EP3420199A1

EP3420199A1 - Turbine blade, associated device, turbomachine and use

Info

Publication number: EP3420199A1
Application number: EP17714667.7A
Authority: EP
Inventors: Ole Geisen; Christoph Haberland; Carl Hockley; Susanne Kamenzky; Thomas Lorenz; David Rule; Alexandr Sadovoy; Eva Scheu
Original assignee: Siemens AG
Current assignee: Siemens AG
Priority date: 2016-04-12
Filing date: 2017-03-22
Publication date: 2019-01-02
Also published as: CA3020425A1; WO2017178203A1; DE102016206022A1; US20190048737A1; CN109072708A

Abstract

The present invention relates to a turbine blade (10) for a turbomachine, comprising a blade airfoil (1) with a blade tip region (3) and a sealing region (2) which has an auxetic material and is arranged and designed such that, when transitioning from a rest state (10) to an operating state of the turbine blade (10), the blade tip region (3) of the turbine blade expands in a first direction (4) perpendicular to a longitudinal axis (A) of the blade airfoil (1). Also described is the use of an auxetic material for a turbine blade (10) for sealing a gas path during operation of a turbomachine.

Description

description

TURBINE BLADE, ASSEMBLY DEVICE, FLOW MACHINE AND USE The present invention relates to a turbine blade, such as a gas or steam turbine blade or a turbine compressor blade. Furthermore, the present invention relates to a device and a turbomachine and the use of a

auxetic material for the turbine blade.

Turbine blades are known, for example, from EP 0 991 866 B1. For efficient operation of turbomachines, it is important that a gap between a turbine blade, in particular the blade tip, and a surrounding ring segment is kept as small as possible during operation. Large gaps have correspondingly a negative influence on the efficiency of the turbine, since a working fluid, which flows past the bucket in operation, can not do "work" and thus, for example, remains unused for power generation However, certain gap spacings due to the thermal expansion of the blades and of the housing or ring segment, for example, in the transition from a rest state to an operating state of the turbine blade and / or the turbomachine inevitable.

Turbine blades usually heat up much faster when starting a turbomachine than the housing. Thus, the blades also expand before the housing expands due to its heating. As a result, gaps in the starting phase of the turbomachine usually have the smallest dimensions. If the housing heats up as a result, it also expands and the gap distances inevitably become larger again. The problem of large gaps between the blade tip and the ring segment has hitherto been encountered using abrasive materials, with a blade tip being able to grind into the ring segment during operation, for example. Alternatively, a shaft of the turbomachine together with blading can be displaced until the complete heating of all relevant components to the final operating temperature along an axis of rotation of the turbomachine (in gas turbines, for example, in the direction of the combustion chamber).

It is an object of the present invention to provide an improved or alternative solution to the problem described, in particular to keep a gap (radial gap) between a turbine blade and a surrounding housing as low as possible during operation of the turbomachine by an effective seal.

This object is solved by the subject matter of the independent claims. Advantageous embodiments are the subject of the dependent claims.

One aspect of the present application relates to a turbine blade for a turbomachine, in particular a turbine, comprising an airfoil with a blade tip area and a sealing area. The sealing region is provided in particular for sealing a path of a working fluid for the turbomachine.

Said path of the working fluid is expediently defined in an operating state of the turbomachine at least by the turbine blade and the housing or ring segment. The path is preferably a hot gas path, for example in the case of gas turbines as turbomachines.

The sealing region is arranged and configured in such a way that the blade tip region changes from an idle state of the turbine blade into an operating state during the transition from an idle state of the turbine blade Turbine blade expands in a first direction perpendicular to a longitudinal axis of the airfoil.

In one embodiment, the sealing region has an auxetic material. As a result of this embodiment, the above-mentioned extent can be achieved particularly expediently or even made possible in the first place. Said expansion is preferably a different extension from a normal thermal expansion along the first direction. In particular, the extent, which arises due to the auxetic behavior of the auxetic material or the sealing area in the transition to the operating state according to the invention, advantageously exceeds a corresponding thermal expansion along the first direction.

As a result of the expansion described, the turbine blade is preferably designed such that, in the operating state, a gap, which is preferably inherently located between the blade tip region and a stator, ring segment or housing of the turbine, is sealed as well as possible or optimally, so that advantageously approximately the entire flow of the working fluid is used - Fluids used in the operation of the turbine blade for power generation and the efficiency of the turbomachine can be improved.

Preferably, the "longitudinal axis" of the airfoil defines a direction or axis from a blade root to the blade tip region Describes preferably a state of the turbine blade and / or the turbomachine according to a normal operation, in which the turbine blade is preferably acted upon with a hot gas or steam as the working fluid.

The "resting state" preferably describes a state of the turbine blade in which it is not in an operating state.

In one embodiment, the sealing region is arranged and configured in such a way that the blade tip region additionally extends in a second direction, that is to say along the longitudinal axis of the blade, from the transition from the rest state into the operating state. This expansion may refer to the ordinary, initially mentioned thermal expansion of the blade tip region or, preferably, of the entire blade. Axial expansion (along the second direction) of the airfoil and / or the turbine blade is preferably caused by centrifugal forces and / or thermal expansion during a start-up operation or during operation.

The "first direction" may describe a direction along an axis of rotation of the turbomachine or a shaft thereof The first and second directions preferably respectively describe axes or dimensions along which the blade tip region correspondingly expands in opposite directions of expansion Direction, for example, two exactly opposite directions perpendicular to the longitudinal axis of the blade, preferably along the axis of rotation described.

In one embodiment, the sealing region comprises the blade tip region of the turbine blade. According to this embodiment, the expansion can be implemented particularly expediently as described above, since the sealing region, preferably containing the auxetic material, is arranged directly on the blade tip. In one embodiment, the sealing area is separate from

Blade tip region of the turbine blade arranged. In other words, the sealing area does not directly form the

Blade tip, but is preferably arranged next to it.

According to this embodiment, the blade tip area can advantageously serve as a traction mass and, via the auxetic behavior of the sealing area and a force, which preferably acts in the operating state of the turbine blade along the longitudinal axis of the blade, for example a centrifugal force, particularly expediently an extension in the first direction, i. perpendicular to the longitudinal axis cause. In one embodiment, the sealing area adjoins the blade tip area.

In one embodiment, the turbine blade is a blade for a gas or steam turbine or a blade for a turbine compressor unit.

In one embodiment, the turbine blade is a blade for a steam turbine. In one embodiment, the sealing area and / or the auxetic material can be produced and / or produced by an additive manufacturing method.

Another aspect of the present invention relates to an apparatus comprising the turbine blade and a housing having projections. The protrusions define a recess arranged and configured to at least partially receive the blade tip region of the turbine blade in the operating condition. In other words, in the operating state, the blade tip region can be arranged at least partially in a region between the projections of the housing. In other words, the blade tip region can be viewed in one direction along the fluid path. tet - overlap at least partially with the projections, without, however, that touch the blade tip region and the projections. The said projections may form guide rings of the turbomachine and / or the housing thereof.

In one embodiment, the recess and / or the

Vane tip region such, in particular thermo-mechanically, tuned that a path of the working fluid is sealed in the operating state of the turbomachine with a large sealing effect.

Another aspect of the present invention relates to a turbomachine comprising the apparatus wherein the turbomachine is a gas turbine or a steam turbine.

A further aspect of the present invention relates to the use of an auxetic material for a turbine blade for sealing a gas or vapor path during operation of the turbomachine.

Embodiments, features and / or advantages relating in the present case to the turbine blade, the device and / or the turbomachine may also relate to the use, or vice versa.

Further details of the invention are described below with reference to the drawing.

Figure 1 shows a schematic sectional or side view of a device according to the invention in a resting state. Figure 2 shows a schematic sectional or side view of the device according to the invention in an operating condition. Figure 3 illustrates in simplified terms the auxetic behavior of a material.

FIG. 1 shows a device 100 for a turbomachine (not explicitly marked) in a rest state. The device 100 may be part of the turbomachine. The apparatus 100 includes a turbine blade 10. The turbine blade 10 is shown only partially; In particular, a blade root is not shown in the figures. The turbine blade 10 is preferably a blade of a gas or steam turbine.

The dashed line B indicates the position of a rotation axis, preferably a shaft or for the turbomachine.

The turbine blade 10 comprises an airfoil 1 with a longitudinal axis A. The airfoil 1 further comprises a sealing region 2.

The sealing region 2 comprises an auxetic material for sealing a path of a working fluid during operation or in an operating state of the turbomachine. Auxetic materials are characterized by a negative Poisson number or cross-contraction number (see FIG. 3). That is, auxetic materials expand, for example, when stretched in spatial directions that are transverse or perpendicular to the stretch direction. In the present case, the direction of stretching corresponds, for example, to the longitudinal axis A (see below), so that the described expansion direction of the auxetic material (referred to as first direction, compare reference numeral 4) is perpendicular to the longitudinal axis A and parallel to the axis B of rotation.

The longitudinal axis A may define a second direction 5. The blade airfoil 1 further comprises a blade tip region 3. The blade tip region 3 is expediently arranged at an axially outer end of the blade airfoil 1. In other words, the blade tip region 3 includes a tip of the turbine blade 10.

In FIG. 1, the sealing region 2 is arranged axially inside or below the blade tip region 3. The device 100 further comprises a housing 20. The housing is preferably a stator, stator or ring segment. The housing 20 also has projections 21, which are spaced apart along the first direction 4 and perpendicular to the longitudinal axis A in such a way that the blade tip region 3 is at least partially received by a recess defined by the projections 21 (not further characterized) , or viewed along a flow direction of the working fluid, at least partially in this area, protrudes.

In the present case, the working fluid can flow along the first direction during operation of the turbomachine, that is, for example, from left to right along the axis of rotation B. Between the blade tip region 3 and the housing 20 or between the blade tip region 3 and the projections 21, a gap S is characterized, which allows a rotation of the turbine blade 10 relative to the housing 20. By the projections 21, this gap, in particular against the flow of the working fluid, such as a hot gas or

Water vapor, with which the turbine blade 10 in the operating state (see Figure 2) is applied, sealed. For efficient operation of a turbomachine, a seal of a gap between a blade tip (compare blade tip region 3) and a surrounding ring segment or housing 20 is particularly important. Unlike in FIG. 1, the sealing region 2 can be arranged in the blade tip region 3 or can be designated synonymously therewith. In FIG. 1 it is indicated that the blade tip region 3 has a distance from the projection 21 along the axis of rotation B at a distance of XI.

As a result of the design of the sealing region 2 with the auxetic material, the blade tip region 3 of the turbine blade 10 can preferably extend along the first direction 4 during the transition from the idle state to an operating state (cf. FIG. 2). In particular, the sealing region 2 is arranged and designed such that the blade tip region 3 expands during the transition from a rest state into an operating state of the turbine blade 10 and / or the turbomachine along the first direction 4, ie perpendicular to the longitudinal axis A of the blade 1. This is described in comparison and starting from Figure 1, in Figure 2 in more detail.

FIG. 2 shows the device 100 in an operating state or in a transition from the idle state to the operating state. It can be seen in particular that the turbine blade 10, in particular the blade 1, has expanded both in the axial direction (compare longitudinal axis A) and along the first direction 4, relative to the representation of FIG. 1, and thus the path of the working fluid or fluid The gap S is optimally sealed. In particular, it can be seen in FIG. 2 relative to FIG. 1 that the distance between the

Blade tip portion 3 of the projection 21 along the axis of rotation B has decreased from the distance XI to the distance X2 (<X1). The extension of the blade tip region 3 in the axial direction, that is to say along the longitudinal axis A, is preferably a creep movement due to a thermal expansion

and / or a centrifugal force, which in the operating state the turbine blade 10, in particular acts on the blade tip region 3, due. A corresponding force is indicated by the reference symbol F in FIG. The sealing preferably takes place in such a way that the working fluid almost completely reaches a pressure side of the turbine blade 10 and the turbomachine can use the fluid approximately completely, for example for energy conversion. For this purpose, the arrangement and configuration of the projections 21, but in particular the distances between the projections 21 relative to one another, are expediently adapted accordingly, for example with regard to the thermal expansion coefficient of the turbine blade 10 and the housing 20.

In particular, it can be seen in FIG. 2 that the blade tip region 3 only has a minimally large gap S both above the same relative to the housing 20 and laterally to the projections 21, so that movement of the turbine blade 10 relative to the housing 20 is possible ,

In particular, in comparison with FIG. 1, the blade tip region 3 has expanded at least along the first direction 4 due to the expansion of the sealing region 2 in this direction. The extent along said first direction, as indicated above, is due to the auxetic behavior of the auxetic material in the sealing region 2 and in particular not to a possibly also present thermal formation of the sealing region 2 along the first direction 4 (see FIG. 3). In particular, the blade tip region 3 can expand together with it due to the direct connection to the sealing region 2.

According to the embodiment shown in FIGS. 1 and 2, the blade tip region 3 preferably acts as a flywheel or pulling mass for the sealing region 2, whereby an axial expansion of the sealing region 2 along the longitudinal axis is provoked, simplified or made possible. Through the axia According to the invention, an expansion along the first direction 4 due to the auxetic behavior of the sealing area is accomplished. According to an embodiment according to the invention, in which-unlike in the figures-the blade tip region is formed by the sealing region, this region preferably extends directly through the auxetic behavior of the auxetic material along the first direction 4.

As an alternative to the illustrations and descriptions of FIGS. 1 and 2, the first direction can run into the display plane in order to describe a direction perpendicular to the longitudinal axis A of the airfoil 1. Likewise, an axis of rotation and / or a flow direction of the working fluid in operation can run into the plane of representation of the figures. According to an alternative embodiment of the present invention, the extension of the blade tip region 3 along the first direction in the transition from the quiescent state to the operating state is accomplished by means other than auxetic materials, for example parts or mechanisms known to those skilled in the art.

The embodiments of the present invention may further be carried out in combination with the prior art solutions mentioned at the beginning, ie an axial displacement of a rotor unit of the turbomachine and the use of abrasive materials, in order to solve the problem described. FIG. 3 indicates, in a qualitative simplification, the auxetic behavior of a material which according to the present invention is intended for the sealing region 2. The auxetic behavior of the corresponding material can arise at the molecular or macro level. For example, auxetic behavior can be seen in various mineral cuts. These include, for example, molybdenum (IV) sulfide, graphite, labradorite and augite. Likewise, auxetic behavior can occur with appropriately cut cristobalite thins and zinc.

In particular, in FIG. 3, the horizontal arrows show an extension of the corresponding material in a horizontal direction

Direction indicated, which due to the auxetic behavior - here indicated by the stretched fields of the material - an expansion also in the vertical direction (see dashed arrows) causes. In contrast, a normal material (without auxetic behavior) would respond to stretching in the horizontal direction with compression or shortening in a direction perpendicular to the stretch direction. The invention is not limited by the description based on the embodiments of these, but includes each new feature and any combination of features. This includes in particular any combination of features in the patent claims, even if this feature or this combination itself is not explicitly stated in the patent claims or exemplary embodiments.

Claims

claims

A turbine blade (10) for a turbomachine comprising an airfoil (1) having a blade tip region (3) and a sealing region (2), wherein the sealing region (2) comprises an auxetic material and is arranged and configured such that the blade tip region (3) during the transition from a rest state of the turbine blade (10) in an operating state of the turbine blade (10) in a first direction (4) perpendicular to a longitudinal axis (A) of the airfoil (1) expands.

A turbine blade (10) according to claim 1, wherein the sealing area (2) comprises the blade tip area (3) of the turbine blade (10).

3. turbine blade (10) according to claim 1, wherein the sealing region (2) is arranged separately from the blade tip region (3) of the turbine blade (10).

4. turbine blade (10) according to one of the preceding claims, wherein the sealing region (2) adjacent to the blade tip region (3).

A turbine blade (10) according to any one of the preceding claims, which is a blade for a gas or steam turbine or a blade for a turbine compressor unit.

An apparatus (100) for a turbomachine comprising a turbine blade (10) according to any one of the preceding claims and a housing (20) enclosing said turbine blade (10), said housing (20) further comprising projections (21) which define a recess which is arranged and adapted to at least partially receive the blade tip region (3) of the turbine blade (10) in the operating state.

7. Device (100) according to claim 6, wherein the recess and / or the blade tip area are tuned in such a way, in particular thermomechanically, that a path of a

Working fluid for the turbomachine is sealed in the operating condition with a large sealing effect.

8. turbomachine, comprising the device according to claim 6 or 7, wherein the turbomachine is a gas turbine or a steam turbine.

9. Use of an auxetic material for a turbine blade (10) for sealing a path of a working fluid in the operation of a turbomachine.