Experimental Investigation of Windage Loss Impacts on Electrical Machine with Oil Jet Cooling

Oil-jet cooling is reported to be particularly effective for electrical machines, where oil is directly sprayed onto critical components, such as the stator or rotor. However, windage losses within the air gap can be substantial and can significantly affect the machine's temperatures and overall efficiency, especially when oil mist or droplets penetrate the space between the stator and rotor. Quantifying windage losses is challenging due to the uncertainties in oil distribution within the end space and air gap. This paper explores windage losses analytically, numerically and experimentally at various rotational speeds. The impacts of surface roughness, fluid medium types, as well as speeds on the windage losses are shown. Future works on the impacts of other parameters on the windage loss are proposed.