Seal segment for a turbine, assembly for externally delimiting a flow path of a turbine, and stator/rotor seal

Abstract

A seal segment for a turbine and an assembly for sealing the gaps between seal segments and stator vanes of a turbine. The seal segments have a plate-shaped wall, the first lateral surface of which faces the vane tips in the assembled state of the seal segments, is surrounded by a closed circumferential edge, and can be divided into four lateral wall sections, and the plate-shaped wall has a seal element which is arranged over the entire surface of the lateral surface. A number of seal lamellae which are secured on one side are provided on at least one of the lateral wall sections and/or on at least one of the seal lateral wall sections facing adjacent seal segments when the seal segments are assembled in a turbine so as to form a ring in order to reduce a flow along the corresponding lateral wall section.

Claims

1. A sealing segment for a turbine, for assembly with further sealing segments in the turbine, for sealing off a gap between the sealing segments and rotor blades of the turbine or to form a seal constituent part of a stator-rotor seal, the sealing segment comprising: a plate-like wall which comprises a first side surface which, in an installed state of the sealing segment, faces blade tips of the rotor blades or the other seal constituent part, and an edge which surrounds the first side surface in a closed, peripheral manner and on which multiple side wall sections abut the first side surface, and a sealing element which is arranged on the first side surface over a full surface area thereof and which, analogously to the plate-like wall, comprises sealing side wall sections, and a number of sealing lamellae provided on at least one of the side wall sections, and/or on at least one of the sealing side wall sections, and for sealing segments assembled to form a ring in a turbine face adjacent sealing segments of the respective ring, wherein the number of sealing lamellae are adapted for reducing flow along the respective side wall section in an axial direction from upstream to downstream, wherein the respective sealing lamellae project at an angle of less than 90° from the side wall sections or sealing side wall sections.

2. The sealing segment as claimed in claim 1, wherein the respective sealing lamellae extend transversely with respect to the flow direction of a working medium flowing in the turbine, or to a leakage flow.

3. The sealing segment as claimed in claim 2, wherein the respective sealing lamellae extend transversely with respect to the flow direction of a working medium flowing in the turbine, or to a leakage flow, and relative to their installation position in a turbine, in a circumferential direction and in a radial direction.

4. The sealing segment as claimed in claim 1, wherein the sealing lamellae are curved toward their free end.

5. The sealing segment as claimed in claim 1, wherein the sealing element is designed in the form of a honeycomb structure.

6. The sealing segment as claimed in claim 5, wherein the sealing lamellae are parts of the honeycomb structure.

7. The sealing segment as claimed in claim 1, wherein the sealing element is designed in the form of a strippable coating system having one or more layers.

8. The sealing segment as claimed in claim 1, wherein at least the sealing lamellae are produced by an additive manufacturing method.

9. An arrangement for sealing off the gaps between sealing segments and rotor blades of a turbine, comprising: a multiplicity of sealing segments as claimed in claim 1 arranged so as to form a segmented ring, such that the sealing lamellae of a first sealing segment bear against an opposite side wall section or sealing side wall section of a further sealing segment, which is directly adjacent to the first sealing segment, in a pre-stressed manner and a longitudinal flow through the abutting joint, which joint forms between the adjacently arranged first and second sealing segments, in an axial direction from upstream to downstream is able to be avoided to the greatest extent.

10. A stator-rotor seal, comprising: a multiplicity of sealing segments as claimed in claim 1 arranged so as to form a segmented ring, such that the sealing lamellae of a first sealing segment bear against an opposite side wall section or sealing side wall section of a further sealing segment, which is directly adjacent to the first sealing segment, in a pre-stressed manner and a longitudinal flow through the abutting joint, which joint forms between the adjacently arranged first and second sealing segments, in an axial direction from upstream to downstream is able to be avoided to the greatest extent.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) In the figures:

(2) FIG. 1 shows, in a schematic illustration, an exemplary embodiment of a sealing segment according to the invention, with non-essential features for the invention not being illustrated,

(3) FIG. 2 shows a detail of an arrangement, for delimiting a flow path of a turbine, during assembly,

(4) FIG. 3 shows a detail from an arrangement with two sealing segments situated in their operating position, and

(5) FIG. 4 shows a second exemplary embodiment, analogous to FIG. 2, with sealing lamellae on two side wall sections per sealing segment.

DETAILED DESCRIPTION OF INVENTION

(6) FIG. 1 schematically shows, in a perspective illustration, a first exemplary embodiment of a sealing segment 10 according to the invention which is able to be assembled with further such segments in a turbine on a turbine guide vane carrier in order to seal off a gap between the segments and the rotor blades (not illustrated) of said turbine as much as possible. The sealing segments can also be assembled to form a ring which is used as a seal constituent part of a advantageously labyrinthine stator-rotor seal.

(7) In terms of its shape, the sealing segment 10 is substantially plate-like and rectangular and comprises a corresponding wall 12 whose first side surface 14, in the installed state, faces the blade tips of rotor blades (not illustrated) or the rotor. The rotor blades may be both free-standing, that is to say shroudless, rotor blades, and shroud rotor blades. The wall 12 has a second side surface 15, which is opposite the first side surface. In the installed state, said second side surface faces the turbine guide vane carrier (not illustrated). For fastening the sealing segment 10 to the turbine guide vane carrier, grooves 17 are provided. Instead of these, it would also be possible for hooks to be provided on the second side surface 15.

(8) The side surface 14 is surrounded by a closed peripheral edge 16. Owing to the rectangular shape of the wall 12, four side wall sections 16a-16d abut the side surface 14 on the edge 16. In the exemplary embodiment shown, in each case two side wall sections, 16a and 16c and also 16b and 16d, are parallel to one another, wherein, when the sealing segment 10 has been installed in a turbine, the pair of side wall sections 16b, 16d is arranged parallel to the throughflow direction of the working medium of the turbine or to the leakage flow. The side wall sections 16b, 16d could also be inclined in relation to the throughflow direction of the working medium, with an angle not equal to 90° being formed. The throughflow direction is understood to mean substantially the axial direction A of the turbine.

(9) Provided in the side walls 16b, 16d in each case are grooves 31, of which merely one is able be seen owing to the perspective illustration. In the case of sealing segments 10 assembled to form a ring, said grooves 31 are opposite one another such that conventional, plate-like seals (not illustrated) are seated therein. The abutting joints 24 present between the (sealing) side walls of adjacent sealing segments 10 can thereby be sealed off against leakage into the rear, that is to say radially outer, region of the turbine. In other words, flow through the abutting joint 24 from the inside, that is to say from the flow channel, outward, that is to say toward the turbine guide vane carrier, is consequently suppressed to the greatest extent.

(10) Arranged on the first side surface 14 of the wall 12 is a sealing element 18 which, according to this exemplary embodiment, is designed in the form of a honeycomb structure 19 (FIG. 2). Analogously to the wall 12, the sealing element 18 comprises four sealing side wall sections 18a-18d.

(11) Both the side wall sections 16a, 16c and the sealing side wall sections 18a, 18c are consequently situated one behind the other with respect to the throughflow direction such that, for example, the side wall section 16a and the sealing side wall section 18a are arranged upstream of the side wall section 16c and the sealing side wall section 18c.

(12) Provided on at least one of those side wall sections, and/or on at least one of those sealing side wall sections 18b, which, in the case of sealing segments assembled to form a ring in a turbine, face adjacent sealing segments of the respective ring are a number of sealing lamellae 20 for reducing flow along the respective side wall section 16b or sealing side wall section 18b. According to the exemplary embodiment illustrated in FIG. 1, four lamellae are provided. A greater number, as shown in FIG. 2 by way of example, is also advantageous.

(13) The respective sealing lamellae 20 project at an angle α, which may be less than 90°, from planar surfaces of the sealing side wall sections 18b or side wall sections 16b. According to a first exemplary embodiment, the angle α may be 60°. Said lamellae extend so as to be curved in a leaf spring-like manner from their first end 20a to their free end 20b.

(14) If for example the sealing element is designed in the form of a honeycomb structure, the lamellae may be part of the honeycomb structure and—as viewed in the circumferential direction—project beyond the side wall section 16b.

(15) FIG. 2 shows, in a schematic illustration, a plan view of two sealing segments 10a, 10b, designed as per FIG. 1, during the assembly for forming an arrangement 22. The honeycomb structure 19 is illustrated merely schematically. During the assembly, the two directly adjacent sealing segments 10a, 10b are moved toward one another according to one of the arrows M such that the sealing lamellae 20 fastened on one side to the first sealing segment, which can be seen as sealing segment 10a in FIG. 2, come into abutment with the side wall section 18d of the adjacent sealing segment, which is referred to as sealing segment 10b in FIG. 2. In the operating position, illustrated in FIG. 3, the sealing lamellae 20 are elastically bent and then bear against the side wall section 18d of the adjacent sealing segment 10b in a pre-stressed manner.

(16) Longitudinal flow through said abutting joint 24 with working medium, or with the leakage flow, in the axial direction from upstream to downstream is thus avoided to the greatest extent.

(17) FIG. 3 shows the two sealing segments 10a, 10b in their operating position, in which the sealing lamellae 20 of the first sealing segment 10a bear against the contact surface of the second sealing segment 10b (sealing side wall section 18d) in a pre-stressed manner owing to the small spacing between the two sealing segments 10a, 10b.

(18) The arrow R indicates the direction of rotation of the rotor blades with respect to the sealing segments 10. Here, it is an advantage if the direction of rotation is, where possible, directed from the fastened end 20a of the sealing lamellae 20 to the free end 20b thereof.

(19) Alternatively, and as shown in FIG. 4, it is possible for the sealing lamellae 20, which follow one another along the abutting joint 24, to be fastened in an alternating manner to the ring segments 10a, 10b involved. In this case, sealing lamellae 20 are arranged not only on one side wall section (cf. FIG. 2, 18b) but on two side wall sections 18b and 18d.

(20) Overall, the invention thus relates to a sealing segment 10 for a turbine and to an arrangement for sealing off the gaps between sealing segments 10 and rotor blades of a turbine, wherein the sealing segments comprise a plate-like wall 12 whose first side surface 14, which, in the installed state of the sealing segments, faces the blade tips of rotor blades, is surrounded by a closed peripheral edge 16 and is able to be subdivided into four side wall sections 16a-16d, and comprise, on the side surface 14, a sealing element 18 arranged over the full surface area thereof. In order to further minimize or even to prevent a local flow which possibly occurs between directly adjacent sealing segments 10, the provision on at least one of those side wall sections 16a-16d, and/or on at least one of those sealing side wall sections 18a-18d, which, in the case of sealing segments assembled to form a ring in a turbine, face adjacent sealing segments of the respective ring, of a number of sealing lamellae 20 for reducing flow along the respective side wall section is proposed.