CFD modelling of an entire synchronous generator for improved thermal management

This paper is the first in a series dedicated to investigating the airflow and thermal management of electrical machines. Due to the temperature dependent resistive losses in the machine´s windings any improvement in cooling provides a direct reduction in losses and an increase in efficiency. This paper focuses on the airflow which is intrinsically linked to the thermal behaviour of the machine as well as the windage power consumed to drive the air through the machine. A full CFD model has been used to analyse the airflow around all major components of the machine. Results have been experimentally validated and investigated. At synchronous speed the experimentally tested mass flow rate and torque were under predicted by 4% and 30% respectively by the CFD. A break-down of torque by component shows that the fan consumes approximately 87% of the windage torque.