EP2971609B1 - Turbine ring for a turbomachine - Google Patents

Description

FIELD OF THE INVENTION

The present disclosure relates to a turbomachine turbine ring, in particular for a helicopter.

Such a ring can be used for any type of turbomachine to reduce vibratory behaviors that may appear within such rings.

STATE OF THE PRIOR ART

In a conventional helicopter turbomachine, the high pressure turbine rings generally comprise a ring of sectors fixed on a ring support. As is visible on the FIG 2 , the sectors have for this purpose hooks capable of cooperating with hooks of the support.

In contact with the air stream, the ring sectors are subjected to the stresses of the aerodynamic flow, caused in particular by the wake of the upstream and downstream stages, and can thus experience a vibratory behavior. In particular, in the operating range of the motor, the sectors are likely to come into resonance, which can lead to cracking due to vibration fatigue or premature wear phenomena.

To date, in order to better control such vibratory behaviors, one way to improve is to rework the geometry of the sectors themselves. However, the design of ad hoc geometries is complex because of the mechanical and aerodynamic constraints imposed.

Another known solution, easier to implement, is to reduce the games in the assembly of the rings. However, the radial clamping between the sectors and the support leads to additional mechanical stress at the fastening hooks which can, therefore, know significant plastic deformation, or even cracking. In addition, such an operation complicates the mounting procedure of the rings, thereby increasing the cost of production and maintenance.

There is therefore a real need for a turbine ring, and a turbomachine, which are lacking, at least in part, the disadvantages inherent in the aforementioned known configurations.

PRESENTATION OF THE INVENTION

The present disclosure relates to a turbine ring according to claim 1, comprising a support, substantially cylindrical, and one or more sectors forming a ring configured to materialize a section of air stream, each sector being fixed on the support by a device of in which the hooking device comprises a hook portion belonging to the support and projecting towards the sector, and a hook portion belonging to the sector and projecting towards the support, the hook parts of the support and the sector being configured to cooperate in order to secure the sector on the medium; the ring further comprises a damping device provided within the coupling device and radially constrained between a portion of the sector and a portion of the support so as to damp the relative movements of the sector relative to the support; the damping device is in alternating contact, in the circumferential direction, with the inner surface of the support and the outer surface of the hook portion of the sector.

Thus, thanks to this damping device which maintains at least one pressure zone on said portion of the sector and at least one pressure zone on said portion of the support, the relative movements of the sector and the support are constrained and therefore less important. In addition, they are quickly damped by friction of the sector and / or the support against the damping device. As these friction dissipate the energy of the sectors, this one does not accumulate any more, which reduces the risk of resonances of the sectors over the operating range and thus strongly limits the damages by vibratory fatigue.

In addition, thanks to this damping device which elastically constrains the relative movements of the sector and the support, it is possible to maintain a radial clearance between the sector and the support sufficient to limit the mechanical stresses of fatigue type oligocyclic s' exercising on the sector and the support, thus prolonging their life.

This damping device also frees the sector of its secondary objective of limiting vibrations. From then on, his geometry can be chosen more freely: it can be simplified, resulting in cost savings, or optimized more effectively with respect to other functions in the sector.

In addition, this damping device allows easy assembly of the sector on the support by acting as a guide whose radial dimension substantially corresponds to the clearance to separate the sector of the support: the sector can be pressed against the damping device for ensure its precise positioning. This provides increased accuracy and repeatability of positioning, resulting in particular better control of the game at the top of the blade and reducing machining nonconformities.

Such a configuration in which the damping device is in contact alternately, in the circumferential direction, with the inner surface of the support and the outer surface of the hook portion of the sector provides a simple shaping of the damping device, this last not having to ensure a permanent and simultaneous contact with the inner surface of the support and the outer surface of the hook portion of the sector.

In some embodiments, the damping device is further configured to press a portion of the sector against a portion of the support. Therefore, the relative movements of the sector and the support can also be damped by friction of the sector against the support.

In some embodiments, the support is also fixed via a second hooking device similar to the first attachment device; it is also equipped with a second damping device, provided in the second attachment device, similar to the first damping device.

In some embodiments, the damping device comprises a flexible blade. Preferably, this flexible blade is a sheet metal element. Such a flexible sheet is inexpensive, easy to form, and has a stiffness adapted to such damping.

In some embodiments, the damping device is constrained radially between said portion of the sector and said portion of the support over its entire length. Therefore, the constraints on the sector and support are spread over the entire length of the sector. In addition, depreciation is homogeneous across the sector.

In some embodiments, the damping device is substantially smooth over its entire length with the exception of localized recesses distributed along its length. It may especially be spherical impressions made by stamping, for example.

In other embodiments, the device comprises a corrugated sheet element.

In some embodiments, the damping device is provided between an outer surface of the sector hook portion and an inner surface of the carrier. Such a configuration is easy to assemble. In addition, in this configuration, the two hook parts are pressed against each other which reinforces the attachment of the sector and its damping.

In other embodiments, the damping device is provided between an inner surface of the hook portion of the carrier and an outer surface of the sector.

In some embodiments, the damping device is housed at least in part in a groove made in a portion of the sector. With this groove, it is possible to mount the damping device on the sector before assembly on the support, which facilitates the assembly procedure. In addition, this reduces the radial clearance between the sector and the support.

In other embodiments, the damping device is housed at least partly in a groove made in a portion of the support.

In some embodiments, the cushioning device envelopes at least the distal portion of the hook portion of the carrier. The damping device is thus easily put in place and remains in position even in the absence of the sector.

In some embodiments, the damping device is configured to continuously maintain at least one pressure zone on the outer surface of the hook portion of the support and a pressure zone on its inner surface, on the one hand , and at least one pressure zone on the inner surface of the sector hook portion and / or a pressure zone on an outer surface of the sector, other share. The damping device is thus clipped around the end of the hook, which ensures its positioning and its immobilization.

In other embodiments, the damping device envelopes at least the distal portion of the sector hook portion.

In some embodiments, the damping device is integral and continuous along the circumference of the ring formed by the sector or sectors. It can, however, be interrupted by a break in an azimuthal plane of the device.

In other embodiments, the damping device is divided into a plurality of sections succeeding each other along the circumference of the ring formed by the sector or sectors.

In some embodiments, a section of the damping device is associated with each sector.

In other embodiments, each section of the damping device is associated with a plurality of sectors.

In some embodiments, the damping device is configured to further provide a seal between the support and the sector. It may be for example a braided seal.

In some embodiments, the damping device is secured to either the sector or the support. This joining is preferably performed by welding.

The present disclosure also relates to a turbomachine comprising at least one ring according to any one of the aforementioned embodiments.

In some embodiments, the turbomachine is a helicopter turbine engine. Said ring equips the linked turbine and / or the free turbine.

In some embodiments, the turbomachine is an airplane turbojet engine.

The above-mentioned characteristics and advantages, as well as others, will appear on reading the following detailed description of embodiments of the ring and the proposed turbomachine. This detailed description refers to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings are schematic and are intended primarily to illustrate the principles of the invention.

• La FIG 1 est une vue d'ensemble d'un exemple de turbomoteur d'hélicoptère.
• La FIG 2 est une vue en perspective écorchée d'un premier exemple d'anneau de turbine.
• La FIG 3 est une vue en coupe axiale de l'anneau de la FIG 2.
• La FIG 4 illustre une variante de l'anneau de la FIG 2.
• La FIG 5 est une vue en perspective écorchée d'une autre variante de l'anneau de la FIG 2.
• La FIG 6A illustre une variante de dispositif d'amortissement.
• La FIG 6B est une vue en coupe radiale de l'anneau de la FIG 2 munie du dispositif d'amortissement de la FIG 6A.
• La FIG 7A illustre une autre variante de dispositif d'amortissement.
• La FIG 7B est une vue en coupe radiale de l'anneau de la FIG 2 munie du dispositif d'amortissement de la FIG 7A.
• La FIG 8A est une vue en coupe axiale d'un deuxième exemple d'anneau.
• Les FIG 8B et 8C sont des vues en coupe axiale de variantes de l'anneau de la FIG 8A.
• La FIG 9 est une vue en coupe axiale d'un troisième exemple d'anneau.

In these drawings, from one figure (FIG) to the other, identical elements (or element parts) are identified by the same reference signs. In addition, elements (or parts of elements) belonging to different exemplary embodiments but having an analogous function are indicated in the figures by incremented numerical references of 100, 200, etc.

• The FIG 1 is an overview of an example of a helicopter turbine engine.
• The FIG 2 is a broken perspective view of a first example of a turbine ring.
• The FIG 3 is an axial sectional view of the ring of the FIG 2 .
• The FIG 4 illustrates a variant of the ring of the FIG 2 .
• The FIG 5 is a broken perspective view of another variant of the ring of the FIG 2 .
• The FIG 6A illustrates an alternative damping device.
• The FIG 6B is a radial sectional view of the ring of the FIG 2 equipped with the damping device of the FIG 6A .
• The FIG 7A illustrates another variant of damping device.
• The FIG 7B is a radial sectional view of the ring of the FIG 2 equipped with the damping device of the FIG 7A .
• The FIG 8A is an axial sectional view of a second ring example.
• The FIG 8B and 8C are axial sectional views of variants of the ring of the FIG 8A .
• The FIG 9 is an axial sectional view of a third ring example.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

In order to make the invention more concrete, examples of turbine rings are described in detail below with reference to the accompanying drawings. It is recalled that the invention is not limited to these examples.

The FIG 1 illustrates a turbomachine 10, in this case a helicopter turbine engine. In a conventional manner, this turbine engine 10 comprises a compressor 11, a gas generator 12 and linked turbines 13 and free 14, also called high pressure turbine and low pressure turbine, driven in rotation by the flue gas flow exiting the combustion chamber 12. The free turbine 14 comprises a turbine wheel 14a which is fixed at one end of the combustion chamber. a shaft 15. At the other end of the shaft 15 is a primary gear 16 which meshes with an intermediate gear 17. This intermediate gear 17 meshes with an output gear 18. The intermediate gear 17 and the pinion output 18 are gear wheels which form part of the speed reducer of the turbomachine 10. The output gear 18 is connected to an output shaft 19 intended to be coupled to the main gearbox of the helicopter (not shown right here). The linked turbine 13, comprising a turbine wheel 13a, is in turn connected to the compressor 11 via a drive shaft 20. The linked turbine 13 is further equipped with a turbine ring 30 which materializes the vein of air vis-à-vis the blades of the turbine wheel 13a.

The FIG 2 illustrates a first example of such a turbine ring 30. This comprises a generally cylindrical ring support 31, forming an integral part of the turbine casing 13, and a ring sector ring 32 fixed on the support of ring 31 so as to materialize the air stream of the turbine 13.

As is best seen on the FIG 3 each ring sector 32 is fixed on the ring support 31 by means of attachment devices 33a and 33b: in each attachment device 33a, 33b, a hook 34 of the sector 32 extends towards the support 31 to cooperate with a hook 35 of the support 31 extending towards the ring sector 32. These hooks 34 of the sector 32 thus have a radial portion 34a and a tangential portion 34b and extend continuously along each sector 32. The hooks 35 of the support 31 also have a radial portion 35a and a tangential portion 35b and extend circumferentially continuously along the circumference of the support 31.

In this first embodiment, the hooks 34 of the sector 32 are provided with a rib 41 projecting on the outer surface 34e of the hook 34 in the extension, at least partially, of the radial portion 34a of the hook 34. This rib 41 allows to play a game radial between the outer surface 34e of the hook 34 and the inner surface 31i of the support 31 to set up a damper 50.

This damper 50 is a flexible blade, preferably a metal sheet, taking substantially the shape of a V in this axial section plane: this sectional shape is substantially constant over the entire length of the damper 50. The damper 50 is thus constrained between the outer surface 34e of the hook 34 of the sector 32 and the inner surface 31i of the support 31 in such a way that it exerts, on the one hand, a pressure on the hook 34 by its central zone and, on the other hand, part, a pressure on the support 31 by its 2 ends.

The stiffness of this damper 50 can be adjusted by adjusting the thickness, the length and more generally the shape of the damper. In particular, in this example, the damper is made using a sheet of thickness about 0.2mm. Its material can also be chosen according to the desired stiffness. In this case, this sheet is a plate Inconel 718.

As is visible on the FIG 2 in this example, the damper 50 of each attachment device 33a, 33b is integral and continuous all along the ring support 31 with the exception of a break in an azimuthal plane of the damper 50 of however, in other examples, the damper could be continuous all along the ring support without hyphenation.

Many variants of this first exemplary embodiment are possible. For example, in the variant of the FIG 4 , a groove 42 is hollowed in the outer surface 34e of the hook 34 of the ring sector 32. Such a groove 42 can accommodate the damper 52. The depth of the groove 42 is nevertheless smaller than the height of the damper 52 so that the damper 52 protrudes above the outer surface 34e of the hook 34: the damper 52 is constrained between the support 31 and the hook 34 of the sector 32.

In addition, the FIG 4 illustrates that it is also possible to mount the damper 52 in a head-to-tail position relative to that of the damper 50 of the FIG 3 : then, the damper 52 exerts a pressure on the inner surface 31i of the support 31 by its central zone while it exerts a pressure on the hook 34 of the sector 32 by its two ends.

The FIG 5 illustrates another variant of the first embodiment of the ring 30. In this variant, the damper 54 is not monobloc but divided: in this case, the divisions of the damper 54 are provided to correspond to the divisions of the ring sectors 32 such that a damper section 54 is associated with each sector 32. However, it goes without saying that the damper 54 could be divided otherwise.

The FIG 6A and 6B illustrate yet another variant of the first example of a turbine ring 30. Unlike the example of the FIG 3 , the damper 56 is not here shaped along its length. Indeed, in this variant, the damper 56 is a flexible blade, preferably a metal sheet, substantially smooth over its entire length with the exception of recesses 57 made regularly in its smooth surface. As is visible on the FIG 6B , the damper 56 is configured so that its outer surface bears against the inner surface 31i of the ring support 31 while the inner end of these recesses 57 bears against the outer surface 33e of the hook 33 the ring sector 32 so that the damping device 56 is in alternating contact, in the circumferential direction, with the inner surface 31i of the support 31 and the outer surface 33e of the hook 33 of the ring sector 32.

The FIG 7A and 7B illustrate a last variant of the first example of a turbine ring 30. In this variant, the damper 58 is a corrugated sheet whose oscillations allow the damper 58 to be in contact alternately, in the circumferential direction, with the surface internal 31i of the support 31 and the outer surface 34e of the hook 33 of the ring sector 32.

The FIG 8A illustrates a second example of turbine ring 130. In this second example, the damper 160 is a flexible blade, preferably a metal sheet, substantially in the shape of a U in this axial torque plane, engaged around the distal portion of the hook 135 of the support 131, that is to say at the end of the tangential portion 135b of the hook 135. The damper 160 thus comprises a flat portion 161, pressed against the distal surface of the hook 135, which extend the two branches of the damper 160. In a first portion 162, the two branches are tightened so as to grip the distal portion of the hook 135 and then, in a second portion 163, the two branches depart to come rely on the inner surface 134i of the tangential portion 134b of the hook 134 on the one hand, and on the outer surface 132e of the ring sector 132 on the other. In this example, the two branches of the damper 160 are symmetrical.

The FIG 8B illustrates a variant of the second example of a turbine ring 130. In this variant, in order to obtain a different stiffness, the internal branch of the damper 160 is longer than its external branch. Thus, the second portion 163 of the inner branch rests on the outer surface 132e of the ring sector 132 further downstream than in the example of FIG. FIG 8A .

The FIG 8C illustrates another variant of the second example of a turbine ring 130. In this variant, the internal branch of the damper 160 comprises a first constricted portion 162 which bears against the inner surface 135i of the hook 135 but does not have a second portion bearing against the outer surface 132e of the ring sector 132.

The FIG 9 illustrates a third example of turbine ring 230. In this third example, the damper 260 is a flexible blade, preferably a metal sheet, taking substantially the shape of an L in this axial section plane, engaged around the distal portion of the hook 234 of the ring sector 232. The damper 260 comprises a flat portion 261, pressed against the radial portion 235a of the hook 235 of the ring support 231, which extends a generally tangential branch. In a first portion 262, this branch tapers inwards so as to abut against the outer surface 234e of the hook 234 of the sector 232, then in a second portion 263, this branch deviates towards the outside of so as to come to rest on the inner surface 231i of the support 231. Finally, this branch folds radially inward so as to bear at right angles against the outer surface 234e of the hook 234. The hook portion 234 of the sector 232 is thus pressed against the hook portion 235 of the support 231.

The modes or examples of embodiment described in this presentation are given by way of illustration and not limitation, a person of the profession can easily, in view of this presentation, modify these modes or embodiments, or consider others, while remaining within the scope of the invention.

In particular, all the described embodiments relate to the turbine connected to the turbomachine, but these teachings can also be applied to the free turbine. Likewise, these teachings are directly transposed to the field of aircraft turbojets.

In addition, the various features of these modes or embodiments can be used alone or be combined with each other. When combined, these features may be as described above or differently, the invention not being limited to the specific combinations described herein. In particular, unless otherwise specified, a characteristic described in connection with a mode or example of embodiment may be applied in a similar manner to another embodiment or embodiment.

Claims (10)

1. A turbine ring comprising:

   a cylindrical support (31); and

   one or more sectors (32) forming a circle configured to define a segment of an air passage, each sector (32) being fastened to the support (31) by an attachment device (33a, 33b);

   wherein the attachment device (33a) comprises a hook portion (35) belonging to the support (31) and projecting towards the sector (32), and a hook portion (34) belonging to the sector (32) and projecting towards the support (31), the hook portions of the support and of the sector (34, 35) being configured to co-operate in order to fasten the sector (32) to the support (31);

   the ring being characterized in that it further comprises a damper device (50) provided within the attachment device (33a) and stressed radially between a portion (34e) of the sector and a portion (31i) of the support so as to damp relative movements between the sector (32) and the support (31); and

   in that the damper device (56) comes into contact in alternation, in the circumferential direction, with the inner surface of the support (31) and with the outer surface of the hook portion of the sector (32).
2. A ring according to claim 1, characterized in that the damper device comprises a flexible blade (50), preferably an element made of sheet metal.
3. A ring according to claim 1 or claim 2, characterized in that the damper device (50) is stressed radially between said portion (34e) of the sector and said portion (31i) of the support over its entire length.
4. A ring according to any one of claims 1 to 3, characterized in that the damper device (50) is provided between an outer surface (34e) of the hook portion (34) of the sector (32) and an inner surface (31i) of the support (31).
5. A ring according to any one of claims 1 to 4, characterized in that the damper device (52) is received at least in part in a groove (42) formed in a portion (34e) of the sector (32).
6. A ring according to any one of claims 1 to 3, characterized in that the damper device (160) enfolds at least the distal portion of the hook portion (135) of the support (131).
7. A ring according to claim 6, characterized in that the damper device (160) is configured so as to maintain permanently, firstly at least one pressure zone on the outer surface of the hook portion (135) of the support (131) and a pressure zone on its inner surface, and secondly at least one pressure zone on the inner surface (134i) of the hook portion (134) of the sector (132) and/or a pressure zone on an outer surface (132e) of the sector (132).
8. A ring according to any one of claims 1 to 3, characterized in that the damper device (260) enfolds at least the distal portion of the hook portion (234) of the sector (232).
9. A ring according to any one of claims 1 to 8, characterized in that the damper device (54) is divided into a plurality of sections that follow one another all along the circumference of the circle formed by the sector(s) (32), a section preferably being associated with each sector (32).
10. A turbine engine including at least one ring (30) according to any preceding claim.

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