Gas turbine engine having a nacelle and a breather duct
Breather air, containing oil mist, is discharged from a nacelle 4 of a gas turbine engine through an exhaust port 26 at a surface 22 of the nacelle 4 . Energized air, at relatively high velocity is discharged from a clean air outlet 28 , and forms a barrier between the breather air and the external surface 22 , so preventing contamination of the surface 22 by oil deposited from the breather air.
1. A gas turbine engine comprising a nacelle and a breather duct providing communication between a component of the engine within the nacelle and the exterior of the nacelle, the breather duct opening at the exterior of the nacelle at a circular exhaust port, and a clean air outlet being disposed adjacent the exhaust port, the clean air outlet comprising an annular slot concentric with the exhaust port, to provide, in use, a barrier of clean air between the external surface of the nacelle and a flow of breather air from the exhaust port.
2. A gas turbine engine as claimed in claim 1 , in which the component is an oil lubricated component.
3. A gas turbine engine as claimed in claim 2 , in which the component is a gearbox.
4. A gas turbine engine as claimed in claim 1 , in which the clean air outlet is disposed at least partially downstream of the exhaust port.
5. A gas turbine engine as claimed in claim 1 , in which the clean air outlet comprises a porous skin providing the external surface of the nacelle in the region of the exhaust port.
6. A gas turbine engine as claimed in claim 1 , in which the clean air outlet is configured to direct clean air in a downstream direction.
7. A gas turbine engine as claimed in claim 1 , in which the exhaust port and the clean air outlet are provided on a mast which projects outwardly of the nacelle.
8. A gas turbine engine as claimed in claim 1 , in which, in normal operation of the engine, the flow rate of air from the clean air outlet is greater than the flow rate of air from the exhaust port.
9. A gas turbine engine as claimed in claim 1 , in which the clean air is supplied to the clean air outlet from a bypass duct of the engine.
10. A gas turbine engine as claimed in claim 5 , in which the clean air is supplied from the bypass duct through a fire zone of the engine.