Fixed vane assembly for a turbine engine comprising variable-pitch blades

Abstract

The invention relates to a blade (7) for a static vane assembly (6), comprising: - a blade root (11) comprising a first blade-root portion (11a) intended to be connected to a hub (8) of the turbine engine (1) and a second blade-root portion (11b), the first and second blade-root portions (11a, 11b) being connected by a blade-root junction portion (11c) having a first external surface (17a) and an opposite second external surface (17b); - a first reinforcement (19a) and a second reinforcement (19b), the first reinforcement (19a) having a first internal surface (23a) configured to marry the first external surface (17a) and the second reinforcement (19b) having a second internal surface (23b) configured to marry the second external surface (17b); and - first attachment members (24a) configured to mechanically attach the first reinforcement (19a) to the first blade-root portion (11a) and second attachment members (24b) configured to mechanically attach the second reinforcement (19b) to the first blade-root portion (11a).

Description

[0001] DESCRIPTION

[0002] TITLE: Fixed turbomachine vane comprising variable-pitch blades

[0003] TECHNICAL FIELD

[0004] The present invention relates to the field of turbomachines. It relates in particular to a fixed vane of a turbomachine, for example a fixed vane comprising variable-pitch stator vanes, each fixed to a pivot. The invention applies in particular to an unducted turbomachine rectifier or to a ducted turbomachine rectifier.

[0005] STATE OF THE ART

[0006] Turbomachines comprising at least one unducted propeller are known as "open rotor" or "unducted fan". Such turbomachines may comprise two unducted and contra-rotating propellers (known by the acronym CROR for "Contra-Rotating Open Rotor") or a single unducted propeller and a stator comprising several stator blades (known by the acronym USF for "Unducted Single Fan"). The propellers may be placed at the rear of the gas generator (or engine) so as to be of the pusher type or at the front of the gas generator so as to be of the tractor type. These turbomachines are turboprops which are distinguished from turbojets by the use of a propeller outside the nacelle (unducted) instead of an internal fan. This makes it possible to increase the dilution ratio significantly without being penalized by the mass of the casings or nacelles intended to surround the propeller or fan blades.

[0007] The stator vanes of the rectifier are generally installed on a hub which carries the separation nozzle of the primary and secondary flows circulating respectively in a primary vein and around the inlet casing. Unlike the upstream propeller of a USF type turbomachine, the stator vanes of the rectifier are fixed in rotation relative to the axis of rotation of the upstream propeller and therefore do not undergo centrifugal force.

[0008] The stator blades extend from the inlet casing and can be variable-pitch if necessary. In this case, each stator blade root is pivotally mounted along a pitch axis and connected to a pitch-changing system mounted in the turbomachine. However, the integration area of ​​the stator blade root and pivot is a highly constrained area due to the presence of numerous pieces of equipment around them.

[0009] Current propeller blade fastening technologies, however, do not meet the need for fastening the stator blades of a turbomachine because they use the centrifugal force generated by the rotation of the propeller to press the blade root into its attachment. However, in a static blade, the absence of rotation, and therefore of centrifugal force, prevents the use of this fastening method. The blades of static blades are therefore generally fixed by bolting to a metal attachment comprising bolts extending either axially or radially, so as to fix the blade root to the attack. This type of attachment is, however, bulky tangentially, in particular when the bolts are mounted radially, which poses difficulties in integration into the turbomachine.

[0010] Furthermore, the attachment is subjected to significant bending forces and the areas of the blade root in which the bolts are introduced form stress concentration zones which undergo an asymmetrical force due to the pressure differences experienced by the intrados and extrados of the blade.

[0011] EXPOSED

[0012] An aim of the present application is to remedy the aforementioned drawbacks, by proposing a system for fixing the blades of a static blading of a turbomachine, the size of which is reduced while guaranteeing suitable support of the blades of the static blading.

[0013] For this purpose, according to a first aspect, a blade of a static blade of a turbomachine is proposed, comprising:

[0014] - a blade root comprising a first blade root portion intended to be connected to a hub of the turbomachine and a second blade root portion extending radially from the first blade root portion relative to a central axis of the turbomachine when the first blade root portion is connected to the hub of the turbomachine, the first and second blade root portions being connected to each other by a blade root joining portion, the blade root joining portion having a first external surface and a second external surface, opposite the first external surface;

[0015] - a first reinforcement and a second reinforcement, arranged on either side of the blade root junction portion, the first reinforcement having a first internal surface configured to match the first external surface of the blade root junction portion and the second reinforcement having a second internal surface configured to match the second external surface of the blade root junction portion; and

[0016] - first fastening members configured to mechanically fasten the first reinforcement to the first blade root portion and second fastening members configured to mechanically fasten the second reinforcement to the first blade root portion. Advantageously, the first external surface is concave, the second external surface is concave, the first internal surface of the first reinforcement is convex and the second internal surface of the second reinforcement is convex.

[0017] Advantageously, the blade comprises a platform comprising a radially external face configured to delimit an air flow vein passing through the blade and a radially internal face, the platform being fixedly mounted on the first reinforcement and / or on the second reinforcement.

[0018] Preferably, the blade comprises a first support arm comprising a first end fixed to the first reinforcement and a second opposite end, fixed to the platform, and / or a second support arm comprising a third end fixed to the second reinforcement and a fourth opposite end fixed to the platform.

[0019] Advantageously, the first reinforcement comprises a first reinforcement portion in contact with the first blade root portion, a second reinforcement portion in contact with the second blade root portion and a first reinforcement junction portion connecting the second reinforcement portion to the first reinforcement portion, the first convex internal surface being a surface of the first reinforcement junction portion and the first end of the first support arm being fixed to the first reinforcement portion.

[0020] Advantageously, the second reinforcement comprises a third reinforcement portion in contact with the first blade root portion, a fourth reinforcement portion in contact with the second blade root portion and a second reinforcement junction portion connecting the fourth reinforcement portion to the third reinforcement portion, the second convex internal surface being a surface of the second reinforcement junction portion and the third end of the second support arm being fixed to the third reinforcement portion.

[0021] Advantageously, each of the reinforcements comprises several first support arms distributed along an extrados surface of the blade and several second support arms distributed along an intrados surface of the blade.

[0022] In one embodiment, each of the reinforcements is metallic.

[0023] Advantageously, the platform comprises a first platform portion fixed to the first reinforcement and a second platform portion fixed to the second reinforcement. Advantageously, the second end of at least one of the first support arms and / or the fourth end of at least one of the second support arms is fixed to the platform by means of third fixing members.

[0024] Preferably, the blade comprises a first skin and a second skin, made of a composite material from a fiber preform and connected to each other at a leading edge of the blade and at a trailing edge of the blade, and a shaping part extending between the first skin and the second skin, inside the blade root junction portion.

[0025] The invention also relates to a blade of a turbomachine, comprising at least one blade as defined above, and a hub, the blade being fixedly mounted on the hub by means of the first fixing members and the second fixing members.

[0026] Advantageously, the blade assembly comprises an attachment suitable for being pivotally mounted relative to the hub around a setting axis, and in which the blade is fixedly mounted on the attachment by means of the first fixing members and the second fixing members.

[0027] DESCRIPTION OF FIGURES

[0028] Other characteristics, aims and advantages of the invention will emerge from the following description, which is purely illustrative and non-limiting, and which must be read in conjunction with the appended drawings in which:

[0029] Figure 1 illustrates a schematic view, in axial and partial section, of an example of a turbomachine which may comprise a blade of a static blading according to one embodiment;

[0030] Figure 2 is a schematic sectional view of an exemplary embodiment of a blade of a static blading according to one embodiment;

[0031] Figure 3 is a top view of an exemplary embodiment of a platform for a blade according to one embodiment of the invention; and

[0032] Figure 4 illustrates a schematic and partial view of an exemplary embodiment of the fixing of the main plate and the secondary plate of the platform of Figure 3.

[0033] Throughout the figures, similar elements have identical references.

[0034] DETAILED DESCRIPTION In Figure 1, the turbomachine 1 shown is an aircraft turbomachine. The turbomachine 1 comprises a fan or propeller 2, a compression section 3, a combustion chamber 4, a turbine section 5 downstream of the combustion chamber 4, and an exhaust casing 50. The turbomachine 1 further comprises a static blading 6.

[0035] In the example illustrated in Figure 1, the static blading 6 is a static blading arranged to straighten an air flow downstream of the propeller 2. However, the invention applies to any static (i.e. non-rotating) blading of a turbomachine 1, whether it is a straightening blading of a fan or a propeller, a straightening blading of a compression section, or a distributor blading of a turbine section. The static blading 6 comprises a hub 8 mounted fixedly relative to a casing 9 of the turbomachine 1, and at least one blade 7 extending from the hub 8. By way of example, the turbomachine 1 may in particular be a USF type turboprop comprising an unducted propeller 2, in which case the static blading 6 is unducted and extends downstream of the propeller 2 (see figure 1).In another example, the turbomachine 1 may be a turbojet comprising an unducted fan, in which case the static blade 6 may correspond to the unducted rectifier extending downstream of the fan which is known by the English designation “outlet guide vane”.

[0036] In the present description, the terms "upstream" and "downstream" are defined with respect to the direction of flow of the gases through the static blading 6. The axis of rotation of the rotor of the propeller 2 (respectively, of the fan) is called the X axis. In other words, the X axis is the central axis of the turbomachine 1. The axial direction corresponds to the direction of the X axis and a radial direction is a direction perpendicular to the X axis and passing through the X axis. Furthermore, the circumferential (or tangential) direction corresponds to a direction perpendicular to the X axis and not passing through it.

[0037] In the example illustrated in Figure 1, the static blading 6 comprises a plurality of blades 7 extending radially from the hub 8. Optionally, the blades 7 are variable-pitch, i.e. each blade 7 is pivotally mounted about a respective pitch axis Y, on a hub 8 of the static blading 6 (the pitch axis Y being fixed and substantially radial relative to the axis X). This is not, however, limiting, the blades 7 being able to be fixed relative to the hub 8, in particular when the fan is shrouded, the hub 8 then corresponding to the shell of the intermediate casing (which is located between the casing of the low-pressure compressor and the casing of the high-pressure compressor).

[0038] The static blading 6 thus comprises a hub 8 mounted fixedly relative to a casing 9 of the turbomachine 1. It is therefore non-rotating. The blades 7 of the blading 6 extend substantially radially relative to the axis X, for example along the setting axis Y.

[0039] In an embodiment in which the blades 7 are variable-pitch, the blade 6 comprises an actuating mechanism 10 for modifying the pitch angle of the blades 7 of the blade 6 in order to adapt the performance of the turbomachine 1 to the different flight phases. In addition, the blade 6 comprises a fastener 8a (or pivot) connecting a blade 7 to the hub 8. More precisely, each blade 7 comprises a blade root 11 which is mounted in the hub 8 via the fastener 8a. The fastener 8a is rotatably mounted relative to the hub 8 around the pitch axis Y of the blade 7. More precisely, the fastener 8a is rotatably mounted inside a housing provided in the hub 8, for example via rolling elements such as balls.

[0040] In the remainder of the description, for simplification, the invention will be described in the case of a variable-pitch blade 7 whose blade root 11 is mounted in the hub 8 by means of the attachment 8a. However, the present description is not limited to this configuration and applies mutatis mutandis to a fixed blade 7 whose root is mounted directly on the hub 8.

[0041] The blade 7 further comprises a blade root 11 intended to be connected to the hub 8, a blade 12 with an aerodynamic profile suitable for being placed in an air flow when the turbomachine 1 is in operation in order to generate lift.

[0042] The airfoil blade 12 has an upper surface 7a, a lower surface 7b, a leading edge 7c and a trailing edge 7d. The leading edge 7c is configured to extend opposite the flow of gases entering the turbomachine 1. The leading edge 7c corresponds to the front part of the airfoil which faces the airflow and which divides the airflow into an upper surface flow and an upper surface flow. The trailing edge 7d corresponds to the rear part of the airfoil, where the lower surface and upper surface flows meet.

[0043] The blade root 11 comprises a first lower blade root portion 11a intended to be connected to the hub 8 via the attachment 8a, and a second upper blade root portion 11b extending radially relative to the axis X from the first portion 11a when the first blade root portion 11a is connected to said hub 8 of the turbomachine 1. The second portion 11b is therefore connected to the aerodynamically profiled blade 12, possibly monolithically. The first portion 11a extends opposite the hub 8, while the second portion 11b extends radially relative to the hub 8, when the blade 7 is secured to the hub 8.

[0044] The blade root 11 further comprises a joining portion 11 c connecting the first and second portions 11 a, 11 b of the blade root 11 to each other.

[0045] In a first embodiment, the blade 7 is formed from a composite material. The blade 7 comprises a fiber reinforcement, and a matrix, for example a polymer matrix, the fiber reinforcement being embedded in a matrix. The fiber reinforcement may comprise woven or knitted three-dimensional fiber arrangements. The fiber reinforcement is further made such that it comprises warp yarns that extend continuously both within the airfoil portion 12 and within the blade root portion 11. Alternatively, the fiber reinforcement may comprise laminated two-dimensional fiber arrangements. The fibers of the fiber reinforcement comprise at least one of the following materials: carbon (typically silicon carbide), glass, aramid, polypropylene, and / or ceramic (typically an oxide ceramic). The matrix typically comprises an organic matrix (thermosetting, thermoplastic, or elastomer) or a carbon matrix.For example, the matrix comprises a plastic material, typically a polymer, for example epoxy, bismaleimide or polyimide.

[0046] The blade 7 may in particular comprise a first skin 13a and a second skin 13b, which are connected to each other and extend generally opposite each other. In particular, the skins 13a, 13b are connected at the blade tip over the entire chord of the blade 7, at the leading edge 7c and at the trailing edge 7d. The skins 13a, 13b may be monolithic and be made in a single piece from a fiber preform with varying thickness. Alternatively, the first skin 13a may be formed from a first portion of the fiber reinforcement in order to form the extrados 7a and the second skin 13b may be formed from a second portion of the fiber reinforcement in order to form the intrados 7b, the first and second portions of the fiber reinforcement then being connected, for example near the blade tip.

[0047] The first skin 13a and the second skin 13b may be separated by a cavity 14 which is open on a lower face of the blade root 11, so as to reduce the mass of the blade 7. The lower face of the blade root 11 corresponds to the face of the blade root 11 which is intended to be opposite the attachment 8a. The cavity 14 is not open at the blade head nor on the leading edge 7c nor on the trailing edge 7d of the blade 7.

[0048] The first skin 13a comprises a first lower end 15a opposite the head of the blade 7 and therefore the blade 12 with an aerodynamic profile. Similarly, the second skin 13b comprises a second lower end 15b opposite the head of the blade 7 and therefore the blade 12 with an aerodynamic profile. A decoupling is carried out in the fibrous reinforcement, at the level of the first end 15a and the second end 15b of the skins opposite the head of the blade, so that this first end 15a and this second end 15b are free. The first end 15a and the second end 15b then form the first portion 11a and are spaced apart from each other so as to extend tangentially against the attachment 8a, if necessary by means of a composite plywood 18 which will be described below.

[0049] Alternatively, the blade 7 is made of metal: in this case, the blade root 11 is shaped so that its end opposite the blade head comprises an extrados portion and an intrados portion which flare out from the second portion 11 b so as to extend substantially tangentially against the attachment to form two sections constituting the first portion 11 a of the blade root 11 .

[0050] The blade 7 may further comprise within it a shaping piece 16 extending between the first skin 13a and the second skin 13b (between the two sides in the case of the metal blade), inside the junction portion 11c of the blade root in the cavity 14. The shaping piece 16 thus makes it possible to reinforce the stiffness of the blade 7 at the bottom of the blade. The shaping piece 16 also makes it possible to ensure a progressive stiffness transition in the radial direction, in order to avoid stress concentrations at the exit of the clamping zone.

[0051] The shaping part 16 may in particular be formed from a composite material. The shaping part 16 comprises a fibrous reinforcement and a matrix, preferably a matrix compatible with the matrix of the fibrous reinforcement of the skins 13a, 13b (typically, the same matrix), the fibrous reinforcement being embedded in the matrix. The fibrous reinforcement of the shaping part 16 may in particular comprise fibers whose Young's modulus is greater than 15 GPa, for example carbon, aramid, glass or basalt fibers.

[0052] The blade 7 may further comprise one or more filling pieces 50, typically pieces made of foam or any other suitable material having a lower density than the composite material of the first skin 13a and the second skin 13b, placed between said first skin 13a and second skin 13b inside the blade 7, between the shaping piece 16 and the blade head (upper end of the blade 7), that is to say in a part of the cavity 14 extending within the blade 12 in order to stiffen the blade 7 and / or give the first skin 13a and the second skin 13b the final shape of the blade 12.

[0053] In one embodiment, and in particular when the blade 7 is made of composite material, the joining portion 11 c has a first concave external surface 17a arranged on the suction side 7a and a second concave external surface 17b opposite the first concave external surface 17a and arranged on the suction side 7b. Said first external surface 17a and second external surface 17b may be monolithic with each other, and may be curved in order to limit the risk of breakage between the first portion 11 a and the second portion 11 b during transmission of forces between the two. Possibly, the first external surface 17a may comprise two parts connected to each other by a common joining line, so that the first external surface 17a forms a non-flat angle having the joining line as its apex.In this case, the second external surface 17b may also comprise two parts connected to each other by a common joining line, so that the second external surface 17b forms a non-flat angle having the joining line as its apex. Possibly, for example, the two parts of the joining portion 11c may thus form a right angle. The attachment 8a comprises an upper radial surface 8b and is intended to receive the first portion 11a, and more precisely to receive a lower radial end 11e of the blade root 11. The first portion 11a is thus arranged against the upper radial surface 8b of the attachment 8. Alternatively, and as illustrated in the example of FIG. 2, a composite plywood 18 may be arranged between the first portion 11a and the upper radial surface 8b to close the blade root 11 so as to absorb the forces and improve the rigidity of the blade 7.

[0054] The blade 7 further comprises a first reinforcement 19a and a second reinforcement 19b arranged on either side of the blade root 11 and more precisely of the joining portion 11c. In particular, the first reinforcement 19a is arranged on the extrados side 7a and the second reinforcement 19b is arranged on the intrados side 7b of the blade 7.

[0055] The first reinforcement 19a comprises a first reinforcement portion 20a, a second reinforcement portion 22a, and a first reinforcement joining portion 21a connecting the first reinforcement portion 20a and the second reinforcement portion 22a. The first reinforcement portion 20a is in contact with the first blade root portion 11a, the second reinforcement portion 22a is in contact with the second blade root portion 11b, and the first reinforcement joining portion 21a is in contact with the joining portion 11c of the blade root.

[0056] More specifically, the first reinforcement 19a comprises a first convex internal surface 23a configured to match the first concave external surface 17a of the joining portion 11c of the blade root 11. More particularly, the first convex internal surface 23a is a surface of the first reinforcing joining portion 21a, such that the first reinforcement 19a matches the extrados face 7a of the blade root 11, thus making it possible to stiffen the blade 7 and to absorb as much as possible the forces along the length of the first reinforcement 19a. Possibly, the first internal surface 23a may comprise two parts connected to each other by a common joining line, such that the first internal surface 23a forms a non-flat angle having the joining line as its apex.

[0057] Similarly, the second reinforcement 19b comprises a third reinforcement portion 20b, a fourth reinforcement portion 22b, and a second reinforcement joining portion 21b connecting the third reinforcement portion 20b and the fourth reinforcement portion 22b. The third reinforcement portion 20b is in contact with the first blade root portion 11a, the fourth reinforcement portion 22b is in contact with the second blade root portion 11b, and the second reinforcement joining portion 21b is in contact with the joining portion 11c of the blade root.

[0058] More specifically, the second reinforcement 19b comprises a second convex internal surface 23b configured to match the second concave external surface 17b of the joining portion 11c of the blade root 11. More particularly, the second convex internal surface 23b is a surface of the third joining portion of the reinforcement 21b, such that the second reinforcement 19b generally matches the intrados face 7b of the blade root 11, thus making it possible to stiffen the blade 7 and to absorb as much as possible the forces along the length of the second reinforcement 19b. Possibly, the second internal surface 23b may comprise two parts connected to each other by a common joining line, such that the second internal surface 23b forms a non-flat angle having the joining line as its apex.

[0059] Thus, the first reinforcement 19a and the second reinforcement 19b make it possible to stiffen the junction portion which is an area at high risk of breakage when using the turbomachine 1.

[0060] The blade 7 further comprises first fastening members 24a configured to mechanically fasten the first reinforcement 19a to the first portion 11a of the blade root. More specifically, the first fastening members 24a can fasten the first reinforcement 19a to the first portion 11a and to the composite plywood 18 if applicable.

[0061] Furthermore, in order to limit the number of parts, the first fixing members 24a can also be configured to fix the blade 7 (and more particularly a part of the first skin 13a forming a part of the first blade root portion 11a) to the attachment 8a and therefore to the hub 8.

[0062] The blade 7 is further connected to the hub 8, for example by means of the first fixing members 24a.

[0063] For example, the first fasteners 24a comprise one or more bolts whose screws pass through the first portion 11a (more particularly the first skin 13a), the composite plywood 18 and the fastener 8a.

[0064] Thus, the first fixing members 24a make it possible on the one hand to fix the first reinforcement 19a on the blade 7 (on the first portion 11a), and on the other hand to connect the blade 7 (the first portion 11a and the composite plywood 18 if applicable) to the hub 8.

[0065] Also and more specifically, the first fixing members 24a fix the first reinforcement portion 20a to the first blade root portion 11a. In addition and as described previously, the first fixing members 24a fix the first blade root portion 11a to the hub 8 via the fastener 8a. Thus, the first fixing members 24a are located at a distance from the blade root junction portion 11c and the first reinforcement junction portion 21a, which are parts at high risk of breakage.

[0066] Similarly, the blade 7 further comprises second fastening members 24b configured to mechanically fasten the second reinforcement 19b to the first portion 11a of the blade root. More specifically, the second fastening members 24b can fasten the second reinforcement 19b to the first portion 11a and to the composite plywood 18 if applicable.

[0067] Furthermore, in order to limit the number of parts, the second fixing members 24b can also be configured to fix the blade 7 (and more particularly a part of the second skin 13b forming a part of the first blade root portion 11a) to the attachment 8a and therefore to the hub 8. The blade 7 is further connected to the hub 8, for example by means of the second fixing members 24b.

[0068] For example, the second fixing members 24b comprise one or more bolts whose screws pass through the first portion 11a (more particularly the second skin 13b), the composite plywood 18 and the fastener 8a.

[0069] Thus, the second fixing members 24b make it possible on the one hand to fix the second reinforcement 19b on the blade 7 (on the first portion 11a), and on the other hand to connect the blade 7 (the first portion 11a and the composite plywood 18 if applicable) to the hub 8.

[0070] Also and more specifically, the second fixing members 24b fix the third reinforcement portion 20b to the first blade root portion 11a. Furthermore and as described previously, the second fixing members 24b fix the first blade root portion 11a to the hub 8 via the fastener 8a. Thus, the second fixing members 24b are located at a distance from the blade root junction portion 11c and the second reinforcement junction portion 21b, which are parts at high risk of breakage.

[0071] On the one hand, the blade 7 is thus fixedly mounted on the hub 8 by means of the first fixing members 24a and the second fixing members 24b.

[0072] On the other hand, the first reinforcement 19a and the second reinforcement 19b thus make it possible to stiffen the area where the blade 7 is attached to the hub 8, which is an area with a high risk of breakage when using the turbomachine 1, because this is the place where the forces are concentrated to be transmitted between the blade 7 and the hub 8.

[0073] The first reinforcement 19a and the second reinforcement 19b may form a single monolithic piece surrounding the blade root 11 or alternatively be two separate pieces.

[0074] In all cases, the contacts and fixings of the first reinforcement 19a and the second reinforcement 19b with the blade root 11, and in particular with the blade root junction portion 11c (respectively with the first external concave surface 17a and with the second external concave surface 17b) make it possible to press the first skin 13a and the second skin 13b against the shaping part 16 to limit the out-of-plane stresses in the concave zones of the blade root 11, which are very dangerous for the integrity of the interfaces between the skins 13a, 13b and the shaping part 16. The first reinforcement 19a and the second reinforcement 19b thus make it possible to reduce the stresses locally by better distributing the transmitted forces. This reduction in stresses is even greater when the first external surface 17a and the second external surface 17b are curved.

[0075] Advantageously, the first reinforcement 19a and the second reinforcement 19b are metallic, in particular titanium.

[0076] In addition, the blade 7 comprises an aerodynamic platform 25, an example of which is illustrated in FIG. 2 (sectional view), in FIG. 3 (top view) and in FIG. 4. In one embodiment, the platform 25 further comprises a first platform portion 25a and a second platform portion 25b. The first platform portion 25a comprises a main plate 28a configured to bear against a first face of the blade 7, for example against the extrados face 7a of the blade 7, in particular against the second portion 11b of the blade root on the extrados side 7a. The second platform portion 25b comprises a secondary plate 28b extending in the extension of the main plate 28a.The secondary plate 28b is furthermore fixed to the main plate 28a and configured to bear against a second face of the blade 7, for example against the intrados face 7b of the blade 7, in particular against the second portion 11b of the blade root on the intrados side 7b.

[0077] The platform 25 comprises a radially external face 26 (relative to the axis X) configured to delimit an air flow vein passing through the blading 6, and a radially internal face 27. The platform 25 thus makes it possible to delimit a radially lower part of the air vein passing through the blading 6.

[0078] The platform 25 may in particular be made of plastic or metal, for example polyetheretherketone (PEEK), polyetherimide (PEI), aluminum-based alloy or even composite material.

[0079] Preferably, the first platform part 25a is mounted cantilevered on the second platform part 25b, as illustrated for example in FIG. 4. The first platform part 25a is preferably mechanically fixed on the second platform part 25b, which allows disassembly under the wing of the platform 25 and interchangeability of the blade 7 while minimizing the mass and geometric accidents on the path of the air flow (i.e. rising or falling steps, depending on the direction of the aerodynamic flow). It is in fact sufficient to disassemble the first platform part 25a or the second platform part 25b to access the attachment 8a, the blade root 11 and the hub 8.

[0080] The first platform part 25a may in particular be riveted to the second platform part 25b by means of rivets 47. For this purpose, the first platform part 25a comprises first connecting edges 29a and the second platform part 25b comprises second connecting edges 29b. The first connecting edges 29a and the second connecting edges 29b are assembled by riveting and may be thinned so that the thickness of the platform 25 is substantially constant (as illustrated for example in FIG. 4). In other words, the sum of the thickness of the first and second connecting edges 29a and 29b at the assembly is substantially equal to the thickness of the main plate 28a and the secondary plate 28b at a distance from the assembly.When the platform 25 is made of one of the materials listed above, the thickness of the platform 25 may be between 5 mm and 15 mm, preferably between 10 mm and 15 mm. Furthermore, when the main 28a and secondary 28b plates are riveted, said main and secondary plates 28a and 28b overlap over a strip whose width is at least equal to 1.5 times the diameter of the rivets 47. Rivets 47 having a diameter of 6 mm may for example be used.

[0081] In addition, in order to avoid air recirculation at the base of the blade 11, the blade 7 further comprises a seal 48 mounted between the main plate 28a and the secondary plate 28b, between the main plate 28a and the extrados 7a of the blade 7 and between the secondary plate 28b and the intrados 7b of the blade 7. The seal 48 can be co-injected with the platform 25 or added and bonded after manufacture of the platform 25. The seal 48 can for example be made of rubber, typically ethylene-propylene-diene monomer (EPDM), silicone or any suitable material.

[0082] The main plate 28a and the secondary plate 28b extend in a generally circumferential direction relative to the X axis, i.e. in a plane normal to the Y pivot axis, in order to radially delimit the flow vein inside.

[0083] Alternatively, the platform 25 may be monolithic and enclose the blade root 11.

[0084] Furthermore, the platform 25 is fixedly mounted on the first reinforcement 19a and / or on the second reinforcement 19b, which make it possible to support the platform 25. More precisely, the blade 7, and more particularly the first reinforcement 19a, comprises a first support arm 30a and / or the blade 7, and more particularly the second reinforcement 19b, comprises a second support arm 30b. The first support arm 30a and the second support arm 30b are arranged on either side of the blade root 11. For example, the first support arm 30a is arranged on the extrados side 7a of the blade root 11, while the second support arm 30b is arranged on the intrados side 7b of the blade root 11. The first support arm 30a comprises a first lower end 31a fixed to the first reinforcement 19a and a second opposite upper end 32a fixed to the platform 25.Similarly, the second support arm 30b comprises a third lower end 31b fixed to the second reinforcement 19b and a fourth opposite upper end 32b fixed to the platform 25.

[0085] More specifically, the first lower end 31a of the first support arm 30a is fixed to the first reinforcement portion 20a. Thus, the fixing of the first support arm 30a on the first reinforcement 19a is carried out at a distance from the first reinforcement junction portion 21a, in order to protect this area. In addition, the second upper end 32a of the first support arm 30a is fixed to the platform 25, more particularly to the first platform part 25a, on the internal face 27, at a point located at a shorter distance from the Y axis than the first lower end 31a. In this way, the support of the platform 25 is stiffened and can transmit significant forces, for example due to the action of the air circulating in contact with the platform 25.

[0086] The second upper end 32a of the first support arm is fixed to the platform for example by means of third fixing members 33a.

[0087] In one embodiment, the third fixing members 33a comprise a screw cooperating with a counterbore made in the platform 25, more precisely in the first platform part 25a, and with a thread made in said second upper end 32a of the first support arm 30a, this thread being open on this second upper end 32a of the first support arm 30a. The counterbore is accessible from the upper face 26 of the platform 25, so as to be able to insert the screw once the different parts of the platform 25 are positioned, or on the contrary to be able to remove them. To gain aerodynamics, a plug can be inserted into the counterbore after inserting the third fixing members 33a.

[0088] In another embodiment not illustrated, the third fixing members 33a comprise a ring whose interior is at least partially tapped. Preferably, the interior of the ring comprises a first tapping at one end and a second tapping of opposite or identical direction at an opposite end, the ring being fixed on the one hand to the platform 25 (for example to a protrusion formed on the internal face 27) by the first tapping and on the other hand to the second upper end 32a by the second tapping. In other words, the ring surrounds the protrusion and the second upper end 32a to secure the first support arm 30a to the platform.

[0089] In any case, the third fixing members 33a are configured to allow easy mounting and dismounting of said fixing.

[0090] Similarly, the third lower end 31 b of the second support arm 30 b is fixed to the third reinforcement portion 20 b. Thus, the fixing of the second support arm 30 b to the second reinforcement 19 b is carried out at a distance from the second reinforcement junction portion 21 b, in order to protect this area. In addition, the fourth upper end 32 b of the second support arm 30 b is fixed to the platform 25, more particularly to the second platform portion 25 b, on the internal face 27, at a point located at a shorter distance from the Y axis than the third lower end 31 b of the second support arm 30 b. In this way, the support of the platform 25 is stiffened and can better transmit greater forces, for example due to the action of the air circulating in contact with the platform 25.

[0091] The fourth upper end 32b of the second support arm 30b is fixed to the platform 25 for example by means of fourth fixing members 33b

[0092] In one embodiment, the fourth fixing members comprise a screw cooperating with a counterbore made in the platform 25, more precisely in the second platform part 25b, and with a thread made in said fourth upper end 32b of the second support arm 30b, this thread being open on this fourth upper end 32b of the second support arm 30b. To gain in aerodynamics, a plug can be inserted in the counterbore after inserting the third fixing members 33a.

[0093] In another embodiment not illustrated, the fourth fixing members 33 comprise a ring whose interior is at least partially tapped. Preferably, the interior of the ring comprises a first tapping at one end and a second tapping of opposite or identical direction at an opposite end, the ring being fixed on the one hand to the platform 25 (for example to a protrusion formed on the internal face 27) by the first tapping and on the other hand to the fourth upper end 32b by the second tapping. In other words, the ring surrounds the protrusion and the fourth upper end 32b to secure the second support arm 30b to the platform 25.

[0094] In any case, the fourth fixing members are configured to allow easy assembly and disassembly of said fixing.

[0095] In order to gain rigidity, the first support arm 30a may comprise a first rod 34a extending between the first support arm and the second reinforcement portion 21a, so as to always protect the reinforcement junction portion 21a while improving the force absorption of the first reinforcement 19a. Similarly, the second support arm 30b may comprise a second rod 34b extending between the second support arm 30b and the fourth reinforcement portion 22b, so as to always protect the reinforcement junction portion 21a while improving the force absorption of the second reinforcement 19b.

[0096] In one embodiment, the blade 7 may comprise several first support arms 30a and / or several second support arms 30b. For example, the blade 7 may comprise at least two first support arms 30a and two second support arms 30b. Taking into account the usual dimensions (in particular of the chord) of the stator blades 7 and therefore of the first reinforcement 19a and of the second reinforcement 19b, the blade 7 may comprise at most four first and four second support arms 30a and 30b. For example, the blade comprises three first reinforcement arms 30a and three second reinforcement arms 30b. The first reinforcement arms 30a and the second reinforcement arms 30b are then substantially identical to each other, that is to say that the first support arms 30a are identical to each other and the second support arms 30b are identical to each other.In all embodiments with several first support arms 30a and / or second support arms 30b, the first support arms 30a and the second support arms 30b are arranged so as to extend respectively along the first reinforcement 19a and the second reinforcement 19b, and therefore substantially along the blade 7 between the leading edge 7c and the trailing edge 7d, i.e. along the chord of the blade 7. The first support arms 30a may for example be arranged on the suction side 7a of the blade root 11 and the second support arms 30b on the pressure side 7b of the blade root 11. In other words, the first support arms 30a, respectively the second support arms 30b, are substantially aligned along the blade root 11a between the leading edge 7c and the trailing edge 7d.Preferably, two first support arms 30a or two second support arms 30b successively along the blade root 11 are then spaced apart by a constant distance, in order to uniformly distribute the absorption of forces along the first reinforcement 19a and second reinforcement 19b.

[0097] The platform 25 can thus be attached and fixed to the first and / or second support arms 30a and 30b. Alternatively, the platform 25 can be monolithic with at least one of the first or second support arms 30a and 30b, and be attached and fixed to the other first and second support arms 30a and 30b. Finally, the platform 25 can be monolithic with all of the first and second support arms 30a and 30b.

[0098] Finally, each of the first support arms 30a may comprise a first rod 34a as defined previously. Similarly, each of the second support arms 30b may comprise a second rod 34b as defined previously.

[0099] The proposed blading 6 thus makes it possible to reduce the tangential and radial size at the blade root 11, while preserving the integrity of the blade root 11 by ensuring the absorption of forces between the blade 7 and the hub 8 and ensuring the support of the aerodynamic platform 25.

Claims

CLAIMS 1. Blade (7) of a static blade (6) of a turbomachine (1), comprising: - a blade root (11) comprising a first blade root portion (11a) intended to be connected to a hub (8) of the turbomachine (1) and a second blade root portion (11b) extending radially from the first blade root portion (11a) relative to a central axis (X) of the turbomachine (1) when the first blade root portion (11a) is connected to the hub (8) of the turbomachine (1), the first and second blade root portions (11a, 11b) being connected to each other by a blade root joining portion (11c), the blade root joining portion (11c) having a first external surface (17a) and a second external surface (17b), opposite the first external surface (17a); - a first reinforcement (19a) and a second reinforcement (19b), arranged on either side of the blade root joining portion (11c), the first reinforcement (19a) having a first internal surface (23a) configured to match the first external surface (17a) of the blade root joining portion (11c) and the second reinforcement (19b) having a second internal surface (23b) configured to match the second external surface (17b) of the blade root joining portion (11c); and - first fixing members (24a) configured to mechanically fix the first reinforcement (19a) to the first blade root portion (11a) and second fixing members (24b) configured to mechanically fix the second reinforcement (19b) to the first blade root portion (11a).

2. Blade according to claim 1, in which the first external surface (17a) is concave, the second external surface (17b) is concave, the first internal surface (23a) of the first reinforcement is convex and the second internal surface (23b) of the second reinforcement is convex.

3. Blade (7) according to claim 2, comprising a platform (25) having a radially external face (26) configured to delimit an air flow vein passing through the blading and a radially internal face (27), the platform (25) being fixedly mounted on the first reinforcement (19a) and / or on the second reinforcement (19b).

4. Blade (7) according to claim 3, comprising a first support arm (30a) having a first end (31a) fixed to the first reinforcement (19a) and a second opposite end (32a), fixed to the platform (25), and / or a second support arm (30b) having a third end (31 b) fixed to the second reinforcement (19b) and a fourth opposite end (32b) fixed to the platform (25).

5. Blade (7) according to claim 4, wherein the first reinforcement (19a) comprises a first reinforcement portion (20a) in contact with the first blade root portion (11a), a second reinforcement portion (22a) in contact with the second blade root portion (11b) and a first reinforcement junction portion (21a) connecting the second reinforcement portion (22a) to the first reinforcement portion (20a), the first convex internal surface (23a) being a surface of the first reinforcement junction portion (21a) and the first end (31a) of the first support arm being fixed to the first reinforcement portion (20a).

6. Blade (7) according to one of claims 4 or 5, wherein the second reinforcement (19b) comprises a third reinforcement portion (20b) in contact with the first blade root portion (11a), a fourth reinforcement portion (22b) in contact with the second blade root portion (11b) and a second reinforcement junction portion (21b) connecting the fourth reinforcement portion (22b) to the third reinforcement portion (20b), the second convex internal surface (23b) being a surface of the second reinforcement junction portion (21b) and the third end (31b) of the second support arm being fixed to the third reinforcement portion (20b).

7. Blade according to one of claims 4 to 6, in which each of the reinforcements (19a; 19b) comprises several first support arms (30a) distributed along an extrados surface (7a) of the blade (7) and several second support arms (30b) distributed along an intrados surface (7b) of the blade (7).

8. Blade (7) according to any one of claims 3 to 7, in which the platform (25) comprises a first platform part (25a) fixed to the first reinforcement (19a) and a second platform part (25b) fixed to the second reinforcement (19b).

9. Blade (7) according to one of claims 4 to 8, in which the second end (32a) of at least one of the first support arms (30a) and / or the fourth end (32b) of at least one of the second support arms (30b) is fixed to the platform (25) by means of third fixing members (33a; 33b).

10. Blade (7) according to one of claims 1 to 9, in which each of the reinforcements (19a; 19b) is metallic.

11. Blade (7) according to any one of claims 1 to 10, comprising a first skin (13a) and a second skin (13b), made of a composite material from a fiber preform and connected to each other at a leading edge (7c) of the blade (7) and at a trailing edge (7d) of the blade (7), and a shaping part (16) extending between the first skin (13a) and the second skin (13b), inside the blade root junction portion (11c).

12. Blading (6) of a turbomachine (1), comprising at least one blade (7) according to any one of claims 1 to 11, and a hub (8), the blade (7) being fixedly mounted on the hub (8) by means of the first fixing members (24a) and the second fixing members (24b).

13. Blading (6) according to claim 12, comprising an attachment (8a) suitable for being pivotally mounted relative to the hub (8) around a setting axis (Y), and in which the blade (7) is fixedly mounted on the attachment (8a) by means of the first fixing members (24a) and the second fixing members (24b).

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