Abstract: A new method of friction welding, particularly suitable for manufacturing BLISKS and BLUMS for gas turbine engine rotors, in which the disc or drum rotor is angularly reciprocated while the airfoil blades are pressed radially against the rotor circumference. A machine for carrying out the method has a workpiece holder and a counterbalancing member mounted for angular reciprocation and coupled together by torque transfer means to constitute a resonant system. In operation the machine is driven at or near its natural frequency of oscillation. The natural frequency can be tuned by adjusting the stiffness of the torque transfer means. The machine also includes a drive mechanism.

Abstract: A ducted fan gas turbine engine nacelle assembly comprises an aerodynamic nacelle within which is enclosed a ducted fan gas turbine engine. The nacelle includes an annular containment structure which surrounds the engine fan and fan casing to contain any detached fan blade or blade parts.

Abstract: Fuel for the combustion equipment of the engine of a vertical take off aircraft is supplied via pumps 50,24 through a metering valve 22, which is under the control of a digital electronic control unit (DECU) 10. A pressure drop regulator 30 and spill valve 32 ensure there is a constant pressure drop across the metering valve 22. To provide a rapid reduction in fuel output when the aircraft pilot slams shut his control lever 16 when he touches down after a vertical landing, and therefore prevent the aircraft from bouncing, the DECU 10 detects the sudden slamming closed of the lever 16, and opens a solenoid valve 60. Fuel now bleeds along line 58, and the input 54 of the regulator 30 sees an increased pressure drop determined by a potentiometer formed by two flow restricting orifices 56,62. The regulator 30 therefore opens the spill valve 32 giving the desired rapid reduction in fuel flow through the metering valve 22.

Abstract: A ducted fan gas turbine engine is provided with a fan casing provided with a portion adapted to provide fan blade containment in the event of fan blade failure. The containment portion comprises three layers: a wall adjacent the fan blades, a plurality off metallic tubes attached to the radially outer surface of the wall and a layer of strong woven fibrous containment material surrounding the metallic tubes.

Abstract: A gas turbine engine annular combustor has a bulkhead at its upstream end which is protected by an annular array of heatshield segments. The segments are spaced apart from the bulkhead by means of a plurality of flanges. Cooling air apertures provided in the bulkhead direct cooling air into the space between the heatshield and the bulkhead. A portion of the cooling air is directed on to the downstream face of heatshield by means of a plurality of radially extending slots disposed around a fuel nozzle aperture in the centre of each heatshield segment. The slots provide for unrestrained thermal expansion of the heatshield region immediately surrounding the fuel nozzle aperture, thereby to prevent excessive thermal hoop stresses developing in the heatshield during engine operation.

Abstract: A gas turbine engine is provided with turbine stators which have hollow aerofoils. The aerofoils are internally cooled by a flow of air the path of which is defined by walls. The wall has a curved deflector at its outer end which causes air to flow over the wall end and down the other side of the wall. An extension member ensures that the air does not break away from the surface of the wall and is preferably made from sheet metal so as to provide a light, easily made structure.

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: In an investment casting process including the known steps of injecting a molten wax into a die, allowing the wax to solidify, removing the die, investing the wax with ceramic, firing the ceramic and removing the wax so as to provide a ceramic mould, and casting a molten material into the mould, and apparatus including a ceramic core the shape and size of the cavity to be provided in the blade, a removable wax impression die surrounding and spaced from the core member so that the space between the die and the core member is the shape and size of the blade, there is provided a number of platinum chaplets adapted and arranged to support and locate the core in relation to the ceramic mould by point contact abutment with an adjacent mould surface.

Abstract: A multiplex protective MCrAlY-based coating system for an M-based superalloy base material, where M is at least one of iron, cobalt and nickel, has a surface layer containing aluminides of platinum and the M constituent of the coating. There may be a single surface layer (FIG. 2) containing platinum modified aluminide, or alternatively a double surface layer (FIG. 3) in the form of a top layer containing platinum modified aluminide and a sub-surface layer containing aluminides substantially without platinum modification. The surface layer may also have extra chromium in solid solution in the M constituent of the coating, the chromium content in the surface layer of the coating being not more than about 40 wt. %, preferably 35 to 40 wt. %. The process for production of such a system involves deposition of an MCrAlY coating, optionally chrimizing it, and then aluminising and platinising it using appropriate amounts of platinum and appropriate heat treatments to obtain the desired variant of the coating system.

Abstract: A gas turbine engine nacelle assembly (10) comprises a pylon (13) for mounting the assembly on an aircraft, a nacelle (11) and a gas turbine engine (12) enclosed within the nacelle (11). Part (15) of the nacelle (11) is structurally integral with the pylon (13) and has the remainder of the nacelle (11) attached to it. The nacelle part (15) additionally provides at least partial support for the gas turbine engine (12). The arrangement provides weight savings.

Abstract: A vortex tube including an annular downstream scavenge duct is provided with a number of occluding members spaced circumferentially around the upstream entrance to the scavenge duct so as to restrict the entrance area of the duct. The occluding members are each generally triangular in section, are each attached to the wall of the vortex tube, and taper upstream from the entrance to the scavenge duct.

Abstract: The amount of fuel supplied by a low pressure pump and a high pressure pump to combustion means is controlled by a control unit. If most of the fuel delivered by the pumps is required by the engine a clutch engages to provide a direct mechanical drive between the pumps so that they are driven at the same speed. However if the combustion equipment requires a reduced flow of fuel the clutch disengages and the excess fuel is diverted by a valve to a turbine. The turbine drives the low pressure pump at a higher speed than the speed of the high pressure pump. The energy of the diverted fuel is converted to mechanical energy to drive the turbine so that the temperature rise of the diverted fuel is reduced.

Abstract: In a brush seal adapted for use in disturbed fluid flow conditions the upstream side-plate is formed of porous material or has foraminate region. In conventional seals disturbed flow can generate a flow adjacent the face of the seal bristle pack which tends to lift bristles away from the second sealing element. Seal leakage is consequently increased. The foraminate or porous upstream side-plate reduces disturbing forces on the bristles by modifying flow patterns to avoid forces which lift the bristles.

Abstract: A control mechanism for the thrust reverser of an aircraft comprises an open ended conduit, the open end of which operationally protrudes into the airflow over the surface of the aircraft. The airflow over the aircraft creates a partial vacuum within the conduit. A piston is translatable within a cylinder in accordance with the magnitude of the partial vacuum. The position of the piston within the cylinder determines whether the thrust reverser can or cannot be actuated, thereby preventing inadvertent in-flight thrust reverser actuation.

Abstract: Holding means for a component in a friction welding operation consists of a hollow cassette which is open at one end. The component is inserted into the cassette through an aperture at the open end that is shaped to frictionally engage a thickened portion of the component with a force greater than forces transmitted to the component during a friction welding operation. The component is pressed into the cassette to a predetermined depth so that a portion of it protrudes and forms the weld interface. Material upset during the welding operation may be sheared by increasing the weld generating force to overcome the frictional holding force so the end face passes over the weld region.

Abstract: A gas turbine engine combustor (16) is provided with an airspray fuel injector (24), the downstream end of which is coplanar with a heat shield (38) provided at the upstream end of the combustor (16). The fuel injector (24) injects a fuel and air mixture into the combustion chamber (16a) defined within the combustor (16) which is in the form of a cone having an angle greater than 130.degree.. The combustor (16) has enhanced weak extinction characteristics.

Abstract: A component holder for a friction welding apparatus has upper and lower clamp members which can be urged towards each other in order to clamp between them a component to which second or further components are to be friction welded. The first component is held in the component holder substantially entirely by friction clamping forces. The component holder is particularly suited to use with friction welding apparatus in which the component holder is carried by an angularly reciprocable workpiece mounting member.

Abstract: A solid oxide fuel cell stack comprises a plurality of first modules and a plurality of second modules stacked alternately. Each first module comprises a first distribution member which defines internal passages for the supply of a first reactant to the fuel cells. The first distribution member is enclosed by a porous support structure which carries the fuel cells on its two parallel surfaces. A plurality of passages are defined between the porous support structure and the first distribution member which distribute and remove the first reactant from the anodes. Each second module comprises a second distribution member which defines internal passages for the supply of a second reactant to the fuel cells. The passages in the first distribution member contain a catalyst for steam reforming the fuel. The catalyst is in intimate thermal contact with the fuel cells. Additionally a low temperature adiabatic preformer supplied with hydrocarbon fuel prereforms the fuel and supplies it to the passages.

Abstract: A stack of titanium sheets are placed on a worktable in a vacuum chamber. One of the mating surfaces of each pair of mating surfaces has had a stop off material applied in a desired pattern to prevent diffusion bonding. A pump evacuates the vacuum chamber and heaters heat the stack to evaporate volatile binder from the stop off. When all the binder has been removed the worktable is moved relative to an electron beam from a gun to weld the edges of the sheets together to form a sealed assembly. The volatile binder is removed quickly and oxidation of the titanium is prevented during baking out of the binder. The sealed assembly is then heated and externally pressurised to diffusion bond the sheets together. The integral structure is then heated and internally pressured to superplastically form one of the sheets to produce an article of predetermined shape.

Abstract: Overrich regions of fuel mixture in the combustion chamber of a gas turbine engine are dispersed by a jet of air directed into the region. Plumes of fuel/air mixture from adjacent airspray burners overlap to create overrich regions which tend to produce soot. Aligned apertures in the head of the combustion chamber direct jets of high pressure air at the regions with as little loss of momentum as possible, to disperse them. The apertures may be in the form of slots to provide fan-shaped jets.