EP2725193B1 - Method for detuning the blades in a gas turbine engine and corresponding gas turbine engine. - Google Patents

Description

The present invention relates to a gas turbine.

With blades of gas turbines, so-called blade flutter can occur during operation due to aeroelastic effects.

The US 2,916,258 proposes for this purpose a detuned blade arrangement with blades, which all have different masses and thus natural frequencies. To vary the masses, the blades may be formed as solid blades with different profile thicknesses or as hollow blades, each having a central cavity, wherein the cavities of different blades are different in size.

The US 6,042,338 A proposes a vane arrangement with first and second vanes, the first vanes each having a first recess and the second vanes each having a second recess different therefrom.

The US 2002/0064458 A1 proposes a vane assembly having first and second vanes, the first and second vanes having different thicknesses. Have chord lengths, bending angles or profile shapes to vary their vibration modes.

The US 4,097,192 proposes a vane arrangement with first and second vanes, wherein the first vanes each have a recess on the vane tip and the second vanes have vane-free tips.

The object of the present invention is to provide an improved gas turbine, in particular to reduce blade flutter in a gas turbine.

This object is achieved by a gas turbine with the features of claim 1. Advantageous developments are the subject of the dependent claims.

A gas turbine according to one aspect of the present invention includes a stage assembly having one or more stages each having circumferentially alternately disposed first and second blades.

One or more of these stages may be turbine stages for venting gas, particularly one of these stages may be a high or low pressure turbine stage. Additionally or alternatively, one or more of these stages may be compressor stages for compressing gas, in particular one of these stages may be a high or low pressure compressor stage.

The first and second blades may, in particular rotorfest, blades and / or, in particular stator or housing fixed, vanes be. A gas turbine according to the present invention may therefore in particular have a (high or low pressure) turbine stage with first and second turbine blades. Additionally or alternatively, this or another (high or low pressure) turbine stage may include first and second turbine vanes. Additionally or alternatively, a gas turbine according to the present invention may include a (high or low pressure) compressor stage having first and second compressor blades. Additionally or alternatively, this or another (high or low pressure) compressor stage may include first and second compressor vanes.

One or more of these stages have first and second blades. In one embodiment, one or more of these stages are comprised of first and second blades, respectively, and do not have third blades having a different cavity arrangement therefrom. By alternately arranged first and second blades is correspondingly understood in particular an arrangement in which each first blade on both sides immediately a second blade and each second blade on both sides immediately adjacent a first blade, optionally apart from a blade pair of first or second immediately adjacent blades at an odd number Total number of shovels of the stage. A blade arrangement with only two alternately arranged blade types in one stage has surprisingly been found to be particularly favorable, in particular in order to reduce blade flutter.

In one development, blade arrangements of different, in particular adjacent, or by at least one further stage spaced turbine and / or compressor stages, and / or Leitschaufelanordnungen this or this different, in particular adjacent or at least one further stage spaced turbine and / or compressor stages, each alternately arranged first and second blades, in particular to further reduce blade flutter.

The first (guide and / or barrel) blades each have a first cavity arrangement and the second (guide and / or barrel) blades each have a second cavity arrangement different therefrom.

By means of different cavity arrangements in adjacent, alternately arranged blades, in particular their stiffness and / or mass distributions, and thus in particular their intrinsic or vibrational forms, can be varied and detuned, in particular for the same total mass of a blade. In particular, in one embodiment, the first and second blades may have different eigenmodes at, at least substantially, the same or similar natural frequency, so that pressure disturbances induced by the oscillating blades are different and propagate differently in the flow.

Additionally or alternatively, their natural frequencies can also be varied and detuned against each other. In one embodiment, in particular a first natural frequency, in particular the first bending natural frequency, of the first blades may deviate by at least 2%, in particular by at least 3% from a first natural frequency, in particular the first bending natural frequency, of the second blades. Additionally or alternatively, in one embodiment, this first natural frequency of the first blades may differ by at most 9%, in particular by at most 8%, from this first natural frequency of the second blades. A vane arrangement with such natural frequency differences in one stage has surprisingly been found to be particularly favorable, in particular to reduce blade flutter.

The first and second cavity arrangement differ according to the invention in the number of cavities. In particular, the one (first / second) cavity assembly may have one or two cavities. In one embodiment, the other (second / first) cavity arrangement can in particular comprise one or more cavities more than the one (first / second) cavity arrangement, in particular two cavities, one (first / second) cavity arrangement having a cavity, or three cavities wherein the one (first / second) cavity assembly comprises two cavities. The or the cavities may in particular, at least essentially parallel to a stacking axis of the respective blade. Two or more cavities of a cavity assembly may communicate with each other over a limited radial length, particularly at a blade tip and / or blade root near end of the cavities. A cavity in the sense of the present invention is defined in particular in at least one development cut or a section at a radial height of a blade by a closed circumferential contour and distinguished from one or more further cavities of this blade, which then according to the present invention has a plurality of cavities ,

The first and second cavity assemblies may in one embodiment, at least substantially, have the same volume. For this purpose, in one embodiment, in particular the sum of the sectional areas or the total sectional area of all cavities of the first cavity arrangement in all development cuts or cuts at all radial heights of a blade of the sum of the sectional areas or the total sectional area of all cavities of the second cavity arrangement in these development sections, at least in Essentially match. However, the same volumes can also be formed by cavities with different cut surfaces or contours in at least one development cut, in that the cavities have different extensions in the longitudinal or stacking direction of the blade and / or the cut surface difference is compensated for at a different radial height.

Additionally or alternatively, the first and second blades can have, at least substantially, the same weight, which can be realized in particular by the same total volumes explained above and thus the same amount of solid material, but equally also by, at least in sections, different blade materials.

Two cavities of a cavity arrangement can have different shapes, in particular in at least one development cut or a cut a radial height of a blade non-congruent contours. Additionally or alternatively, a cavity of one (first / second) cavity assembly and a cavity of the other (second / first) cavity assembly corresponding thereto in its relative position to the blade may have a different shape, in particular in at least one development cut or at a radial height a scoop of non-congruent contours. In general, front edge-next cavities of the first cavity arrangement and trailing-edge-adjacent cavities of the first cavity arrangement and / or front-edge-adjacent cavities of the second cavity arrangement can have a different shape.

In one embodiment, the first and second blades can be connected to one another in a materially bonded manner or, in particular, can be ur- or reshaped or welded together. In particular, the first and second blades may form a so-called Blisk (Blade Integrated Disk).

The first and / or second cavity assemblies may be formed in one embodiment with the respective blades. In particular, the blades may be cast and the cavity assemblies defined by cores. In one embodiment, the first and / or second blades are produced generatively, in particular by hardening layer-wise material locally, in particular optically, thermally and / or chemically. As a result, even more complex, in particular hermetically sealed cavity arrangements can advantageously be produced or be.

Likewise, the first and / or second cavity arrangements can also be produced after a prototyping of the blades, in particular material-removing and / or destroying, preferably by machining or vaporizing.

In one embodiment, the cavity assemblies, particularly their shape, placement within the blades, and / or their volume, are to reduce blade flutter over a stage having at least two adjacent ones Blades matched with the first or second cavity assembly. This can be done in particular simulatively and / or experimentally.

Fig. 1:

einen Teil einer Stufe mit in Umfangsrichtung wechselweise angeordneten ersten und zweiten Schaufeln einer Gasturbine nach einer Ausführung der vorliegenden Erfindung.

Further advantages and features emerge from the subclaims and the exemplary embodiment. This shows, partially schematized, the only:

Fig. 1:

a portion of a step with circumferentially alternately arranged first and second blades of a gas turbine according to an embodiment of the present invention.

Fig. 1 shows a development cut or a section at a constant radial height of a stage of a gas turbine according to an embodiment of the present invention. The stage may in particular be a turbine or compressor stage.

The step points in the circumferential direction (vertically in Fig. 1 ) alternately arranged first blades 12 and second blades 10, the outer contour, at least substantially, is the same. The blades 10, 12 may in particular be rotor-fixed blades or stator or housing-fixed vanes.

The second blades 10 each have a second cavity arrangement, each with a cavity 20 which is parallel to a stacking axis of the blade 10, in particular can be aligned with this.

The first blades 12 each have a different first cavity arrangement. The first cavity arrangement consists of two cavities 21A, 21B, which in the section of the Fig. 1 are separated from each other. In one cut at a different radial height, they can communicate with each other in one embodiment. Likewise, they may also be completed, particularly if in one embodiment the blades are made generative so that the first and second cavity assemblies are formed into urethra with the blades.

The first and second cavity arrangement thus has a different number of cavities. Nevertheless, the first and second cavity arrangements, at least essentially, the same volume. In particular, they have on average the Fig. 1 the same total sectional area, that is, the sectional area of the cavity 20 corresponds, at least substantially, the sum of the sectional areas of the cavities 21A, 21B, wherein the extension of the cavities 20, 21A, 21B in the radial direction (perpendicular to the image plane of the Fig. 1 ) also corresponds to each other, at least substantially. Equally, in one embodiment, the cavities of the first and second cavity arrangement may also have different total areas in at least one development cut. This may be compensated for in other development cuts and / or by the radial extent of the cavities to form, at least substantially, equal volumes of first and second cavity assemblies.

Incidentally, since the first and second blades correspond to each other structurally, in particular in their outer contour and their material, they have, at least substantially, the same weight.

One recognizes in Fig. 1 In addition, the first edge cavity 21A of the first cavity assembly and the cavity 21B of the first cavity assembly having a trailing edge are of a different shape. Likewise, the forward edge-closest cavity 21A of the first cavity arrangement and the forward edge-closest cavity 20 of the second cavity arrangement have a different shape.

The cavity assemblies are tuned to reduce blade flutter over a step having at least two adjacent blades with the first or second cavity assembly. For this purpose, the first bending natural frequency of the first blades 12 deviates by 5% from the first bending natural frequency of the second blades 10.

LIST OF REFERENCE NUMBERS

10

second blades

12

first shovels

20

second cavities

21A, 21B

first cavities

Claims (9)

1. A gas turbine having an arrangement of stages having at least one stage with first and second blades (12, 10) that are alternately arranged in the circumferential direction, wherein the first blades (12) in each case have a first arrangement of cavities and the second blades (10) in each case have a second arrangement of cavities that differs therefrom, characterised in that the first and second arrangement of cavities have a different number of cavities (21A, 21B; 20).
2. A gas turbine according to claim 1, characterised in that the arrangement of stages is an arrangement of turbine stages for expanding gas or an arrangement of compressor stages for compressing gas.
3. A gas turbine according to one of the preceding claims, characterised in that the first and second blades (12, 10) are rotor blades or guide blades.
4. A gas turbine according to one of the preceding claims, characterised in that a first natural frequency of the first blades (12) deviates by at least 2%, in particular at least 3%, and/or at most 9%, in particular at most 8%, from a first natural frequency of the second blades (10).
5. A gas turbine according to one of the preceding claims, characterised in that the first and second arrangement of cavities have at least substantially the same volume.
6. A gas turbine according to one of the preceding claims, characterised in that the first and second blades have at least substantially the same weight.
7. A gas turbine according to one of the preceding claims, characterised in that cavities (21A), next to the leading edge, of the one, in particular the first, arrangement of cavities and cavities (21B), next to the trailing edge, of the same arrangement of cavities and/or cavities (20), next to the leading edge, of the other, in particular the second, arrangement of cavities have different shapes.
8. A gas turbine according to one of the preceding claims, characterised in that the first and second blades are connected together in a firmly bonded manner, in particular are generatively produced.
9. A gas turbine according to one of the preceding claims, characterised in that the first and/or second arrangement of cavities are formed with the blades by primary shaping or are produced after the primary shaping of the blades.

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