Numerical study on the impact of end windings porosity on the fluid flow and heat transfer in a totally enclosed fan-cooled electrical machine

Computational fluid dynamics (CFD) was used to model the end region of a typical low voltage Totally Enclosed Fan-Cooled (TEFC)induction motor (output power 11 kW). The complexity of the end windings geometry provides a significant CFD modelling challenge; in previous works approximated and simplified geometries were usually employed to model the end windings to reduce the complexity of the model and because of computational limitations [1]-[3]. In this work a more realistic end windings geometry representation was used to in order to investigate in more detail the complex fluid flow and thermal phenomena occurring in the end region which typically is an area of most interest for thermal management. This paper describes the influence of the different level of end winding's porosity on the predictions of fluid flow and heat dissipation rate in the end region. An alternative cooling arrangement, consisting of shaft mounted stirrers, was also considered and a CFD investigation was carried out in order to assess the impact of the proposed internal cooling design on the fluid flow and thermal performance of the end region of the selected TEFC machine. The methodology developed for the end windings geometry for this specific machine design can be potentially applied to different kinds of electrical machines.