Blade for a turbomachine

Abstract

The invention refers to a blade for a turbomachine comprising a shroud which is positioned on a tip side of the blade having an outer surface having at least one circumferential web arranged thereon, at least one pocket recessed in the outer surface and a hardfacing provided on at least one edge of the shroud wherein a pocket recessed in the outer surface is arranged adjacent to the hardfacing and a side face of the pocket joins the supporting wall with a radius corresponding at least to the length of the shorter extension of the supporting wall and at most to 1.5 times the length of the larger extension of the supporting wall.

Claims

1. A blade for a turbomachine, comprising a shroud which is positioned on a tip side of the blade having an outer surface having at least one circumferential web arranged thereon, at least one pocket recessed in the outer surface and a hardfacing provided on at least one edge of the shroud wherein a first pocket is radially inwardly recessed in the outer surface and is arranged adjacent to the hardfacing wherein the pocket is open to the edge and wherein between the pocket and the hardfacing a supporting wall, having a shorter extension and a larger extension, is arranged for supporting the hardfacing during contact of the edge of the shroud with the edge of another shroud, wherein a side face of the pocket joins the supporting wall with a radius corresponding at least to the length of the shorter extension of the supporting wall and at most to 1.5 times the length of the a larger extension of the supporting wall.

2. The blade for a turbomachine according to claim 1, wherein the shroud further comprises a closed second pocket and an axially adjacent closed third pocket which are separated by a first reinforcement rib.

3. The blade for a turbomachine according to claim 2, wherein the second pocket and the first pocket being arranged circumferentially adjacent and separated by a second reinforcement rib.

4. The blade for a turbomachine according to claim 1, wherein the shroud further comprises an open fourth pocket being arranged circumferentially opposite to the first pocket.

5. The blade for a turbomachine according to claim 4, wherein the fourth pocket and the second pocket are arranged circumferentially adjacent and separated by a third reinforcement rib.

6. The blade for a turbomachine according to claim 1, wherein the shroud further comprises an open fifth pocket being arranged circumferentially adjacent to the third pocket and/or axially opposite to the first pocket and being separated from the fifth pocket by a fourth reinforcement rib.

7. The blade for a turbomachine according to claim 1, wherein the supporting wall has a substantially rectangular or rhomboid shape in top view of the shroud.

8. The blade for a turbomachine according to claim 7, wherein the shorter side of the supporting wall is arranged at the edge of the shroud.

9. The blade for a turbomachine according to claim 1, wherein the first pocket has substantially the same extension as the hardfacing with respect to the supporting wall.

10. The blade for a turbomachine according to claim 1, wherein the supporting wall extends at an angle with respect to a circumferential direction.

11. The blade for a turbomachine according to claim 1, wherein the first pocket extends from the supporting wall to the circumferential web.

12. The blade for a turbomachine according to claim 6, wherein the depth of at least one of the first pocket, second pocket, third pocket, fourth pocket and the fifth pocket, with regard to the outer surface, is in the range of 0.2 to 0.7 times the total thickness of the shroud in the area of the supporting wall.

13. The blade for a turbomachine according to claim 1, wherein the edges of the shroud have a substantially Z-shaped design.

14. The blade for a turbomachine according to claim 1, wherein the blade is configured and arranged in a turbomachine.

Description

BRIEF DESCRIPTION OF THE DRAWING FIGURES

(1) Further advantages, features and possible applications of the present invention will be described in the accompanying drawing figures in which:

(2) FIG. 1 is a schematic representation of an exemplary blade for a turbomachine having a shroud positioned on the tip side;

(3) FIG. 2 is a top view on the surface of the shroud of the exemplary blade shown in FIG. 1; and

(4) FIG. 3 is a detail of the top view of the shroud of FIG. 2.

DESCRIPTION OF THE INVENTION

(5) FIG. 1 shows a schematic representation of an exemplary blade 10 for a turbomachine having a shroud 12 positioned on the tip side of the blade 10. The shroud 12 comprises an outer surface 14 with two circumferential webs 16 arranged thereon. This design is also called “dogbone”-design allowing a high degree of reinforcement of the shroud 12 and the blade 10, respectively in both the circumferential direction and the axial direction. On the opposite side of the blade tip, where the shroud 12 is positioned, the blade root 18 is arranged. Between the blade root 10 and the shroud 12, the airfoil 17 of the blade 10 is arranged.

(6) FIG. 2 shows a top view on the shroud 12 of the exemplary blade 10 shown in FIG. 1. The shroud of the exemplary embodiment comprises several pockets 21, 22, 23, 24, 25 recessed in the outer surface 14 and two hardfacings 26, 27 provided at each edge 31, 32 of the shroud 12. A first pocket 22 recessed in the outer surface 14 is open to the edge 32 and is arranged adjacent to the hardfacing 26. Between the first pocket 22 and the hardfacing 26 a supporting wall 28 is arranged for supporting the hardfacing 28 during contact of the edge 32 of the shroud 12 with the edge of another shroud 11 (schematically indicated at the right hand sight). The shroud 12 of the blade 10 also comprises further pockets 21, 23, 24, 25 which are arranged at the outer surface 14 of the shroud 12 and the areas between two pockets 21, 22, 23, 24, 25 form reinforcement ribs 41, 42, 43, 44. As is also shown in FIG. 2, the edges 31, 32 of the exemplary embodiment of the shroud 12 have an essentially Z-shaped design.

(7) In particular, as illustrated in FIG. 2, the shroud 12 further comprises a closed second pocket 21 and an axially adjacent closed third pocket 24 which are separated by a first reinforcement rib 44. The second pocket 21 and the first pocket 22 are arranged circumferentially adjacent and separated by a second reinforcement rib 42.

(8) In the example of FIG. 2 the shroud 12 further comprises an open fourth pocket 25 which is arranged circumferentially opposite to the first pocket 22.

(9) The fourth pocket 25 and the second pocket 21 are arranged circumferentially adjacent and separated by a third reinforcement rib 41.

(10) In the example of FIG. 2 the shroud 12 further comprises an open fifth pocket 23 which is arranged circumferentially adjacent to the third pocket 24 and axially opposite to the first pocket 22 and which is separated from the fifth pocket 23 by a fourth reinforcement rib 43.

(11) FIG. 3 shows a detail of the top view of the shroud of FIG. 2. FIG. 3 shows the edge 32 of shroud 12 and the first pocket 22 in more detail. In the exemplary embodiment of the blade 10, the supporting wall 28 has a substantially rhomboid shape in top view of the shroud 12, wherein the shorter side of the supporting wall 28 is arranged at the edge 32 of the shroud 12. The first pocket 22 is recessed into the outer surface 14 of the shroud 12 and has substantially the same extension as the hardfacing 26 with respect to the supporting wall 28.

(12) In the exemplary embodiment, the supporting wall 28 extends at an angle α with respect to the circumferential direction C. As is shown in FIG. 3, the supporting wall 28 is arranged at an angle α of about 45° with regard to the circumferential direction. This design allows the supporting wall 28 to absorb forces F oriented in circumferential direction C and acting on the hardfacing 26 as in particular forces resulting from contacting a shroud 11 of another blade.

(13) The side face 22a of the first pocket 22 joins the supporting wall 28 with a radius R in particular corresponding at least to the length of the shorter extension 28a of the supporting wall 28 and at most to 1.5 times to the length of the larger extension 28b of the supporting wall 28. In the exemplary embodiment the radius R of the side face 22a of the first pocket 22 is about 1.2 times the extension 26a of the hardfacing 26 with respect to the supporting wall 28. The first pocket 22 of the exemplary embodiment shown in FIG. 3 extends from the supporting wall 28 to the circumferential web 16. The depth of the first pocket 22 with regard to the outer surface 14 is in the range of 0.2 to 0.7 times and in particular about 0.5 times the total thickness of the shroud 12 in the area of the supporting wall 28.

(14) It would be appreciated by those skilled in the art that various changes and modifications can be made to the illustrated embodiments without departing from the spirit of the present invention. All such modifications and changes are intended to be covered by the appended claims.