The capability to model an aeroengine internal gearbox in its entirety using CFD is currently hampered by the complexity of the two-phase, highly rotating system and the computational resource required. The University of Nottingham Technology Centre in Gas Turbine Transmission Systems has established modeling capability for an unmeshed, shrouded spiral bevel gear and has conducted a number of experimental investigations for such a gear operating within a cylindrical chamber [1, 2].
In this paper a CFD model is created of an external chamber geometry comparable to that on the experimental test rig using the commercial CFD code Fluent. Droplets are introduced into this chamber at a range of diameters and their trajectories tracked. Small droplets (0.1 μm to 1μm) are representative of mist within the chamber and essentially follow the highly rotating air flow. Droplets in the range 1 μm to 100 μm travel to the chamber walls but interact with the flow such that they may be in the core flow some time before impact. Larger droplets in the range 100 μm to 5000 μm are largely undeflected, travelling directly to the walls.
The Fluent thin film model is used to generate wall films from droplet impacts and the simulation shows how film is likely to be driven away from the gear by the air flows within the chamber forming a thicker film away from the gear axial location.
