Blade-disk assembly, method and turbomachine

Abstract

A blade-disk assembly of a turbomachine is provided, the blade-disk assembly having a plurality of adjacent rotor blades and a closure blade which are tilted into an anchoring groove, and at least one circumferential retention element which interlockingly cooperates with at least one blade, as well as a plurality of tilt-out prevention elements which are disposed between the groove base and the root portions and which, in the rest state, space the blades from the groove base when in the upper position. The blade-disk assembly further has a locking element, a portion of which is located between the groove base and the root portions and which, in the rest state, spaces the closure blade from the groove base when in the upper position. A method for assembling such a blade-disk assembly, as well as a turbomachine, is also provided.

Claims

1. A blade-disk assembly of a turbomachine, the blade-disk assembly comprising: a plurality of adjacent rotor blades and a closure blade inserted with root portions in a circumferential anchoring groove of a rotor disk and cooperating with supporting portions of a forward wall and an aft wall of the circumferential anchoring groove in radially interlocking relationship therewith; at least one circumferential retention body having surfaces interlockingly cooperating with at least one of the closure blade and the adjacent rotor blades; and a plurality of tilt-out prevention elements disposed between a groove base and the root portions and, in a rest state, spacing the adjacent rotor blades from the groove base when in an upper position, wherein the tilt-out prevention elements are formed sheet-metal members supported, in the rest state, with supporting legs on the groove base; and a locking element which provides locking and tilt-out prevention, the locking element including a threaded shank and a head wider than the threaded shank, the locking element supported in an inclined internally threaded bore formed in the closure blade of the plurality of adjacent rotor blades and extending radially and at an inclined angle in a circumferential direction.

2. The blade-disk assembly as recited in claim 1 wherein the at least one circumferential retention body is an elongated body having ends inserted into two mutually aligned receiving recesses of the forward and aft walls, at least one of the adjacent rotor blades having an axial recess for receiving the circumferential retention element.

3. The blade-disk assembly as recited in claim 1 wherein at least one of the closure blade and the adjacent blades have an abutment portion, a respective tilt-out prevention element being in lateral contact with the abutment portion.

4. The blade-disk assembly as recited in claim 1, wherein a portion of locking element is located between the groove base and the root portions and, in the rest state, spacing the closure blade from the groove base when in the upper position.

5. The blade-disk assembly as recited in claim 4 wherein the locking element is provided between two adjacent tilt-out prevention elements.

6. A turbomachine comprising the blade-disk assembly as recited in claim 1.

7. A blade-disk assembly of a turbomachine, the blade-disk assembly comprising: a plurality of adjacent rotor blades and a closure blade inserted with root portions in a circumferential anchoring groove of a rotor disk and cooperating with supporting portions of a forward wall and an aft wall of the circumferential anchoring groove in radially interlocking relationship therewith; at least one circumferential retention element interlockingly cooperating with at least one of the closure blade and the adjacent rotor blades, wherein the at least one circumferential retention element is a wall portion of one of the forward and aft walls, and at least one of the closure blade and the adjacent blades has a corresponding axial setback in a platform to cooperate with the wall portion; and a plurality of tilt-out prevention elements disposed between a groove base and the root portions and, in a rest state, spacing the adjacent rotor blades from the groove base when in an upper position, wherein the tilt-out prevention elements are formed sheet-metal members supported, in the rest state, with supporting legs on the groove base; and a locking element which provides locking and tilt-out prevention, the locking element including a threaded shank and a head wider than the threaded shank, the locking element supported in an inclined internally threaded bore formed in the closure blade of the plurality of adjacent rotor blades and extending radially and at an inclined angle in a circumferential direction.

8. A blade-disk assembly of a turbomachine, the blade-disk assembly comprising: a plurality of adjacent rotor blades and a closure blade inserted with root portions in a circumferential anchoring groove of a rotor disk and cooperating with supporting portions of a forward wall and an aft wall of the circumferential anchoring groove in radially interlocking relationship therewith; at least one circumferential retention body having surfaces interlockingly cooperating with at least one of the closure blade and the adjacent rotor blades; and a plurality of tilt-out prevention elements disposed between a groove base and the root portions and, in a rest state, spacing the adjacent rotor blades from the groove base when in an upper position, wherein the tilt-out prevention elements are formed sheet-metal members supported, in the rest state, with supporting legs on the groove base; a locking element having one or more contact surfaces engaging the closure blade, a portion of locking element being located between the groove base and the root portions and, in the rest state, spacing the closure blade from the groove base when in the upper position; wherein the locking element has a main body and a plastically deformable tab engaging in a cutout of the closure blade.

9. The blade-disk assembly as recited in claim 8 wherein the main body has a plurality of tool receptacles arranged adjacent one another in a circumferential direction of the blade-disk assembly.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Preferred exemplary embodiments of the present invention are described in more detail below with reference to schematic drawings, in which:

(2) FIG. 1 is a longitudinal sectional view through a first exemplary embodiment of a blade-disk assembly according to the present invention;

(3) FIG. 2 is a frontal cross-sectional view through the first exemplary embodiment;

(4) FIG. 3 is a bottom view of a rotor blade and a tilt-out prevention element according to the first exemplary embodiment;

(5) FIG. 4 is a top view of an installed circumferential retention element according to the first exemplary embodiment;

(6) FIG. 5 is a view showing the circumferential retention element in cooperation with a rotor blade;

(7) FIG. 6 is a front view of a root portion of a closure blade according to the first exemplary embodiment;

(8) FIG. 7 is a perspective view of the root portion of the closure blade;

(9) FIG. 8 is a longitudinal sectional view through a second exemplary embodiment of the blade-disk assembly according to the present invention;

(10) FIG. 9 is an isolated view of a locking element according to the second exemplary embodiment;

(11) FIG. 10 is a view showing the locking element of the second exemplary embodiment in cooperation with a closure blade;

(12) FIG. 11 is a sectional view showing the locking element of the second exemplary embodiment in cooperation with a closure blade, as well as two adjacent rotor blades as seen from the rear;

(13) FIG. 12 is a longitudinal sectional view through a third exemplary embodiment of the blade-disk assembly according to the present invention.

DETAILED DESCRIPTION

(14) As shown in FIGS. 1 and 2 in longitudinal section, a first exemplary embodiment of an inventive blade-disk assembly of a turbomachine has a row of blades 2 and a rotor disk 4. Referring to FIG. 1, the turbomachine is traversed by a hot gas from left to right in the direction of its longitudinal axis; i.e., in the axial direction. Referring to FIG. 2, the hot gas enters perpendicularly into the plane of the drawing. The turbomachine is, for example, a gas turbine, and especially an aircraft engine.

(15) Blade-disk assembly 1 forms part of a rotor that rotates about the longitudinal machine axis. In the exemplary embodiment shown, the rotor is a turbine rotor, but may also be a compressor rotor. Blade row 2 is composed of a plurality of rotor blades 6, 8, 10, 11 arranged adjacent one another in the circumferential direction of blade-disk assembly 1. Rotor blades 6, 8, 10, 11 are each received with their root or root portion 12 and their neck or neck portion 14 in a circumferential anchoring groove 16 of rotor disk 4.

(16) Anchoring groove 16 has a forward wall 18 and an aft wall 20, as viewed in the direction of flow, the forward and aft walls being connected by a groove base 22. In order to retain rotor blades 6, 8, 10, 11 radially, walls 18, 20 have two annular bulges or supporting portions 24, 26 located opposite each other. During operation of the turbomachine, the roots 12 of rotor blades 6, 8, 10, 11, which are wider than their necks 14, are in radial contact with the supporting portions. In the exemplary embodiment shown, groove base 22 is not inclined with respect to the axial direction.

(17) Rotor blades 6, 8, 10, 11 each extend with a forward platform portion 28 over forward wall 18 and terminate flush with a radially extending end face 30 of forward wall 18. In the rest state, rotor blades 6, 8, 10, 11 each rest with their forward platform portion 28 on a circumferential surface 32 of forward wall 18, and, during operation, are spaced therefrom by a small radial gap. Since forward wall 18 is formed with a uniform height in the circumferential direction, all rotor blades 6, 8, 10, 11 have an identical platform portion 28.

(18) Rotor blades 6, 8, 10, 11 extend with a downstream or aft platform portion 36 over aft wall 20. Because aft wall 20 has a smaller height than forward wall 18, aft platform portions 36 of rotor blades 6, 8, 10, 11 are each radially spaced from aft wall 20 when at rest. In order to prevent rotor blades 6, 8, 10 from inadvertently falling out when at rest in the upper position, tilt-out prevention elements 38 are disposed between groove base 22 and roots 12 of rotor blades 6, 8, 10.

(19) The rotor blade designated by reference numeral 11 is a so-called closure blade, which is inserted last into anchoring groove 16 and which closes the row of blades 2. The closure blade does not cooperate with a tilt-out prevention element 38, but has an alternative tilt-out prevention mechanism, which will be described hereinafter.

(20) In the rest state, rotor blades 6, 8, 10 are spaced by tilt-out prevention elements 38 from groove base 22 in the upper position shown, and are thus raised toward supporting portions 24, 26. Consequently, rotor blades 6, 8, 10 are positioned with their roots 12 located near supporting portions 24, 26 and spaced apart from groove base 22, so that they cannot tilt or be tilted out from anchoring groove 16.

(21) As illustrated in FIG. 1, tilt-out prevention elements 38 have a profile including a forward supporting leg 40, an aft supporting leg 42, and a seat portion 44 extending between supporting legs 40, 42. Tilt-out prevention elements 38 take the form of, for example, multiply bent sheet-metal members and have resilient properties, In the installed state, tilt-out prevention elements 38 are supported with their supporting legs 40, 42 on groove base 22 when in the upper position. Rotor blades 6, 8, 10 rest with the undersides 46 of their roots on seat portions 44, whereby the upper surfaces 48, 50 of their roots are brought nearly into contact with supporting portions 24, 26. When the turbomachine is at rest, rotor blades 6, 8, 10 are able to perform slight radial movements. The shape of seat portions 44 is selected to correspond to the roots' undersides 46. Since the surface segments of seat portion 44 are angled toward each other, tilt-out prevention elements 38 are here in particular in the form of M-shaped sections. If the roots' undersides 46 are, for example, flat, then tilt-out prevention elements 38 are U-shaped in section (see third exemplary embodiment in FIG. 12).

(22) As shown in FIG. 2, each of rotor blades 6, 8, 10 may have one tilt-out prevention element 38 associated therewith. Alternatively, one tilt-out prevention element 38 is associated with several rotor blades 6, 8, 10. In order to circumferentially retain tilt-out prevention elements 38 in anchoring groove 16, rotor blades 6, 8, 10 and closure blade 11 each have an axially extending abutment portion 52. Abutment portion 52 provides a lateral shoulder surface for tilt-out prevention elements 38, so that in the assembled state, as shown in FIG. 2, tilt-out prevention elements 38 are in contact at both sides with respective adjacent abutment portions 52, 54.

(23) As shown in FIGS. 2, 4, 5, blade-disk assembly 1 has at least one circumferential retention element 56 for circumferentially retaining rotor blades 6, 8, 10 and closure blade 11. Circumferential retention element 56 is, for example, a rectangular body having a flat lower contact surface 57 and a rounded head surface 58. It forms an interlocking connection with at least one of rotor blades 6, 8, 10 which has a recess 59 extending in the longitudinal direction and having a convex inner surface corresponding to the outer contour of circumferential retention element 56 for receiving the same. It is, of course, also possible to provide several circumferential retention elements 56. For example, each of rotor blades 6, 8, 10 may have one circumferential retention element 56 associated therewith.

(24) Circumferential retention element 56 is inserted at its ends into two mutually aligned receiving recesses 60 in the walls and, in the assembled state, rests with its lower contact surface 57 on a tilt-out prevention element 38. Here, receiving recesses are axial setbacks in the opposing supporting portions 24, 26. Preferably, receiving recesses 60 are formed in the region of supporting portions 24, 26 and extend radially therethrough, so that, on the one hand, walls 18, 20 are not weakened and, on the other hand, circumferential retention element 56 can be inserted in a direction from radially outward to radially inward.

(25) As shown in FIGS. 1, 2, 6 and 7, closure blade 11 cooperates with a locking element 62 to lock blade row 2 in place, the locking element at the same time acting as a tilt-out prevention mechanism, protecting closure blade 11 from tilting out when in the upper position shown. Locking element 62 takes the form of a threaded element having a threaded shank 64 and a head 66 wider than threaded shank 64, and is supported in an internally threaded bore 68 formed in closure blade 11 and extending through the platform, neck 14, and root 12 thereof in a radial direction. In order to prevent closure element 62 from colliding with the closure blade's airfoil 69, internally threaded bore 68 is inclined in a circumferential direction. Head 66 of locking element 62 projects from the root of closure blade 11 and enters between two adjacent tilt-out prevention elements 38. In order to simplify insertion of closure blade 11 into anchoring groove 16, the closure blade has a recess 70 formed in its root to receive head 66, or at least a portion thereof, during insertion. For purposes of operating locking element 62, the locking element has an outer tool receptacle 72 which, in the exemplary embodiment shown, takes the form of a hexagonal socket. In order avoid flow turbulences in the region of locking element 62, locking element 62; i.e., threaded shank 64, is countersunk with respect to a platform upper surface 74 when in the locking position. In order to fix locking element 62 in its locking position, an anti-rotation feature (not shown) is provided which prevents unintentional rotation, and thus displacement, of locking element 62.

(26) To assemble the first exemplary embodiment of the blade-disk assembly, first, the at least one circumferential retention element 56 is radially inserted into receiving recesses 60 and thereby mounted in rotor disk 4. Then, rotor blade 6 is tilted into anchoring groove 16 over circumferential retention element 56. The tilting into place is carried out over aft wall 20 in a forward axial direction. In the process, root 12 of rotor blade 6 is caused to enter under aft supporting portion 26, whereupon the blade is tilted forward, thereby engaging it with the circumferential retention element 56 resting on groove base 22 in such a way that circumferential retention element 56 at least partially enters recess 59. Subsequently, at least one tilt-out prevention element 38 is inserted into anchoring groove 16 and slid circumferentially under circumferential retention element 56, and thus under rotor blade 6. Like rotor blade 6, circumferential retention element 56 now rests on tilt-out prevention element 38 and is spaced from groove base 22. Then, remaining rotor blades 8, 10 are tilted into anchoring groove 16 and spaced from groove base 22 by subsequently inserted tilt-out prevention elements 38. Of course, rotor blades 6, 8, 10 may also be raised in groups; i.e., one tilt-out prevention element 38 may be slid under several rotor blades 6, 8, 10 at the same time. Finally, closure blade 11 is tilted into place with locking element 62 in the retracted position. In the retracted position, head 66 of locking element 62 is at least partially located within recess 70. Locking element 62 is extended to its locking position by rotational movement, thereby causing its head 66 to rest against groove base 22 between the adjacent tilt-out prevention elements 38 and thereby raise closure blade 11. The locking position is reached once closure blade 11 is protected from tilting out when at rest. Preferably, locking element 62 is extended only to such an extent that its head 66 is spaced from groove base 22 during operation. Accordingly, closure blade 11 is not clamped by locking element 62 between groove base 2 and supporting portions 24, 26. In the rest state, slight radial movements are possible. This allows closure blade 11 to assume an optimal operation position and also prevents abrasion of material between head 66 and groove base 22.

(27) FIGS. 8, 9, 10 and 11 show a second exemplary embodiment of the blade-disk assembly 1 according to the present invention. The second exemplary embodiment illustrated in FIGS. 8 through 11 differs from the first exemplary embodiment of FIGS. 1 through 7 essentially in that it has an alternative locking element 62 and an alternative closure blade 11 cooperating with this locking element 62.

(28) Locking element 62 has a main body which is similar to a tilt-out prevention tilting element. Thus, it has a profile substantially similar to that of the aforedescribed tilt-out prevention elements 38, which are also used in this exemplary embodiment. Locking element 62 is preferably a multiply bent sheet-metal member having resilient properties, which is M-shaped here because the surface segments of the undersides 46 of the root of closure blade 11 and of the roots of the rotor blades 8, 10 adjacent to at least closure blade 11 are, in each instance, angled toward each other. Locking element 62 has a forward supporting leg 76 and an aft supporting leg 78, as well as a seat portion 80 connecting supporting legs 76, 78 and shaped correspondingly to the roots' undersides 46. Locking element 62 has a width or circumferential extent approximately twice the root width of rotor blades 8, 10 and closure blade 11. Rotor blades 8, 10 and closure blade 11 have the same root width. Thus, when in the upper position shown, closure blade 11 is completely raised by locking element 62. The adjacent rotor blades 8, 10 each rest with one half on locking element 62.

(29) For purposes of cooperating with closure blade 11, locking element 62 has a centrally disposed tab 82 which is moved from an unlocking position a to a locking position b through plastic deformation. Tab 82 is an integral portion of seat portion 80 and, when in unlocking position a, is disposed within an opening 84. Thus, when in unlocking position a, tab 82 is flush with seat portion 80, which simplifies the mounting of closure blade 11 and adjacent rotor blades 8, 10. In particular, tab 82 is configured to follow the shape of seat portion 80.

(30) In order to receive tab 82, closure blade 11 has a correspondingly shaped locking cutout 86 formed in its root. Locking cutout 86 is formed in root 12 on the aft side thereof at a central position, as viewed in the lateral direction; i.e., in the circumferential direction in the assembled state, and extends through the root's underside 46 and the root's aft upper surface 50. Locking cutout 86 has a locking surface 88 which is inclined with respect to the axial direction and provides a stop for the folded-up tab 82 and, thus, defines locking position b. The width of locking cutout 86 corresponds approximately to width of tab 82; or rather, locking cutout 86 is slightly wider than tab 82 to facilitate assembly.

(31) In order to adjust the position of locking element 62 during assembly, main body 64 has a plurality of tool receptacles 90, 92 formed therein which are arranged adjacent to each other in the circumferential direction. For the sake of clarity, only two tool receptacles are provided with reference numerals 90, 92. Tool receptacles 90, 92 are configured identically and serve for engagement of a suitable tool. They enable locking element 62, when inserted in anchoring groove 16, to be displaced even after rotor blades 8, 10 have been inserted.

(32) The difference from the aforedescribed method for assembling blade-disk assembly 1 resides only in the manner in which closure blade 11 and the rotor blades 8, 10 flanking it are mounted. After previous rotor blades 6 have been inserted together with at least one circumferential retention element 56 and the tilt-out prevention elements 38 supporting them when in the upper position, and once they are in their nominal positions, first, locking element 62 is inserted into anchoring groove 16 and moved laterally. Subsequently, rotor blades 8, 10 and closure blade 11 are tilted in at the free position of anchoring groove 16 by a movement in an aft-to-fore direction and moved to their respective nominal positions. Then, locking element 62 is accurately adjusted in position, and closure blade 11 is titled in. Subsequently, tab 82 is bent from its unlocking position a toward its locking position b until it enters locking cutout 86 and is in contact with locking surface 88. Now, when at rest in the upper position shown, rotor blades 8, 10 and closure blade 11 rest on locking element 62 and are protected from tilting out. In this condition, closure blade 11 rests on locking element 62 over the entire area. Rotor blades 8, 10 each rest with one half on locking element 62. Thus, rotor blades 8, 10 and closure blade 11 are spaced from groove base 22 and positioned with the upper surfaces 44, 46 of their roots located near supporting portions 24, 26. The engagement of the tab in locking cutout 86 prevents, in particular, tilting-out of closure blade 11.

(33) FIG. 12 shows a longitudinal sectional view through a third exemplary embodiment of the blade-disk assembly 1 according to the present invention. The third exemplary embodiment illustrated in FIG. 12 differs from the preceding exemplary embodiments essentially in that it has an alternative circumferential retention feature.

(34) A closure blade 11 is configured similarly to the closure blade according to the first exemplary embodiment. Accordingly, closure blade 11 cooperates with a screw-like locking element 62 which is supported in an internally threaded bore 68 and has a head 66 of greater width with which it enters between two tilt-out prevention elements 38 in the assembled state. When at rest in the upper position, head 66 rests on groove base 22 and thereby raises closure blade 11. In the operating state shown here, closure blade 11 is pressed with its root 12 against supporting portions 24, 26, and head 66 of locking element 62 is spaced from groove base 22.

(35) In order to raise the other rotor blades when at rest in the upper position, suitable tilt-out prevention elements 38 are provided which are configured similarly to the tilt-out prevention elements 38 according to the preceding exemplary embodiments. They each have two supporting legs 40, 42 and a seat portion 44 connecting supporting legs 40, 42. The essential difference of the tilt-out prevention elements 38 used here is in that seat portion 44 is flat and aft supporting leg 42 is longer than forward supporting leg 40. Thus, tilt-out prevention elements 38 are U-shaped in section. The greater length of second supporting leg 42 results from the inclination of groove base 22 with respect to the axial direction. As considered in the direction of flow, groove base 22 is inclined in a direction from radially outward to radially inward. The difference in length between supporting legs 40, 42 compensates for this difference in height or radial offset, so that seat portion 44 is not inclined with respect to the axial direction.

(36) According to FIG. 12, the alternative circumferential retention feature is provided in that the forward platform portion 28 of at least one rotor blade, here closure blade 11, is laterally in contact with a circumferential retention element 56 configured as a portion of forward wall 18. Circumferential retention element 56 is provided by a radial cutout 94 in forward wall 18. For engagement on circumferential retention element 56, forward platform portion 28 of closure blade 11 has an axial setback 96 formed in the region of its forward edge, at least in a corner region.

(37) Forward wall 18 may have a plurality of such circumferential retention elements 56, so that forward wall 18 would be configured in a crown-like manner. In such an alternative, the other rotor blades 8, 10, 12 would accordingly have a corresponding forward platform portion 28.

(38) The essential difference from the method of the first exemplary embodiment is that no circumferential retention elements 56 need to be inserted into anchoring groove 16 during assembly, since circumferential retention elements 56 are formed directly on forward wall 20.

(39) Disclosed is a blade-disk assembly of a turbomachine, the blade-disk assembly having a plurality of adjacent rotor blades and a closure blade which are tilted into an anchoring groove, and at least one circumferential retention element which interlockingly cooperates with at least one blade, as well as a plurality of tilt-out prevention elements which are disposed between the groove base and the root portions and which, in the rest state, space the blades from the groove base when in the upper position. The blade-disk assembly further has a locking element, a portion of which is located between the groove base and the root portions and which, in the rest state, spaces the closure blade from the groove base when in the upper position. Also disclosed is a method for assembling such a blade-disk assembly, as well as a turbomachine.

LIST OF REFERENCE NUMERALS

(40) 1 blade-disk assembly 2 blade row 4 rotor disk 6 rotor blade 8 rotor blade 10 rotor blade 11 rotor blade/closure blade 12 root/root portion 14 neck/neck portion 16 anchoring groove 18 forward wall 20 aft wall 22 groove base 24 supporting portion 26 supporting portion 28 forward platform portion 30 radially extending end face 32 circumferential surface 36 aft platform portion 38 tilt-out prevention element 40 supporting leg 42 supporting leg 44 seat portion 46 underside of the root 48 forward upper surface of the root 50 aft upper surface of the root 52 axial abutment portion 54 axial abutment portion 56 circumferential retention element 57 lower contact surface 58 head surface 59 axial recess 60 receiving recess 62 locking element 64 threaded shank 66 head 68 internally threaded bore 69 airfoil 70 recess 72 tool receptacle 74 platform upper surface 76 supporting leg 78 supporting leg 80 seat portion 82 tab 84 opening 86 locking cutout 88 locking surface 90 tool receptacle 92 tool receptacle 94 radial cutout 96 axial setback a unlocking position b locking position