Using a Semi-Staging approach to Improve Oil Scoop Capture Efficiency

Abstract

Spatial and weight restrictions on very high performance aeroengines require more advanced and efficient lubrication systems. An oil scoop is a device that aims to capture a jet of oil to feed high-speed bearings by directing the oil jet along the axial direction of the shaft via under-race feed to the bearing elements. Splashing is a prominent oil-morphology feature in oil scoop dynamics. Splashing happens after the oil jet impacts on the rotating oil scoop blades resulting in a centrifugally outward loss of oil. These loses contribute oil capture inefficiencies. There are optimisation approaches with the aim of limiting blades’ leading and trailing edge interaction with the oil jet in open literature. There are none, however, that has attempted to recapture the centrifugal losses to form part of the bearing feed, potentially needed to improve the overall oil capture efficiency. This, however, creates an additional challenge of driving the lubricants against centrifugal and gravitational forces towards a set of "bearing scoops" in stage 3. In this work, we attempted to capture the lubricants against these forces with vanes and results show a chance to achieve lubrication almost before the first shaft revolution. 2D CFD simulation shows a very good potential with this staging approach to improve scoop overall capture efficiency