Abstract: The outermost gutter of a reheat system has an extended outer wall to two or three times the length of the inner wall of the outermost gutter. This causes a single vortex to develop instead of the usual two vortices giving an increased basic burning stability.The outer wall also protects the jet pipe from excess heat.

Abstract: A gas turbine engine fuel system of the type using the rotational speed of the high pressure spool as the main control parameter has a trimmer device which reduces the effect of variation of engine geometry in cold starts etc. The trimmer uses the throttle lever angle and engine inlet pressure to compute the desired value of a thrust-related parameter such as weighted mean exhaust pressure, this desired value being compared with the actual value to produce a trim input to the main fuel control unit.

Abstract: In order to cool the annular upstream wall of a gas turbine engine combustion chamber and thereby to prevent the deposition of carbon particles, the wall is formed of upstream and downstream portions which between them define a chamber arranged to receive a flow of cooling air. The downstream portion has a central opening for an airspray fuel burner and on each side of the opening the downstream portion has a pair of facets each facet having apertures for the throughflow of cooling air over the face of the downstream portion.

Abstract: A method of manufacturing a composite material which comprises filaments enclosed in a matrix of a high temperature resistant thermoplastic polymer. The method entails impregnating the filament with a first high temperature resistant thermoplastic polymer in an amount sufficient only to lightly bind the fibres together. The bound fibres are then interposed between sheets of a second thermoplastic polymer and the whole structure subjected to heat and pressure for a time sufficient to ensure impregnation of said second thermoplastic polymer into said filaments and diffusion of the first thermoplastic polymer into the second thermoplastic polymer.

Abstract: A seal for use between the turbine rotor of a gas turbine engine and associated static structure comprises a ring of low-friction material which cooperates with the surface of the rotor to form an air bearing. The ring carries a sealing member which cooperates with a surface of the rotor to form a seal. The air bearing ensures that the sealing member is maintained at a constant spacing from the rotor, and this spacing may thus be maintained at a low value.

Abstract: The fan rotor (10) of a gas turbine engine is driven by a shaft (16) having a first part (16A) supported in a first radial bearing (17) for rotation about an axis (16C). The shaft (16) further has a second part (16B) secured to the rotor for transmitting torque thereto. The second part (16B) is flexible in bending to allow radial displacement of the rotor (10) relative to the bearing (17). Normally, the rotor (10) is supported against said displacement by a second radial bearing (23). If, due to damage, a given dynamic imbalance on the rotor (10) is exceeded, the resulting unbalanced force (F) transversely to the axis (16C) shears the pins (21C) of a coupling (21) provided between the rotor and the second bearing (23). This then permits the rotor (10) to move eccentrically with respect to the axis (16C) by virtue of the resilience of the shaft portion (16B) thereby cushioning the bearing (17) against the force (F).

Abstract: A contact-sensing probe has a movable member including a stylus and is supported on a fixed member at two spaced-apart locations. At each location a spherical element on the one member is situated between convergent surfaces of the other member. A spring urges the movable member into engagement with the fixed member so that at each location the element slides on the convergent surfaces and by virtue of the convergence thereof attains a positive rest position therebetween. The movable member is displaceable from the rest position against the force of the spring when a force is applied to the stylus and is returnable into the rest position by the spring. The elements and surfaces may be electrical contacts, displacement of the stylus being sensed by any one of the contacts being broken. Alternatively displacement is sensed by a proximity sensor.

Abstract: A gas turbine engine comprises an annular combustion chamber (13) intended for low nitrogen oxide emission. The chamber has a pre-mixing section (20) in which an air-fuel mixture is brought to a significant degree of vaporization before issuing through a grill (22) at the end of the pre-mixing section into a main section (21) of the chamber. Pilot sections (18,19) at opposite sides of the pre-mixing section have outlets (28,29) through which burning mixture from the pilot sections is discharged into main section (21). The grill (22) defines openings (35) through which the fresh mixture from the pre-mixing section (20) is discharged across the outlets (28,29) of the pilot sections (18,19) to mix with and become ignited by the burning mixture.The pre-mixing section (20) is an annular duct (33) having walls (15,16) which extend in the direction of the axis of the chamber and are straight in that direction though slightly convergent. The arrangement favors vaporization in the duct without auto-ignition.

Abstract: An alloy is described which is suitable for the manufacture of castings which operate under high temperature conditions (such as nozzle guide vanes for gas turbine engines) but which can also be welded satisfactorily. The alloy comprises______________________________________ Chromium 14.5-16.5% Cobalt 9-11% Molybdenum 5.5-8% Aluminium 1.5-3% Titanium 1.5-3% Tantalum 0-1% Niobium 0-1% Boron 0.004-0.008% Iron 0-0.5% Manganese 0-0.4% Silicon 0-0.2% Nitrogen 0-0.5% Carbon 0.11-0.18% ______________________________________The balance being Nickel apart from incidental impurities.

Abstract: In a gas turbine engine having a can annular combustion system, the diffusion passage between the outlet annulus of the engine compressor and the inlets to the individual combustion chambers located in an annular casing, is partially defined diffusion control housings, one of each of which is located adjacent the upstream end of the respective combustion chamber. Each control housing is wedge-like in planform and has a downstream recess to accommodate the dome-shaped head of the combustion chamber. The control housing increases in circumferential width and radial height in the downstream direction to reduce the diffuser area ratio. Scoops can be provided to guide primary and dilution air into each combustion chamber.

Abstract: A gas turbine engine combustion chamber includes an inlet through which primary air can flow and which is capable of receiving a fuel injector. A cylindrical collar extends from this inlet into the interior of the combustion chamber and the collar may be parallel walled or slightly divergent and one or more rows of equi-spaced apertures can be provided in the collar wall. The presence of the collar has the effect of reducing the rate of carbon deposition on the combustion chamber head and of reducing the levels of emitted smoke.

Abstract: Ducted fan propulsion unit for aircraft has a main duct 3 containing a reversible pitch fan 1 rearward of which is provided a flow splitter 13 dividing the main duct into radially outer and inner branch ducts 3A, 3B. A radial passage 15 in the splitter connects the branch ducts and divides the splitter into front and rear parts 13A, 13B. The part of the inner branch duct forward of the radial passage contains an array of stator vanes 12B and has outer and inner wall surfaces 3B1,3B2 both of progressively reducing diameter to urge the flow through that branch duct toward the inlet of a compressor 8 of yet smaller diameter. Stator vanes 12A in the outer branch duct are arranged forward of the radial passage. The arrangement favors a relatively low axial length of the powerplant.

Abstract: Combustion apparatus for gas turbine engines has a combustion chamber (4,5) provided with fuel/air mixture injection devices (11) in an upstream end wall (9,10) of the chamber. Each device has a passage (17) having inlets (12,15) for air and fuel which mix in the passage and discharge through an outlet (19) initially in a direction along the adjacent surface of said chamber end wall (9,10). The latter wall has a secondary inlet (20) admitting a stream of air transversely to the flow from the passage outlet (19) thereby to generate an oblique flow (19A) having a component movement (Y) away from the combustion chamber wall. This directs inflammable mixture away from the latter wall and simultaneously assists mixing of air and fuel. A cooling film (24,24A) passing along the chamber wall passes over the passage wall (16) and, in certain examples, between the oblique flow and the chamber wall.

Abstract: A gaseous fuel injector for a gas turbine engine, designed to burn gaseous fuels having a wide range of calorific values, includes a fuel nozzle attached to the engine casing and downstream fuel and air inlet means separate from the nozzle, attached to the head of the flame tube. The fuel and air inlet means comprise an outer annular passage containing a row of swirl vanes, through which compressed air from the engine compressor is arranged to flow, and an inner annular passage through which gaseous fuel and compressed air are arranged to flow, the inner annular passage decreasing in cross-sectional area in the direction of flow to prevent the flow of combustion products back into the injector. The nozzle and fuel and air inlet means, which is relatively large, are separate from each other so that the fuel nozzle can be removed and replaced through a relatively small opening in the engine casing.

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 microwave interferometer comprising a source of microwave energy the output of which is equally divided between an antenna and a short circuit. The antenna is adapted for the transmission of microwave energy to and the subsequent reception of reflected microwave energy from an object in close proximity to the antenna. The phase difference between the microwave radiation reflected from the short circuit and the object is directly proportional to the distance between the antenna and the object.

Abstract: Some turbine blades are produced by casting, using the lost wax process. The blades may include cooling air passages and the wall thickness of these is tested ultrasonically i.e. by transmitting and receiving acoustic pulses from and to, a common transducer.Lately the blades, having been cast, are directionally solidified. This process changes the grain structure such that during inspection, pulses received by the blade, have been dissipated. The invention provides ultrasonic testing ability by using a unidirectional pulse transmission system, resulting in pulses which, having passed outwards through the passage wall, still have sufficient energy to effect an indication of wall thickness.

Abstract: The invention relates to piston ring seals. In such seals, manufacturing tolerances, distortions, or wear of the ring itself, or of the sealing surface which it contacts can cause out-of-roundness which produces areas of non-contact between the two components of the seal allowing leakage. The present invention overcomes this problem by providing the piston ring (12) FIG. 3, with a plurality of resilient, tightly packed bristles (18) which are contained within the circumference of the ring where the ring circumference contacts the corresponding sealing surface (5) but which can spring out into contact with the sealing surface over areas where the ring loses contact with it. In the example shown, the bristles project both from the radially inner and outer circumferences and are angled in opposite directions to enable the seal to be rotated into position.

Abstract: In order to facilitate the accurate calibration of a strain gauge amplifier, an electrical circuit is provided, the output of which simulates the output of a strain gauge. A given polarizing current which is the same as that normally applied to the strain gauge is applied to the electrical circuit. Additional, circuitry is provided for producing a single electrical output equivalent to that of the strain gauge.

Abstract: A wax pattern and runner assembly includes resilient means whereby upon expansion of the wax upon removal from a ceramic mould the resilient means are compressed.