US Patent 8418953 Gas turbine engine nacelle

A nacelle for a gas turbine engine has an intake at the upstream end of the nacelle and an exhaust at the downstream end of the nacelle. The intake has, an intake lip and a diffuser. The diffuser has a main diffuser section and an optional shorter straight wall diffuser section. The main diffuser section is bounded by an inner wall of the nacelle, the inner wall curving in the airflow direction of the engine. On each longitudinal section containing the engine axis, at the downstream end of the main diffuser section the inner wall has a non zero curvature. Thus each circumferential position on the inner wall at the downstream end of the main diffuser section has a curvature defined by a respective radius of curvature. However, one or more of the radii of curvature differ from the others of the radii of curvature.