Windage power loss reductions in high-speed gear pairs

This paper deals with recent experimental and numerical research in the possible reduction of windage power losses (WPL). It is accepted that these load-independent losses become prominent over other sources in mechanical transmissions with peripheral speeds above 100 m/s as is the case in energy production, aeronautics and electric vehicles. So far, the majority of the experiments and models deal with WPL evaluation for one single rotating pinion. The unique test rig designed at INSA Lyon makes it possible to measure both the WPL of a single pinion or a non-meshing pinion-gear pair. A number of comparisons between experimental and numerical results are presented and commented upon. It is shown, that the gear environment changes the airflow and, in depending on the cases, it can either reduce or increase WPL. Finally, the influence of pinion-gear couplings on WPL is discussed as well as the interest of shrouds and deflectors.