Abstract: A broach tool comprises a very stiff backing member and has an arbor adapted to be received into the hollow spindle of a machine tool, for example a multi-axis, computer controlled machining center. The backing member carries a plurality of cutting points disposed to perform successive cutting operations as the broach tool is pushed through a workpiece by relative movement of a worktable and the machine spindle. The broach tool is formed with externally extending passageways to supply coolant to the cutting points. The coolant may be supplied through the machine spindle.

Abstract: A clamp for clamping a workpiece such as a forging of an aerofoil component comprises a support body 24 to which a clamping member 26 is hinged. The clamping member 26 has a workpiece clamping element 54 having pads 58 for engagement with the workpiece. The workpiece clamping element 54 is pivotable relatively to the clamping member 26 by means of a ball and socket connection including a ball element 40. This enables the workpiece clamping element 54 to self-align with the profile of the workpiece, for example with a surface of the blade 6 of the aerofoil component. In an alterative embodiment, the workpiece clamping element 54 is formed integrally with the clamping member 26, but is connected thereto by a necked region of the clamping member 26 which permits flexure of the workpiece clamping element 54 relatively to the clamping member 26.

Abstract: An air cooled guide vane (20) is provided with a stack of ducts (40) each of which converges towards its outlet end. Air flow turbulators (42) are positioned in ducts (40) and pressure losses in the air flow brought about by flowing over the turbulators (42), is recovered by the constricting effect of the ducts (40).

Abstract: A hot forming die (10) has forming surfaces (16, 18) and the forming surfaces have a nickel oxide layer (20). A stop off material coating (22) builds up on the nickel oxide layer (20) in operation. A method of cleaning the forming surfaces (16, 18) of the hot forming die (10) includes washing the forming surfaces (16, 18) of the hot forming die (10) in water to remove the stop off material (22) without removing the nickel oxide layer (20) from the forming surfaces (16, 18). The forming surfaces (16, 18) may be soaked in water (26) and/or a jet (30) of pressurized water may be directed onto the forming surfaces (16, 18). The stop off material is quickly removed without damaging the forming surfaces (16, 18). The retention of the nickel oxide layer (20) improves the quality of the hot-formed articles and the interval between cleaning of the hot forming die (10) is increased.

Abstract: An aerofoil (39) for a gas turbine engine (10) includes one or more internal cooling passage (74,76) for receiving a flow of cooling fluid, and means (84,86,88,90) for inducing at least two vortices in cooling fluid flowing through each cooling passage. Fluid within the vortices has a radially outwards, screw-type motion. The two vortices produce effective cooling of the aerofoil, which may be an aerofoil of a turbine blade.

Abstract: Tip clearance apparatus for a gas turbine engine comprises a shroud ring having curved portions so as to allow eccentric offset and hence asymmetric movement of the shroud. The shroud ring is mounted within a guide also having corresponding curved portions and movement of the shroud ring is controlled by the use of sensors.

Abstract: A rotor (38) for a gas turbine engine (10) has a low emissivity surface finish, or high emissivity surface finish (44), on at least a portion of its surface (42) to reduce temperature differentials between an upper portion and a lower portion of the rotor (38). This reduces bowing of the rotor (38) to allow the gas turbine engine (10) to be started without harmful vibrations of the rotor (38).

Abstract: Methods and systems for fault diagnosis are described. The methods are in particular, although not necessarily exclusively, for the detection of faults in multi-component systems, typically power plant, whose performance is characterised by a series of indirectly measurable performance parameters. The methods proposed are based on “optimisation techniques”, involving the optimisation of an objective function to obtain an estimate of performance parameters and operating parameters. In one aspect, a method is proposed that takes account of measurement biases. In another aspect, a method for optimising an objective function is proposed, which adopts a unique Evolution Program approach in which a population of possible solutions is sub-divided into a number of groups.

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 injections apertures (62,64,76,98) spaced apart in the direction of flow through the fuel and air mixing ducts (54,70,92). The apertures (62,64,76,98) 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: In one aspect the invention provides a friction welded component and a method of manufacture for such a component, comprising friction welding a reinforcement element (10) at an end cross-section thereof to a surface of a thin walled member (12) with an interlayer member (14) interposed between the reinforcement element and the surface of the thin walled member. The thin walled member and/or the interlayer are preferably of the same or similar material and the thickness of the thin walled member is preferably less than or equal to 6 mm and more preferably in the range 0.5 to 2 mm with the diameter of the reinforcement element being greater than 10 times the thickness of the thin walled member. The invention finds particular application in the fabrication of bosses to gas turbine aero-engine casings and fabricated nozzle components, for example.

Abstract: Where gas turbine engine structure eg combustion equipment, is to be air impingement cooled, the surface which receives the air jets is so shaped as to produce boundary layer separation zones 34, 38 and 44 in the cooling air, as it spreads across the surface. Mixing of the boundary layer with the remainder of the air flow results, followed by the re-establishment of the boundary layer. The new boundary layer is cooler than the original layer and so provides more effective cooling.

Abstract: A gas turbine engine fan blade containment assembly (38) comprising a generally cylindrical, or frustoconical, metal casing (40) which has an inner surface (62), an outer surface (64), an upstream flange (42) and a downstream flange (52). The outer surface (62) of the metal casing (40) is provided with a pattern of blind apertures (66) which extend radially inwardly from the outer surface (62) of the metal casing (40) between the flanges (42,52). The fan blade containment has reduced weight of the metal casing (40) of the fan blade containment assembly (38) for a large diameter turbofan gas turbine engine (10) but has unimpaired stiffness and penetration resistance.

Abstract: A method of characterizing the vibration of a plurality of rotating blades (12), such as turbine blades in a gas turbine engine, includes the steps of providing a single strain gauge (16A) on a single one (12A) of the blades and providing either one or two tip timing probes (22A, 22B) on a casing surrounding the blades. The data from the strain gauge (16A) allows the vibration of the single blade (12A) to be fully characterized while the data from the tip timing probes (22A, 22B) allows the amplitudes or velocities of vibration of all the blades to be determined. The relationship between the data from the tip timing probes for the single blade (12A) and the stress data from the strain gauge may be established. This relationship may then be assumed to apply to all the blades, thus allowing the stresses induced in all the blades by the vibrations to be determined.

Abstract: A fuel system (10) comprises a tank (12), a pump (14), heat exchangers (16 & 18) and a filter (20) in series fluid flow relationship. A fuel metering unit (24) returns a proportion of the filtered fuel to the tank (12) and is controlled by the engine electronic control (30). The system (10) operates so that fluid is not returned to the tank (12) when a pressure differential of the order of 5 psi is detected across the fluid filter (20) and the temperature of the fluid is below 0° C. The fluid is not returned to the tank (12) for a period of time to reduce the flow of fluid passing through the heat exchangers (16 & 18). The reduced flow of fluid passing through the heat exchangers (16 & 18) is heated to a temperature sufficient to melt any solidified impurities blocking the fluid filter (20).

Abstract: The spiral heat exchanger (10) has a hot end (16) and a cold end (18) arranged at opposite ends of the heat exchanger (10). A first, relatively hot, fluid is supplied to the hot end (16) of the heat exchanger (10) and the first fluid is removed from the cold end (18) of the heat exchanger (10). The heat exchanger (10) comprises first and second metal sheets (12,14). Each metal sheet (12,14) has hot and cold edge portions (18,20) at the hot and cold ends (16,18) respectively of the heat exchanger (10). Both of the hot and cold edge portions (18) of the first metal sheet (12) are thinner and have a greater diameter than the remainder of the first metal sheet (12) such that both of the hot and cold edge portions (18) contact the hot and cold edge portions (20) of the second sheet (14). The hot and cold edge portions (18) of the first metal sheet are joined to the hot and cold edge portions (20) of the second metal sheet (14).

Abstract: A vane assembly 40 for use within a gas turbine engine has a main vane portion 42 with an internal cavity 44. A cavity insert 46 is located within the cavity 44, close to the wall 48 to define transpiration cooling paths. Cooling air leaves the insert 46 through apertures directed at the wall 48, to produce impingement cooling. The transpiration cooling paths are extended back to the trailing edge 66 by means of a fairing 54. The use of a fairing in addition to the insert allows more complicated cavity shapes to be filled.

Abstract: A rotor (38) for a gas turbine engine (10) has a low emissivity surface finish, or high emissivity surface finish (44), on at least a portion of its surface (42) to reduce temperature differentials between an upper portion and a lower portion of the rotor (38). This reduces bowing of the rotor (38) to allow the gas turbine engine (10) to be started without harmful vibrations of the rotor (38).

Abstract: A turbofan gas turbine engine (10) comprises a fan rotor (32) carrying a plurality of radially extending fan blades (34). A fan blade containment assembly (38) surrounds the fan blades (34) and the fan blade containment assembly (34) comprises a generally annular, or frustoconical, cross-section casing (52). At least one corrugated sheet metal ring surrounds the casing (52) wherein the corrugations extend with axial and/or circumferential components.

Abstract: An aerofoil (34) for a gas turbine engine is substantially solid, including a concave pressure surface (42) and a convex suction surface (40). The pressure surface (42) is provided with a projection in the form of an elongate fin (44) which extends in the radial direction of the aerofoil.

Abstract: A seal assembly for co-operation with a shaft comprising a seal member which, in use, in a first position, forms a seal against the shaft, a seal housing for retaining the seal member, means for applying a radially inward force to the seal member and means for applying a radially outward force to the seal member so that, when the means for applying a radially outwards force is operated, the seal member is dilated to a second position thereby enabling the seal assembly and the shaft to be fitted and disassembled in conventional manner, when the means for applying a radially outward force is removed the means for applying a radially inward force to the seal member returns the seal member to the first position.