|
چکیده
|
Induction heating is a multi-physical process governed by coupled electromagnetic fields and heat transfer, with performance strongly dependent on coil configuration and process parameters. This study presents a comparative numerical analysis of internal and external induction heating of a stainless-steel cylindrical shell. A two-dimensional axisymmetric electromagnetic model based on Maxwell’s equations and the magnetic vector potential is developed under harmonic steady-state conditions. The coupled equations are solved to evaluate the magnetic stream function, induced eddy current density, and volumetric heat generation. The in-phase and out-of-phase components of the magnetic stream function, induced currents, and generated heat are analyzed for both heating configurations under identical operating conditions, including excitation frequency, applied current, coil geometry, and coil-to-workpiece distance. Results demonstrate that internal and external heating produce fundamentally different electromagnetic fields and heating patterns. Internal heating yields higher peak heat generation with hot spots on the inner surface, while external heating concentrates maximum heating on the outer surface. Edge and skin effects lead to localized heating at the upper and lower edges of the workpiece. Although internal heating generates more heat within the workpiece, it also increases coil losses, resulting in slightly lower overall efficiency than external heating. In both cases, the induced current density across the workpiece thickness follows a damped wave-shaped distribution rather than a classical exponential decay. These findings suggest that selecting internal or external induction heating should be based on the desired heating location, thermal uniformity, and process efficiency.
|