Using CFD to Improve Aero-Engine Air/Oil Separator Design

Within the transmission system of a commercial gas turbine engine the lubrication and cooling of shaft bearings is performed by oil injected into bearing chambers that are typically sealed with air-pressurised labyrinth seals. The subsequent air/oil mixture is scavenged from the bearing chamber with the oil being re-used, whilst the air is discharged overboard via an air/oil separator. Efficiency of separators is becoming a high priority to industry, with any loss of oil an environmental concern. To help improve the design of separators a computational model was created of an existing design and coupled two-phase CFD calculations were performed. A limited amount of experimental data, collected by particle image velocimetry (PIV) was available for validation.