Abstract: A nozzle guide vane for a gas turbine engine having a combined side wall thickness value which varies within a cavity region so as to provide a point with a maximum value of combined side wall thickness, which is advantageous for capturing debris travelling through the engine core.

Abstract: Electrical power system includes: one or more rotary electric machines, each mechanically coupled to a gas turbine engine spool; a set of converter circuits connected to the one or more rotary electric machines for conversion between alternating (ac) and direct current (dc), wherein one or more rotary electric machines and the set of converter circuits are arranged to output a number R?2 of dc power channels, each dc power channel having a respective index r=(1, . . . , R); and a group of N dc load channels connected to the R dc power channels by a switching arrangement, wherein N>R and each dc load channel has a respective index n=(1, . . . , N). The switching arrangement is operable to connect a number Q?1 of the N load channels to at least two different power channels of the R power channels.

Abstract: A gas turbine engine for an aircraft comprises an engine core comprising a turbine, a compressor, and a core shaft connecting the turbine to the compressor, wherein a compressor exit temperature is defined as an average temperature of airflow at the exit from the compressor; and a fan located upstream of the engine core, the fan comprising a plurality of fan blades extending from a hub, each fan blade having a leading edge and a trailing edge, wherein a fan rotor entry temperature is defined as an average temperature of airflow across the leading edge of each fan blade at cruise conditions and a fan tip rotor exit temperature is defined as an average temperature of airflow across a radially outer portion of each fan blade at the trailing edge at cruise conditions. A core to fan tip temperature rise ratio is in the range from 2.845 to 3.8.

Abstract: A electrical power system comprises: an electrical machine operable to output AC; a DC electrical network; a power electronics converter connected between the AC output of the electrical machine and the DC electrical network and including a plurality of transistors and associated diodes connected in parallel with the transistors; and a controller configured to control switching of the transistors of the converter so that, during normal operation of the electrical power system, the converter rectifies the AC output of the electrical machine to supply the DC electrical network with DC electrical power. The controller is further configured, responsive to a determination to the effect there is a fault in the DC electrical network, to control a voltage source, to inject a voltage to bias the diodes of the converter, and to control the switching of the transistors to control a level of current supplied to the faulted DC electrical network.

Abstract: An aircraft propulsion system comprises a gas turbine engine arranged to provide propulsive thrust and a fuel cell system having an air input port, the aircraft propulsion system being configured such that air from a compressor of the gas turbine engine is provided to the air input port during operation of the aircraft propulsion system. The fuel cell system is able to provide appreciable electrical power at altitude without the need for a dedicated compressor.

Abstract: An electrical power system includes: an electrical machine to output AC; DC electrical network; power electronics converter connected between the AC output of the electrical machine and the DC electrical network and having a phase leg having first and second branches respectively having first and second bi-directional MOSFETs; and controller controlling switching of the first and second bi-directional MOSFETs of each phase leg of the converter so that current is commutated between the phase leg first and second branches rectifying the AC input to DC to supply the DC electrical network with DC electrical power. The controller is responsive to a determination to the effect that there is a fault in the DC electrical network, to control the switching of each phase leg first and second bi-directional MOSFETs to switch the converter into a crow-bar configuration in which electrical machine current does not flow to the DC network.

Abstract: A bladed disc system for a turbine engine, the bladed disk portion comprising a disk portion and a plurality of blade portions, the disc portion being shaped such that the blade portions are able to fit within fir tree slot in the disc portion, the blade portion comprising an aerofoil section and a root section, with the root section comprising a fir tree profile and a skirt portion and wherein the skirt portions of adjacent blades form an opening that has a maximum separation of between 1-50% of the maximum skirt opening width.

Abstract: A particle gripper comprising a flexible surface membrane connected to a resiliently deformable neck portion which has a cavity filled with a phase change material, and at least one air tube, the flexible surface membrane and the phase change material are configured to deform around an object to be gripped; and wherein the at least one air tube is used for inflating and/or creating a vacuum within the cavity such that the cavity can be inflated so that the phase change material is forced against the flexible surface membrane to expand the flexible surface membrane, and a transition means which is applied to the phase change material in the cavity so that it changes phase of the material from a liquid to a solid so that object is gripped by the flexible surface membrane and the phase transition material.

Abstract: A method of controlling an electric propulsion system of an aircraft. The propulsion system comprising an electric motor configured to drive a variable pitch propulsor. The method comprises determining a commanded thrust setting; determining one or more flight parameters; determining either a corresponding rotor governor speed and motor torque set-point, or a corresponding motor speed and rotor pitch angle set point, which provides the commanded thrust setting at the determined flight parameter having a maximum propulsion system efficiency; and controlling the rotor governor and electric motor in accordance with the determined respective set-points.

Abstract: A bladed disc system for a turbine engine having a disk portion and a plurality of blade portions which are associated with a stator section and an intercavity sealing portion, disc portion shaped such that blade portions are able to fit within firtree slot in disc portion, blade portion having aerofoil section and root section, aerofoil section having portion shaped such that they extend proximate to intercavity sealing portion, disc portion extending from portion that connects with drum to outer edge at which blade portions are connected with disc portion having width transition region in which thickness of disc increases from point at which disc connects to drum to outer edge at which it holds blade portions, and wherein width transition region has curved width transition region with radius r, and an overhanging portion which extends into the intercavity spacing between the width transition region and the intercavity sealing portion.

Abstract: A planetary gearbox having a sun gear, a plurality of planet gears, a ring gear, and a plurality of journal bearing pins. At its axially forward face side and/or at its axially rearward face side, each planet gear forms a recess that extends inside the planet gear starting from the face side. The planet gear forms a protrusion at its axially forward face side and/or at its axially rearward face side. The protrusion has an axial extent and a radial extent, wherein the radial extent is limited at the respective face side to the area between the planet gear inner bore and the radial inner limit of the respective recess in the planet gear, and wherein the protrusion is configured to provide for a flow path for oil emerging from the journal bearing that guides the oil away from the journal bearing.

Abstract: A method of controlling a gas turbine engine includes the steps of: detecting a shaft break event in a shaft connecting a compressor of the gas turbine engine to a turbine of the gas turbine engine; and in response to this detection, activating a shaft break mitigation system which introduces a fluid into a gas flow of the gas turbine engine downstream of the turbine, or increases an amount of a fluid being provided into the gas flow of the gas turbine engine downstream of the turbine, whereby the fluid reduces an effective area of a nozzle for the gas flow so as to reduce the mass flow rate of the gas flow through the turbine.

Abstract: A gas turbine engine generates noise during use, and one particularly important flight condition for noise generation is take-off. A gas turbine engine that has high efficiency provides low noise, in particular from the fan and the turbine that drives the fan. Values are defined for a noise parameter NP that results in a gas turbine engine having reduced combined fan and turbine noise.

Abstract: A method may include cold spraying a masking material on selected locations of a component to form a masking layer, wherein the masking material comprises a metal or alloy; additively manufacturing an additively manufactured portion of the component at locations at which the masking layer is not present; and removing the masking layer from the component. The masking layer may be configured to protect portions of the component by covering or otherwise providing a physical barrier that reduces or prevents material from adhering to unwanted portions of the component during a subsequent manufacturing and/or repair technique. Additionally, the masking layer may be reflective to infrared radiation and/or intimately contact the component and function as a heat sink or thermally conductive layer to transfer heat from the component.

Abstract: A gas turbine engine including: a high pressure turbine, a low pressure turbine, a high pressure compressor coupled to the high pressure turbine by a high pressure shaft, a propulsor and a low pressure compressor coupled to the low pressure turbine via a low pressure shaft and a reduction gearbox; wherein the high pressure compressor defines an average stage pressure ratio at cruise conditions of between 1.25 and 1.35 and consists of 10 or 11 stages; and the high pressure compressor and low pressure compressor together define a core overall pressure ratio at cruise conditions of between 40:1 and 60:1.

Abstract: A method of joining a first component to a second component at respective connection surfaces, comprising, in order, applying a local surface treatment to the connection surface of at least one of the first and second components in order to locally alter the microstructure to a depth of between 60 ?m and 10 mm below the connection surface; and joining the first component to the second component using a welding process.

Abstract: Electrical power systems for distributing electrical power in aircraft are described. One such electrical power system comprises: an electrical power source configured to output a number R?2 of dc power channels, each dc power channel having a respective index r=(1, . . . , R); and a group of N dc load channels connected to the R dc power channels by a switching arrangement, wherein N>R and each dc load channel has a respective index n=(1, . . . , N). The system further comprises, for each respective one of a plurality of the N load channels, a current limiting device (CLD) operable to limit an amount of current flowing from the power channels to a load connectable to the electrical power system via the respective load channel. The electrical power source may comprise one or more batteries.

Abstract: A gas turbine engine generates noise during use, and one particularly important flight condition for noise generation is take-off. A gas turbine engine that has high efficiency provides low noise, in particular from the fan and the turbine that drives the fan. Values are defined for a noise parameter NP that results in a gas turbine engine having reduced combined fan and turbine noise.

Abstract: A gas turbine engine for an aircraft. The gas turbine comprises a staged combustion system having pilot injectors and main injectors, a fuel metering system configured to control fuel flow to the pilot injectors and the main injectors, and a fuel system controller. The controller is configured to identify an atmospheric condition, determine a ratio of pilot fuel flow rate for the pilot injectors to main fuel flow rate for the main injectors in response to the atmospheric condition, and inject fuel by the pilot injectors and the main injectors in accordance with said ratio to control an index of soot emissions caused by combustion of fuel therein.

Abstract: A gas turbine engine, and an aircraft including the gas turbine engine. The gas turbine engine comprising: an engine core comprising a turbine, a compressor, and a shaft system connecting the turbine to the compressor. The shaft system is axially located by a thrust bearing located forward of the turbine, and the engine is configured such that, 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; and the engine further comprises an axial movement sensor configured to register a shaft break when it detects the axial movement of the rear portion of the shaft system.