Abstract: A spacing arrangement for a gas turbine engine 10. The spacing arrangement being arranged such that as a rotor blade 26 of a compressor 13 rotates, the rotor disc 28 will move outwards and forwards to maintain a substantially constant gap 36 between the rotor blade 26 and an inclined casing 20.

Abstract: A gas turbine engine (10) comprises a second compressor (14), a first compressor (16), a heat exchanger (18), a combustor (20), a first turbine (22), a second turbine (24) and a third turbine (26) arranged in flow series. The first turbine (22) is arranged to drive the first compressor (16). The second turbine (24) is arranged to drive the second compressor (14). There are means to inject liquid into the gas turbine engine (10). The means to inject liquid is arranged to inject liquid upstream (46) of the second compressor (14), within (48) the second compressor (14), between (50) the second compressor (14) and the first compressor (16), within (52) the first compressor (16), between (54) the first compressor (16) and the heat exchanger (18) or within (56) the combustor (20) to boost the power of the gas turbine engine (10).

Abstract: In one aspect of the invention a method of manufacturing a thin wall isogrid or the like casing (10) by a machining process comprises the steps of mating a casing (10) with a support (20); the said support having a substantially continuous support surface (22) engaging at least part of the inner or outer surface of the casing (10) and machining a plurality of recessed pockets (12) in the said inner or outer surface of the casing (10) opposite the surface engaged by the said support (20). The support (20) reacts loads acting on the casing (10) by a machining tool (52,54) during machining, thereby minimising distortion of the casing (10) and tearing of the pockets (12) being formed. During the mating process, the casing (10) is deformed such that the support surface (22) engages substantially the whole of the inner or outer surface of the casing (10).

Abstract: A load absorption arrangement 40 for absorbing loads in a variable stator vane positioning system of a gas turbine engine includes a release means 42 which has a first operating condition to enable the load absorption arrangement 40 to transmit load, and a second operating condition, which is operable above a predetermined load, in which the release means 42 can release to enable the load absorption arrangement 40 to absorb the load thereon. The arrangement 40 is particularly suitable for absorbing shock loads which may arise under engine surge.

Abstract: With an active magnetic bearing 1 there is a limit to the available rapidity of response to transient loadings upon a target or rotor 4. Thus, in accordance with the present invention, storage devices 25, 125, 225, 35 hold an electrical voltage VS significantly greater than the normal supply voltage V provided by a normal electrical source 22, 32. In such circumstances when a very large transient loading is detected on the bearing 1 a switch 26, 37 discharges the supply voltage VS across the coil 23, 33 in order that a more rapid increase and higher value inductance current IT is presented to the coil 22, 32 in response to that variable loading upon the target/rotor 24, 34. The electrical discharge from the storage device 25, 125, 225, 35 can be adjusted using the switch 26, 37 or mixing the storage devices 25, 125, 225, 35 as required for an appropriate discharge signal shape.

Abstract: A seal arrangement 32 between a turbine shroud seal segments 38,40 in a gas turbine engine. The arrangement 32 comprises facing slots 34, 36 provided respectively in the segments 38,40 with offset spaces 42, 44 provided between the segments 38,40. A strip 46 is cemented into the slot 36 such that the flow path 50 passes through the space 42, around the free end of the strip 46, and out through the offset space 44, thereby providing a longer flow path.

Abstract: A method of balancing a rotary device (12,14) for balanced rotational operation when connected to a drive shaft (24) by a flexible coupling (26,28). The method comprises the steps of connecting a drive shaft simulator (32,34) to a rotary device (12,14) and, rotating the said device (12,14) to simulate drive shaft unbalance due to misalignment of the rotary device (12,14) and the drive shaft (24) being simulated when the drive shaft (24) and rotary device (12,14) are connected together.

Abstract: A turbine engine arrangement is provided in which contra rotating shafts 104, 105 are respectively secured to a fan and a gearbox 106 which is also coupled to the shaft 104. In such circumstances the relative rotational speed ratio between the shafts 104, 105 can be determined with a first low pressure turbine 101 secured to the first shaft 104 arranged to rotate at a lower speed but provide high work whilst a second low pressure turbine 102 secured to the second shaft 105 rotates at a higher speed governed by the gearbox 106. By such an arrangement a smaller gearbox 106 may be used as less power is transferred through that gearbox 106 than with previous arrangements. By contra rotation of the turbines 101, 102 a lower flow deflection guide vane assembly 103 may be used and a further stator/guide vane assembly is not required between the turbines 101, 102.

Abstract: A three-stage lean burn combustion chamber (28) comprises a primary combustion zone (36), a secondary combustion zone (40) and a tertiary combustion zone (44). Each of the combustion zones (36, 40, 44) is supplied with premixed fuel and air by respective fuel and air mixing ducts (54, 70, 92). The fuel and air mixing ducts (54, 70, 92) have a plurality of air injection slots (62, 64, 76, 98) spaced apart transversely to the direction of flow through the fuel and air mixing ducts (54, 70, 92). The air injection slots (62, 64, 76, 98) extend in the direction of flow through the fuel and air mixing ducts (54, 70, 92) to the reduce the magnitude of the fluctuations in the fuel to air ratio of the fuel and air mixture supplied into the at least one combustion zone (36, 40, 44). This reduces the generation of harmful vibrations in the combustion chamber (28).

Abstract: A method of monitoring engine order forcing frequency comprises the steps of: selecting at least one engine order for an engine, the engine order being related in a known manner to one or more engine vibration responses generated by the forcing of the engine order; receiving measurement data which provide a measure of the change in the frequency of the or each vibration response as the engine speed varies, and calculating therefrom the change in the engine order forcing frequency; and determining, on the basis of the calculated change in the engine order forcing frequency, a corresponding change in at least one second engine order forcing frequency for the engine as the engine speed varies.

Abstract: A gas turbine engine rotor blade containment assembly (38) comprises a generally cylindrical, or frustoconical, metal casing (40). The metal casing (40) has at least one arched portion (62, 64, 66) and each arched portion (62, 64, 66) extends circumferentially around the metal casing (40). Each arched portion (62, 64, 66) comprises a radially inwardly extending arch (68) in which the trough (74) of the arch (68) is radially inwardly of a straight line (76) interconnecting the axial ends (70, 72) of the arch (68). The trough (74) of the arch (68) is radially inwardly of the at least one of the axial ends (70, 72) of the at least one arch (68). The arched portions (62, 64, 66) introduce compressive stresses into the metal casing (40) during a fan blade 34 impact and enable the metal casing (40) to withstand the impact. The fan blade containment assembly (38) is lighter for large diameter turbofan gas turbine engine (10).

Abstract: A casing arrangement (20) for surrounding a rotary component (16) of a gas turbine engine (10) is disclosed. The casing arrangement (20) comprises a casing member (22A), which is formed to extend at least partially around the component (16). The casing member (22A) defines a fluid flow path for the flow of a cooling fluid therethrough.

Abstract: A blisk for use in the turbine section of a gas turbine engine comprises a disk around the circumference of which is disposed a plurality of blades in an annular array. The blades are preferably cast separately and then joined, for example by welding, so that the roots form a continuous ring. The remaining volume of the rotor disk is formed of consolidated metal powder by a hot isostatic process. Extending a short distance above each blade root is a shank carrying a platform and the blade airfoil section. The dimensions of the platforms in the circumferential direction are such that they cooperate to form a plenum chamber encircling the periphery of the rotor disk. The blades are cast with internal cooling passages access to which is gained from the plenum through orifices in the sides of the blade shanks. Thus, in use, cooling air may be passed across at least one face of the blisk into the plenum from where it enters the blade cooling passages.

Abstract: Trailing edge coolant flow passages 100 are generally sized and determined by the available width 102 of the trailing edge. In such circumstances it may be difficult to achieve the desired flow control due to the limitations upon casting and moulding of narrow coolant passages within the constraints of that width 102. The present invention provides flow control features 103, 203 which act to reduce the available cross-sectional area and so provide for flow control and normally like for like reduction in such flow. It will be understood that coolant flow is essentially a parasitic effect upon engine performance, thus reduced coolant flow for desired operational performance has benefits. Due to the reinforcing effect of the flow control features 103, 203 it is possible to also provide wider than previously acceptable coolant flow passages within trailing edges with the reduction in available area provided by the flow control features 103, 203.

Abstract: A variable stator vane assembly 10 where two downwardly inclined engagement faces 30 are provided on the top of the stator vane upper stem 14, extending for part of the width thereof. A pair of projections 36 with inwardly inclined surfaces 38 are provided on the underside of the lever arm 16. The surfaces 38 are only engageable with the faces 30 in one axial alignment, and otherwise the lever arm 16 will be raised relative to the stator vane 12 to clearly indicate incorrect mounting thereon.

Abstract: A securing assembly comprises a first rotatable member (20) defining a first recess (36). The assembly also includes a second rotatable member (30) defining a second recess (46). The first recess (36) has an engagement formation (64). Securing means (58) are locatable in the first and second recesses (36, 46) for securing the first and second rotatable members (20, 30) to each other. An urging formation (60, 62) is provided on one or both of the securing means and the second rotatable member (30) for urging the securing means (58) into engagement with the engagement formation (64) when the first and second rotatable members (20, 30) are rotated.

Abstract: A three shaft ducted fan gas turbine engine (10) has a turbine system comprising a high pressure turbine rotor (32), an intermediate pressure turbine rotor (36) and first and second low pressure turbine rotors (42,44), that straddle intermediate pressure turbine rotor (36). Rotors (42,44) are mechanically connected by a casing (46) that bridges turbine rotor (36) so as to achieve transmission of torque from the first to the second thereof. Rotor (42) also delivers gas flow to the intermediate pressure rotor (36) at a much lower temperature than is experienced by conventional arrangements.

Abstract: A flow control arrangement (30; 50; 70) is described in which an inlet slot 35, 55, 85 is positioned prior to a stationary structure (33; 43; 53; 73; 83) such as a stator or pylon in order that air flow is bled or removed from a main flow 31, 51, 81. The removed air passes through a passage duct 36, 56 and is re-injected through an outlet nozzle 37, 57, 87 with an askew angle consistent with rotor blades 32, 52, 72, 82 of a turbine. In such circumstances, distortion in the flow due to the stationary structure 33, 43, 53, 83 is relieved such that there is less instability downstream from that structure 33, 43, 53, 83.

Abstract: An unshrouded rotor blade 24 comprising an aerofoil 28, said aerofoil 28 having a leading edge 34, a trailing edge 36, a pressure surface 30 and a suction surface 32, there being provided at a radially outer extremity of the aerofoil 28 a gutter 40 which is wider than the aerofoil 28 adjacent the trailing edge 36 thereof, wherein at least a part of the gutter 40 is offset towards the aerofoil pressure surface 30.

Abstract: The present invention relates to a cooling arrangement in which a fractal passage network is provided incorporating several passage stages. Each passage stage 4, 5, 6, 7 has substantially the same passage cross-section for consistency with other passage stages to facilitate flow pressure control across the fractal passage network. Normally, the length of passages in each passage stage are also specifically determined in order to achieve a consistent flow pressure control. The arrangement is particularly utilised with regard to cooling within turbine engine components such as blade aerofoils.