Abstract: A low drag surface comprises at its upstream edge, an intermittent linear vortex producing means which extends transverse to the flow over the surface and produces a succession of rolling vortices extending transverse to said flow. The vortices move across the surface and reduce drag in the manner of roller bearings. In preferred embodiments the vortex producing means is mechanical, in the form of an oscillating part or fluid dynamic, in the form of a nozzle arrangement.

Abstract: A gas turbine engine fuel injector comprises a main center body portion at the upstream end of which is located a steam injector. The steam injector is adapted to optionally direct steam into the air inlet of the main body portion so as to reduce the production of the oxides of nitrogen, and optionally increase engine power output.

Abstract: A turbine aerofoil blade is provided with a shroud member at its radially outer extent for engagement with the corresponding shroud members of adjacent aerofoil blades. A cooling air duct within the shroud member directs cooling air to the abutment region of the shroud member so as to provide impingement cooling thereof. Ports provided in the cooling air duct direct a flow of cooling air from the duct over the outer surface of the abutment region so as to provide additional cooling thereof.

Abstract: A flow inducing means 110 for use in an anti-icing system for a nose bullet 10 of a gas turbine engine of the type in which hot gas is caused to flow along the center of a rotating tube 7,62 towards the nose bullet 10 to heat it, and cooled air is centrifuged to the surface of the bore of the tube 7,62 and is displaced rearwardly along the tube. The tube 7,62 is open at its rear end, and the flow inducing means 110 is positioned adjacent the open end. The flow inducing means 110 comprises a plurality of radial vanes 111 which enters in a radially inwards direction and the vanes 111 are shaped and positioned to redirect the gas axially along the center of the tube 7. The flow inducer 110 may include a shroud 115 which has a circumferential inlet opening and an axial facing outlet 116. The shroud may serve as a flow separator which separates the incoming hot gas from the cooled gas exiting the tube.

Abstract: In order to facilitate efficient use of high pressure cooling air in a turbine rotor blade its aerofoil has a triple-pass convoluted cooling air duct in its leading edge region, and a triple-pass convoluted cooling air duct in its mid-chord region, both of them being fed from a common high pressure inlet in the root of the blade. The trailing edge region has a single-pass duct fed by low pressure cooling air from an inlet located just under the blade platform. The shroud of the blade also has cooling air passages and these are fed from the ends of respective ones of the ducts. Air from the ducts also exits through rows of film cooling holes to film cool the concave flank of the aerofoil and through a row of holes in its trailing edge to remove heat from the thinner metal section in that area.

Abstract: A nickel based alloy is devised, for the purpose of using it as a brazing foil to join parts of a nickel based superalloy component together to make a whole, or for using it as a powder bound by an acrylic or water based binder, to build up damaged surfaces of a nickel based superalloy. In each case, the finished product has the mechanical strength characteristics of the base metal.

Abstract: The present invention relates to turbofan gas turbine engines. In conventional high bypass ratio turbofans the large variations in the free air stream flowing into the fan duct inlet is accommodated by a thick lip and a long, thick fan casing to prevent air flow separation from the outer surface of the fan casing, but produces a heavy fan casing and large drag values. In the invention a turbofan comprises a core engine which has a core casing, and a fan assembly positioned downstream of the core engine. The fans operate in a fan duct defined by the fan casing. The core casing has an external form upstream of the fan duct inlet which affects the airflow streamlines flowing into the fan duct inlet to cause it to adopt a flow path which is near alignment with the length of the fan casing to reduce fan casing weight, length and drag.

Abstract: This invention provides an apparatus for and method of manufacturing a brush seal. The apparatus comprises an annular former 22 having a radially outer 24 and a radially inner 30 portion radially separated from each other by an amount G and held relative to each other by locating means 32, and further includes a travelling wire electro discharge machining device and a guide tube. A brush seal 10 is wound onto the former in the usual manner and the filament material 38 cut in the region of the gap G by the travelling wire 44. The wire is inserted between the filaments by first inserting a tube 52 therebetween and passing the wire 44 therethrough. Machining of the filament material is achieved by traversing the wire around the gap G.

Abstract: The temperature of an object (10) is measured by monitoring the thermal Doppler broadening of resonances in its neutron transmission characteristics, as neutrons (11) pass through it from a source (12) to a detector (14). Various surfaces (18, 20, 24) of the object are each plated with a different element, such as platinum, iridium and rhenium respectively. By monitoring the Doppler broadening of resonances due to platinum, the temperature of the platinum surface (18) can be determined; and the temperatures of the iridium surface (20) and the rhenium surface (24) are determined likewise.

Abstract: To modify a turbulent boundary layer flow over a surface to reduce its drag, a series of streamwise riblet projections is provided on the surface arranged in a pattern consisting of spaced large height projections between which are a plurality of smaller height projections. The latter inhibit turbulent eddy motions from penetrating deep into the grooves between them and so displace the turbulent motion away from the wall. The larger projections control the longitudinal vortices or streaks that are characteristic of turbulent boundary layer flow and promote energy transfer to the smaller scale secondary vortices associated with the smaller projections.

Abstract: A ducted fan gas turbine engine includes for surge control capability in the form of a downstream fan cowl portion which can be moved to open a gap of variable magnitude. Fixed cowl portion has a resilient downstream edge which effects a good seal against blocker flaps when not in use. The blocker flaps are moved across the fan duct on the cowl portion moving a sufficient distance in a downstream direction.

Abstract: A method of non-invasively measuring strain and temperature of an object, substantially simultaneously, using neutrons of selected energy levels is described. A pulsed neutron source is made to emit thermal and epithermal neutrons in a collimated beam directed at a target object. Temperature is monitored by observing the thermal Doppler broadening of resonances in the neutron transmission characteristic for the epithermal neutrons and strain is measured from observations made of changes to the thermal neutron diffraction pattern.

Abstract: The present invention relates to air bleed arrangements on a compressor of a gas turbine engine. A rotor of the compressor has a plurality of stages of rotor blades, and the rotor is formed from a plurality of axially adjacent rotor discs. Two axially adjacent rotor discs define a chamber therebetween for a radially inward flow of bleed air. The rotor is provided with a plurality of apertures in rotor disc which bleed air from the compressor and supply the bleed air to the chamber. The adjacent rotor discs have opposing radially extending surfaces, and one of the opposing surfaces has a plurality of circumferentially spaced radially extending vanes and radially extending grooves which direct the bleed air radially inwardly to minimize pressure losses in the bleed air flowing through the chamber. This arrangement is not complex, is relatively easy and inexpensive to manufacture, has reduced weight and allows compressor to be manufactured by welding the rotor discs together.

Abstract: The head assembly of a combustion chamber, within which burning of mixed fuel and air takes place, is fixed to surrounding structure in a manner which enables differential expansions of the parts of which the assembly is comprised, without generating stresses through reaction of one part upon another.

Abstract: An aerofoil balde rotor assembly in which a plurality of aerofoil blades having circumferentially extending platforms are located on the periphery of a rotatable disc. Each of the platforms is provided with tracks on its radially inner surface. The tracks of adjacent platforms define a convergent seating for a ceramic spherical damping member. Each spherical damping member frictionally engages the tracks of adjacent platforms simultaneously upon rotation of the assembly so as to provide aerofoil damping.

Abstract: A method of identifying a workpiece in the course of its manufacture, in which the workpiece carrying an existing identification marking is supplied to an apparatus in which it is to be subject to a process that removes or obscures the marking, the marking is machine-read after the workpiece has been placed in the apparatus but before the process begins, data from the reading is put in store, and at the end of the process the identification is re-marked on the workpiece in accordance with the stored data while the workpiece is retained in a predetermined position in the apparatus.

Abstract: A method of flow visualization comprises the steps of coating the surface of a component in a pigmented oil-based paint of non-gelling characteristics, applying dry dye particles, which are soluble in the oil based paint to the surface of the coating and passing a fluid flow over the component.The fluid flow causes the dye particles to translate across the coating so that regions of the particles that are in contact with the coating dissolve to leave trails on the surface of the coating which are indicative of the relative strengths of the fluid flows acting on the surfaces of the component.

Abstract: An electromagnetic gun comprises a barrel for containing and directing an electrically conductive projectile and a plurality of inductors which are arranged in series relationship along the barrel so as to create magnetic fields which accelerate the projectile along the barrel. Each inductor is associated with a pair of rail electrodes within the barrel bore which, when bridged by the projectile, short circuit their associated inductor to provide additional acceleration of the projectile.

Abstract: A jet pipe for jet propulsion in aircraft has in flow-series a first or fixed duct 13, a second duct 14 and a third duct 15. The second duct 14 is supported on the first duct 13 for rotation about a common axis 13A, 14A of these two ducts. The third duct 15 is supported on the second duct 14 for rotation about an axis 19A having an angle oblique the axis 14A of the second duct. A ring 30 is supported on the second duct 14 for rotation about the axis 14A thereof. A bracket 31 mounted on the ring 30 has a guide and slide connection 32,33 with the third duct 15. A single drive shaft 24, mounted on the fixed duct 13, is connected to rotate the second duct 14 and the ring 30 in opposite directions. The guide and slide connection effects a corresponding rotation of the duct 15 about the axis 19A. The resulting relative rotation of the ducts 14,15 results in the duct 15 moving so that the axis 15A thereof moves through an angle .beta. while remaining in a given plane 11A, 11B.

Abstract: A patient restraining device suitable for use in physiotherapy comprises a framework which in use is located at the foot of a bed. A roller is rotatably mounted on the framework, and a belt is secured to and wound around the roller. A harness is secured to the free end of the belt, and the harness is provided with cushioned straps. A length of belt is unwound from the roller to suit the particular patient, and the roller is locked in this position by a ratchet wheel and pawl spindle. The patient lies on the bed over the harness and belt so that the patients feet are adjacent the framework and the cushioned straps are wrapped around the patients legs to hold the patient. The patient restraining device allows a single physiotherapist to perform physiotherapy while the patient is prevented from moving away from the framework.