Abstract: A hydrogen-fuelled aircraft power system incorporates a gas turbine engine and a fuel cell, in which air supply and cooling of the fuel cell is integrated with the gas turbine engine to improve overall efficiency of the power system. The system may be part of a turbofan, turboprop or electric propulsion system for an aircraft.

Abstract: An electrical power system including: an electrical power source, a power electronics converter, an electrical network, a current limiting diode and a controllable circuit interruption device, wherein: the current limiting diode is configured to limit a fault current passing between the electrical power source and the electrical network in a fault condition; and the controllable circuit interruption device is configured to interrupt the fault current in response to a determination that the electrical power system is in the fault condition.

Abstract: A gas delivery system intended for use in delivering hydrogen gas from a cryogenic liquid hydrogen storage tank is provided. The gas delivery system has: a cryogenic liquid storage tank; an evaporator; a pressurisable gas reservoir; a valve sub-system including: a multi-outlet valve arrangement having a first valve inlet, a first valve outlet and a second valve outlet; and a multi-inlet valve arrangement having a second valve inlet, a third valve inlet and a third valve outlet; a delivery line connected to the third valve outlet; an evaporator feed line connecting the storage tank and the evaporator inlet; an evaporator dispensing line connecting the evaporator and the first valve inlet; a reservoir feed line connecting the first valve outlet and the reservoir; a reservoir dispensing line connecting the reservoir and the second valve inlet; and a reservoir bypass line connecting the second valve outlet and the third valve inlet.

Abstract: Disclosed is an aircraft accessory drive system comprising: a drive shaft configured to provide a drive input; a critical accessory directly coupled to the drive shaft so as to be directly driven by the drive shaft; a parasitic drive system configured to transmit drive input from the drive shaft to one or more less critical accessories, wherein the parasitic drive system comprises a torque limiter configured to decouple the parasitic drive system from the drive shaft and the critical accessory in response to a jam affecting the parasitic drive system or one or more of the less critical accessories. Also disclosed are a gas turbine engine comprising an aircraft accessory drive system, and an aircraft comprising an aircraft accessory drive system.

Abstract: A hydrogen-fuelled gas turbine engine has a fuel input path from a fuel input of the engine to a combustor, the engine further comprising a heat-exchanger located in the fuel input path and a fuel turbine located in the fuel input path between the heat-exchanger and the combustor. The heat-exchanger is arranged to receive waste heat from the engine core in order to heat hydrogen fuel introduced at the fuel input prior to input thereof to the combustor. The engine further comprises an air compressor arranged to be driven by the fuel turbine. The engine provides for most of the waste heat of combustion to be recovered and used without the need for heavy electrical or mechanical apparatus and is therefore particularly advantageous in aeronautical applications.

Abstract: A method of forming a protective coating includes providing a substrate including a major surface. The method further includes providing a top coat layer adjacent to the major surface of the substrate. The top coat layer includes a top coat surface distal to the substrate. The method further includes forming a plurality of slots in the top coat layer. The method further includes at least partially heating the top coat surface above a threshold temperature, such that a first portion of the top coat layer extending from the top coat surface partially melts to form a glazed layer, and a second portion of the top coat layer disposed between the glazed layer and the major surface of the substrate is not melted and includes at least a portion of each of the plurality of slots.

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 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: 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: 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 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 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 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 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 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 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.