Abstract: A variable geometry pre-mixing fuel injector (50) for injecting a fuel/air mix in a downstream direction, comprising: an air inlet (60); a fuel inlet (58) positioned downstream of the air inlet (60); a duct (56) extending at least downstream of the fuel inlet (58) to define a fuel and air pre-mixing zone (62), that narrows to form an opening (64); and means for varying the flow of fuel/air mix from the pre-mixing zone (62) through the opening (64).

Abstract: An axial flow compressor (16) comprises a plurality of variable stator vanes (32) circumferentially spaced apart and extending radially. Each variable stator vane (32) is rotatably mounted on a compressor casing (28). A control ring (38) surrounds the compressor casing (28). Each variable stator vane (32) is connected to the control ring (38) by a respective one of a plurality of operating levers (40) and the control ring (38) is spaced from the compressor casing (28) by a clearance. A plurality of bimetallic strips (50) are arranged circumferentially and are positioned radially between the control ring (38) and the compressor casing (28) and the bimetallic strips (50) control the clearance between the control ring (38) and the compressor casing (28) whereby any error of the variable stator vane (32) angular position is reduced. Each bimetallic strip (50) extends radially outwardly from the compressor casing (28) towards the control ring (38).

Abstract: In order to couple coolant air flow presented through a coolant gallery 4, 24 through an opening 7, 27 into a passage 8, 28 a flow deflector 6, 26 is provided. The flow deflector 6, 26 progressively deflects the coolant air flow 5, 25 through the opening 7, 27 such that there is reduced loss in coolant flow 5, 25 pressure.

Abstract: A platform arrangement for components such as aerofoil vanes 1, 21 is provided whereby the necessary rigidity provided by the platform does not create excess problems with respect to stress and strain fatigue failure at thinner sections of the component. The leading edge 6, 26 and trailing edge 7, 27 of a vane generally have a thinner section and so when subject to greater flex deformation such flex deformation may lead to premature failure through stress and strain. Structural configurations are now provided which comprise cut out windows 24 in the platform 22 beneath the edges 26, 27 or alternatively differential material types at these locations with a less stiff nature.

Abstract: A pump control system (20) for a pump (21) in a gas turbine engine (10) is described. The pump control system (20) comprises demand means (22) for providing a demand signal (23) relating to a required rate of fluid flow and/or pressure from the pump (21). The system also comprises sensing means (26) to sense at least one parameter of fluid downstream of the pump (21) and to provide at least one feedback signal (28) relating to the, or each, respective parameter. Comparator means (30) is provided for comparing the demand signal (23) with the, or at least one, feedback signal to provide a control signal (33) for controlling the pump.

Abstract: A method of optimising a design of a component by conducting at least one analysis employing a 3D computer model which incorporates empirically obtained data values stored as 2D data sets. Ambiguities between values from different data sets which relate to common nodes, where the nodes define polygonal elements common to both 2D data sets, are resolved by determining an apparent area of said common polygonal elements from each of the at least two 2D datasets. The data value from the 2D dataset associated with the common polygonal element having the greater apparent area is used. An optimum component design is selected on the basis of the results of the analysis.

Abstract: A metal is used as a predominant component of an outermost metallic portion of a ceramic-containing and metal-containing vibration damping coating for a metallic article, for the purpose of enhancing resistance of the coating to foreign object damage and/or erosion while substantially maintaining or enhancing vibration damping performance of the coating. The outermost metallic portion is preferably substantially free of non-metallic intrusions and cavities.

Abstract: A method of optimising the design of a component is provided, in which a set of principal design variants is generated, the variants having design parameters which are common to all design variants of the set and some which differ between variants. Subsets of secondary design variants are generated by a computer executed rule based geometry engine, the subsets comprising at least one secondary design variant, generated by modifying at least one design parameter or design variable of the principal design variant.

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 seal arrangement, for example a brush seal 8? in a gas turbine engine, includes thermal matching means for matching the rates of response of a supporting ring 14?, 16? of the seal, and of a rotatable component 4 with which the seal cooperates, to thermal changes in the environment of the seal induced by changes in operating conditions. The thermal matching means may comprise a slugging mass 24 and/or thermal insulation 28. Alternatively, or in addition, the region 24 of the housing at which the seal 8? is mounted may be made from a relatively low thermal expansion material. These measures reduce the rate of expansion and contraction of the seal 8? as the temperature in the engine varies so as to match more closely the rate of expansion and contraction of a rotatable component with which the seal cooperates.

Abstract: A health monitoring apparatus for a mechanical system includes: a microphone arranged to receive sound from the system; and a processor adapted to process the output of the microphone. The mechanical system may be a gas turbine engine. Further, the engine may have a plurality of bleed valves, each of the bleed valves being configured such that, when open, it produces a sound which is distinguishable from the sounds produced by the other bleed valves, and the microphone being arranged to detect the sound from the bleed valves.

Abstract: A method of forming a turbine nozzle guide vane 2 for a gas turbine engine, the guide vane 2 comprising an internal cavity 14 and having internal features 16, comprises investment casting metal around a core member 30 that defines the internal cavity 14 and internal features 16 of the guide vane, removing the core member 30, and machining the guide vane 2. The process of investment casting around the core member 30 includes the step of casting at least one feature 40 external to the guide vane 2. The external feature 40 is used as a reference point to indicate the location of the internal features 16 of the guide vane 2 during the machining of the guide vane 2.

Abstract: An axial compressor has at least one circumferential row of aerofoil members (30a, 30b, 30c) in which at least one of the two end walls (37) between adjacent blades is given a non-axisymmetric profile, defined by circumferentially-extending sinusoids at a number of axial positions (AA, BB, CC). Corresponding points on the successive sinusoids are joined by spline curves, so that the curvature of the end wall is smooth. This end-wall profiling modifies the boundary layer flow at the wall, reducing or eliminating the corner separation and reversed flow associated with known arrangements.

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 laser drilling a gas turbine engine nozzle guide vane segment made up of two or more adjacent aerofoil sections spaced apart so that between each pair of aerofoil sections there are entry, throat and exit sections. The laser beam is directed at the surface of the aerofoil section to be drilled through either an entry or an exit section and a jet of assist gas is directed at the point of incidence of the laser beam through the other of the entry or exit sections.

Abstract: A gas turbine engine pre-diffuser 40 is generally annular, including radially inner and radially outer walls 40 and 42 and a generally cylindrical midline 48 defined between the walls. The pre-diffuser 40 includes a central member 46 which forces air flowing through the pre-diffuser 40 to separate, initially to be directed away from the midline 48 before subsequently being allowed to diffuse back towards the midline 48. The majority of the diffusion takes place on the walls of the central member and is thus in an inner region of the annulus of air ejected from the pre-diffuser to pass to the combustor. Any boundary losses therefore do not significantly effect air at the extremities of this annulus, this air being destined for the annuli of the combustor and requiring relatively high energy levels.

Abstract: A variable stator vane actuating lever (50) for use in a compressor (20) of a gas turbine engine (10). The lever (50) comprises a first end (52) for pivotal connection to a stator vane actuator ring (36) and a second end (54) for abutting a stator vane spindle (32). The stator vane spindle (32) has a diameter and flat positions (56,58,60,62). The second end (54) of the lever (50) has resilient members (64,66) for abutting the flat portions (56,58,60,62) of the stator vane spindle (32) at diametrically opposite locations. The resilient members (64,66) are integral with the second end (54) of the stator vane spindle (32) and are curved so that they are substantially tubular to provide even load distribution and improved location of the lever (50) on the stator vane spindle (32).

Abstract: A vane assembly for a gas turbine engine, the vane assembly comprising an aerodynamic main body across which gas can flow in streamlines, the main body defining a chamber and a plurality of cooling apertures extending through the main body, the cooling apertures being arranged in a plurality of arrays, wherein the vane assembly is arrangeable so that each array is generally parallel to the streamlines, and the vane assembly further including a baffle arrangement provided in the chamber the baffle arrangement having a gas deflection surface which extends across a plurality of the arrays.

Abstract: An exhaust nozzle assembly for a gas turbine engine, the assembly comprises a main axis, an inner nozzle, an outer nozzle, a translatable centre-body and an actuator for translating the centre-body between a forward position and a rearward position. The centre-body is disposed radially inwardly of the inner nozzle thereby partly defining an inner duct for a core engine gas flow, an outer duct for a bypass gas flow is defined by the inner nozzle and the outer nozzle. The outer nozzle extends downstream of the inner nozzle and with the centre-body defines a final mixing duct having a final exhaust exit area. When the centre-body is in the forward position the final exhaust exit area is at a maximum area, and when the centre-body is in a rearward position the final exhaust exit area is at a minimum area.

Abstract: A clip used to attach an acoustic panel to a fan casing of a gas turbine engine is “U” shaped. One arm of the clip is provided with spacing means cut into the material of the arm and which may be bent to define the spacing between the outer face of the arm and a support. Engagement means, which may also be cut into the material of the clip, may be bent to engage a recess in a tenon inserted into the receiving means.