Abstract: The invention relates to a packing structure (1) for a fluid exchange column, the packing structure defining an exchange surface for at least one down-flowing liquid phase that is to be put into intimate contact with at least one up-flowing gas phase, the structure including a volume formed by a plurality of rows of bundles of tubes (10), each bundle having four tubes (10a-10d) respectively oriented along four directions (D10a-D10d) forming an angle relative to the axis of the structure, the plurality of tubes forming a plurality of passages opening out to the outside surface of the structure (1).

Abstract: A method of manufacturing a part out of impervious thermostructural composite material, the method comprising forming a porous substrate from at least one fiber reinforcement made of refractory fibers, and densifying the reinforcement by a first phase of carbon and by a second phase of silicon carbide. The method then continues by impregnating the porous substrate with a composition based on molten silicon so as to fill in the pores of the substrate.

Abstract: A woven fibrous structure embodied in one piece, used for producing a composite material part and comprising an internal part or a core (72) and a part adjacent to the external surface thereof or a skin (74, 76), is formed by three-dimensional core weaving with at least one weave selected from interlock and multilayer weaves and by skin weaving with a weave which differs from the core weave and selected from a multilayer weave and a two-dimensional weave. It can be also formed by three-dimensional weaving with at least one core interlock weave (72) and weaving with a fabric-, satin or skin twill-type weave, wherein skin weaving is of a multilayer or two-dimensional type.

Abstract: A fiber structure for forming the reinforcement of a part to be made is placed in a mold (22) having at least one wall formed by a flexible membrane, and then a resin composition is injected into the mold, the composition having a volatile material content of less than 25% by weight and being at a temperature of a value such that its viscosity lies in the range 0.1 Pa·s to 0.3 Pa·s. The resin is polymerized in the mold placed in an enclosure (20) with temperature being raised progressively and with polymerization including at least a final stage of polymerization under pressure in order to obtain a composite material part presenting residual porosity of less than 11% by volume.

Abstract: The invention relates to a mixer (100) for a separate-stream nozzle of a turbojet, the mixer being designed to mix a hot inner stream from the combustion chamber of the turbojet with a cold outer stream from the fan of the turbojet. The mixer comprises an inner shroud (120) defining a flow channel for said hot inner stream, an outer shroud (110) disposed around the inner shroud (120) and co-operating therewith to define a flow channel for said cold outer stream, and a lobed structure (130) having lobes (1321, 1322) extending longitudinally from the trailing edges (110a, 120a) of said shrouds. The lobed structure (130) is made of a ceramic matrix composite material and is attached to the outer shroud (110) by flexible fastener tabs (140).

Abstract: A turbine ring assembly for a gas turbine, the assembly comprising a complete ring (10) forming a single piece of ceramic matrix composite material (CMC), a metal structure for supporting the CMC ring having metal annular supports (20, 30) between which the CMC ring is placed while allowing differential expansion at least in a radial direction between the CMC ring and the annular supports, means (40-42) for centering the CMC ring, and at least one element for preventing turning of the CMC ring about its axis.

Abstract: In order to assembly together two parts (154, 162) of materials having different coefficients of expansion vis mutually engaged edge portions (154a, 162a), tongues (170) are formed in the thinned edge of one of the parts, the tongues being separated by slots (172) obtained by cutting or machining the material of the part, and the parts are assembled together by fastening (174) via the tongues. The edge portions are mutually engaged in such a manner as to be in substantially leaktight contact at the high temperatures encountered in operation. The invention is applicable in particular to assembling together parts made respectively of metal and of ceramic composite material, in particular in an aviation gas turbine, e.g. upstream and downstream secondary nozzles.

Abstract: A turbine ring assembly for a gas turbine comprises a one-piece split ring (10) of ceramic matrix composite (CMC) material, a CMC wedge-shaped part (20) having flanks in contact with the ends of the ring, on either side of the split, so as to close the ring, and an annular metal support structure (40) surrounding the CMC ring and in contact therewith over the major fraction of its outline, the CMC ring being mounted with prestress in the metal structure, at least one element (26) exerting a resilient return force on the wedge-shaped part to keep it in contact with the ends of the CMC ring when the split opens under the effect of differential expansion between the annular metal structure and the CMC ring, and at least one element for preventing the CMC ring from turning about its axis.

Abstract: The invention relates to a method of fabricating a composite material part comprising fiber reinforcement densified by a matrix, the method comprising the steps of: making a fiber preform consolidated by impregnating (S4) a fiber texture made up of yarns with a liquid consolidation composition containing a precursor for a consolidating material, and by transforming (S7) the precursor into consolidating material by pyrolysis so as to obtain a consolidated preform that is held in shape; and densifying (S8) the consolidated fiber preform by chemical vapor infiltration; the method being characterized in that it includes, prior to impregnation (S4) of the fiber texture with the consolidation liquid composition, a step of filling (S2) the pores of the yarns of said fiber texture by means of a filler composition.

Abstract: A method of densifying porous substrates by chemical vapor infiltration comprises loading porous substrates for densification in a loading zone of an enclosure (10), heating the internal volume of the enclosure, and introducing a reagent gas into the enclosure though an inlet situated at one end of the enclosure. Before coming into contact with substrates (20) situated in the loading zone, the reagent gas admitted into the enclosure is preheated, at least in part, by passing along a duct (30) connected to the gas inlet and extending through the loading zone, the duct being raised to the temperature inside the enclosure, and the preheated reagent gas is distributed in the loading zone through one or more openings (33) formed in the side wall (32) of the duct, along the duct.

Abstract: A mixer for a separate-stream turbojet nozzle, the mixer comprising along a longitudinal axis (X-X?) both a fastener shroud (10) for connecting said mixer to the exhaust casing of the nozzle, and a lobe structure (20) presenting a succession of inner and outer lobes (22 and 21) distributed circumferentially around the longitudinal axis (X-X?) of the mixer. The lobe structure (20) is made of a ceramic matrix composite material and further comprises a stiffener ring (30) that forms a connection between at least some of the lobes of said structure. Thus, the major portion of the mixer, i.e. the lobe structure, is made of a ceramic matrix composite material, thereby significantly reducing the weight of the mixer, and consequently reducing the weight of the nozzle.

Abstract: A gas generator comprises a casing forming a ring or a ring portion and housing a pyrotechnic charge, the casing including at least one vent for ejecting the gas produced during combustion of the charge. Because of its ring design, the gas generator is easy to integrate in the structure of a rotary machine. In particular, it can constitute a starter device for a turbojet.

Abstract: The method comprises: using chemical vapor infiltration to form a first continuous interphase on the fibers of a fiber structure made of refractory fibers, the interphase having a thickness of no more than 100 nanometers; impregnating the fiber structure with a consolidation composition comprising a carbon or ceramic precursor resin; forming a fiber preform that is consolidated by shaping the impregnated fiber structure and using pyrolysis to transform the resin into a discontinuous solid residue of carbon or ceramic; using chemical vapor infiltration to form a second continuous interphase layer; and densifying the preform with a refractory matrix. This preserves the capacity of the fiber structure to deform so as to enable a fiber preform to be obtained that is of complex shape, while nevertheless guaranteeing the presence of a continuous interphase between the fibers and the matrix.

Abstract: A method of fabricating a lobed structure for a gas turbine flow mixer having an annular upstream portion extended downstream by a portion forming a multilobed skirt, the method comprising: making a fiber preform (100) out of refractory fibers and having a shape corresponding to the shape of the lobed structure to be fabricated, from a plurality of component elements of fiber texture that are assembled together and shaped by means of tooling of a shape corresponding to the shape of the lobed structure to be fabricated so as to obtain an assembled fiber preform having a first preform portion (111) corresponding to the annular portion of the lobed structure and a second preform portion (112) corresponding to the multilobed skirt of the lobed structure, the component elements of the fiber preform being assembled together at least in part along connection lines (121) extending substantially in the flow direction of the flow past the lobes of the multilobed skirt preform portion; and densifying the assembled an

Abstract: The method comprises the steps of: forming a porous fiber-reinforcing structure; introducing into the pores of the fiber structure powders containing elements for constituting the composite material matrix; and forming at least a main fraction of the matrix from said powders by causing a reaction to take place between said powders or between at least a portion of said powders and at least one delivered additional element; the powders introduced into the fiber structure and the delivered additional element(s) comprising elements that form at least one healing discontinuous matrix phase including a boron compound and at least one discontinuous matrix phase including a crack-deflecting compound of lamellar structure. At least a main fraction of the matrix is formed by chemical reaction between the powders introduced into the fiber structure and at least one delivered additional element, or by sintering the powders.

Abstract: An environmental barrier for a substrate of ceramic matrix composite material containing silicon, in particular containing SiC, is formed by an anticorrosion protection layer containing an aluminosilicate type compound of an alkali or alkaline-earth or rare earth element, e.g. BSAS, with a chemical barrier forming layer of aluminum nitride being interposed between the substrate and the anticorrosion protection layer.

Abstract: The invention relates to a yaw control device for an aircraft fitted with a supersonic nozzle having a rectangular or flat section comprising a supersonic throat extended by a diverging portion in which supersonic flow occurs. In order to enable the aircraft to be controlled in yaw in the absence of a vertical fin, the device of the invention makes use of jet control surfaces in the form of airfoils disposed in the diverging portion of the nozzle. The control surfaces are movable about respective pivot axes in order to generate a lateral force when in a deflected position, so as to enable the aircraft to turn about its yaw axis.

Abstract: The invention relates to a thermal erosion test device for testing thermal protection materials for use in a solid propellant thruster. The device comprises a support for holding a plate made of the thermal protection material for testing so that its faces a face of a block of solid propellant, the space between the plate and the face of the propellant block defining a combustion chamber of substantially rectangular shape, said chamber extending along said plate and opening out into a nozzle.

Abstract: A fiber reinforcing texture (10) woven as a single part for fabricating a composite material part having an inner portion (12), or core, made by three-dimensional weaving with yarns made up from discontinuous fibers, and a portion (14, 16) adjacent to an outside surface, or skin, made by weaving with yarns made up from continuous filaments.

Abstract: The invention relates to a heat treatment oven comprising a loading or treatment zone, at least one gas inlet, a gas preheater chamber situated in the oven between the gas inlet and the loading or treatment zone, a susceptor comprising at least a side wall surrounding the preheater chamber and the loading or treatment zone, and a field winding suitable for heating the side wall by induction. The portion of the side wall of the susceptor that is situated around the preheater chamber presents at least two recesses spaced apart circumferentially from one another so as to form portions of reduced thickness in said portion of the side wall.