Technologies are described herein for a drag recovery scheme using a boundary layer bypass duct system. In some examples, boundary layer air is routed around the intake of one or more of the engines and reintroduced aft of the engine fan in the nozzle duct in a mixer-ejector scheme. Mixer-ejectors mix the boundary layer flow to increase mass flow.

A turbine arrangement for a bi-directional reversing flow is provided. The turbine arrangement may include a rotor rotatably mounted to rotate about an axis of the turbine arrangement, and the rotor may have a plurality of rotor blades disposed circumferentially thereabout. A first set of guide vanes may be circumferentially disposed about the axis for directing the bi-directional reversing flow to and from the rotor blades via a first flow passaged defined by a first duct. A second set of guide vanes may be axially spaced from the first set of guide vanes and circumferentially disposed about the axis for directing the bi-directional reversing flow to and from the rotor blades via a second flow passage defined by a second duct. The guide vanes may be disposed at a greater radius than the rotor blades, such that the guide vanes are radially offset from the rotor blades.

A compressor rotor airfoil in a gas turbine engine is presented. Opposed pressure and suction sides are joined together at chordally opposite leading and trailing edges. The pressure and suction sides extend in a span direction from a root to a tip. A leading edge dihedral angle is defined at a point on the leading edge between a tangent to the airfoil and a vertical. The leading edge dihedral angle has a span-wise distribution. The distribution has at least one inflection point. A method of reducing a rub angle between a compressor rotor blade and a casing surrounding the blade is also presented.

Air inlet duct of a turbine engine, in particular an aircraft turbine engine comprising a gas generator, which extends axially between the air inlet and the gas generator and has a first axial wall part and a second wall part which is angularly offset with respect to the first part, which duct is capable of causing, in a shedding region, shedding of the boundary layer formed by an air flow along the wall of the duct; and a device for controlling said shedding of the boundary layer, characterised in that the control device comprises an air-blowing pipe which opens via at least one air-injection opening which is directly upstream of the shedding region, the blowing pipe being connected to an air intake positioned upstream of said air-injection opening or in the shedding region and comprising an air compressor means between the air intake and the air-injection opening.

A multi-stage axial compressor with an inner wall including a step portion for each of the compressor stages. Each step portion is defined along a respective stage. Each step portion may extend over at least a majority of an axial length of the stage. Each step portion may optionally include a point aligned with a maximum thickness of the airfoil portions of the rotor blades and a point aligned with a maximum thickness of the stator vanes. Adjacent step portions are connected by a transition portion converging toward a central axis of the compressor from the upstream step to the downstream step. Each transition portion has a steeper slope than that of the adjacent step portions. A method of directing flow through a multi-stage axial flow compressor is also discussed.

A gas turbine system includes an exhaust processing system that may process exhaust gas generated by a gas turbine engine, the exhaust processing system includes an exhaust diffuser that may receive the exhaust gas from a turbine of the gas turbine engine and having an annular passage disposed between an inner annular wall and an outer annular wall, and an air injection assembly disposed within the exhaust diffuser. The air injection assembly includes one or more air injection conduits disposed within the annular passage of the exhaust diffuser and including fluid injection holes that may direct a cooling fluid into a first mixing region of the exhaust diffuser.

Technologies are described herein for a drag recovery scheme using a boundary layer bypass duct system. In some examples, boundary layer air is routed around the intake of one or more of the engines and reintroduced aft of the engine fan in the nozzle duct in a mixer-ejector scheme. Mixer-ejectors mix the boundary layer flow to increase mass flow.

To provide a stator vane of a fan or compressor that is reduced in loss by enlarging a laminar flow area over a blade surface. With the stator vane, provided that an angle formed by a tangent to the blade surface at a point and the axial direction of the turbofan engine, that is, a parameter that is a blade surface angle normalized is referred to as a normalized blade surface angle, an upper limit is set for the change rate in the chord direction of the normalized blade surface angle on the pressure surface, and an upper limit is set for the normalized blade surface angle at a predetermined location in the chord direction on the suction surface.

A boundary layer ingestion fan system for location aft of the fuselage of an aircraft is shown. It comprises a nacelle (501) defining a duct, and a fan located therewithin. The fan comprises a hub arranged to rotate around a rotational axis (A-A) and a plurality of blades attached thereto. Each blade has a span (r) from a root at the hub defining a 0 percent span position (r=0) to a tip defining a 100 percent span position (r=1) and a plurality of span positions therebetween (r ∈ [0, 1]), and leading and trailing edges defining, for each span position, a chord therebetween to having a chord length (c). For each of said plurality of blades, the ratio of chord length at the 0 percent span position (c.sub.hub) to chord length at the 100 percent span position (c.sub.tip) is 1 or greater.

An aerofoil assembly includes a platform and a plurality of aerofoils extending radially outward from the platform. The platform has a first edge, a second edge, and a platform surface disposed between the first edge and the second edge. Each aerofoil has a leading edge proximal to the first edge and a trailing edge distal to the first edge. A pitch spacing is defined between the leading edges of adjacent aerofoils along the platform surface. A mid-pitch location is defined midway along the pitch spacing. The platform defines one or more recesses disposed between the leading edges of the plurality of aerofoils and the first edge. Each of the one or more recesses is disposed proximal to the mid-pitch location between adjacent aerofoils.