JP5227241B2 - Turbine rotor, turbine rotor blade coupling structure, steam turbine and power generation equipment - Google Patents

Description

  The present invention relates to a turbine rotor rotated by steam or combustion gas.

  In the turbine rotor (rotor) of an axial flow turbine, in order to convert the flow of working fluid (steam or combustion gas) into rotational force, a plurality of turbine blades are implanted on the outer periphery of a disk attached to the shaft. It is rare. Various structures have been developed and used to date for connecting blades in this type of turbine rotor.

  One of them is a so-called reverse Christmas tree type fitting structure in which a rotor blade is coupled to a disk. In this coupling structure, a plurality of concavo-convex portions (hook portion and neck portion) having shapes corresponding to each other are provided on the disc and the rotor blade, and the rotor blade is coupled to the disc by bringing the concavo-convex portions into contact with each other and fitting together. . In this type of coupling structure, the turbine rotor rotates during operation of the turbine and a centrifugal force acts on the moving blade, and a high surface pressure is applied to the contact portion between the disk and the moving blade by the centrifugal force. In a fitting structure having such a contact portion, fretting fatigue may occur at the end portion of the contact portion due to load fluctuation or slip caused by the start / stop of the turbine or vibration.

  As a countermeasure against such fretting fatigue, there has been proposed a method of forming a thin shape on the moving blade adjacent to the end of the contact portion and the concave portion of the disk (see JP 2002-106302 A). .

JP 2002-106302 A

  However, as described above, in the method of processing the dull shape in the concave portion adjacent to the end portion of the contact portion, the curvature radius of the concave portion tends to be smaller than the original shape, and the stress concentration may be increased. . In addition, since the neck width tends to be small, there is a possibility that the minimum cross-sectional area of the disk and the moving blade is reduced and the nominal stress is increased. In other words, when the concave portion is provided with a thin shape as described above, fretting fatigue at the contact portion is enhanced, but there is a concern that the fatigue strength at the concave portion may be decreased.

  An object of the present invention is to provide a turbine rotor blade coupling structure capable of improving fretting fatigue strength without reducing fatigue strength.

In order to achieve the above object, the present invention includes a shaft, a plurality of disks attached in the axial direction of the shaft and having blade grooves, and a turbine blade having a blade implantation portion fitted into the blade grooves. In the turbine rotor, the wing implantation part has an inverted Christmas tree type wing implantation part shape provided with a wing hook part and a wing neck part, and the wing groove has a rotor hook part and a rotor neck part. A blade groove shape in which the blade hook portion and the blade neck portion are fitted together, and a fitting structure in which a convex portion and a concave portion are provided in both the blade groove and the blade implantation portion, and the blade has a contact portion which concavo-convex portion in the implanting portion and the blade groove are in contact with each other when the turbine rotor rotates, in this contact portion, to a position outside a surface on the blade implanting portion in the turbine rotor radial direction The first surface is in contact with the second surface located on the inner side of the plane a was in the turbine rotor radial direction of the blade-grooves, the protrusions of the blade implanting portion corresponding to the end portion of the contact portion A blade-side thinning shape, and the blade groove has a groove-side thinning shape, and the blade-side thinning shape includes an arc portion having an arcuate surface starting from the first surface; The blade side thinning shape is formed such that a tangential plane to the arc-shaped surface at the start point of the arc-shaped surface on the first surface and the first surface form an angle. The groove-side thinning shape includes an arc portion whose contour is an arcuate surface starting from the second surface, and the groove-side thinning shape is the arcuate shape on the second surface. The tangent plane to the arc-shaped surface at the start point of the surface makes an angle with the second surface Turbine rotor, characterized that you have been formed.

  According to the present invention, since changes in local stress and contact surface pressure in the vicinity of the end of the contact portion can be reduced, fretting fatigue strength can be improved without lowering fatigue strength.

Schematic of the turbine rotor vicinity in the power generation equipment which concerns on embodiment of this invention. The enlarged view of the wing implantation part vicinity of the turbine bucket which concerns on the 1st Embodiment of this invention. The enlarged view near the contact part of a blade implantation part and a blade groove at the time of the turbine rotor rotation which concerns on the 1st Embodiment of this invention. FIG. 3 is an enlarged view of the vicinity of a thin shape in the turbine rotor according to the first embodiment of the present invention. The figure which shows the connection structure of the conventional turbine rotor blade. The distribution diagram of the contact surface pressure in a contact part when changing the contact end part angle (theta) of a thin shape. The figure which shows the optimal range of the contact edge part angle (theta) and the thin arc radius R in the turbine rotor which concerns on the 1st Embodiment of this invention. The enlarged view of the blade implantation part vicinity of the turbine bucket which concerns on the 2nd Embodiment of this invention. The enlarged view of the contact part vicinity of a blade implantation part and a blade groove at the time of turbine rotor rotation concerning the 2nd Embodiment of this invention. FIG. 10 is an enlarged view of a vicinity of a thin shape in a turbine rotor according to a third embodiment of the present invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a schematic view of the vicinity of a turbine rotor in a power generation facility according to an embodiment of the present invention.
The power generation facility shown in FIG. 1 generates electric power using a steam turbine and includes a steam turbine rotor that is rotated by steam. The turbine rotor includes a shaft 1, a plurality of disks 2 attached in the axial direction of the shaft 1, and a plurality of turbine rotor blades 3 fixed in the circumferential direction of the disk 2.

FIG. 2 is an enlarged view of the vicinity of the blade implantation portion 7 of the turbine rotor blade 3 according to the first embodiment of the present invention. In addition, the same code | symbol is attached | subjected to the same part as the previous figure, and description is abbreviate | omitted (the following figure is also the same).
The moving blade 3 shown in FIG. 2 includes a wing implantation portion 7 and a wing portion 8. The blade implantation portion 7 is formed in a so-called inverted Christmas tree shape, and a plurality of blade hook portions (convex portions) 10 and blade neck portions (concave portions) 11 are alternately provided along the radial direction of the turbine rotor. Each blade hook portion 10 protrudes from the blade implantation portion 7 generally in the circumferential direction of the turbine rotor, and a plurality of uneven portions are formed along the radial direction of the turbine rotor.

  The blade grooves 5 are grooves formed in the axial direction of the turbine rotor in order to fit the blade implantation portions 7 of the rotor blades 3, and a plurality of blade grooves 5 are arranged on the outer periphery of the disk 2 with a predetermined interval. Each blade groove 5 is provided with a plurality of rotor hook portions (convex portions) 20 and rotor neck portions (concave portions) 21 corresponding to the shape of the blade implantation portion 7. That is, the rotor hook part (convex part) 20 engages with the wing neck part 11, and the rotor neck part (concave part) 21 engages with the wing hook part 10. Thereby, the moving blade 3 is fixed to the disk 2 by fitting the blade implantation portion 7 into the blade groove 5.

  FIG. 3 is an enlarged view of the vicinity of the contact portion 30 (region III in FIG. 2) between the blade implantation portion 7 and the blade groove 5 when the turbine rotor rotates.

As shown in this figure, when the turbine rotor rotates, the blade implantation portion 7 contacts the blade groove 5 in a planar shape at the contact portion 30. More specifically, in the contact portion 30, the surface on the blade implantation portion 7 and the outer surface (first surface) in the radial direction of the turbine rotor is the surface on the blade groove 5, and the surface of the turbine rotor. It is in contact with the inner surface (second surface) in the radial direction. This is because the moving blade 3 fixed by the fitting structure as described above moves outward in the radial direction of the turbine rotor by the centrifugal force generated when the turbine rotor rotates. As shown in FIG. 3, when the turbine rotor rotates, the surface on the blade implantation portion 7 and the inner surface in the radial direction of the turbine rotor is the surface on the blade groove 5 and in the radial direction of the turbine rotor. Separated from the outer surface at.

  In portions adjacent to the end portion of the contact portion 30 in the blade implantation portion 7 and the blade groove 5, thin shapes 41 and 42 for securing a gap between the blade implantation portion 7 and the blade groove 5 are provided.

  A thin shape (blade side thin shape) 41 on the wing implantation portion 7 side is a portion adjacent to the end portion (contact end portion) 31 of the contact portion 30, and is on the wing hook portion (convex portion) 10 side in the wing implantation portion 7. It is provided in the part. The thin groove shape (groove side thin shape) 42 on the blade groove 5 side is a portion adjacent to the end portion (contact end portion) 32 of the contact portion 30, and on the rotor hook portion (convex portion) 20 side in the blade groove 5. It is provided in the part.

  FIG. 4 is an enlarged view of the vicinity of the thinning shape 41 in FIG. 3 (region IV in FIG. 3).

As shown in this figure, the blade side thinning shape 41 in the present embodiment is formed in an arc shape. The direction in which the arc portion starts in the contact end portion 31 is determined by the contact end portion angle θ that is an angle formed by the tangent plane S of the slack shape 41 in the contact end portion 31 and the contact portion 30 (first surface). Has been. That is, the contact end angle θ is an index indicating the degree of depression in the thin shape, and the degree of depression in the thin shape decreases as the contact end angle θ increases. In the example of the slim shape 41 shown in FIG. 4, the tangent plane S at the contact end portion 31 intersects the paper surface perpendicularly and extends in a substantially horizontal direction. In addition, although the groove side thinning shape 42 is not demonstrated using an enlarged view, it shall be formed in the circular arc shape which starts with the contact edge part angle (theta) like said blade side thinning shape 41 (refer FIG. 3). .

  Next, the effect of the turbine rotor configured with the above-described coupling structure will be described. Here, in order to facilitate understanding of the effects exhibited by the present embodiment, first, a turbine rotor having a conventional coupling structure will be described.

  FIG. 5 is a view showing a conventional turbine rotor blade coupling structure. FIG. 5A is an enlarged view of the vicinity of the conventional blade implantation portion, and FIG. 5B is the vicinity of the contact portion between the blade implantation portion and the blade groove when the turbine rotor rotates in the first conventional example (FIG. 5A 5) is an enlarged view of FIG. 5 (c), and FIG. 5 (c) shows the vicinity of the contact portion between the blade implantation portion and the blade groove during rotation of the turbine rotor in the second conventional example (V in FIG. 5 (a)). FIG.

  When a turbine rotor is provided as in the first conventional example shown in FIG. 5 (b), a high surface pressure is applied to the contact portion 30, and therefore, due to load fluctuation and slip caused by turbine start / stop and vibration, Fretting fatigue may occur at the end of the contact portion 30. Therefore, in the second conventional example shown in FIG. 5 (c), a blade side thin shape is formed in a portion adjacent to the contact end portion of the contact portion 30 and on the blade neck portion (concave portion) 11 side in the blade implantation portion 7. 141 is provided to reduce fretting fatigue.

  In this way, when a concave shape is provided in the concave portion adjacent to the end portion of the contact portion 30, the curvature radius of the concave portion tends to be small as compared with the case where the concave shape is not provided, and the stress concentration may be increased. In addition, since the neck width tends to be small, the minimum cross-sectional area of the shaft and blades may be reduced and the nominal stress may be increased. In other words, when the concave portion is provided with a thin shape as described above, fretting fatigue at the contact portion is enhanced, but there is a concern that the fatigue strength at the concave portion may be decreased.

  By the way, FIG. 6 is a distribution diagram of the contact surface pressure in the contact portion 30 when the contact end portion angle θ in the thin shape is changed. More specifically, this figure has (1) a thin shape in which the arc radius (the thin arc radius R) is fixed to 2 mm and the contact end angle θ is changed to 45 degrees, 67.5 degrees, and 90 degrees. FIG. 5 shows an analysis of elasticity in a finite element model for the turbine rotor and (2) the turbine rotor having the conventional shape shown in FIG. 5, and shows the contact surface pressure distribution at the contact portion 30 on the blade groove 5 side obtained by this. .

  In the contact surface pressure distribution of this figure, in the conventional shape shown in FIG. 5, the contact surface pressure increases rapidly in the vicinity of the contact end portions 31 and 32 and local stress (peak stress) is generated. On the other hand, in the model according to the present embodiment, the rigidity in the vicinity of the contact end portions 31 and 32 is reduced by providing the thinned shapes 41 and 42 adjacent to the contact end portions 31 and 32. Thereby, in the turbine rotor having the coupling structure according to the present embodiment, the contact surface pressure at the contact portion 30 on the blade groove 5 side, which is concentrated in the contact end portions 31 and 32 in the conventional shape, can be made uniform. it can. That is, according to the present embodiment in which the convex portions 10 and 20 adjacent to the contact end portions 31 and 32 are provided with the thinned shapes 41 and 42, the local stress in the vicinity of the contact end portions 31 and 32 can be reduced. Since the change in the contact surface pressure at the contact portion 30 can be reduced, the fretting fatigue strength can be improved without reducing the fatigue strength. Therefore, according to the present embodiment, a turbine rotor with high reliability against fretting fatigue can be provided.

  By the way, in the above analysis, as shown in FIG. 6, even when the thin shapes 41 and 42 having an arc radius of 2 mm are provided, the contact surface pressure becomes 0 at the contact end portions 31 and 32 when the contact end portion angle θ becomes 45 degrees. It was discovered that It is understood that this is because the rigidity of the contact end portions 31 and 32 is excessively lowered and the contact end portions 31 and 32 are deformed by the load and lifted from the contact portion 30. That is, if the contact end portions 31 and 32 are lifted as described above, the area of the contact portion 30 is reduced and the contact surface pressure is increased. Such an increase in contact surface pressure leads to an increase in local stress at the contact end portions 31 and 32, which may lead to a decrease in fretting fatigue strength. Therefore, it was found that the contact end angle θ is preferably 45 degrees or more when the thin shapes 41 and 42 having an arc radius of 2 mm are formed.

  Therefore, based on the above, the inventors conducted a finite element analysis on the turbine rotor having the coupling structure according to the present embodiment using the arc radius R and contact end angle θ of the fillet shapes 41 and 42 as parameters. did. As a result, in order for the contact surface pressure distribution in the contact portion 30 to be smaller than that of the conventional shape and the contact area not to decrease, the thin arc radius R is set to 1 to 5 mm and the contact portion angle θ is set to 50 to 90 degrees. It was found that setting was necessary. Furthermore, it has been found that the contact end angle θ and the thin arc radius R are preferably included in the region 50 shown in FIG.

  FIG. 7 is a diagram showing the optimum ranges of the contact end angle θ and the thin arc radius R in the turbine rotor according to the present embodiment. Specifically, the region 50 is a portion where the following formulas (1) to (3) are simultaneously satisfied.

  By setting the contact end angle θ and the rounded arc radius R in this way, it is possible to prevent the contact end portions 31 and 32 from being deformed and lifted, thereby improving the fretting fatigue strength without reducing the fatigue strength. be able to.

  FIG. 8 is an enlarged view of the vicinity of the blade implantation portion of the turbine rotor blade 3 according to the second embodiment of the present invention, and FIG. 9 is the vicinity of the contact portion 30 between the blade implantation portion 7 and the blade groove 5 when the turbine rotor rotates. FIG. 9 is an enlarged view of (region IX in FIG. 8).

  The turbine rotor according to the present embodiment is different from that of the first embodiment in that the turbine rotor includes slim shapes 41A and 42A formed by combining arcs and straight lines. In FIG. 9, the blade side thinning shape 41 </ b> A is formed from an arc portion 43 provided on the contact end portion 31 side and a linear portion 44 provided in a range from the end point of the arc portion 43 to the end point of the thinning shape 41 </ b> A. Has been. That is, the slimming shape 41A is formed in a linear shape after being formed in an arc shape. Similarly, the groove-side thinning shape 42 </ b> A is formed of an arc portion 43 located on the contact end portion 32 side and a linear portion 44 provided adjacent to the arc portion 43.

  In this way, even if the fillet shapes 41A and 42A are formed by combining arcs and straight lines, the fretting fatigue strength can be improved without reducing the fatigue strength, as in the first embodiment.

  In the example shown in FIG. 9, the arcuate portion 43 is positioned on the contact end portions 31 and 32 side, and the straight portions 44 are connected to the arcuate portion 43 to form the thin shapes 41 </ b> A and 42 </ b> A. And the positional relationship between the linear portions 44 may be reversed. That is, the linear portion 44 may be positioned on the contact portion end portions 31 and 32 side, and the arc portion 43 may be connected to the linear portion 44.

  In the first embodiment, the thin shapes 41 and 42 are provided at both ends 31 and 32 of all the contact portions 30, but the thin shapes 41 and 42 are provided at both ends 31 and 32 of at least one contact portion 30. If it is, the effect of this invention will be exhibited. In this way, when providing the thin shapes 41 and 42 with respect to one part of the contact part 30, a part (for example, the outermost part in the radial direction of the turbine rotor) that is expected to be severer in fatigue strength as compared with others. It is preferable to provide the thin shapes 41 and 42 in the contact portion 30) which is located and has a larger centrifugal force than the other portions. In the present embodiment, based on this viewpoint, as shown in FIG. 8, only the two contact portions 30 positioned on the outermost side in the radial direction of the turbine rotor are provided with the slim shapes 41A and 42A.

  FIG. 10 is an enlarged view of the vicinity of the slim shape in the third embodiment of the present invention.

  The slim shape shown in this figure is equivalent to that in which the chamfered portion 45 is provided on the contact end portions 31, 32 side in the slim shape 41, 42 according to the first embodiment. The chamfered portion 45 is chamfered in the blade length direction.

  When the chamfered portion 45 is provided in this manner, the stress reduction effect of the contact end portions 31 and 32 is reduced as compared with the first embodiment, but the groove width dimension control during processing of the blade groove 5 is reduced. Becomes easy. Moreover, the loss of the contact end portions 31 and 32 can be prevented.

  In the above description, the turbine rotor that couples the turbine rotor blades with a fitting structure has been described as an example using a reverse Christmas tree type coupling structure. The present invention is applicable to any turbine rotor that has a planting portion and a blade groove provided with a convex portion and a concave portion into which the convex portion and the concave portion are fitted. Specific examples of this type of turbine rotor include a so-called saddle type and T route type.

  In the above description, the turbine rotor used in the steam turbine has been described as an example, but the present invention can also be used in a turbine rotor used in a gas turbine. Furthermore, it goes without saying that the present invention can also be used in steam turbines or gas turbines configured by arranging a plurality of turbine rotors as described above, and in power generation equipment including these steam turbines or gas turbines.

DESCRIPTION OF SYMBOLS 1 Shaft 2 Disc 3 Turbine blade 5 Blade groove 7 Blade implantation part 10 Blade hook part (convex part)
11 Wing neck (recess)
20 Rotor hook part (convex part)
21 Rotor neck (recess)
30 Contact part 31 Contact end part (wing hook part side)
32 Contact end (rotor hook side)
41 Blade-side thinning shape 42 Groove-side thinning shape 43 Arc part 44 Straight line part 45 Chamfering part 50 Area where contact end part does not rise R Arc radius S Tangent plane θ Contact end part angle

Claims (8)

A turbine rotor having a shaft, a plurality of disks attached in the axial direction of the shaft and having blade grooves, and a turbine rotor blade having blade implantation portions fitted into the blade grooves,
The wing implantation part has a wing implantation part shape of an inverted Christmas tree type provided with a wing hook part and a wing neck part,
The blade groove has a rotor hook portion and a rotor neck portion, and has a blade groove shape in which the blade hook portion and the blade neck portion are fitted together,
The blade groove and the blade implantation portion have a fitting structure in which a convex portion and a concave portion are provided, and the blade implantation portion and the uneven portion in the blade groove have a contact portion that contacts each other when the turbine rotor rotates. In the contact portion, the first surface located on the blade implanting portion and located outside in the turbine rotor radial direction is the surface located on the blade groove and located inside in the turbine rotor radial direction. 2 is in contact with the surface,
A wing-side thinning shape is provided on the convex portion of the wing implantation portion corresponding to the end of the contact portion, and a groove-side thinning shape is provided on the convex portion of the wing groove ,
The wing-side thinning shape includes an arc portion whose contour is an arc-shaped surface starting from the first surface, and the wing-side thinning shape is the start of the arc-shaped surface on the first surface. The tangent plane to the arc-shaped surface at the point and the first surface are formed so as to form an angle,
The groove-side thin shape includes an arc portion whose contour is an arc-shaped surface starting from the second surface, and the groove-side thin shape is the arc-shaped surface on the second surface. the arcuate turbine rotor, wherein Rukoto the tangent plane to the surface and the second surface are formed at an angle of at the starting point. The turbine rotor according to claim 1 ,
The blade side relief shape and the groove side relief shape, turbine, characterized in that it is formed from said arcuate portion, a straight portion provided in a range up to the end point of the shape steal from the end point of the arcuate portion Rotor. The turbine rotor according to claim 1 or 2 ,
The turbine rotor according to claim 1, wherein radii of the arc-shaped surfaces in the blade side thin shape and the groove side thin shape are 1 to 5 mm, respectively. In the turbine rotor according to any one of claims 1 to 3 ,
The angle formed between the tangent plane and the first surface in the blade side corner shape and the angle formed between the tangential plane and the second surface in the groove side corner shape are set in a range of 50 to 90 degrees , respectively. turbine rotor, characterized by that. In the turbine rotor according to any one of claims 1 to 4 ,
The turbine rotor according to claim 1, wherein end portions on the contact portion side of the circular arc portion of the blade side thin shape and the groove side thin shape are chamfered. In the turbine rotor according to any one of claims 1 to 5 ,
The blade-side thinning shape and the groove-side thinning shape are provided at a contact portion located on the outermost side in the radial direction of the turbine rotor. A steam turbine comprising a plurality of turbine rotors according to any one of claims 1 to 6 . Power plant, characterized in that it comprises a turbine rotor according to any one of claims 1 to 7.

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