FR3018097B1 - TURBOMACHINE ORGAN COMPRISING A METAL PIECE AND A COMPOSITE MATERIAL PART - Google Patents

Abstract

Turbomachine member (156) having a first piece (158) of metal, a second piece (164) of composite material, and means (178) for fixing the first and second parts, characterized in that at least one seal ( 186) is interposed between the parts so that they are not directly in contact with each other in the mounting position, and in that the fixing means comprise at least one rivet (182) which is mounted in openings (188, 190) of the parts, and which is surrounded by a ring (184), this ring being clamped by the rivet against one of the parts and having a predetermined length according to a desired compression ratio the seal between the pieces.

Description

TECHNICAL AREA

The present invention relates to a member for a turbomachine, this member comprising a metal part and a composite material part, and means for fixing the first and second parts.

STATE OF THE ART

The following description refers to a particular member (discharge duct) of a turbomachine for which the invention is particularly suitable. The invention is however not limited to this particular application.

A turbomachine with a double flow comprises a flow vein of a primary flow or hot flow and a flow vein of a secondary flow or cold flow. It is known to equip such a turbomachine discharge valves, sometimes designated by their acronym VBV (Variable Bleed Valve).

Valves of this type are intended to regulate the flow of air inlet into the primary vein in particular to limit the risk of pumping the compressor of the turbomachine by allowing the evacuation or discharge of an air flow in the secondary vein. In addition, in case of accidental penetration into the primary vein, water, especially in the form of rain or hail, or various debris, which are likely to affect the operation of the turbomachine, these valves can recover this water or these debris that are centrifuged and routed to the secondary vein.

As can be seen in FIG. 2 of application FR-A1-2 982 904, a discharge duct may be mounted downstream of each discharge valve so as to guide the air to the secondary vein of the turbomachine. This discharge duct comprises a tubular sleeve for guiding the discharge air flow and a finned grille provided at one end of the outlet sleeve of the air flow. In the context of the present invention, the grid is carried exclusively by the sleeve, which is not the case in the aforementioned prior application because the gate is also carried by an intermediate casing.

The conduit sleeve is generally made of foundry. It is not conceivable to form the grid and the sleeve of a single piece of casting because the outlet end of the sleeve must be left free to allow any material reload operations of the inner wall of the sleeve. The grid is reported and fixed on the outlet end of the sleeve, after the manufacture of the latter.

It has been proposed to produce the grid and its fins in one piece made of composite material, so as to reduce the mass of this grid and to reinforce some of its mechanical properties.

However, the attachment of a piece of composite material (such as the gate of the discharge duct) on a metal piece (such as the sleeve of this duct) is not easy to implement, to achieve a member intended to be used in a turbomachine, in particular for the following reasons: - during the fixing operation, the composite material, relatively fragile, can be damaged, - the parts have different vibratory behaviors because of their different materials, resulting in in particular problems of frequency coupling; in operation, the vibrations of the metal part can be transmitted to the composite part and cause fatigue of the latter; in the case where the metal part resonates, significant vibrations would be transmitted to the composite part and could reduce its life, - the parts also have different thermal behavior, the differential thermal expansion can cause significant constraints in rooms.

The present invention provides a simple, effective and economical solution to this problem.

DESCRIPTION OF THE INVENTION The invention proposes a turbomachine member, comprising a first metal part, a second part made of composite material, and means for fixing the first and second parts, the first part comprising a first wall comprising at least a first part. orifice which is aligned with a second orifice of a second wall of the second part, for the passage of fastening means through said first and second orifices, characterized in that at least one seal is interposed between said first and second walls; so that the first and second parts are not directly in contact with each other in the mounting position, and in that the fastening means comprise at least one rivet which is mounted in said first and second orifices and which is surrounded by a ring, said ring passing through said second orifice and being, in the mounting position, held tight by the rivet against said first wall, said ring having a predetermined length as a function of a desired compression ratio of the joint between said first and second walls.

The seal is interposed between the parts to prevent them from being in direct contact and thus to prevent the vibrations to which one of the parts is subjected in operation, to be transmitted to the other part. The seal thus makes it possible to decouple the frequencies between the parts. It also makes it possible to soften the riveted connection between the parts and to reduce the vibration problems of the rivets in operation.

The ring that surrounds the rivet is held tight between the rivet and the metal piece. It is therefore intended to withstand the forces during the installation of the rivet, and in particular during its crimping. The composite material of the second part is thus protected and will not be damaged during this operation. Furthermore, the ring has a predetermined length depending on the desired rate of compression or crushing of the seal between the parts. This is particularly advantageous because it allows to precisely control the compression of the seal, its compression ratio being defined so that it optimally ensures its function of insulating parts. In addition, this type of ring may have a relatively small diameter, the metal-to-metal support is limited, which limits the risk of transmission of vibratory modes between the parts.

Advantageously, the ring comprises at one end an outer annular flange. This collar is preferably interposed between a rivet head and said second wall. This collar makes it possible to increase the bearing surface on the second wall and to better distribute the crimping forces of the rivet on the second part, and thus to limit the risks of degradation of its composite material.

The rivet may comprise another head which is, in the mounting position, bearing on said first wall.

The seal is preferably planar. The seal preferably includes an orifice aligned with said first and second ports. This hole is thus intended to be crossed by the rivet.

The seal is preferably made of elastically deformable material, for example silicone.

The ring may be made of metal material, such as steel.

According to a particular embodiment of the invention, the member is a discharge conduit. This discharge duct comprises a tubular sleeve for guiding an air flow and a finned grille mounted at an outlet end of the sleeve. The sleeve is metallic and forms said first piece, and the finned grid is made of composite material and forms said second piece.

The present invention also relates to a turbomachine, characterized in that it comprises at least one member as described above.

The present invention also relates to a method for producing a turbomachine member, by fixing a first metal part to a second part made of composite material, the first part comprising a first wall comprising at least a first orifice which is intended to be aligned with a second orifice of a second wall of the second part, for the passage of fastening means through said first and second orifices, characterized in that it comprises the steps of: - inserting at least one joint between said first and second walls, so that the first and second parts are not directly in contact with each other in the mounting position, - mounting at least one rivet in said first and second orifices, a ring being previously mounted around the rivet and being intended to pass through said second orifice, and - crimp the rivet, so that the ring is held tight by the rivet against said first wall, said ring having a predetermined length as a function of a desired compression ratio of the joint between said first and second walls.

DESCRIPTION OF THE FIGURES The invention will be better understood and other details, characteristics and advantages of the invention will emerge more clearly on reading the following description given by way of nonlimiting example and with reference to the appended drawings in which: FIG. 1 is a diagrammatic view in axial section of a turbomachine with a double flow, FIG. 2 is a partial diagrammatic view in axial section and on a larger scale of a turbomachine, FIG. 3 is a diagrammatic perspective view. of a discharge duct according to the invention, and - Figure 4 is a schematic sectional view of a portion of the discharge duct of Figure 3.

DETAILED DESCRIPTION

As is shown in FIG. 1 which is a diagrammatic view in axial section of a double-body turbojet engine 10, such a turbojet engine generally comprises, from upstream to downstream in the direction of flow of the gases, a compressor low pressure 12, a high pressure compressor 14, a combustion chamber 16, a high pressure turbine 18 and a low pressure turbine 20, which define a primary flow of gas 22.

The high pressure turbine 18 is secured to the high pressure compressor 14 so as to form a high pressure body, while the low pressure turbine 20 is secured to the low pressure compressor 12 so as to form a low pressure body, so that each turbine drives the compressor associated in rotation about a turbojet axis 24 under the effect of the thrust of the gases from the combustion chamber 16.

An intermediate casing 26 is usually interposed between the low pressure compressor 12 and the high pressure compressor 14.

In the case of turbofan engines, which comprise a fan 28 streamlined by a nacelle 30 for generating a secondary flow 32, the intermediate casing 26 generally comprises arms 34 passing through the flow passage of this secondary flow 32.

Figure 2 illustrates on a larger scale the hub 36 of the intermediate casing 26 of a known type of turbojet similar to that described above. This hub 36 comprises an inner shell 38 defining the flow space of the primary flow 22, an upstream cheek 40 and a downstream cheek 42 connected to the aforementioned inner ferrule 38, and an outer ferrule 44 connecting said cheeks 40, 42 .

The hub 36 supports intermediate case arms 34 fixed to the radially outer ends of the flanges 40 and 42. Moreover, this hub 36 is equipped with an annular row of discharge valves 48, one of which is visible in section on the FIG. 2. This figure more specifically shows the door 50 of the valve 48, which is pivotally mounted about an axis 51, so as to be movable between an open position and a closed position of a corresponding orifice formed in the inner shell 38 of the hub 36.

For the control of the discharge valves 48, the control mechanisms usually used are either control ring mechanisms or torsion cable mechanisms. The opening of each valve 48 causes the discharge of an air flow (arrow 52 in dotted lines) in the annular space defined by the rings 38, 44 and the flanges 40, 42.

The downstream cheek 42 comprises an annular row of orifices 54 for passage of the discharge air streams 52, downstream. As seen in FIG. 2, discharge ducts 56 are mounted downstream of the intermediate casing 26 and are each intended to guide an air flow 52 caused by the opening of a discharge valve 48, the flow of air air being guided from the outlet of the orifices 54 to the flow vein of the secondary flow 32.

Each discharge duct 56 comprises a tubular sleeve 58 for guiding the air flow 52, an upstream or inlet end 60 of which is fixed on the downstream face of the cheek 42, so that this end is aligned with the one of the orifices 54, and a downstream or outlet end 62 is fixed to the intermediate casing 26.

The sleeve 58 of the duct 56 here has a shape bent at 90 °, its upstream end being oriented substantially axially upstream and its downstream end being oriented radially outwardly with respect to the axis 24 of the turbojet engine.

A finned grid 64 is mounted at the outlet of the duct 56 and is here fixed to a shell 39 (FIG. 2) defining internally the flow vein of the secondary flow 32.

FIG. 3 represents an exemplary embodiment of a discharge duct 156 according to the invention. Essentially, the conduit 156 comprises two elements: a tubular sleeve 158 for guiding a discharge air flow, and a finned grille 164 which is attached and fixed to the downstream or outlet end 162 of the sleeve 158.

The sleeve 158 here has in section a substantially rectangular or square shape whose corners are rounded. The inlet end 160 and outlet end 162 of the sleeve thus have a generally rectangular or square shape.

The sleeve 158 has at each of its ends 160, 162, an annular flange 166 for fixing, which extends around the entire periphery of the corresponding end. Each flange 166 comprises through-holes for the passage of fastening means, of the screw-nut type for example.

The flange 166 for fixing the inlet end 160 of the sleeve 158 is configured to be applied for example on the downstream face of the downstream flange (referenced 42 in FIG. 2) of an intermediate casing of a turbomachine equipped with the The fixing flange 166 of the outlet end 162 of the sleeve 158 is configured to be applied, for example, to the radially inner face of a wall of revolution intended to internally delimit the flow channel of the secondary flow. the turbomachine.

The sleeve 158 is metallic and can be made of foundry. It is for example titanium.

The gate 164 comprises fins 168 and means 170 for supporting and fixing the outlet end 162 of the sleeve 158. The number of fins is between two and five.

The fins 168 are here three in number and are substantially identical. They are substantially parallel to each other and spaced apart from each other. Each fin 168 has an elongated shape and an aerodynamic profile. It can be likened to a blade having a lower surface and an upper surface, which are interconnected by an upstream leading edge and a downstream trailing edge of the discharge air stream. In the mounting position shown in the drawings, the lower and upper surfaces of the fins form an angle of between approximately 25 ° and 40 °, relative to the direction of the discharge air flow at the outlet of the duct 156.

In the example shown, the fins 168 are formed in one piece with the support means 170 and are therefore fixed relative thereto. The support means 170 comprise a first support means 170a connected to first longitudinal ends of the fins 168, and a second support means 170b connected to second longitudinal ends of the fins 168 (opposite their first ends).

The first and second support means 170a, 170b each have an elongate shape and are here substantially parallel. They extend along two opposite (eg side) sides of the outlet end 162 of the sleeve, only a portion of the length of these sides. They are substantially located in the middle of these sides and are located at distances from the other sides (for example lower and upper) of the end 162. They are substantially perpendicular to the fins 168.

Each support means 170a, 170b is formed by a substantially L-shaped section bar, this bar comprising a first wall 172 intended to be applied and fixed on the end 162 of the sleeve 158, and in particular on a bottom wall of a flange of the flange 166 of this end 162, and a second wall 174 of connection to the fins 168 and which is substantially perpendicular to the first wall 172. The first walls 172 of the support means 170a, 170b are parallel and coplanar, and their second walls 174 are parallel. These second walls 174 comprise facing faces between which the fins 168 extend. The walls 172, 174 of the same support means 170a, 170b are interconnected by transverse reinforcement ribs 176, which are spaced apart one after the other. others and regularly distributed along the support means 170a, 170b.

In the mounting position, the walls 174 of the support means 170a, 170b extend in the extension of internal walls of the sleeve 158, so as to limit the aerodynamic disturbances at the outlet of the conduit 156. Moreover, the free longitudinal edges of the walls 174 are aligned with peripheral edge portions 177 of the outlet end 162 of the sleeve 158.

The gate 164 is fixed to the sleeve 158 by fastening means 178. For this, the walls 172 of the support means 170a, 170b may comprise orifices aligned with corresponding orifices of the flange 166 of the outlet end 162 of FIG. the sleeve, for the passage of the fastening means 178.

The gate 164 is made of a single piece of composite material, loaded for example with carbon fibers.

The present invention provides particular means to ensure the attachment of the gate 164 on the sleeve 158, and generally to ensure the attachment of a composite material part on a metal part.

FIG. 4 shows an embodiment of the invention, in the particular case mentioned above where the metal part is the sleeve 158 of a discharge duct 156 and the composite part is the finned grille 164 of this duct.

FIG. 4 is a cross-sectional view, on a large scale, of one of the support means 170 of the grid 164, and of part of the flange 166 of the sleeve 158. The constituent elements of this means of support 170 such that its substantially L-section bar having the first wall 172 to be fixed on the bottom wall 180 of the groove of the flange 166, and the second wall 174 of connection to the fins 168 of the grid 164. The walls 172, 174 are interconnected by the transverse reinforcement ribs 176.

The means 178 for fixing the grid 164 to the sleeve 158 essentially comprise two elements: a rivet 182 and a ring 184, the fastening means 178 being further associated with at least one seal 186.

The rivet 182 of each fastening means 178 passes through an orifice 188 of the wall 172 of the grid 164 and an orifice 190 of the wall 180 of the sleeve 158, these orifices 188, 190 being substantially aligned before the rivet 182 is laid.

The rivet 182 comprises a head 192, 194 at each of its ends. A first head 192 of the rivet 182 bears axially on one face of the wall 180, this face being oriented on the opposite side to the gate 164. The second head 194 of the rivet bears axially against the ring 184, and in particular on an outer annular collar 196 located at one end of this ring 184. The head 194 of the rivet 182 is supported on one face of this collar 196, located on the side opposite the sleeve 158. The collar 196 is supported by its other face (that located on the side of the sleeve 158) on the wall 172 of the gate 164, and in particular on its face located on the opposite side to the sleeve 158.

The ring 184 has a generally tubular shape with cylindrical internal and external contours. It surrounds rivet 182 and extends over most of its length. It is configured to pass through port 188 of wall 172 only. It thus has an external diameter less than the internal diameter of the orifice 188. Its flange 196, however, has an outer diameter greater than the diameter of the orifice 188. The orifice 190 of the wall 180 has an internal diameter smaller than the external diameter of the ring 184 which is not intended to cross this orifice 190. The inner diameter of this orifice 190 is slightly greater than the outer diameter of the rivet 182 to allow the passage of the rivet in this orifice 190. The end of the ring 184 , opposed to its flange 196, is intended to bear on the wall 180, and in particular on the face of this wall located on the side of the grid 194, as shown in the drawing.

The seal 186 is flat and interposed between the walls 172, 180, that is to say between the facing faces of these walls. It comprises at least one orifice 198 for passage of the ring 184 and the rivet 182. The internal diameter of this orifice 198 is thus greater than the external diameter of the ring 184.

When crimping the rivet, the seal 186 crushes between the walls 172, 180. According to the invention, the compression ratio of the seal 186 is controlled and predetermined.

For this, the ring 184 is held tight by the rivet 182 against the wall 180 and this ring 184 has a predetermined length. More specifically, the axial distance L between the face of the flange 196, located on the side of the sleeve 158, and the end of the ring 184 opposite the flange 196, is equal to the cumulative thicknesses after crimping the wall 172 (thickness e1) and the seal 186 (thickness e2). In the case where the seal 186 has, before crimping (that is to say in the uncompressed state, without stress), an initial thickness e2 ', the compression ratio of the seal 186 after crimping is defined as k ( %) = (1 - e2 / e2 ') * 100.

For example, if the seal has an initial thickness e2 'of 1.2mm and a thickness e2 after compression of 1mm, its compression ratio is k = (1 -1 / 1.2) * 100 = 17%. In the case where the wall 172 of the grid 164 has a thickness of 3mm, the distance L of the ring 184 must be 3mm + 1mm = 4mm. In the case where the flange 196 of the ring has a thickness of 1 mm, this ring 184 has a total length of 4 mm + 1 mm = 5 mm.

As can be seen in the drawing, the flange 196 of the ring 184 may comprise an annular groove 200 at the inner periphery of its face bearing on the wall 172.

The fastening means 178 of the grid 164 to the sleeve 158 comprise as many rings 184 as rivets 182, the rivets being four in the example of Figure 3. Each support means 170a, 170b of the grid 164 is fixed to the sleeve 158 by two fastening means 178, each fastening means 178 being housed between two adjacent reinforcing ribs 178.

Each fastening means 178 may be associated with a gasket 186 independent of the gasket of the other fastening means 178. Alternatively and preferably, each support means 170a, 170b is associated with a gasket 186 which is independent of the gasket of the gasket. other support means 170b, 170a.

Each seal 186 then has an elongated shape and extends longitudinally between the walls 172, 180, over substantially the entire length thereof. This seal 186 then comprises the two orifices 198 for passage of rivets 182 for fixing the corresponding support means 170a, 170b.

The ring 184 is preferably metal, and for example titanium, and the seal 186 is preferably of elastically deformable material, for example silicone.

In an alternative embodiment of the invention not shown, the support means 170 of a fin 168 could be independent of the support means of the other fins 168. It would thus be possible for each of the first and second support means 170a, 170b is formed of three independent parts of each other (as schematically represented by the dashed lines in Figure 3), and independently fixed on the downstream end 162 of the sleeve 158.

Claims (10)

1. A turbomaGhine member (156) having a first piece (158) of metal, a second piece (164) of composite material, and means (178) for fixing the first and second pieces, the first piece having a first wall ( 180) having at least one first port (190) which is aligned with a second port (188) of a second wall (172) of the second piece for passage of fastening means through said first and second ports, characterized in that at least one compressible seal (186) is interposed between said first and second walls, so that the first and second pieces are not in direct contact with each other in the mounting position, and in that the fastening means comprise at least one rivet (182) which is mounted in said first and second orifices and which is surrounded by a ring (184), said ring passing through said second orifice and being, in position d e assembly, held tight by the rivet against said first wall so that the seal is compressed between said first and second walls. 2. Body (156) according to claim 1, characterized in that the ring (184) comprises at one end an outer annular flange (196). 3. Body (156) according to claim 2, characterized in that the flange (196) is interposed between a head (194) of the rivet (182) and said second wall (172). 4. Body (156) according to claim 3, characterized in that the rivet comprises another head (192) jqpilèst, empositicmile mounting, bearing on said first wall (180). 5. Body (156) according to one of the preceding claims, characterized in that the seal (186) is plane. 6. Body (156) according to one of the preceding claims, characterized in that the seal (186) comprises an orifice (198) aligned with said first and second orifices (190, 188). 7. Body (156) according to one of the preceding claims, characterized in that the seal (186) is made of elastically deformable material, for example silicone. 8. Body according to one of the preceding claims, characterized in that the member is a discharge duct (156), the discharge duct comprising a tubular sleeve (158) for guiding an air flow and a grate finned member (164) mounted at an outlet end (162) of the sleeve, the sleeve being metallic and forming said first piece and the finned grid being of composite material and forming said second piece. 9. Turbomachine, characterized in that it comprises at least one member (156) according to one of the preceding claims. 10. A method of producing a turbomachine member (156) by fixing a first piece (158) of metal to a second piece (164) of composite material, the first piece comprising a first wall (180) comprising at least a first port (190) which is intended to be aligned with a second port (188) of a second wall (172) of the second piece, for the passage of fastening means (178) through said first and second ports, characterized in that it comprises the steps of: - interposing at least one seal (186) compressible between said first and second walls, so that the first and second parts are not in direct contact with each other; other in mounting position, - mounting at least one rivet (182) in said first and second orifices, a ring (184) being previously mounted around the rivet and being intended to pass through said second orifice, and - crimped r the rivet, so that the ring is held tight by the rivet against said first wall and that the seal is compressed between said first and second walls.