EP3139007A1 - Device for limiting a flow channel of a turbomachine - Google Patents

Abstract

The invention relates to a device for defining a flow channel of a turbomachine, having a wall which has a plurality of wall segments viewed in the circumferential direction of the turbomachine, and having a plurality of outer segments which radially surround the wall segments, wherein each wall segment a uniformly curved first cross-sectional contour, wherein each outer segment comprises at least one second cross-sectional contour which deviates from the uniformly curved first cross-sectional contour, wherein the second cross-sectional contour has a plurality of depressions, which are directed in the radial direction of the gas turbine inwardly and of which at least a part of the radially outer surface of an associated Wandungssegments is attached.

Description

The invention relates to a device for limiting a flow channel of a turbomachine, for example a gas turbine.

In turbomachines, such as gas turbines, an annular hot gas channel between two vanes is often bounded radially outwardly by an annular wall. The wall can be segmented in the circumferential direction of the turbomachine to allow thermally induced expansions of the outer wall during operation of the turbomachine. In addition, on the side facing the hot gas channel radially inner side of the wall sealing elements, such as honeycomb seals, or inlet linings may be provided. In this case, the wall also acts as a seal carrier to minimize a radial gap between the blades and the wall. On the side facing away from the hot gas channel side of the wall may also be arranged a plurality of circumferentially adjacent heat shields to radially outwardly located components of the housing of the turbomachine to protect against the temperatures in the hot gas duct.

In general, the heat shields face with their center regions the gaps between the seal carriers. During operation, some of the hot gas may flow into the gaps between the seal carriers, thereby overheating their end portions. In addition, cooling air usually flows through gaps between the heat shields and impinges on the already cooler center regions of the seal carriers. This results in high temperature gradients within the seal carrier, which can lead to cracks.

The paper titled "Design modification to enhance the fatigue life of an aero-engine heat shield" describes how cracking is prevented by modifications to the heat shields. Stiffeners are welded to the heat shields. The disadvantage here is the increase in weight of the arrangement due to the welded stiffeners.

The publication EP 1 876 310 A2 discloses structured sheets for use in vehicle components, especially for heat shields. The structures are each wave-shaped in two directions of expansion, so that a multiplicity of raised and recessed projections with steep flanks are distributed over the entire surface. Two structured sheets are stacked on top of each other, with a sheet resting on the flanks of the structure of the second sheet. For this special support high manufacturing accuracy is required, which entails increased component costs. In addition, the two sheets per se and in particular in their combination are susceptible to deformation by high temperatures. In this case, the two sheets can move against each other, whereby the reliability is reduced.

The publication US 2003/0000675 A1 relates to a method for producing a spatially shaped layer of a hard and brittle material for use in gas turbines. Two such bonded layers together form a honeycomb structure which serves to seal between turbine blades and a stator. The honeycomb structure is thus designed for wear and thus unsuitable for preventing cracking in a component.

The invention is therefore based on the object to provide a device for limiting a flow channel of a turbomachine, the flow channel side wall is robust, but it has a low weight, can be manufactured with little effort and ensures high reliability.

This object is achieved with a device according to claim 1. Advantageous embodiments of the invention are contained in the subclaims.

According to the invention, the solution of the problem in an apparatus for limiting a flow channel of a turbomachine, such as a gas turbine whose wall is divided in the circumferential direction of the gas turbine into a plurality of Wandungssegmenten. In addition, the device in the circumferential direction of the gas turbine has a plurality of outer segments, which surround the Wandungssegmente radially outward. Each wall segment has a uniformly curved first cross-sectional contour in the circumferential direction. Each outdoor segment includes at least one second cross-sectional contour deviating from the uniformly curved first cross-sectional contour, the second cross-sectional contour having a plurality of counterbores inwardly directed in the radial direction of the gas turbine and at least a portion of which is secured to the outer surface of an associated wall segment. "A uniformly curved first cross-sectional contour" corresponds to a ring segment in the geometric sense.

The advantage of the solution according to the invention is that the cross-sectional contoured outer segments serve as reinforcement for the wall segments, wherein the bending resistance moment of the wall segments is increased. A rigidity of the wall segments is increased by the outer segments, for example heat shields, which counteracts the formation of cracks in the wall segments. At the same time a uniform air mixing between the outer segments and the wall segments is achieved, are reduced by the temperature gradients in the Wandungssegmenten, which also counteracts the formation of cracks. Consequently, the device is characterized by a robust flow channel side wall. Due to the cross-sectional contour of the outer segments, only small contact surfaces to the Wandungssegmenten, whereby only a small heat transfer from the Wandungssegmenten to the outer segments takes place. The outer segments thus effect a functional integration of a heat shield and a conventional reinforcing sheet. This feature integration allows for weight savings, reducing manufacturing and operating costs. In addition, space is saved within the turbomachine. In other words, the wall of the flow channel is reinforced in order to prevent thermally induced cracks, wherein in a preferred embodiment, heat shields are used for the reinforcement of the wall. In this way, the heat shields fulfill a dual functionality, namely for the protection of radially outer gas turbine components against hot gas channel side heat radiation and on the other structural stiffening of the wall of the hot gas channel.

According to an advantageous development of the invention, the second cross-sectional contour comprises in addition to the plurality of counterbores a plurality of elevations. As a result, the bending resistance torque of the outer segments is further increased. So it is the stability of the outer ring and thus further increases the composite arrangement of one outer segment and one wall segment.

In a particular embodiment of the invention, the circumferential length of an outer segment may be equal to the circumferential length of an associated Wandungssegments and each an outer gap between two outer segments and an inner gap between two Wandungssegmenten opposite each other in the radial direction. Thus, cooling air, which is guided inwardly through the outer column, can cool countercurrent hot gas, which pushes outward through the inner gaps, directly at the exit from the turbine chamber.

In addition, a sealing element can be attached to each outer segment, which covers an associated outer gap. The cover of the outer gap serves to reduce the leakage of hot gas.

In an alternative embodiment of the invention, the circumferential length of an outer segment can be equal to the circumferential length of an associated Wandungssegments and the outer segments can be arranged offset relative to the Wandungssegmenten in the circumferential direction of the gas turbine. Cooling air and hot gas flows do not collide directly here with one another, but rather flow in the circumferential direction of the gas turbine offset from one another into the intermediate space between one outer segment and one wall segment. As a result, the cooling air can be directed onto the hot gas which is forced out of the turbine space with little loss, in order to cool it.

In addition, a spring element for supporting on a housing portion of the turbomachine can be arranged on each outer segment. As a result, the Wandungssegmente and the outer segments are acted upon with a radially inwardly directed spring force, which keep the Wandungssegmente regardless of the operating condition, maneuvers and the like in their desired position. In addition, the spring element can act as a sealing lip. Preferably, the spring elements, also a second cross-sectional contour. For example, the spring elements in the circumferential direction of the gas turbine are sinusoidal in cross-section and provided with countersinks and / or elevations.

In a specific development of the invention, at least one cover element is fastened to the outer segment in the circumferential direction of the turbomachine, the cover element in particular attached to elevations of the second cross-sectional structure of the outer segment. This creates a sandwich structure. The stability of the arrangement of one outer segment and one wall segment is further increased by the cover element.

Furthermore, the cover element may have a uniformly curved first cross-sectional contour. A uniformly curved first cross-sectional contour is easy to manufacture and can be easily attached to an outer segment.

In addition, a jet engine may comprise the device.

Alternatively, a stationary gas turbine may comprise the device.

Fig. 1

eine axiale Schnittansicht einer erfindungsgemäßen Vorrichtung gemäß einem ersten Ausführungsbeispiel,

Fig. 2

eine axiale Schnittansicht einer erfindungsgemäßen Vorrichtung gemäß einem zweiten Ausführungsbeispiel,

Fig. 3

eine axiale Schnittansicht der erfindungsgemäßen Vorrichtung gemäß einem dritten Ausführungsbeispiel,

Fig. 4

Wandungssegmente und Außensegmente in einer Schnittansicht in Umfangsrichtung gemäß einem vierten Ausführungsbeispiel der erfindungsgemäßen Vorrichtung, und

Fig. 5

Wandungssegmente und Außensegmente in einer Schnittansicht in Umfangsrichtung gemäß einem fünften Ausführungsbeispiel der erfindungsgemäßen Vorrichtung.

In the following four embodiments of the invention will be explained in more detail with reference to four figures. Show it:

Fig. 1

an axial sectional view of a device according to the invention according to a first embodiment,

Fig. 2

an axial sectional view of a device according to the invention according to a second embodiment,

Fig. 3

an axial sectional view of the device according to the invention according to a third embodiment,

Fig. 4

Wall segments and outer segments in a sectional view in the circumferential direction according to a fourth embodiment of the device according to the invention, and

Fig. 5

Wall segments and outer segments in a sectional view in the circumferential direction according to a fifth embodiment of the device according to the invention.

Fig. 1 . 2 and 3 show a device 1 according to the invention for an otherwise merely indicated gas turbine, wherein the Fig. 1 a first embodiment, the Fig. 2 a second embodiment and Fig. 3 represent a third embodiment. The device 1 comprises Wandungssegmente 2, which are arranged in a circumferential direction U and outer segments 3, which are also arranged in the circumferential direction U and each attached to the radially outer surface 6 of an associated Wandungssegments 2.

In the exemplary embodiments shown here, the wall segments 2 form a wall or annular wall which bounds a hot gas duct of the turbomachine radially on the outside. The outer segments 3 are here heat shields to radially outer Gehäuseabschnittte 7 and other components of the turbomachine to protect against temperatures in the hot gas duct. The heat shields have a dual functionality, namely the protection of radially outer gas turbine components from hot gas channel side heat radiation and the other structural stiffening of the wall of the hot gas channel.

Each wall segment 2 has a first cross-sectional contour which is uniformly curved in the circumferential direction U. The shape of the first cross-sectional contour corresponds to a ring segment in the geometric sense. The wall segments 2, each with a front section 15 viewed in the flow direction, abut against a peripheral, radially outer housing surface 16 of a front receptacle. A rear section of the wall segments 2 bears against a circumferential, radially inner housing surface 17 of a rear receptacle of a housing section 18 which is adjacent to the housing section 7. In addition, each Wandungssegment 2 has a rear radially outwardly extending end portion 19 with which it rests against the housing portion 7 and is partially with this in radial overlap.

Each outer segment 3 is designed as a molded part and has countersinks 4 and elevations 5. In particular, each outer segment 3 is substantially sinusoidal in cross-section in an axial direction A of the gas turbine. In the circumferential direction U of the gas turbine, each outer segment 3 in cross section is also substantially sinusoidal (see also Fig. 4 and 5 ). The sinusoidal design is an example of a second cross-sectional contour. An imaginary envelope of an outer segment 3 including depressions 4 and / or elevations 5 forms the basic shape of the outer segment 3. However, any other geometric shapes for the depressions 4 and the elevations 5 can be selected. In addition, each outer segment 3 can be designed as a thin sheet.

The countersinks 4 of the outer segment 3 and the outer surface 6 of the associated Wandungssegments 2 form contact points 13, which allow attachment. The depressions 4 and the outer surface 6 of the Wandungssegments 2 are welded together at the contact points 13 or soldered together. The contact points 13 should be as small as possible so that the heat conduction from the wall segment 2 to the outer segment 3 is minimized. The outer segment 3 thus forms due to the fixed connections at the contact points 13, a gain of the associated Wandungssegments 2. As a result, the number of Wandungssegmente 2 is equal to the number of outer segments 3 (see also Fig. 3 and 4 ). However, not all depressions 4 must be firmly connected to the radially outer surface 6 of the wall segments 2. The number of fixed contact points 13 is variable. However, it is a sufficient stiffening of the wall segments 2 to ensure.

The spaces between the elevations 5 of the outer segments and the outer surface 6 of the Wandungssegmente 2 allow a flow of cooling air.

Each outer segment 3 is here associated with a spring element 8, which may be designed as a thin sheet metal. Each spring element 8 is fixedly connected to an associated outer segment 3.

Each spring element 8 is adapted to the geometric shape of the associated outer segment 3, that is, each spring element 8 also has the second cross-sectional contour. It is thus in this specific embodiment in the circumferential direction U of the gas turbine in cross section also sinusoidal and provided with not shown depressions and / or elevations. The spring element 8 is in the Fig. 1 . 2 and 3 shown in a relaxed state, however, it presses in operation, the associated outer segment 3 in the direction of the associated Wandungssegments 2. This also contributes to the high pressure that rests on the outside of the outer segment 3.

According to Fig. 2 In the second embodiment, the device 1 differs from the first embodiment according to one Fig. 1 in the flow direction, the outer segments 3 have a front spring portion 23 which is supported on a radially outer housing projection 20 of the front receptacle and thus act on the Wandungssegmente 2 in its front region with a radially inwardly directed force.

On the other hand, the device 1 differs in the second embodiment Fig. 2 from the first embodiment according to Fig. 1 in that the outer segments 3 each have a rear hook section 21 viewed in the flow direction, which is clamped together with the radially outwardly pointing end section 19 of the wall segment 2 between the housing section 7 and an axial projection 22 of the adjacent housing section 18.

According to Fig. 3 The device 1 differs in the third embodiment thereof from the first embodiment according to Fig. 1 in that a cover element 9 is attached to the outer circumference of each outer segment 3. The cover element 9 can be designed as a sheet metal and causes an even greater stiffening effect on an associated Wandungssegment 2 as the attachment of an associated outer segment 3 alone. The cover element 9 is fastened to the elevations 5 of the associated outer segment 3, for example by welding or soldering. The spring element 8 is attached to the cover element 9.

In the Fig. 4 and 5 the wall segments 2 and the outer segments 3 are shown in sectional views in the circumferential direction U. Between each two adjacent wall segments 2 is an inner gap 10. Between each two adjacent outer segments 3 is an outer gap 11. The outer segments 3 have here the same circumferential length as the Wandungssegmente second

In Fig. 4 are each an inner gap 10 and an outer gap 11 opposite. Depending on an inner gap 10 and an outer gap 11 are surmounted by a sealing element 14 (engl .: shiplap). Each sealing element 14 is fastened to an outer segment 3 and extends over a part of an adjacent outer segment 3.

In Fig. 5 the inner column 10 and the outer column 1 are each offset from each other, ie each outer segment 3 projects beyond an inner gap 10. Therefore, in contrast to the example in FIG Fig. 4 , no separate sealing elements required. The sinusoidal shape of each outer segment 3 thus extends in the circumferential direction U beyond an associated inner gap 10. It should be mentioned that in principle a "profiled" overlap is possible. That is, the outer segments 3 run in the circumferential direction U via an associated inner gap 10th in addition and have a side portion which is corresponding to the cross-sectional contour of the respective adjacent outer segment 3 in the overlapping region.

The first embodiment according to Fig. 1 , the second embodiment according to Fig. 2 and the third embodiment according to Fig. 3 can in the circumferential direction U in each case the fourth embodiment according to Fig. 4 and the fifth embodiment according to Fig. 5 and the non-illustrated embodiment of the "profiled overlap" mentioned in the preceding paragraph.

The production of an outer segment 3 can take place in such a way that a flat sheet passes through a series of pairs of rolls for the cold forming of sheets, so that initially a sheet with a uniformly curved cross-sectional contour is formed. The last pair of rollers has a shape which is complementary to the counterbores 4 and the elevations 5 of the outer segment 3 and thus forms the counterbores 4 and the elevations 5 in the outer segment 3.

The invention relates to a device for defining a flow channel of a turbomachine, having a wall which has a plurality of wall segments viewed in the circumferential direction of the turbomachine, and having a plurality of outer segments which radially surround the wall segments, wherein each wall segment a uniformly curved first cross-sectional contour, wherein each outer segment comprises at least one second cross-sectional contour which deviates from the uniformly curved first cross-sectional contour, wherein the second cross-sectional contour has a plurality of depressions, which are directed in the radial direction of the gas turbine inwardly and of which at least a part of the radially outer surface of an associated Wandungssegments is attached.

LIST OF REFERENCE NUMBERS

1

contraption

2

wall segment

3

outer segment

4

reduction

5

survey

6

Outer surface

7

housing section

8th

spring element

9

cover element

10

Inner cleft

11

Outer split

13

contact point

14

sealing element

15

Front section

16

Front housing surface

17

Rear housing surface

18

housing section

19

end

20

housing projection

21

hook section

22

axial projection

23

spring section

U

circumferentially

A

Axial direction

Claims (10)

Device (1) for limiting a flow channel of a turbomachine, having a wall which, viewed in the circumferential direction (U) of the turbomachine, a plurality of Wandungssegmenten (2), and having a plurality of outer segments (3), the Wandungssegmente (2) radially encompassing each other on the outside, wherein each wall segment (2) has a uniformly curved first cross-sectional contour, characterized in that each outer segment (3) comprises at least one second cross-sectional contour which deviates from the uniformly curved first cross-sectional contour, the second cross-sectional contour having a multiplicity of countersinks (4 ) directed inward in the radial direction of the gas turbine and at least part of which is fixed to the radially outer surface (6) of an associated wall segment (2). Device (1) according to claim 1, characterized in that the second cross-sectional contour in addition to the plurality of counterbores (4) comprises a plurality of protrusions (5). Device (1) according to claim 1 or 2, characterized in that the circumferential length of an outer segment (3) is equal to the circumferential length of an associated Wandungssegments (2) and depending on an outer gap (11) between two outer segments (3) and an inner gap ( 10) between two wall segments (2) face each other in the radial direction. Device (1) according to claim 3, characterized in that on each outer segment (3) a sealing element (14) is mounted, which covers an associated outer gap (11). Device (1) according to claim 1 or 2, characterized in that the circumferential length of an outer segment (3) is equal to the circumferential length of an associated Wandungssegments (2) and the outer segments (3) relative to the Wandungssegmenten (2) in the circumferential direction (U) of the gas turbine offset from one another. Device (1) according to one of the preceding claims, characterized in that on each outer segment (3) a spring element (8) for supporting on a housing portion (7) of the turbomachine is arranged. Device (1) according to one of the preceding claims, characterized in that at least one cover element (9) in the circumferential direction of the turbomachine on the outer segment (3) is fixed, wherein the cover element (9) in particular at elevations (5) of the second cross-sectional structure of the outer segment (3) is attached. Device (1) according to claim 7, characterized in that the cover element (9) has a uniformly curved first cross-sectional contour. Jet engine with a device (1) according to one of claims 1 to 8. Stationary gas turbine with a device (1) according to one of claims 1 to 8.

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