A quasi-analytical prediction method for gear load-independent power losses for shroud approaching

Abstract

To limit the adverse effect of the fluid pressure field in high-speed gearing systems, especially for the main reducer of helicopters, shrouds usually adopted to enclose and approaches the high-speed gears will play a vital role in the windage and pumping power losses in axial and radial directions. To better explore and predict the total load-independent losses, this paper proposes an improved quasi-analytical method to quantify the power losses caused by the windage and pumping effects, considering the gear pump characteristics with the compressibility of the air or air-oil mixture. The theoretical calculations using the improved model are then compared with experimental results in the open literature. Leveraging the swept volume of the gear pump, the squeezing/pocketing behavior of the fluids in the tooth space can get a better understanding as the shroud approaches the gear pair.