Abstract: A combustion chamber assembly comprises a plurality of three stage lean burn combustion chambers (28) each of which comprises a primary combustion zone (36), a secondary combustion zone (40) and a tertiary combustion zone (44). Each of the combustion zones (36,40,44) is supplied with premixed fuel and air by respective fuel and air mixing ducts (76,78,80,92). A plurality of transition ducts (118) are provided at the downstream ends of the combustion chambers (28) to receive the exhaust gases. A damping ring (130) is connected to all of the transition ducts (118) by bolts (138) which pass through apertures (128) in flanges (126) on the transition ducts (118). The bolts (138) are biased by springs (142) such that frictional contact between the damping ring (130) and the flanges (126) damps harmful vibrations in the transition ducts (118).

Abstract: An improved process for providing hydrogen from an electrolytic cell having an anolyte solution having an anolyte liquid level; a catholyte solution having a catholyte liquid level; generating oxygen at an oxygen pressure above the anolyte level; generating hydrogen at a hydrogen pressure above the catholyte level; the improvement comprising detecting at least one of the anolyte and the catholyte liquid levels as anolyte level and catholyte level data; feeding the level data to central processing means; determining the pressure differential between the levels from the level data, and pressure adjustment data by the central processing means; and providing the adjustment data to pressure control means to maintain the pressure differential within a selected range. The process offers a low cost method of controlling the pressure differential to within 2 cm WC of a set point.

Abstract: A dual mode spreader includes a wheel supported container having a bottom wall provided with discharge openings feeding to a rotationally supported spreader disk; a skirt is mounted relative to the container to be movable to alter the distribution pattern between a broadcast mode and a drop mode; a mode determining member is provided to move with respect to the container in coordination with movement of the skirt between the broadcast and drop modes of operation.

Abstract: A superconductor is placed inside a non-metallic cryostat filled with a cooling medium to maintain the superconductor in a superconductive state. A foil winding is connected in series with the superconductor by current leads and the cryostat is placed inside the winding. The winding has only a few turns in order to provide low inductance and low magnetic field when the superconductor is carrying its normal operating current. However in the event of a fault the increase in electrical current in the line winding causes a magnetic field to be generated parallel to the superconductor. The magnetic field generated exceeds the critical magnetic field of the superconductor. The magnetic field produced by the line winding triggers the superconductor to the resistive state.

Abstract: A new nickel base superalloy suitable for compressor or turbine discs of gas turbine engines with fatigue crack propagation resistance equal to Waspaloy, tensile strength higher than Waspaloy and higher operating temperature than Waspaloy or UDIMET 720 family of alloys. The nickel base superalloy has a preferred composition by weight % of 14.0-19.0% cobalt, 14.35-15.15 Chromium, 4.25-5.25 Molybdenum, 1.35-2.15 tantalum, 3.45-4.15 titanium, 2.85-3.15 aluminium, 0.01-0.025 boron, 0.012-0.033 carbon, 0.05-0.07 zirconium, 0.5-1.0 hafnium, up to 1.0 rhenium, up to 2.0 tungsten, less than 0.5 niobium, up to 0.1 yttrium, up to 0.1 vanadium, up to 1.0 iron, up to 0.2 silicon, up to 0.15 manganese and balance nickel plus incidental impurities.

Abstract: In a gas turbine engine, the exit end of a combustion chamber of annular shape is suspended from the interior wall of the engine casing by an elbow structure which is detachably mounted on a flange by one of its two legs; the resilience of the elbow structure is improved by dove-tail shaped openings provided in the elbow structure with the narrowest section of the openings facing the bend line of the elbow structure to define with the opening of the other leg a gap that enables the elbow structure to function as a leaf-spring.

Abstract: A laser beam delivery apparatus and a method for smoothly and uniformly ablating tissue, e.g., for reshaping a cornea of an eye, even in the face of real-world conditions such as a moving eye. The method includes defining a plurality of scan lines in an ablation zone on the tissue and defining a plurality of laser beam ablation points along each of the scan lines. An ablating laser beam is scanned along a series of non-adjacent scan lines of the plurality of scan lines and tissue is intermittently ablated at non-adjacent ones of the laser beam ablation points on each non-adjacent scan line of the series of non-adjacent scan lines.

Abstract: A wax pattern assembly (10) is removed from a ceramic shell mould (30) by removing a support member (20) from the wax pattern assembly (10). The ceramic shell mould (30) is then heated to melt the wax out of the ceramic shell mould (30). The removal of the support member (20) provides a cavity (22) into which the wax may expand without cracking the ceramic shell mould (30). The support member (20) is provided with an external thread to allow it to be easily removed from the wax pattern assembly (10).

Abstract: The twin chopper of the present invention consists of a pair of roving choppers, each chopper being disposed on either side of a resin spraying nozzle. Each chopper comprises a rotatably driven cutter roller, a rotatable friction roller cooperating with the cutter roller, and an idler roller cooperating with the friction roller for feeding roving strands between the friction roller and the cutter roller. The outlet of the first chopper is so disposed relative to the nozzle as to discharge cut rovings over and onto the flat spray of resin while the outlet of the second chopper is so disposed relative to the nozzle as to discharge cut rovings under and onto the flat spray so that the resin spray is coated with roving cuts on both sides thereof from both choppers as the spray is directed onto the open mold surface.

Abstract: An annular seal is provided between a turbine rotor disc and the adjacent static structure. The seal comprises rotor fins extending from the turbine disc for rotation therewith and an abradable honeycomb layer radially outward of the rotor fins. The abradable honeycomb layer is located on the inner diameter of a sealing ring attached to the static structure. The sealing ring is moveable in an axial direction so that in operation the honeycomb has one axial position for transient conditions and an alternative axial position for stabilized running. The seal clearance can thus be optimised at the two axial positions reducing the leakage flow through the seal.

Abstract: An annular heat exchanger suitable for a gas turbine engine includes a first continuous sheet of material arranged in a spiral and a second continuous sheet of material arranged in a spiral. A first axially extending passage is defined between the first surface of the first sheet and the third surface of the second sheet and a second axially extending passage is defined between the second surface of the first sheet and the fourth surface of the second sheet. The first passage is closed at its axial ends by spiral seals between the first sheet and the second sheet. The second passage is open at its axial ends. A plurality of radially extending passages are provided to supply a first fluid at a first end into the first passage, to remove the first fluid from a second end of the first passage and to interconnect adjacent turns of the first passage. The passages extend radially through the second passage.

Abstract: The present invention relates to a digester for continuous cooking under raised pressure and temperature of fibre material in a vertical digester (1), where input of fibre material and cooking liquid takes place at the top of the digester, withdrawal of spent cooking liquor is carried out from at least one digester screening arrangement (1D) between the top and the bottom of the digester, and fibre material is fed out from the bottom (1C) of the digester, wherein the digester (1) is fitted with an additional digester screening arrangement (2) above the lowest screening arrangement (1B) of the digester so that the temperature in all the participatory cooking zones in the digester can be kept at essentially the same temperature level.

Abstract: Process for recovering chemicals and energy from black liquor, where the black liquor is gasified with CO, CO.sub.2, CH.sub.4, H.sub.2, and H.sub.2 S, in gaseous form, and Na.sub.2 CO.sub.3, NaOH and Na.sub.2 S, in the form of drops of smelt, being principally formed. The mixture of gas and smelt is cooled, in a first stage, by direct contact with a cooling liquid, whereupon a part of the cooling liquid is volatilized, and the smelt drops are separated off and dissolved in the remaining part of the cooling liquid with the formation of a liquid bath of green liquor. In a second stage, the gas is washed and saturated with moisture by direct contact with a washing liquid bath. After the gas has been washed in the second stage, energy in the form of thermal energy and condensation heat is recovered from the gas in an indirect condenser.

Abstract: A ducted fan gas turbine engine (10) is provided with a fan (12) which is carried by a shaft (16). A frangible support member (27) maintains a coaxial relationship between the shaft (16) and the longitudinal axis (15) of the engine (10). In the event of severe damage to the fan (12), the frangible member (27) fractures, allowing the shaft (16) carrying the fan (12) to orbit about the engine longitudinal axis (15). A resilient support member (33,45) exerts a radially inward restoration force on the shaft (16) carrying the fan (12) to reduce vibration.

Abstract: A gas turbine engine combustion chamber comprises a primary combustion zone and a secondary combustion zone downstream of the primary combustion zone. A catalytic combustion zone is arranged downstream of the secondary combustion zone and a homogeneous combustion zone is arranged downstream of the catalytic combustion zone. A pilot injector supplies fuel into the primary combustion zone. At least one primary premixing duct has a plurality of primary fuel injectors to supply a first mixture of fuel and air into the primary combustion zone. A secondary premixing duct has a plurality of secondary fuel injectors to supply a second mixture of fuel and air into the secondary combustion zone. A plurality of temperature sensors are arranged at the intake to the catalytic combustion zone and a processor controls the valves which adjust the supply of fuel the fuel injectors to ensure that the temperature at the intake to the catalytic combustion zone remains in a predetermined temperature range.

Abstract: A ducted fan gas turbine has a fan shaft which is supported at its upstream end by a bearing. In the event of damage to the engine's fan, frangible bolts fracture to permit radial movement of the shaft. That movement is limited by the sequential engagement of the outer race of the bearing with first and second movement limiting portions on fixed structure of the engine. This alters the natural frequency of vibration of the fan, so permitting the fan to windmill without excessive vibration.

Abstract: A gas turbine engine has an assembly of circumferentially spaced rotor blades each having a radial tip. A plurality of seal segments mounted for radial movement circumscribe the rotor blades. Each segment is connected to the casing through a seal carrier provided with a flexible membrane which divides high pressure air from low pressure into two channels.

Abstract: A stator vane assembly for a gas turbine engine (10) compressor (16) comprises a plurality of circumferentially arranged stator vanes (44A) and a plurality of circumferentially arranged load bearing struts (46). The leading edges (45,47) of the stator vanes (44A) and the struts (46) are arranged in a common plane. The leading edges (45,47) of the stator vanes (44A) and the struts (46) have substantially the same profile. The spacing (B) between adjacent struts (44A) in any group is the same.