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Novel approach to modeling of 3D coupled electroheat problems with time-varying geometries is presented. Instead of time-expensive remeshing of the whole system in every time step it is used the initial mesh that takes into account the expected geometric changes. In the course of computations, its relevant elements are able to adaptively change their shapes and material parameters. The methodology...
The increased application of HVDC components in electrical energy systems has led to new challenges in diagnostic testing and measurement of electrical insulation. In addition to other diagnostic methods Partial Discharge (PD) diagnosis at DC voltage is currently subject to much discussion worldwide. This is because the established and approved procedures, methods and evaluation techniques at AC voltages...
Composite materials are an integral part of electrical systems; however, the determination of their dielectric properties through calculation is sometimes problematic. The aim of this paper is to demonstrate a way to determine the effective permittivity of a composite material by using a 3D electric field model while exploiting the distribution of electric energy and to verify the results by values...
A 3D model of combined induction and laser cladding is presented. This electroheat process is characterized by time-varying geometry because of material added in the form of metal powder in order to form the clad. The paper brings a novel approach to its modeling which required expensive remeshing of the whole investigated domain in every time step. The offered technique is based on local adaptive...
Force and thermal effect in bus-bar systems are investigated. The goal of this research is to find the configuration exhibiting their minimum possible values. The computations are carried out numerically, using the fully adaptive higher-order finite element method. The methodology is illustrated with several examples whose results are discussed.
The paper deals with basic investigation of AC breakdown behaviour of gaseous insulation with synthetic air at different level of field homogeneity and gas pressure. The measurement was performed at different gas pressure ranging from 0.1 to 0.25 MPa and gap distances from 1 to 9 cm, using an electrode test-set “tip-bowl”. The test parameters were chosen in such a way that different field types could...
The shape of an inductor for pre-heating and/or post-heating metal parts is optimized with the aim to reach the prescribed pattern of temperature along the place to be consequently welded by laser beam. The task represents a nonlinear inverse multi-parametric problem that is solved for a given range of field current frequencies. While the direct part of the problem is solved by a fully adaptive higher-order...
Mathematical model of laser heating with induction pre- and/or post-heating is presented and solved. The purpose of this combined way of heat treatment is to reduce residual mechanical stresses in the surface layers of the processed material produced by high temperature gradients at the spots heated by the laser beam. The 3D model takes into account all important nonlinearities including the temperature...
A novel prospective way of continuous surface heating of steel work-pieces by a laser beam is modelled. The process is supplemented with pre-heating and post-heating of the heated parts by a classic inductor in order to avoid unacceptably high temperature gradients and subsequent mechanical stresses in the processed material. Its continuous mathematical model is solved numerically in 3D in the hard-coupled...
An electromagnetic actuator with nonlinear structural parts is modelled and optimized. The aim of the optimization is to obtain a flat static characteristic and reach the highest possible force acting on its plunger (manufactured of permanent magnet) at the smallest possible dimensions. The solution of the problem is carried out numerically by the professional software package COMSOL Multiphysics...
The influence of three-phase overhead power lines on parallel steel pipelines is investigated. The principal monitored value is their resistive heating. The computations are realized numerically, by the finite element method. The comparison of adaptive techniques in finite elements methods is shown using software Agros 2D and COMSOL Multiphysics. The methodology is illustrated by two examples whose...
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