Abstract: A gas turbine engine has a quasi-non-dimensional mass flow rate in a defined range and a specific thrust in a defined range to achieve improved over all performance, taking into account fan operability and/or bird strike requirements as well as engine efficiency. The defined ranges of quasi-non-dimensional mass flow rate and specific thrust may be particularly beneficial for gas turbine engines in which the fan is driven by a turbine through a gearbox.

Abstract: A gas turbine engine has a cycle operability parameter ? in a defined range to achieve improved overall performance, taking into account fan operability and/or bird strike requirements as well as engine efficiency. The defined range of cycle operability parameter ? may be particularly beneficial for gas turbine engines in which the fan is driven by a turbine through a gearbox.

Abstract: A gas turbine engine comprising in flow series: a fan; a series of outlet guide vanes; and a bifurcation. The outlet guide vanes are more densely distributed in a region circumferentially aligned with the bifurcation than in a region circumferentially offset from the bifurcation.

Abstract: A gas turbine engine has a fan tip air angle and/or a fan blade tip air angle in a defined range to achieve improved over all performance, taking into account fan operability and/or bird strike requirements as well as engine efficiency. The defined ranges of fan tip air angle and/or a fan blade tip air angle may be particularly beneficial for gas turbine engines in which the fan is driven by a turbine through a gearbox.

Abstract: A gas turbine engine comprising a fan, a bypass duct positioned downstream of the fan and defined by an inner casing and an outer casing, a series of outlet guide vanes arranged downstream of the fan, the outlet guide vanes extending between the inner casing and the outer casing of the bypass duct; and a bifurcation positioned downstream of the outlet guide vanes and extending between the inner casing and the outer casing. The bifurcation comprises a leading edge, and the leading edge of the bifurcation is shaped so as to protrude axially forward by a varying distance from the inner casing to the outer casing so as to improve uniformity of a static pressure field formed, in use, immediately upstream of the bifurcation.

Abstract: A gas turbine engine 10 is provided in which a fan having fan blades 139 in which the camber distribution relative to covered passage of the fan 13 allows the gas turbine engine to operate with improved efficiency when compared with conventional engines, whilst retaining an acceptable flutter margin.

Abstract: A gas turbine engine 10 is provided in which a fan having fan blades 139 in which the camber distribution relative to covered passage of the fan 13 allows the gas turbine engine to operate with improved efficiency when compared with conventional engines, whilst retaining an acceptable flutter margin.

Abstract: A slot is provided in an endwall of a flow passage, for example between two stator vanes or rotor blades of a gas turbine engine. The length direction of the flow passage is aligned substantially with the main flow through the flow passage. The alignment of the slot means that the “over-turned” boundary layer flow can be extracted through the slot but with minimal impact on the mainstream flow.

Abstract: A gas turbine engine comprising in flow series: a fan; a series of outlet guide vanes; and a bifurcation. The outlet guide vanes are more densely distributed in a region circumferentially aligned with the bifurcation than in a region circumferentially offset from the bifurcation.

Abstract: A gas turbine engine comprising a fan, a bypass duct positioned downstream of the fan and defined by an inner casing and an outer casing, a series of outlet guide vanes arranged downstream of the fan, the outlet guide vanes extending between the inner casing and the outer casing of the bypass duct; and a bifurcation positioned downstream of the outlet guide vanes and extending between the inner casing and the outer casing. The bifurcation comprises a leading edge, and the leading edge of the bifurcation is shaped so as to protrude axially forward by a varying distance from the inner casing to the outer casing so as to improve uniformity of a static pressure field formed, in use, immediately upstream of the bifurcation.

Abstract: A rotor blade for a gas turbine engine, comprising an aerofoil having pressure and suction surfaces, leading and trailing edges, and an array of passages at a tip region of the aerofoil. The passages extend from the pressure surface to the suction surface of the aerofoil and are disposed so that the array creates, in operation, a planar jet of gas issuing from the suction surface. The jet is inclined outwardly from the suction surface and towards the tip, and in the direction from the leading edge to the trailing edge. The jet inhibits migration away from the suction surface of a clearance vortex formed by leakage of air over the tip of the rotor blade.

Abstract: A rotor blade for a gas turbine engine, comprising an aerofoil having pressure and suction surfaces, leading and trailing edges, and an array of passages at a tip region of the aerofoil. The passages extend from the pressure surface to the suction surface of the aerofoil and are disposed so that the array creates, in operation, a planar jet of gas issuing from the suction surface. The jet is inclined outwardly from the suction surface and towards the tip, and in the direction from the leading edge to the trailing edge. The jet inhibits migration away from the suction surface of a clearance vortex formed by leakage of air over the tip of the rotor blade.