Abstract: A coated turbine engine article having a first wall and a second wall, wherein the first wall has a shielding feature integral with the article and which inhibits entry of a coating material into an open passage extending between the first wall and the second wall when the coating material is directed towards the article using a line of sight process.

Abstract: A mounting assembly for mounting two generally parallel pipes in close proximity to each other and to an adjacent surface. The assembly is so arranged that the pipes are permitted a limited degree of freedom of movement in an axial direction. Additionally, the assembly is so arranged that the pipes may be readily secured and released therefrom.

Abstract: A method of growing a single crystal seed bar (10) in which a mould provided with a grain selector filter (16) above a starter chamber is filled with molten metal, whereupon the metal is allowed to solidify slowly upwardly from the starter chamber. The filter (16) is provided with a pattern of openings, with the diameter of the openings being at least as large as the primary dendrite tip radius of the metal, but smaller than half the primary dendrite arm spacing.

Abstract: A control system provides an aggregate driven quantity demand signal for controlling an actuatable component. The system has a summing junction which generates the aggregate driven quantity demand signal by summing a first output signal, which converges on a steady state driven quantity requirement value, and a change in driven quantity demand signal. The system further has a feedback loop which generates the first output signal in response to the aggregate driven quantity demand signal. The system also has a first variable gain which tunes the change in driven quantity demand signal in response to a reference demand signal. The feedback loop includes a second variable gain which tunes the rate at which the first output signal converges on the steady state driven quantity requirement value. Typically, the reference demand signal corresponds to a desired value or desired change in value of a parameter which is itself varied or controlled by actuation of the actuatable component.

Abstract: A fuel injection system is provided for a gas turbine, comprising a mains airblast fuel injector having an annular shape, and inner and outer mains swirlers for swirling air past the mains airblast fuel injector. The inner and outer mains swirlers are concentric with the mains airblast fuel injector and are located radially inwardly and radially outwardly of the mains airblast fuel injector, respectively. The mains airblast fuel injector and the inner and outer mains swirlers are so arranged as to produce a fuel spray stream which expands from the mains airblast fuel injector and has a double flame front. The double flame front comprises flame fronts on both the radially inner and radially outer surfaces of the fuel spray stream.

Abstract: A fan blade comprises a root portion and an aerofoil portion. The aerofoil portion has a leading edge, a trailing edge and a tip remote from the root portion. A concave pressure surface extends from the leading edge to the trailing edge and a convex suction surface extends from the leading edge to the trailing edge. A portion of the tip of the aerofoil portion between the leading edge and the trailing edge of the aerofoil portion is thinner than the remainder of the tip. The portion of the tip of the aerofoil portion is spaced from the leading edge and is spaced from the trailing edge. The portion of the tip of the aerofoil portion has a recess such that the portion of the tip of the aerofoil portion is thinner than the remainder of the tip. The recess is arranged on the concave pressure surface of the aerofoil portion. This reduces vibrations of the fan blade.

Abstract: Noise control with respect to rotating machinery such as gas turbine engines is important to meet acceptable operational and environmental constraints. Buzz-saw noise in particular is due to differences in blade to blade geometries both as assembled and due to blade manufacturing tolerance variations. Generally, a plurality of blades rotate within a duct and some noise propagates forwards of the blade assembly. In order to abate such noise an acoustic lining is provided. By consideration of the acoustic attenuation effects of that lining, it is possible to rearrange the blades within the blade assembly such that the overall noise attenuation effects are improved.

Abstract: It is known that power is normally extracted within a gas turbine engine from a shaft in order to drive auxiliary devices such as electrical power generators. With high extraction rates from such shafts there is mismatching in rotational speeds between the shafts which must be adjusted through leakage taken from valves 8, 9. By measuring parameters and in particular pressure at a number of positions or parts within an engine arrangement 1 and comparing those parameters either through ratios or directly with reference values a controller can be configured in order to choose the correct sequence and scheduling of the valves 8, 9 opening to balance shaft speed. In such circumstances more efficient operation of the engine arrangement can be achieved over a wider range of engine speeds including idling.

Abstract: An alternating current system 10 has a primary circuit 11 which forms a primary winding 18 on a core 16. A secondary winding 24 is connected with a current source 26 or, alternatively, with an impedance 60. The core 16 is threaded by a superconducting coil 20 having a current source 22. In normal use, current in the coil 20 provides a DC bias level of flux in the core 16, and the source 26 is varied to maintain substantially constant flux, thereby minimizing losses in the primary circuit 11. In fault conditions, current in the coil 20 is reduced or removed to increase voltage losses across the coil 18, thereby limiting fault current. The impedance 60 can also be switched into circuit, creating further current limiting by virtue of the transformer effect of the windings 18, 24.

Abstract: A cooling arrangement 21 for use within a gas turbine engine comprises a first shroud or platform 26 incorporating coolant passages 25 and a second shroud or platform 28. Generally, each platform or shroud 26, 28 will incorporate a pressure portion and a suction portion, with the pressure portion incorporating the coolant passages 25 through which the coolant flow 27 becomes incident on a surface 40 of the suction portion of the second shroud 28. The surface 40 is inclined or tapered towards the passage 25, such that there is limited direct impingement upon a front edge 39 of the surface 40. The coolant flow 27 thereby remains adjacent to the surface 40 for a longer period and so enhances cooling efficiency.

Abstract: Peening provides compression of component (6, 46, 56) surfaces in order to create residual surface compressions to resist crack propagation in components such as aerofoils. Previously peening techniques have had problems with respect to achieving adequate treatment depths, speed of treatment and with respect to effectiveness. By the present method arrangement an electrical conductor (1, 41, 51) in the form of a wire is subject to electrical pulses to cause evaporation and subsequent breakdown with high power ultrasound (HPU) propagation in a volume of dielectric fluid towards a component and so peening. The electrical conductor (1, 41, 51) ensures that there is limited possibility of electrical discharge to the component (6, 46, 51) surface whilst the positioning of the wire (1, 41, 51) relative to the surface can be adjusted to achieve best effect particularly if reflector (5) devices are utilised to concentrate (HPU) pulse presentation to the component (6, 46, 56).

Abstract: A fan rotor arrangement comprises a fan rotor (24) and a plurality of fan blades (26). Each fan blade (26) comprises a root portion (36) and an aerofoil portion (38). Each aerofoil portion (38) has a leading edge (44), a trailing edge (46) and a tip (48). Concave pressure surface (50) and convex suction surface (52) extend from the leading edge (44) to the trailing edge (46) of each aerofoil portion (38). An annular wall (54) surrounds the fan rotor (24) and fan blades (26) and an inner surface (56) of the annular wall (54) has a circumferentially extending groove (58). The circumferentially extending groove (58) is arranged axially, or chordally, between the leading edges (44) and the trailing edges (46) at the tips (48) of the aerofoil portions (38) of the fan blades (26).

Abstract: A combustor having an array of dilution holes it provided with an asymmetrically located trim port for injection a controlled volume of air into the combustor. The controlled volume mixes with fuel rich air near the combustor wall and improves the dilution of the combustion gases. The improved dilution reduces the formation of NOx.

Abstract: In a number of practical situations it is desirable to provide consistency with regard to a metering material presentation. For example, with regard to welding and shape metal deposition it is desirable to provide a homogenous vortex free cloud of gas shielding about a work piece prior to and subsequent to processing. Unfortunately, metering meshes are subject to distortion through thermal gradients. By providing a support matrix arrangement comprising a first planar member and a second planar member incorporating ribbon elements and deflector portions bilateral deflection in the plane of the metering mesh can be accommodated whilst outward buckling is avoided. In such circumstances there is consistency with regard to metering mesh presentation and therefore gas flow through shielding.

Abstract: With regard to gas turbine engines it is necessary to maintain clearance between a rotating blade assembly and a casing to maintain efficiency. Thermal expansion and other factors are transients mean it is advantageous to provide active adjustment. By utilisation of piezo electric pumps 51, 52 operable at relatively high predetermined temperatures with a piston 54 and a cylinder 53 to cause displacement of an actuator 58 rapid adjustment is achieved. The cylinder 53 is divided into a first volume 55 and a second volume 56 so that each piezo electric pump 51, 52 can pressurise one volume 55, 56. A pressure balance is created across the piston 54 in order to position the associated actuator 58. A vent valve 67 can be used to effectively suspend the pressure balance across the piston 54 between the volumes 55, 56 for rapid displacement.

Abstract: A turbine blade 29 for a gas turbine engine 10 having an axis 20, the turbine blade 29 comprising: an aerofoil 30 including a high pressure surface 36, a low pressure surface 34, a root portion 38 and a tip surface 40 extending transverse from the high and low pressure surfaces 36 and 34, the high and low pressure surfaces 36 and 34 curve from the root portion 38 to the tip surface 40 in a direction that is substantially tangential to the axis 20 of the engine 10; and an air leakage restricting member 32 on the tip surface 40, the air leakage restricting member 32 being configured to substantially prevent leakage of air over the tip surface 40.

Abstract: In a method of numerical modelling of the operation of a gas turbine engine, randomly chosen numerical modifications are made to values within the model, to represent a disturbance for triggering rotating stall. This results in a faster onset of rotating stall within the model, reducing the computational effort required to achieve this.

Abstract: A component can be formed by a hot isostatic pressing (HIP) process but it is necessary to reinforce intricate internal structures against collapse and deformation by the hot isostatic pressing process. The present method utilizes a low melting point salt or alloy reinforcement within the structure which can be released when molten through a drain from the internal structure. The reinforcement may be molten as a result of the hot isostatic process or through achieving a temperature with the component which causes the reinforcement to become molten but without damaging the component itself. The remaining parts of the reinforcement may be removed by use of a solvent or simple washing with a corrosive agent to remove any reinforcement debris.

Abstract: A compressor of a gas turbine engine comprises blades 2, 4 provided on blade platforms 8, 12 of a rotor. Stator vanes 20 lie between the blades 2, 4 and are connected to a vane support structure 22. Sealing rings 38 are secured to the vane support structure 22 to restrict air flow into stator wells 36 on each side of the vane support structure 22. The sealing rings 38 are made from a flexible material so that they deflect on installation of the vane support structure 22 in a direction radially inwards between the adjacent blade platforms 8, 12.

Abstract: Fuel control arrangements for gas turbine engines generally comprise an injector and a fuel control valve. Typically the fuel control valve is controlled in terms of fuel demand through fuel pressure presented to the valve. Fuel demand may vary and in such circumstances stagnation of fuel adjacent to the valve may cause degradation of the fuel and therefore spurious operational performance. By providing a dedicated working fluid, and typically hydraulic, pressure to the valve a variable aperture port can be displaced to alter the fuel flow configuration within the valve. In such circumstances different fuel valve conditions can be generated by altering the available area of aperture in the port to divert or present fuel to the injector between and across first or primary fuel paths and second or pilot fuel paths as required. Thus more flexibility with regard to fuel presentation to the injector is achieved as well as consistency with respect to avoiding fuel degradation as fuel demand varies.