Abstract: A gas turbine engine is disclosed including a bifurcation fairing located in a bypass duct of the gas turbine engine and traversing the radial extent of the bypass duct. The bifurcation fairing has a delivery conduit inlet leading to a delivery conduit extending inside the bifurcation fairing, the delivery conduit being arranged in use for delivery of bypass air to one or more components of the gas turbine engine. A diverter conduit has a diverter conduit inlet from the delivery conduit upstream of the delivery conduit reaching the one or more components of the gas turbine engine. The diverter conduit has an outlet to a location other than the one or more components of the gas turbine engine.

Abstract: A nacelle for a turbofan gas turbine engine is provided. An inner wall of the nacelle defines an air intake which directs air into the fan section of the engine. The intake has, in flow series, an intake lip, a throat and a diffuser. The diffuser has, in flow series, first and second flow conditioning sections over both of which the flow cross-sectional area of the diffuser increases with increasing downstream distance from the throat. In addition, over the second section the nacelle inner wall lies substantially on a surface of an oblique circular cone having an apex which is offset from the centerline of the engine.

Abstract: A gas turbine engine including an outlet guide vane and a bifurcation fairing is disclosed. The outlet guide vane is located in a bypass duct of the gas turbine engine downstream of a fan and is of aerofoil form. The bifurcation fairing traverses the radial extent of the bypass duct and has an upstream end that blends into a trailing edge of the outlet guide vane. The bifurcation fairing includes a scoop protruding outwards from its side corresponding to a pressure side of the upstream outlet guide vane. The scoop includes a forward facing inlet leading to a delivery conduit extending inside the bifurcation fairing for delivery in use of bypass air to one or more components of the gas turbine engine.

Abstract: An initial geometry for a nacelle provides an intake at the upstream end of the nacelle and an exhaust at the downstream end of the nacelle. The intake has in flow series, an intake lip and a diffuser. The intake lip has a highlight defining the boundary between the inner and outer surfaces of the intake lip. On all longitudinal sections containing the axis of the engine (i) the inner and outer surfaces are tangency matched at the highlight, and (ii) the inner and outer surfaces have their maximum curvatures at the highlight.

Abstract: A nacelle for a turbofan gas turbine engine is provided. An inner wall of the nacelle defines an air intake which directs air into the fan section of the engine. The intake has, in flow series, an intake lip, a throat and a diffuser. The diffuser has, in flow series, first and second flow conditioning sections over both of which the flow cross-sectional area of the diffuser increases with increasing downstream distance from the throat. In addition, over the second section the nacelle inner wall lies substantially on a surface of an oblique circular cone having an apex which is offset from the centreline of the engine.

Abstract: A gas turbine engine is disclosed including a bifurcation fairing located in a bypass duct of the gas turbine engine and traversing the radial extent of the bypass duct. The bifurcation fairing has a delivery conduit inlet leading to a delivery conduit extending inside the bifurcation fairing, the delivery conduit being arranged in use for delivery of bypass air to one or more components of the gas turbine engine. A diverter conduit has a diverter conduit inlet from the delivery conduit upstream of the delivery conduit reaching the one or more components of the gas turbine engine. The diverter conduit has an outlet to a location other than the one or more components of the gas turbine engine.

Abstract: A gas turbine engine including an outlet guide vane and a bifurcation fairing is disclosed. The outlet guide vane is located in a bypass duct of the gas turbine engine downstream of a fan and is of aerofoil form. The bifurcation fairing traverses the radial extent of the bypass duct and has an upstream end that blends into a trailing edge of the outlet guide vane. The bifurcation fairing includes a scoop protruding outwards from its side corresponding to a pressure side of the upstream outlet guide vane. The scoop includes a forward facing inlet leading to a delivery conduit extending inside the bifurcation fairing for delivery in use of bypass air to one or more components of the gas turbine engine.

Abstract: A method of designing a nacelle for a gas turbine engine includes defining an initial geometry for the nacelle, pivoting, at each of one or more positions on a highlight and in a plane of a respective longitudinal section, a front portion of a section of an intake lip lying in the respective longitudinal section about the highlight, and obtaining an altered geometry for the nacelle by adjusting surfaces of the intake neighboring the pivoted front portion to smoothly blend the surfaces of the pivoted front portion to unadjusted surfaces of the intake further removed from the pivoted front portion.

Abstract: 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.

Abstract: An initial geometry for a nacelle provides an intake at the upstream end of the nacelle and an exhaust at the downstream end of the nacelle. The intake has, in flow series/an intake lip and a diffuser. The intake lip has a highlight defining the boundary between the inner and outer surfaces of the intake lip. On all longitudinal sections containing the axis of the engine (i) the inner and outer surfaces are tangency matched at the highlight, and (ii) the inner and outer surfaces have their maximum curvatures at the highlight.

Abstract: An initial geometry for a nacelle provides an intake at the upstream end of the nacelle and an exhaust at the downstream end of the nacelle. The intake has in flow series, an intake lip and a diffuser. The intake lip has a highlight defining the boundary between the inner and outer surfaces of the intake lip. On all longitudinal sections containing the axis of the engine (i) the inner and outer surfaces are tangency matched at the highlight, and (ii) the inner and outer surfaces have their maximum curvatures at the highlight.

Abstract: 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.