Patent Application
20230111341
This application claims benefit to German Patent Application No. DE 102021126427.8, filed on Oct. 12, 2021, which is hereby incorporated by reference herein.
The present disclosure relates to a rotor arrangement for a gas turbine with inclined axial contact surfaces formed on rotor segments, a gas turbine, and an aircraft gas turbine.
In rotor assemblies, the high thermal and mechanical effects occurring in the region of the axially abutting contact surfaces, especially during operation of the gas turbine, cause large axial stresses in each two adjacent rotor segments that form part of a group of components connected and axially clamped together by a tie-rod, which group of components includes a plurality of rotor segments. It has been found that high loads in the group of components connected by the tie-rod result in, in particular annularly shaped and radially very limited, in particular thin force-transmission zones in which pronounced axial force peaks are transmitted, which results in the undesirable high stresses mentioned. In such highly loaded force-transmission regions, there is an increased risk of wear, in particular a potential for fretting.
With regard to the general technical background, reference is made, by way of example, to the following documents: U.S. Pat. Nos. 8,459,943 B2, 8,794,923 B2, US 2011/0219781 A1 and US 2020/0291781 A1.
Directional words such as “axial,” “axially,” “radial,” “radially,” and “circumferential” are taken with respect to the machine axis of the gas turbine, unless explicitly or implicitly indicated otherwise by the context.
In an embodiment, the present disclosure provides a rotor assembly that may be used in a gas turbine. The rotor assembly has a plurality of rotor segments arranged in succession in an axial direction and interconnected in the axial direction by at least one tie-rod; and a rotor segment disposed forwardly in the axial direction having a first contact surface and a rotor segment disposed rearwardly in the axial direction having a second contact surface. The first contact surface and the second contact surface are at least partially in contact with each other. The first contact surface and the second contact surface are substantially annular in shape and extend in a radial direction and in a circumferential direction. The first contact surface and/or the second contact surface extend at least partially obliquely relative to the radial direction. An angle is formed between the first contact surface and the second contact surface when viewed in a sectional plane defined by the axial direction and the radial direction.
Subject matter of the present disclosure will be described in even greater detail below based on the exemplary figures. All features described and/or illustrated herein can be used alone or combined in different combinations. The features and advantages of various embodiments will become apparent by reading the following detailed description with reference to the attached drawings, which illustrate the following:
The present disclosure relates to a rotor assembly for a gas turbine, in particular an aircraft gas turbine, the rotor assembly having a plurality of rotor segments arranged in succession in the axial direction and interconnected in the axial direction by at least one tie-rod device, a rotor segment disposed forwardly in the axial direction having a first contact surface and a rotor segment disposed rearwardly in the axial direction having a second contact surface, the first contact surface and the second contact surface being at least partially in contact with each other, and the first contact surface and the second contact surface being substantially annular in shape and extending in the radial direction and in the circumferential direction.
Aspects of the present disclosure provide a rotor assembly that will overcome the above discussed disadvantages.
Accordingly, there is provided a rotor assembly for a gas turbine, in particular an aircraft gas turbine, the rotor assembly having a plurality of rotor segments arranged in succession in the axial direction and interconnected in the axial direction by at least one tie-rod device; a rotor segment disposed forwardly in the axial direction having a first contact surface and a rotor segment disposed rearwardly in the axial direction having a second contact surface, the first contact surface and the second contact surface being at least partially in contact with each other, and the first contact surface and the second contact surface being substantially annular in shape and extending in the radial direction and in the circumferential direction. It is provided that the first contact surface and/or the second contact surface extend at least partially obliquely relative to the radial direction, an angle being formed between the first contact surface and the second contact surface when viewed in a sectional plane defined by the axial direction and the radial direction.
By configuring the contact surfaces of axially adjacent rotor segments in this way, it is possible to avoid an annular-line-type contact or force-transmission region, which has been described hereinabove as being disadvantageous. Thus, the transmission of axial forces can be better distributed over the entire contact surface, thereby preventing the occurrence of undesired stress peaks.
In the rotor assembly, the first contact surface may be substantially parallel to the radial direction and the second contact surface may be inclined relative to the radial direction. However, the reverse configuration is also possible, in which case the second contact surface may be substantially parallel to the radial direction and the first contact surface may be inclined relative to the radial direction.
In the rotor assembly, the forward rotor segment may be a rotor blade ring and the rear rotor segment may be a seal carrier.
In the rotor assembly, the angle between the first contact surface and the second contact surface may be 0.5° to 3°, in particular 0.8° to 1.2°. The inclination or angle may be selected depending on the remaining geometry of abutting rotor segments or contact surfaces thereof. It is also conceivable that sections having different opening angles may be formed along the radial direction between the two contact surfaces. For example, the opening angle may increase from radially inward to radially outward.
According to another preferred aspect, the forward rotor segment and the rear rotor segment may be clamped together via a single contact surface pair formed by the first annular contact surface and the second annular contact surface. Such a design avoids overdeterminations in the system, such as would occur, for example, in the case of a wedge-shaped joint. Preferably, the first contact surface and the second contact surface may be configured as planar annular surfaces.
According to a further preferred aspect, both the first contact surface and the second contact surface may be inclined relative to the radial direction by no more than 10°, preferably by no more than 5°, particularly preferably by no more than 2°. This prevents the occurrence of excessive radial forces during the clamping of the rotor segments, which could contribute to causing the rotor drum to bend open during operation.
It should generally be noted that the terminology “first rotor segment” and “second rotor segment” is not used to describe the formation of pairs within the rotor assembly. In particular, a second rotor segment may, for example, also function as a first rotor segment if axially adjoined by another (altogether third) rotor segment.
A gas turbine, in particular an aircraft gas turbine, may have at least one rotor assembly as described above. In the gas turbine, the rotor assembly may form part of a low-pressure turbine or a medium-pressure turbine or a high-pressure turbine.
In the illustrated example of an aircraft gas turbine 10, a turbine center frame 34 is disposed between high-pressure turbine 24 and low-pressure turbine 26 and extends around shafts 28, 30. Hot exhaust gases from high-pressure turbine 24 flow through turbine center frame 34 in its radially outer region 36. The hot exhaust gas then flows into an annular space 38 of low-pressure turbine 26. Compressors 29, 32 and turbines 24, 26 are illustratively represented by rotor blade rings 27. For the sake of clarity, the usually present stator vane rings 31 are shown, by way of example, only for compressor 32.
The following description of an exemplary embodiment of the present disclosure relates in particular to axially adjacent or successive parts of turbine 22.
First rotor segment 40 has a first contact surface 40k. In this example, first contact surface 40k is an axially rearward surface portion, in particular in the form of an annular surface of forward rotor segment 40. Second rotor segment 42 has a second contact surface 42k. In this example, second contact surface 42k is an axially forward surface portion, in particular in the form of an annular surface of rear rotor segment 42.
First contact surface 40k and second contact surface 42k are disposed opposite each other in axial direction AR. Forward rotor segment 40 and rear rotor segment 42 are interconnected or clamped against each other in the axial direction by means of a tie-rod device(tie-rod) . As a result, first contact surface 40k and second contact surface 42k come into contact or are in contact with each other.
Contact surfaces 40k, 42k transmit or support in particular forces acting in axial direction AR within the group of rotor segments 40, 42.
As can be seen from these enlarged views, an interstitial space 46 is formed at least regionally or in some areas between the two contact surfaces 40k, 42k. This interstitial space has a small size of only a few millimeters or fractions of millimeters.
In the example shown here, second contact surface 42k of rear rotor segment 42 is slightly inclined relative to radial direction RR. Thus, a small or very acute angle α is formed between first contact surface 40k and second contact surface 42k. The inclination of second contact surface 42k is selected such that angle α is about 0.5° to 3°, in particular about 1° .
By arranging the two contact surfaces 40k, 42k obliquely to each other, axial forces can be better distributed and balanced in this region during operation of the gas turbine. In this way, undesirably high stresses can be avoided as compared to contact surfaces which are oriented parallel to each other. During operation of the gas turbine, interstitial space 46 formed between the two contact surfaces 40k, 42k is closed due to the thermal and mechanical effects, so that the contact surfaces 40k, 42k bear against each other during operation. However, this does not result in the formation of an annular-line-shaped force-transmission region where the acting axial forces are so high that fretting or the like can occur. By arranging or configuring contact surface 40k or contact surfaces 40k, 42k obliquely to each other, improved stress distribution is achieved, whereby the material of the two rotor segments 40, 42 is stressed more uniformly.
While subject matter of the present disclosure has been illustrated and described in detail in the drawings and foregoing description, such illustration and description are to be considered illustrative or exemplary and not restrictive. Any statement made herein characterizing the invention is also to be considered illustrative or exemplary and not restrictive as the invention is defined by the claims. It will be understood that changes and modifications may be made, by those of ordinary skill in the art, within the scope of the following claims, which may include any combination of features from different embodiments described above.
The terms used in the claims should be construed to have the broadest reasonable interpretation consistent with the foregoing description. For example, the use of the article “a” or “the” in introducing an element should not be interpreted as being exclusive of a plurality of elements. Likewise, the recitation of “or” should be interpreted as being inclusive, such that the recitation of “A or B” is not exclusive of “A and B,” unless it is clear from the context or the foregoing description that only one of A and B is intended. Further, the recitation of “at least one of A, B and C” should be interpreted as one or more of a group of elements consisting of A, B and C, and should not be interpreted as requiring at least one of each of the listed elements A, B and C, regardless of whether A, B and C are related as categories or otherwise. Moreover, the recitation of “A, B and/or C” or “at least one of A, B or C” should be interpreted as including any singular entity from the listed elements, e.g., A, any subset from the listed elements, e.g., A and B, or the entire list of elements A, B and C.
| Number | Date | Country | Kind |
|---|---|---|---|
| 102021126427.8 | Oct 2021 | DE | national |
