Riffled seal for a turbomachine, turbomachine and method of manufacturing a riffled seal for a turbomachine

Abstract

A seal of a turbomachine reduces a leakage flow between a first and second component of the turbomachine. The first component has a first surface and the second component has a second surface, wherein the first component is stiff with regard to a first force exerted perpendicularly thereto and the second component is stiff with regard to a second force exerted perpendicularly thereto. The first surface is opposite the second surface, together defining boundaries of a fluid passage for the leakage flow. The first surface has a first surface riffle. A turbomachine has a seal described above, wherein the turbomachine is a gas turbine engine. A method of manufacturing a first component of a turbomachine with a reduced leakage flow between the first component and a second component of the turbomachine includes fabrication of a first surface riffle, in particular by grinding and/or by electrical discharge machining.

Claims

1. A seal of a turbomachine for reducing a leakage flow through a fluid passage between a first component of the turbomachine and a second component of the turbomachine, the seal comprising the first component with a first surface and the second component with a second surface, wherein the first component is stiff with regard to a first force exerted perpendicularly to the first surface; the second component is stiff with regard to a second force exerted perpendicularly to the second surface; the first surface is opposite to the second surface; and the first surface comprises a first surface riffle, wherein the fluid passage is defined by the first and second components that are spaced apart, and wherein the first surface riffle is angled substantially perpendicularly to the leakage flow through the fluid passage.

2. The seal according to claim 1, wherein the first surface riffle comprises a plurality of notches.

3. The seal according to claim 2, wherein each notch has at least one of a depth, a width and a length that is optimized for reducing the leakage flow.

4. The seal according to claim 1, wherein the turbomachine comprises an axis of rotation and the first surface and the second surface are substantially extending radially from the axis of rotation or the first surface and the second surface are substantially extending parallel to the axis of rotation.

5. The seal according to claim 1, wherein the first component comprises a third surface and the second component comprises a fourth surface; the third surface is opposite to the fourth surface; and the third surface comprises a third surface riffle and/or the fourth surface comprises a fourth surface riffle.

6. The seal according to claim 5, wherein the second surface is substantially parallel to the third surface and the fourth surface.

7. The seal according to claim 5, wherein the third surface and the fourth surface define boundaries of the fluid passage for the leakage flow.

8. The seal according to claim 1, wherein the seal further comprises a leakage flow access side, a leakage flow exit side and a seal strip with a horizontal seal strip extension and a vertical seal strip extension; wherein a direction of a differential pressure between the leakage flow access side and the leakage flow exit side is substantially perpendicular to the horizontal seal strip extension.

9. The seal according to claim 1, wherein the first component is a rotatable part and/or a static part of the turbomachine, and the second component is a rotatable part and/or a static part of the turbomachine.

10. The seal according to claim 1, wherein the first component is a first part of a first turbine blade and the second component is a second part of the first turbine blade or the second part of a second turbine blade.

11. The seal according to claim 1, wherein the first component is a first part of a first stator vane and the second component is a second part of the first stator vane or the second part of a second stator vane.

12. A turbomachine comprising a seal according to claim 1, wherein the turbomachine is a gas turbine engine.

13. The turbomachine according to claim 12, wherein the seal is located in a turbine section of the turbomachine and/or in a compressor section of the turbomachine.

14. The seal according to claim 1, wherein the first surface and the second surface define boundaries of the fluid passage for the leakage flow.

15. A seal of a turbomachine for reducing a leakage flow between a first component of the turbomachine and a second component of the turbomachine, the seal comprising the first component with a first surface and a third surface and the second component with a second surface and a fourth surface, wherein the first component is stiff with regard to a first force exerted perpendicularly to the first surface; the second component is stiff with regard to a second force exerted perpendicularly to the second surface; the first surface is opposite to the second surface; the first surface comprises a first surface riffle; the third surface is opposite to the fourth surface; and the second surface comprises a second surface riffle, the third surface comprises a third surface riffle and/or the fourth surface comprises a fourth surface riffle, wherein the seal is configured such that the leakage flow is diverted by a diversion angle of greater than 135 degree, between the first surface riffle and the third surface riffle and/or between the first surface riffle and the fourth surface riffle.

16. The seal according to claim 15, wherein the seal is configured such that the leakage flow is diverted by a diversion angle of greater than substantially 180 degree, between the first surface riffle and the third surface riffle and/or between the first surface riffle and the fourth surface riffle.

17. A method of manufacturing a first component of a turbomachine with a reduced leakage flow between the first component and a second component of the turbomachine, the first component comprising a first surface and the second component comprising a second surface, the first surface being opposite to the second surface, particularly the first surface and the second surface defining boundaries of a fluid passage for the leakage flow; the method comprising fabrication of a first surface riffle in the first surface, by grinding and/or by electrical discharge machining.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings, of which:

(2) FIG. 1: shows a riffled seal of a turbomachine and parts of the turbomachine in a cross-sectional view;

(3) FIG. 2: shows a riffled seal in a cross-sectional view;

(4) FIG. 3: shows a seal and parts of a nozzle segment in a cross-sectional view;

(5) FIG. 4: shows a mortise and tenon joint with a riffled seal in a cross-sectional view;

(6) FIG. 5: shows a circumferential surface riffle; and

(7) FIG. 6: shows a chordal surface riffle.

(8) The illustration in the drawing is schematically. It is noted that for similar or identical elements in different figures, the same reference signs will be used.

DETAILED DESCRIPTION OF THE DRAWINGS

(9) Referring to FIG. 1, a riffled seal of a turbomachine and parts of the turbomachine in a cross-sectional view in a plane perpendicularly to an axis of rotation 66 of the turbomachine are shown. Exemplarily, parts of rotor blades and parts of a rotor disc are illustrated. A first component 11 of the turbomachine comprises a firtree-shaped root and a platform. An aerofoil 56 is joined with the first component 11. Next to the first component 11, a second component 21 of the turbomachine is located. The second component 21 similarly comprises a firtree-shaped root and a platform.

(10) Also an aerofoil 56 is joined with the second component 21. The first component 11 and the second component 21 are separated by a fluid passage. A part of the surface of the first component 11 is denoted by a first surface 12. The first surface 12 comprises a first surface riffle 13.

(11) Opposite to the first surface 12 a second surface 22 is located. Finally, the seal shown in FIG. 1 also comprises a seal strip 52, which is located in a pair of slotseach in one of the roots or platformsperpendicularly to a direction of a differential pressure.

(12) It should be noted that this invention is independent to the seal strip 52 and its slots. The invention can be used in a serial arrangement, upstream or downstream of the conventional seal strip 52 to improve the sealing performance or it may be used on its own with no seal strip 52 present at all.

(13) In FIG. 2 a riffled seal 51 according to the invention is exemplarily shown in a cross-sectional view in more detail. The seal 51 comprises again a first component 11 of a turbomachine with a first surface 12 and a second component 21 of a turbomachine with a second surface 22. The first surface 12 comprises a first surface riffle 13. The first surface riffle 13 comprises a plurality of notches. One of the plurality of notchesidentified as notch 61is characterised by a notch depth 62 and a notch width 63. In FIG. 2, the plurality of notches comprises notches which feature a round, curved shape.

(14) The first surface 12 and the second surface 22 are separated by a fluid passage 59 which width is denoted by a surface distance 57. Furthermore, the seal 51 comprises a leakage flow access side 54 and a leakage flow exit side 55, defining thus a direction 58 of a differential pressure. As an example, in FIG. 2 a gas path of the turbomachine is conducted at the leakage flow exit side 55 in the upper part of the drawing, whereas in the lower part of the drawing, at the leakage flow access side 54, a radially inner section with a cavity 67 is situated. Therefore, the seal 51 reduces an undesired ingress of gases from the inner section into the gas path via the fluid passage 59 between the first component 11 and the second component 21. More specifically, a leakage flow 53 is diverted, deflected and slowed down in a region of the first surface riffle 13. Thus a tortuous leakage flow 53 in that region results, leading to an overall reduction of the leakage flow 53.

(15) FIG. 2 additionally shows another feature to reduce the leakage flow 53. A seal strip 52, comprising a horizontal seal strip extension 52a and a vertical seal strip extension 52b, is introduced into a leak path of the leakage flow 53. The leakage flow 53 is thus split into two fractions and guided along a number of edges.

(16) FIG. 3 shows a seal 51 and parts of a nozzle segment in a cross-sectional view in a plane through an axis of rotation 66 of a turbomachine. A stator vane 68 with a mortise and tenon joint can be identified. The tenon refers to a first component 11 of the turbomachine, the mortise to a second component 21.

(17) FIG. 4 shows a mortise and tenon joint with a riffled seal 51 in more detail. The tenon is also referred to as a lug or a rail, particularly for an interface between a guide vane and a guide carrier. In FIG. 4, the tenon refers to a first component 11 of a turbomachine, the mortise to a second component 21. In the drawing, a leakage flow access side 54 is on the left, a leakage flow exit side 55 on the right.

(18) Thus, a direction 58 of a differential pressure is pointing from left to right. The first component 11 comprises a first surface 12 with a first surface riffle 13. The second component 21 comprises a second surface 22 which is opposite to the first surface 12. Parallel to the first surface 12 is located the third surface 31, which is also comprised by the first component 11. The third surface 31 comprises a third surface riffle 32, which is opposite to a fourth surface 41. The fourth surface 41 is comprised by the second component 21.

(19) An effect of the tenon on the leakage flow 53 is that the tenon acts as a barrier to the leakage flow 53. An effect of the first surface riffle 13 and the second surface riffle 32 is that they force the leakage flow 53 into a tortuous path. By these measures, the leakage flow is thus reduced highly efficiently.

(20) FIGS. 5 and 6 show embodiments of a surface riffle located on a surface in axial direction. In FIG. 5, a first surface riffle 13 on a first component 11 is shown. The first surface riffle 13 comprises four notches 61. Due to the curved shape of the notches 61, i.e. the curved shape of respective notch lengths, the first surface riffle 13 can be denoted as a circumferential surface riffle. Furthermore and in the shown example, it can be seen that the notches 61 stop shortly before a rim or edge of the first component 11. The reason for that is an avoidance of an extra leak path from a first side 64 of the first component 11 along a notch 61 to a second side 65 of the first component 11.

(21) Finally, in FIG. 6, a first surface riffle 13 on a first component 11 is shown. The first surface riffle 13 comprises four notches 61. The notches 61 feature a shape of a straight line and can thus be denoted as a chordal surface riffle. An advantage of this shape is e.g. easing of manufacture.

(22) It should be noted that the term comprising does not exclude other elements or steps and a or an does not exclude a plurality. Also elements described in association with different embodiments may be combined. It should also be noted that reference signs in the claims should not be construed as limiting the scope of the claims.