Turbo machine blade assembly

Abstract

The present invention relates to a blade arrangement for a turbomachine, in particular a gas turbine, comprising a first blade (10-12) having a first blade (10) and a first platform (11), and a circumferentially adjacent second blade (20-22) having a second blade (20) and a second platform (21), wherein a first wall (12) of the first blade and a second wall (22) of the second blade define a blade cavity in which a damper (30) with a wall-side contact surface (31, 32) is arranged, wherein this contact surface has at least a first surface section (31) that is convexly curved in a first direction (K) which, in at least one contact position where the first surface section contacts the first wall, is parallel to at least one section of an edge (k) of the first platform facing the second platform.

Description

[0001] The present invention relates to a blade arrangement for a turbomachine, in particular a gas turbine, a turbomachine, in particular a gas turbine, with the blade arrangement, and a method for reducing vibrations of the blade arrangement.

[0002] Blades of turbomachinery can exhibit various vibration modes during operation. In particular, so-called flap modes ("F-mode") of the blades can cause them to tilt around the main axis or axis of rotation of the turbomachine, while so-called couple-disk modes ("CD-mode") cause them to pitch in the direction of a dividing line between the platforms.

[0003] Various examples of damping elements are known from documents EP2455587A1, EP3098387A1, EP2738353A2 and US20180187562A1.

[0004] One objective of an embodiment of the present invention is to reduce vibrations of blade assemblies.

[0005] This problem is solved by a blade arrangement having the features of claim 1 or a method having the features of claim 7. Claim 6 protects a turbomachine with one or more blade arrangements described herein. Advantageous embodiments of the invention are the subject of the dependent claims.

[0006] According to one embodiment of the present invention, (at least) a blade arrangement for a turbomachine, in one embodiment a gas turbine, in particular an aircraft engine, comprises a blade with a blade and at least one platform, and a further blade with a blade and at least one platform arranged adjacent to it in the circumferential direction, wherein these two blades are hereby designated, without limitation of generality, as first and second blades, and their blade and platform accordingly as first blade or first platform (of the first blade) or second blade or second platform (of the second blade).

[0007] In one embodiment, the blades are rotor blades and / or blades of a compressor or turbine stage of a gas turbine, in particular of an aircraft engine, and / or have blade feet which are attached, in particular detachably and / or by positive and / or frictional engagement, to a support, in particular rotor of the turbomachine, or are provided for this purpose, in particular arranged, or are used.

[0008] Due to the operating conditions, the present invention can be used here to a particular advantage.

[0009] According to one embodiment of the present invention, a wall of the first blade ("first wall") and a wall of the second blade ("second wall") define a blade cavity in which a one- or multi-part damper is or is arranged, which has a wall-side contact surface that, during operation, at least temporarily contacts the first and second walls or is provided, in particular arranged, or used for this purpose.

[0010] According to one embodiment of the present invention, this contact surface has a surface section, which is hereby designated, without limitation of generality, as the first surface section, and which is convexly curved in a first direction (viewed) that, in at least one contact position in which this first surface section contacts the first wall, is parallel to at least one section of an edge, namely a blade-side or flow-channel-side or upper edge, of the first platform facing the second platform. In other words, the contact surface has a first surface section that is convexly curved in the direction of at least one section of an edge of the first platform facing the second platform (blade-side or flow-channel-side or upper edge) or of a dividing line between the first and second platforms when the damper orits first surface section is in the contact position.

[0011] In one embodiment, this section of the edge comprises at least 10%, and in particular at least 25%, of the total length of the edge or dividing line; in another embodiment, it comprises at least 50%, and in particular, it may also comprise 100%. In one embodiment, the dividing line may be gap-like, in particular to compensate for tolerances, thermal expansion, movement, or the like. Accordingly, in one embodiment, the edge of the first platform (facing the second platform) does not touch the second platform (during normal operation), or is designed to do so, in particular, by means of a specific configuration. In another embodiment, the edge of the first platform (facing the second platform) and the second platform may touch at least temporarily, so that the dividing line forms a contact line between the first and second platforms.Thus, in one embodiment, the first direction in the at least one contact position, in which the first surface section contacts the first wall, is parallel to at least one section of a separating line between the first and second platforms, in particular a section of a temporary or even only virtual or theoretical contact line between the first and second platforms (defined by the edge of the first platform facing the second platform), wherein this section in one embodiment is at least 10%, in particular at least 25%, in one embodiment at least 50% of a (total) length of the separating or (temporary or (only) virtual or theoretical) contact line, and in particular can also be 100%.

[0012] As explained in the introduction, couple-disk modes can cause the blades or platforms to nod in the direction of the dividing line. By having the damper or its contact surface convexly curved in the first surface section parallel to at least one section of the edge of the first platform facing the second platform, or of the dividing line defined by this, vibration energy can be advantageously dissipated in one embodiment by a frictional sliding motion of the damper or its contact surface as a result of a (thus facilitated) relative movement of the first and second blades relative to each other, thereby reducing corresponding vibrations of the blade assemblies.

[0013] In a first embodiment according to the invention, the first surface section is additionally convexly curved in the circumferential direction (as seen) when the damper is in the contact position.

[0014] As explained in the introduction, flap modes can cause the blades or platforms to tilt about the main axis or axis of rotation, or circumferentially. By having the damper or its contact surface convexly curved in the circumferential direction in the first surface section, vibrational energy can be advantageously dissipated in one embodiment by a frictional sliding motion of the damper or its contact surface, resulting from a relative movement of the first and second blades relative to each other (which is thus facilitated), thereby reducing corresponding vibrations of the blade assemblies.

[0015] In a second embodiment according to the invention, the first surface section is straight in the circumferential direction (as seen) when the damper is in the contact position.

[0016] In one design, this can make sliding movement between the first surface section and the first wall more difficult, or increase the contact area, allowing the damper to be better supported against the first wall.

[0017] In particular, especially with regard to the flap modes mentioned above or the tilting of the blades or platforms about the main or rotation axis or in the circumferential direction, it is provided according to the invention that the contact surface has a further surface section, which is referred to here without limitation of generality as the second surface section, which contacts the second wall when the damper is in the contact position, or is provided for this purpose, in particular is arranged or is used, and is then convexly curved in the circumferential direction (as seen) in the contact position.

[0018] In one embodiment, this can promote tilting of the blades or platforms around the main or rotational axis or in the circumferential direction, and thus advantageously dissipate vibrational energy from flap modes through a (thereby promoted) frictional sliding movement of the damper or its contact surface, thereby reducing corresponding vibrations of the blade arrangements.

[0019] In the second embodiment according to the invention, the damper can advantageously be supported on the first wall by means of the first surface section, which is straight in the circumferential direction (as seen) in the contact position, as explained.

[0020] In the first embodiment according to the invention, a second surface section of the contact surface is provided, which in the contact position contacts the second wall and is straight in the first direction and / or in the circumferential direction (as viewed). This second surface section can, in particular, be flat or planar.

[0021] In one design, this can make sliding movement between this second surface section and the second wall more difficult, allowing the damper to be better supported against the second wall.

[0022] In one embodiment, the damper has one or more damper cavities in which (each) at least, in a preferred embodiment exactly, a shock body, in one embodiment spherical, is arranged or is arranged, which in operation makes shock contacts with the damper cavity wall or is provided for this purpose, in particular is equipped or is used.

[0023] This is based on a concept, fundamentally known from WO 2012 / 095067 A1, for reducing blade vibrations through impact contacts, which can in particular detune the resonance frequencies of blade (arrangements).

[0024] As has surprisingly been found, in combination with the contact surface described above, impulses between impact elements, dampers, and blades can be transmitted particularly advantageously, thereby reducing blade vibrations. It is assumed that this is particularly facilitated by the sliding movements in the corresponding directions, which are either promoted or hindered by this surface, although this assumption is not definitively binding.

[0025] In one embodiment, the shock body(s) is / are or will be arranged in an airtight or gas-tight manner in the (respective) damper cavity.

[0026] This allows for a particularly advantageous reduction of blade vibrations caused by impact contact.

[0027] In one embodiment, the damper cavities (each, in particular together) are closed by a cover, in one embodiment airtight, which is arranged on a side of the damper opposite the contact surface.

[0028] This allows the momentum transfer between impact bodies, dampers and blades to be (further) improved in one design.

[0029] The first and second platforms are, in one design, paddle-foot-side platforms, in particular radially internal and / or under-platforms.

[0030] Additionally or alternatively, the bucket cavity is arranged in one embodiment on a side of the first and / or second platform facing away from the blade blade, or in another embodiment wholly or partially in the first and / or second platform.

[0031] It has surprisingly turned out that this reduces blade vibrations particularly effectively.

[0032] In one embodiment, an axial direction is parallel to a rotary or (main) machine axis of the turbomachine, a circumferential direction corresponds to a direction of rotation around this axis, and a radial direction is perpendicular to the axial and circumferential directions.

[0033] Further advantageous embodiments of the present invention will become apparent from the dependent claims and the following description of preferred embodiments. The following is shown, in part schematically: Fig. 1 a blade assembly according to an embodiment of the present invention in radial top view; Fig. 2 a blade of the blade assembly in perspective view; Fig. 3 a damper of the blade assembly in enlarged perspective view; Fig. 4 a section along line AA in Fig. 1 ; Fig. 5 the damper from another perspective; and Fig. 6 a section along line VI-VI in Fig. 4 .

[0034] Fig. 1 shows a blade arrangement according to an embodiment of the present invention in a radial top view, Fig. 2 One of the two identical blades of the blade assembly in perspective view.

[0035] Both buckets each have a blade 10 or 20 and a platform 11 or 21 on the bucket foot side.

[0036] In a scoop cavity in the two platforms, which are defined by corresponding walls 12 and 22 respectively (see Fig. 4 ) is limited, a damper 30 is arranged, on whose wall-side contact surface one can in Fig. 3 looks.

[0037] This contact surface has a first surface section 31 which is convexly curved in a first direction K, which is in a contact position in which the first surface section contacts the wall of one of the blades (cf. Fig. 4 ), parallel to the edge k of the first platform 11 facing the second platform 21 or dividing line between the first and second platform. Fig. 6 shows, for clarification, a section along the in Fig. 4 Section line VI-VI, indicated by a dash.

[0038] In the exemplary embodiment, the first surface section in the contact position is also convexly curved in the circumferential direction U, and the contact surface has a second surface section 32 which, in the contact position, contacts the wall of the other blade and is straight in the first direction K and in the circumferential direction U.

[0039] In a variation not shown, conversely, the first surface section 31 in the contact position is straight in the circumferential direction U and the second surface section 32 is convexly curved in the circumferential direction.

[0040] As seen in the rear view (from radially below) of the Fig. 5 As can be seen, the damper 30 has several damper cavities 33, each containing a (in Fig. 5 (Hidden) impact body is arranged for impact contact with the respective damper cavity wall.

[0041] The damper cavities are / are formed by a (in Fig. 5 (Hidden) lid airtight.

[0042] Although exemplary embodiments were explained in the preceding description, it should be noted that a multitude of modifications are possible. Furthermore, it should be emphasized that the exemplary embodiments are merely examples and are not intended to restrict the scope of protection, applications, or structure in any way. Rather, the preceding description provides the skilled person with a guideline for implementing at least one exemplary embodiment, whereby various modifications, particularly with regard to the function and arrangement of the described components, can be made without departing from the scope of protection as defined in the claims. Reference symbol list

[0043] 10. First blade 11. First platform 12. First wall 20. Second blade 21. Second platform 22. Second wall 30. Damper 31. First surface section 32. Second surface section 33. Damper cavity k Edge Kerste direction U Circumferential direction

Claims

1. Blade arrangement for a turbomachine, in particular a gas turbine, comprising a first blade (10-12) having a first airfoil (10) and a first platform (11), and a second blade (20-22), adjacent in the peripheral direction (U), having a second airfoil (20) and a second platform (21), a first wall (12) of the first blade and a second wall (22) of the second blade defining a blade cavity in which a damper (30) having a wall-side contact surface (31, 32) is arranged, this contact surface having at least a first surface portion (31) that is convexly curved in a first direction (K) which, in at least one contact position in which the first surface portion contacts the first wall, is parallel to a dividing line between the first and second platform, such that, as a result of a relative movement of the first and second blades against one another in the direction of the dividing line due to a frictional sliding movement of the contact surface of the damper in the direction of the dividing line, vibrational energy can be dissipated, and thus corresponding vibrations in the direction of the dividing line of the blade arrangements can be reduced, characterized in that, in the contact position, the first surface portion is also convexly curved in the peripheral direction and the contact surface has at least a second surface portion (32) which contacts the second wall in the contact position and is planar and / or is straight in the first and / or peripheral direction or the contact surface has at least a second surface portion (32) which, in the contact position, contacts the second wall and is convexly curved in the peripheral direction, and the first surface portion (31) is straight in the peripheral direction in the contact position, such that, as a result of a relative movement of the first and second blades against one another in the peripheral direction due to a frictional sliding movement of the contact surface of the damper in the peripheral direction, vibrational energy can be dissipated, and thus corresponding vibrations in the peripheral direction of the blade arrangements can be reduced.

2. Blade arrangement according to claim 1, characterized in that the damper has at least one damper cavity (33) in which at least, in particular exactly, one impact body is arranged, in particular airtightly, for impact contact with the damper cavity wall.

3. Blade arrangement according to claim 2, characterized in that the damper cavity is closed, in particular airtightly, by a cover, which is arranged on a side of the damper opposite the contact surface.

4. Blade arrangement according to any of the preceding claims, characterized in that the first and second platform are blade root-side platforms.

5. Blade arrangement according to any of the preceding claims, characterized in that the blade cavity is arranged on a side of the first and / or second platform which faces away from the airfoil, in particular is arranged at least partially in said platform.

6. Turbomachine, in particular a gas turbine, comprising at least one blade arrangement according to any of the preceding claims.

7. Method for reducing vibrations of a blade arrangement according to any of claims 1 to 5, characterized in that a blade arrangement according to any of claims 1 to 5 is provided and the damper is arranged in the blade cavity such that it can assume the contact position.

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