Abstract: A crystal selector pattern for use in forming a mould in an investment casting process, which is formed from a water-soluble organic composition which, in a preferred embodiment, comprises 80% urea.

Abstract: A gas turbine engine casing includes a tip treatment ring 20 which comprises end supports 18 which support tip treatment bars 16. Each tip treatment bar 16 is mounted at its ends within the respective end supports 18 by means of damping elements 22, which isolate the bar 16 from the end supports 18. The elements 22 damp vibrations induced in the tip treatment bars 16 so inhibiting the initiation of high cycle fatigue cracking.

Abstract: A combustor arrangement (8) for a gas turbine engine (3) comprising a combustion chamber, fuel nozzles(52a,52b), and a bled diffuser (7) located upstream of said combustion chamber to, in use, direct an airflow from an upstream compressor (6) into the combustor (8). The fuel nozzles (52a,52b) arranged in use to supply fuel into the combustion chamber where it is mixed and combusted with the airflow from the compressor (6). The bled diffuser (7) adapted to bleed off a portion of said airflow from a main airflow into the combustion chamber. At least one bleed duct (46) is connected to the bled diffuser (7) to return and direct the air bled from the diffuser (7) to a main gas flow through the engine (3) at a location downstream of the fuel supply means (52a,52b). The bled air from the diffuser (7) preferably providing cooling of a part of the gas turbine engine (3), for example part of the turbine (10) or combustor outlet vane (58), downstream of the combustor (8).

Abstract: A combustion chamber assembly (22) comprises a primary, a secondary and a tertiary fuel and air mixing ducts (54,78,98) to supply fuel and air to primary, secondary and tertiary combustion zones (40,42,44). Each of the primary, secondary and tertiary fuel and air mixing ducts (54,78,98) comprises a pair of axial flow swirlers (56,60,80,84,102,104) arranged coaxially to swirl the air in opposite directions and fuel injectors (62, 86,106) to supply fuel coaxially of the respective axial flow swirlers (56,60,80,84,102, 104). Valves (66,90) are provided to control the supply of air to the primary and the secondary fuel and air mixing ducts (54,78) respectively. A duct (122,116) is arranged to supply cooling air and dilution air to the combustion chamber (22). The amount of air supplied to the primary, secondary and tertiary fuel and air mixing ducts (54,78,98) and the duct (122,116) is measured.

Abstract: A gas turbine engine comprises a centrifugal compressor (4), an air diffuser (8), a heat exchanger (10), combustion apparatus (12), and first and second turbines (14,18). The combustion chamber assembly (22) comprises a primary, a secondary and a tertiary fuel and air mixing ducts (54,78,98). The compressor (4), diffuser (8), primary and secondary fuel and air mixing ducts (54,78) and turbines (14,18) all comprise means (6,8,16,20) for varying the mass flow area at their inlets such that in operation the amount of air mass through each component may be independently variable. Under part power conditions the mass flow is reduced and under full power conditions the mass flow is increased thereby maintaining a substantially constant gas cycle throughout the engine.

Abstract: A fuel injector assembly designed to withstand a predetermined impact load resulting from ingestion of a bird or other foreign object into the combustion stage of a gas turbine engine comprises a body member adapted to be mounted adjacent to and to extend into the combustion chamber and an abutment member disposed downstream of the injector assembly in the direction of air flow through the combustion stage, the arrangement being such that the body member moves into contact with the abutment member when subjected to an impact load in excess of the impact load it is designed to withstand.

Abstract: A hollow airfoil (8) has an internal air system in which a cooling gap (44) adjacent the internal surface (52) is formed by a liner insert (14) consisting of a shaped panel (14a). At least some of the cooling air circulating through the gap (44) enters through a screening arrangement, comprising exclusion apertures (50), which removes particulates over a predetermined size (e). The air is fed into a plenum chamber (46) which may be formed by a pressing in the insert panel (14a). There are two exits from the plenum (46): a first is through the screening arrangement to admit filtered air to the wall cooling gap (44), and a second is via apertures (54) in the airfoil wall (18) the sizes (d) of which apertures are large enough to pass the screened particulates into the gas path.

Abstract: A rotary cutting tool formed with at least twenty helical cutting teeth.

Abstract: A component (24) for a gas turbine engine rotor assembly comprises a wall member (26) for at least partially bridging a space between adjacent rotor blades (18) and a root member (42) for insertion into a groove in the rotor disc (18) of the rotor assembly. The root member (42) includes bearing surfaces (46) for bearing against complementary surfaces (48) in the groove on rotation of the disc. The annulus filler (26) comprises a plurality of layers of carbon fiber reinforced plastics material, the layers being oriented substantially perpendicular to the bearing surfaces (46).

Abstract: A brush seal designed for use between regions of high pressure differential and in an environment in which there is disturbed flow has a bristle pack sub-divided into a plurality of bristle pack regions with a leaky diaphragm between each region. The brush seal may comprise an assembly of individual seals with diaphragms between them or a single bristle pack which is sub-divided by at least one internal diaphragm. The diaphragms are preferably compliant and designed to allow a predetermined leakage flow between bristle regions. The leakage flow has several functions: it causes the pressure differential across the whole seal assembly to be more evenly distributed, and by providing an amount of flow in each pack this acts to calm the bristles thus helping to ensure each bristle region effectively contributes to the seal performance.

Abstract: A gas turbine engine core casing comprises axially adjacent portions (20,21) that are flanged to receive bolts (28) that attach the portions (20,21) to each other. One of the casing portions (20) is provided with flange (23) that is of L-shape cross-section to provide local enhancement of the rigidity of the casing portion (20). Such rigidity enhancement provides improved debris containment in the event of the failure of rotor components within the casing.

Abstract: A high rhenium-containing nickel superalloy article (10) has a multilayer coating (12) comprising a barrier coating (14) and an aluminide coating (16). The aluminide coating (16) is a corrosion and oxidation protective coating for the superalloy article (10). The barrier coating (14) comprises an alloy with a similar composition to the high rhenium-containing nickel superalloy article (10) but with less rhenium. The barrier coating (14) minimises diffusion of elements between the aluminide coating (16) and the superalloy article (10) to minimise the formation of topologically close packed phases at the interface between the superalloy article (10) and the multilayer coating (12). The barrier coating (12) preferably has some rhenium to minimise diffusion of rhenium from the superalloy article (10) to the barrier coating (14).

Abstract: Power generation equipment (10) comprises a compressor (11,12) into which finely dispersed water is directed. Air compressed by the compressor (11,12) is directed into combustion equipment (13) where it is mixed with steam and fuel before combustion takes place. The resultant combustion products pass through two turbines (14,15), the second of which (15) is a power turbine. The exhaust efflux from the power turbine (15) is then cooled to such an extent that its pressure falls to below atmospheric pressure. The carbon dioxide is removed from the efflux by means of a sequestration membrane (33) before the pressure of the efflux is raised to above atmospheric pressure by a further compressor (16) driven by the power turbine (15). The equipment (10) is very efficient and produces low levels of pollution.

Abstract: A catalytic combustion chamber is provided with at least two cataleptic combustion zones arranged in flow series, In a first mode of operation fuel is supplied from first fuel injectors, positioned upstream of the first catalytic combustion zone, into the catalytic combustion chamber and is burnt in the first catalytic combustion zone in order to preheat the subsequent catalytic combustion zones. In the second mode of operation the supply of fuel to the first fuel injectors is reduced and fuel is supplied from second fuel injectors positioned between the first catalytic combustion zone and the second catalytic combustion zone into the space between the first catalytic combustion zone and the second catalytic combustion zone. This prevents the first catalytic zone becoming overheated, and reduces the possibility of the second and third catalytic combustion zones becoming overheated and allows the optimum catalyst to be selected for the first catalytic combustion zone.

Abstract: An apparatus for detecting pressure in a hollow fan blade of a turbofan gas turbine engine comprises a magnetostriction transducer arranged in a sub chamber of the fan blade which is interconnected to a main chamber. A magnetic coil is arranged in the fan casing of the turbofan remote from the fan blade, and an alternating current is supplied from a supply to the magnetic coil to produce an alternating magnetic field. The alternating magnetic field causes the magnetostriction transducer to generate vibrations in the fan blade and the magnetostriction transducer. A magnetic search coil detects changes in the magnetic field, which corresponds to the vibrations, and a processor analyses the vibrations to determine if there has been a change in the resonant frequency of the vibrations which is indicative of a change in the pressure in the fan blade. The processor supplies a signal to a display or to an alarm. The change in the pressure is indicative that the fan blade is cracked and needs replacing.

Abstract: An aerofoil blade damper comprising an elongate member which is inserted within a core passage of the blade and extends within the blade with the damper retained therein at one end which is closest to the blade root with the remainder of the damper free to move relative to and within the passage; such movement generating friction which dissipates any vibration. The damper comprises a plate insert including at least two discrete substantially oppositely directed contact regions which are arranged, in use, to frictionally engage the passage. The discrete contact regions may be provided by protrusions in the form of contact pads or arms extending from the plate or be provided by the corrugations of the plate. A contact load on the contact regions is provided by the resilience of the damper, an interference fit of the damper and/or centrifugal loading of the damper and contact regions during operation.

Abstract: An axial flow turbomachine has at least one circumferential row of aerofoil members in which at least one of the two end walls (33) between successive blades (30) is given a non-axisymmetric profile to modify the boundary layer flow at the wall. In one form of the profile, a convex region (33) adjacent each member pressure surface (35) and a complementary concave region (34) adjacent each member suction surface (34) extend over at least a major part of the blade chord lengths to reduce the transverse pressure gradient and thereby reduce vortical energy losses. In another form of the profile, at least one end wall (33) has complementary convex and concave regions (50,51) extending through the zone of the trailing edges of the members (30) on the suction end pressure surface sides (34,35) respectively of each member, thereby to reduce over turning of the flow. Both forms of profiling can be employed in combination.

Abstract: A high pressure fuel system includes tapped high pressure flows (22,24) with restrictors (44,46) to provide low pressure flows with which, via a valve (50) to enable either a low pressure flow to bias a main, high pressure fuel cut off valve (16) to close at a steady given rate, or a high pressure flow across a further valve (30), to close the valve (16) at a faster rate.

Abstract: A method of forming an article comprising in combination the steps of: constructing in a computer (6) memory a first datafile 60) which is a definition of a three dimensional volume model of an article; executing a computer program (42), which reads the first datafile (60) and performs an algorithm which deconstructs the three dimensional volume model to produce a second datafile (62) comprising a string of sequential relative spatial co-ordinates describing a tool path (90,91) through the three dimensional volume model of the article; operating a multi-axis welding robot (2) to position the welding head (16) relative to the worktable (12) such that the relative movement follows the path (90,91) defined by the second datafile (62). The operation of the welding head (16) also being controlled to deposit a weld bead as it follows at least a part of the path to build up a solid representation of the three dimensional volume model of the article.

Abstract: A seal for effecting a seal between two components (2,4) to inhibit a flow of fluid, between the two components, in a sealing direction (22) from an upstream side (24) of the seal to a downstream side (26) of the seal. The downstream side (26) of the seal in use being at a lower pressure than the upstream side (26) of the seal. The seal comprising a carrier (12) adapted for mounting from one of the components (4), and a plurality of densely packed resilient strips (6) mounted on the carrier (12) to extend therefrom. Each strip (6) having a tip (20) which is adapted to wipe on the other component (2) to effect a seal thereagainst in the sealing direction (22) with the strips (6) arranged substantially parallel to the sealing direction (22). The seal being characterized in that there is provided a gap (30) between adjacent strips to allow the tip portions (20) of the strips (6) to move relative to each other and maintain in use a flexible seal.