Gas turbine and turbine rotor connecting structure and fastening nut thereof

Abstract

The invention discloses a gas turbine, a turbine rotor connecting structure of the gas turbine and a fastening nut, and relates to the technical field of gas turbines. The fastening nut is applied to the turbine rotor, the turbine rotor comprises a center shaft and a stay bolt, an assembly gap is formed between the center shaft and the stay bolt, an arc-shaped groove is formed in the first end of the fastening nut, and the width of the arc-shaped groove is larger than or equal to that of the assembly gap. The arc-shaped groove is formed in the fastening nut, so that the end face of the fastening nut can completely make contact with the end face of the center hole, and stress concentration cannot be formed on the end face of the fastening nut. When the fastening nut is used, the stress borne by the fastening nut can be evenly dispersed to the arc-shaped groove. Compared with a certain point on the end face of the fastening nut for bearing all stresses, the whole arc-shaped groove bears all stresses, so that the phenomenon of stress concentration can be effectively avoided.

Description

Technical Field

[0001] The present application relates to the technical field of gas turbines, and in particular to a gas turbine and a turbine rotor connection structure and a fastening nut thereof. Background Art

[0002] Since gas turbines are developing towards high compression ratios and high turbine pre-turbine temperatures, the working environment of existing gas turbine turbine rotors is extremely harsh. They must not only withstand high temperature loads and centrifugal loads, but also withstand the hot and cold cycles of heating and cooling during start-up and shutdown. In other words, the life of the gas turbine turbine rotor is one of the important factors restricting the reliability of the gas turbine and the life of the engine. The damage tolerance fatigue life calculation method of the gas turbine turbine rotor is based on fatigue sources such as tiny cracks or defects in each component of the turbine rotor, as well as factors such as thermal loads and stress conditions. If the structural design of the turbine rotor leads to stress concentration, then the turbine rotor will generate fatigue sources such as tiny cracks during operation and gradually expand with start-up and shutdown, which will eventually cause the cracks in the turbine rotor to exceed the usable limit and fail. Therefore, in the structural design of the turbine rotor, avoiding stress concentration caused by unreasonable design is crucial for the high reliability and long life of the gas turbine.

[0003] In the turbine rotor connection structure of a certain type of gas turbine, such as Figure 1 As shown in the figure, the center shaft and the compressor shaft (not shown in the figure) are fastened together by tie bolts and fastening nuts. The tie bolts are set in the center holes of the turbine shaft and the compressor shaft, and the tight connection of the two shafts is ensured by controlling the elongation or tightening torque of the tie bolts. In order to ensure that the tie bolts can pass through the center hole smoothly, a certain assembly margin is formed between the tie bolts and the center hole during design, that is, Figure 1 As shown in the figure, after the tie rod bolt is assembled, an assembly gap will be formed with the central axis. The force on the tightening nut and tie rod bolt is mainly axial force, such as Figure 1 As shown in the figure, since the end face of the fastening nut is partially in contact with the end face of the center hole of the center shaft, Figure 1 As shown, the end face of the fastening nut is located at the critical point where it contacts the end face of the center hole, which will form stress concentration. In other words, the end face of the fastening nut is located at the critical point where it contacts the end face of the center hole, which has the risk of generating a small fatigue source. Summary of the invention

[0004] The purpose of the present application is to provide a gas turbine and its turbine rotor connection structure and fastening nut to solve the technical problem that stress concentration is easily generated in the fastening nut of the turbine rotor connection structure of the existing gas turbine.

[0005] To achieve the above objectives, this application provides the following technical solutions:

[0006] In the first aspect, the present application proposes a technical solution for a fastening nut, which is applied to a turbine rotor, wherein the turbine rotor includes a central axis and a tie rod bolt, an assembly gap is arranged between the central axis and the tie rod bolt, and an arc groove is arranged at the first end of the fastening nut, and the width of the arc groove is greater than or equal to the width of the assembly gap.

[0007] As a specific technical solution in the present application, the width of the arc groove is less than or equal to 1 / 2 times the wall thickness of the fastening nut.

[0008] As a specific technical solution in the present application, a plurality of first clamping protrusions are provided at the second end of the fastening nut, and the first clamping protrusions are distributed around the circumference of the fastening nut, and first clamping grooves are formed between adjacent first clamping protrusions.

[0009] As a specific technical solution in the present application, a first inclined surface is provided at one end of the first clamping protrusion away from the fastening nut, and the distance between the first inclined surface and the second end of the fastening nut decreases along the circumference of the fastening nut.

[0010] In a second aspect, the present application proposes a technical solution for a turbine rotor connection structure, the turbine rotor connection structure comprising:

[0011] Tie rod bolts;

[0012] A fastening nut as described in any one of the first aspects; the fastening nut can be threadedly connected to the first end of the pull rod bolt.

[0013] As a specific technical solution in the present application, a locking nut is also included; the locking nut is arranged at the first end of the tie rod bolt to limit the displacement of the fastening nut along the axial direction of the tie rod bolt.

[0014] As a specific technical solution in the present application, the locking nut can be threadedly connected to the first end of the tie rod bolt; a plastic ring is provided at one end of the locking nut; a locking groove is provided at the first end of the tie rod bolt, and the locking groove extends along the axial direction of the tie rod bolt.

[0015] As a specific technical solution in the present application, the turbine rotor connection structure includes a fastening nut as described in the first aspect; a threaded column is provided at the first end of the pull rod bolt, and the thread on the threaded column is opposite to the thread of the pull rod bolt; the locking nut can be threadedly connected to the threaded column; a plurality of second clamping protrusions are provided at one end of the locking nut close to the fastening nut, and a second clamping groove is provided between adjacent second clamping protrusions; the first clamping groove is adapted to the second clamping protrusion; the second clamping groove is adapted to the first clamping protrusion; a second inclined surface is provided at one end of the second clamping protrusion away from the locking nut, and the second inclined surface is parallel to the first inclined surface; the first clamping protrusion and / or the second clamping protrusion can form elastic deformation.

[0016] As a specific technical solution in the present application, the fastening nut and the first clamping protrusion are an integrally formed structure; the locking nut and the second clamping protrusion are an integrally formed structure.

[0017] In a third aspect, the present application proposes a gas turbine, which includes a fastening nut as described in any one of the first aspects, or includes a turbine rotor connection structure as described in any one of the second aspects.

[0018] Compared with the prior art, the beneficial effects of this application are:

[0019] The present application provides an arc groove on the fastening nut so that the end face of the fastening nut can be in full contact with the end face of the center hole, that is, the end face of the fastening nut will not form stress concentration. When the fastening nut is in use, the stress it bears will be evenly dispersed to the arc groove. Compared with a certain point on the end face of the fastening nut bearing all the stress, the entire arc groove bearing all the stress can effectively avoid the occurrence of stress concentration. If the fastening nut does not generate stress concentration, the risk of the fastening nut generating a small fatigue source can also be reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a cross-sectional schematic diagram of a turbine rotor connection structure in the prior art;

[0021] Figure 2 A three-dimensional schematic diagram of a fastening nut proposed in an embodiment of the present application;

[0022] Figure 3 A cross-sectional schematic diagram of a fastening nut proposed in an embodiment of the present application;

[0023] Figure 4 A cross-sectional schematic diagram of a turbine rotor connection structure proposed in an embodiment of the present application;

[0024] Figure 5 for Figure 4A magnified view of part A;

[0025] Figure 6 A cross-sectional schematic diagram of another turbine rotor connection structure proposed in an embodiment of the present application;

[0026] Figure 7 A schematic diagram of a locking nut and a tie rod bolt connected according to an embodiment of the present application;

[0027] Figure 8 A three-dimensional schematic diagram of a turbine rotor connection structure proposed in an embodiment of the present application;

[0028] Fig. 9 This is a schematic cross-sectional view of another turbine rotor connection structure proposed in an embodiment of the present application.

[0029] In the figure: 1, central axis; 2, tie rod bolt; 21, locking groove; 22, threaded column; 3, fastening nut; 31, stress point; 32, arc groove; 33, first clamping protrusion; 34, first clamping groove; 35, first inclined surface; 4, assembly gap; 5, locking nut; 51, plastic ring; 52, second clamping protrusion; 53, second clamping groove; 54, second inclined surface. DETAILED DESCRIPTION

[0030] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0031] It should be noted that, in the description of the present application, the terms "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating directions or positional relationships, are based on the directions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description. They do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore should not be understood as a limitation on the present application.

[0032] Furthermore, it should be understood that for the sake of ease of description, the sizes of the various components shown in the drawings are not drawn according to actual proportions. For example, the thickness or width of certain layers may be exaggerated relative to other layers.

[0033] It should be noted that like reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined or described in one drawing, it will not require further detailed discussion and description in the description of the subsequent drawings.

[0034] Before understanding the embodiments of the present application, it should be noted that in order to simplify the drawings in the present application so that technicians in this field can clearly understand the specific structures of various parts proposed in the embodiments of the present application, the threads of all parts (for example: the pull rod bolt 2, fastening nut 3, locking nut 5 and threaded column 22 mentioned below) are omitted in the drawings of the present application.

[0035] In order to solve the technical problem that the end face of the fastening nut and the end face of the center hole in the prior art partially contact each other, which will cause stress concentration, the present application proposes a fastening nut 3, which is applied to a turbine rotor. The turbine rotor includes a center shaft 1 and a tie rod bolt 2, and an assembly gap 4 is provided between the center shaft 1 and the tie rod bolt 2. The first end of the fastening nut 3 is provided with an arc groove 32, and the width of the arc groove 32 (that is, as shown in FIG. Figure 3 The width S2 shown in FIG. 1 is greater than or equal to the width of the assembly gap 4 (i.e., Figure 4 Width S3 shown).

[0036] It should be clear that if Figure 3 As shown, since the width of the arc groove 32 is greater than the width of the assembly gap 4, the end face of the fastening nut 3 (that is, the end face of the first end of the fastening nut 3) can be in full contact with the end face of the center hole, that is, the end face of the fastening nut 3 will not form a single stress point 31. Figure 5 As shown in FIG. 1 , due to the arrangement of the arc groove 32, a plurality of stress points 31 are formed on the arc groove 32. That is, in the embodiment of the present application, the stress borne by the fastening nut 3 is evenly dispersed to the arc groove 32 when in use (i.e., Figure 5 The arc groove 32 shown in the figure is on each stress point 31). Compared with a certain point on the end face of the fastening nut 3 bearing all the stress, the entire arc groove 32 bearing all the stress can effectively avoid the occurrence of stress concentration. If the stress concentration phenomenon of the fastening nut 3 is avoided, the risk of generating a small fatigue source in the fastening nut 3 can also be reduced.

[0037] In order to avoid stress concentration on the end surface of the central hole, in one embodiment of the present application, the width of the arc groove 32 may be equal to the width of the assembly gap 4 .

[0038] It should be clear that the durability of the fastening nut 3 is directly proportional to its wall thickness. That is to say, the thicker the wall thickness of the fastening nut 3, the better the durability of the fastening nut 3; the thinner the wall thickness of the fastening nut 3, the worse the durability of the fastening nut 3. It should be noted that if the width of the arc groove 32 is wider, the corresponding wall thickness of the fastening nut 3 is thinner; if the width of the arc groove 32 is narrower, stress concentration may still occur at the arc groove 32. After a lot of experimental research by the inventor, in order to ensure that the fastening nut 3 has a certain durability and that stress concentration does not occur at the arc groove 32, in one embodiment of the present application, the width of the arc groove 32 may be greater than or equal to 1 / 3 times the wall thickness of the fastening nut 3 (that is, as Figure 3 The thickness S1) shown is less than or equal to 1 / 2 times the wall thickness of the fastening nut 3.

[0039] In the embodiment of the present application, there is no restriction on the shape and structure of the fastening nut 3. For example, the fastening nut 3 can be a nut with a cylindrical shape or a nut with a hexagonal shape (the same is true for the locking nut 5 below, which will not be described in detail later). Figure 1 and Figure 4 As shown, in the application scenario of the turbine rotor connection structure proposed in the present application, the assembly space of the fastening nut 3 is limited. In order to facilitate the rotation of the fastening nut 3, in one embodiment of the present application, as shown in FIG. Figure 2 and Figure 3 As shown, the second end of the fastening nut 3 is provided with a plurality of first clamping protrusions 33, each of which is distributed around the circumference of the fastening nut 3, and a first clamping groove 34 is formed between adjacent first clamping protrusions 33. When in use, each first clamping groove 34 can be clamped with a tool, and then the fastening nut 3 can be driven to rotate by the tool.

[0040] It should be clear that the fastening nut proposed in the embodiment of the present application is provided with an arc groove so that the end face of the fastening nut can be in full contact with the end face of the center hole, that is, the end face of the fastening nut will not form stress concentration. When the fastening nut is in use, the stress it bears will be evenly dispersed to the arc groove. Compared with a certain point on the end face of the fastening nut bearing all the stress, the entire arc groove bearing all the stress can effectively avoid the occurrence of stress concentration. If the fastening nut does not produce stress concentration, the risk of the fastening nut producing a small fatigue source can also be reduced.

[0041] After introducing the fastening nut proposed in the embodiment of the present application, the following introduces a turbine rotor connection structure proposed in the present application. The turbine rotor connection structure includes a tie rod bolt 2 and a fastening nut 3 proposed in any one of the above embodiments. Figure 4 or Figure 5As shown, the fastening nut 3 can be threadedly connected to the first end of the stay bolt 2.

[0042] It should be clear that the fastening nut proposed in the embodiment of the present application is provided with an arc groove so that the end face of the fastening nut can be in full contact with the end face of the center hole, that is, the end face of the fastening nut will not form stress concentration. When the fastening nut is in use, the stress it bears will be evenly dispersed to the arc groove. Compared with a certain point on the end face of the fastening nut bearing all the stress, the entire arc groove bearing all the stress can effectively avoid the occurrence of stress concentration. If the fastening nut does not produce stress concentration, the risk of the fastening nut producing a small fatigue source can also be reduced.

[0043] In order to prevent the fastening nut from loosening due to vibration during long-term use, that is, losing the fastening effect on the central shaft 1 and the compressor shaft (not shown in the figure), in one embodiment of the present application, the turbine rotor connection structure also includes a locking nut 5. The locking nut 5 is arranged at the first end of the tie rod bolt 2, and is used to limit the displacement of the fastening nut 3 along the axial direction of the tie rod bolt 2.

[0044] In the embodiment of the present application, the locking nut 5 can be any nut that can limit the fastening nut 3 from being displaced axially upward along the tie rod bolt 2. For example, the locking nut 5 can be as shown in the following two embodiments.

[0045] Embodiment 1 of locking nut

[0046] In this embodiment, if Figure 7 As shown, the locking nut 5 can be threadedly connected with the first end of the draw rod bolt 2. A plastic ring 51 is provided at one end of the locking nut 5. A locking groove 21 is provided at the first end of the draw rod bolt 2, and the locking groove 21 extends along the axial direction of the draw rod bolt 2.

[0047] When in use, first rotate the fastening nut 3 to the preset position on the tie rod bolt 2, then rotate the locking nut 5 to the preset position on the tie rod bolt 2, and then pinch the plastic ring 51 into the locking groove 21 on the tie rod bolt 2. It is easy to understand that if the plastic ring 51 is pinched into the locking groove 21, the locking nut 5 cannot rotate under the restriction of the plastic ring 51. If the locking nut 5 cannot rotate, the locking nut 5 cannot move along the axial direction of the tie rod bolt 2. If the locking nut 5 cannot move along the axial direction of the tie rod bolt 2, the locking nut 5 can limit the movement of the fastening nut 3 along the axial direction of the tie rod bolt 2.

[0048] In the embodiment of the present application, the plastic ring 51 may be any ring that can produce plastic deformation. For example, the plastic ring 51 may be a metal ring or a plastic ring.

[0049] Embodiment 2 of locking nut

[0050] In this embodiment, if Figure 8 As shown, the first end of the pull bolt 2 is provided with a threaded column 22, and the thread on the threaded column 22 is opposite to the thread of the pull bolt 2. The locking nut 5 can be threadedly connected with the threaded column 22. The end of the first clamping protrusion 33 away from the fastening nut 3 is provided with a first inclined surface 35, and the distance between the first inclined surface 35 and the second end of the fastening nut 3 decreases along the circumference of the fastening nut 3. The end of the locking nut 5 close to the fastening nut 3 is provided with a plurality of second clamping protrusions 52, and a second clamping groove 53 is provided between adjacent second clamping protrusions 52. The end of the second clamping protrusion 52 away from the locking nut 5 is provided with a second inclined surface 54, and the second inclined surface 54 is parallel to the first inclined surface 35. The first clamping groove 34 is adapted to the second clamping protrusion 52, and the second clamping groove 53 is adapted to the first clamping protrusion 33. The first clamping protrusion 33 and / or the second clamping protrusion 52 can form elastic deformation.

[0051] In this embodiment, the first engaging groove 34 and the second engaging protrusion 52 are adapted to each other, which means that the second engaging protrusion 52 can be inserted into the first engaging groove 34, and after the second engaging protrusion 52 is inserted into the first engaging groove 34, the locking nut 5 cannot rotate freely under the restriction of the first engaging groove 34 and the second engaging protrusion 52. The second engaging groove 53 and the first engaging protrusion 33 are adapted to each other, which means that the first engaging protrusion 33 can be inserted into the second engaging groove 53, and after the first engaging protrusion 33 is inserted into the second engaging groove 53, the locking nut 3 cannot rotate freely under the restriction of the second engaging groove 53 and the first engaging protrusion 33.

[0052] In this embodiment, it is assumed that the fastening nut 3 is rotated forward to tighten the central shaft 1 and the compressor shaft. When in use, the fastening nut 3 is first rotated forward to the preset position on the tie rod bolt 2, and then the locking nut 5 is reversely rotated to the threaded column 22 until the first inclined surface 35 and the second inclined surface 54 are in contact. Further, the locking nut 5 is rotated with force. Since the first clamping protrusion 33 and / or the second clamping protrusion 52 can form elastic deformation, Figure 8 As shown, the first engaging protrusion 33 can be engaged with the second engaging groove 53; the second engaging protrusion 52 can be engaged with the first engaging groove 34. As can be seen from the foregoing, if the first engaging protrusion 33 is engaged with the second engaging groove 53, and the second engaging protrusion 52 is engaged with the first engaging groove 34, the fastening nut 3 cannot be reversely rotated, and the locking nut 5 cannot be forwardly rotated. If the fastening nut 3 cannot be reversely rotated, then Fig. 9 As shown, the fastening nut 3 is restricted between the locking nut 5 and the central axis 1 , that is, the fastening nut 3 cannot generate an axial displacement along the pull rod bolt 2 .

[0053] In the embodiments of the present application, the forward rotation may be a clockwise rotation or a counterclockwise rotation. It is easy to understand that in the present embodiment, the reverse rotation is a rotation in the opposite direction to the forward rotation. For example, if the forward rotation is a clockwise rotation, the reverse rotation is a counterclockwise rotation; if the forward rotation is a counterclockwise rotation, the reverse rotation is a clockwise rotation.

[0054] It should be noted that in the embodiment of the present application, if the fastening nut 3 and the locking nut 5 need to be disassembled, a sufficiently large torque is applied to the locking nut 5 to destroy the clamping structure between the fastening nut 3 and the locking nut 5. That is to say, in the embodiment of the present application, the clamping force formed between the fastening nut 3 and the locking nut 5 can be set according to actual needs, so that the fastening nut 3 will not be easily loosened, and the clamping structure between the fastening nut 3 and the locking nut 5 is easy to be destroyed later.

[0055] In an embodiment of the present application, the first clamping protrusion 33 can be welded or bonded to the fastening nut 3. In order to ensure the connection strength between the fastening nut 3 and the first clamping protrusion 33, in an embodiment of the present application, the fastening nut 3 and the first clamping protrusion 33 can be an integrally formed structure. For similar reasons, the locking nut 5 and the second clamping protrusion 52 can also be an integrally formed structure.

[0056] After introducing the turbine rotor connection structure proposed in the embodiments of the present application, a gas turbine proposed in the present application is introduced below. The gas turbine includes a fastening nut as proposed in any one of the above embodiments, or includes a turbine rotor connection structure as proposed in any one of the above embodiments.

[0057] It should be clear that the gas turbine proposed in the embodiment of the present application has an arc-shaped groove inside which the fastening nut is able to fully contact the end face of the fastening nut with the end face of the center hole, that is, the end face of the fastening nut will not form stress concentration. When the fastening nut is in use, the stress it bears will be evenly dispersed to the arc-shaped groove. Compared with a certain point on the end face of the fastening nut bearing all the stress, the entire arc-shaped groove bearing all the stress can effectively avoid the occurrence of stress concentration. If the fastening nut does not produce stress concentration, the risk of the fastening nut generating a small fatigue source can also be reduced.

[0058] Although the embodiments of the present application have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present application, and that the scope of the present application is defined by the appended claims and their equivalents.

Claims

1. A fastening nut (3) applied to a turbine rotor, the turbine rotor comprising a central shaft (1) and a tie rod bolt (2), an assembly gap (4) being provided between the central shaft (1) and the tie rod bolt (2), characterized in that: The first end of the fastening nut (3) is provided with an arc-shaped groove (32), and the width of the arc-shaped groove (32) is greater than or equal to the width of the assembly gap (4).

2. The fastening nut (3) according to claim 1, characterized in that: The width of the arc-shaped groove (32) is less than or equal to 1 / 2 times the wall thickness of the fastening nut (3).

3. The fastening nut (3) according to claim 1 or 2, characterized in that: The second end of the fastening nut (3) is provided with a plurality of first clamping protrusions (33), each of which is distributed around the circumference of the fastening nut (3), and a first clamping groove (34) is formed between adjacent first clamping protrusions (33).

4. The fastening nut (3) according to claim 3, characterized in that: A first inclined surface (35) is provided at one end of the first clamping protrusion (33) away from the fastening nut (3), and the distance between the first inclined surface (35) and the second end of the fastening nut (3) decreases along the circumference of the fastening nut (3).

5. A turbine rotor connection structure, characterized in that: include: Tie rod bolt (2); The fastening nut (3) according to any one of claims 1 to 4; the fastening nut (3) can be threadedly connected to the first end of the tie rod bolt (2).

6. The turbine rotor connection structure according to claim 5, characterized in that: It also includes a locking nut (5); the locking nut (5) is arranged at the first end of the pull rod bolt (2) and is used to limit the displacement of the fastening nut (3) along the axial direction of the pull rod bolt (2).

7. The turbine rotor connection structure according to claim 6, characterized in that: The locking nut (5) can be threadedly connected to the first end of the tie rod bolt (2); one end of the locking nut (5) is provided with a plastic ring (51); the first end of the tie rod bolt (2) is provided with a locking groove (21), and the locking groove (21) extends along the axial direction of the tie rod bolt (2).

8. The turbine rotor connection structure according to claim 6, characterized in that: The turbine rotor connection structure includes the fastening nut (3) as claimed in claim 4; the first end of the pull rod bolt (2) is provided with a threaded column (22), and the thread on the threaded column (22) is opposite to the thread of the pull rod bolt (2); the locking nut (5) can be threadedly connected with the threaded column (22); the locking nut (5) is provided with a plurality of second clamping protrusions (52) at one end close to the fastening nut (3), and a second clamping groove (53) is provided between adjacent second clamping protrusions (52); the first clamping groove (34) is adapted to the second clamping protrusion (52); the second clamping groove (53) is adapted to the first clamping protrusion (33); the second clamping protrusion (52) is provided with a second inclined surface (54) at one end away from the locking nut (5), and the second inclined surface (54) is parallel to the first inclined surface (35); the first clamping protrusion (33) and / or the second clamping protrusion (52) can form elastic deformation.

9. The turbine rotor connection structure according to claim 8, characterized in that: The fastening nut (3) and the first clamping protrusion (33) are an integrally formed structure; the locking nut (5) and the second clamping protrusion (52) are an integrally formed structure.

10. A gas turbine, characterized in that: It comprises a fastening nut (3) as claimed in any one of claims 1 to 4, or comprises a turbine rotor connection structure as claimed in any one of claims 5 to 9.

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