Abstract: In a gas turbine engine having a ceramic nozzle guide vane supported by a metal turbine casing the radially outer end of the vane is provided with opposed frustoconical sections which converge towards each other onto a middle cylindrical section. A metal split ring surrounds the cylindrical section, and the radially inner and outer ends of the ring abut the frustoconical sections. The split ring is provided with a flange which cooperates with a groove structure on the turbine casing, thus enclosing the split ring to the casing. A bolt means fastens together two sections of the casing either side of the vane, thereby holding the split ring against the vane. On increase in temperature the split ring expands more than does the vane. The ends of the split ring therefore slide against the frustoconical surfaces of the vane to take up the expansion, and in so doing maintain contact with the vane.

Abstract: A failure tolerant engine mounting is formed by three links between the engine and its support structure, one of the links being arranged so that in the event of failure of either of the other links it will form a connection between three points on the engine and supporting structure which are symmetrically arranged about a vertical axis through the engines center of gravity.

Abstract: The throttle fuel flow of an aircraft jet engine is controlled by measuring the actual value of an engine parameter demand and measuring the error between the actual value and a value of the parameter demand calculated from a number of engine operating data. The error is then used to drive an integrating fuel throttle value until the error is substantially zero. The engine parameter chosen is the high pressure compressor delivery mach number.

Abstract: The normally multi-part gas turbine engine labyrinth seal outer portion which carries an abradable lining, is formed from a single piece and has a groove machined in its periphery for the receipt of the feet of respective stator vanes. Pins are fitted in pairs through the walls of the groove to provide lateral location for the feet. The pins and a groove liner are made from an anti-frettage material.

Abstract: A gas turbine engine turbine aerofoil blade includes an aerofoil portion having pressure and suction flanks. The flanks are internally interconnected by wall member which cooperates with the flanks to define first and second cooling passage portions which are interconnected by a bend portion. The wall member is locally thickened adjacent the bend portion. In the second cooling passage portion the locally thickened wall member portion progressively increases in thickness towards at least one of the flanks so as to eliminate any acute angle between the flanks and the thickened wall member portion adjacent thereto.

Abstract: It is common practice to assemble heat exchangers from a multitude of pre-formed and sometimes extremely delicate pieces. The pieces have to be held in jigs along with appropriately placed braze material and then heated to achieve brazing. The invention takes advantage of the ability which some materials have to considerably extend their areas without rupturing by using such materials in that they are assembled in the flat condition and then diffusion bonded, followed by inflation of the parts of the assembly which are to provide the fluid passageways, inlet manifolds, and headers. The construction of heat exchangers is thus considerably simplified.

Abstract: A rail gun (10) comprising two elongate co-extensive rail electrodes (11,12) having confronting surfaces (17,18) which are of toothed cross-section configuration. The toothed configuration of the surfaces ensures that during the operation of the rail gun (10), there is not an electric current concentration in the vicinity of the confronting surfaces (17,18). Consequently problems associated with the overheating of the confronting surfaces (17,18) are reduced.

Abstract: In an accessory drive unit e.g. as used in a gas turbine engine, some of the gears in a gear train are provided with pockets 20 in which drainage oil is collected on engine shut down. On re-starting of the engine, the collected oil is acted upon by ribs 16 and is flung onto the teeth of the gears so as to provide immediate lubrication, rather than experience a delay until main lubricant supply pressure is increased. Friction and wear on start up is reduced.

Abstract: In an engine cooling system wherein supply pipes 40, 50 supply cooling fluid (e.g.: air) to the turbine 20 from a compressor bleed 10, upon failure of one of the supply pipes 50 the backflow of cooling fluid from the turbine to the point of failure may be stemmed by use of a vortex amplifier 140, 160 connected into each supply pipe 40, 50, the tangential ports of the vortex amplifiers being interconnected by a balance pipe 180. This allows the total minimum bleed flow rate of cooling fluid supplied to the turbine from the compressor bleed to be reduced.

Abstract: An aerofoil for a gas turbine engine turbine rotor blade or stator vane is subject to film cooling by multiple rows of small cooling air exit apertures in the exterior surface of the blade or vane. Each exit aperture is supplied with cooling air through at least two holes extending from the aperture through the wall of the blade or vane to interior chambers or passages. The holes are mutually intersecting and their intersection forms the exit apertures and defines a flow constriction for controlling the flow rate of cooling air through the holes and out of the aperture. If the holes' centerlines intersect behind the plane of the exterior surface by an optional distance, the flow constriction is spaced apart from the exit aperture and is within the wall thickness, the exit aperture being enlarged. These film cooling hole configurations reduce the liability of the holes to block up due to contamination by environmental debris.

Abstract: A compressor assembly (12,13) for a gas turbine engine (10) comprises a centrifugal compressor (12) having a variable cross-sectional area diffuser (13) located at its downstream end. When the cross-sectional area of the diffuser (13) is less than a maximum value, some of the air exhausted from the downstream end (24) of the compressor (12) is directed to the upstream end (23) thereof. Sufficient air is so directed as to ensure that the mean air velocity at the outlet (30) of the diffuser (13) remains substantially constant.

Abstract: An injector which is suitable for the injection of fuel and steam into the combustion apparatus of a gas turbine engine. The injector defines a substantially circular cross-section chamber having upstream and downstream ends through which steam operationally flows. Steam is supplied to the upstream end of the chamber in such a manner that it is urged into a vortex as it passes through the chamber. The downstream end of the chamber is outwardly flared so that the steam flow is exhausted from the injector in a genenrally conical configuration.

Abstract: In a gas turbine engine, a turbine blade vibration damper is located between the underside of a blade platform and a turbine disc, and comprises a member which extends axially parallel to the blade roots. The member has on its outer surface an inverted "V" shaped projection which engages a complementary shaped recess in the underside of the blade platforms. The member has two limbs of unequal length. Centrifugal forces on the longer limb rocks the member and urges the shorter limb into engagement with the disc rim.

Abstract: PTFE-loaded wax is used in the laser drilling of holes in hollow turbine blades to prevent strike-through of the beam to an opposite wall of a cavity in the blade. The PTFE-loaded wax is poured or injected in molten form into the cavity prior to laser-drilling, and is subsequently removed by steaming.

Abstract: A variable stator vane arrangement for an axial flow compressor comprises a plurality of stages of variable pitch stator vanes each of which is operated by a respective control ring. The vanes in each stage are connected to the control rings by operating levers. An axially extending member is connected to each control ring by operating links. The axially extending member is arranged in a plane substantially tangential to each control ring and is movable in the plane substantially tangential to the control rings to change the pitch of the variable pitch stator vanes. Hydraulic rams are provided to move the axially extending member. The hydraulic rams may be operated to give either proportional or non-proportional movement of the variable pitch stator vanes. A controller may use signals from position detectors positioned on the control rings or position detectors positioned on the hydraulic rams together with compressor parameters to control the pitch of the vanes.

Abstract: The low pressure turbine of a gas turbine engine has an array of rotor blades and a shroud which surrounds the blade tips. The shroud is made up of a plurality of segments which are pivotally mounted from the turbine casing at their midpoints. The upstream portions of the shroud segments are fixed to the casing so that localised cooling of the casing in the region of pivotal attachment of the shroud segments causes the shroud segments to tilt and thereby improve the gas seal between the tips of the rotor blades and the shroud segments.

Abstract: An apparatus for drilling a shaped hole in a workpiece by means of a laser beam emanating from a laser source, includes (a) means for directing the beam onto the workpiece, (b) means for controlling the angle of the beam striking the workpiece relative to the axis of the hole, and, (c) means for controlling the distance between the intersection of the beam with the surface of the workpiece and the axis of the hole, so that the combination of the means for controlling the angle and the means for controlling the distance enables a shaped hole to be drilled in the workpiece by the laser beam. The apparatus also includes means for rotating the direction of the beam about the axis of the hole so as to describe at least part of the curved surface of a one that has its vertex on or within the body of the workpiece.

Abstract: Known methods of melting Titanium and its alloys for the purpose of sheathing a ceramic filament include the premelting of the metal in a crucible. This method results in contamination of the metal. The present invention obviates the crucible and instead positions a rod of solid Titanium or an alloy thereof adjacent the filament and locally heats the end of the rod. The melt continuously coats the filament which is then traversed laterally of the rod. The method is employed in an inert atmosphere and contamination is thus avoided. In a preferred embodiment, a computer controls the rate of melting of the rod, the movement of the rod, and the lateral movement of the filament.

Abstract: A cooling air outlet duct for a heat exchanger of a gas turbine engine is provided with a rotatable wall portion. The rotatable wall portion is rotatable about a pivot positioned at its upstream end so that the total flow area between the downstream end of the rotatable wall portion and a first wall of the fluid outlet duct and the fluid flow rate may be varied to obtain relatively high exit velocities for the cooling air discharging from an exit nozzle in a fan casing to give good thrust recovery. This produces a lightweight and uncomplicated valve for the fluid outlet duct.

Abstract: A delicate or awkward to grip component which is to be friction bonded to another has formed on it a flange or like formation which can be gripped firmly by a wedging action. The component is loaded into a shuttle, provided with a releasable wedge clamp, which is carried by the output drive member of a friction bonding machine. Machine forces for the necessary friction heating and bonding phases of the operation are transmitted to component through faces on the shuttle which abut the component flange.