Blade of a turbine

Abstract

The invention relates to a turbine blade (13) for a turbomachine, comprising a turbine blade airfoil (14) extending radially, said turbine blade airfoil (14) having a leading edge (16) axially upstream and a trailing edge axially downstream, a radially outer platform (15) having an upstream end (17) and a downstream end, said radially outer platform (15) further comprising at least one lip (18, 19) extending radially towards the outside, the radially outer end (20) of the leading edge (16) of the turbine blade airfoil (14) and / or of the trailing edge of the turbine blade airfoil (14) extending axially upstream in relation to the upstream end (17) of the platform (15) and / or, respectively, extending downstream in relation to the downstream end of the platform (15), characterized in that the blade (13) has at least one partition (21) extending radially towards the outside from the radially outer end of the turbine blade airfoil (14) and axially between the leading edge (16) and the upstream end (17) of the platform (15) and / or, respectively, between the trailing edge and the downstream end of the platform (15).

Description

DOMAIN

[0001] The present invention relates to a turbine blade for a turbomachine, such as for example an aircraft turbojet. CONTEXT

[0002] Document FR 2 970 999 in the name of the Applicant discloses a turbine bladed wheel comprising a turbine disc on which blades 1 are mounted. Each blade 1 extends radially and comprises a radially internal root 2, mounted in a cell of the disc, a profiled blade 3, separated from the root 2 by a radially internal platform 4. A radially external platform 5 extends from the radially external end of the blade 3. The radially external platform 5 comprises wipers 6 extending radially outwards which cooperate with an abradable material so as to form a labyrinth seal.

[0003] The external platform 5 comprises an axially upstream end 7 and an axially downstream end 8 located respectively upstream and downstream of the leading edge 9 and the trailing edge 10 of the blade 3.

[0004] In order to lighten the blades 1, it is envisaged to remove a part of the radially external platform 5 by forming openings at the level of said external platform 5. However, in such a case, a part of the air flow can be diverted from the intrados zone 11 to the extrados zone 12 by passing radially outside the blade 3, through the openings. Such recirculation is detrimental to the efficiency of the turbine and it is therefore appropriate to limit it. US2015 / 226070A1 shows the technical characteristics of the preamble of independent claim 1. SUMMARY OF THE INVENTION

[0005] The invention aims in particular to provide a simple, effective and economical solution to this problem.

[0006] For this purpose, the invention relates to a turbine blade for a turbomachine intended to extend around an axis of the turbomachine, the blade comprising a blade extending radially relative to the axis between a radially inner platform and a radially outer platform, the blade comprising an axially upstream leading edge and an axially downstream trailing edge, a radially outer platform comprising an upstream end and a downstream end, the radially outer platform comprising at least one lip extending radially outward, characterized in that the radially outer end of the leading edge of the blade and / or the trailing edge of the blade extends axially upstream relative to the upstream end of the platform and / or respectively downstream relative to the downstream end of the platform, and in that the blade comprises at least one partition extending radially outward from the radially outer end of the blade,and axially between the leading edge and the upstream end of the platform, and / or respectively between the trailing edge and the downstream end of the platform, the partition extends radially outwards over only part of the radial dimension of the lip or substantially up to the radially external end of the lip.,

[0007] The removal of the upstream and / or downstream ends from the leading edge and / or from the trailing edge makes it possible to limit the axial dimension of the external platform, and therefore the mass of the blade.

[0008] Furthermore, the presence of a partition, extending radially outwards and extending axially, i.e. along the axis of the turbine, between the leading edge of the blade and the upstream end of the platform and / or respectively between the trailing edge and the downstream end of the platform, constitutes at least in part an obstacle to air recirculation. Since these recirculations generate aerodynamic losses, such partitions also make it possible to improve the efficiency of the turbine.

[0009] The partition may extend axially between the leading edge and an upstream surface of the lip and / or respectively between the trailing edge and a downstream surface of the lip.

[0010] Such a partition prevents any recirculation of air radially outside the external platform.

[0011] According to another feature, the partition may extend radially outwardly substantially to the radially outer end of the wiper.

[0012] Thus, the partition prevents air recirculation along the entire length of the lip which, in cooperation with the abradable material, ensures sealing against air passage.

[0013] Furthermore, the partition may extend radially outward over only a portion of the radial dimension of the lip.

[0014] Thus, the presence of the partition opposing the recirculation of air, the limitation of its radial dimension to only a part of the radial dimension of the wiper makes it possible to control the addition of material, and therefore to control the mass of the blade.

[0015] The radial distance between the radially outer end of the partition and the radially outer end of the wiper is for example between 1 and 10 mm.

[0016] The partition may extend in a direction forming an angle with the radial direction.

[0017] Such an inclination of the partition makes it possible to improve the position of the partition so that it opposes the direction of air recirculation from the intrados to the extrados.

[0018] The angle is for example between 30° and 60°.

[0019] According to another characteristic, the partition may comprise an upstream and / or respectively downstream end edge, rectilinear and forming an angle with the radial direction.

[0020] Such an inclination makes it possible to reduce the volume of the partition, and therefore to control the mass of the material added to the turbine blade.

[0021] The angle is for example between 0° and 60°.

[0022] Additionally, the lip may extend along a plane, with at least a portion of the partition extending perpendicular to the plane of the lip.

[0023] Therefore, the partition extends partly perpendicular to the lip.

[0024] In particular, the wiper may extend along a plane, at least a portion of the partition extending along a plane forming an angle with the axis of the turbomachine.

[0025] The axis of the turbomachine corresponds to the axis of the rotor on which the blades are fixed.

[0026] The partition is thus inclined in the direction of the blade rotation, so as to form a deflector for the air flow. Such a position thus effectively limits the recirculation of air from the intrados to the extrados.

[0027] The said angle is for example between 30° and 60°.

[0028] According to another characteristic, the partition can be curved, for example concave seen from the lower surface of the blade.

[0029] The invention also relates to a turbomachine turbine comprising a bladed wheel comprising turbine blades as described previously.

[0030] The invention also relates to a turbomachine, such as for example an aircraft turbojet, characterized in that it comprises such a turbine.

[0031] The invention will be better understood and other details, characteristics and advantages of the invention will appear on reading the following description given by way of non-limiting example with reference to the appended drawings. BRIEF DESCRIPTION OF THE FIGURES

[0032] there figure 1 is a schematic view of a prior art turbine blade; figure 2 is a schematic view of an exemplary turbine blade platform according to one embodiment of the invention; figures 3A à 4B are perspective views illustrating part of a blade according to different embodiments of the invention. DETAILED DESCRIPTION

[0033] In the following, the terms "upstream" and "downstream" are defined with respect to the direction of gas flow in the turbomachine, in particular in the secondary flow path. Similarly, the terms "radial" and "axial" are defined with respect to the axis of the turbine wheel. Each turbine blade extends radially outward from the turbine wheel disc, the axis of rotation of which extends axially.

[0034] Reference is made hereinafter to the figures 2 and following in relation to the invention, the figure 1 , concerning the prior art, having already been described previously.

[0035] There figure 2 illustrates a portion of a turbine blade 13 for a turbomachine according to the invention. Several turbine blades 13 according to the invention are intended to be mounted on a disk so as to form a turbine wheel.

[0036] The blade 13 comprises a radially extending blade 14, and a radially external platform 15 located at the radially external end of the blade 14. The blade 14 comprises an axially upstream leading edge 16 and an axially downstream trailing edge (not shown). The platform 15 comprises an upstream end 17 and a downstream end (not shown). Said platform 15 also comprises wipers, namely an upstream wiper 18 and a downstream wiper 19 in the example illustrated in the figures.

[0037] In the illustrated example, the platform 15 extends axially between the two lips 18, 19 and is perforated relative to the platform 5 of the prior art presented previously. Indeed, the platform 15 does not comprise a part extending axially beyond the lips 18, 19.

[0038] An openwork platform with a portion extending beyond the lip can also be considered.

[0039] In both cases, the radially outer end 20 of the leading edge 16 of the blade 14 extends axially upstream relative to the upstream end 17 of the platform 15. Similarly, the radially outer end of the trailing edge (not shown) of the blade 14 extends axially downstream relative to the downstream end of the platform 15.

[0040] The blade 13 according to the invention further comprises a partition 21. The partition 21 is arranged radially outside the radially external end 20 of the leading edge 16 and / or the trailing edge (not shown) of the blade. Indeed, the partition 21 extends circumferentially opposite the radially external end 20 of the blade 14.

[0041] Furthermore, the partition 21 extends axially between the leading edge 16 and the upstream end 17 of the platform 15, and / or respectively between the trailing edge and the downstream end of the platform 15.

[0042] The partition 21 illustrated extends axially between the leading edge 16 and an upstream surface 22 of the lip 18. Similarly, it is conceivable that the partition 21 extends axially between the trailing edge and a downstream surface of the lip.

[0043] In the embodiment illustrated in figure 2 , the partition 21 extends over only part of the height, that is to say the radial dimension, of the lip 18, 19 concerned.

[0044] The partition 21 has a rectilinear end edge 23 forming an angle α with the radial direction or the radial plane. The angle α is for example between 30° and 90°. The angle α is inscribed in a plane having the axial direction as its normal.

[0045] Several variants of realization are illustrated in figures 3A à 4B .

[0046] The geometric shape and positioning of the partitions 21 may vary depending on the applications.

[0047] In the embodiments illustrated in figures 3A et 4A , the partition 21, 27, extends radially outwards substantially to the radially external end 24, 26 of the wiper 18, 19. In other words, the partition 21, 27 has a height substantially equivalent to that of the wiper 18, 19.

[0048] Preferably, there is a radial operating clearance between the radially external end 25 of the partition 21, 27 and the radially external end 24, 26 of the wiper 18, 19. This operating clearance is for example between 0.5 and 2 mm.

[0049] Such play thus makes it possible to avoid any friction of the partition 21, 27 on the abradable material.

[0050] In the embodiments illustrated in figures 3B et 4B , the partition 21, 27, extends radially outwards over only a part of the radial dimension of the wiper 18, 19.

[0051] In other words, the radially outer end 25 of the partition 21, 27 is offset radially inward relative to the radially outer end 24, 26 of the wiper 18, 19.

[0052] The radial distance between the radially external end 25 of the partition 21, 27 and the radially external end 24, 26 of the wiper 18, 19 is for example between 0.5 mm and 2 mm.

[0053] As illustrated in figures 3A à 4B , the partition 21 located at the level of the upstream lip 18 and the partition 27 located at the level of the downstream lip 19 can extend in a direction forming an angle β with the radial direction.

[0054] The angle β is for example between 0° and 60°.

[0055] The angle β is inscribed in a plane comprising the axial and radial directions.

[0056] It should be noted that, in the variant embodiments of the figures 3A à 4B , the angle α is equal to 0.

[0057] In each variant of the embodiment of the figures 3A et 3B , the upstream partition 21 is perpendicular to the plane of the upstream lip 18.

[0058] Furthermore, in each variant of the embodiment of the figures 4A et 4B , the downstream partition 27 extends, at least in part, along a plane forming an angle θ with the axis X of the turbomachine. Thus, the partition and the wiper each extend radially projecting from the platform of the blade. In particular, the downstream partition 27 is inclined in the direction of the direction of rotation of the blade R, so as to form a deflector for the air flow.

[0059] In other words, the downstream partition 27 is inclined towards the intrados. The inclination towards the intrados is particularly interesting because it makes it more difficult to recirculate air from the intrados area to the extrados area.

[0060] Said angle θ is for example between 0° and 60°.

[0061] In each of the embodiments described above, the partition 21, 27 constitutes an obstacle to recirculation of air from the intrados zone to the extrados zone, and thus makes it possible to reduce the losses linked to such recirculation. This increases the performance of the turbine, while limiting the mass of the blade 14 due to the limited dimensions of the external platform 15.

Claims

1. A turbine blade (13) for a turbomachine intended to extend around an axis of the turbomachine, the blade (13) having a vane (14) extending radially with respect to the axis between a radially inner platform (4) and a radially outer platform (15), the vane (14) comprising an axially upstream leading edge (16) and an axially downstream trailing edge, the radially outer platform (15) comprising an upstream end (17) and a downstream end, the radially outer platform (15) comprising at least one radially outwardly extending seal lip (18, 19), characterised in that the radially outer end (20) of the leading edge (16) of the vane (14) and / or the trailing edge of the vane (14) extends axially upstream relative to the upstream end (17) of the platform (15) and / or respectively downstream relative to the downstream end of the platform (15), and in that the blade (13) has at least one partition (21, 27) extending radially outwards from the radially outer end of the vane (14), and axially between the leading edge (16) and the upstream end (17) of the platform (15), and / or respectively between the trailing edge and the downstream end of the platform (15), the partition (21, 27) extends radially outwards over only part of the radial dimension of the seal lip (18, 19) or substantially to the radially outer end (24, 26) of the seal lip (18, 19).

2. Turbine blade (13) according to claim 1, characterised in that the partition (21, 27) extends axially between the leading edge (16) and an upstream surface (22) of the seal lip (18) and / or respectively between the trailing edge and a downstream surface of the seal lip (19).

3. Turbine blade (13) according to claim 2, characterised in that the partition (21, 27) extends radially outwardly substantially to the radially outer end (24, 26) of the seal lip (18, 19).

4. Turbine blade (13) according to claim 2, characterised in that the partition (21, 27) extends radially outwardly over only part of the radial dimension of the seal lip (18, 19).

5. Turbine blade (13) according to any one of the preceding claims, characterised in that the partition (21, 27) extends in a direction at an angle to the radial direction.

6. Turbine blade (13) according to any one of the preceding claims, characterised in that the partition (21, 27) has an upstream (23) and / or respectively downstream end edge which is straight and forms an angle (a) with the radial direction, the angle (a) lying in a plane normal to the axial direction.

7. Turbine blade (13) according to any one of the preceding claims, characterised in that the seal lip (18, 19) extends in a plane, at least part of the partition (21, 27) extending perpendicularly to the plane of the seal lip (18, 19).

8. Turbine blade (13) according to any one of claims 1 to 6, characterised in that the seal lip (18, 19) extends in a plane, at least part of the partition (21, 27) extending in a plane forming an angle (0) with the axis (X) of the turbomachine.

9. Turbine blade (13) according to one of claims 1 to 8, characterised in that the partition (21, 27) is curved, for example concave as seen from the lower surface of the vane (14).

10. Turbine for a turbomachine, characterised in that it comprises a bladed wheel having turbine blades (13) according to one of claims 1 to 9.

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