An experimental and numerical study of airflow behaviour in a low-voltage concentric-wound machine

This paper discusses the potential thermal improvements in a low-voltage concentric-wound machine by modifying the airflow paths in the end-windings. Two machines were built and tested by means of heat runs. One machine had a non-uniform array of predominantly blocked end-winding gaps at both ends of the machine. The second machine had modifications to ensure fully unblocked end-winding gaps at both ends of the machine. The selective blocking of the gaps made it possible to evaluate the impact of each stator end-winding modification. CFD simulations of the complete set of design variants were carried out using the ANSYS CFD package. The introduction of end-winding gaps had a positive effect on both stator and rotor temperatures. The various changes in flow patterns observed from CFD were correlated to the test results to provide explanations of the cooling dynamics.