BLADE COMPRISING A DYNAMIC DAMPING DEVICE, BLADED WHEEL AND CORRESPONDING TURBOMACHINE.

Abstract

The invention relates to a blade (3) configured to be mounted on a bladed wheel (20) of an aircraft turbomachine (1), said bladed wheel (20) comprising several blades (3) following one another in a circumferential direction (23) of said bladed wheel (20) so as to form an annular row of blades (3), said blade (3) comprising: a blade (33) having an aerodynamic profile; a foot (31) extending at a radially internal end of said blade (33) and configured to be mounted in a groove which opens at the external periphery of said disc (22); a radially internal platform (32) separating said blade (33) from said foot (31);a heel (34) extending to a radially external end of said blade (33), said heel (34) comprising a radially external platform (40) from which extend radially outwards an upstream flap (340) and a downstream flap (341), characterized in that said blade (3) further comprises a dynamic damping device (5) positioned at the location of said heel (34) and configured to cooperate by friction with a lateral face (30') of a circumferentially adjacent blade (3') so as to dampen dynamic stresses at the level of said heel (34).

Description

Title of the invention: BLADE COMPRISING A DYNAMIC DAMPING DEVICE, BLADED WHEEL AND CORRESPONDING TURBOMACHINE. Scope of the invention

[0001] The present invention relates to the field of aircraft turbomachinery, and more specifically to the design of the bladed wheels forming the turbines and compressors of these turbomachinery.

[0002] It relates more specifically to the dynamic damping by friction of the blades, which follow 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. Prior art

[0004] Aircraft turbomachinery compressors and turbines are formed by an axial succession of fixed and rotating bladed wheels, also called stator bladed wheels and rotor bladed wheels. In the case where such a bladed wheel is angularly segmented, that is, along the circumferential direction of the wheel, it is usually necessary to limit the vibrational stresses on the blades arranged adjacently along the circumferential direction of the wheel.

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

[0006] Another, more conventional solution involves implementing a contact friction technology between the heels of adjacent blades with specific shapes. This technology, also known as "pretorsion," is characterized by a specific cut on the two opposing circumferential faces of the heel, with a protrusion on the upper surface and a complementary shape on the lower surface. The paired interaction of these circumferential faces allows the two adjacent heels to be held relative to each other in the axial direction. This pretorsion technology is also referred to by the English term "interlock."

[0007] During the assembly of 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 slips at the level of the circumferential faces of the heels, which, coupled with the contact pressures, create damping by friction.

[0009] With this technology, the contact force between the blade tips can vary during turbomachine operation. This variation can result from the natural rotation of the blade around its twist axis (clockwise or counterclockwise), or from the relative movement of adjacent tips in the circumferential direction (moving closer together or further apart). During blade assembly, it is necessary to take these possible variations into account during operation and to ensure that the target contact force is achieved at high speeds, i.e., at the speed where dynamic damping is primarily desired. This can lead to applying a very high contact force during blade assembly, resulting in significant static overstresses that can weaken the blades and / or reduce their service life. This drawback is more or less significant depending on the material used and its ability to withstand such stresses.For example, with blades made of ceramic matrix composite material, also known as CMC material, the permissible mechanical deformations often remain small, making the blades poorly tolerant of this pretorsion principle. Thus, positioning the blades on the wheels proves problematic because it typically requires significant deformation to position all the blades circumferentially. Furthermore, when a blade is made of CMC material, it may be incompatible with the need to apply strong pretorsion to the assembly, required for satisfactory damping at the desired speed.

[0010] Other dynamic damping solutions are known, such as adding friction elements to the interface between the heels, at the level of their circumferential faces which cooperate in pairs. These solutions generally have the disadvantage of generating aerodynamic disturbances at the level of the groove. Description of the invention

[0011] The invention aims to remedy at least in part the disadvantages mentioned above relating to prior art techniques.

[0012] To this end, the invention relates to a blade configured to be mounted on a bladed wheel of an aircraft turbomachine, said bladed wheel comprising a disc on which said blade is intended to be mounted so that several blades succeed one another in a circumferential direction of said bladed wheel so as to form an annular row of blades, said blade comprising: - a blade with an aerodynamic profile; - a foot extending to a radially internal end of said blade and configured to be mounted in a groove which opens onto the outer periphery of the disc; - a radially internal platform separating said blade from said foot; - a heel extending from a radially external end of said blade, said heel comprising a radially external platform from which extend radially outwards an upstream slat and a downstream slat.

[0013] According to the invention, said blade further comprises a dynamic damping device positioned at the location of said heel and configured to cooperate by friction with a lateral face of a circumferentially adjacent blade so as to dampen dynamic stresses at the level of said heel.

[0014] The invention thus provides a simple, reliable, efficient and low mass solution to the problems previously outlined, and whose principle makes it possible to create a damping of dynamic stresses at the level of the heel while freeing oneself from the constraints of prior art solutions.

[0015] Furthermore, by duplicating the principle of the invention on several sets of two adjacent blades of the wheel, or even on the entire bladed wheel, it is possible to reduce the axial leakage section on the entire bladed wheel and thus improve the performance of the stage.

[0016] According to a particular aspect of at least one embodiment of the invention, said heel comprises a housing cut into one of said upstream and downstream slits and opening at said lateral face of said heel so as to be positioned opposite said lateral face of said circumferentially adjacent blade when said blade is mounted on the disc, and said dynamic damping device comprises a friction element movably mounted in said housing between: - a friction position in which said friction element is at least partly in said housing, and is in contact with said lateral face of said circumferentially adjacent blade when said blade is mounted on said disc, so that said friction element cooperates by friction with said lateral face of said circumferentially adjacent blade; - a position set apart in which said rubbing element is at least partly in said housing, and is at a distance from said lateral face of said blade circumferentially adjacent when said blade is mounted on said disc.

[0017] According to a particular aspect of at least one embodiment of the invention, said rubbing element is made from a material including ceramic or a ceramic matrix composite material.

[0018] According to a particular aspect of at least one embodiment of the invention, the rubbing element has a shape defined by a maximum dimension DI and a minimum dimension D2, with a ratio between the maximum dimension DI and the minimum dimension D2 less than or equal to 10, preferably less than or equal to 5.

[0019] According to a particular aspect of at least one embodiment of the invention, the rubbing element has a shape among a cylindrical shape, an ellipsoidal shape, a berlingot shape.

[0020] According to a particular aspect of at least one embodiment of the invention, said housing is hollowed out by electro-erosion sinking.

[0021] According to a particular aspect of at least one embodiment of the invention, said housing is hollowed out in a direction inclined with respect to a direction tangential to said heel.

[0022] According to a particular aspect of at least one embodiment of the invention, said dynamic damping device comprises a second formed housing opening into the other of said upstream and downstream slats such that said second housing opens at the level of said lateral face of said heel, and said dynamic damping device further comprises a second friction element movably mounted in said second housing between: - a friction position in which said second friction element is at least partly in said second housing, and is in contact with said lateral face of said circumferentially adjacent blade when said blade is mounted on said disc, so that said second friction element cooperates by friction with said lateral face of said circumferentially adjacent blade; - a position set apart in which said second rubbing element is at least partly in said second housing, and is at a distance from said lateral face of said blade circumferentially adjacent when said blade is mounted on said disc.

[0023] The invention also relates to a bladed wheel for an aircraft turbomachine, said bladed wheel comprising a disc and several blades according to one of the aforementioned embodiments mounted on said disc, the blades succeeding one another in a circumferential direction of said bladed wheel so as to form an annular row of blades. Furthermore, for two given blades, a first of said two blades comprises a dynamic damping device positioned at said heel and configured to cooperate by friction with a lateral face of said second of the two blades which is circumferentially adjacent so as to dampen dynamic stresses at the level of said heel of said first of said two blades.

[0024] The invention also relates to an aircraft turbomachine comprising a bladed wheel according to the aforementioned embodiment. Presentation of the figures

[0025] The invention, as well as its various advantages, will be more easily understood in the light of the following description of an illustrative and non-limiting embodiment thereof, and the accompanying drawings, among which:

[0026] [Fig-1] illustrates a schematic longitudinal cross-sectional view of a turbomachine aircraft according to the invention;

[0027] [Fig.2] illustrates a more detailed perspective view of a bladed wheel of a low-pressure turbine of the turbomachine according to a first embodiment of the invention;

[0028] [Fig.3] and [Fig.4] illustrate in perspective a portion of a blade according to a first embodiment of the invention;

[0029] [Fig.5] and [Fig.6] illustrate in perspective a portion of a sealing element according to a first embodiment of the invention;

[0030] [Fig.7] is a cross-sectional view of a portion of a blade according to the first embodiment of the invention;

[0031] [Fig.8], [Fig.9] and [Fig. 10] are perspective views of a portion of a bladed wheel illustrating two blades according to the first embodiment of the invention, showing different positions of the sealing element;

[0032] [Fig. 11] illustrates in perspective a portion of a sealing element according to a second embodiment of the invention, and

[0033] [Fig.12], [Fig.13] and [Fig.14] illustrate in perspective a portion of a blade according to a second embodiment of the invention.

[0034] Detailed description of an embodiment of the invention

[0035] With reference first to [Fig. 1], an aircraft turbomachine 1 is shown, according to a preferred embodiment of the invention. This is a twin-spool, turbofan engine. However, it could be a turbomachine of another type, for example a turboprop, without departing from the scope of the invention.

[0036] The turbomachine 1 has a central longitudinal axis 2 around which its various components extend. It comprises, from upstream to downstream along a principal direction 5 of gas flow through this turbomachine, a blower 30, 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. The blower 30 can be driven directly by a low pressure unit comprising the compressor 4 and the turbine 8, or can be driven indirectly by a reducer (not shown).

[0037] Conventionally, after passing through the blower 30, the air splits into a central primary flow 12a and a secondary flow 12b which surrounds the primary flow. The primary flow 12a flows into a main gas circulation channel 14a passing through the compressors 4, 6, the combustion chamber 11 and the turbines 7, 8. The secondary flow 12b, on the other hand, flows into a secondary channel 14b delimited radially outwards by an engine casing, surrounded by a nacelle 9.

[0038] Each turbine 7, 8 and each compressor 4, 6 comprises, in a conventional manner known to those skilled in the art, an alternation of movable bladed wheels and fixed bladed wheels, centered on the axis 2. The invention lies in the design of these bladed wheels, and more particularly in the principle of dynamic damping which is implemented therein.

[0039] A first embodiment of a bladed wheel 20 is now presented in relation to [Fig. 2], and a first embodiment of a blade is presented in relation to Figures 3 to 10. This wheel is preferably intended to form part of the low-pressure turbine 8. However, the invention can be applied to the high-pressure turbine 7, or to one of the two compressors 4, 6. Furthermore, it can be a fixed bladed wheel, without departing from the scope of the invention.

[0040] The bladed wheel 20 comprises a disc 22, centered on the axis 2 and on which are mounted, radially outwards, a plurality of distinct blades 3 forming an annular row of blades.

[0041] As illustrated in [Fig.2], and partially in Figures 3 and 4, each blade 3 comprises: - a blade 33 with an aerodynamic profile; - a foot 31 extending to a radially internal end of the blade 33 and configured to be mounted in a groove which opens onto the outer periphery of the disc 22; - a radially internal platform 32 separating the blade 33 from the foot 31; - a heel 34 extending to a radially external end of the blade 33, this heel 34 comprising a radially external platform 40 from which extend radially outwards an upstream slat 340 and a downstream slat 341.

[0042] According to the invention, the blade 3 further comprises a dynamic damping device positioned at the location of the heel 34 and configured to cooperate by friction with a lateral face of a circumferentially adjacent blade 3A, as illustrated in particular in figures 8 to 10, in order to cushion dynamic stresses at the level of said heel 34.

[0043] More particularly, in this embodiment, the dynamic damping device includes a friction element 50 mounted movably in a housing 51 formed opening onto a lateral face of the heel 34 so as to be positioned opposite the lateral face of the circumferentially adjacent blade 3A when the blade 3 is mounted on the bladed wheel 20.

[0044] Here, and as more particularly illustrated in figures 3 and 4, the housing 51 is hollowed out in the downstream lip 341 so that this housing opens at the level of the lateral face of the heel.

[0045] However, according to other embodiments, it could be provided that the housing is dug into one of the upstream and downstream sluices.

[0046] It could also be envisaged that a housing is carved into each of the two slits, as presented later in connection with the second embodiment.

[0047] As can be seen more particularly in [Fig.7], this housing 51 has a substantially rectangular parallelepiped shape and is hollowed out in a direction inclined with respect to a direction tangential to the heel 34.

[0048] In other words, in this embodiment the housing 51 forms a non-zero angle with a horizontal plane of the blade foot.

[0049] Depending on the embodiment, this angle can be between 25° and 65° with respect to a horizontal plane of the blade foot.

[0050] Such a range has the advantage of allowing the friction element to slide within the housing and of preventing the housing from becoming stuck. In other words, such a range of values ​​makes it possible to obtain a compromise between, on the one hand, the damping effect of the lateral force, and on the other hand, the radial bulk of the blade due to the angle of the housing and the friction element.

[0051] It should be noted that housing 51 can preferably be excavated by electro-erosion sinking.

[0052] This friction element is mounted movably in the housing 51 between: - a friction position in which this friction element 50 is at least partly in the housing 51, and is in contact with the lateral face of the circumferentially adjacent blade 3A when the blade 3 is mounted on the disk 22, so that the friction element 50 cooperates by friction with the lateral face of the circumferentially adjacent blade 3A; - a position set apart in which the friction element 50 is at least partly in the housing 51, and is at a distance from the lateral face of the circumferentially adjacent blade 3A when said blade 3 is mounted on the disc 22.

[0053] This friction element is therefore mounted freely at least along one axis of rotation and along one axis of translation so as to be able to move between the friction position and the spread-away position.

[0054] This housing 51 is calibrated in depth, and also in play with respect to the friction element 50, in order to guarantee the retention of the friction element regardless of the relative movement of the blades with respect to each other and in order to guarantee the free movement of the friction element in the housing 51.

[0055] Thus, for the bladed wheel 20 of an aircraft turbomachine 1, for two given adjacent blades 3, 3A, a first of the two blades 3 includes a dynamic damping device positioned at the location of the heel 34 and configured to cooperate by friction with a lateral face of the second of the two blades 3A which is circumferentially adjacent so as to dampen dynamic stresses at the level of the heel 34 of the first of the two blades 3.

[0056] Figures 8 to 10 show different positions of this rubbing element 50 in the housing 51 and with respect to the circumferentially adjacent lateral face of the blade.

[0057] In each of these positions, the rubbing element 50 is always at least partly in the housing 51, and partly outside of this housing 51.

[0058] In the embodiment presented, the rubbing element 50 is made from a material including ceramic or a ceramic matrix composite material.

[0059] It has, as illustrated in figures 5 and 6, a shape defined by a maximum dimension DI and a minimum dimension D2, with a ratio between the maximum dimension DI and the minimum dimension D2 less than or equal to 10, preferably less than or equal to 5.

[0060] As can be seen in figures 5 and 6, this element may have a rectangular prism shape with rounded edges.

[0061] More particularly, and also as can be seen in figures 5 and 6, this rubbing element 50 has a berlingot shape.

[0062] However, according to other embodiments, the rubbing element could have a shape among a cylindrical shape, an ellipsoidal shape, or can also be a rubbing element 50' having a berlingot shape as shown in [Fig.1 1].

[0063] Thus, its simple geometry and shape ratio make it possible to implement a friction element with optimal robustness and compression performance.

[0064] A second embodiment of the invention is now presented in relation to figures 12 to 14.

[0065] In this second embodiment, the heel 34' comprises a first housing 51' cut into one of the upstream slots 340' and downstream slots 341' and opening at the level of the lateral face of the heel 34' so as to be positioned opposite the lateral face of the circumferentially adjacent blade 3A' when the blade 3' is mounted on the disc 22, and the dynamic damping device includes a friction element 50' mounted movable in the housing 51' between: - a friction position in which the friction element 50' is at least partly in said housing 51', and is in contact with the lateral face of the circumferentially adjacent blade 3A' when the blade 3' is mounted on the disk 22, so that the friction element 50' cooperates by friction with the lateral face of the circumferentially adjacent blade 3A'; - a position set apart in which the rubbing element 50' is at least partly in the housing 51', and is at a distance from the lateral face of the circumferentially adjacent blade 3A' when the blade 3' is mounted on the disc 22.

[0066] As illustrated, the dynamic damping device further comprises a second housing 51' formed opening into the other of the upstream slit 340' and downstream slit 341' so that this second housing 510' opens at the level of said lateral face of the heel 34'.

[0067] Consequently, the dynamic damping device further comprises a second friction element 50' mounted movably in the second housing 51' between: - a friction position in which the second friction element 50' is at least partly in the second housing 51', and is in contact with the lateral face of the circumferentially adjacent blade 3A' when the blade 3' is mounted on the disk 22, so that the second friction element 50' cooperates by friction with the lateral face of the circumferentially adjacent blade 3A'; - a spread-out position in which the second rubbing element 50' is at least partly in the second housing 51', and is at a distance from the circumferentially adjacent blade lateral face 3A' when the blade 3' is mounted on the disk 22.

Claims

Demands

1. Blade (3, 3') configured to be mounted on a bladed wheel (20) of an aircraft turbomachine (1), said bladed wheel (20) comprising a disc (22) on which said blade (3, 3') is intended to be mounted such that several blades (3, 3') follow one another in a circumferential direction (23) of said bladed wheel (20) so as to form an annular row of blades (3, 3'), said blade (3, 3') comprising: - a blade (33) having an aerodynamic profile; - a foot (31) extending from a radially internal end of said blade (33) and configured to be mounted in a groove which opens into the external periphery of said disc (22); - a radially internal platform (32) separating said blade (33) from said foot (31);- a heel (34, 34') extending to a radially external end of said blade (33), said heel (34, 34') comprising a radially external platform (40) from which extend radially outwards an upstream flap (340, 340') and a downstream flap (341, 341'), characterized in that said blade (3, 3') further comprises a dynamic damping device positioned at the location of said heel (34, 34') and configured to cooperate by friction with a lateral face of a circumferentially adjacent blade (3A, 3A') so as to dampen dynamic stresses at the level of said heel (34, 34').;

2. Blade (3, 3') according to claim 1, characterized in that said heel (34, 34') comprises a housing (51, 51') cut into one of said upstream slot (340) and downstream slot (341) and opening at said lateral face of said heel (34, 34') so as to be positioned opposite said circumferentially adjacent lateral face of said blade (3A, 3A') when said blade (3, 3') is mounted on said disc (22), and in that said dynamic damping device comprises a friction element (50, 50') movably mounted in said housing (51, 51') between: - a friction position in which said friction element (50, 50') is at least partly in said housing (51, 51'), and is in contact with said lateral face of said circumferentially adjacent blade (3A, 3A') when said blade (3, 3') is mounted on said disc (22), so that said friction element (50, 50') cooperates by friction with said lateral face of said circumferentially adjacent blade (3A, 3A'); - a spread-out position in which said friction element (50, 50') is at least partly in said housing (51, 51'), and is at a distance from said lateral face of said circumferentially adjacent blade (3A, 3A') when said blade (3, 3') is mounted on said disc (22).

3. Blade according to claim 2, characterized in that said friction element (50, 50') is made from a material including ceramic or a ceramic matrix composite material.

4. Blade according to any one of claims 2 or 3, characterized in that said friction element (50, 50') has a shape defined by a maximum dimension (Dl) and a minimum dimension (D2), with a ratio between said maximum dimension (Dl) and said minimum dimension (D2) less than or equal to 10, preferably less than or equal to 5.

5. Blade according to any one of claims 2 to 4, characterized in that said friction element (50, 50') has a shape among a cylindrical shape, an ellipsoidal shape, a berlingot shape.

6. Blade according to any one of claims 2 to 5, characterized in that said housing (51, 51') is hollowed out by electro-erosion sinking.

7. Blade (3) according to the preceding claim, characterized in that said housing (51) is hollowed out in a direction inclined with respect to a direction tangential to said heel (34, 34').

8. Blade (3') according to any one of claims 2 to 7, characterized in that said dynamic damping device comprises a second housing (51') formed opening into the other of said upstream blade (340') and downstream blade (341') ​​such that said second housing (510') opens at the level of said lateral face of said heel (34'), and in that said dynamic damping device includes further a second friction element (50') mounted movably in said second housing (51') between: - a friction position in which said second friction element (50') is at least partly in said second housing (51'), and is in contact with said lateral face of said circumferentially adjacent blade (3A') when said blade (3') is mounted on said disc (22), so that said second friction element (50') cooperates by friction with said lateral face of said circumferentially adjacent blade (3A'); - a set-apart position in which said second rubbing element (50') is at least partly in said second housing (51'), and is at a distance from said lateral face of said circumferentially adjacent blade (3A') when said blade (3') is mounted on said disc (22).

9. Bladed wheel (20) of an aircraft turbomachine (1), said bladed wheel (20) comprising a disc (22) and several blades (3, 3') according to any one of claims 1 to 8 mounted on said disc (22), said blades (3, 3') following one another in a circumferential direction (23) of said bladed wheel (20) so as to form an annular row of blades (3, 3'), and in that for any two given blades (3, 3A, 3', 3A'), a first of said two blades (3, 3') comprises a dynamic damping device positioned at said heel (34, 34') and configured to cooperate by friction with a circumferentially adjacent lateral face of said second of the two blades (3A, 3A') so as to dampen dynamic stresses at said heel (34, 34') of the said first of the said two paddles (3, 3').

10. Turbomachine (1) for aircraft comprising a bladed wheel according to claim 9.

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