Rotor blade shroud for a turbomachine, rotor blade, method of making a rotor blade shroud and a rotor blade

Abstract

The present invention relates to a rotor blade shroud for a turbomachine, comprising a sealing tip and a support structure that abuts the sealing tip. The support structure has at least one intermediate region in which a structural segment is arranged, wherein the radially outwardly arranged surface of the support structure and of the structural segment forms an essentially planar surface. The present invention further relates to a rotor blade for a turbomachine, comprising a rotor blade shroud as well as two methods of manufacturing a rotor blade shroud and a method of manufacturing a rotor blade.

Claims

1. A rotor blade shroud for a turbomachine, comprising: one sealing tip or a plurality of sealing tips and a support structure that abuts the one or plurality of sealing tips, wherein the support structure has at least one intermediate region in which a structural segment is arranged, wherein the radially outwardly arranged surface of the support structure and of the structural segment forms a closed hollow structure, and wherein the at least one intermediate region forms a recess that receives the structural segment.

2. The rotor blade shroud according to claim 1, wherein the support structure and the structural segment comprise the same material, and are formed integrally with each other, being jointly formed in an integrally additive manner.

3. The rotor blade shroud according to claim 1, wherein the support structure is produced from a first material or comprises a first material, and wherein the structural segment is produced from a second material or comprises a second material, wherein the first material and the second material are different.

4. The rotor blade shroud according to claim 1, wherein the support structure has at least two intermediate regions in which two structural segments are arranged.

5. The rotor blade shroud according to claim 1, wherein the one sealing tip or a plurality of sealing tips and/or the support structure is solid in form.

6. The rotor blade shroud according to claim 1, wherein the support structure is arranged between the plurality of sealing tips.

7. The rotor blade shroud according to claim 1, wherein the support structure is rib-shaped in form.

8. The rotor blade shroud according to claim 1, wherein the at least one structural segment has a hollow structure and/or has a lower density than the support structure.

9. The rotor blade shroud according to claim 1, wherein the one sealing tip or a plurality of sealing tips have a width over the periphery that is constant and is aligned perpendicularly to the peripheral direction and/or wherein a second sealing tip is arranged downstream of a first sealing tip, and the second sealing tip is radially displaced outward with respect to the first sealing tip, wherein the first sealing tip and the second sealing tip are arranged essentially parallel to each other in their longitudinal alignment.

10. The rotor blade shroud according to claim 1, wherein the at least one sealing tip is a first sealing tip and a second sealing tip, and wherein the radially outwardly arranged surface of the support structures and of the further structural segments, and/or the surface of the rotor blade shroud that is arranged radially outward between the first sealing tip and the second sealing tip forms a substantially planar surface over an entire periphery thereof.

11. The rotor blade shroud according to claim 1, wherein the rotor blade shroud is configured and arranged in a rotor blade.

12. The rotor blade shroud according to claim 1, wherein the rotor blade shroud is formed by additive manufacturing in one manufacturing step.

13. The rotor blade shroud according to claim 1, including a rotor blade for a turbomachine formed additive manufacturing in one manufacturing step, wherein the rotor blade comprises the rotor blade shroud.

14. A method of manufacturing a rotor blade shroud for a turbomachine, comprising the steps of: providing a rotor blade shroud, comprising at least two sealing tips and a support structure that abuts the at least two sealing tips, wherein the support structure has at least one intermediate region, wherein the intermediate region is a recess; forming, by an additive manufacturing method, of at least one structural segment, and all structural segments, which is or are each arranged in an intermediate region of the support structure, so that, in the case of the manufactured rotor blade shroud, a radially outwardly arranged surface of the support structure and of the structural segments forms a substantially planar surface, wherein the rotor blade shroud forms a closed hollow structure.

Description

BRIEF DESCRIPTION OF THE DRAWING FIGURES

(1) The present invention will be explained by way of example in the following on the basis of the appended drawings, in which identical reference numbers refer to identical or similar structural components. In each of the following figures that are very schematically simplified:

(2) FIG. 1 shows, in a top view from radially outside, a rotor blade shroud that has two sealing tips and a support structure and rotor blade elements arranged below it in accordance with the prior art;

(3) FIG. 2 shows the course of a leakage flow between a rotor blade shroud that has two sealing tips, a support structure, and a housing-side run-in seal in accordance with the prior art;

(4) FIG. 3 shows a simplified illustration of the loss mechanism at a rotor blade shroud in a sectional illustration and in a view from the top in accordance with the prior art;

(5) FIG. 4 shows, in a top view from radially outside, a rotor blade shroud according to the invention, which has two sealing tips, a support structure, and rotor blade elements arranged below it; and

(6) FIG. 5 shows a simplified illustration of the rotor blade shroud according to the invention in a sectional illustration and in a view from the top.

DESCRIPTION OF THE INVENTION

(7) FIG. 1 shows, in a top view from radially outside, a rotor blade shroud 100 with two sealing tips 1a, 1b and a support structure 3 and with rotor blades 5 arranged below it in accordance with the prior art.

(8) The rotor blade shroud 100 (which is referred to in the following as the shroud 100) has two sections, which are arranged in succession in the peripheral direction u and may be referred to as rotor blade shroud sections. Assigned to each section is a rotor blade body 5 arranged below it. The shroud 100 can be fabricated separately or in one piece with the rotor blade body 5.

(9) The shroud 100 has intermediate regions 7, which are surrounded or enclosed by the support structure 3. The webs of the support structure 3 may be referred to as stiffening ribs. The arrangement, the choice of material, and the thickness of the stiffening ribs are intended to make possible a stiffness of the shroud 100 that is as high as possible with, at the same time, a minimization of weight.

(10) The illustrated arrangement of the two segments of the shroud 100 and of the rotor blade bodies 5 continues further in the peripheral direction u, so that a closed rotating wheel or rotor of a rotor stage can be formed.

(11) FIG. 2 shows the course of a leakage flow 9 between a shroud 100 that has two sealing tips 1a, 1b, 1a, a support structure 3, and a housing-side run-in seal 11 in accordance with the prior art.

(12) The run-in seal 11 is fastened to a housing 13. The run-in seal 11 can be honeycomb-shaped in form. The leakage flow 9 flows from upstream with respect to the main through-flow direction 15 to downstream between the sealing tips 1a, 1b and through the run-in seal 11. The leakage flow 9 may be referred to as a gap flow. The gap can be formed in that, when the rotor or the turbomachine is started up, the sealing tips 1a, 1b cut into the run-in seal 11 and form a sealing gap. For an efficiency of the turbomachine that is as high as possible, the flow losses due to the leakage flow 9 should be minimized. This can be achieved, in particular, by a small gap width, but also by flow losses of the leakage flow 9 that are as small as possible and can be caused, for example, by flow separations, turbulences, and other flow phenomena (see FIG. 3).

(13) Furthermore, the distance 17 between the top edge of the support structure 3 and the run-in seal 11 is specified. This distance 17 is relevant in regard to a flow that passes in the peripheral direction u above the support structure 3 and between the sealing tips 1a, 1b. This flow is influenced by the surface structure of the shroud 100 between the sealing tips 1a, 1b.

(14) FIG. 3 shows a simplified illustration of the loss mechanism at a rotor blade shroud 100 in a sectional illustration and in a view from the top in accordance with the prior art.

(15) The lower view in FIG. 3 is a schematically greatly simplified top view of the shroud 100, similar to the illustration of FIG. 1, but without illustration of the rotor blade and without any further details. The leakage flow 9 passes in the direction shown by the arrows over and away from the sealing tips 1a, 1b (alternatively in a direction rotated by 180 degrees). The support structure 3 is likewise illustrated in a greatly simplified manner, without illustration of the individual webs of the support structure 3 in detail. In addition, the inner width 19 of the shroud 100 is indicated in the axial direction a (through-flow direction of the turbomachine), whereby the inner width 19 does not include the width of the two sealing tips 1a, 1b (for which reason, the width is referred to as the inner width 19).

(16) The line of section A-A in the lower view in FIG. 3 marks the illustrated sectional plane of the top view in FIG. 3. The direction of rotation 21 of the shroud 100 in the peripheral direction u applies to both views, upper and lower, in FIG. 3. The direction of rotation 21 can be described in detail by the formula c.sub.u=ω*r, where c.sub.u is the peripheral speed of the rotor, ω (omega) is the angular velocity, and r is the radius of the shroud 100, all with reference to the axis of rotation of the rotor.

(17) In the upper view in FIG. 3, the momentum exchange between the shroud 100 and the run-in seal 11 by means of the flow into the run-in seal 11 and out of the run-in seal 11 is illustrated by the flow arrows 23 in a schematically simplified manner. The lines 24 indicate the backed-up flow at the support structure 3 or at the stiffening ribs of the support structure 3. The shroud 100 moves in the direction of the peripheral speed c.sub.u of the rotor or to the left with reference to the illustration in FIG. 3. On account of the support structure 3 and the intermediate regions 7, the flow backs up or accumulates in front of the stiffening ribs of the support structure 3. The flow pressure accordingly increases (up to the back pressure) and the flow deflects and branches into the run-in seal 11 in accordance with the illustrated flow arrows 23. This deflection of the flow into the run-in seal 11 may be referred to as a so-called “pumping.” In the run-in seal 11, the flow pressure likewise increases on account of the usually honeycomb-shaped structure in the run-in seal 11. When the shroud 100 rotates further in the direction of the peripheral speed c.sub.u of the rotor, the fluid that has previously flowed into the run-in seal 11 will flow back subsequently into the intermediate region 7 once again in the direction of the shroud 100 and afterwards will be strongly accelerated up to the peripheral speed c.sub.u. These permanent and repeating flows can be enhanced still further by turbulences, flow stalls, and other flow phenomena.

(18) The flows 23 into the run-in seal 11 and out of the run-in seal 11 may be referred to as a momentum exchange of the flow. This permanent momentum exchange can cause an increased friction in the flow and slow down the rotor. Furthermore, these flow phenomena can lead to a so-called blending of the flow, which increases the entropy of the leakage flow and thereby degrades the efficiency or increases the efficiency losses.

(19) Further specified in FIG. 3 are the height 25 of the ribs of the support structure 3 and the distance 17 between the stiffening ribs of the support structure 3 and the run-in seal 11.

(20) FIG. 4 shows, in a top view from radially outside, a rotor blade shroud 200 according to the invention that has two sealing tips 1a, 1b and a support structure 3 and a rotor blade element 5 arranged below it.

(21) The rotor blade shroud 200 according to the invention (which is referred to in the following as the shroud 200) has, in addition to the description of the shroud 100 in accordance with the prior art (see FIG. 1), the structural segments 27, which are inserted into the intermediate regions 7.

(22) The radially outwardly arranged surface 29 of the support structure 3 and of the structural segments 27 forms an essentially planar surface 29 (see FIG. 5).

(23) FIG. 5 shows a simplified illustration of the rotor blade shroud 200 according to the invention in a sectional illustration and in a view from the top.

(24) In comparison to the illustration of FIG. 3, the structural segments 27 have been inserted into the intermediate regions 7. As a result, the flow phenomena described in regard to FIG. 3, such as, for example, the so-called pumping of the flow into the run-in seals 11 and out of the run-in seals 11, do not arise. In this way, it is possible to increase the efficiency of the rotor, as already described above in detail, in comparison to the design in accordance with prior art.

(25) The structural segments 27 optionally have inner hollow structures, which can contribute to the reduction in weight of the shroud 200.

(26) Further illustrated in FIG. 5 is the radially outwardly arranged surface 29 of the support structure 3.