Abstract: A process for producing a coating for protecting superalloy articles against high temperature oxidation and hot corrosion comprises forming, on the surface of the article, a first deposit of an agglomerated powdered alloy containing at least chromium, aluminum and an active element, and filling the open pores of the powder deposit by a second, electrolytically applied, deposit of a precious platinum group metal. An appropriate thermal treatment is then carried out to effect interdiffusion between the powder based deposit and the electrolytic deposit and produce a coating including chromium, an active element such as yttrium, and a precious platinum group metal throughout its thickness.

Abstract: An axially symmetric turbojet engine exhaust-nozzle includes a system for masking the exhaust jet, such system including inner hot flaps (7), hinging on a conical shell (4) and driven by a first control ring (10) powered by linear actuators (11), and outer cold flaps (20) hinging on an annular assembly (12) and driven by a second control ring (22) powered by linear actuators (23) to vary the angle of the cold flaps. The annular assembly (12) is axially displaceable by a third set of linear actuators (30). Each cold flap (20) comprises an inner skin (40) fitted with orifices (43) and hinging on the annular assembly(12) and an outer skin (41) spaced radially away of the inner skin (40) to define an air flow channel between the skins.

Abstract: A rear mixer ejector of a turbomachine for a supersonic aircraft has an ejector casing of rectangular cross-section fitted with movable flaps defining a variable geometry exhaust nozzle, and cold air mixing devices mounted on the casing side walls upstream of the nozzle. The mixing devices comprise a plurality of U-section chutes extending into the casing from apertures in the casing side walls, each chute being formed by a pair of lateral walls and a transverse wall disposed between them. The chutes are adjustable between a deployed position and an inoperative position, either by pivoting the chutes about axes at the downstream edges of the apertures or by pivoting only the transverse walls about the upstream edges of the apertures. In each case the lateral walls of the chutes remain in the gas flow path through the casing, parallel to the casing axis, in both the deployed and the inoperative positions, and the transverse walls are parallel to the casing axis in the inoperative position.

Abstract: The invention concerns a method for metal coating of fibres (15) by liquid process, said method being particularly but not exclusively designed for coating in thick and even layers (22) with metals and metal alloys having high melting point and reactivity. Said method is characterised in that it consists in moving along the stretched fibre (15) in the liquid metal maintained in levitation in a well (1), said fibre (15) passing through orifices (6, 7) provided in the well (1) wall (3), said orifices (6, 7) being arranged on either side of the liquid metal at places where the liquid metal (10) is not in contact with said wall (3).

Abstract: A gas-flow exhaust assembly for a jet propulsion system of an aircraft in which a converging exhaust nozzle (4) is fitted with translating cold flaps (21, 22). The primary exhaust nozzle (4) comprises two hot-flaps (5, 6) situated beyond a primary duct (1) enclosed by an aircraft fairing (2). The fairing (2) is extended by a secondary exhaust nozzle (20) which is supported by the primary duct (1) and which is translatable by a control mechanism (27a, 27b). The secondary exhaust nozzle (20) comprises cold flaps (21, 22) which are driven by another control mechanism (29a, 29b) independently of the angular positions of the hot flaps (5, 6). Preferably, there are two eyelid-shaped cold-flaps (21, 22) hinging and supported on horizontal transverse shafts (23a, 23b). The shafts (23a, 23b) are preferably affixed on two lateral slides (24a, 24b) which slide on the primary duct (1) and are displaceable by the control mechanism (27a, 27b) which translates the secondary exhaust nozzle (20).

Abstract: The housing is heated or cooled to adjust its diameter and, in particular, the play between the tips of the rotor blades and the housing. The apparatus consists of networks of tubes (1) covering complementary portions of the circumference of the housing and consisting of a pair of distributors (3) and parallel tubes (2) between said distributors, said tubes (2) being alternately connected to one or other of the distributors and provided with apertures to blow the gas onto the housing. The counter-flow circulation in the tubes (2) makes it possible to supply both gas that has been greatly heated by traveling a considerable distance through the tubes (2) and cooler gas that has traveled less far in other tubes (2) to any point on the housing, thereby balancing out the heat applied to every portion of the housing.

Abstract: A high bypass ratio turbojet engine comprising a fan rotated by the shaft of a low pressure turbine via a speed reducer is provided with a thrust reverser device by providing the speed reducer with first and second epicyclic gear trains which are mounted in parallel between the low pressure turbine and the fan and which are arranged in such a way as to drive the fan in a first direction of rotation when the engine is operated in a direct thrust mode, and to drive the fan in the opposite direction of rotation when the engine is to be operated in the reverse thrust mode.

Abstract: A coating (22) with a high coefficient of friction and low thermal conductivity covers a turbomachine low pressure shaft (12) in the vicinity (17) of a concentric high pressure shaft (11), in the area at which high friction contact between the two shafts could occur if a bearing (13) on the low pressure shaft (12) breaks following a failure causing the appearance of an out-of-balance mass. Friction would also more quickly equalize shaft speeds and reduce overheating in them.

Abstract: A high-strength hybrid component including a relatively soft first part made of a composite material including an organic matrix reinforced with fibers, a relatively hard second part made of metal, metal alloy, or ceramic, and a transition layer made of a composite material including a matrix of a material that is weldable to the hard part and fibers that are extensions of the fibers of the soft part. The transition layer matrix and the hard part may be formed by deposition of molten material on to the fiber preform of the soft part using flame, electric arc, or plasma. The resin matrix of the soft part is impregnated into the preform and polymerized afterwards. Alternatively, the hard part may be machined to shape and welded to the transition layer before completing the soft part.

Abstract: A titanium-based intermetallic alloy having a high yield stress, a high creep resistance and sufficient ductility at ambient temperature has the following chemical composition as measured in atomic percentages:Al, from 16 to 26; Nb, from 18 to 28; Mo, from 0 to 2; Si, from 0 to 0.8; Ta, from 0 to 2; Zr, from 0 to 2; and Ti as the balance to 100; with the condition that Mo+Si+Zr+Ta>0.4%.Production, working and heat-treatment ranges adapted to the intended use of the material are also defined.

Abstract: The particle trap (15) that extends behind an elbow in the air flow stream (6) in a turbo-prop engine is delimited at the back by an end plate (12) to which intake housing suspension rods (10) supporting the front of the rotating shaft (2), are fastened. It is divided by suspension arms (11) which may be drilled (21) to restore the continuity of the annular chamber forming the trap. Therefore the intake housing suspension device extends through the trap. This type of trap makes use of the inertia of solid bodies carried by the air drawn in, and which could damage the engine blades, and to collect them.

Abstract: A rectifier vane stage is connected to a stator that is supported at the internal end thereof by a connecting ring which includes a support ring and a stiffening ring, a retaining lip of which is inserted into the support ring and similarly into the recesses of the ends of the vanes. The possibility of the vane accidentally coming loose following breakage of said vane is therefore eliminated.

Abstract: A method of diffusion brazing parts made of a superalloy A uses a single-component brazing powder prepared by measuring a quantity of a superalloy powder having a composition identical to the superalloy A and a quantity of a boron and/or silicon flux powder in a proportion of between 0.1% and 40% by weight of the superalloy powder, mixing the powders and placing them with balls made of superalloy A in a container also made of superalloy A, closing the container and keeping its contents in a controlled atmosphere, placing the container in a grinder and operating the grinder to keep the container moving for a period ranging from 30 seconds to 500 hours in order to encrust the flux onto the surface of the grains of the superalloy powder.

Abstract: The invention relates to the control of air flows for cooling the axial walls of a high-temperature combustion chamber in which the walls are provided with through holes forming multiple perforations, and involves arranging the multiple perforations so that the cooling airflow permeability of the walls in the downstream zone of the chamber decreases in the downstream direction in order to compensate for the effects of the increase in pressure drop due to variation of the gas flow velocity. The invention is particularly applicable to sharply convergent combustion chambers such as twin-head combustion chambers.

Abstract: An afterburn device for a turbojet engine comprises a flame arrester formed by a plurality of radial arms distributed evenly around the rotational axis of the engine at the upstream end of the afterburn chamber. Each arm consists of a fixed rear part, and a front part which is separable from the rear part in a circumferential direction along a median joint plane, the front parts being carried on a ring which is rotatably mounted on the outer casing of the engine. Drive means is provided for rotating the ring between a first position for dry operation, and a second position for afterburn operation. In the first position the front and rear parts of the arms are aligned and joined to provide the arms with a streamlined, low-drag, zero angle of incidence profile suitable for dry operation.

Abstract: Two objects are articulated together by a strong and compact joint which provides two rotational degrees of freedom about axes X and Y, and which comprises a bearing have a male inner ring swivel mounted in a female outer ring. The male inner ring is rotatably mounted on a shaft integral with one of the objects and defining the axis X, and the female outer ring is attached to the other object. The two rings are rotationally linked in the direction of an axis Z perpendicular to the X and Y axes by two flat support surfaces on the inner ring arranged between two flat guide surfaces in the outer ring, the said support surfaces and the said guide surfaces being parallel to the X and Z axes.

Abstract: A soundproofing panel comprises a honeycomb core sandwiched between a solid skin and a porous skin, the cells of the honeycomb being divided in the direction of its thickness into at least two resonant cavities by a least one partition which is traversed by passages interlinking the cavities. The partitions are formed by a plurality of hollow microbeads having porous walls, the microbeads being bonded to one another and to the walls of the honeycomb at their points of contact. Such a soundproofing panel combines high performance in terms of linearity as a function of the level of sound excitation, attenuation band, bulk and mechanical strength.

Abstract: The invention proposes a process for bladder moulding thin articles made of a composite material consisting of fibre and polymerised resin, the articles comprising corners having a rounded vertex and produced by a shaper. Such a process is distinguished in that the surface experiencing the air pressure is convex and the normals to the surface converge on the rounded shaping vertex of the shaper.

Abstract: A constant-speed twin spool turboprop unit including a twin spool gas generator having a low-pressure spool and a high-pressure spool each including a compressor and a turbine which drives the compressor, is described in which at least one propeller of the unit is driven by at least the high-pressure spool of the gas generator.

Abstract: The system (13) for admitting external air (12) into a working section (11) of a gas turbine engine through a jacket (10) of the working section is characterised by the combination of doors (15) sliding towards the front (ramps) and rotating doors (14). The ramps (15) are fitted with grooved lateral arms (30) in which run wheels mounted on the doors (14). When they reach an ascending part (33) of the grooves (31) after sufficient movement of the ramps (15) towards the front, they are caused to rise, which opens the doors (14). This system can be used on double flow gas turbine engines for supersonic aircraft.