Abstract: An acoustic lining for a flow duct has a first perforate skin fixed to an underlying sound-absorbing layer. The first perforate skin is overlain by a second perforate skin which forms the wall of the flow duct. One of the skins is relatively moveable in a sliding sense with respect to the other skin so as to vary the acoustic impedance of the duct wall as the perforations in the respective skins slide into and out of registration with each other. This enables the acoustic impedance of the duct wall to be varied to suit the flow and noise conditions prevailing in the duct and so obtain optimum noise attenuation in the duct, which may be the intake duct of a turbofan aeroengine.

Abstract: A gas turbine engine fuel burner comprises a convergent/divergent flow passage which receives a flow of swirling fuel and air upstream of the passage throat. The fuel and air mixture passes through the throat and is entrained into a further mass of swirling air which enters the passage through air swirlers in the wall of the divergent portion of the passage.The invention is intended to promote good fuel and air mixing, fine atomization and a reduction in carbon deposition on the burner.

Abstract: In a non-contacting gas seal between static and rotatable components of a gas turbine engine, a seal ring (12) (FIG. 4) is composed of a plurality of overlapping segments (16) which co-operate to define a sealing face (15). The segments are located in a housing (14) preferably on the static component with the sealing face (15) confronting a sealing face (10) on the rotating component the arrangement being such that in operation the segments lift away from the rotating component to ride on a gas film leaving a very small sealing clearance therebetween.A secondary seal must be formed between the seal ring and the housing to avoid leakage around the seal ring and this is achieved by a narrow sealing land (23) on the low pressure side-face of each segment being urged into contact with a side-face (22) of the housing by the higher pressure fluid on the opposite side-faces of the segments.

Abstract: Gas turbine engine powerplant has an engine 10 including a fuel pump 14 driven by the engine to supply fuel to the combustor 12 thereof. The pump flow rate varies in accordance with the requirements of the engine as determined by an electric control system 17. Power supply for the control system is derived from an alternator 29 driven by a hydraulic motor 28 fed by pump delivery. A constant flow device 22 arranged between the pump and the motor ensures constant speed for the alternator and thus a constant voltage for the control system.

Abstract: A group of nozzles are submerged in a tank of liquid to produce convergent-divergent vortices and cavitation in a liquid which in turn produce acoustic vibrations which assist in cleaning articles placed in the liquid, or in emulsifying a mixture of liquids. Each such nozzle comprises a body, with a central axis, an inlet at one end for supply of liquid under pressure thereto, and a plurality of discrete outlet ports at the other end transversely spaced from the central axis, the axes of the ports converging externally of the body towards the central axis whereby liquid supplied to the inlet under pressure emerges from the outlets in discrete jets directed to pass close to but not to intersect the central axis of the body.

Abstract: An oil pressure monitoring system for a gas turbine engine having a compressor and a bearing chamber adapted to be supplied with pressurized oil and having means for the drainage of oil therefrom and which is sealed against oil leakage therefrom by pressurized air derived from the compressor. The system comprises first and second switches which are adapted to be actuated by pressure differential, each at different pressure differential values and which are responsive to both the delivery pressure of oil supplied to the bearing chamber and to the pressure of sealing air derived from the engine compressor. A resistance network and a ratiometer are associated with the switches. The arrangement is such that the ratiometer indicates whether the switches have been actuated.

Abstract: A probe for use in measuring apparatus has a base member including a two-dimensional seat for an intermediate member which, in turn, includes a two-dimensional seat for a stylus holder. The two seats face in opposite directions so that the stylus holder can be displaced from the seated position in either of two opposite directions.

Abstract: A coupling between a hub (10) and a shaft (11) has first and second splines (512,513; 530,531) connecting the hub to the shaft. The first splines extend axially and are straight while the second splines are helical. A nut (521) on the shaft urges the hub axially toward a shoulder (527) on the shaft. The first and second splines, being of different helix angles, co-operate to urge the spline faces circumferentially into engagement to take up any clearance therebetween. The different helix angles also have the effect of limiting axial movement of the hub under the nut load. On application of the nut at an initial moderate torque the hub takes up an initial axial position. On further, more powerful, application of the nut, the hub is urged axially against the shoulder (527) which provides a final limit to movement of the hub thereby to avoid undue circumferential stress in the splines.

Abstract: A gas turbine propulsion engine for aircraft of the type in which thrust is provided only from flow of exhaust gases or a combination of flow of exhaust gases and by-pass air, the engine having a cone-shaped spinner with a solid pointed tip portion and a main body portion. The tip portion has at least a surface made of a different material from the substantially rigid material of the main body portion, the at least surface of the tip portion being flexible relative to the body portion at operational rotations of the spinner whereby ice is automatically shed from the spinner due to cracks being developed at the bond between the tip portion and the main body portion. The cracks in the ice developed at the bond are propagated by the surface deflection of the remainder of the tip portion causing any accretion of ice thereon to shed from the remainder of the spinner.

Abstract: A method of manufacture of hollow turbine blades for gas turbine engines comprises forming them in two parts and brazing the parts together. This requires very accurate machining of the two faces of the parts which are to be joined prior to the brazing process. The invention provides a method of machining two confronting faces of parts of an article which are to be joined together. The method includes the step of passing an electrolyte linishing belt (2) FIG. 4 between the confronting surfaces of the two parts (10,11) and in contact with both faces simultaneously while passing an electric current between the parts. Thus one or both faces of the parts are machined using one as the former for the other.

Abstract: A nozzle guide vane assembly for a turbomachine comprises a plurality of segments mounted in an outer casing by means of pins which locate in slots. The slots are angled relative to radial planes so that the reaction force exerted by the pin normal to the length of the slot produces a tangential and radial force. The radial force opposes the couples produced on each segment by gas loads and the tangential reaction force.

Abstract: An air intake structure for a gas turbine engine comprising a duct having an air inlet at its upstream end for the engine and a generally mushroom-shaped center body. The duct and the center body have circular cross-sections throughout their lengths and are coaxial. The center body has a first stem portion extending into the duct and a second mushroom-shaped portion upstream of the air inlet of the duct, the mushroom-shaped portion having a maximum diameter greater than the diameter of the air inlet. An apertured wall circumferentially extends around the maximum diameter of the second portion of the center body, the apertures of the wall being so dimensioned as to cause any small liquid droplets flowing over the upstream face thereof to coalesce into larger liquid droplets. A step immediately downstream of the apertured wall causes the formed larger droplets to be launched from the center body in a trajectory which avoids the air inlet of the duct.

Abstract: A data processing system comprising first and second computers (101;201) and respectively associated first and second transducers (103A; 203A) connected via respective first and second data highways (102;202) to their associated computers, the transducers being enabled upon receipt of associated predetermined address codes output by the computers on respective first and second address highways (110;210), the address highways being linked (310), the data highways being linked (302) and the computers and transducers being arranged so that each computer addresses its associated transducer with the same first address code. In order to obviate the need for complicated switching the address link comprises a converter (314,315) for converting an address code on either address highway into a different, related address code on the other address highway, and each computer is arranged to address its non-associated transducer with the same second address code convertible into the first address code by the converter.

Abstract: A seal for use in rotating machinery such as a gas turbine engine comprises two pole pieces attached to the engine casing and defining a gap in which a magnetic powder is held by a magnetic field generated by a permanent magnet, electro-magnet or a combination of the two. The non-magnetic fins of the adjacent rotor (e.g. turbine blades), extend into the gap and distort the magnetic field so that while there is a small clearance between the fin and the powder, this small clearance can be maintained approximately the same whatever the position of the fin in the gap. A seeding tube allows magnetic powder to be supplied to the gap to make good any loss of powder.

Abstract: Multiple hole drilling by the electro-chemical process, in which individual jets of electrolyte impinge upon a workpiece, presents problems in assessment of hole depth reached and/or of jet deflection through jet orifice blockage. The invention provides a device which looks for the corona at the head of each jet. If the corona is present, the device generates and electrical signal which inhibits the actuation of a further device the function of which is to remove the jet, the corona of which has extinguished. Device also senses the displacement of the corona from a datum and in response, initiates switch off the machine tool.

Abstract: The process involves the steps of:spraying droplets of an aqueous alcohol input solution through spray-bars into a heat transfer fluid contained within a refrigerated process vessel and allowing the droplets to fall through the heat transfer fluid so that some of the water separates out as ice in the droplets;collecting the droplets as a slurry of ice and concentrated solution at the bottom of the process vessel andsubsequently removing the ice to produce a concentrated output solution from the process.The process can be repeated in subsequent process stages up to a limiting concentration of 92% by weight of alcohol in the case of ethanol. The invention includes apparatus in which the process can be performed. Means by which the efficiency of the process may be optimized are also included.

Abstract: A method of casting a blade or vane for a gas turbine engine which enables the production of more complex internal shapes than those which may be made by prior art methods. The method of the invention includes the steps of:making a temporary filler piece from a disposable material,holding the filler piece in place in a die,injecting the core material into the die and causing it to solidify round the filler piece,removing the core from the die,causing the filler to be removed from the core to leave within the core a cavity having the shape of the filler, andusing the core thus produced in an investment casting process to form the blade or vane shape.

Abstract: A gas turbine engine pod installation comprises a core engine with a stiff carcase from which the engine is supported from a pylon. The core engine drives a fan which operates within a fan casing extending to downstream of the core engine nozzle so that the core and fan flows are mixed to provide propulsive thrust when they exit from the fan duct nozzle. The fan casing is supported from the core engine carcase by forward and rearward supports so that these supports, the fan casing and the carcase form a stiff loop of structure which supports and stiffens the carcase.

Abstract: This invention relates to a method of manufacturing laminated material. Particularly to laminated materials for use in the construction of flame tubes of gas turbine engines.The laminated material is manufactured from three sheets, a central sheet, a first sheet, and a second sheet. The central sheet is perforated with an arrangement of equi-spaced apertures. The central sheet with apertures is then secured to the first sheet. A number of channels are machined through the central sheet to leave the first sheet and an arrangement of equi-spaced lands secured thereto. The first sheet is perforated with an arrangement of equi-spaced apertures to form air entry holes. The second sheet is then secured to the assembly to form a laminated material comprising a first sheet with apertures and second sheet separated by an arrangement of equi-spaced lands machined from central sheet.

Abstract: A combustion chamber of a gas turbine engine has an upstream variable rate diffuser for controlling the airflow into first and second annular ducts which partially surround the combustion chamber, primary and dilution air flowing into the combustion chamber from the first annular duct and bypass air flowing into the combustion chamber from the second annular duct. The variable rate diffuser comprises a primary duct and downstream fence located in a secondary duct which has a bleed duct with a variable bleed rate, the outlet of the primary duct being smaller in diameter than the inlet to the first annular duct.