Showing papers by "Rolls-Royce Limited published in 1979"

Multi-layer acoustic linings

Abstract: A multi-layer acoustic lining, e.g. for a flow duct in a gas turbine aeroengine, includes Helmholtz-type and tube-type resonators sandwiched between backing and facing sheets. In the invention, the ends of the tube-type resonators abut the Helmholtz resonators but are acoustically divided from them by partition means in such a way that the tube-type resonators differ from each other in resonant frequency. Variation of resonant frequency in the tube-type resonators is achieved by variation of their lengths according to which portion of the partition means acoustically divides them from the Helmholtz-type resonators, the partition means being arranged either step-wise or inclinedly between the backing and facing sheets.

Lubricant supply device

Abstract: A lubricant supply device adapted to direct lubricant from a source of pressurized lubricant to apparatus to be lubricated. The device is provided with a rotatable chamber containing a limited quantity of lubricant so that in the event of a failure in the supply of lubricant to the device, lubricant contained within the chamber is centrifugally pumped to the apparatus to be lubricated in order to maintain a limited continuity of lubricant supply.

Guide vanes for gas turbine engines

Abstract: A vane for a gas turbine engine comprising a hollow body externally of aerofoil form. The inner surface of the body is provided with confronting grooves, extending in a direction along the length of the aerofoil form, at a location intermediate the leading and trailing edges of the aerofoil form for receiving two inserts. The first insert comprises two perforated panels situated inside a trailing region of the aerofoil form and defining therewith one or more air passages between the insert and the wall of the body. The first insert has portions which engage in the grooves in the wall of the body, and is provided with confronting grooves extending in a direction along the length of the aerofoil form at a location intermediate the leading and trailing edges of the aerofoil form. The second insert comprises a first panel extending across the void in the body, and has edges which engage in the confronting grooves in the first insert. The second insert has a second panel closing at least part of an end of the void in the body.

Combined pilot and main burner

Abstract: The invention relates to a fuel system for a gas turbine engine wherein an annular combustion chamber 10 has an annular series of pairs of first and second nozzles 15,16. In one mode of operation fuel is supplied only to the first nozzles 15. In another mode, fuel is supplied also to the second nozzles. The change has to be made during operation of the engine. If the first and second nozzles had separate supply manifolds, the manifold pertaining to the second nozzles would have to be primed and purged respectively when initiating and terminating the use of the second nozzles. To avoid this difficulty the first and second nozzles are supplied by a single manifold 12 and the second nozzles are controlled by individual valves 21 situated close to the latter nozzles and operated collectively by a fluid pressure supply 26,27.

Air cooled turbine for a gas turbine engine

Abstract: An air cooled turbine which has cooling air provided through pre-swirl nozzles into an annulus formed between radially inner and outer seals and then into cooling air inlets to the turbine blading, has leakage air deflector means to prevent the leakage flow from the inner to outer seal interfering with the cooling air flow. The deflector means may comprise leakage flow inlets adjacent the inner seal, channels extending radially and cooperating with the turbine rotor to provide passages for the leakage flow to a location radially outboard of the cooling air inlets to the turbine blading, and open portions through which the cooling air can flow to the cooling air inlets. The channel outlets of the deflector may be arranged so that some of the leakage flow can be directed to cool a less critical part of the turbine blading the remaining leakage flow being directed radially outboard of the cooling air inlets to a more critical part of the turbine blading which are arranged to receive the normal cooling air flow.

Root attachment for a gas turbine engine blade

Abstract: A root attachment of the firtree type for a blade of a gas turbine engine. The shape of the root falls within certain closely defined parameters which have been found to give optimum properties to the root. Thus the arrays of teeth forming the root diverge at 35°±1°, the pair of angled faces making up each tooth are at an angle of 60°±1° to each other, and each outer tooth face is at 45°±2° to a normal to the central plane of the root. Also the ratio of the tooth height to the radius of the radiused portions lies in the range 1.5:1 to 2:1.

Electro-chemical-machining of aerofoil blades

Abstract: An electrode assembly for electro-chemically machining an article, such as an aerofoil shaped blade for a turbo machine. The assembly comprises a plurality of electrodes 2,3 for location adjacent a workpiece 7. Each electrode 2,3 is constrained to move in a first direction towards each other and towards the workpiece 7 and has two side members 22,23 carried by a main body 21. The side members 22,23 are constrained to move with the main body 21 and also relative to the main body in directions parallel to the first direction. The side members 22,23 advance ahead of the main body 21 and when they abut the side members 22,23 of the other electrodes 2,3 their advancement is stopped while the main bodies 21 of the electrodes 2,3, continue to approach each other for a predetermined distance. In this way edge effects during machining are eliminated enabling an accurate shape of article to be produced.

Probe having passive means transmitting an output signal by reactive coupling

Abstract: Apparatus for monitoring the state of a first circuit (19) by means of a second circuit (29) has an inductive coupling (23) linking the circuits across a gap (32). The second circuit embodies an oscillator (27) producing primary oscillations in that circuit and, through the coupling, secondary oscillations in the first circuit (19). If the state of the first circuit (19) is changed as by opening or closing of contacts (17,18), the resulting change in the impedance of the first circuit results in a change in the frequency of the primary and secondary oscillations. The second circuit (29) is connected to a detector (35) producing a signal (37AI) when the frequency changes. Instead of an inductive coupling, a capacitative coupling may be used. The apparatus is described as applied to a machine for measuring length. The first circuit (19) is embodied in a probe (12) whereby the machine contacts a workpiece to be measured. The first circuit is opened by such contact. The second circuit (29) is embodied in a head on which the probe is releasably mounted. Since the first circuit (19) is a passive one, the probe does not need an independent power supply, and a power supply in the head serves any one such probe that may be mounted on the head.

Products made by powder metallurgy and a method therefore

Abstract: An article such as a gas turbine rotor blade or bladed rotor is made by consolidation of metal powders contained in a mould using the technique of hot isostatic pressing. Different properties are produced in different portions of the mould corresponding to those parts with either metal powders of different alloys or with metal powders made from one alloy but differently pretreated, e.g. by rolling, to impart mechanical strain into the powders.

Shock Boundary Layer Interaction on High Turning Transonic Turbine Cascades

Abstract: In recent years, the increase in turbine entry temperature, coupled with the capability of higher blade speeds, has led to greater interest in the high work capacity single-stage transonic high pressure turbine. However, the transonic turbine has a performance penalty compared with an equivalent subsonic unit due mainly to shock induced losses. A cascade investigation into the influence of supersonic shocks on turbine blade performance is reported. Two different rotor profiles designed for the same duty were tested in the rectilinear cascade wind tunnel at DFVLR-AVA Goettingen. The results indicate the sensitivity of the cascade performance to shock boundary layer interaction. The importance of Schlieren optics flow visualization (including high-speed film to show the unsteady behavior of the flow) in evaluating the results is discussed.Copyright © 1979 by ASME

Control systems for multi-stage axial flow compressors

Abstract: A control system is provided for the multi-stage axial flow compressor of a gas turbine engine. The control system embraces a stage of variable angle guide vanes, a first detector adapted to detect a first pressure in the compressor which is influenced by the vane angular setting, and a second detector adapted to detect a second pressure independent of the vane setting but bearing a functional relationship to the rotational speed of a compressor of the engine. A control unit is adapted to use the pressures detected by the detectors to cause an actuation mechanism to adjust the angular setting of the guide vanes in a predetermined manner dependent upon the ratio of the second pressure to the first pressure.

Aerofoil member for a gas turbine engine

Abstract: A blade or vane structure for a gas turbine engine comprises a hollow aerofoil member and a cooling air entry tube within the hollow aerofoil member, the aerofoil member and the tube comprising a unitary cast structure. To make this structure it is proposed that a lost wax casting process should be utilized, with the internal cavities formed using ceramic cores formed with the aid of temporary, disposable pieces which define the space eventually occupied by the tube.

Fluidic control of airflow in combustion chambers

Abstract: The airflow from the compressor of a gas turbine engine into the combustion chamber or chambers principally comprises combustion air which enters the upstream end of the combustion chamber and dilution air which enters the combustion chamber at some point downstream of the combustion chamber inlet, the combustion air being made up of primary and secondary air entering the combustion chamber primary and secondary zones. In order to cope with the control of emissions from the combustion chambers, it is desirable to control the combustion air fuel ratio over the engine operating range by controlling air mass flow to the combustion and dilution zones of the combustion chamber. The invention proposes that this control can be achieved by providing a variable rate diffuser upstream of the primary, secondary and dilution air inlets, the variable rate diffuser comprising vortex generator having an associated variable air bleed. The air bleed functions to control the strength of the generated vortex which in turn controls the rate of diffusion of the air supply to the combustion chamber.

Porous metal sheet laminate

Abstract: A sheet laminate is utilised in the manufacture of a combustion chamber for a gas turbine engine. The laminate has passages therethrough, which connect with ambient atmosphere via holes. The arrangement creates local relatively thick portions or lands which cause stress concentrations along the passages and lines of holes. Therefore pockets are machined in the rear face of each land, so as to reduce the differences in thickness of the laminate and thereby ensure the more even distribution of stresses.

Nozzle guide vane assembly for a gas turbine engine

Abstract: A nozzle guide vane assembly for a gas turbine engine comprises a circumferentially extending array of angularly spaced apart aerofoils each having projections adapted to engage with structure to retain the aerofoil in its longitudinal direction. Inner and outer platform members are separate from the aerofoils and each comprises a thicker support skin and a thinner inner skin. Both skins have aerofoil shaped apertures through which the aerofoils project, the support skin retaining the aerofoil against twisting, circumferential or axial loads and the inner skin serving to define a respective boundary of the gas flow through the assembly. The aerofoil is free to slide through the apertures sufficiently to permit relative expansion in a direction longitudinal of the aerofoil, and sealing means are associated with the inner skins and provide a seal between the skins and the aerofoils.

Combustion equipment for gas turbine engines

Abstract: Combustion equipment designed to reduce smoke levels and the production of nitrogen oxides has a fuel burner mounted in the upstream wall of a combustion chamber, the fuel burner comprising a central duct partially surrounded by an annular duct, each of the ducts having an array of swirl vanes at their upstream ends and fuel inlet apertures downstream of the respective arrays of swirl vanes. The fuel supply to each of the ducts can be controlled to apportion the fuel flow between the two ducts in dependence of an engine parameter, such as speed, so that at low speeds a majority of the fuel is injected into the annular duct while at higher engine speeds, a majority of the fuel is injected into the central duct.

Method for producing a composite structure

Abstract: A method of producing a composite structure consists of winding a resin impregnated filament tow onto a former or formers having surfaces which correspond with a portion of the finished article, removing the fibre sheets from the former or formers, and placing them in a mould which corresponds in shape to that of the complete article, and pressing the fibre within the mould to consolidate the finished article.

Cooling air supply arrangement for a gas turbine engine

Abstract: A cooling air supply arrangement for a gas turbine engine comprises a rotor, a source of cooling air at a high supply pressure, a first passage adapted to transmit a first flow of said cooling air to a first area of the rotor and to reduce its pressure to a first pressure lower than said high supply pressure, and a second passage adapted to transmit a second flow of said cooling air to a second area of the rotor and to reduce its pressure to a second pressure lower than the first pressure. A seal is provided to resist flow of cooling air from said first to said second area, and in order to reduce the leakage through the seal it incorporates part of the second passage including nozzles oriented to direct at least part of said second flow against the leakage flow. In this way the leakage is reduced and simultaneously the pressure of the second flow is reduced.

Method for removing aluminide coatings from nickel or cobalt base alloys

Abstract: A method of removing aluminium containing alloy coatings from nickel or cobalt base alloy substrates in which the coated substrate is immersed in an aqueous mixture of nitric and sulphamic acids until coating dissolution is complete. A solution containing 5 to 30% vol./vol. nitric acid and from 5 to 30% wt./vol. sulphamic acid is preferred.

Method of and apparatus for forging metal

Abstract: A worn titanium blade for a gas turbine engine has metal displaced at its aerofoil tip, so that the aerofoil can be dressed to restore it to length. The titanium is not amenable to cold forging, or to being entirely heated, a forge is therefore provided which has dies which contact only the immediate area containing the metal to be displaced. The dies are heatable so as to heat the said area by conduction and powered so as to apply suitable pressure in a way which brings about isothermal displacement of the titanium.

Method of welding by electron beam

Abstract: A pair of superalloy workpieces are electron beam butt welded and the weld is achieved by pulsing the electron beam and, at the same time, moving it on a circular path. The combined relative traversing of beam and workpieces and circularizing of the beam, causes each pulse of electrons to overlap the metal melted by the previous pulse.

Cambered blade or vane for a gas turbine engine

Abstract: A blade or vane for a gas turbine has a cambered aerofoil made up of a plurality of single crystals of an alloy. Each crystal extends longitudinally of the aerofoil and has a predetermined three-dimensional orientation different from that of the other crystals such that it has an optimum value of a chosen property in directions longitudinal and transverse of the aerofoil.

Fuel control systems for gas turbine engines

Abstract: A fuel control system for a gas turbine engine for an aircraft comprising two modes of operation, a first mode in which the net thrust of the engine increases with an increase in the forward speed of the aircraft and a second mode in which the net thrust of the engine is caused to decrease with an increase in the forward speed of the aircraft, a selectively operable control device such as a valve or a valve with a least wins device being provided for selecting one of the modes of operation at a time.

Variable configuration exhaust discharge opening for a jet propulsion engine

Abstract: A gas turbine jet propulsion engine has a rectangular exhaust gas outlet 14. A pair of U-shaped tracks 21,22 one on each side of the outlet and which extend downstream of it, support rollers carrying the plates 24a etc. of a pair of articulated deflectors 24,26, one above and one below the outlet. The deflectors are translatable along the tracks between the final exhaust discharge opening of the engine. The configurations include a convergent divergent nozzle, a thrust vectoring nozzle and thrust reversing outlets.

Variable area nozzle for a gas turbine engine

Abstract: In a jet pipe and variable area final nozzle assembly, the jet pipe 12 is necked at a region upstream of the final nozzle to reduce the diameter of the remainder of the jet pipe downstream of the neck to a diameter more nearly equal to but not less than the maximum throat area of the nozzle. The nozzle flaps are pivoted to the end of the jet pipe, although they could alternatively be translatable, and have an upstream portion 20 which overlies the jet pipe. An actuating mechanism preferably in the form of a unison ring 30 operated by jacks is mounted around the reduced diameter portion of the jet pipe and operates on the upstream portions of the nozzle flaps via a roller and cam arrangement 26, 24 to vary the area of the nozzle. An outer fairing 14 which now need be of no greater diameter than the maximum diameter of the jet pipe surrounds the jet pipe and the actuating mechanism (see FIG. 1).

Method of brazing with replaced braze powder

Abstract: The invention overcomes the difficulty of applying a layer of material e.g. braze material, to a concave surface, by rotating the workpiece having the concave surface, about the axis of revolution of the concavity and the material is applied thereto in powder form and held by centrifugal force. Before stopping rotation, a liquid binder is applied to the material and allowed to set, so as to make the resulting mixture self supporting.

The Management of Information Flow in a High Technology Development Environment

Abstract: Effective management of a gas turbine development programme under commercial airline pressures demands very careful balancing of two separate cycling commodities.One is experimental engines and component parts or ‘hardware’. The other is data, information and conclusions, hereafter referred to collectively as ‘decisionware’.While techniques for hardware management are well documented, equivalent techniques for planning, monitoring and motivating decisionware activities are less developed. This paper describes experimental methods which have been evolved, and applied to some development activities within the Derby Engine Group of Rolls-Royce Limited. These methods include simulation modelling and performance monitoring of a staff organization and aim to achieve higher combined effectiveness of the two meshing cycles described.The work occupied a period of one man year and has applications in development associated departments outside the original field of study.

Inspection of electrically non-conductive workpieces

Abstract: A method of inspecting wax patterns for use in the lost wax casting process comprises coating the pattern with aluminum by vapor diffusion and subsequently inspecting the coated pattern using inspection apparatus adapted for the non-contacting dimensional inspection of electrically conductive workpieces.

Method of forming a porous sheet

Abstract: Sheet metal plate has grooves formed in a side, by the electro chemical/photo resist method Holes are formed in the same way, in the groove bottoms and pass through the metal thickness In order to ensure that the holes have substantially parallel, dimensionally accurate walls, the sheet thickness to hole diameter ratio, is effectively reduced by first forming the holes to half depth in one side of the sheet, then forming grooves in the same side of the sheet in which the half holes are formed, so as to remove the half holes but leave depressions in the groove bottom at the positions where the half holes had been previously formed, then forming the hole proper for the holes by removing the metal from the opposite side of the sheet