EP2460979B1 - Blade segment of a flow engine with radial support surfaces - Google Patents

Description

The present invention relates to a blade segment and a turbomachine.

For example, it is from the document JP 2007154695 A known to torsionally bias turbine blades. This has a favorable effect on the operation of the turbine blades with respect to a damping behavior thereof. The Torsionsvorspannung is maintained by the fact that the turbine blades each have shrouds at their blade tips, which are clamped together via a Z-latching. This Z-latching is also called "Z-shroud".

The object of the present invention is to provide an alternative or complementary approach, which provides a coupling between at least two blades of a blade segment in order to achieve a favorable damping behavior.

This object is achieved by a blade segment having features of patent claim 1 and by a turbomachine having the feature of claim 10.

Accordingly, a vane segment for a turbomachine comprising: a first vane; a first shroud connected to the tip of the first blade and having a bearing surface; a second blade; and a second, connected to the tip of the second blade second shroud, which has a counter-contact surface for a concern of the contact surface of the first shroud in the radial direction such that a frictional engagement between the contact surface and the counter-contact surface can be generated; provided.

Furthermore, a turbomachine, in particular turbomachine, is provided with the blade segment according to the invention.

The idea underlying the present invention is to arrange the shrouds of the respective blades like a roof tile, so that the shrouds in the radial direction against each other so that at least during operation of the blade segment (or even at a standstill) formed a frictional engagement between overlapping shrouds becomes. The frictional engagement ensures a coupling of the shrouds or the blades with each other, which is favorable in terms of a damping behavior.

From the subclaims advantageous embodiments result.

The concern of the contact surface against the counter-contact surface in the radial direction is to be understood here that a vector perpendicular to the plane in which abut the abutment surface and the counter-contact surface against each other, has at least one radial component.

In this case, "circumferential direction" means a direction along a circular line which has the axis of rotation of the blade segment in the turbomachine as the central axis. In this case, "radial" refers to a direction perpendicular to the axis of rotation of the blade segment in the turbomachine. In the present case, "axial" refers to a direction along the axis of rotation of the blade segment in the turbomachine.

According to one embodiment of the blade segment according to the invention, the center of gravity of the first shroud is circumferentially spaced from a central axis of the first blade so that the first blade flexes under the action of the centrifugal forces during operation of the blade segment to produce the frictional engagement between the abutment surface and the opposing abutment surface. During operation of the blade segment, a bending moment thus arises under the action of the centrifugal forces which tends to tip the blade together with the shroud in the circumferential direction. But this tilting is prevented by means of the contact surface of the first shroud and the counter-bearing surface of the second shroud. The contact surface presses in the radial direction against the counter-contact surface in such a way that frictional engagement occurs between the contact surface and the counter-contact surface.

By "central axis" herein is meant the axis of the first blade positioned such that, if the center of gravity of the first shroud were coincident therewith, no or only a negligible bending moment would be introduced from the shroud into the first blade. The same applies to the central axis of the second blade.

According to one embodiment of the blade segment according to the invention, the contact surface of the first shroud and / or the counter-bearing surface of the second shroud with a pressing dimension formed in the radial direction for bending the first blade about its base in the circumferential direction, thereby generating the frictional engagement between the abutment surface and the counter abutment surface. By a pressing dimension is meant that the contact surface and / or counter-contact surface is thickened in the radial direction, thereby generating a surface pressure and thus a frictional engagement between the contact surface and the counter-contact surface. This embodiment can be provided as an alternative or in addition to the previous embodiment, in which the center of gravity of the first shroud arranged in the circumferential direction of a central axis of the first blade so spaced.

According to a further embodiment of the blade segment according to the invention, the frictional engagement is designed to generate a torsional reaction torque in one direction about the central axis of the first and the second blade. This is favorable for compensating for the tendency to unwind of radially twisted blade profiles.

According to a further embodiment of the blade segment according to the invention, the first and / or second blade on a basic inclination in the axial direction, which is defined by a base inclination axis, wherein the contact surface and counter-bearing surface obliquely, in particular at an angle between 45 and 135 degrees, with respect Base pitch axis in the axial direction of the first and the second blade are arranged. The basic inclination is also called "lean". The basic inclination usually serves to largely compensate for the gas forces which occur during operation of the turbomachine and which generate corresponding bending moments on the blades, at least in certain operating regions of the turbomachine. The base inclination is usually between 0 and 2 degrees depending on the configuration of the turbomachine. The oblique arrangement of contact surface and counter-bearing surface causes a torsional moment about the central axis of a respective blade is created, which can counteract a unwinding of a respective blade. Here are two mirror-image arrangements possible. This torsional moment increases, the more the contact surface presses against the counter-contact surface.

According to a further embodiment of the blade segment according to the invention, the abutment surfaces and counter abutment surfaces on an engagement element and a receiving element, which engage in one another in the circumferential direction. As a result, the first and second shroud are even better, so in addition to the frictional engagement, supported each other. In particular, this embodiment prevents unwinding of the blades when no frictional engagement is generated (For example, at standstill of the blade segment in the embodiment with the offset in the circumferential direction center of gravity of the shroud).

According to a further embodiment of the blade segment according to the invention, the first and / or second blade is torsionsvorgespannt. If the blades engage with each other by means of the above-described engaging and receiving elements, it is possible, for example, to bias the blades torsionally so that sufficient coupling between the blades is achieved even at low rotational speeds, which brings about a favorable damping behavior. The frictional engagement due to the offset of the center of gravity of a respective shroud may not be sufficient at the low speeds to achieve such sufficient coupling between the shrouds.

According to a further embodiment of the blade segment according to the invention, the first and second blades are designed as moving blades.

According to a further embodiment of the blade segment according to the invention, the first and second blades are made of a strong creeping material. By "strong creeping materials" are meant those materials that crawl more than current nickel materials.

The invention will be explained in more detail by means of embodiments with reference to the accompanying figures of the drawings.

Figur 1

in axialer Richtung gesehen, schematisch ein Schaufelsegment gemäß einem Ausführungsbeispiel der vorliegenden Erfindung;

Figur 2

einen Schnitt A-A aus Figur 1,

Figur 3

einen Schnitt B-B aus Figur 1,

Figur 4

in einer perspektivischen Ansicht von schräg unten das Schaufelsegment gemäß Figur 1; und

Figur 5

in axialer Richtung gesehen, schematisch ein Schaufelsegment gemäß einem weiteren Ausführungsbeispiel der vorliegenden Erfindung;

Show it:

FIG. 1

seen in the axial direction, schematically a vane segment according to an embodiment of the present invention;

FIG. 2

a section AA FIG. 1 .

FIG. 3

a cut BB off FIG. 1 .

FIG. 4

in a perspective view obliquely from below the blade segment according to FIG. 1 ; and

FIG. 5

seen in the axial direction, schematically a vane segment according to another embodiment of the present invention;

In the figures, like reference numerals designate like or functionally identical components, unless indicated otherwise.

FIG. 1 As seen in the axial direction, schematically shows a blade segment 1 according to an embodiment of the present invention.

The blade segment 1 is part of a turbomachine, in particular a turbomachine, which is generally designated 2. The turbomachine is preferably an aircraft engine.

The blade segment 1 has two blades 3 and 3 'on the blades 3, 3' are preferably formed as blades. The blades 3, 3 'are with their respective feet 4, 4' in a rotor 5, see FIG. 4 , For example by means of a Christmas tree connection, attached. The rotor 5 rotates about an axis 6, wherein the blades 3, 3 'interact with a fluid flowing through the turbomachine 2. The terms "in the circumferential direction", "in the radial direction" and "in the axial direction" refer hereinafter to the axis 6. It should be noted that the axis 6 is located in reality much further away from the blades 3, 3 ', as in FIG. 1 shown.

At their tips, so radially outside, the blades 3, 3 'are each connected to shrouds 7, 7'. The blades 3, 3 ', together with their feet 4, 4' and shrouds 7, 7 'are arranged side by side in the circumferential direction U and preferably form a closed ring, wherein in FIG. 1 only a section with two of the blades 3, 3 'is shown. The shrouds 7, 7 'are arranged one above the other like a roof tile in the axial direction.

The shrouds 7, 7 'each have a center of gravity S, S', which has a distance D, D 'on a central axis M, M' of a respective blade 3, 3 '. The central axes M, M 'each extend through the axis 6, which due to the highly schematic representation in FIG. 1 is not recognizable. The central axis M extends through a center of gravity SB of the blade 3, see FIG. 2 , The center of gravity SB is the center of gravity of the profile of the blade 3. The same applies to the central axis M 'of the blade 3'.

A respective shroud 7, 7 'has a contact surface 11, 11' and a counter-contact surface 12, 12 'lying opposite it. The contact surfaces 11, 11 'and counter-contact surfaces 12, 12' may each be formed at the ends of the shrouds 7, 7 'in the circumferential direction U.

If the blade segment 1 has no or only a low rotational speed, no or almost no centrifugal forces act on the blades 3, 3 'together with their shrouds 7, 7'. The blades 3, 3 'together with shrouds 7, 7' are then in the in FIG. 1 only for the left blade 3 drawn in dashed line position. If the rotational speed of the blade segment 1 increases, a bending moment of the shroud 7 increases by a blade root F. This is because the center of gravity S has the distance D to the center line M or the center of gravity SB of the blade 3. The resulting bending moment is in FIG. 1 denoted by BM. The bending moment BM causes the blade 3 together with the shroud 7 from its dashed position in FIG. 1 in its position shown in a solid line tilts, ie bends. From a certain speed, the contact surface 11 comes into contact with the counter-contact surface 12 'in the radial direction R, that is to say that a vector 9, see FIG Fig. 3 , perpendicular to the plane 10, in which the contact surface 11 and the counter-bearing surface 12 'bear against each other, at least one component in the radial direction R has. This creates a frictional engagement between the contact surface 11 and the counter-contact surface 12 '. From this point on, the blade 3 is frictionally coupled to the blade 3 ', which has an advantageous effect with regard to a vibration behavior thereof.

FIG. 2 shows a section A-A from FIG. 1.

In FIG. 2 It can be seen that the frictional engagement RF between the abutment surface 11 and the counter-abutment surface 12 'may be formed to produce a torsional reaction torque TM about the center axis M, preventing the blade 3 from undesirably swinging about the central axis.

FIG. 3 shows a section B-B from FIG. 1.

As FIG. 3 can be found, the contact surface 11 and the counter-bearing surface 12 'with respect to a base inclination axis G' obliquely at an angle W 'of, for example, 93 degrees to be arranged. "Sloping" means an angle W 'other than 90 degrees and preferably between 45 and 135 Degree. The base inclination axis G 'of the blade 3' may be inclined for example by 1 degree in the direction of the axis of rotation 6.

Under the action of the centrifugal forces and a corresponding unwinding of the blade 3, a contact pressure AK results between the contact surface 11 and the counter-contact surface 12 '. Due to the oblique arrangement of the contact surface 11 and the counter-contact surface 12 ', the contact force AK results in a reaction force RK1 and a reaction force RK2, which act on the blade 3. RK2 acts along the base pitch axis G 'and RK1 perpendicular thereto.

RK1 is also in FIG. 2 shown. Here it can be seen that RK1 generates an additional torsional moment TR about the center of gravity SB or the center axis M of the blade 3, which counteracts a winding E of the blade 3.

FIG. 4 1 shows the vane segment FIG. 1 in a perspective view obliquely from below.

As in FIG. 4 illustrated, the shrouds 7, 7 'at their opposite ends preferably in the region of the contact surfaces 11, 11' and counter-bearing surfaces 12, 12 'engaging elements 13, 13' and receiving elements 14, 14 'on. The engagement element 13 'of the shroud 7' engages in the circumferential direction in the receiving element 14 of the shroud 7 a. This results in a form fit in the axial direction, which unwinding of the blades 3, 3 'at a standstill of the blade segment 1 or at low speeds, where the frictional engagement RF is still too low to couple the blades 3, 3' together prevented ,

Fig. 5 As seen in the axial direction, schematically shows a blade segment 1 according to another embodiment of the present invention.

The blade segment 1 differs from that according to the Fig. 1 to 4 only in the way the friction fit RF is generated. Incidentally, therefore, the comments on the Fig. 1 to 4 according to the blade segment Fig. 5 ,

At the blade segment 1 after Fig. 5 is the contact surface 11 of the shroud 7 with a pressing dimension P in the radial direction R for bending the first blade 3 about its base F formed in the circumferential direction U, thereby generating the frictional engagement RF between the abutment surface 11 and the counter-abutment surface 12 '. Of course, the same applies to the other blades of the blade segment.

The frictional engagement RF in the embodiment according to Fig. 5 is advantageous not or only slightly dependent on speed.

The embodiments according to the Fig. 1 to 4 and after Fig. 5 can also be combined with each other.

Although the invention has been described herein with reference to preferred embodiments, it is not limited thereto, but variously modifiable.

LIST OF REFERENCE NUMBERS

1

vane segment

2

flow machine

3

shovel

3 '

shovel

4

foot

4 '

foot

5

rotor

6

axis of rotation

7

shroud

7 '

shroud

9

vector

10

level

11

contact surface

11 '

contact surface

12

Anvil surface

12 '

Anvil surface

13

engaging member

13 '

engaging member

14

receiving element

14 '

receiving element

D

distance

F

nadir

G'

Basic tilt axis

M

central axis

M '

central axis

R

radial direction

S

main emphasis

S '

main emphasis

U

circumferentially

AK

contact force

BM

Bending moment

RF

friction force

RK1

reaction force

RK2

reaction force

SB

Shovel emphasis

TM

Torsionsreaktionsmoment

TR

torsional

e

unwinding

Claims (9)

1. Blade segment (1) for a turbomachine (2), having:

   a first blade (3);

   a first shroud (7) connected to a tip of the first blade (3), which shroud has a contact surface (11);

   a second blade (3'), wherein the first and second blade (3, 3') are formed as rotor blades; and

   a second, second shroud (7') connected to a tip of the second blade (3'), which shroud has a counter-contact surface (12') for an abutment of the contact surface (11) of the first shroud (7) in a radial direction (R) in such a way that a friction locking (RF) can be produced between the contact surface (11) and the counter-contact surface (12'),

   characterised in that the contact surface (11) and counter-contact surface (12') are arranged obliquely in the axial direction.
2. Blade segment according to claim 1, characterised in that the centre of mass (S) of the first shroud (7) is arranged at a distance in the circumferential direction (U) from a centre line (M) of the first blade (3) such that the first blade (3) bends under the influence of the centrifugal forces in operation of the blade segment (1) for the production of the friction locking (RF) between the contact surface (11) and the counter-contact surface (12').
3. Blade segment according to claim 1 or 2, characterised in that the contact surface (11) of the first shroud (7) and/or the counter-contact surface (12') of the second shroud (7') are formed with a pressing dimension (P) in the radial direction (R) for a bending of the first blade (3) about its root point (F) in the circumferential direction,(U), in order thereby to produce the friction locking (RF) between the contact surface (11) and the counter-contact surface (12').
4. Blade segment according to one of the preceding claims, characterised in that the friction locking (RF) is formed to produce a torsion reaction torque (TM) in a direction about the centre line (M) of the first and/or second blade (3).
5. Blade segment according to one of the preceding claims, characterised in that the first and/or second blade (3') have a basic inclination in the axial direction (6), which is defined by a basic inclination axis (G'), wherein the contact surface (11) and counter-contact surface (12') are arranged obliquely, in particular at an angle (W') between 45 and 135 degrees, in relation to the basic inclination axis (G') of the first and/or second blade (3').
6. Blade segment according to one of the preceding claims, characterised in that the contact surface (11) and counter-contact surface (12') have an engagement element (13') and a receiving element (14), which engage in one another in the circumferential direction (U).
7. Blade segment according to one of the preceding claims, characterised in that the first and/or second blade (3, 3') is torsion-pretensioned.
8. Blade segment according to one of the preceding claims, characterised in that the first and/or second blade (3, 3') is formed from a material that creeps more strongly than nickel materials.
9. Turbomachine (2) with a blade segment (1) according to one of the preceding claims.

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