ROTOR BLADE, DISC AND ROTATIONAL BODY

Abstract

Rotor blade (15) which is designed to be inserted into a disk (17) of a rotating body (1), wherein the rotor blade (15) has a blade root (21), wherein the blade root (21) in a cross-sectional shape of the blade root (21) has at least one step of protruding parts (23) which project to opposite sides relative to a direction which includes a circumferential component, wherein the protruding parts (23) are configured to lock the blade root (21) to the disk (17), each of the protruding parts (23) has a contact surface (23a) which is configured to come into contact with the disk (17) and is inclined such that it extends from radially inside to radially outside towards a central part of the blade root (21), and each of the protruding parts (23) has a non-contact surface (23b) which is designed so that it does not come into contact with the disk (17) and is inclined so that it extends from radially inside to radially outside towards the central part of the blade foot (21), characterized by that each of the protruding parts (23) is designed to protrude from the central part of the rotor blade (15), more in a radial direction towards a radial center of the disk (17) than in a circumferential direction away from the central part of the rotor blade (15).

Description

BACKGROUND OF THE INVENTION (Field of Invention)

[0001] The present invention relates to a rotating body (e.g. a turbine rotor for a gas turbine engine or a steam turbine) which has a plurality of rotor blades and a disk in which the rotor blades are inserted. (Description of the state of the art)

[0002] A rotating body for a turbomachine, such as a gas turbine or a steam turbine, has a large number of rotor blades inserted at equal intervals within it. Each rotor blade has a root as a mounting element on its inner diametrical side, and the root is inserted into a slot in a disk located on an outer circumferential portion of the rotating body, thus connecting the rotor blade to the rotating body. The root typically has a tree-like shape with a multitude of circumferentially projecting parts, since each rotor blade must be locked in place by a fit between the root and the slot on the disk (see, for example, Patent Document 1). [related document]

[0003] [Patent document 1] JP 2017- 125 478 A JP 2008-88 832 A discloses a turbine rotor.

[0004] US 2008 / 0232972A1 discloses a rotor blade attachment for a rotor blade in a gas turbine engine.

[0005] DE 600 31 031 T2 discloses a blade root and a rotor disk of a gas turbine with a stress-reducing shape.

[0006] EP 3 293 362 A1 reveals a steam turbine. OVERVIEW OF THE INVENTION

[0007] Since the rotating body of a turbomachine, such as a gas turbine or a steam turbine, rotates at high speed, the stress caused by centrifugal force is often concentrated locally in the mounting components of the rotor blades, which have the structure described above. As a technique for improving the performance of the turbomachine, it is generally possible to further increase the rotational speed of the rotating body or to increase the height of the rotor blades. However, both techniques would lead to an increase in stress due to the increased centrifugal force. This means that the stress occurring in the rotor blade mounting components limits the improvement in the performance of the turbomachine.

[0008] To solve the above problem, one object of the present invention is to improve the shape of a blade root of a rotor blade for a rotating body and the shape of a blade groove of a disk for a rotating body in order to reduce a local stress concentration in the blade root of the rotor blade and the blade groove of the disk.

[0009] To solve the above problem, the present invention provides a rotor blade for a rotating body, wherein the rotor blade is designed to be inserted into a disk of the rotating body, wherein the rotor blade has a blade root, wherein the blade root in a cross-sectional shape of the blade root has at least one step of protruding parts that protrude to opposite sides relative to a direction that includes a circumferential component, wherein the protruding parts are designed to lock the blade root to the disk, Each of the protruding parts has a contact surface designed to come into contact with the disc and inclined to extend radially inward to radially outward toward a central part of the blade root, and Each of the protruding parts has a non-contact surface designed so that it does not come into contact with the disk and is inclined so that it extends from radially inside to radially outside towards a central part of the blade root.

[0010] The present invention further provides a disk for a rotating body, wherein the disk is designed to be inserted with a rotor blade, wherein the blade has a blade groove, wherein the blade groove in a cross-sectional shape of the blade groove has at least one stage of recessed parts which are recessed on opposite sides relative to a direction which includes a circumferential component, wherein the recessed parts are designed to lock a blade root of the rotor blades to the disk, Each of the recessed parts has a contact surface designed to come into contact with the blade root and inclined to extend radially inward to radially outward toward a central part of a blade groove, and Each of the recessed parts has a non-contact surface designed so that it is not in contact with the blade root and inclined so that it extends radially inside to radially outside towards the central part of the blade groove.

[0011] In conventional blade root and slot designs, the non-contact surfaces are inclined such that they extend radially outward to radially inward toward the central portion (i.e., they are inclined at a positive angle). In such conventional designs, a high stress concentration occurs at opposite end sections of contact portions on the contact surfaces and in arc-shaped recesses (R-shaped portions) of the blade root and slot adjacent to the contact end sections. According to the rotor blade and disk design of the present invention, the non-contact surfaces are inclined at a negative angle, i.e., in the opposite direction to that of conventional designs, so that stress concentration in the contact end sections and the R-shaped portions can be reduced without increasing the overall dimensions of the blade root and slot.

[0012] In the rotor blade according to one embodiment of the present invention, each of the projecting parts of the blade root can have a tapered cross-sectional shape. In the disk according to one embodiment of the present invention, each of the recessed parts of the blade groove can have a tapered cross-sectional shape. According to this configuration, the center of stiffness distribution in each projecting part is shifted distally, so that a load transfer path can be more reliably shifted to the central part of the contact area, thereby reducing stress concentration in the end contact sections.

[0013] In the rotor blade according to one embodiment of the present invention, the blade root can have a plurality of steps of the protruding parts. In the disk according to one embodiment of the present invention, the blade groove can have a plurality of steps of the recessed parts. According to this configuration, the rotor blade can be more reliably locked in the blade groove of the disk compared to a case in which the rotor blade has only a single step of the protruding parts.

[0014] In a rotor blade according to one embodiment of the present invention, the blade root can have an inner diametral side end section formed with an inner diametral side recess that extends radially outwards. This configuration reduces the weight of the rotor blade, resulting in a smaller centrifugal force acting on the rotor blade and consequently lower overall stress in the blade root and blade groove. Furthermore, the non-contact surfaces of the projecting portions of the inner diametral side end section are also inclined at a negative angle, shifting the center of gravity of stiffness distribution distally and reducing stress concentration in the contact end sections.

[0015] The present invention provides a rotating body comprising a plurality of rotor blades inserted into the rotating body, wherein the rotor blades are constructed according to one of the foregoing constitutions, and comprising a disk constructed according to one of the foregoing constitutions, wherein the disk has blade grooves shaped to accommodate the blade roots of the rotor blades.

[0016] In the body of revolution according to one embodiment of the present invention, in the cross-sectional shape of the body of revolution, each of the blade slots can have an inner diametral side end section which has a non-contact surface having a larger radius of curvature than a non-contact surface of the inner diametral side end section of the blade root. According to this configuration, the recessed portion of the inner diametral side section of the blade slot has a large radius of curvature, so that stress concentration at this point can be reduced.

[0017] Any combination of at least two designs disclosed in the appended claims and / or the specification and / or the accompanying drawings shall be construed as being included within the scope of the present invention. In particular, any combination of two or more of the appended claims shall likewise be construed as being included within the scope of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The present invention will be more clearly understood from the following description of preferred embodiments in conjunction with the accompanying drawings. However, the embodiments and drawings serve only for illustration and explanation and are not to be understood as limiting the scope of the present invention in any way, the scope being to be determined with reference to the accompanying claims. In the accompanying drawings, the same reference numerals are used in the various views to identify identical parts. Fig. Figure 1 shows a partially cutaway side view with a schematic representation of features of a gas turbine in which a rotating body according to a first embodiment of the present invention is used; Fig. Figure 2 shows a front view of the body of revolution according to the first embodiment of the present invention; Fig. Figure 3 shows a front view illustrating a mounting part of a rotor blade of the rotating body. Fig. 2 in an enlarged manner; Fig. 4 shows a front view with a representation of Part IV from Fig. 3 in an enlarged manner; Fig. Figure 5 shows a contour diagram illustrating calculation results relating to the effect of the embodiment. Fig. 3 refer to; Fig. Figure 6 shows a contour diagram illustrating calculation results relating to the effect of the embodiment. Fig. 3 refer to; Fig. Figure 7 shows a front view illustrating a fastening part of a rotor blade of a rotating body according to a second embodiment of the present invention in an enlarged manner; Fig. Figure 8 shows a front view of a body of revolution according to a variant of the embodiment from Fig. 7; and Fig. Figure 9 shows a front view illustrating the conventional shapes according to the state of the art of a rotor blade root and a disc slot. DESCRIPTION OF THE EXECUTION FORMS

[0019] An embodiment according to the present invention is described below with reference to the drawings.

[0020] Fig. Figure 1 shows an example of a turbomachine in which a rotating body 1 according to a first embodiment of the present invention is used. Fig. Figure 1 shows a gas turbine GT as an example of a turbomachine. The gas turbine GT compresses intake air IA from the outside by means of a compressor 3 to produce compressed air CA, directs the compressed air CA to a combustion chamber 5, and combusts the compressed air together with fuel F injected into the combustion chamber 5 to produce a fuel gas with a high temperature and high pressure. Using this fuel gas, the combustion gas drives a turbine 7. The rotation of the turbine 7 drives a load (not shown), e.g., a generator connected to a rotor, which is a rotating shaft 9 forming the rotating body 1.

[0021] The turbine 7 has a large number of stator blades 13 inserted in an inner circumferential part of a turbine casing 11, and a large number of rotor blades 15 provided on an outer circumferential part of the rotor, the stator blades and the rotor blades being arranged alternately side by side in an axial direction of the rotating body. In particular, as shown in Fig. As shown in Figure 2, the large number of rotor blades 15 are coupled to an outer circumferential part of a disk 17 which is provided in the rotating body 1, and are thereby inserted in a circumferential direction of the rotating body.

[0022] The rotating body 1 comprises: the rotating shaft 9; the disk 17, which is arranged on an outer circumferential surface of the rotating shaft 9 such that it projects in a disk-like manner; and the plurality of rotor blades 15, which are arranged circumferentially on the outer circumferential portion of the disk 17. Each of the rotor blades 15 has a blade root 21. The blade root 21 is an inner diametrically opposed portion of the rotor blade 15, which is mateably coupled to the disk 17. As shown in Fig. As shown in Figure 3, the blade root 21 of the rotor blade 15 has projecting portions 23 that extend in opposite directions relative to a direction that includes a circumferential component, the projecting portions being configured to lock the blade root 21 to the disk 17. The blade root 21 of each rotor blade 15 is shaped to have a substantially line-symmetric cross-section relative to a radial direction r of the rotating body 1. In this specification, 'cross-section' (or 'cross-sectional') refers to a section along a transverse direction of the rotating body 1.

[0023] The disk 17 has blade grooves 25 in its outer circumferential portion. Each blade groove 25 is shaped to receive a blade root 21 of a rotor blade 15 and is designed to receive the blade root 21 by a fitting. The blade groove 25 is shaped to receive the blade root 21 and has recessed portions 27 that are recessed on opposite sides relative to a direction that includes a circumferential component, the recessed portions being designed to lock the blade root 21 of the rotor blade 15 to the disk 17. Each blade groove 25 of the disk 17 is shaped to have a substantially line-symmetrical cross-section relative to the radial direction r of the rotating body 1.In this specification, "step" refers to a pair of protruding parts 23 that project circumferentially on opposite sides of the blade root 21, and a corresponding pair of recessed parts 27 that are recessed circumferentially at the same radial position on opposite sides of the blade slot 25. In the illustrated example, the blade root 21 of the rotor blade 15 has a plurality of steps (3 steps in this example) of protruding parts 23. The blade slot 25 of the disk 17 also has a plurality of steps (3 steps in this example) of recessed parts 27. In this specification, if the blade root 21 and the blade slot 25 have multiple steps, the steps are designated sequentially as the "nth step," starting from the radially outermost. That is to say, a radially outermost step is designated as the first step.

[0024] When the rotating body 1 rotates, a centrifugal force acts on each rotor blade 15. Thus, during the operation of a device (in this embodiment the gas turbine GT, as in Fig. (1 shown), in which the rotating body 1 is installed, each projecting part 23 of the blade root 21 has a surface that is mainly radially outwardly directed and serves as a contact surface 23a in contact with a surface of a blade groove 25 of the disk 17, and a surface that is mainly radially inwardly directed and serves as a non-contact surface 23b. Similarly, each recessed part 27 of the blade grooves 25 has a surface that is mainly radially inwardly directed and serves as a contact surface 27a in contact with a blade root 21, and a surface that is mainly radially outwardly directed and serves as a non-contact surface 27b.

[0025] The contact surface 23a of each projecting part 23 of the blade root 21 is inclined such that, viewed in cross-section, it extends radially inward to radially outward toward a central part of the blade root 21. Similarly, the contact surface 27a of each recessed part 27 of the blade groove 25 is also inclined such that, viewed in cross-section, it extends radially inward to radially outward toward a central part of the blade groove 25.In the following description, a “positive” angle refers to such an angle of inclination as is defined by a line extending obliquely to the central part of the blade root 21 or the blade groove 25 in a direction from radially outside to radially inside (in other words, an angle of inclination of a line extending obliquely away from the central part of the blade root 21 or the blade groove 25 in a direction from radially inside to radially outside), and a “negative” angle refers to an angle opposite to the positive angle.That is, a negative angle is defined as the angle of inclination of a line extending obliquely towards the central part of the blade root 21 or the blade groove 25 in a radially inward to radially outward direction (in other words, the angle of inclination of a line extending obliquely such that it approaches the central part of the blade root 21 or the blade groove 25 in a radially inward to radially outward direction). The contact surfaces 23a, 27a of the projecting parts 23 of the blade root 21 and the recessed parts 27 of the blade groove 25 are inclined at a negative angle.

[0026] In the present embodiment, at least one step of the projecting parts 23 of the blade root 21 of the rotor blade 15 has non-contact surfaces 23b inclined at a negative angle. Similarly, at least one step of the recessed parts 27 in the blade groove 25 of the disk 17 has non-contact surfaces 27b inclined at a negative angle.

[0027] More precisely, in the illustrated example, the non-contact surfaces 23b of the projecting parts 23 of all stages (in this example, the first and second stages) are inclined at a negative angle, unlike the non-contact surface of the last stage (in this example, the third stage) of the blade root 21. The non-contact surface 23b of the last stage, which is an inner diametrical side end section 21a of the blade root 21, is designed as a planar surface essentially perpendicular to the radial direction r. Similarly, the non-contact surfaces 27b of the recessed parts 27 of all other stages (in this example, the first and second stages) are inclined at a negative angle, unlike the non-contact surface of the last stage (in this example, the third stage) of the blade groove 25.The non-contact surface 27b of the last stage, which is an inner diametrical side-end section 25a of the blade groove 25, is designed as a curved surface that is recessed radially inwards overall. It should be noted that the shape of the recessed parts 27 of all stages (in this example, the first and second stages) differs from that of the last stage (in this example, the third stage) of the blade groove 25 of the disk 17 and essentially corresponds to the shape of the protruding parts 23 of the corresponding stages of the blade root 21 of the rotor blade 15. Therefore, the description of the shape of the recessed parts 27 of the blade groove 25 is omitted in the following section.

[0028] In the rotor blade 15 and the disk 17 of the present embodiment, the non-contact surfaces 23b, 27b of the projecting parts 23 of the blade root 21 and the recessed parts 27 of the blade groove 25 are shaped such that they extend obliquely at a negative angle, thus suppressing the generation of a local stress concentration at the blade root 21 and the blade groove 25. This effect is described in detail below.

[0029] Fig. Figure 9 shows the shapes of a blade root 21 of a rotor blade 15 and a blade slot 25 of a disk 17 for a rotating body 101 according to a general and conventional example of the prior art. In this conventional example, the non-contact surfaces 23b, 27b are inclined at a positive angle, unlike the blade root 21 and the blade slot 25 according to the present embodiment. In the blade root 21 and the blade slot 25 according to such a conventional example, a large stress concentration occurs in (1) opposing end sections (hereinafter simply referred to as "contact end sections") 31, 31 of contact parts on the contact surfaces and (2) arc-shaped recessed parts (hereinafter simply referred to as "R-shaped parts") 33 of the blade root 21 and the blade slot 25, which adjoin the contact end sections 31.

[0030] To reduce stress concentration in the contact end sections 31, it is first necessary to shift the path of a centrifugal load acting on the blade root 21 and the blade groove 25 from the opposite contact end sections 31, 32 to the central parts of the contact parts. Since a load tends to pass through a part with high stiffness, it is effective to shift the center of stiffness distribution in each projecting part 23 of the blade root 21 towards the distal side of the projecting part, thus shifting the path of the centrifugal load as described above. Conversely, to reduce stress concentration in each R-shaped part 33, it is effective to increase the radius of curvature of the R-shaped part 33.As in the present embodiment, the inclination of the non-contact surfaces of the blade root 21 and the blade groove 25 at a negative angle makes it possible to achieve such a shape change in order to create the above-mentioned effect in the blade root 21 and in the blade groove 25 without increasing the radial and circumferential dimensions of the blade root 21 and the blade groove 25.

[0031] More precisely, as in Fig. As shown in Figure 3, the rotor blade 15 according to the present embodiment is designed such that, in addition to the contact surfaces 23a of the projecting parts 23 of the blade root 21, the non-contact surfaces 23b are also inclined at a negative angle, so that each of the projecting parts 23 has an elongated cross-sectional shape compared to a conventional shape. This means that each projecting part 23 has a smaller and more uniform width dimension over its entire projecting part 23. The same applies to projecting parts between the recessed parts 27, 27 of the blade groove 25. Due to this shape, the centers of stiffness distribution in these projecting parts are shifted towards the distal sides compared to those in the conventional shape, thus reducing stress concentration in the contact end sections 31.

[0032] Furthermore, the elongated cross-sectional shape of each of the protruding parts 23 facilitates a larger radius of curvature in the non-contact parts adjacent to the contact end sections 31. In this example, as in Fig. As shown in Figure 4, the R-shaped part 33, which is located closer to a mounting face of the projecting part 23 relative to the contact end sections 31 of the projecting part 23, is formed in a curved shape with two sections having different radii of curvature. As used here, a section of the R-shaped part 33 adjacent to a contact end section 31 is referred to as the 'first R-shaped part 33A', and a section of the R-shaped part 33 adjacent to the first R-shaped part 33A and forming a tip end section of the projecting part 23 is referred to as the 'second R-shaped part 33B'. Similarly, in the conventional shape as shown in Figure 4, the R-shaped part 33 is formed in two sections with different radii of curvature. Fig. As shown in Figure 9, each of the R-shaped parts 33 adjoining the contact end sections 31 is formed in a curved shape with two sections having different radii of curvature. The first R-shaped part 33A of the present embodiment has a radius of curvature that is approximately three times larger than the radius of curvature of the first R-shaped part of the R-shaped parts of the conventional form.

[0033] Fig. 5 and Fig. Figure 6 shows calculation results of a simulated stress concentration state in the form according to the present embodiment (which is shown in Fig. 3. Form shown: example) and in the conventional form (which is in Fig. 9. Form shown: comparison example). Fig. Figure 5 shows the results of the calculation of the magnitude of a minimum principal stress (i.e., a maximum compressive stress in these sections) in the example and in the comparison example. Fig. Figure 6 shows the results of the calculation of the magnitude of a maximum principal stress (i.e., a maximum tensile stress in these sections) in the example and the comparison example. It should be noted that the contact sections between the blade root and the blade groove have the same lengths in both the example and the comparison example.

[0034] From the in Fig. The results shown in section 5 demonstrate that the concentration of compressive stress, which occurs in the contact end sections in the comparison example, is significantly reduced in this example. From the results shown in Fig. The results shown in 6 similarly show that the concentration of tensile stress, which occurs in the R-shaped parts in the comparison example, is greatly reduced in the example.

[0035] Even in the conventional form, as it is in Fig. As shown in Figure 9, it is possible, for example, to form the protruding parts 23 of the blade root 21 and the recessed parts 27 of the blade groove 25 in elongated shapes if the circumferential dimensions of the blade root 21 and the blade groove 25 may be increased, and to increase the radius of curvature of the R-shaped parts 33 if the radial dimensions of the blade root 21 and the blade groove 25 may be increased. However, it is difficult to achieve the shape change including these two factors while maintaining the overall circumferential and radial dimensions of the blade root 21 and the blade groove 25. In the present embodiment, as shown in Fig. As shown in Figure 3, however, such a change in shape can be achieved by inclining the non-contact surfaces 23b, 27b of the blade root 21 and the blade groove 25 at a negative angle, without increasing the overall dimensions of the blade root 21 and the blade groove 25.

[0036] In the present embodiment, each of the projecting parts 23 of the first stage and the second stage of the blade root 21 is furthermore designed in a tapered cross-sectional shape. That is to say, in each of these projecting parts 23, as in Fig. As shown in Figure 4, the non-contact surface 23b has a larger inclination angle θ2 relative to the radial direction r than an inclination angle θ1 of the contact surface 23a relative to the radial direction r. Similarly, each of the recessed parts 27 of the first and second stages of the blade groove 25 is formed in a tapered cross-sectional shape. That is, in each of these recessed parts 27, the non-contact surface 27b has a larger inclination angle θ2 relative to the radial direction r than an inclination angle θ1 of the contact surface 27a relative to the radial direction r.The inclination angle θ1 of the contact surface refers to an inclination angle relative to the radial direction r at a center point M1 between the opposite contact end sections 31, 31 of the contact surface, and the inclination angle θ2 of the non-contact surface refers to an inclination angle relative to the radial direction r at a center point M2 between opposite contact end sections of contact surfaces in a state where the non-contact surfaces are in contact with each other because no centrifugal force acts on the body of revolution 1. That is to say, in a case where the contact surfaces and the non-contact surfaces, considered in their cross-section, have an overall linear shape, an inclination angle of the line (i.e.,the angle of inclination at the center) is the “angle of inclination θ1” or “angle of inclination θ2” and in a case where the contact surfaces and the non-contact surfaces have a wavy or curved shape when viewed in cross-section, the angle of inclination at the center is the “angle of inclination θ1” or “angle of inclination θ2”.

[0037] Such a constitution makes it possible to shift the center of gravity of the stiffness distribution in the protruding parts 23 towards the distal sides, so that a load path can be more reliably shifted to the middle parts of the contact parts in order to reduce a stress concentration in the contact end sections 31.

[0038] Furthermore, in the present embodiment, as in Fig. Figure 3 shows that the non-contact surface 27b of the inner diametral side end section 25a (the recessed parts 27 of the last stage) of the blade groove 25 of the disk 17 has a larger radius of curvature than the non-contact surface 23b of the inner diametral side end section 21a (the protruding parts 23 of the last stage) of the blade root 21 of the rotor blade 15 when viewed in cross-sectional form. The non-contact surface 27b of the inner diametral side end section 25a of the blade groove 25 preferably has the largest possible radius of curvature so that the overall dimensions of the disk 17 can be maintained and sufficient performance in supporting the rotor blade 15 can be ensured.Therefore, the recessed parts 27 of the inner diametrical side end section 25a of the blade groove 25 are also shaped to have a large radius of curvature, so that a stress concentration on these sections can be reduced.

[0039] According to the rotor blade 15 and the disk 17 for the rotating body 1 of the present embodiment, as well as the rotating body 1 which contains these components as described above, the non-contact surfaces 23b, 27b are inclined at a negative angle, so that a stress concentration in the contact end sections 31 and the R-shaped parts 33 can be reduced without increasing the overall dimensions of the blade root 21 and the blade groove 25.

[0040] Fig. Figure 7 shows a body of revolution 1 according to a second embodiment of the present invention. In the present embodiment, the non-contact surface 23b of the last stage, which is the inner diametral side end section 21a, of the blade root 21 of the rotor blade 15 is formed with an inner diametral side recess portion 41 that extends radially outwards. Other features of the present embodiment are the same as those of the first embodiment, as shown in Fig. 3 shown.

[0041] Therefore, the formation of the inner diametral side recess 41 on the inner diametral side end section 21a of the blade root 21 of the rotor blade 15 allows for a reduction in the thickness of a part that does not significantly contribute to the support of the rotor blade 15, thus reducing the weight of the rotor blade 15. Accordingly, a lower centrifugal force acts on the rotor blade 15, and consequently, an overall lower stress occurs in the blade root 21 and the blade groove 25. Since the inner diametral side recess 41 is formed on the inner diametral side end section 21a, which corresponds to the projecting parts 23 of the last stage of the blade root 21, the non-contact surfaces 23b, 27b of the projecting parts 23 of the last stage are also inclined at a negative angle.Thus, the main distribution of stiffness in the protruding parts 23 of the last stage is shifted to the distal sides, reducing the stress concentration in the contact end sections 31.

[0042] The foregoing embodiments are described with reference to examples in which the blade root 21 has a plurality of steps of the projecting parts 23. This configuration makes it possible to lock the rotor blade 15 more reliably in the blade groove 25 of the disk 17. As shown in Fig.As shown in Figure 8, the blade root 21 of the rotor blade 15 can have a single step of the projecting parts 23, and the blade groove 25 of the disk 17 can have a single step of the recessed parts 27. Even in such a case, the only non-contact surface 23b of the projecting parts 23, which is the inner diametral side end section 21a of the blade root 21, is inclined at a negative angle such that the inner diametral side recess part 41 is formed on the inner diametral side end section 21a.

[0043] The rotor blade 15 and the disk 17 for the rotating body 1, as well as the rotating body 1 containing these components according to the present invention, can be used not only in a turbine of a gas turbine, as described by way of example in the preceding embodiments, but also in various turbomachinery, such as a compressor of a gas turbine and a steam turbine.

[0044] The invention is defined by the claims. Although preferred embodiments of the present invention have been described with reference to the drawings, various additions, modifications, or deletions can be made without altering the scope of the invention. Accordingly, such variants are included within the scope of the present invention.

Claims

[1] Rotor blade (15) designed to be inserted into a disk (17) of a rotating body (1), wherein the rotor blade (15) has a blade root (21), wherein the blade root (21) in a cross-sectional shape of the blade root (21) has at least one step of protruding parts (23) which project to opposite sides relative to a direction which includes a circumferential component, wherein the protruding parts (23) are configured to lock the blade root (21) to the disk (17), each of the protruding parts (23) has a contact surface (23a) which is configured to come into contact with the disk (17) and is inclined such that it extends from radially inside to radially outside towards a central part of the blade root (21), and each of the protruding parts (23) has a non-contact surface (23b) which is designed so that it does not come into contact with the disk (17) and is inclined so that it extends from radially inside to radially outside towards the central part of the blade foot (21), characterized by that each of the protruding parts (23) is designed to protrude from the central part of the rotor blade (15), more in a radial direction towards a radial center of the disk (17) than in a circumferential direction away from the central part of the rotor blade (15). [2] Rotor blade (15) according to claim 1, wherein each of the protruding parts (23) of the blade root (21) has a tapered cross-sectional shape. [3] Rotor blade (15) according to claim 1 or 2, wherein the blade root (21) has a plurality of steps of the protruding parts (23). [4] Rotor blade (15) according to claim 3, wherein the blade root (21) has an inner diametral side end section (21a) which is formed with an inner diametral side recess part (41) which is recessed radially outwards. [5] Disk (17) of a rotating body (1), wherein the disk (17) is designed to be fitted with a rotor blade (15), wherein the disk (17) has a blade groove (25), wherein the blade groove (25) in a cross-sectional shape of the blade groove (25) has at least one step of recessed parts (27) which are recessed on opposite sides relative to a direction which includes a circumferential component, wherein the recessed parts (27) are designed to lock a blade root (21) of the rotor blade (15) to the disk (17), Each of the recessed parts (27) has a contact surface (27a) which is designed to come into contact with the blade root (21) and is inclined to extend from radially inside to radially outside towards a central part of the blade groove (25), and Each of the recessed parts (27) has a non-contact surface (27b) which is designed so that it is not in contact with the blade root (21) and is inclined so that it extends from radially inside to radially outside towards the central part of the blade groove (25), characterized by that each of the recessed parts (27) is designed to be recessed from the central part of the rotor blade (15), more in a radial direction towards a radial center of the disk (17) than in a circumferential direction away from the central part of the rotor blade (15). [6] Disc (17) according to claim 5, wherein each of the recessed parts (27) of the blade groove (25) has a tapered cross-sectional shape. [7] Disc (17) according to claim 5 or 6, wherein the blade groove (25) has a plurality of steps of the recessed parts (27). [8] Body of revolution (1) which has: a plurality of rotor blades (15) according to any one of claims 1 to 4, wherein the rotor blades (15) are inserted in the rotating body (1); and a disk (17) according to one of claims 5 to 7, wherein the disk (17) has blade grooves (25) which are shaped to accommodate the blade feet (21) of the rotor blades (15). [9] Body of revolution (1) according to claim 8, wherein in the cross-sectional shape of the body of revolution (1) each of the blade grooves (25) has an inner diametral side end section (21a) which has a non-contact surface (27b) which is designed such that it does not come into contact with a corresponding blade root (21), wherein the non-contact surface (27b) has a larger radius of curvature than a non-contact surface (23b) of an inner diametral side end section (21a) of the blade root (21). [10] Rotor blade (15) according to claim 3 or 4, wherein the rotor blade (15) has an R-shaped part which is located closer to a mounting side of at least one of the projecting parts (23) with respect to contact end sections (31) of the projecting part (23) which is in contact with a blade groove (25) of the disk (17), wherein the R-shaped part is formed in a curved shape which is defined by a first R-shaped part (33A) which is adjacent to a contact end section (31) and a second R-shaped part (33B) which is adjacent to the first R-shaped part (33A) and forms a tip end section of an adjacent projecting part.

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