On windage power loss reduction achieved by flanges

It is commonly accepted that the load-independent losses in high-speed gears can become prominent for peripheral speeds above 100 m/s. In this context, it has been shown that flanges and shrouds can mitigate these windage effects but no clear conclusions have been reached about the influence of radial and axial obstacles, especially for high-speeds. Moreover, the proposed solutions should be compatible with the casing design, including the possibility to properly lubricate and cool down the gears. In this paper, a specific test rig is used in order to investigate the power loss reductions when either one or two axial flanges are mounted close to the gears. It is shown that windage power losses are strongly reduced when flanges are very close to the gear faces. The influence of several parameters such as the number of flanges, the gear module and the gear geometry (i.e. spur or helical) is discussed. Finally, an approximate equation is proposed, which can be used to estimate WPL reductions at the design stage.