Abstract: An aerofoil structure with a hollow cavity is manufactured by diffusion bonding and superplastic forming. Outer panels are formed of a first material; a membrane is formed of a second material. Stop-off material is applied to preselected areas on at least one side of the membrane or of one of the panels so as to prevent diffusion bonding between the panels and the membrane at the preselected areas. The panels and the membrane are arranged in a stack and a diffusion bonding process is performed to bond together the first and second panels and the membrane to form an assembly. A superplastic forming process is performed at a forming temperature to expand the assembly to form the aerofoil structure. The forming temperature is selected so that the second material undergoes superplastic deformation at the forming temperature and the first material does not undergo superplastic deformation at the forming temperature.

Abstract: An aircraft gas turbine engine nacelle comprising a thrust reversal arrangement. The thrust reversal arrangement comprises at least one thrust reverser cascade box comprising a fixed structure and a plurality of thrust reverser vanes configured to direct bypass air forwardly. At least a subset of the thrust reverser vanes are pivotable and/or translatable relative to the fixed structure between a deployed position, in which the vanes define a first volume, and a stowed position, in which the pivotable vanes define a second, smaller volume.

Abstract: There is disclosed a method for diagnosing a fault condition in an electric machine 4, the electric machine 4 comprising a rotor 10 having an axis of rotation 14 and comprising a plurality of permanent magnets M1-M8. The method comprises: rotating the rotor 10 so that each of the plurality of permanent magnets M1-M8 passes a magnetic flux density sensor 6; measuring values of magnetic flux density using the magnetic flux density sensor 6 at a plurality of positions of the rotor 10; analysing the measured values of magnetic flux density and comparing a magnitude of a peak amplitude in a time or frequency domain with a reference value; and if the peak amplitude is below the reference value, determining that the electric machine 4 has a fault condition.

Abstract: A computer implemented method of automatically designing a secondary air system for a gas turbine engine. The method comprises: receiving a geometry model of at least a part of a gas turbine engine, the geometry model including a plurality of data entities for a plurality of features of the gas turbine engine; defining a plurality of cavities using the plurality of data entities of the geometry model; determining a subset of cavities of the plurality of cavities that define at least a part of the secondary air system; and generating a secondary air system model from the determined subset of cavities that define at least a part of the second airflow system.

Abstract: An apparatus for controlling flow of coolant into an inter-stage cavity of a turbomachine is described. The cavity is bounded by a first turbine stage, a second turbine stage axially displaced along a common axis of rotation with the first turbine stage, and an annular platform bridging a space between the axially displaced first and second turbine stages. An annular plenum chamber is arranged inboard of the annular platform, the annular plenum chamber having one or more inlets for receiving coolant and one or more outlets exiting into the cavity, whereby, in use, coolant is delivered into the cavity at an increased pressure compared to coolant entering the plenum chamber at the inlet. The apparatus is beneficially arranged immediately upstream (with respect to the flow of a working fluid through the turbomachine) of an inter-stage seal assembly.

Abstract: Method of operating an engine and electricity generator powered by torque from the engine is provided. The engine has a working-line which is a locus of engine operating points as the engine is throttled. The method includes increasing electrical-load on the generator.

Abstract: A turbomachinery control system for controlling supercritical working fluid turbomachinery. The control system includes a light emitter to project light through working fluid of the turbomachinery toward a primary light detector provided within a line of sight to the emitter. The system further includes one or more secondary light detectors spaced from the line of sight, and a controller determining one or both of an intensity of light detected by the primary detector relative to the detected light intensity by the secondary detector, and wavelength of light detected by the primary detector relative to wavelength of light detected by the secondary detector. The controller determines the working fluid proximity of the critical point based on one or both of the determined relative intensity and determined relative wavelength, and controlling an actuator to control turbomachinery inlet or outlet conditions in accordance with the working fluid determined proximity of the critical point.

Abstract: An encapsulant composition comprises a silica containing inorganic-organic nano-hybrid matrix, particles of refractory ceramics suspended in the inorganic-organic nano-hybrid matrix, and, optionally, glass or ceramic fibres. The encapsulant may also contain ceramic coated metallic particles, and in some embodiments, a solvent or binder. The formulations can include a solvent, which may be removed during a curing process, or may be solvent-less.

Abstract: The present invention provides a gimbal expansion joint for use in joining ducting. The gimbal expansion joint has a first clevis adapted to be secured to one end of a first piece of ducting, a second clevis adapted to be secured to an end of a second piece of ducting, and a gimbal arrangement to which the first and second devises are pivotably connected to form a universal joint between the ends of the pieces of ducting. The joint further has a flexible duct extending between the first and second clevises to form a passage for fluid communication between the ends of the first and second pieces of ducting. The flexible duct has a respective flange at each end. Each flange provides an axially-directed face across which a clamping load is applied to affix the flange to a corresponding axially-directed face of the respective clevis.

Abstract: A method of assembling an annular combustion chamber assembly comprises positioning a plurality of first combustion chamber segments circumferentially side by side to form an annulus and removably securing the downstream end of each first combustion chamber segment to a first ring to form a first assembly. The method comprises positioning a plurality of second combustion chamber segments circumferentially side by side to form an annulus, removably securing the downstream end of each second combustion chamber segment to a second ring to form a second assembly. The method comprises removably securing the upstream end of each second combustion chamber segment of the second assembly to an annular upstream end wall. The method comprises inserting the second assembly into the first assembly and then removably securing the upstream end of each first combustion chamber segment of the first assembly to the annular upstream end wall to form the annular combustion chamber assembly.

Abstract: A tool and method for inserting an externally threaded object into a threaded receiving hole and removing and externally threaded object from the receiving hole. The tool is provided with an outer body that has a holding portion to hold the externally threaded object during insertion or removal. The holding portion may be a thread that corresponds with the thread of the externally threaded object. The tool also has a tightening body inside the outer body that has an engagement portion for engaging a corresponding engageable portion of the externally threaded body. The tightening body is rotated within the outer body to tighten or loosen the externally threaded body. During insertion or removal, the externally threaded body is securely held by the holding portion of the outer body.

Abstract: A row of aerofoil members for an axial compressor, the row comprises a circumferentially extending endwall and a plurality of aerofoils extending radially from the endwall. The endwall is profiled to include an acceleration region and a deceleration region in a location that corresponds to a position of peak fluid pressure. The acceleration region is provided upstream of the deceleration region such that fluid flow through the compressor and adjacent the endwall is accelerated and then decelerated so as to reduce the peak fluid pressure.

Abstract: A nacelle for a turbofan gas turbine engine is provided. An inner wall of the nacelle defines an air intake which directs air into the fan section of the engine. The intake has, in flow series, an intake lip, a throat and a diffuser. The diffuser has, in flow series, first and second flow conditioning sections over both of which the flow cross-sectional area of the diffuser increases with increasing downstream distance from the throat. In addition, over the second section the nacelle inner wall lies substantially on a surface of an oblique circular cone having an apex which is offset from the centerline of the engine.

Abstract: A method of modulating the cooling of a gas turbine component is disclosed. The method includes determining a target component temperature at which the gas turbine component can be maintained without the gas turbine component experiencing a failure over the course of an indicated life of the gas turbine component; scheduling a cooling air value to the target component temperature; and determining one or more of a demanded cooling air temperature and a demanded cooling air mass flow rate based on the scheduled cooling air value.

Abstract: A friction welding tool having a main body and a first clamp for gripping a first weld component and a second clamp for gripping a second weld component, at least one of the clamps being movable with respect to the other to effect friction welding of the respective weld components. The friction welding tool includes a vibration damper arrangeable to absorb vibrations of the first weld component during the friction welding. The friction welding tool includes an anchor element arranged to couple the damper to the main body of the friction welding tool to transfer absorbed vibrations to the main body.

Abstract: The remaining serviceable life of a critical rotating component of a gas turbine engine can be predicted using a remote detection component. The remote detection component is inspected to determine whether a crack has formed at a dedicated crack-initiation feature. If a crack has formed, a known correlation between the remote detection component and the critical rotating component is used to estimate the remaining serviceable life of the critical rotating component. Because the detection component is remote from the critical component, there is no risk of failure of the critical component.

Abstract: A gas turbine engine combustion chamber comprises upstream and downstream ring structures and a plurality of circumferentially arranged combustion chamber segments. Each segment extends the full length of the combustion chamber and each segment is secured to the upstream ring structure and is mounted on the downstream ring structure. The upstream end of each combustion chamber segment comprises a surface having a plurality of circumferentially spaced radially extending holes and the upstream ring structure having a plurality of circumferentially spaced holes extending radially through a portion abutting the surface of the upstream end of each combustion chamber segment. Each combustion chamber segment being removably secured to the upstream ring structure by a plurality of fasteners locatable in the holes in the combustion chamber segment and corresponding holes in the upstream ring structure.

Abstract: The present disclosure provides a rotary friction welding process including: providing an outer axisymmetric workpiece having a front first annular weld surface at a radially inward extent and a rear first annular weld surface at a radially inward extent; providing a front inner axisymmetric workpiece, the front inner workpiece having a front second annular weld surface at a radially outward extent of the front inner workpiece; providing a rear inner axisymmetric workpiece, the rear inner workpiece having a rear second annular weld surface at a radially outward extent of the rear inner workpiece; and rotary welding the workpieces together.

Abstract: A rotary friction welding process is provided, including: providing a first axisymmetric workpiece having a first annular weld surface, and a second axisymmetric workpiece having a second annular weld surface; and rotationally welding the workpeices. On the longitudinal section through the aligned workpieces, each of the first and second annular weld surfaces is flanked by radially inner and outer side surfaces, the first weld surface and its side surfaces being shaped to thermally match the second weld surface and its side surfaces across a line of initial contact of the first and second weld surfaces such the heat flows from the weld at all the side surfaces are substantially equal.

Abstract: Disclosed is a gas turbine engine comprising: a low pressure spool having a low pressure compressor and a low pressure turbine connected by a low pressure shaft; a reduction gear train having a sun gear, a carrier having a plurality of planet gears attached thereto, and a ring gear, wherein the sun gear is driveably connected to the low pressure shaft, and either of carrier and ring gear provides an output drive connected to a propulsive fan; wherein the connection between the low pressure shaft and the sun gear includes a flexible drive shaft having serially connected concentrically nested first and second input shafts between the low pressure shaft and sun gear.