Numerical Study of Electric Motors Cooling Using an Axial Air Flow

Abstract

– A numerical study has been carried out considering the heat transfer inside a four-pole synchronous electric motor. The computational work has been carried out using the commercial package ANSYS-CFX 2021 R1. The focus of this study is on the effect of an axial air flow passing through the gap between the stator and the rotor. The rate of cooling of the axial flow in terms of the average Nusselt number has been investigated at different rotational speeds and air flows. All surfaces were considered smooth. The source of heat generation was considered only within the rotor from the electrical windage resistance while the stator was considered insulated. The effect of the rotational speed and axial flow has been represented by a rotational and an axial Reynolds number which were varied in the ranges of 1750- 27000 and 2140- 6425, respectively. The numerical results have been validated using published experimental data with an acceptable deviation. Results showed that the average Nusselt number increases with both the rotational and the axial Reynolds numbers. However, the axial Reynolds number has a more dominant effect on the rate of cooling than the rotational Reynolds number.