Abstract: An aircraft includes a machine body that encloses a turbofan gas turbine engine and a plurality of ancillary systems. The turbofan gas turbine engine includes, in axial flow sequence, a first heat exchanger module, a fan assembly, a compressor module, a combustor module, a turbine module, and an exhaust module. The aircraft includes a second heat exchanger module. The machine body comprises a single fluid inlet aperture, with the fluid inlet aperture being configured to allow a fluid cooling flow to enter the machine body and to pass through the first heat exchanger module. When a temperature of the fluid cooling flow is less than a temperature of a fluid to be cooled, the fluid to be cooled is directed to the first heat exchanger module, and when a temperature of the fluid cooling flow is greater than a temperature of the fluid to be cooled, the fluid to be cooled is directed to the second heat exchanger module and cooled using a fuel supply for the gas turbine engine.

Abstract: A composite gas storage tank includes a composite wall defining a main storage volume and a hollow conduit portion communicating with and extending away from the main storage volume. A hollow coupling element has a length portion which is partially embedded within and extends substantially parallel to the hollow conduit portion of the composite wall. The hollow conduit portion and the coupling element provide communication between the main storage volume and the tank exterior. A leakage path around the hollow coupling element is significantly longer than those of tanks of the prior art and reduces the rate at which hydrogen leaks from the tank. A carbon fibre filament winding extends over the length of the hollow conduit portion and provides a radially inwardly-directed force biasing the carbon fibre material of the hollow conduit portion into contact with the coupling element, further reducing the leakage rate on the leakage path.

Abstract: A direct injection fuel system is shown for injecting hydrogen fuel into a gas turbine combustor. The fuel injection system includes a plurality of fuel injector blocks. Each fuel injector block includes a fuel admission duct having an inlet for receiving hydrogen fuel from a fuel supply, an outlet for delivering hydrogen fuel into the combustor and a central axis extending from said inlet to said outlet. Each fuel injector block also includes an air admission duct located around the periphery of the fuel admission duct, having an inlet for receiving air from a diffuser and an outlet for delivering air into the combustor for mixing with the hydrogen fuel.

Abstract: In some examples, an article may include a substrate and a coating system on the substrate. The coating system may include a layer comprising a plurality of voids, wherein respective voids of the plurality of voids define respective void volumes; and a nucleating agent within at least some of the respective void volumes of the layer, wherein the nucleating agent is configured to induce crystallization of the molten CMAS. The coating system may include an environmental barrier coating, thermal barrier coating, and/or abradable coating.

Abstract: There is disclosed a method of inserting a reinforcing rod into a hole in a laminated material. The method comprises a feed operation in which a feed clamp clamps a rod whilst moving towards the laminated material to feed an end section of the rod through a guide clamp into a hole in the laminated material. The method further comprises a re-supply operation in which the feed clamp releases the rod and moves relative the rod along a return direction away from the laminated material whilst the guide clamp clamps the rod. A corresponding insertion head for inserting a reinforcing rod, and insertion equipment comprising the insertion head and a controller is also disclosed.

Abstract: A vane for a gas turbine engine, the vane including a platform with an airfoil extending radially from the upper surface of the platform. The platform includes a joint portion which includes a circumferentially extending flange and a recessed surface both formed on either the upper or lower surface of the platform. The flange and the recessed surface extend from opposing circumferential edges of the joint portion and each include a substantially radially-extending through hole.

Abstract: Electrical power systems for distributing electrical power in arrangements including one or more gas turbine engines; one such system includes: one or more rotary electric machines, coupled to a gas turbine engine spool; converter circuits connected to the rotary electric machines converting between alternating current (ac) and direct current (dc), wherein the rotary electric machines and the converter circuits output a number R?2 of dc power channels, each channel having an index r=(1, . . . , R); and a group of N dc load channels connected to the R dc power channels by a switching arrangement, wherein each dc load channel has an index n=(1, . . . , N) and R<N?2R.

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: There is provided an air pressurisation system comprising: a blower compressor coupled to a spool of a gas turbine engine and configured to receive inlet air from a bypass duct of the gas turbine engine; an air treatment apparatus to mix air from the air cycle line with air from the bypass line to control a temperature of air for discharge to an airframe system; and a core bleed line configured to provide a second inlet flow of air from a compressor of the gas turbine engine to the air treatment apparatus in an augmented air supply mode of the air pressurisation system; wherein the core bleed line is configured to provide the second inlet flow of air directly to the bypass line or mix the second inlet flow of air with air from the blower compressor upstream of the bypass line.

Abstract: A system for use with a component of a power generation apparatus includes a lens arrangement disposed proximal to the component. The system further includes a variable focal length structure spaced apart from the lens arrangement and optically coupled with the lens arrangement. The variable focal length structure has a focal plane that is adjustable. The system further includes a controller communicably coupled with the variable focal length structure. The controller is configured to control the variable focal length structure to adjust the focal plane of the variable focal length structure, such that at least one region of interest of the component is in focus.

Abstract: A power electronics converter comprising: first and second input terminals; first and second DC output terminals; a branch comprising first and second semiconductor switches connected in series between the first and second DC output terminals, the first input terminal connected to a node between the first and second semiconductor switches; a DC link capacitor connected between the first and second DC output terminals; and a reverse biased DC link diode connected across the DC link capacitor.

Abstract: A method for improving the corrosion and fatigue crack resistance of an article that has a surface. The method involves: providing a dry powder having one or more anti-corrosion materials; pressurising the dry powder to 1 to 5 MPa in an inert gas; pre-heating the surface of the article to a temperature of 50 to 900° C. and cold-spraying the surface of the article with the dry powder at a particle velocity of 300 to 1200 m/s so that a corrosion and crack-resistant coating is formed on the surface of the article and the surface is modified to an average depth of 10 to 100 ?m.

Abstract: A blade for use in a gas turbine engine, the blade comprising a blade portion and a fir tree root portion, the blade portion and the root portion having a connected passage for allowing cooling air to flow within the blade, the fir tree root portion having an air intake on its leading edge, the air intake allowing cooling air to enter the cooling passage and wherein the fir tree root portion comprises a plurality of projections, including at least a base projection and a top projection; and wherein the air inlet located in the base projection of the fir tree root portion and wherein the air inlet comprises at least 50% of the face of the base projection of the fir tree root portion.

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: In some examples, a method comprising: controlling a first ratio of a first liquid to a second liquid to form a first suspension comprising a powder and a first carrier liquid composition comprising at least one of the first liquid or the second liquid; directing the first suspension comprising the first carrier liquid and the powder to a plume of a thermal spray device; forming a first portion of a coating comprising the powder on a substrate from the first suspension; controlling a second ratio of the first liquid to the second liquid to form a second suspension comprising a second carrier liquid composition and the powder; directing the second suspension comprising the second carrier liquid composition and the powder to the plume of the thermal spray device; and forming a second portion of the coating comprising the powder on the substrate from the second suspension.

Abstract: The present disclosure relates to a geared gas turbine engine for an aircraft. Example embodiments include a gas turbine engine for an aircraft including: an engine core having a turbine, a compressor, and a core shaft connecting the turbine to the compressor; a fan located upstream of the engine core, the fan having a plurality of fan blades; and a gearbox that receives an input from the core shaft to drive the fan at a lower rotational speed than the core shaft, the gearbox having a gear ratio of around 3.4 or higher, wherein the gas turbine engine is configured such that a jet velocity ratio between a first jet velocity exiting from a bypass duct of the engine and a second jet velocity exiting from an exhaust nozzle of the engine core is within a range from around 0.75 to around 0.82.

Abstract: A combustion system comprising: a combustion chamber extending in an axial direction between an inlet and an outlet, the combustion chamber configured to receive an airflow through the inlet and to discharge the airflow through the outlet; a fuel injection port configured to inject fuel into the airflow to form an air-fuel mixture; an ignition system for igniting the air-fuel mixture in the combustion chamber, the ignition system comprising an array of electrical plasma initiation points disposed downstream of the fuel injection port, and distributed radially and circumferentially around the combustion chamber, wherein each electrical plasma initiation point comprises a pair of electrodes configured to apply a voltage across an electrode gap between the pair of electrodes to produce plasma within the air-fuel mixture passing between the electrodes, thereby igniting the air-fuel mixture.

Abstract: An aircraft has first and second fuel sources containing fuels with different characteristics, and one or more gas turbine engines powered by the fuels and each having a staged combustion system having pilot and main fuel injectors and being operable in pilot-only and pilot-and-main ranges of operation. The gas turbine engines each have a fuel delivery regulator arranged to control fuel delivery to the pilot and main fuel injectors. The method includes: obtaining a proposed mission description; obtaining nvPM impact parameters for the gas turbine engines, the impact parameters being associated with each operating condition of the proposed mission; calculating an optimised set of one or more fuel characteristics for each flight condition of the proposed flight defined in the flight description based on the nvPM impact parameters; and determining a fuel allocation based on the optimised set of one or more fuel characteristics.

Abstract: A method of optimising the performance of combustion equipment of a gas turbine engine includes providing a fuel flow into the combustion equipment via a plurality of fuel injectors circumferentially disposed about a principal rotational axis at a plurality of injector positions; determining a plurality of temperatures of combustion gases at a plurality of circumferential positions downstream of the combustion equipment using a plurality of temperature measurement devices; ranking the plurality of circumferential positions based on the plurality of temperatures of the combustion gases determined using the plurality of temperature measurement devices; and repositioning at least some of the plurality of fuel injectors between the plurality of injector positions based at least on the ranking of the circumferential positions.

Abstract: A method of operating an aircraft including a gas turbine engine and a plurality of fuel tanks arranged to provide fuel to the gas turbine engine, where at least two of the fuel tanks contain fuels with different fuel characteristics. The method includes obtaining a flight profile for a flight of the aircraft; and determining a fuelling schedule for the flight based on the flight profile and the fuel characteristics. The fuelling schedule governs the variation with time of how much fuel is drawn from each tank. Fuel input to the gas turbine engine may then be controlled in operation in accordance with the fuelling schedule.