accurate solutions in the transition region with rapid changes in material properties.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 28 no. 3
Type: Research Article
ISSN: 0332-1649

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Article
Publication date: 10 May 2011

Richard D. Chippendale, Igor O. Golosnoy, Paul L. Lewin and Jan K. Sykulski

The purpose of this paper is to investigate and explain the unexpected current flow patterns and twisting equipotential surfaces observed in strongly anisotropic materials.

227

Abstract

Purpose

The purpose of this paper is to investigate and explain the unexpected current flow patterns and twisting equipotential surfaces observed in strongly anisotropic materials.

Design/methodology/approach

Potential distributions and current flow paths in highly anisotropic composite materials were studied via numerical simulation and experimentally. Simplified composite panels with two plyes were analysed using a finite‐element model; the predictions were then confirmed experimentally.

Findings

The unexpected twisting equipotential surfaces and current flow patterns were found to be consistent with minimising of Joule heat release in the material. Numerical modelling suggests that the twisted profiles of the potential are highly sensitive to the anisotropic electrical conductivity.

Originality/value

This paper discusses the reverse current flows witnessed in a two‐layer anisotropic system. Such behaviour has never been predicted or observed experimentally before. The reported results will be of interest to anyone who is considering using anisotropic materials such as carbon fibre composites which might experience applied potential difference, such as lightning strikes.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 30 no. 3
Type: Research Article
ISSN: 0332-1649

Keywords

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Article
Publication date: 9 August 2018

Dongkyu Shin, Igor Golosnoy and John McBride

The purpose of this paper is to investigate a reliable evaluator of arc re-ignition and to develop a numerical tool for accurate prediction of arc behaviour of low-voltage…

109

Abstract

Purpose

The purpose of this paper is to investigate a reliable evaluator of arc re-ignition and to develop a numerical tool for accurate prediction of arc behaviour of low-voltage switching devices (LVSDs) prior to empirical laboratory testing of real products.

Design/methodology/approach

Two types of interruption tests have been carried out in the investigation of re-ignition evaluators. Arc modelling tool coupled with the load circuit has been developed to predict arc characteristics based on conventional magnetohydrodynamics theory, with special attention given to Lorentz force acting on the arc column and surface phenomena on the splitter plate. The model assumptions have been validated by experimental observation of arc motion and current and voltage waveforms.

Findings

It is found that the exit-voltage across the switching device and the ratio of system to exit-voltage at the current zero point are reliable evaluators for prediction of re-ignition. Where the voltage ratio is positive, instantaneous re-ignition does not occur. Further, the probability of re-ignition is very low if the voltage ratio is in the rage of −1.3 to 0.

Originality/value

It is observed that the voltage ratio can be considered as a reliable global evaluator of re-ignition, which can be used for various types of LVSD test conditions. In addition, it is shown that arc modelling allows a good prediction of the current and voltage waveforms, arc motion as well as the exit-voltage, which can be used to obtain the evaluator of re-ignition.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 37 no. 6
Type: Research Article
ISSN: 0332-1649

Keywords

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