Abstract: A gas turbine engine includes a core engine casing and a bypass duct defined between a nacelle and the core engine casing. The gas turbine engine further includes a plurality of diverter fences pivotally coupled to the core engine casing. Each diverter fence is pivotable relative to the core engine casing about a pivot axis, which is circumferentially and obliquely inclined with respect to a principal rotational axis. Each diverter fence is configured to move between a first position in which an outboard edge is disposed adjacent to a casing outer surface, and a second position in which the outboard edge is radially spaced apart from the casing outer surface, such that each diverter fence radially extends outwards from the casing outer surface into the bypass duct.

Abstract: A cabin blower for an aircraft, the system comprising: a cabin blower compressor; an electric machine; and a controller configured to control the cabin blower system so that: in a cabin blower mode of operation, the cabin blower compressor is driven by power extracted from one or more spools of a gas turbine engine of the aircraft and provides a flow of air to a cabin of the aircraft. The controller may be further configured to control the system so that: in a rotor bow mitigation mode of operation, the cabin blower compressor is driven by the electric machine using electrical power from an electrical power source and provides a flow of air through a core of the gas turbine engine to remove heat from the core. A method of operating a cabin blower system of an aircraft is also provided.

Abstract: A method of determining performance characteristics of a flow machine having a rotor interacting with a flow field. The method comprises: receiving performance data for the flow machine comprising data values of a performance parameter of the rotor and mass flow for the flow machine at one or more defined rotor condition, the performance data defining a two-dimensional array of data in which points for a common rotor condition are identifiable; determining or receiving exit mass flow values for the flow downstream of the rotor; and identifying one or more point in the received performance data and interpolating from said one or more point to a corresponding one or more point at a different rotor condition based on a correlation of the exit mass flow values for said points.

Abstract: A gas turbine engine includes a core engine casing, a bypass duct and a core engine duct. The gas turbine engine further includes a plurality of flaps pivotally coupled to the core engine casing and arranged circumferentially around a principal rotational axis. Each flap extends from a first casing end and is configured to pivotally rotate relative to core engine casing about a pivot axis between a first position and a second position. In the first position, each flap is disposed in a circumferential direction and is radially disposed between a plurality of outlet guide vanes and a plurality of stator vanes. In the second position, each flap is inclined to the first position and extends at least partially into the bypass duct and the core engine duct.

Abstract: A gas turbine engine includes a core engine casing, a bypass duct and a core engine duct. The gas turbine engine further includes a plurality of flaps pivotally coupled to the core engine casing and arranged circumferentially around a principal rotational axis. Each flap extends from a first casing end and is configured to pivotally rotate relative to core engine casing about a pivot axis between a first position and a second position. In the first position, each flap is disposed in a circumferential direction and is radially disposed between a plurality of outlet guide vanes and a plurality of stator vanes. In the second position, each flap is inclined to the first position and extends at least partially into the bypass duct and the core engine duct.

Abstract: A gas turbine engine includes a core engine casing and a bypass duct defined between a nacelle and the core engine casing. The gas turbine engine further includes a plurality of diverter fences pivotally coupled to the core engine casing. Each diverter fence is pivotable relative to the core engine casing about a pivot axis, which is circumferentially and obliquely inclined with respect to a principal rotational axis. Each diverter fence is configured to move between a first position in which an outboard edge is disposed adjacent to a casing outer surface, and a second position in which the outboard edge is radially spaced apart from the casing outer surface, such that each diverter fence radially extends outwards from the casing outer surface into the bypass duct.

Abstract: A ducted gas turbine engine comprising a fan and a guide vane downstream of the fan, wherein the fan is a Variable Pitch Fan (VPF) configured to operate in a first position for generating forward thrust and a second position for generating reverse thrust; wherein a duct wall positioned radially outside the Variable Pitch Fan comprises one or more vents extending through the duct wall, and wherein each vent is located forward of the guide vane.

Abstract: A VTOL aircraft has fixed wings and a rotor blade system for providing lift in active and passive modes thereof. Operation of the rotor blade system may be switched between the active mode in which the rotor blade system is driven by a power system of the aircraft and the passive mode in which the rotor blade system is not driven by the power system, the rotor blade system being configurable to provide lift in the passive mode during forward flight of the aircraft. The rotor blade system provides lift in the passive mode, allowing the fixed wings to be shorter than in the case where the rotor system provides lift during vertical take-off and landing but otherwise has no function, thus providing aircraft which is lighter, more compact and more efficient than similar aircraft of the prior art.

Abstract: A cabin blower for an aircraft, the system comprising: a cabin blower compressor; an electric machine; and a controller configured to control the cabin blower system so that: in a cabin blower mode of operation, the cabin blower compressor is driven by power extracted from one or more spools of a gas turbine engine of the aircraft and provides a flow of air to a cabin of the aircraft. The controller may be further configured to control the system so that: in a rotor bow mitigation mode of operation, the cabin blower compressor is driven by the electric machine using electrical power from an electrical power source and provides a flow of air through a core of the gas turbine engine to remove heat from the core. A method of operating a cabin blower system of an aircraft is also provided.

Abstract: A system for providing active flow control in an aircraft having a gas turbine engine. The system includes an environmental control system that includes a cabin blower system having a compressor operable to compress a fluid delivered by a fan section of the gas turbine engine to generate a pressurised fluid for use by the environmental control system. The environmental control system is fluidicly connected to an active flow control system via a fluid supply line, for allowing the pressurised fluid generated by the compressor to be supplied to the active flow control system so that it can be ejected from the aircraft across an exterior surface of a movable control element of the aircraft.

Abstract: A lift rotor arrangement (100) for a VTOL aircraft (200). The lift rotor arrangement (100) comprises: a fairing (6) mounted on a wing segment (10); and first and second rotor blades (17, 18) mounted on a first shaft (4) extending vertically from the fairing (6). The first shaft (4) is movable between an extended position in which the first and second rotor blades (17, 18) are vertically spaced above the wing segment (10) and are rotatable to provide vertical lift, and a retracted position in which the first and second rotor blades (17, 18) are rotationally-fixed with the first rotor blade (17) stowed within the wing segment (10). The blades (17, 18) may be rotatable around an axis substantially perpendicular to the axis of the respective first shaft (4) so as to act as ailerons/elevons in the retracted position.

Abstract: A method of determining performance characteristics of a flow machine having a rotor interacting with a flow field. The method comprises: receiving performance data for the flow machine comprising data values of a performance parameter of the rotor and mass flow for the flow machine at one or more defined rotor condition, the performance data defining a two-dimensional array of data in which points for a common rotor condition are identifiable; determining or receiving exit mass flow values for the flow downstream of the rotor; and identifying one or more point in the received performance data and interpolating from said one or more point to a corresponding one or more point at a different rotor condition based on a correlation of the exit mass flow values for said points.

Abstract: A VTOL aircraft has fixed wings and a rotor blade system for providing lift in active and passive modes thereof. Operation of the rotor blade system may be switched between the active mode in which the rotor blade system is driven by a power system of the aircraft and the passive mode in which the rotor blade system is not driven by the power system, the rotor blade system being configurable to provide lift in the passive mode during forward flight of the aircraft. The rotor blade system provides lift in the passive mode, allowing the fixed wings to be shorter than in the case where the rotor system provides lift during vertical take-off and landing but otherwise has no function, thus providing aircraft which is lighter, more compact and more efficient than similar aircraft of the prior art.

Abstract: A lift rotor arrangement (100) for a VTOL aircraft (200). The lift rotor arrangement (100) comprises: a fairing (6) mounted on a wing segment (10); and first and second rotor blades (17, 18) mounted on a first shaft (4) extending vertically from the fairing (6). The first shaft (4) is movable between an extended position in which the first and second rotor blades (17, 18) are vertically spaced above the wing segment (10) and are rotatable to provide vertical lift, and a retracted position in which the first and second rotor blades (17, 18) are rotationally-fixed with the first rotor blade (17) stowed within the wing segment (10). The blades (17, 18) may be rotatable around an axis substantially perpendicular to the axis of the respective first shaft (4) so as to act as ailerons/elevons in the retracted position.

Abstract: A system for providing active flow control in an aircraft having a gas turbine engine. The system includes an environmental control system that includes a cabin blower system having a compressor operable to compress a fluid delivered by a fan section of the gas turbine engine to generate a pressurised fluid for use by the environmental control system. The environmental control system is fluidicly connected to an active flow control system via a fluid supply line, for allowing the pressurised fluid generated by the compressor to be supplied to the active flow control system so that it can be ejected from the aircraft across an exterior surface of a movable control element of the aircraft.

Abstract: An aircraft environmental control system (20) comprises a first heat exchanger (24) configured to exchange heat between air provided by a pressurised air source (13), and a working fluid of a closed cycle waste heat recovery system, and an air turbine (32) configured to receive cooled air from the first heat exchanger (24). The closed cycle waste heat recovery system comprises a waste heat recovery compressor (35), a waste heat recovery turbine (31), and a second heat exchanger (33) configured to exchange heat between working fluid of the closed cycle waste heat recovery system and air downstream of the air turbine (31). The air turbine is configured to drive a load (39), and the waste heat recovery turbine (31) is configured to drive the waste heat recovery compressor (35).

Abstract: An aircraft environmental control system (20) comprises a first heat exchanger (24) configured to exchange heat between air provided by a pressurised air source (13) and a working fluid of a closed cycle refrigeration system, and an air turbine (32) configured to receive cooled air from the first heat exchanger (24). The closed cycle refrigeration system comprises a closed cycle refrigeration system compressor (35) driven by the air turbine (32), a closed cycle refrigeration system expander (36), and a second heat exchanger (33) configured to exchange heat between working fluid of the closed cycle refrigeration system and air downstream of the air turbine (32). The air turbine drives a further load (39).

Abstract: A gas turbine engine variable guide vane has a fixed portion on an upstream side, a movable flap on a downstream side and a transfer slot between a fixed portion trailing surface and a movable flap leading surface. The movable flap has opposite pressure and suction sides along a chord line between leading and trailing edges, and is rotatable about an axis along a movable flap span over a range of angular positions between open and closed. The trailing surface has a substantially U-shaped profile with first and second branches respectively partially around the pressure and suction sides. The transfer slot has inlet and exhaust ports respectively on the pressure and suction sides. In the closed position the suction side contacts the second branch closing the exhaust port, and in the open position the second branch directs a first air flow through the transfer slot tangentially over the suction surface.

Abstract: A gas turbine engine variable guide vane has a fixed portion on an upstream side, a movable flap on a downstream side and a transfer slot between a fixed portion trailing surface and a movable flap leading surface. The movable flap has opposite pressure and suction sides along a chord line between leading and trailing edges, and is rotatable about an axis along a movable flap span over a range of angular positions between open and closed. The trailing surface has a substantially U-shaped profile with first and second branches respectively partially around the pressure and suction sides. The transfer slot has inlet and exhaust ports respectively on the pressure and suction sides. In the closed position the suction side contacts the second branch closing the exhaust port, and in the open position the second branch directs a first air flow through the transfer slot tangentially over the suction surface.