Rotor for a turbomachine

Abstract

A rotor (100) for a turbomachine is provided, having at least two bladed, detachably interconnected rotor stages (1, 3, 6), a flange (17) of a first rotor stage (1) being attached to a rotor disk (25) of a second, adjacent rotor stage (3) via at least one fastening element (7). The rotor disk (25) has a through bore (11) for connecting the two rotor stages (1, 3) by the fastening element (7); the through bore (11) having a cross section that is larger in the circumferential direction (u) of the rotor disk (25) than in the radial direction (r) thereof.

Claims

1. A rotor for a turbomachine, the rotor comprising: at least two bladed, detachably interconnected rotor stages including a first rotor stage and an adjacent second rotor stage, a flange of the first rotor stage being attached to a rotor disk of the second rotor stage via at least one fastener element, the rotor disk having a through bore for connecting the first and second rotor stages by the fastener element, the through bore having a cross section larger in a circumferential direction of the rotor disk than in a radial direction of the rotor disk; wherein the cross-sectional dimensions of the through bore in the circumferential direction of the rotor disk are at most 20% larger than the cross-sectional dimensions of the through bore in the radial direction of the rotor disk.

2. The rotor as recited in claim 1 wherein the through bore has an elliptical cross section, the elliptical cross section having a major axis larger in the circumferential direction of the rotor disk than a minor axis in the radial direction of the rotor disk.

3. The rotor as recited in claim 1 wherein the through bore has an elongated hole shape.

4. The rotor as recited in claim 1 wherein the through bore is configured at a radially outer end region of the rotor disk at a transition to a rotor main body.

5. The rotor as recited in claim 1 wherein the flange of the first rotor stage is located at the axially downstream end of a rotor arm of the first rotor stage relative to a through flow direction of the turbomachine.

6. The rotor as recited in claim 1 wherein the at least two rotor stages include a third rotor stage, a third rotor stage flange being configured at an axial upstream end of a rotor arm of the third rotor stage relative to a through flow direction of the turbomachine.

7. The rotor as recited in in claim 1 wherein the first rotor stage is a first upstream rotor stage of the rotor.

8. The rotor as recited in claim 6 wherein the fastener element is attached to the third rotor stage flange.

9. The rotor as recited in claim 1 wherein in the circumferential direction of the rotor disk, a major axis of an elliptical cross section is at most 20% larger than a minor axis in the radial direction of the rotor disk.

10. The rotor as recited in claim 1 wherein the cross-sectional dimensions of the through bore in the circumferential direction of the rotor disk are at most 15% larger than the cross-sectional dimensions of the through bore in the radial direction of the rotor disk; or, in the circumferential direction of the rotor disk, a major axis of an elliptical cross section is at most 15% larger than a minor axis in the radial direction of the rotor disk.

11. The rotor as recited in claim 1 wherein the cross-sectional dimensions of the through bore in the circumferential direction of the rotor disk are at most 10% larger than the cross-sectional dimensions of the through bore in the radial direction of the rotor disk; or, in the circumferential direction of the rotor disk, a major axis of an elliptical cross section is at most 10% larger than a minor axis in the radial direction of the rotor disk.

12. The rotor as recited in claim 1 wherein the cross-sectional dimensions of the through bore in the circumferential direction of the rotor disk are at most 5% larger than the cross-sectional dimensions of the through bore in the radial direction of the rotor disk; or, in the circumferential direction of the rotor disk, a major axis of an elliptical cross section is at most 5% larger than a minor axis in the radial direction of the rotor disk.

13. The rotor as recited in claim 2 wherein the minor axis of the elliptical cross section of the through bore is at most 10% larger than a diameter of a shank of the fastener element in the through bore.

14. The rotor as recited in claim 2 wherein the minor axis of the elliptical cross section of the through bore is at most 5% larger than a diameter of a shank of the fastener element in the through bore.

15. The rotor as recited in claim 1 wherein the fastener element includes a bolt having a bolt head and includes a retainer element.

16. The rotor as recited in claim 15 wherein a shank of the bolt has a thread, and the retainer element being a nut.

17. The rotor as recited in claim 1 wherein a surface of the through bore has an arithmetical mean roughness value of at most 0.4 m.

18. The rotor as recited in claim 1 wherein a surface of the through bore has an arithmetical mean roughness value of at most 0.2 m.

19. An axial gas turbine stage comprising the rotor as recited in claim 1.

20. A low-pressure turbine comprising the axial gas turbine stage as recited in claim 19.

21. An axial gas turbine comprising the turbomachine, the turbomachine including the rotor as recited in claim 1.

22. An aircraft engine comprising the axial gas turbine as recited in claim 21.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The present invention is explained exemplarily in the following with reference to the accompanying drawings, in which identical reference numerals denote like or similar components. It holds in the highly schematically, simplified figures that:

(2) FIG. 1 shows a rotor according to the present invention having three rotor stages that are interconnected by a bolt; and

(3) FIG. 2 shows a view of a portion of a rotor disk of an inventive rotor having a through bore that has an elliptical cross section.

DETAILED DESCRIPTION

(4) FIG. 1 shows an inventive rotor 100 for an axial turbomachine having three rotor stages 1, 3, 5 that are interconnected by a bolt 7.

(5) Rotor stage 3, which is in the middle in FIG. 1 and, viewed in through flow direction 9 of the turbomachine, is second rotor stage 3 of rotor 100, features a through bore 11 through rotor disk 25 of second rotor stage 3, through which bolt shank 13 of bolt 7 is passed or inserted. The cross-sectional shape of through bore 11 is shown in greater detail in FIG. 2. A flange 17 of first rotor stage 1 is configured on axial downstream end region of rotor arm 19. In addition, rotor arm 19 has sealing tips 21 for sealing a possible leakage flow between rotor arm 19 and a guide vane (not shown in FIG. 1).

(6) Bolt 7 has a bolt head 15 that rests against flange 17 of first rotor stage 1. Purely exemplarily, at the periphery thereof, bolt head 15 rests against a shoulder of rotor arm 19. This resting against may act as a locking against rotation upon tightening the connection of the three rotor stages 1, 3, 5. To tighten, respectively secure the connection of the three rotor stages 1, 3, 5, purely exemplarily, bolt shank 13 features a thread on bolt shank end (to the right in FIG. 1) upon which a retaining element, here, exemplarily, a nut 23 is screwed. Other securing options, for example, using a cotter pin are likewise possible.

(7) Third rotor stage 5 (configured on the right in FIG. 1) is likewise connected by a flange 27 and bolt 7 to second rotor stage 3 and indirectly to first rotor stage 1. In contrast to flange 17 of first rotor stage 1, flange 27 of third rotor stage 5 is configured at upstream front end of rotor arm 29 (viewed in through flow direction 9).

(8) Second rotor stage 3 is connected to a shaft 33 of the axial turbomachine. For the sake of clarity, this connection is not explained. The connection may be a keyway connection, for example. First 1 and third 3 rotor stage of rotor 100 according to the present invention are connected to shaft 33 by this connection.

(9) All three rotor stages 1, 3, 5 are bladed, thus have rotor blades 35, 37, 39 that are directed radially outwardly relative to rotor main body 41, 43, 45.

(10) As illustrated in FIG. 1, through bore 11 traversing rotor disk 25 and blades 37 configured on rotor disk 25 may have the same axial position, and/or through bore 11 may be configured in the axial region of extent of blades 37.

(11) FIG. 2 shows a view of a portion of second rotor disk 3 of an inventive rotor 100 having a through bore 11 that has an elliptical cross section.

(12) Relative to the view of FIG. 1, rotor disk 3 is rotated by 90 degrees into the drawing plane. In FIG. 2, circumferential direction u points to the right; axial direction a into the drawing plane.

(13) Purely exemplarily, rotor main body 43 has a dovetailed shape radially r outwardly for connection to a blade root of blade 37 (see FIG. 1). In the same way, the entire rotor, thus blades 37, together with blade roots, rotor main body 43 and rotor disk 25, may have an integral (one piece) design.

(14) In a magnified view, through bore 11, which extends in axial direction a through entire rotor disk 25, is shown as enlarged detail A to the right in FIG. 2. In accordance with the present invention, through bore 11 has an elliptical cross section. In circumferential direction u, major axis 49 of the elliptical cross section is larger than minor axis 51 that is oriented in radial direction r of rotor disk 25. The length, respectively extent of major axis 49 may be referred to as spoke 59. The spoke may be abbreviated as rad. Outer diameter 55, respectively outside diameter relative to radial direction r may be abbreviated as OD; inner diameter 57, respectively inside diameter as ID.

(15) To illustrate this, a round diameter 53 is shown by a dashed line. It would correspond to a bolt bore without the elliptical cross section according to the present invention. This bolt bore would feature a clearance fit relative to the bolt shank diameter, for example. Other fits or bore diameters for a bolt bore would likewise be possible. The elliptical cross section may be manufactured, for example, in such a way that a round through bore is initially produced and an elliptical widening subsequently follows in a spiral milling process, for example.

(16) Elliptical cross section 11 according to the present invention advantageously makes possible a minimized material load of rotor disk 25 in the area of through bore 11. In the case of an operational use of a rotor 100 according to the present invention in a turbomachine, in particular in an aircraft engine, the (mechanical) stress level, as well as the stress amplitude in the area of through bore 11, caused by bolt 7, may take on levels that may lead to a damage and thus to a reduced service life of the component.

(17) In other specific embodiments (not shown) according to the present invention, the cross section of the through bore may have a different non-circular and non-elliptical shape, whose, in particular, maximum dimension, respectively extent in the circumferential direction is larger than in the radial direction, and which likewise makes possible an enhancement as compared to a through bore having a circular cross section.

REFERENCE NUMERAL LIST

(18) r radial; radial direction

(19) a axial; axial direction

(20) u circumferential direction

(21) 100 rotor

(22) 1, 3, 5 rotor stage

(23) 7 fastening element, bolt

(24) 9 through flow direction of the turbine

(25) 11 through bore

(26) 13 shank, shank of the bolt

(27) 15 bolt head

(28) 17 flange of the first rotor stage

(29) 19 rotor arm of the first rotor stage

(30) 21 sealing tips of the first rotor arm

(31) 23 retaining element, nut

(32) 25 rotor disk of the second rotor stage

(33) 27 flange of the third rotor stage

(34) 29 rotor arm of the third rotor stage

(35) 31 sealing tips of the first rotor arm

(36) 33 shaft

(37) 35, 37, 39 blades

(38) 41, 43, 45 rotor main body

(39) 47 blade root of the second rotor stage

(40) 49 major axis of the elliptical cross section

(41) 51 minor axis of the elliptical cross section

(42) 53 diameter of a bolt bore

(43) 55 outside diameter, outer diameter

(44) 57 inside diameter, inner diameter

(45) 59 spoke, length, respectively extent of major axis