# US 8,770,938 B2 · Rotor for an axial-throughflow turbomachine and moving blade for such a rotor

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- Number: US 8,770,938 B2
- Document ID: US8770938B2
- Status: Granted
- Kind: B2
- Application number: 12/942,565
- Filed: 2010-11-09
- Published: 2011-05-12
- Granted: 2014-07-08
- Earliest claimed: 2009-11-10
- Assignees: ALSTOM Technology Ltd
- Applicants: Erich Kreiselmaier; Kurt Rubischon; Christoph Nagler; Herbert Brandl
- Inventors: Erich Kreiselmaier; Kurt Rubischon; Christoph Nagler; Herbert Brandl
- Web page: https://patentgrep.com/patent/US8770938B2

## CPC

- F01D 5/3038: {the slot having inwardly directed abutment faces on both sides}
- F05D 2230/232: by welding
- F05D 2250/14: elliptical
- F05D 2250/141: circular
- F05D 2250/70: Shape
- F05D 2250/71: curved
- F05D 2260/941: particularly aimed at mechanical or thermal stress reduction
- F01D: NON-POSITIVE DISPLACEMENT MACHINES OR ENGINES, e.g. STEAM TURBINES (machines or engines for liquids F03; non-positive displacement pumps F04D)
- F05D: INDEXING SCHEME FOR ASPECTS RELATING TO NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES, GAS-TURBINES OR JET-PROPULSION PLANTS

## Abstract

A rotor is provided for an axial-throughflow turbo machine, which carries a plurality of moving blades which are each pushed with a blade root into a rotor groove extending about the axis and are held. The blade root includes a hammer root with a hammerhead and is supported on radial stop faces of the rotor groove which lie further outward in the radial direction, against centrifugal forces acting on the moving blades, and are supported on axial stop faces lying further inward in the radial direction, against axial forces which act on the moving blade. The rotor groove has at its bottom, to reduce thermal stresses, an axially and radially widened bottom region with a continuously curved cross-sectional contour. In such a rotor, an advantageous adaptation of the blading is achieved by the blade root of the moving blades being adapted to the widened bottom region in the radial direction.

## Claims

### Claim 1

A rotor for an axial-throughflow turbomachine, the rotor carries a plurality of moving blades which are pushed, in each case, with a blade root into a rotor groove extending about an axis and are held there, with the blade root comprising a hammer root with a hammerhead and being supported on radial stop faces of the rotor groove which lie further out in the radial direction, against centrifugal forces which act on the plurality of moving blades, and being supported on axial stop faces lying further inward in the radial direction, against axial forces which act on the plurality of moving blades, the rotor groove having at a bottom portion, in order to reduce thermal stresses, an axially and radially widened bottom region with a continuously curved cross-sectional contour, wherein the bottom region radially extends beyond a lowermost stop face, and the bottom region is axially widened beyond the radial and axial stop faces, the blade root of the plurality of moving blades is adapted to the widened bottom region in a radial direction; and
wherein the widened bottom region has a predetermined maximum width (d1) in an axial direction, the radial stop faces have a predetermined minimum distance (d5) in the axial direction, and a ratio of the minimum distance (d5) to the maximum width (d1) is between 0.1 and 0.6, namely 0.1<d5/d1<0.6 the widened bottom region has a predetermined first maximum depth (d4) in relation to the radial stop faces, the widened bottom region has a predetermined second maximum depth (d3) in relation to inner edges of the axial stop faces, and a ratio of the second maximum depth (d3) to the first maximum depth (d4) is between 0.4 and 0.9, namely 0.4<d3/d4<0.9.

### Claim 2 (depends on 1)

The rotor as claimed in claim 1, wherein the widened bottom region is formed mirror-symmetrically to a mid-plane passing through the rotor groove and standing perpendicularly to the axis, and a radius of curvature of the cross-sectional contour of the bottom region increases from the mid-plane towards the margin.

### Claim 3 (depends on 1)

The rotor as claimed in claim 1, wherein a plurality of identical rotor grooves are provided, offset at a predetermined distance (d2), in the axial direction, and a ratio of the maximum width (d1) to the distance (d2) is between 0.5 and 0.8, namely 0.5<d1/d2<0.8.

### Claim 4 (depends on 1)

The rotor as claimed in claim 1, wherein a lengthening bolt extending in the radial direction is integrally formed onto the blade root below the hammerhead in order to bridge the radial widening of the widened bottom region.

### Claim 5 (depends on 4)

The rotor as claimed in claim 4, wherein an interspace remains free between a lower end of the lengthening bolt and the bottom of the widened bottom region, and the free interspace has arranged in it a spring which presses the moving blade with the blade root against the radial stop faces in the radial direction.

### Claim 6 (depends on 1)

A moving blade for a rotor as claimed in claim 1, the moving blade comprising a blade root designed as a hammer root with a hammerhead the blade root is extended in the radial direction below the hammerhead in order to bridge the radial widening of the widened bottom region of the rotor groove.

### Claim 7 (depends on 6)

The moving blade as claimed in claim 6, wherein a lengthening bolt extending radially is provided for lengthening the blade root.

### Claim 8 (depends on 7)

The moving blade as claimed in claim 7, wherein the lengthening bolt is integrally formed on the hammerhead.

### Claim 9 (depends on 7)

The moving blade as claimed in claim 7, wherein a curved transitional face is provided at a transition between the lengthening bolt and the hammerhead in order to ensure a continuous transition.

### Claim 10 (depends on 7)

The moving blade as claimed in claim 7, wherein the lengthening bolt is produced as a separate part and is connected to the hammerhead.

### Claim 11 (depends on 10)

The moving blade as claimed in claim 10, wherein the lengthening bolt is screwed onto the hammerhead.

### Claim 12 (depends on 10)

The moving blade as claimed in claim 10, wherein the lengthening bolt is welded to the hammerhead.

### Claim 13 (depends on 6)

The moving blade as claimed in claim 6, further comprising mass-reducing recesses provided in the blade root.

### Claim 14 (depends on 13)

The moving blade as claimed in claim 13, wherein the recesses extend over the hammerhead and the lengthening bolt.

### Claim 15 (depends on 13)

The moving blade as claimed in claim 13, wherein the recesses extend in a circumferential direction.

### Claim 16 (depends on 13)

The moving blade as claimed in claim 13, wherein the recesses extend in a radial direction.

### Claim 17

A rotor for an axial-throughflow turbomachine, the rotor carries a plurality of moving blades which are pushed, in each case, with a blade root into a rotor groove extending about an axis and are held there, with the blade root comprising a hammer root with a hammerhead and being supported on radial stop faces of the rotor groove which lie further out in the radial direction, against centrifugal forces which act on the plurality of moving blades, and being supported on axial stop faces lying further inward in the radial direction, against axial forces which act on the plurality of moving blades, the rotor groove having at a bottom portion, in order to reduce thermal stresses, an axially and radially widened bottom region with a continuously curved cross-sectional contour, wherein the bottom region radially extends beyond a lowermost stop face, and the bottom region is axially widened beyond the radial and axial stop faces, the blade root of the plurality of moving blades is adapted to the widened bottom region in a radial direction;
wherein a lengthening bolt extending in the radial direction is integrally formed onto the blade root below the hammerhead in order to bridge the radial widening of the widened bottom region; and
wherein the hammerhead has a predetermined height (d7), the lengthening bolt has a predetermined radial length (d6), and the ratio of height to length (d7/d6) is between 0.2 and 0.8, namely 0.2<d7/d6<0.8, the hammerhead has a predetermined first axial width (d8), the lengthening bolt has a predetermined second axial width (d9), and a ratio of the second to the first axial width (d9/d8) is between 0.2 and 0.6, namely 0.2<d9/d8<0.6.

### Claim 18

A rotor for an axial-throughflow turbomachine, the rotor carries a plurality of moving blades which are pushed, in each case, with a blade root into a rotor groove extending about an axis and are held there, with the blade root comprising a hammer root with a hammerhead and being supported on radial stop faces of the rotor groove which lie further out in the radial direction, against centrifugal forces which act on the plurality of moving blades, and being supported on axial stop faces lying further inward in the radial direction, against axial forces which act on the plurality of moving blades, the rotor groove having at a bottom portion, in order to reduce thermal stresses, an axially and radially widened bottom region with a continuously curved cross-sectional contour, wherein the bottom region radially extends beyond a lowermost stop face, and the bottom region is axially widened beyond the radial and axial stop faces, the blade root of the plurality of moving blades is adapted to the widened bottom region in a radial direction;
the moving blade comprising a blade root designed as a hammer root with a hammerhead, the blade root is extended in the radial direction below the hammerhead in order to bridge the radial widening of the widened bottom region of the rotor groove;
wherein a lengthening bolt extending radially is provided for lengthening the blade root; and
wherein the hammerhead has a predetermined height (d7), the lengthening bolt has a predetermined radial length (d6), and a ratio of height to length (d7/d6) is between 0.2 and 0.8, namely 0.2<d7/d6<0.8.

### Claim 19 (depends on 18)

The moving blade as claimed in claim 18, wherein the hammerhead has a predetermined first axial width (d8), the lengthening bolt has a predetermined second axial width (d9) and a ratio of the second to the first axial width (d9/d8) is between 0.2 and 0.6, namely 0.2<d9/d8<0.6.