Determination of the Velocity Field for the Calculation of Wall Heat Transfer Coefficients

Thermal calculation of electrical machines by the method of the lumped parameter thermal network is inextricably linked with empirically adjusted variables. The key to the accurate design thus lies in the ability to accurately determine these important variables, where the most important one is the wall heat transfer coefficient h (WHTC). The whole thermal design is a multiphysical problem in which it is necessary to calculate both the temperature and velocity fields and their mutual influence. This paper deals with the refinement of the determination of the velocity field in the area of the free shaft in order to create a theoretical basis for the determination of the velocity field in critical parts of the electrical machine. Since the article is focused on applications in electrical machines, the sensitivity analysis of a fully enclosed IPMSM motor by the DOE method is performed first. All calculations are performed by the CFD method in the ANSYS Fluent solver.