Modeling Engine Sump Flows

The high shaft speeds in modern airbreathing engines (typically 10-15,000 RPM) combined with the tight confines in engine sumps lead to significant challenges in draining oil from these passages. The windage from the vortical flow created by the shaft imparts significant energy to the droplets shed from bearings and seal runners. A computational tool is being created to address these issues. A seal runner analysis, based on a boundary layer solution of the thin film equations provides the characteristics of fluid shed from this device. A Lagrangian droplet tracking scheme has been developed to ascertain the momentum imparted to the film on the outer sump wall including droplet deformation/breakup in flight and a wall collision/secondary atomization module. The outer sump wall analysis includes mass/momentum addition from the droplets, shear stress imparted by the airflow and sump wall, and includes a model for the drain outflow as well. Rolls Royce Allison Engine Company and Mr. John Munson in the Mechanical Technology Department.

Current and former graduate students participating in this work include: Masayoshi Shimo, Vladi Weinstock,