Abstract: A method of fabricating or reparing a blisk (10) that comprises a plurality of blades (14) attached to the outer periphery of a disc (12). Blades (14) are formed separately from the disc (12) and are attached to stubs (13) on the disc (12) by friction welding. A metal powder, such as titanium, is sprayed onto the stubs (13) to reinforce them during the friction welding process. Once the stub (13) has been coated with the powder spray, plates (20) are fastened on the disc (12) between which the sprayed coating (18) is clamped. The plates (20) restrain the sprayed coating (18) to prevent delamination during friction welding. Once each of the blades (14) has been welded onto the respective stubs (13) the clamping plates (20) are removed and the sprayed coating (18) is machined away.

Abstract: In order to provide noise suppression, bumps or undulations are provided on a nozzle surface in order to vary the convergent-divergent ratio between that surface and an opposed nozzle surface. By such an approach, a circumferential variation in the shock cell pattern is created and the flow is deflected so as to enhance turbulent mixing thereby suppressing noise.

Abstract: A seal (48) between a compressor rotor blade (26) and compressor casing (28) comprises an abradable structure (59) on the compressor casing (28). The abradable structure (59) comprises a metallic foam (60) having pores (66, 68). The metallic foam (60) has a first a region (62) and a second region (64). The first region (62) of the metallic foam (60) is arranged adjacent to the compressor casing (28) and the second region (64) of the metallic foam (60) is spaced from the compressor casing (28) by the first region (62) of the metallic foam (60). The pores (68) of the second region (64) of the metallic foam (60) contain an abradable material (70) and the pores (66) of the first region (62) of the metallic foam (60) do not contain an abradable material.

Abstract: In order to accommodate loading in a number of situations such as with regard to thrusts in a gas turbine engine it is known to provide thrust bearings. These thrust bearings can be large and may be difficult to accommodate. By providing a duplex or multiplex thrust bearing which may be of increased axial length but reduced radial width easier accommodation may be achieved. By providing a thrust element 27 which compromises a balance beam from which extend elastic hinges to a mounting to a fixed bearing frame and ends of bearing races 21, 22 an appropriate thrust response can be achieved dependent upon bearing loads presented through bearing elements 23, 24. By rotation of the balance beam and flexing of the elastic hinges 30, 31, 32 an appropriate bearing load share is achieved.

Abstract: A solid oxide fuel cell component (12) comprises a plurality of solid oxide fuel cells (24) arranged in spaced apart relationship, and in electrical series, on a surface of the porous gas permeable support structure (16). Each solid oxide fuel cell (24) comprises a dense gas tight electrolyte member (28), a porous gas permeable first electrode (26) and a porous gas permeable second electrode (30). Each electrolyte (28) is arranged in contact with a corresponding one of the first electrodes (26), each second electrode (30) is arranged in contact with a corresponding one of the electrolytes (28). Each of the first electrodes (26) is arranged in contact with the surface of the support structure (16). The interconnectors (32), the peripheral seal layer (34) and the electrolytes (28) are arranged to encapsulate all of the first electrodes (26) except for the surfaces of the first electrodes (26) in contact with the surface of the support structure (16) to prevent leakage of reactant from the first electrodes (16).

Abstract: A blade member is oscillated in the direction of arrow A-A relative to a rim of a disc; a forge force is applied radially and a weld is formed along line; the blade member is formed from a face centred cubic (FCC) nickel based single crystal alloy, such as CMSX-4 of Cannon-Muskegon Corporation; the orientation of the single crystal blade member is controlled to maximize the stress on the slip plane; by maximizing the stress on the slip plane the in-plane friction forces and the forge force are minimized; minimizing the in-plane forces enables the single crystal blade member to be successfully welded to the rim of the disc.

Abstract: Acoustic noise from relatively high pressure gas flows as a result of opening for example a bypass valve in a gas turbine engine can cause problems. By provision of an acoustic apparatus incorporating an inner chamber where there is a pressure reduction and then a chamber divider surface incorporating small apertures with a wide spacing distribution an upward shift in acoustic frequency of the gas flow is achieved beyond normal human comprehension. An outer chamber is provided to receive the fine gas flow jets from the apertures in the chamber divider surface for further pressure reduction and low pressure release through wider apertures in an exit surface.

Abstract: An open-rotor gas turbine engine comprising a starter/generator, a first spool and a second spool, the second spool is of a lower pressure than the first spool; wherein the starter/generator is connected to the first and second spools via first and second clutches respectively. The method of operating the open-rotor engine comprises the step of supplying power to the starter/generator to drive the first spool via the first clutch to start the engine and, once the engine is self-propelling, a step of driving the starter/generator from the second spool via the second clutch to generate electricity.

Abstract: A method of pre-stressing a component such as a turbine blade (52) comprises providing an electrically conducting sheet (66) adjacent to a component (52) within a fluid medium (56). An electrical discharge is supplied from an electrical discharge circuit (58) to the electrically conducting sheet (66) to produce vaporisation there of (66). The vaporisation of the electrically conducting sheet (66) produces a planar pressure pulse in the medium (56) adjacent to the component (52). The planar pressure pulse impacts on a surface of the component (52) to produce a region of residual compressive stress within the component (52).

Abstract: A method of monitoring the health of a gas turbine engine of at least a pair of engines of an aircraft for example. The method comprising the steps of: a) obtaining steady state readings from predetermined sensors on the engines; b) calculate a percentage difference of the steady state readings from a unique engine linear synthesis model for each engine; c) compare the difference between the percentage differences for each engine and d) where this difference exceeds a predetermined value issue a warning as to an engine health problem. Maintenance of the engine can therefore be advantageously scheduled.

Abstract: A vane for a gas turbine engine comprising a cap arrangement comprising a cap insert and a cap adapted to receive the insert, the cap insert comprising a wall defining a through passage from top to bottom of the cap insert for receiving a cable or the like therethrough, the wall comprising a slot with a convoluted profile. Also a vane for a gas turbine engine comprising a cap and a cap insert as described.

Abstract: A method of operating a blade pitch change system of a gas turbine engine and its arrangement, the system comprising a blade, an actuator, a pressurised fluid system and a control system that regulates pressurised fluid to the actuator to control its position and thereby the blade's pitch; the blade pitch change system operates in a forward thrust mode and a reverse thrust mode, the control system comprises a main pitch control valve and a first reverse blade control valve through which the pressurised fluid passes. The method comprises the steps of a) continuously varying the main control valve to change the blade's pitch within the forward thrust mode at a first rotational rate, b) switching the first reverse blade control valve on to change the blades' pitch between the forward thrust mode and the reverse thrust mode at a second rotational rate that is greater than the first rotational rate.

Abstract: A fail-safe electromagnetic linkage has a support device for a valve head, and an actuator component actuable by an actuator. The support device is coupled to the actuator component whilst power is supplied to the electromagnet and decoupled from the actuator component whilst power is not supplied to the electromagnet. The assembly further comprises a return mechanism configured to drive the support device relative to the actuator component if power is not supplied to the electromagnet.

Abstract: In order to create titanium components with a titanium composite insert, a method is provided whereby an initial pre form 1 has a groove 2 formed in it. An encapsulating member 4 is then provided about the groove 2 in order to create a cavity 5 which is filled with titanium alloy powder 6. This titanium alloy powder 6 is densified and then accurately machined in order to create a groove insert form 7 which can accommodate a titanium composite material pre form insert 8 and further titanium alloy powder 9 such that through a high temperature isostatic pressing (HIP) process, the insert 8 is embedded. The original component form 1 can then be machined in order to create the final component elements such as aerofoils 13.

Abstract: Assembly of segmented seals can be problematic in areas of limited space for an introductory tapered mandrel and where there are the problems with damage to the seal surfaces 23, 24. By the present method and arrangement, a seal formed from segments 22 is expanded to an expanded state and then retained at that state by the use of a sacrificial material 26 in the gaps 25 between the segments 22 opened by expansion. The sacrificial material 26 is typically a low melting temperature wax and so is removed when the seal arrangement reaches its operating temperature.

Abstract: A method of fixturing a plurality of dissimilar blade assemblies, wherein each assembly undergoes one or more manufacturing steps to bring it to a finished form, the method comprising the step of providing on each of the articles a datum feature, wherein each datum feature is of identical form and dimension, in turn a) locating the datum feature of a first one of the articles in a complimentary fixture to secure the dissimilar article, b) performing at least one manufacturing step on the secured dissimilar article, c) removing the dissimilar article from the fixture, d) locating the datum feature of another of the articles in the complimentary fixture to secure the dissimilar article, e) performing at least one manufacturing step on the secured dissimilar article, f) removing the dissimilar article from the fixture.

Abstract: A gas turbine engine has a signal transmission system comprising a waveguide 40 which enables the transmission of microwave radio signals between a rotor 24 and stationary receiving electronics 32 of the engine. The waveguide 40 is centred on the engine axis 9.

Abstract: A engine such as a gas turbine engine has a bladed rotor 24 having variable pitch blades 8. In normal operation, the pitch angle of the blades 8 is controlled by a primary pitch control system. A back-up system is provided for controlling the blades 8, for example to displace them to a feathered condition, in the event of failure of the primary pitch control system. The back-up system comprises a pump 32 mounted on the rotor 24, and driven by relative rotation between the rotor 24 and a contra-rotating rotor 23. In response to a failure signal on a conduit 48, the pump delivers hydraulic fluid under pressure to a secondary actuator 30, which acts on the blade 8.

Abstract: A solid oxide fuel cell component (12) comprises a plurality of solid oxide fuel cells (24) arranged in spaced apart relationship, and in electrical series, on a surface of the porous gas permeable support structure (16). Each solid oxide fuel cell (24) comprises a dense gas tight electrolyte member (28), a porous gas permeable first electrode (26) and a porous gas permeable second electrode (30). Each electrolyte (28) is arranged in contact with a corresponding one of the first electrodes (26), each second electrode (30) is arranged in contact with a corresponding one of the electrolytes (28). Each of the first electrodes (26) is arranged in contact with the surface of the support structure (16). The interconnectors (32), the peripheral seal layer (34) and the electrolytes (28) are arranged to encapsulate all of the first electrodes (26) except for the surfaces of the first electrodes (26) in contact with the surface of the support structure (16) to prevent leakage of reactant from the first electrodes (16).

Abstract: A method of forming a fully consolidated joint between first and second components comprising the steps of forming a slot in the first component; inserting at least part of the second component into the slot; inserting a powder material into the slot; heating the powder material to form a pressure tight skin; and applying hot isostatic pressure to the pressure tight skin to form a fully consolidated joint. Also a method of repairing a component.