A boundary element method for eddy current problems having rotational symmetry

This thesis exploits the use of a boundary element technique for the analysis of linear induction devices with rotational symmetry. The electromagnetic fields and the power induced in a conducting medium (magnetic or non-magnetic) due to time harmonic either axial or transverse magnetic fields are calculated.;The boundary integral equations for this problem are first formulated in the general 3D form and then reduced to the rotating field and axial magnetic field (2D) cases. The boundary integral equations for both the rotating field and axial magnetic field cases are in the form of one-dimensional Fredholm integral equations of the second kind. The boundary integral equations (BIE's) are presented in two different forms; either combined (using Muller concept) or separate (direct formulation).;For small values of the electromagnetic penetration depth, where the BIE's formulation fails to converge to the correct numerical solution, the application of the impedance boundary condition (IBC) approximation is applied for both the rotating field and 2D cases. A comparison between the three different formulations; (a) the combined BIE's (b) the separate BIE's, and (c) the external IBC approximation is presented. The advantages and drawbacks of each formulation are discussed.;A brief survey of numerical methods which may be used to approximate the integral equations formulation is presented. Methods for treatment of the different order of singularities are reviewed and the application of first and quadratic element is considered. The effect of approximating sharp edges on the accuracy of the numerical solution is discussed and a numerical example is presented.;A general algorithm for both the rotating field and 2D cases is written and the accuracy of the numerical solution obtained is tested by comparing the numerical results with an analytical solution and available experimental values. Comprehensive numerical results are presented for the field distributions on the boundary and the normalized power induced versus R;The application of the multi-body case is presented. For the 2D case, the algorithm considered is used to solve an interesting practical problem, namely the calculation of the electromagnetic pressure distribution produced by an electromagnetic mold coaxial with a short shielded coil. (Abstract shortened with permission of author.)...