Abstract

This research set out to deliver a method of air flow redistribution to demonstrate a balanced rotor and stator predicted temperature of a mid range rotating electrical machine to within 2.5% with a maintained original efficiency and the temperature prediction should be proven based on air flow characteristics predicted via CFD and specified within MotorCAD. To achieve this a methodology of using an experimental rig to validate numerical baseline predictions was used and the validated model was used to investigate flow in different scenarios. The results from the study show that controlling and improving the direction and smoothness of the air at the inlet region of the fan can have a number of significant advantages to the flow split seen in the machine and also the power requirements of the fan. Importantly, it is shown that the excess flow through the barrel has an impact on the rotor flow due to the strength of the air jet coming from the barrel blocking the air through the rotor at the fan inlet region. The study concludes that by air flow improvements alone a predicted temperature balance of 3.7% between rotor and stator can be achieved with the recommended flow improvements, with an improvement in machine efficiency of 0.047% shown.