Factors Affecting the Behaviour and Efficiency of a Targeted Jet Delivering Oil to a Bearing Lubrication System

Abstract

In this study oil delivery to an aero-engine bearing via a targeted jet was investigated using a bearing chamber test rig. The rig contains a high-speed rotating shaft of engine representative geometry within a stationary Perspex housing. Oil is collected from feedholes leading from scoops (scallops) on the shaft. The efficiency of this oil delivery system is dependent on jet structure and trajectory as it interacts with the rotating chamber flow. Flow visualization techniques and parametric tests are used to assess the influence of shaft speed and jet flowrate on oil collected through the feedholes. Detailed pictures of the structure of the jet in quiescent air are presented and compared with those from the rig, where there is a gas crossflow. As expected, jet break-up is accentuated in the rig. This influences jet impact behaviour at the scallop, and a consequent variation of oil distribution in the system is observed.