Gas turbinen rotor blade

Abstract

A turbine or compressor stage of a gas turbine, the rotor blade having a radially outer shroud (1) which has a sealing fin array having a first sealing fin (3.1) and a second sealing fin (3.2) which is adjacent to the first sealing fin and connected thereto by a first groove base (10) having a circumferential region (13) of maximum radial height, which is located at a first circumferential position is provided. The sealing fin array has a third sealing fin (3.3) adjacent to the second sealing fin and opposite to the first sealing fin, the third sealing fin being connected to the second sealing fin by a second groove base (20) having a circumferential region (23) of maximum radial height, which is located at a second circumferential position different from the first circumferential position.

Claims

1. A rotor blade for a turbine or compressor stage of a gas turbine, the rotor blade comprising: a radially outer shroud having a sealing fin array having a first sealing fin and a second sealing fin adjacent to the first sealing fin and connected to the first sealing fin by a first groove base having a circumferential region of maximum radial height and located at a first circumferential position, the sealing fin array having a third sealing fin adjacent to the second sealing fin and opposite to the first sealing fin, the third sealing fin being connected to the second sealing fin by a second groove base having a further circumferential region of maximum radial height located at a second circumferential position different from the first circumferential position.

2. The rotor blade as recited in claim 1 wherein the sealing fin array has at least one further sealing fin connected to an adjacent one of the first, second and third sealing fins by a further groove base having a third circumferential region of maximum radial height located at a further circumferential position different from the first or second circumferential positions.

3. The rotor blade as recited in claim 1 wherein a circumferential position the groove base is further away from the leading edge than the second groove base, the offset being in a direction from a trailing edge toward a leading edge of the rotor blade.

4. The rotor blade as recited in claim 1 wherein the circumferential region and the further circumferential region lie on a straight line.

5. The rotor blade as recited in claim 1 wherein the groove base of the sealing fin array has a first flank sloping upwardly in the circumferential direction, to the circumferential region of maximum radial height, and, oriented oppositely to the first flank, a second flank slopes downwardly in the circumferential direction from the circumferential region of maximum radial height.

6. The rotor blade as recited in claim 5 wherein the first flank slopes monotonically upwardly and the second flank monotonically downwardly toward a second edge of the shroud located opposite to a first edge in the circumferential direction.

7. The rotor blade as recited in claim 5 wherein the first and second flanks merge into each other at an edge or into a plateau at two edges.

8. The rotor blade as recited in claim 1 wherein the groove base of the sealing fin array is at least partly contoured by machining with a geometrically undefined cutting edge or by primary shaping.

9. The rotor blade as recited in claim 8 wherein the groove base is contoured by machining with the geometrically undefined cutting edge, the machining including grinding, thermal or electrochemical machining, or electrical discharge machining.

10. The rotor blade as recited in claim 8 wherein the groove base is primary-shaped, the primary shaping including casting.

11. A gas turbine comprising: at least one turbine or compressor stage having at least one rotor blade as recited in claim 1.

12. An aircraft engine gas turbine comprising: at least one turbine or compressor stage having at least one rotor blade as recited in claim 1.

13. A method for manufacturing a rotor blade as recited in claim 1, the method comprising: contouring at least one groove base of the sealing fin array by machining with a geometrically undefined cutting edge or by primary shaping.

14. The method as recited in claim 13 wherein the groove base is contoured by machining with the geometrically undefined cutting edge, the machining including grinding, thermal or electrochemical machining, or electrical discharge machining.

15. The method as recited in claim 13 wherein the groove base is primary-shaped, the primary shaping including casting.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Further advantageous refinements of the present invention will be apparent from the dependent claims and the following description of preferred embodiments. To this end, the drawings show, partly in schematic form, in:

(2) FIG. 1A: a top view looking radially at a shroud of a rotor blade of a gas turbine, according to an embodiment of the present invention;

(3) FIGS. 1B-1D: cross-sectional views taken along lines B-B (FIG. 1B), C-C (FIG. 1C) and D-D (FIG. 1D) in FIG. 1A; and

(4) FIGS. 2B-2D: cross-sectional views taken along lines B-B (FIG. 2B), C-C (FIG. 2C) and D-D (FIG. 2D) in FIG. 1A for an alternative embodiment of the present invention.

DETAILED DESCRIPTION

(5) FIG. 1A shows a top view looking radially inwardly at a shroud 1 of a rotor blade of a turbine stage of an aircraft engine gas turbine, according to an embodiment of the present invention. FIGS. 1B through 1D show cross-sectional views taken along lines B-B (FIG. 1B), C-C (FIG. 1C) and D-D (FIG. 1D) in FIG. 1A.

(6) The radially outer shroud is formed integrally with an airfoil 2 of the rotor blade, a portion of which is shown in FIGS. 1B through 1D. The shroud has two z-shaped edges (at the top and bottom in FIG. 1) which are opposite to each other in the circumferential direction.

(7) On its radially outer curved surface facing away from the airfoil (at the right in FIGS. 1B through 1D), the shroud has a sealing fin array including a first sealing fin 3.1 located at an upstream-most position; i.e., closest to the leading edge (at the left in FIG. 1A), a second sealing fin 3.2 adjacent thereto, and a third sealing fin 3.3 adjacent to the second sealing fin and opposite to the first sealing fin, and a further sealing fin 3.4 which is adjacent to the third sealing fin and opposite to the second sealing fin and located at a downstream-most position; i.e., closest to the trailing edge (at the right in FIG. 1A). The sealing fins extend in the circumferential direction (vertically in FIG. 1).

(8) The first and second sealing fins are connected by a first groove base 10; the second and third sealing fins are connected by a second groove base 20; the third and the further sealing fins are connected by a further groove base 30.

(9) The groove bases each have a first flank 11, 21, or 31, respectively, and, oriented oppositely thereto, a second flank 12, 22 or 32, respectively. The first flank slopes linearly upwardly in the circumferential direction (from top to bottom in FIGS. 1B through 1D) from a first edge of the shroud (at the top in FIG. 1) to an edge 13, 23, or 33, respectively, at which it merges into the second flank, which slopes linearly downwardly in an opposite direction toward a second edge of the shroud located opposite to the first edge in the circumferential direction (at the bottom in FIG. 1). Thus, these edges 13, 23, 33 each constitute a circumferential region of maximum radial height of the respective groove base 10, 20 or 30.

(10) These edges, or regions of maximum radial height, 13, 23 and 33 of the first, second and further groove bases are circumferentially offset from one another, as is apparent, in particular, when viewing the cross-sectional views 1B, 1C and 1D together.

(11) The second circumferential position of circumferential region 23 of the second groove base is circumferentially offset from the first circumferential position of circumferential region 13 of the first groove base, which is closest to the leading edge, the offset being in a direction from a trailing edge toward a leading edge of the rotor blade (from top to bottom in FIG. 1), as is apparent, in particular, when viewing the cross-sectional views 1B and 1C together.

(12) The further circumferential position of further circumferential region 33 of groove base 30, which is furthest away from the leading edge, is circumferentially offset in the same manner from the second circumferential position of circumferential region 23 of the second groove base, as is apparent, in particular, when viewing the cross-sectional views 1C and 1D together. Thus, the circumferential regions of maximum height 13, 23 and 33 of the three adjacent groove bases 10, 20 and 30 lie on a straight line.

(13) As a result, a stiffening rib V is created on groove bases 10, 20 and 30, the stiffening rib diagonally intersecting the fins 3.2, 3.3 disposed therebetween. This stiffening rib may be easily produced by grinding each of the groove bases in opposite directions and in circumferentially offset relationship to each other.

(14) FIGS. 2B through 2D are cross-sectional views corresponding to FIGS. 1B through 1D, illustrating a rotor blade according to an alternative embodiment of the present invention, which, in a top view looking radially inwardly thereat, corresponds to FIG. 1A. Corresponding elements are identified by the same reference numerals, so that reference is made to the above description and only the differences will be discussed below.

(15) In the embodiment of FIG. 2, the first and second flanks 11, 12; 21, 22 and 31, 32, respectively, merge, at a two edges, into respective plateaus 13, 23 and 33 of constant, maximum radial height, each of which consequently constitutes the circumferential region of maximum radial height in accordance with the present invention. The circumferential position of each such plateau may be the circumferential position of the edge that is closer to the leading edge (the lower one in FIG. 2), the circumferential position of the edge that is further away from the leading edge (the upper one in FIG. 2), or the center between the two edges.

(16) Again, the second circumferential position of circumferential region 23 of the second groove base is circumferentially offset from the first circumferential position of circumferential region 13 of the first groove base, which is closest to the leading edge, the offset being in a direction from a trailing edge toward a leading edge of the rotor blade (from top to bottom in FIG. 2), as is apparent, in particular, when viewing the cross-sectional views 2B and 2C together. The further circumferential position of further circumferential region 33 of groove base 30, which is furthest away from the leading edge, is circumferentially offset in the same manner from the second circumferential position of circumferential region 23 of the second groove base, as is apparent, in particular, when viewing the cross-sectional views 2C and 2D together. Thus, again, the circumferential regions of maximum height 13, 23 and 33 of the three adjacent groove bases 10, 20 and 30 lie on a straight line.

(17) Again, as a result, a stiffening rib is created on groove bases 10, 20 and 30, the stiffening rib diagonally intersecting the fins 3.2, 3.3 disposed therebetween. This stiffening rib may be produced, for example, by electrical discharge machining, electrochemical machining or by casting. However, while the diagonal stiffening rib of the embodiment of FIG. 1 is configured in the manner of a roof ridge, the stiffening rib of the embodiment of FIG. 2 has a plateau.

(18) Although the above is a description of exemplary embodiments, it should be noted that many modifications are possible. It should also be appreciated that the exemplary embodiments are only examples, and are not intended to limit the scope, applicability, or configuration in any way. Rather, the foregoing detailed description provides those skilled in the art with a convenient road map for implementing at least one exemplary embodiment, it being understood that various changes may be made in the function and arrangement of elements described without departing from the scope of protection set forth in the appended claims and their equivalent combinations of features.

LIST OF REFERENCE NUMERALS

(19) 1 shroud 2 airfoil 3.1 first fin 3.2 second fin 3.3 third fin 3.4 further fin 10 first groove base 20 second groove base 30 further groove base 11; 21; 31 first flank 12; 22; 32 second flank 13; 23; 33 edge/plateau (circumferential region of maximum radial height) V stiffening rib