EP2696034A1 - Rotor blade assembly for a turbomachine and turbomachine - Google Patents

Abstract

The rotor blade assembly (1) has multiple individual rotor blades (4), which are arranged next to each other in a circumferential direction and are clamped between two rotor disks with their blade roots (6). The clamping elements for clamping the blade roots engage to the rotor disks. The blade roots have an end section (26) in each case, which is thickened on both sides in an axial direction (x). The rotor disks are provided with a corresponding recess in each case for receiving the end section in sections.

Description

The invention relates to a blade assembly for a turbomachine and a turbomachine.

Modern turbomachines such as aircraft engines often have at least one integrally bladed rotor disk. However, the production of this so-called blisk (bladed disk) designated rotor disk is demanding due to the integral design. In addition, a repair of such a rotor disk is complex, since, for example, the removal of a damaged blade and the insertion of a replacement blade due to the integral design manufacturing technology are demanding. An exemplary repair method for replacing a blade is in the patent US Pat. No. 7,458,844 B1 , In the patent application DE 10 2008 057 160 A1 For example, a repair method for replacing an integral disk member is described.

From the European patent application EP 2 392 773 A2 a blade assembly is known in which an integrally bladed rotor ring (bladed ring) is mechanically clamped between two rotor discs. For radially inner support of the rotor ring in the radial direction, the rotor disk, which is viewed in the flow direction, has a multiplicity of integral axial support elements or an integral axial support ring. The radial outer securing of the rotor ring takes place by means of positive engagement between the rotor ring and heads of the rotor disks. However, as with the blisk design, the removal of a damaged blade and the insertion of a replacement blade are complex in terms of manufacturing due to the integral nature of the rotor ring. In addition, the disk heads for holding the blades are projecting, so that it comes to a mass enrichment in this area.

The object of the invention is to provide a blade assembly which overcomes the aforementioned disadvantages, whose geometry is easy to manufacture and which is easy to repair. Furthermore, it is an object of the invention to provide a turbomachine whose blades changed at least one blade assembly with little effort can be.

This object is achieved by a blade arrangement having the features of patent claim 1 and by a turbomachine having the features of patent claim 11.

A rotor blade assembly according to the invention for a turbomachine has a plurality of individual blades which are arranged side by side in the circumferential direction and which are clamped with their blade roots between two rotor disks, wherein clamping elements for clamping the blade roots engage the rotor disks.

Since the blades or blade segments are carried out individually and clamped releasably directly between the rotor discs, a blade exchange or a repair of the blade assembly compared to the integral design is easy to perform. Since the clamping or clamping forces (main forces) are introduced into the blade roots, there is a direct force flow of the main forces in the blade roots and the blades are firmly clamped between the rotor discs. A material abrasion of the blade roots or the rotor disks in the clamping area or fretting is excluded due to the lack of relative movements between the blade roots and the rotor disks. The rotor discs do not require a complex and cantilevered geometry for holding the blades, so that the rotor discs can be formed thin-walled in the head area. In addition, there is a good thermal insulation between the blades and the rotor disks, so that the blade assembly is exposed to only a small thermal load.

In a preferred embodiment, the clamping elements engage the outside, ie opposite to the blades, on the rotor disks and can be supported on a front rotor element and a rear rotor element. The clamping elements are designed as pressure elements in this embodiment. The rotor elements are, for example, with the blade assembly about a common axis of rotation rotating support discs. By supporting the clamping elements on adjacent rotor elements, the rotor disks and thus the rotor blade assembly are additionally stabilized. Alternatively, the clamping elements are not designed as pressure elements, but as tension elements, which can be dispensed with the rotor elements.

Preferably, the blade roots each have an end portion thickened on both sides in the axial direction, and the rotor disks each have a corresponding recess for receiving the end portions. As a result, a positive connection between the blade roots and the rotor discs is created, whereby on the one hand a precise mounting position of the blades between the rotor discs is defined. On the other hand, torques are better transmitted by the positive locking than in a contourless clamping range, so that a tightening torque or clamping or clamping torque can be limited. The centrifugal forces are intercepted via the positive connection under the blades, so that only relatively small holding forces for holding the blades are necessary.

The thickened end portions may each have mutually opposite convex sinusoidal clamping surfaces. The recesses of the rotor disks then each have a complementary sinusoidal inner contour. The sinusoidal toothing further improves the transmission of the torques. Furthermore, the sinusoidal contours are quick and easy to make example by non-round turning. Of course, however, other outer and inner contours are possible. However, rounded or rounded contours and thus contours without sharp edges are preferred.

The clamping elements may be formed integrally with the rotor disks and each having a web with an end-side contact head, each having a contact surface for engagement with the rotor elements. Due to the integral design of the pressure elements with the rotor discs, the number of parts of the blade assembly is reduced. As a result, the assembly can be further simplified and shortened in time. The contact surface thereby enables a large-scale contact with the rotor elements.

Alternatively, the clamping elements may be individual parts, each having a web with two end-side and mutually opposite contact heads, each having a contact surface for engagement with the rotor disks or rotor elements. Due to the separate design of the clamping elements and the rotor disks each of the rotor disks and each of the clamping elements can be identical parts, whereby the variety of parts is reduced. In addition, the manufacture of the rotor discs and the clamping elements is simplified compared to the integral design.

Preferably, the contact surfaces each have an axial elevation and at least the rotor disks each have a corresponding axial recess for receiving the elevations. As a result, a positive connection between the clamping elements and the rotor disks is created, whereby on the one hand a precise installation position of the clamping elements is defined on the rotor disks. On the other hand, the torques are better transmitted by the positive locking than in a contourless design of the clamping elements and the rotor disks, so that the tightening torque can be limited. The centrifugal forces are intercepted via the positive connection under the blades, so that only relatively small holding forces for holding the blades are necessary.

To further improve the torque transmission, the elevations may each have a sinusoidal outer contour and the axial depressions each having a sinusoidal inner contour. The introduction of sinusoidal depressions can be done by turning. Of course, however, other outer and inner contours are possible. However, rounded or rounded contours and thus contours without sharp edges are preferred.

The clamping of the blades can be further improved if the end sections and the clamping elements are arranged at the same radius. As a result, the end portions and the clamping elements are arranged in alignment with each other, so that no bending moments can occur in the clamping area.

For additional thermal insulation, a heat protection element can be arranged between the blade root and the rotor disks. The heat protection element consists for example of a ceramic material and also causes a compensation of component inaccuracies.

A preferred turbomachine has at least one rotor blade arrangement according to the invention, which is clamped between two rotor elements. Since the blades or blade segments are clamped between the rotor discs, they can be easily replaced in the event of damage manufacturing technology.

Other advantageous embodiments of the invention are the subject of further Dependent claims.

In the following, a preferred embodiment of the invention is explained in more detail with reference to a greatly simplified schematic representation. The only FIG. 1 shows an axial section through a disc portion of a blade assembly according to the invention.

In FIG. 1 a section of a rotor blade assembly 1 according to the invention for a turbomachine is shown. The rotor blade assembly 1 can be arranged on the compressor side in an aircraft engine, for example, and thereby rotate about an axis of rotation 2 extending in the axial direction x. It has a plurality of circumferentially juxtaposed individual blades 4, each with its blade root 6 between a viewed in the axial direction x of the blade assembly 1 front rotor disk 8 and a rear rotor disk 10 by means of a front clamping member 12 and a rear clamping member 14 releasably clamped or are releasably clamped. The blade assembly 1 is thus a tensioning rotor.

The rotor blades 4 each have, in addition to a blade root 6, an airfoil 16 and an inner shroud 18 disposed between the blade root 6 and the airfoil 16. The inner shroud 18 is provided with a lateral sealing lip 20 and an opposite lateral sealing groove 22 in the axial direction x. The sealing lip 20 engages each in a sealing groove of an adjacent blade and prevents inter alia a Heizgaseinzug through a side gap between the adjacent blades through (not shown). Alternatively, the sealing lip 20 is formed separately from the inner shroud 18 and thus a later to be installed sealing element strip. Preferred sealing element strips consist of a textile material or a metallic material.

The blade root 6 has a shaft 24 which extends radially inwardly from the inner shroud 18 and has an enlarged end portion 26 relative to the shank 24. The shank 24 has a parallelepipedal shape with two parallel and mutually opposite clamping surfaces (not visible) for engagement with the rotor discs 8 , 10 and with two parallel and mutually opposite side surfaces, of which in the FIG. 1 visible side surface is provided with the reference numeral 28. The clamping surfaces and the side surfaces 28 are each formed plan or contourless.

The end portion 26 is viewed in the axial direction x formed on both sides of the shaft 24 thickened and has an approximately oval cross-section. It has two mutually opposite convex clamping surfaces 30, 32, which are each considered to be sinusoidal in the radial direction z. Thus, the end portion 26 has two sinusoidal outer contours facing away from each other. In addition, the end portion 26 is widened in the transverse direction y relative to the shaft 24, so that it protrudes laterally beyond the side surfaces 28.

The rotor disks 8, 10 are two identical disks with a circular cross section. They each have a the blade roots 6 facing and in abutment with these clamping surface 34 and one opposite to this and the clamping elements 10, 12 facing engagement surface 36. In their midst, the rotor discs 8, 10 each have a hub, not shown for positioning a rotor shaft rotating about the rotation axis 2 (not shown). For receiving the end portions 26 of the rotor blades 4, in each case a correspondingly formed axial annular recess 38, 40 is introduced with a sinusoidal inner contour in the clamping surfaces 34. For example, the annular recesses 38, 40 introduced by non-circular turning. In the assembled state of the rotor disks 8, 10, the annular recesses 38, 40 are arranged opposite one another.

In addition, the rotor discs 8, 10 in each case in the engagement surfaces 36 opposite to their respective annular recess 38, 40 axial annular recess 42, 44. The annular recesses 42, 44 serve to receive axial elevations 46 of the clamping elements 12, 14 and are provided with a sinusoidal inner contour Mistake. They are smaller than the annular recesses 38, 40 formed. For example, the annular recesses 42, 44 are introduced by non-circular turning.

To avoid bending moments in the clamping region of the blade assembly 1, the annular recesses 38, 40 and the annular recesses 42, 44 viewed from the rotation axis 2 from the same radius r. As a result, the end portion 26 and the clamping elements 12, 14 are arranged in alignment with each other.

The clamping elements 12, 14 are arranged in the axial direction x in front of and behind the moving blades 4 and distributed uniformly in the circumferential direction of the moving blade arrangement 1. As in the only one FIG. 1 For example, a moving blade 4 of two clamping elements 12, 14 is clamped between the rotor disks 8, 10. Thus, this blade assembly 1 twice as many clamping elements 12, 14 as blades 4. The clamping elements 12, 14 are in the illustrated embodiment, pressure elements, which are supported on a front rotor element (not shown) and on a rear rotor element (not shown) and the rotor disks 8, 10 compress in the axial direction x. The rotor elements are in particular support disks, which rotate with the rotor disks 8, 10 about the rotation axis 2 and of which one is arranged in front of the rotor blade assembly 1 and one behind the rotor blade assembly 1. The rotor elements are preferably arranged opposite a row of guide vanes and provided on the head side with shrouds and / or inlet liners for sealing a radial gap between the guide blade tips and the shrouds.

Alternatively, the clamping elements 12, 14 are tension elements which contract the rotor disks 8, 10 in the axial direction x. When forming the clamping elements 12,14 as tension elements can be dispensed with the rotor elements for supporting the clamping elements 12, 14.

The front and rear clamping elements 12, 14 are identical. They have an elongated extension with a greater constant extent in the transverse direction y (width) than in the radial direction z (height). In order not to hinder a lateral contact of the rotor blades 4 or an engagement of the sealing lips 20 in the sealing grooves 22 by the clamping elements 12, 14, they have a smaller width than the inner shrouds 18. The clamping elements 12, 14 are to their longitudinal axis and their Transverse axis formed mirror-symmetrical and thus interchangeable with each other during assembly.

For reasons of clarity, only the right in the figure and thus the rear clamping element 14 is provided with reference numerals in the following. In particular, the clamping elements 12, 14 each have an elongated web 48 and two end-side and opposite bearing heads 50, 52. In the embodiment shown in which the clamping elements 12, 14 are physically separated from the rotor disks 8, 10, which is a contact head 50 each have a support head, with which the clamping elements 12, 14 are supported on the respective rotor element. The other contact head 52 is in this embodiment in each case a print head, with which the clamping elements 12, 14 engage the respective rotor disk 8, 10. However, when the clamping elements 12, 14 with their printheads 52nd are integrated into the rotor disks 8, 10, the clamping elements 12, 14 only each have a support head 50 for supporting on the rotor elements.

The contact heads 50, 52 are thickened relative to the web 48 in the radial direction z. They each have one of the rotor elements and the rotor disks 8, 10 facing contact surface 54, 56 and support surface 54 and pressure surface 56. In addition, the contact heads 50, 52 each have an axial elevation 46, 58 on. The elevations 46, 58 are each a web-like bulge of the support surface 54 and the pressure surface 56 with a sinusoidal outer contour. The elevations 46, 58 extend in the transverse direction y and are arranged in the radial direction z of the center of the support surface 54 and the pressure surface 56.

In the assembled state, the rotor blades 4 are arranged with their blade roots 6 between the rotor disks 8, 10, wherein their end portions 26 are arranged in the annular recesses 38, 40 in a form-fitting manner. Thus, the blades 4 are interlocked with the rotor discs 8, 10 by sinusoidal pass contours. Likewise, the clamping surfaces 34 of the rotor disks 8, 10 are in contact with the clamping surfaces of the shank 24. The clamping elements 12, 14 are aligned in the axial direction x parallel to the axis of rotation 2 and are supported with their support heads 50 on the rotor elements. Preferably, a blade 4 is clamped by two clamping elements 12, 14. They engage with their elevations 58 in a form-fitting manner in each case a corresponding annular groove of the rotor elements and are thus interlocked with the rotor elements by means of a sinusoidal passport contour. They press with their printheads 50 against the rotor disks 8, 10 and engage with their elevations 46 in the annular recesses 40, 42 a. Thus, the clamping elements 12, 14 with the rotor discs 8, 10 are each toothed by a sinusoidal contour, so that in combination all interlocking teeth (clamping elements 12, 14 each with rotor element and rotor disk 8, 10, blade 4 with rotor disks 8, 10) the centrifugal forces are virtually intercepted under the blades 4 and only relatively small holding forces for holding the blades 4 are necessary. The support surfaces 54 and the pressure surfaces 56 are flat against the rotor elements or the engagement surfaces 36 of the rotor disks 8, 10. The clamping elements 12, 14 and the end portions 26 are now aligned with each other aligned (see dash-dotted auxiliary line 60), so that the clamping forces are each introduced directly into the respective end portion 26 and bending stresses in the clamping area can be avoided. The blades 4 are fixedly releasably clamped between the rotor discs 8, 10, wherein relative movements between their blade roots and the rotor discs 8, 10 are excluded.

In order to increase the thermal contact resistance between the blade roots 6 and the rotor disks 8, 10, a high-temperature material or heat protection element can be inserted in the blade root area or clamping area. The high-temperature material is ceramic, for example, and prevents or reduces a heat transfer from the rotor blades 4 to the rotor disks 8, 10, so that the rotor disks 8, 10 are virtually thermally insulated and their temperature is lowered. As a result, the rotor disks 8, 10 are formed relatively thin. In addition, the high-temperature material allows compensation of geometrical component inaccuracies.

Instead of the annular recesses 42, 44 and the annular grooves, the rotor disks 8, 10 and rotor elements may also have a plurality of each arranged to a ring pockets into which the clamping elements 12, 14 with their contact heads 50, 52 engage individually. For example, it would then be possible to dispense with the elevations 46, 58, since then a positive connection between the clamping elements 12, 14 and the rotor disks 8, 10 or the rotor elements is already formed by the pockets.

Of course, in particular other rounded accountings as sinusoidal contouring of the elevations 46, 58, the annular recesses 38, 40 and the annular recesses 42, 44 possible.

Disclosed is a blade assembly for a turbomachine, with a plurality of individual blades which are arranged side by side in the circumferential direction and which are clamped with their blade roots between two rotor disks, wherein act on the rotor disks clamping elements for clamping the blade roots, and a turbomachine.

LIST OF REFERENCE NUMBERS

1

Blade assembly

2

axis of rotation

4

blade

6

blade

8th

front rotor disk

10

rear rotor disk

12

front clamping element

14

rear clamping element

16

airfoil

18

Inner shroud

20

sealing lip

22

sealing groove

24

shaft

26

end

28

side surface

30

front clamping surface

32

rear clamping surface

34

clamping surface

36

attack surface

38

annular recess

40

annular recess

42

ring recess

44

ring recess

46

axial elevation

48

web

50

Support head (investment head)

52

Printhead (investment head)

54

Support surface (contact surface)

56

Printing surface (contact surface)

58

axial elevation

60

ledger line

r

radius

x

axially

y

transversely

z

radial direction

Claims (11)

Blade assembly (1) for a turbomachine, with a plurality of individual blades (4) which are arranged side by side in the circumferential direction and which are clamped with their blade roots (6) between two rotor discs (8, 10), wherein on the rotor discs (8, 10) clamping elements (12, 14) for clamping the blade roots (6) attack. Blade assembly according to claim 1, wherein the clamping elements (12, 14) on the outside of the rotor discs (8, 10) engage and can be supported on a front rotor element and a rear rotor element. Blade assembly according to claim 1 or 2, wherein the blade roots (6) each have an end portion (26) thickened on both sides in the axial direction and the rotor discs (8, 10) each with a corresponding recess (38, 40) for receiving the end portion (26) in sections. are provided. A blade assembly according to claim 3, wherein the end portion (26) has two mutually opposite sinusoidal clamping surfaces (30, 32) and the recesses (38, 40) each have a sinusoidal inner contour. Blade assembly according to one of claims 1 to 4, wherein the clamping elements (12, 14) are integrally formed with the rotor discs (8, 10) and each having a web (48) with an end-side contact head (50), each having a contact surface (56 ) to bear against the rotor elements. Blade assembly according to one of claims 1 to 4, wherein the clamping elements (12, 14) are individual parts, each having a web (48) with two end and mutually opposite contact heads (50, 52), each having a contact surface (54, 56). for engagement with the rotor disks (8, 10) or rotor elements. Blade assembly according to claim 5 or 6, wherein the abutment surfaces (54, 56) each have an axial elevation (46, 58) and at least the rotor discs (8, 10) each with a corresponding axial recess (42, 44) for receiving the elevations (46, 58) are provided. Blade assembly according to claim 7, wherein the elevations (46, 58) each have a sinusoidal outer contour and the axial recesses (42, 44) each have a sinusoidal inner contour. A blade assembly according to any one of the preceding claims, wherein the end portions (26) and the tension members (12, 14) are disposed at an equal radius (r). Blade assembly according to one of the preceding claims, wherein between the blade root (6) and the rotor discs (8, 10), a heat protection element is arranged. Turbomachine with at least one blade assembly (1) according to one of the preceding claims, which is clamped between two rotor elements.

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