EP2650483A1 - Rotor blade and turbo-machine - Google Patents

Abstract

The rotor blade (4) has an inner cover band (24) which comprises a front extension (34) for forming an axial overlapping with an upcurrent guide blade (2). A flow guiding element (38) is arranged at the inner cover band for diverting a leakage flow (36) of a cooling air stream in the circumferential direction. The flow guiding element is guided out over a leading edge (40) of the extension in the axial direction. The flow guiding element terminates with a hot-gas side (42) and with a cooling-air side (44) of the extension.

Description

The invention relates to a blade for a turbomachine according to the preamble of patent claim 1 and a turbomachine.

It is generally known in engine construction that the turbine efficiency can be increased if a leakage flow of a, for example, the compressor side branched cooling air flow between the guide and blades is introduced into a hot gas flow. Such an introduction is, for example, in the patent US 7,244,104 B2 described. The patent proposes to arrange a plurality of flow directors in the form of ribs or depressions on an upstream extension of a blade inner shroud to form an axial overlap with an upstream stator blade. The flow guide elements are arranged on the hot gas side of the extension and have a front bow portion and a rear hot gas side axial portion. The arcuate portions extending in an axial direction away from a leading edge of the extension and passing into the axial portions are oriented in the direction of rotation. As a result, the flow guide elements are intended to scoop the leakage flow from a foot-side cavity of the guide vanes into the hot gas flow, as it were, and to act on the leakage flow at a peripheral speed which approximately corresponds to the peripheral speed of the inner cover strip. Fundamentally problematic in this case, however, is how the leakage current can be impressed on the peripheral speed, without causing a Heizgaseinzugs done in the foot-side cavity, which could lead to overheating of the guide and blades in the foot.

The object of the invention is to provide a blade which enables an optimized introduction of a leakage flow into a hot gas flow and effectively prevents a Heizgaseinzug, and to provide a turbomachine with improved efficiency.

This object is achieved by a blade for a turbomachine having the features of patent claim 1 and by a turbomachine having the features of patent claim 11.

A blade for a turbomachine according to the invention, in particular an aircraft engine, has an inner shroud with a front extension for forming an axial overlap with an upstream guide vane on which at least one flow guide for deflecting a leakage flow of a cooling air flow in the circumferential direction is arranged. According to the invention, the at least one flow-guiding element is led out in the axial direction beyond a front edge of the extension.

By the at least one guided over the front edge in the axial direction out flow guide the leakage current is prematurely imparted a velocity in the circumferential direction and thus in the direction of rotation of the blade. The leakage flow is introduced with a twist in a hot gas flow, whereby the introduction of the leakage flow is improved. A hot gas intake from the hot gas flow in the direction of the cooling air flow is effectively prevented. Preferably, the at least one flow-guiding element is formed integrally with the extension. The at least one flow guide can be rectilinear, arcuate, wave-like or similar. It should be noted that, due to thermal expansions, the flow guide element does not run onto an axially opposite guide blade section, so that an axial distance between the leading edge and the axially opposite guide blade section may be required to increase.

In one embodiment, the at least one flow guide is flush with a hot gas side and with a cooling air side of the extension. As a result, the at least one flow-guiding element is formed quasi as an axial finger. In a plurality of flow guide elements, the leading edge has a comb-like shape. The finger-like design has the advantage that the extension is not thickened by the at least one flow guide in the radial direction, but has a radial thickness which has its original thickness or height. An existing radial diaphragm gap is thus not reduced by the at least one flow guide and thus does not need to be readjusted.

In an alternative embodiment, the flow guide protrudes beyond the hot gas side and the cooling air side in the radial direction. As a result, the at least one flow guide element has a paddle-like shape. This embodiment has over the aforementioned finger-shaped embodiment has the advantage that an effective area of the flow guide is increased. However, constructive changes to the radial gap position may be necessary for the realization of this paddle-like flow element, in order to prevent the at least one flow guide element from running into adjacent radial guide blade sections or components due to thermal expansion in the radial direction.

In a further embodiment, the at least one flow guide element has a hot gas side section, which is guided on the hot gas side. The flow guide is thus extended on the hot gas side in a direction away from the front edge. As a result, the aerodynamic effect of the flow guide can be further enhanced. Depending on the position of the hot gas side portion in the axial direction of the leakage current can be accelerated to a speed in the circumferential direction, which is greater than the peripheral speed of the inner shroud, so as to ensure that the leakage current no speed is less than or significantly less than the peripheral speed impressed. At the same time, the extension of the at least one flow-guiding element to the extension effects structural-mechanical stabilization of the extension, so that they are reduced in cross-section, and thus optimized in weight, at least in the region of the flow-guiding element can. The at least one flow guide of this embodiment thus also acts as a stiffening structure in the form of a rib. Since the at least one rib-like flow-guiding element at least partially radially thickening the extension on the outside, structural changes may be necessary for the radial gap holding, which compensate for the reduced original radial distance. For example, it may be necessary to offset the extension to the radial gap attitude radially inward.

In a further embodiment, the at least one flow-guiding element has a cooling-air-side section which is guided on the cooling-air side. As a result, the leakage current is already applied in the region of the cooling air side with a swirl. To accelerate the leakage flow to a speed in the circumferential direction, which is greater than the peripheral speed of the inner shroud, the at least one cool air side rib-like flow guide opposite to the aforementioned hot gas side rib-like flow guide in the axial direction. Since the at least one rib-like flow guide element thickened the extension at least in sections radially inward, structural changes may be necessary for the radial clearance.

In one embodiment, the at least one flow guide has a hot gas side portion and a cool air side portion. Such a U-shaped flow guiding element has the advantage that the leakage flow is influenced on the cooling air side, on the front edge side and on the hot gas side by the at least one flow guiding element.

Preferably, the hot-gas-side portion and the cool-air-side portion are set opposite to each other when viewed in the direction of rotation. As a result, the leakage flow is subjected to a cooling air side and hot gas side with a rectified velocity component. In particular, viewed against the direction of rotation of the hot gas side portion is arranged in front of the cooling air side portion.

In particular, for structural mechanical and manufacturing reasons, it may be advantageous if the hot gas side section and / or the cooling air side section is performed over the entire length of the extension / are. Thus, it is possible to form the extension due to the stabilizing effect of at least one flow guide at least partially thin and thus weight-optimized, whereby the rotor mass can be reduced.

From a radial gap perspective view, it may be advantageous if the hot gas side and / or the cool air side section run parallel or substantially parallel to the respective radially opposite vane section or component. It is therefore preferred if the hot gas side and / or the cool air side section has / have a constant height. However, the height of the at least one flow-guiding element can also vary. Then, however, it will not be negative to the release effect of the diaphragm gaps to be influenced, preferably, when the at least one flow guide is formed flat beyond the front edge.

The swirling action or aerodynamic effect of the leakage flow can additionally be influenced by the number of flow guiding elements per extension. Thus, in one embodiment, a plurality of flow guide elements are arranged side by side, viewed in the circumferential direction, on an extension.

A preferred turbomachine has at least one blade row with a plurality of the blades according to the invention. Such a turbomachine is characterized by an improved efficiency over a turbomachine with conventional blade rows. Significant structural changes to adjacent to this blade row components such as vane rows and systems are not required. Depending on the design of the flow guide only minor structural changes to the gap position or to adjust the diaphragm gaps are necessary.

Other advantageous embodiments of the invention are the subject of further subclaims.

Figur 1

ein erfindungsgemäßes fingerförmiges Strömungsleitelements einer Laufschaufel,

Figur 2

ein paddelartiges Strömungsleitelements,

Figur 3

beispielhafte weitere Ausführungsbeispiele des erfindungsgemäßen Strömungsleitelements,

Figur 4

ein weiteres paddelartiges Strömungsleitelements,

Figur 5

ein Strömungsleitelement mit einem heißgasseitigen Abschnitt,

Figur 6

ein Strömungsleitelement mit einem kühlluftseitigen Abschnitt, und

Figur 7

ein Strömungsleitelement mit einem heißgasseitigen und einem kühlluftseitigen Abschnitt.

In the following, preferred embodiments of the invention will be explained in more detail with reference to highly simplified schematic illustrations. Show it:

FIG. 1

an inventive finger-shaped flow guide of a blade,

FIG. 2

a paddle-like flow guide,

FIG. 3

exemplary further embodiments of the flow guide according to the invention,

FIG. 4

another paddle-like flow guide,

FIG. 5

a flow guide with a hot gas side section,

FIG. 6

a flow guide with a cooling air side section, and

FIG. 7

a flow guide with a hot gas side and a cool air side section.

FIG. 1 shows an axial section through a turbomachine 1 in the region of a guide vane 2 and a downstream blade 4. The turbomachine is preferably an aircraft engine, but may also be a stationary gas turbine. The guide blade 2 is attached at the foot end to a housing section or guide blade support ring, not shown, and forms a fixed guide blade row with a plurality of further guide vanes 2, which surrounds a rotor hub (not shown) rotating about a rotation axis 6. The blade 4 is the foot side, for example. Via a disc element, connected to the rotor hub and forms with a plurality of other blades 4 with the rotor hub about the rotation axis 6 rotating blade row. A direction of rotation or circumferential direction is indicated by the arrow designated by the reference u.

The vane 2 has a platform 8 extending from an airfoil tip 10 and forming a radially inner boundary of a hot gas path. The hot gas path is flowed through by a hot gas flow 12 axially (x-direction). In the exemplary embodiment shown, the hot gas flow flows through the turbomachine 1 from left to right. To stabilize the platform 8, this has a plurality of webs 14, which are arranged on a side facing away from the blade tip 10 page. With sufficient inherent stability of the platform 8, however, the webs can be omitted.

From the platform 8 extends a radially inwardly directed mounting flange 16 for attachment of the vane 2 to a rotor hub encompassing fixed connecting ring (not shown). The mounting flange 16 is spaced from a rear edge 18 of the platform 8 and limited to the platform 8 an annular space 20. On the mounting flange 16 a peripheral plate 22 is connected, which limits the annular space 20 in the direction of the rotor hub and thus the annular space 20 in a radially outer Cavity and divided into a radially inner cavity.

The blade 4 has an in-deck belt 24 disposed between a blade neck 26 and blade shroud and an airfoil 28, respectively, and defining an inner radial boundary of the hot gas path. It is in the embodiment shown approximately at the same radial position as the platform 8. The blade 4 and the guide blade 2 are arranged in the axial direction to each other such that between the trailing edge 18 of the platform 8 and an outer end face 30 of the inner cover tape 24 a Annular gap 32 is formed through which in principle a gas exchange between the hot gas flow 12 and a hub-side cooling air flow (not shown) can take place. For almost complete structural sealing of the annular gap 32 in the radial direction (y-direction), the inner cover tape 24 has a front extension 34 for forming an axial overlap with the guide vane 2 or with its platform 8. The extension 34 extends from the outer end surface 30 in the direction of the vane 2 and has a length such that it dips into the annular space 20 and the outer cavity between the platform 8 and the peripheral plate 22.

To avoid a hot gas intake, a leakage flow 36 of the cooling air flow is blown into the hot gas flow 12 through the annular gap 32. According to the invention is for introducing the leakage current 36 with a twist in the hot gas flow 12 or for impressing the peripheral speed of the inner cover tape 24 on the leakage flow 36 at least one flow guide 38 is provided. At the same time, the machine efficiency is improved by the swirl-induced introduction of the leakage flow 36 into the hot gas flow.

In the in FIG. 1 As shown in the first embodiment, the flow guide 38 is formed as a finger-shaped projection extending substantially in the axial direction from a front edge 40 of the front extension 34. The projection or the flow guide element 38 is preferably rectilinear, but may also be concave in the circumferential direction u, for example. In a plurality of such finger-shaped projections 38, the front edge 40 has a comb-like shape. Preferably, the flow guiding element 38 merges flush into a hot gas side 42 and into a cooling air side 44 of the front extension 34. Thus, in this embodiment, it has the same radial extent as the front extension 34, so that the flow guide element 38 does not affect a radial diaphragm gap between the extension 34 and the web 14 and between the extension 34 and the peripheral sheet 22. Depending on the axial extension of the at least one flow guide element 38 beyond the front edge 38, an original axial distance between the front edge 38 and the fastening flange is to be increased for axial gap holding.

At an in FIG. 2 In the embodiment shown, the flow guiding element 38 is designed as a front edge-side projection, which is led out in the radial direction via the hot gas side 42 and via the cooling air side 44. As a result, this flow guide 38 has a paddle-like and in particular a crescent-like shape. In particular, the flow guide 38 has flat outer surfaces. Preferably, the flow guide 38 is not employed in the axial direction x and in the radial direction y (axial angle of attack and radial angle of attack = 0 °). However, it can also be employed in the axial direction x and / or in the radial direction y (axial angle of attack and / or radial angle of attack ≠ 0 °).

Due to the radial extension of the flow guide 38 over the hot gas side 42 and the cooling air side 44 addition, the at least one flow guide 38 after FIG. 2 an opposite to the preceding finger-shaped embodiment according to FIG. 1 Increased effective area for swirling the leakage flow 36. For radial gap holding or to prevent emergence of the flow guide 38 on the web 14 and the peripheral sheet due to thermal expansion, it may be necessary, the extension 34 and the peripheral plate 22 relative to the finger-like embodiment FIG. 1 radially inwardly (not shown). Since the at least one flow guide element 38 also extends in the direction of the peripheral plate 22, the peripheral plate 22 is then displaced radially inwards in the case of axially symmetrical design of the flow guide element 38 in comparison to the extension 34 by two times.

In FIG. 3 Further embodiments of the flow guide 38 are outlined. These have in contrast to the aforementioned embodiments of the Figures 1 and 2 in addition, a rib-like extension in the direction of a blade neck 26 and a radially outer end surface 30 and a radially inner end surface 46 of the blade neck 26. Insofar, these flow guide 38 have a projecting in the axial direction x over a front edge 40 head portion 48 and a from the head portion in Direction of the blade neck 26 extending hot gas side portion 50 and / or a cold gas side portion 52. The sections 50, 52 may extend as indicated by the dashed lines only over a length range of the extension 34 or pass into the end surfaces 30, 46.

If the sections 50, 52 are guided over only a length range of the extension 34, it is preferred for reasons of structural mechanics if these pass continuously, eg in a ramp-like manner, into the hot gas side 42 or cooling air side 44. When the portions 50, 52 extend to the blade neck 26, it is preferred that they have a constant height in the radial direction. By the portions 50, 52, the effective area of the at least one flow guide element 38 in comparison to the second embodiment after FIG. 2 further increased, which has a positive effect on the swirling action of the leakage flow 36. In addition, the flow guide 38 by the embrace of the front edge 40 in contrast to the previous embodiments of the Figures 1 and 2 stabilized.

In FIG. 4 an embodiment of the flow guide 38 is shown with a hot gas side portion 50 and with a cool air side portion 52 which extend only over a length range of an extension 34. The flow guide element 38 surrounds a front edge 34 in a U-shape and merges steplessly into a hot gas side 42 and into a cooling air side 44. For example, the flow guide 38 in side view, a flat circular disc, which is interrupted in the hot gas side 42 and the cooling air side 44 by the extension 34. Thus, this paddle-like flow guide 38 has a full moon-like shape with a head portion 48 and two quasi-Auslaufabschnitten 50, 52. Due to the extension of the flow guide 38 on the hot gas side 42 and the cooling air side 44 of this embodiment has the same extent in the radial direction a larger effective area than the embodiment according to FIG. 2 ,

Preferably, the at least one flow guide element 38 is not employed in the axial direction x and in the radial direction y. However, it can also be set in the axial direction x or in the radial direction y or inclined positively or negatively. For radial gap holding the extension 34 and a peripheral plate 22 analogous to the embodiment according to FIG. 2 offset radially inward.

In FIG. 5 an embodiment of a rib-like flow guide 38 is shown, which in axial direction x extends beyond a front edge 40 of an extension 34 addition, wherein it is flush with its head portion 48 flush with a cooling air side 44 and is guided with its hot gas side portion 50 to the outer end surface 30. As a result, this flow guide 38 has an L-shaped design in side view.

The hot gas side portion 50 preferably has an elongated rectilinear shape with a constant height. He is employed on a hot gas side 44 of the extension 34 in the axial direction x. The head section 48 is preferably not set in the axial direction x.

The inclination of the hot gas side portion 50 is in this embodiment such that viewed against the direction of rotation u considered the hot gas side portions 50 in front of the head portion 48. The hot gas side section 50 thus exits the drawing plane starting from the head section 48. As a result of the inclination, the leakage flow 36 as it exits the outer cavity is accelerated to a speed in the circumferential direction u which is equal to or slightly greater than the peripheral speed of the inner cover tape 24.

For radial gap maintenance or to prevent run-up of the flow guide 38 on the web 14 and the peripheral plate 22 due to thermal expansion, if necessary, the extension 34 and a peripheral plate 22 relative to the finger-shaped embodiment according to FIG. 1 be radially inwardly offset (not shown). Since the at least one rib-like flow guide element 38 is arranged on the front edge side and on the hot gas side and thus an original radial distance between the extension 34 and the peripheral plate 22 is not reduced, then the peripheral plate 22 can be displaced radially inward by the same radial path as the extension 34.

In FIG. 6 an embodiment of a rib-like flow guide 38 is shown extending in the axial direction x beyond a front edge 40 of an extension 34, wherein it is flush with its head portion 48 with a hot gas side 42 and is guided with its cooling air side portion 52 to the inner end surface 46 , As a result, this flow guide 38 in side view also has an L-shaped configuration.

The cool air side portion 52 preferably has a constant height and is formed in a straight line. He is employed on a hot gas side 44 of the extension 34 in the axial direction x. The head section 48 is preferably not set in the axial direction x.

To accelerate the leakage flow 36 to a speed which is approximately or slightly greater than the peripheral speed of the inner shroud 24, the inclination of the cool air side portion 52 in this embodiment is such that viewed against the rotational direction of the cool air side portion 52 is disposed behind the head portion 48 is. The cool air side portion 52 Thus, starting from the head section 48, it enters the plane of the drawing.

For radial clearance, if necessary, a peripheral plate 22 relative to the finger-shaped embodiment according to FIG. 1 be radially inwardly offset (not shown). Since the at least one rib-like flow guide element 38 is arranged on the front edge side and the cool air side, and thus an original radial distance between the extension 34 and the web 14 is not reduced, the extension 34 does not have to be radially offset inwards.

In FIG. 7 is a plan view of a developed circumferential portion of a blade row in the region of a front extension 34 is shown, which is provided with a further embodiment of the flow guide element 38 according to the invention. As shown in FIG. 3 surrounds the flow guide 38 with its head portion 48 on both sides of a front edge 40 of the extension 34 and is guided with a hot gas side portion 50 and with a cooling air side portion 52 to the outer and inner end surface 30, 46. The sections 50, 52 preferably have a uniform constant height and are rectilinear. They are obliquely set in the axial direction x and in particular oriented towards each other so that they extend diagonally opposite from the head portion 48 in the direction of the end surfaces 30, 46. The head section 48 is preferably not set in the axial direction x.

The inclination of the sections 50, 52 in this embodiment is such that, viewed counter to the direction of rotation u, the hot-gas-side section 50 is arranged in front of the cooling-air-side section 52. The hot gas side portion 50 thus emerges from the drawing plane from the head portion 48, and the cool air side portion 52 enters the drawing plane from the head portion 48. Thus, this flow guide 38 in side view has a rib-like and in particular V-shaped configuration with two mutually pivoted fork sections 50, 52nd

Disclosed are a blade for a turbomachine, in particular an aircraft engine, with a Inndeckband having a front extension for forming an axial overlap with an upstream vane and on which at least one flow guide for deflecting a leakage flow of a cooling air flow in the circumferential direction is arranged, the at least a flow guide is led out beyond a front edge of the extension, and a turbomachine with a plurality of such blades.

LIST OF REFERENCE NUMBERS

1 flow machine 2 vane 4 blade 6 axis of rotation 8th platform 10 Airfoil tip 12 Hot gas flow 14 web 16 mounting flange 18 trailing edge 20 annulus 22 extensive sheet 24 Inner shroud 26 scoop-neck 28 airfoil 30 outer face 32 annular gap 34 front extension 36 leakage current 38 flow guide 40 leading edge 42 Hot gas side 44 Cooling air side 46 inner face 48 header 50 Hot gas side section 52 Cooling-air-side section x axial direction y radial direction u Circumferential direction or rotation direction

Claims (11)

Blade (4) for a turbomachine (1), in particular an aircraft engine, with an in-deck belt (24) having a front extension (34) for axial overlap with an upstream stator (2) and at least one flow-directing element (38 ) for deflecting a leakage flow (36) of a cooling air flow (36) in the circumferential direction (u) is arranged, characterized in that the at least one flow guide (38) via a front edge (40) of the extension (34) in the axial direction (x) out is. The blade of claim 1, wherein the flow directing element (38) is flush with a hot gas side (42) and with a cooling air side (44) of the extension (34). A blade according to claim 1, wherein the flow guide (38) projects beyond the hot gas side (42) and the cooling air side (44) in the radial direction (y). The moving blade according to claim 1, wherein the flow guide (38) has a hot gas side portion (50) guided on the hot gas side (42). The moving blade according to claim 1, wherein the flow guide member (38) has a cool air side portion (52) guided on the cooling air side (44). A moving blade according to claim 1, wherein the flow guide member (38) has a hot gas side portion (50) guided on the hot gas side (42) and a cool air side portion (52) guided on the cooling air side (44). The moving blade according to claim 6, wherein the hot gas side portion (50) and the cool air side portion (52) are oriented opposite to each other in the rotational direction (u). The moving blade according to any one of claims 4 to 7, wherein the hot gas side portion (50) and / or the cool air side portion (52) is guided over the entire axial extent of the extension (34). A blade according to any one of claims 4 to 8, wherein the hot gas side portion (50) and / or the cool air side portion (52) has a constant height. The blade of any one of the preceding claims, wherein the extension (34) is provided with a plurality of flow directors (38). Turbomachine (1) with a blade row with a plurality of blades (4) according to one of the preceding claims.

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