Application of asymptotic expansions to model two-dimensional induction heating systems. Part I: calculation of electromagnetic field distribution

We analyze the effect of a radio-frequency alternating magnetic field generated in the vicinity of solid or liquid electrically conducting components, such as used in induction heating processes. The field can penetrate only into a thin magnetic skin located beneath the conductor surface, where the generated heat and stresses are concentrated. This most often leads to major numerical difficulties, especially for very thin magnetic skins. Therefore, we have developed a mathematical model of the electromagnetic field distribution inside the conductors for planar and axisymmetric configurations by using a matched asymptotic expansion technique. Among other features, our method takes the curvature of the conductor surfaces into account. A practical numerical implementation of our model is detailed here, and numerical calculations are carried out in order to extend the model to limiting cases such as curvature discontinuities and corners. These calculations compare successfully with complete numerical computations.