Abstract: A gas turbine engine for an aircraft includes an engine core including an engine core, a turbine, a compressor, and a core shaft connecting the turbine to the compressor, the turbine comprising a lowest pressure rotor stage, the turbine having a turbine diameter at the lowest pressure rotor stage. A fan located upstream of the engine core, the fan comprising a plurality of fan blades extending from a hub, the hub and fan blades together defining a fan face having a fan face area and a fan tip radius. A ratio of the fan tip radius to the turbine diameter at the lowest pressure rotor stage is in the range from 1.2 to 2.0.

Abstract: Performing multivariate spectral analysis to determine relationships between chemical species in a sample, includes: providing intensity measurement data as plural measured spectra from the sample, each spectrum having unique identifier and intensity values for bins of a binned spectral range; expressing the intensity measurement data as an m×n matrix V, m and n respectively represents number of bins of the spectral range and number of unique identifiers; performing non-negative factorisation of the matrix V to obtain an m×p derived spectra matrix W and a p×n spectral weightings matrix H minimizing an error function ?V-WH?, p representing a number of derived spectra and is selected such that the non-negative factorisation over-fits WH to V; identifying correlations between the p derived spectra of the derived spectra matrix W which explain variance in the intensity measurement data; and determining chemical relationships between chemical species in the sample.

Abstract: A gas turbine engine, includes: an engine core including a turbine, compressor, and shaft system connecting the turbine to the compressor, and forming a torque path therebetween. The shaft system is axially located by a thrust bearing located forward of the turbine, and the engine is configured, in the event of a shaft break which divides the shaft system into a front portion located by the thrust bearing and a rear portion unlocated by the thrust bearing, the rear portion is free to move axially rearwardly under a gas load. The engine further includes a shaft break detector having a forward speed sensor configured to measure a rotational speed of the front portion of the shaft system, and a rear microwave sensor configured to measure a rotational speed of the rear portion of the shaft system, wherein a shaft break can be detected based on differences in the measured speeds.

Abstract: A lean burn fuel injector has a head which has a coaxial arrangement of an inner pilot air-blast fuel injector and an outer main air-blast fuel injector. The pilot fuel injector comprises coaxially arranged inner and outer air swirler passages. The main fuel injector comprises coaxially arranged inner and outer air swirler passages. A first splitter is arranged between the passages. The first splitter has a conical divergent downstream portion. A second splitter is arranged radially within and spaced from the first splitter. The second splitter has a conical convergent portion and a conical divergent downstream portion. The downstream end of the second splitter is upstream of the downstream end of the first splitter. A connecting member connects the downstream end of the second splitter and the downstream portion of the first splitter upstream of the downstream end of the first splitter to form a sharp edge.

Abstract: A gas turbine engine for an aircraft and a method of operating a gas turbine engine on an aircraft. Embodiments disclosed include a gas turbine engine for an aircraft including: an engine core has a turbine, a compressor, and a core shaft; a fan located upstream of the engine core, the fan has a plurality of fan blades; a nacelle surrounding the engine core and defining a bypass duct and bypass exhaust nozzle; and a gearbox that receives an input from the core shaft and outputs drive to the fan wherein the gas turbine engine is configured such that a jet velocity ratio of a first jet velocity exiting from the bypass exhaust nozzle to a second jet velocity exiting from an exhaust nozzle of the engine core at idle conditions is greater by a factor of 2 or more than the jet velocity ratio at maximum take-off conditions.

Abstract: A gas turbine engine includes a gearbox receiving input from a core shaft and driving a fan at a lower speed than the core shaft. First and second oil circuits fluidly couple with an inlet and outlet of the gearbox. A third oil circuit fluidly couples with an inlet and outlet of the gearbox. The outlet of the gearbox includes a device directing oil from the gearbox to the first oil circuit, to the second oil circuit and to the third oil circuit when feeding to the gearbox exceeds a predefined oil flow rate, or deviates an operational value corresponding with that oil flow rate, and directs oil from the gearbox to the third oil circuit when feeding to the gearbox is ? the predefined flow rate or is ? a corresponding operational value or is greater than or equal to a further corresponding operational value.

Abstract: A coated substrate comprising a metal or metal alloy such as a high speed steel, TiAl based alloy or Ni based alloy or an electrically conductive ceramic material, wherein the coating comprises a hard material protective coating comprising alternating layers of different compositions, wherein a first composition of the alternating layers comprises silicon, Si, and/or a second composition of the alternating layers comprises boron, B.

Abstract: An annulus filler for mounting to a rotor disc in a gas turbine engine includes a body portion having a top wall arranged to bridge the gap between two adjacent blades extending from the rotor disc and to define an air flow surface for air passing between the blades; and a separately formed rear interface portion, fixed to the body portion adjacent to a down-flow end of the top wall. The rear interface portion forms a lip projecting below the top wall.

Abstract: A method and apparatus for finishing a surface of a metal component made by additive manufacturing are provided. The method comprises: containing the component 41 in a fluid 43 that comprises abrasive particles 48; and generating pressure fluctuations that produce acoustic cavitation in the fluid by applying ultrasonic vibration into the fluid by an ultrasonic horn 45, thereby removing material from the surface of the component by a combination of cavitation bubble collapse on the surface and the striking of the surface by abrasive particles 48 accelerated by cavitation bubble collapse.

Abstract: The present disclosure concerns control a hybrid electric gas turbine system (300) for an aircraft. The system comprises an electric generator (308) and a gas turbine (309) to form a generator system, an electric motor (303) and a fan (302) to form a propulsor (301), a controller (306) and an electric storage unit (307). After receiving a command for a change in demand for thrust, the controller (306) determines an operational profile that minimises a function comprising a measure of fuel supplied to the gas turbine (309), a transfer of electric power from or to the electric storage unit (307) and a difference between measures of current and demanded thrust over a time period. The controller then operates the electric motor (303), gas turbine (309) and electric storage unit (307) according to the determined operational profile over the time period.

Abstract: A method of analysing a component formed from a metal alloy to identify a possible defect, wherein the metal alloy comprises a first crystal grain region and the possible defect comprises a second crystal grain region aligned to a different axis to the first crystal grain region, the method comprising the steps of: obtaining a first image of the component illuminated using a first polarisation state of light, the first image comprising first polarisation data; obtaining a second image of the component illuminated using a second polarisation state of light different to the first polarisation state, the second image comprising second polarisation data; determining a difference in polarisation data for plural pixels of the first image between each pixel of the first image and a corresponding pixel of the second image; and identifying pixels corresponding to the second crystal grain region based on the difference in polarisation data.

Abstract: A method (500) and apparatus (50, 60) for lubrication of a gearbox (30) of an aircraft engine comprise provision (502) of oil to the gearbox (30) through a primary oil system (50) driven by a core (11) of the engine (10) in normal conditions; detection (504) of windmilling conditions and/or failure of the primary oil system (50); and in response to the detected condition or failure, activation (506) of an electric pump (61) of an auxiliary oil system (60), to provide oil to the gearbox (30).

Abstract: A core duct assembly for a gas turbine engine includes a core duct including an outer and an inner wall, the outer wall having an interior surface; a gas flow path member extending across the gas flow path at least partly between the inner and outer walls, the rotor blade having a radial span extending from a blade platform to a blade tip, wherein an upstream wall axis is defined as an axis tangential to a point on a first portion of the interior surface of the outer wall of the core duct extending downstream from the gas flow path member, the upstream wall axis lying in a longitudinal plane of the gas turbine engine containing the rotational axis of the engine, and wherein the upstream wall axis intersects the rotor blade at a point spaced radially inward from the blade tip of the rotor blade.

Abstract: There is disclosed a composite material lay-up head (20) for applying elongate fibre reinforcement material (14) to a tool (12), the head (20) comprising: at least one elongate tow guide channel (32) for guiding fibre reinforcement material (14) from a tow inlet (33) to a tow outlet (35) of the channel (32); and feed apparatus (36, 38) for feeding fibre reinforcement material through the at least one channel (32); wherein the or each channel (32) is provided with at least one nozzle (60) arranged so that in use a jet of gas can be delivered into the channel (32) so as to inhibit contact between fibre reinforcement material (14) in the channel (32) and the channel (32).

Abstract: A fan blade containment system is arranged to surround a fan including a plurality of fan blades in a gas turbine engine for an aircraft. The fan blade containment system includes a composite fan case arranged to surround the fan; and a metallic insert mounted on the composite fan case and including a metallic hook arranged to prevent forward debris release should all or part of a fan blade become detached from the fan.

Abstract: A gas turbine engine includes an engine core including: a compressor system including first, lower pressure, compressor, and a second, higher pressure, compressor; and an outer core casing surrounding the compressor system and including a first flange connection arranged to allow separation of the outer core casing at an axial position of the first flange connection, wherein the first flange connection is the first flange connection that is downstream of an axial position defined by the axial midpoint between the mid-span axial location on the trailing edge of the most downstream aerofoil of the first compressor and the mid-span axial location on the leading edge of the most upstream aerofoil of the second compressor; a nacelle surrounding the engine core and defining a bypass duct between the engine core and the nacelle; wherein an axial midpoint of the radially outer edge is defined as the fan OGV tip centrepoint.

Abstract: Disclosed herein is a converter for converting an AC voltage to a DC voltage, the converter comprising: a first H-bridge circuit comprising a first AC terminal for receiving an AC voltage, a second AC terminal, a first DC terminal and a second DC terminal; a second H-bridge circuit comprising a first AC terminal for receiving an AC voltage, a second AC terminal, a first DC terminal and a second DC terminal; an isolation block arranged between the second AC terminal of the first H-bridge circuit and the second AC terminal of the second H-bridge circuit; and a DC voltage output of the converter with a first terminal and a second terminal; wherein: the first terminal of the DC voltage output is connected to the first DC terminal of the first H-bridge circuit and the first DC terminal of the second H-bridge circuit; and the second terminal of the DC voltage output is connected to the second DC terminal of the first H-bridge circuit and the second DC terminal of the second H-bridge circuit.

Abstract: A fan blade containment system is arranged to surround a fan including a plurality of fan blades in a gas turbine engine for an aircraft. The fan blade containment system includes a fan case arranged to surround the fan; a debris retainer, such as a front hook, mounted on the fan case and arranged to prevent forward debris release should all or part of a fan blade become detached from the fan; and a front panel mounted on the fan case adjacent to and rearward of the front hook, and arranged to move or break when struck by a detached fan blade or fan blade part so as to allow the detached fan blade or fan blade part to engage the front hook.