BLADE SECTOR FOR A MOBILE WHEEL OF AN AIRCRAFT TURBOMACHINE MODULE, COMPRISING AN IMPROVED DYNAMIC DAMPING DEVICE

Abstract

The invention relates to a bladed sector (20) for a mobile wheel of an aircraft turbomachine module, the sector comprising an internal blade cavity (42) delimited by a first external blade wall (21) and by a second external blade wall (19), the sector being equipped with a dynamic damping device (50) comprising a first friction member (52) housed in the cavity (42) and extending radially from a fixed internal radial end (54), to a free external radial end (56) of friction against an internal friction surface (58) of the first blade wall (21), the member (52) having a domed shape in the direction of the first wall (21) so as to delimit a hollow (66) open in the direction of the second wall (19), the first friction member (52) having a center of gravity (74) located inside the hollow (66) of this first member. Figure for abstract: Figure 4

Description

Title of the invention: BLADE SECTOR FOR A MOVING WHEEL OF AN AIRCRAFT TURBOMACHINE MODULE, COMPRISING AN IMPROVED DYNAMIC DAMPING DEVICE Technical field

[0001] The present invention relates to the field of aircraft turbomachines, and more precisely to the design of the bladed sectors present within the moving wheels, forming the different modules of the turbomachines, namely the turbines and the compressors.

[0002] It relates more specifically to the dynamic damping by friction of the vibrations likely to occur on the bladed sectors, these sectors in the form of single-bladed vanes or multi-bladed sectors succeeding one another in the circumferential direction to form an annular row of blades.

[0003] The invention applies to all turbomachine designs, for example turbojets with a fan driven directly by a low-pressure body, or driven indirectly by a reducer. STATE OF PRIOR ART

[0004] The compressors and turbines of aircraft turbomachines are produced by an axial succession of fixed and mobile bladed wheels, also called stator bladed wheels, and rotor bladed wheels. In the case where such a bladed wheel is angularly sectored, namely in the circumferential direction of the wheel, it is usually appropriate to limit the vibrational stresses on the bladed sectors arranged adjacently in the circumferential direction of the wheel.

[0005] To do this, means are implemented to ensure dynamic damping of these sectors, by dissipating the energy of the resonance by friction between the heels of these sectors. Such a damping solution is for example known from document FR 3 085 712 AL

[0006] Another more conventional solution consists of implementing a contact friction technology, between the heels of adjacent sectors having particular shapes. This technology, also called "pretorsion", is characterized by a specific cut of the two opposite circumferential faces of the heel, with a protrusion on the extrados side, and an imprint of complementary shape on the intrados side. The two-by-two cooperation of these circumferential faces allows the two adjacent heels to be held in place relative to each other, in the axial direction. This Pretorsion technology is also referred to by the English term "interlock".

[0007] When assembling the blades, a support of the circumferential contact faces is generated by means of an angular deformation of the blade, constituting the desired pretorsion.

[0008] In operation, the vibrations of the blades induce relative sliding at the circumferential faces of the heels, which, coupled with the contact pressures, create friction damping.

[0009] With this technology, the contact force between the lugs can vary during operation of the turbomachine. This variation can come from the natural rotation of the blade around its twist axis (clockwise or counterclockwise), or from the relative movement of the adjacent lugs in the circumferential direction (approaching or separating). When mounting the sectors, it is necessary to take into account these possible variations in operation, and to ensure that at high speed, i.e. at the speed where dynamic damping is mainly sought, the target contact force is achieved. This can lead to applying a very high contact force during assembly of the sectors, which results in significant static overstresses, likely to weaken these bladed sectors and / or reduce their service life.This disadvantage is more or less restrictive, depending on the material used and its ability to withstand such stresses. For example, for sectors made of ceramic matrix composite material, also known as CMC material, the permissible mechanical stresses often remain low, which makes the sectors not very tolerant to this pretorsion principle. Thus, when a bladed sector is made of CMC material, it may prove incompatible with the need to apply strong pretorsion during assembly, required for satisfactory damping at the desired speed. However, CMC materials are advantageous because they withstand high temperatures ranging, for example, from 600°C to 1400°C, offering better resistance to these high temperatures. As a result, CMC materials require less cooling.Since this cooling traditionally comes from a sample in the compressor which impacts the efficiency of the turbomachine, CMC materials therefore make it possible to improve engine efficiency, which reduces fuel consumption. It is also noted that CMC materials can be used on parts that are not cooled, in order to be able to increase the temperature of the flow that the blades undergo, and thus improve efficiency.

[0010] Furthermore, the use of CMC materials contributes to optimizing the performance of turbomachines, in particular by reducing the overall mass of the turbomachine which further contributes to a reduction in fuel consumption, and therefore to a significant reduction in polluting emissions.

[0011] It is noted that other dynamic damping solutions are known, such as adding friction elements to the interface between the beads, at the level of their circumferential faces which cooperate two by two. However, these solutions generally have the disadvantage of generating aerodynamic disturbances at the level of the vein. Statement of the invention

[0012] To address the drawbacks mentioned above, the invention firstly relates to a bladed sector for a mobile wheel of an aircraft turbomachine module, the sector comprising a root and at least one hollow blade arranged outwardly relative to the root in a radial direction of this sector, the blade comprising an internal cavity delimited by a first external blade wall externally forming a first aerodynamic surface corresponding to one of a lower surface and an upper surface of the blade, as well as a second external blade wall externally forming a second aerodynamic surface corresponding to the other of the lower surface and the upper surface of the blade, the sector being equipped with a dynamic damping device comprising a first friction member housed in the internal blade cavity.

[0013] According to the invention, the first friction member extends radially inside the internal blade cavity, from a fixed internal radial end, to an external radial end free of friction against an internal friction surface of the first external blade wall, the first friction member having a domed shape in the direction of the first external blade wall, so as to delimit a hollow open in the direction of the second external blade wall all along the first friction member in the radial direction, the first friction member having a center of gravity located inside said hollow of this first member.

[0014] The invention thus makes it possible to obtain the dynamic damping function by friction, in a simple, reliable, efficient and low-mass manner. Indeed, the principle according to the invention is based on the implementation of a friction member of domed shape and extending radially, with its center of gravity located inside the hollow defined by this domed shape. In operation, when the friction member is subjected to the centrifugal effect, the shift of the center of gravity inside the hollow, in the direction of the internal friction surface of the first external blade wall, has the consequence of generating on this member a centrifugal force with not only a radial component, but also a circumferential / tangential component forcing the external radial end free of friction against the internal friction surface of the first external blade wall.The resulting circumferential / tangential support between these two elements, combined with the different displacements. potentials likely to be observed between these two elements of different stiffnesses due to their distinct shapes and dimensions, contributes to the dissipation of energy advantageously reducing the vibration level.

[0015] Also, the principle makes it possible to overcome the constraints associated with the principle of pre-torsion of the blades encountered in the prior art. In particular, it is no longer necessary to introduce high static pre-torsion constraints in the bladed sectors during their assembly, and the machining of complementary complex shapes on the opposite circumferential faces of the heels is no longer required. Advantageously, the invention allows the use of various materials for the production of the bladed sectors, including CMC materials.

[0016] The domed shape of the friction member not only allows the principle of circumferential support of the free external radial end of the member against the internal surface of the first external blade wall to be obtained, but it also advantageously provides contact which greatly limits the risks of damage and injury. Indeed, the local contact observed between the two elements is preferentially surface, resulting from the crushing of a linear contact.

[0017] The invention also has the advantage of not requiring the use of friction elements attached circumferentially between the beads, and therefore of avoiding the presence of complex additional parts between the beads, which advantageously leads to a reduction in the overall mass of the bladed wheel. Manufacturing is also simplified due to the absence of these friction elements of complex shape attached circumferentially between the beads.

[0018] The invention furthermore preferably provides at least any one of the following optional characteristics, taken individually or in combination.

[0019] Preferably, the first friction member has a convex surface facing the internal friction surface of the first external blade wall, as well as an opposite concave surface delimiting the hollow.

[0020] Preferably, the first friction member has a cross-section of general shape:

[0021] - C or U; or

[0022] - arc of a circle, preferably a semicircle; or

[0023] - portion of an ellipse, preferably a half-ellipse; or

[0024] - evolving radius curve.

[0025] Other curved shapes can nevertheless be envisaged, without departing from the scope of the invention.

[0026] Preferably, the fixed internal radial end of the first friction member is spaced from the internal friction surface of the first external blade wall, and in a nominal unstressed configuration of the bladed sector, the end free external radial of the first friction member is in abutment against the internal friction surface of the first external blade wall, or close to this internal surface. In the latter case, the aforementioned centrifugal force has the consequence of elastically deforming the friction member before it bears on the blade wall, then of accentuating the intensity of this circumferential support.

[0027] Preferably, the first friction member extends over a radial height greater than or equal to 60% of the total radial height HT of the blade.

[0028] Preferably, the first friction member comprises an excess thickness at the level of its portion located furthest from an opening of the hollow formed by this first member. This makes it possible to further shift the center of gravity of the friction member towards the blade wall, and thus to intensify the dynamic damping of the vibrations.

[0029] Preferably, the sector is equipped with a second friction member extending radially inside the internal blade cavity, from a fixed internal radial end, to an external radial end free of friction against an internal friction surface of the second external blade wall, the second friction member having a domed shape in the direction of the second external blade wall, so as to delimit a hollow open in the direction of the first external blade wall along the entire length of the second friction member in the radial direction, the second friction member having a center of gravity located inside said hollow of this second member. It is noted that all of the optional characteristics, described for the first friction member, apply in an identical or similar manner to the second friction member.

[0030] It is noted that the bladed sector according to the invention forms a vane, that is to say a single-bladed sector of small circumferential extent, or a sector comprising several blades secured to the root, and forming in the latter case a more substantial angular sector of the moving wheel into which it is integrated.

[0031] Preferably, the bladed sector comprises a support carrying the first friction member, the support being housed and fixed in a receiving cavity of the support, opening onto a radially internal end face of the root. This design makes it easier to manufacture the bladed sector, since the support and its friction member can be produced in the form of an assembly which is then introduced into the receiving cavity of the support, radially outwards, from the radially internal end face of the root.

[0032] Preferably, all or part of the bladed sector is made of CMC material, in particular the walls of the blade, and each friction member.

[0033] Finally, the invention relates to an aircraft turbomachine comprising at least one such bladed sector, integrated into one or more moving wheels of the compressor and / or the turbine of this turbomachine. Preferably, it is a low-pressure turbine wheel. It is further noted that the turbomachine is preferably a double-flow, double-spool turbojet, even if other types of turbomachines can be envisaged, without departing from the scope of the invention.

[0034] Other advantages and characteristics of the invention will appear in the detailed non-limiting description below. Brief description of the drawings

[0035] This description will be made with regard to the attached drawings among which:

[0036] [Fig-1] is a longitudinal sectional view of a turbojet engine;

[0037] [Fig.2] is a perspective view of a turbine blade equipping the turbojet engine shown in the preceding figure;

[0038] [Fig.2A] is a partial longitudinal sectional view of a turbine wheel equipped with blades like that of the previous figure;

[0039] [Fig.3] is a sectional view of a blade according to a first preferred embodiment of the invention, in a nominal unstressed configuration;

[0040] [Fig.4] is a cross-sectional view of the blade, taken along line IV-IV of [Fig.3];

[0041] [Fig.5] is a partial sectional view similar to that of [Fig.3], with the blade shown in a stressed configuration, as observed in operation;

[0042] [Fig.6] is a cross-sectional view of the blade, taken along line VI-VI of [Fig.5];

[0043] [Fig.7] is a cross-sectional view similar to the previous one, with the blade being in the form of a second preferred embodiment of the invention;

[0044] [Fig.8] is a partial cross-sectional view similar to the previous one, with the blade being in the form of a third preferred embodiment of the invention;

[0045] [Fig.9] is a partial sectional view of a blade in the form of a fourth preferred embodiment of the invention;

[0046] [Fig. 10] is a partial perspective view of a portion of the blade shown in the preceding figure. DETAILED DESCRIPTION OF THE INVENTION

[0047] Referring firstly to [Fig.l], there is shown an aircraft turbomachine 1, according to a preferred embodiment of the invention. This is a double-flow, double-spool turbojet. However, it could be a turbomachine of another type, for example a turboprop, without departing from the scope of the invention.

[0048] The turbomachine 1 has an axis X around which its various components extend, this axis being called the longitudinal axis of the turbomachine. It comprises, from upstream to downstream along a main direction 5 of gas flow through this turbomachine, a fan 3, a low pressure compressor 4, a high pressure compressor 6, a combustion chamber 11, a high pressure turbine 7 and a low pressure turbine 8.

[0049] Conventionally, after passing through the fan, the air divides into a central primary flow 12a and a secondary flow 12b which surrounds the primary flow. The primary flow 12a flows in a main gas circulation vein 14a passing through the compressors 4, 6, the combustion chamber 11 and the turbines 7, 8. The secondary flow 12b flows in a secondary vein 14b delimited radially outwards by a motor casing, surrounded by a nacelle 9.

[0050] [Fig. 2] represents a moving blade 20, intended to equip any one of the turbines 7 and 8, in particular the low-pressure turbine. This is a bladed sector within the meaning of the invention, therefore comprising a single blade, even if the invention may relate to a multi-bladed sector, comprising a single root and several blades secured to this root in succession in the circumferential direction.

[0051] Only one of the blades will be described below, but they are preferably all of the same or similar design within the turbine wheel. Here, the blade 20 is shown without a heel at its tip.

[0052] Conventionally, the blade 20 comprises, in a radial direction of span 22 of this blade going radially from the inside to the outside, a blade root 24, a stilt 26, a platform 28 and a blade 30 constituting the aerodynamic part of the blade. The blade root 24 has an external shape called a "fir tree", allowing it to be mounted in a corresponding cell opening at the radially external periphery of a turbine disk intended to carry the moving blades, as will be described below. The stilt 26 usually has a small thickness in a circumferential direction 32, while the platform 28 also extends on either side of the stilt 26 in this same circumferential direction 32.More precisely, the platform 28 extends circumferentially beyond a pressure side wall 19 and an extrados side wall 21 of the blade 30, and also extends beyond a leading edge 16 and a trailing edge 17 of the blade, in an axial direction 41, parallel to the axis X of the turbojet engine. Moreover, it is noted that the radial span direction 22 of the moving blade 20 also corresponds to the radial direction of the moving wheel and of the turbojet engine in relation to the axis X, and the same is true for the other two directions 32, 4L.

[0053] The blade 30 has a twisted shape around an axis 27 called the span axis, substantially perpendicular to the axis of rotation of the rotor carrying the blade, this axis of rotation corresponding to the longitudinal axis X of the turbojet. Its leading edge 16 is substantially parallel to the radial span direction 22, and located upstream or forward of the blade in relation to the direction 5 of circulation of the gases in the turbomachine. It also comprises a trailing edge 17 substantially parallel to the leading edge 16, and spaced from the latter along the axis X to be downstream or behind the blade. It also comprises a top 29, also called apex wall 29, substantially parallel to the base of the blade and substantially orthogonal to the radial direction of span 22, according to which the base and the apex wall 29 are spaced from each other. The apex wall 29 can form an external cavity open radially towards the outside, called a bathtub.

[0054] The two main walls of the blade 30 are formed by a first external blade wall, or extrados wall 21, externally forming an extrados aerodynamic surface 21a of the blade, and a second external blade wall, or intrados wall 19, externally forming an intrados aerodynamic surface 19a of the blade. The intrados 19 and extrados 21 walls are spaced from each other while being joined at the leading edge 16, at the trailing edge 17, and at the apex wall which therefore connects these two walls 19, 21.

[0055] [Fig.2A] shows a portion of a movable bladed wheel 34 of the turbine, comprising a rotor disk 33 rotating about the axis of rotation X, as well as a plurality of blades 20 (only one visible in [Fig.2A]). The blade root 24 of each blade is mounted in a corresponding cell 36, opening at the periphery of the disk 33. In a known manner, cooling air from the upstream part of the turbojet engine can be channeled into the space defined between the bottom of the cell 36 of the disk, and a radially internal end face 15 of the blade root 24, before joining one or more cooling air circuits formed through the blade.

[0056] With reference to Figures 3 and 4 showing a first preferred embodiment of the invention, the blade 20 is shown in a nominal unstressed configuration, that is to say when the turbine wheel is not rotating. It is shown that the blade 30 comprises an internal cavity 42, giving it a hollow character. This internal cavity 42 proves to be relatively substantial, since it is delimited, in the radial direction 22, respectively by the apex wall 29 and an external radial end of Péchasse 26. It is also delimited circumferentially by the two intrados 19 and extrados 21 walls, each preferably of small, homogeneous or substantially homogeneous thickness.

[0057] The blade 20 is equipped with a dynamic damping device 50, of the type comprising one or more friction members housed in the internal cavity 42 of the blade 30. This device for damping the vibrations of the blade is particular to the invention, and it will be described in detail below.

[0058] The blade is preferably made at least partly from CMC materials, and even more preferably made entirely of CMC material. Other embodiments nevertheless remain possible, such as the production of this blade in a single piece from a foundry of a metallic material, preferably produced using the lost wax casting technique, known to those skilled in the art.

[0059] In the following, a dynamic damping device 50 will be described equipped with a first friction member 52 intended to cooperate with the extrados wall 21 of the blade, as well as a second friction member 152 intended to cooperate with the intrados wall 19 of the blade. However, the invention could be implemented with a greater number of friction members cooperating with the external walls 19, 21 of the blade, or even with only one of the two aforementioned friction members.

[0060] The first friction member 52 extends radially inside the internal cavity 42, from a fixed internal radial end 54 to a free external radial end 56. The internal radial end 54 of this first member 52 is integral with the external radial end of Péchasse 26, in the internal radial bottom of the cavity 42. The free external radial end 56 is intended to rub against an internal friction surface 58 of the extrados wall 21. Nevertheless, in the nominal unstressed configuration of the blade 20, the free external radial end 56 is preferably close to this internal surface 58, a small clearance 60 remaining provided between these two elements. This small clearance 60 can also be observed all along the first member 52 in the radial direction 22, the fixed internal radial end 54 then also being spaced from the internal friction surface 58 of the extrados wall 21.Alternatively, even in the nominal unstressed configuration of the blade 20, the free external radial end 56 may bear against the internal friction surface 58 of the extrados wall 21.

[0061] The first member 52 preferably has a radial or substantially radial orientation within the internal cavity 42, extending over a large part of the height thereof. As an indicative example, the first friction member 52 extends over a radial height “Hr” greater than or equal to 60% of the total radial height “HT” of the blade 30, this percentage being able to be much higher, for example around 80%. Furthermore, the fixed internal radial end 54 of the first member 52 could be located radially lower than the base of the blade 30, for example by being connected within the Péchasse 26, or even within the blade root 24 which would then be partially hollowed out.

[0062] As best seen in [Fig. 4], the first friction member 52 has a curved shape towards the first extrados wall. To do this, the first friction member 52 is delimited by a convex surface 62 facing the internal friction surface 58, as well as an opposite concave surface 64 delimiting a hollow 66 of this domed shape. The two convex and concave surfaces 62, 64 connect at their ends, to form two opposite ends 68 of the member 52 in a skeleton direction 72 of the blade. It is the line or the fictitious plane 70 connecting these two opposite ends 68, each running along the entire length of the first friction member 52 in the radial direction, which defines the opening of the hollow 66 open in the direction of the intrados wall 19. In cross-section like that of [Fig.4], the fictitious plane 70 defining the opening of the hollow 66 is locally substantially parallel to the skeleton direction 72.

[0063] The hollow 66 thus also opens all along the first member 52 in the radial direction, and within this same hollow, is the center of gravity 74 of the first member 52. The center of gravity 74 is consequently offset from a center of curvature 76 of the first friction member 52, which here has a cross-section of general shape in the form of an arc of a circle, and more preferably in a semicircle. The center of curvature 76, also called the center of gyration, is thus located on the fictitious opening plane 70 of the hollow 66 defined by the first friction member 52. It is noted that the section of the first member 52 has a shape and dimensions that are preferably identical or similar all along this member.

[0064] The particular location of the center of gravity 74 inside the hollow 66, namely offset from the center of curvature 76 in the direction of the extrados wall 21, makes it possible to obtain the dynamic damping function by friction. Indeed, in operation when the mobile wheel rotates around the axis X, the first friction member 52 is subjected to the centrifugal effect. The aforementioned offset of the center of gravity inside the hollow has the consequence of generating on this first member 52 a centrifugal force with not only a radial component towards the outside, but also a circumferential / tangential component leading this member 52 to deform, in the manner of a bending-torsion.This causes the friction-free outer radial end 56 to undergo the greatest circumferential displacement within the first member 52, until this end 56 is forced into abutment against the friction-free inner surface 58 of the extrados wall 21, after the clearance 60 has been consumed. Such a configuration is shown in Figures 5 and 6.

[0065] The circumferential / tangential support 78 observed between the two surfaces 58, 62, combined with the differential displacements likely to be observed between the wall 21 and the member 52 of different stiffnesses, allows the damping device 50 to contribute to the dissipation of energy, thus advantageously reducing the vibration level. As an indication, in operation, the aforementioned differential displacements can be observed in the event of oscillating movement of the external walls 19, 21 of the blade 30.

[0066] The domed shape of the first friction member 52 provides circumferential support differential 78 greatly limiting the risks of damage and injury. Indeed, this local support 78 at the free end 56 is preferentially surface, resulting from the crushing of an initial linear contact between the two concave and convex curved surfaces 58, 62, of different curvatures.

[0067] The second friction member 152 of the dynamic damping device 50 is associated with the intrados wall 19, and has a design identical or similar to that of the first member 52. Thus, in the figures, the technical characteristics of the first member 52 which are found in an identical or similar manner on the second member 152, have on the latter the same numerical references to which the number “1” has been added before it.

[0068] Consequently, the second friction member 152, shown in Figures 3 to 6, is associated with the reference numerals 152 to 178, in application of the rule set above on the reference numerals. It is arranged downstream of the first friction member 52, namely closer to the trailing edge 17, and therefore offset from this first member 52 in the direction of the skeleton 72 in the direction going from the leading edge 16 to the trailing edge 17. It is noted that the orientation of the second member 152 is different from that of the first member 52, given that it has a curved shape in the direction of the intrados wall 19, so as to delimit an open hollow 166 in the direction of the extrados wall 21, all along this second member 152 in the radial direction. In addition, the second friction member 152 has a center of gravity 174 located inside the hollow 166, therefore on the side of the internal friction surface 158 of the intrados wall 19.

[0069] Consequently, in operation, the second friction member 152 deforms towards the intrados wall 19, due to the position of the center of gravity 174 inside the hollow 166.

[0070] According to a second preferred embodiment shown in [Fig.7], the first friction member 52 has a cross-section of general shape in the form of a portion of an ellipse, here in a half-ellipse cut along its major axis, comparable to the fictitious opening plane 70 of the hollow 66 defined by this first friction member 52.

[0071] Similarly, in this second preferred embodiment, the second friction member 152 has a cross-section whose general shape is a curve of radius evolving along it. In this regard, it is noted that other shapes are possible for the cross-section of the first and second friction members 52, 152, and that the shapes retained are not necessarily identical for the two friction members within the internal cavity 42 of the blade. For example, it may be a section of general U or C shape, always in the unstressed configuration of the blade.

[0072] In all cases, the fictitious planes 70, 170 defining the openings of the hollows 66, 166 are preferably locally substantially parallel to the skeleton direction 72.

[0073] According to a third preferred embodiment shown partially in [Fig. 8], in its middle portion located furthest from the opening 70 of the hollow 66, therefore corresponding to the portion located closest to the friction surface 58 of the extrados wall 21, the first friction member 52 comprises an excess thickness 80 which accentuates the physical phenomenon described above, which further improves the dynamic damping. For example, this excess thickness 80 can be located at the free external radial end of the first friction member 52. An identical or similar design can be retained for the second friction member, without departing from the scope of the invention.

[0074] According to a fourth preferred embodiment shown in Figures 9 and 10, the blade 20 comprises a support 82 carrying the first and second friction members 52, 152, to form an assembly 84 which can be manufactured separately from the rest of the blade, then assembled there subsequently. Indeed, the support 82 is housed and fixed in a support receiving cavity 86 made through the root 24 and Péchasse 26, to open on one side into the internal blade cavity 42, and on the opposite side onto the radially internal end face 15 of the root 24.

[0075] The receiving cavity of the support 86, of a shape complementary to that of the support 82, can advantageously correspond to that of a preform around which the blade would have been woven, then removed to leave room for this receiving cavity of the support 86. Then, the assembly 84 is introduced into the cavity 86, radially outwards from the radially internal end face 15 of the root, until the friction members 52, 152 are correctly in place in the internal cavity 42. The method ends with the fixing of the assembly 84 to the rest of the blade. This design advantageously makes it easier to manufacture this blade.

[0076] Of course, various modifications may be made by those skilled in the art to the invention which has just been described, solely by way of non-limiting examples and within the limits of the scope of the appended claims. In particular, the technical characteristics of the various preferred embodiments and their alternatives are interchangeable and / or cumulative.

Claims

Claims

1. A bladed sector (20) for a mobile wheel of an aircraft turbomachine module, the sector comprising a root (24) and at least one hollow blade (30) arranged outwardly relative to the root in a radial direction (22) of this sector, the blade comprising an internal cavity (42) delimited by a first external blade wall (21) externally forming a first aerodynamic surface (21a) corresponding to one of a lower surface and an upper surface of the blade, as well as a second external blade wall (19) externally forming a second aerodynamic surface (19a) corresponding to the other of the lower surface and the upper surface of the blade, the sector being equipped with a dynamic damping device (50) comprising a first friction member (52) housed in the internal blade cavity (42), characterized in that the first friction member (52) extends radially inside the internal blade cavity (42),from a fixed internal radial end (54), to a free external radial end (56) of friction against an internal friction surface (58) of the first external blade wall (21), the first friction member having a domed shape in the direction of the first external blade wall (21), so as to delimit a hollow (66) open in the direction of the second external blade wall (19) all along the first friction member in the radial direction (22), the first friction member (52) having a center of gravity (74) located inside said hollow (66) of this first member.,

2. Bladed sector according to claim 1, characterized in that the first friction member (52) has a convex surface (62) facing the internal friction surface (58) of the first external blade wall (21), as well as an opposite concave surface (64) delimiting the hollow (66).

3. Bladed sector according to claim 1 or claim 2, characterized in that the first friction member (52) has a cross-section of general shape in: - C or U; or - arc of a circle, preferably a semicircle; or - portion of an ellipse, preferably a semi-ellipse; or - curve of evolving radius.

4. A bladed sector according to any one of the preceding claims, characterized in that the fixed internal radial end (54) of the first friction member (52) is spaced from the internal friction surface (58) of the first external blade wall (21), and in that in a nominal unstressed configuration of the bladed sector, the free external radial end (56) of the first friction member (52) bears against the internal friction surface (58) of the first external blade wall (21), or close to this internal surface (58).

5. Bladed sector according to any one of the preceding claims, characterized in that the first friction member (52) extends over a radial height (Hr) greater than or equal to 60% of the total radial height (HT) of the blade (30).

6. Bladed sector according to any one of the preceding claims, characterized in that the first friction member (52) has an excess thickness (80) at the level of its portion located furthest from an opening (70) of the hollow (66) formed by this first member.

7. A bladed sector according to any one of the preceding claims, characterized in that the dynamic damping device (50) is equipped with a second friction member (152) extending radially inside the internal blade cavity (42), from a fixed internal radial end (154), to a free external radial end (156) for friction against an internal friction surface (158) of the second external blade wall (19), the second friction member (152) having a domed shape in the direction of the second external blade wall (19), so as to delimit a hollow (166) open in the direction of the first external blade wall (21) all along the second friction member in the radial direction (22), the second friction member (152) having a center of gravity (174) located inside said hollow (166) of this second member.

8. Bladed sector according to any one of the preceding claims, characterized in that it forms a blade (20), or a sector comprising several blades integral with the root.

9. Bladed sector according to any one of the preceding claims, characterized in that it comprises a support (82) carrying the first friction member (52), the support (82) being housed and fixed in a cavity for receiving the support (86), opening onto a radially internal end face (15) of the foot (24).

10. Aircraft turbomachine (1) comprising at least one bladed sector (20) according to any one of the preceding claims.

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