JPH07332003A - Turbine blades - Google Patents

Abstract

(57) [Summary] [Object] An object of the present invention is to provide a blade structure which is rigidly connected to form a single ring around the entire circumference without loosening the connection state with the adjacent blades during operation of the turbine. This is to provide a turbine rotor blade having an increased vibration damping effect and improved vibration resistance by maintaining the vibration resistance. A turbine moving blade provided on an outer peripheral portion of a disk of a turbine rotor has a shroud formed integrally with the blade of the turbine moving blade, and a dovetail groove shape is formed at both circumferential ends of the shroud. Turbine blades with convex and concave portions respectively formed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a turbine rotor blade of a gas turbine, a steam turbine, a jet engine of an aircraft or the like.

[0002]

2. Description of the Related Art Generally, a turbine rotor blade is constantly excited by a flow of working fluid and its turbulent components in a wide frequency range, so that vibration occurs at many natural frequencies of the rotor blade. However, not all vibration is a problem in the reliability problem of the blade, and it is necessary to avoid resonance during turbine operation only for the natural vibration of the blade that has the same frequency component as the exciting force that is large enough to damage the blade. There is. On the other hand, in many cases, the natural vibration having the same frequency component as the exciting force that is not enough to damage the blade cannot be taken into consideration in the design.

The vibration response of the blade structure to these various excitation forces is related to the natural frequency and the magnitude of damping in each vibration mode. Therefore, in order to design a wing structure that is reliable even if it resonates in the high-order vibration mode with a small resonance response, while avoiding the resonance of a low-order vibration mode with a large resonance response, connect adjacent wings with a shroud. Many means have been adopted. This is because if the adjoining blades are connected, an increase in the rigidity of the blade structure and an additional effect of vibration damping can be expected.

FIG. 6 shows an example of a turbine rotor blade manufactured by integrally molding a shroud and a blade. In FIG. 6, 1'is a shroud, 2 is a blade, 3 is a blade root portion, and 4 is a disk portion of a turbine rotor. This turbine rotor blade is planted in a groove provided on the outer periphery of the disk of the turbine rotor, and the shroud provided at the tip of the rotor rotor makes circumferential contact with the adjacent blades, forming a single ring on the entire circumference. To be connected.

A method of mounting the turbine rotor blade shown in FIG. 6 will be described with reference to FIG. When the shroud 1 ′ of the turbine rotor blade has a parallelogram-shaped cross section and the circumferential pitch 32 is longer than the theoretical pitch 33 of the rotor blade, the turbine rotor blade is mounted on the disk portion of the turbine rotor. , If the shroud is arranged in addition to the circumferential force 34, the force of contact with the adjoining blades is increased, and the rigidity of the blade structure is increased.

[0006]

The conventional method as described above has the following problems.

During operation of the turbine, the turbine blades are radially expanded 36 as shown in FIG. 8 due to centrifugal force and thermal expansion, so that the contact force at the shroud portion is weakened.
Therefore, when the turbine is stationary, the blade structure of the turbine rotor blades that were connected so as to form one ring in the circumferential direction,
A rattling 35 is generated between the shrouds, and the adjacent blades are not connected to each other, and each blade vibrates independently. Therefore, it exhibits a vibration characteristic remarkably different from the vibration characteristic originally planned. As a result, the turbine rotor blade may be damaged.

When the shroud of the turbine rotor blade is formed longer than the theoretical pitch of the rotor blade and the turbine rotor blade is attached to the disk portion of the turbine rotor,
It is necessary to apply a force in the circumferential direction of the shroud, but assuming backlash, a larger force must be applied,
A burden on the manufacturing process.

Further, when the turbine rotor blade is attached to the disk portion of the turbine rotor, no matter how much force is applied to the shroud when the turbine is operating, no matter how much force is applied in the circumferential direction of the shroud, assuming backlash. It is difficult to predict whether it will become smaller, and it is also difficult to actually measure its force.

An object of the present invention is to provide a vibration damping effect by maintaining a blade structure that is rigidly connected and forms one ring over the entire circumference without loosening the connection state with the adjacent blades during turbine operation. And to provide a turbine blade with improved vibration resistance.

[0011]

A turbine moving blade for achieving the above-mentioned object is provided with a circumferential direction by utilizing a force which causes expansion in the radial direction due to centrifugal force or thermal expansion and causes backlash in the circumferential direction. It was devised based on the idea that the connection state can be kept rigid by providing both ends of the shroud with uneven surfaces for applying a tensile force to the.

(1) According to the present invention, in a turbine rotor blade provided on an outer peripheral portion of a disk of a turbine rotor, a tip end of the turbine rotor blade has a shroud integrally formed with the blade, and the shroud is arranged in a circumferential direction. The main point is that a dovetail-shaped convex portion and a concave portion are formed at both ends.

(2) In the present invention according to (1), a line segment that circumferentially connects the concave surface on the side where the convex portion of the shroud of the turbine blade is formed and the concave surface on the side where the concave portion is formed. The essential point is that the shortest length of is equal to or longer than the longest circumferential length of the blade root of the turbine rotor blade.

[0014]

With the turbine rotor blade according to the present invention, since the shroud integrally formed with the blade is formed with dovetail groove-shaped projections and recesses at both ends in the circumferential direction, the adjacent blades have dovetail groove shape. The concave and convex portions are connected to each other in the circumferential direction. Therefore, centrifugal force and thermal expansion work during turbine operation,
Even if the turbine rotor blades expand outward in the radial direction, the circumferential tensile force acts on the dovetail groove-shaped irregularities provided on the shroud, so adjacent blades do not rattle between the shrouds. On the contrary, it is possible to connect the adjacent wings more robustly than when they are stationary.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of the present invention will be described below with reference to FIGS.
Will be described in detail.

FIG. 1 is an overall configuration diagram of a turbine rotor blade incorporating the present invention. Further, FIG. 2 is a schematic view of the connecting portion of the shroud as viewed from the upper side in the radial direction, FIG. 3 is a view showing the assembling process of the turbine rotor blade, and FIG. 4 is an assembly diagram in which the last one of the turbine rotor blades is embedded. FIG. 8 is a view showing the backlash of the shroud generated when the turbine is operating.

In FIG. 1 showing the first embodiment, 1 is a shroud, 2 is a blade, 3 is a blade root portion, and 4 is a disk portion of a turbine rotor. Further, in FIG. 2, 5 indicates a shroud contact surface in the shape of a dovetail groove, and 6 indicates a tensile force acting when the turbine is in operation. Further, in FIG. 3, reference numeral 7 denotes the turbine rotor blade insertion direction, 8 denotes the turbine rotor blade moving direction, and 9 denotes the turbine rotor blade insertion notch. Also, FIG.
In, 10 is the last one in incorporating turbine blades
A turbine blade of the book, 11 is a turbine blade installed in front of the turbine blade 10, and 12 is a pin. further,
In FIG. 8, 1'is a shroud, 35 is a backlash, and 36 is a radial extension.

First, referring to FIG. 8, a description will be given of a state in which a turbine is operating with a structure in which adjacent blades are connected by a shroud integrally formed with the blades. When the turbine is in operation, centrifugal force or thermal expansion causes expansion 36 in the radial outside. For this reason, the shroud portion that was in contact when stationary is separated, and backlash 35 is generated in the circumferential direction.

On the other hand, in the turbine rotor blade incorporating the present invention, the adjacent blades are shrouded as shown in FIG.
Since they are connected by the dovetail-shaped concave and convex portions provided in, there is no backlash between the shrouds.

The reason will be described in detail with reference to FIG.
As shown in FIG. 2, the turbine rotor blade incorporating the present invention has the shroud contact surface 5 that physically comes into contact with the adjacent blades due to the dovetail-shaped concave and convex portions without being separated from each other in the circumferential direction. Therefore, even if centrifugal force or thermal expansion is applied when the turbine is in operation, the tensile force 6 in the circumferential direction acts on the shroud contact surface, and the forces are balanced. In other words, instead of rattling between the shrouds of adjacent blades when the turbine is operating, the forces that attract each other act on the contrary, so the blade connection becomes more rigid than when stationary, and one ring is formed over the entire circumference. You can maintain a perfect wing structure. Therefore, the vibration damping effect of the turbine rotor blade is increased and the vibration resistance strength is improved.

Next, an example of a method for assembling a turbine rotor blade according to the present invention will be described in detail with reference to FIGS. 3 and 4.
In FIG. 3, since the turbine rotor blade insertion notch 9 is provided in the turbine rotor disk portion 4, the turbine rotor blade can be incorporated into the turbine rotor disk portion 4 in the insertion direction from the outer circumferential side in the radial direction. At this time, the turbine blade inserted first has the dovetail-shaped recesses and protrusions of the shroud formed on the turbine blades to connect with the turbine blades inserted from the outer peripheral side in the radial direction. You need to be in a place where you can fit. Further, if it is confirmed that the adjoining blades are connected to each other, in order to subsequently insert the turbine moving blades, the turbine moving blades are displaced by one pitch in the circumferential direction as the moving direction 8 shown in the drawing. Turbine rotor blades are sequentially assembled according to the above procedure.

However, if all the turbine rotor blades have the structure shown in FIG. 3, when the last one turbine rotor blade is mounted on the disk of the turbine rotor, the shroud of the turbine rotor blade already installed is projected. The part will block the insertion. Therefore, as shown in FIG. 4, for example, a dovetail groove-shaped convex portion is provided at each circumferential end of the shroud of the last turbine moving blade 10.
The shroud of the turbine rotor blade 11 incorporated in front of the above is provided with dovetail-shaped recesses at both ends in the circumferential direction. With such a structure, the last turbine blade, which is the last one, is inserted from the outer peripheral side in the radial direction and attached to the rotor disk without being blocked by the shroud, and the effect of the present invention can be realized. Here, the turbine rotor blade 11 may not be incorporated immediately before the turbine rotor blade 10 but may be incorporated first in the disk portion of the turbine rotor. Also, since the last turbine blade, which is the last one, cannot be embedded in the groove provided on the outer circumference of the disk portion of the turbine rotor like other turbine blades, it is fixed to the disk portion of the turbine rotor by the pin 12 or the like. Is desirable.

Further, if adjacent blades are connected by the circumferential tensile force acting on the shroud when the turbine is in operation, the dovetail-shaped irregularities provided on the shroud of the turbine rotor blade according to the present invention are slightly Even if there is some backlash, it is acceptable. In that case, at the time of assembly, there is an advantage that the dovetail groove-shaped uneven portions provided on the respective shrouds can be easily assembled.

Next, a second embodiment of the present invention will be described with reference to FIG.

FIG. 5 is a schematic view of a turbine rotor blade showing a second embodiment of the present invention, 21 indicates a shroud line segment, and 22 indicates a blade root line segment.

In the second embodiment of the present invention, in FIG. 5, among the lengths connecting the most concave surface of the concave portion and the most concave surface of the convex portion of the uneven portion provided at both ends in the circumferential direction of the shroud 1, When the shortest length is the shroud line segment 21 and the longest line segment in the circumferential direction of the blade root is the blade root line segment 22, the shroud line segment is longer than the length of the blade root line segment 22. The length of 21 is equal to or greater than. Therefore, even when the device shown in FIG. 4 is not devised, when assembling a turbine moving blade incorporating the present invention, the last one turbine moving blade is also not blocked by the shroud, and from the outer peripheral side in the radial direction. It is inserted and attached to the rotor disk.

Further, according to the second embodiment of the present invention, since all the blades of the turbine rotor blade attached to the disk of the turbine rotor have the same structure, the blade is different from the structure of FIG. 4 described above. The fact that the vibration characteristics are the same one by one and there is no variation is excellent in predicting the vibration damping effect, and is desirable in terms of the vibration resistant structure.

[0028]

As described above, according to the present invention, the connection state with the adjoining blades during operation of the turbine is not loosened,
Since it is possible to maintain a blade structure that is rigidly connected and forms one ring over the entire circumference, it is possible to configure a turbine rotor blade having an increased vibration damping effect and improved vibration resistance.

[Brief description of drawings]

FIG. 1 is an overall view showing a first embodiment of the present invention.

FIG. 2 is a schematic diagram of a shroud.

FIG. 3 is an assembly view of a turbine rotor blade.

FIG. 4 is an assembly view of a turbine rotor blade.

FIG. 5 is a schematic diagram showing a second embodiment of the present invention.

FIG. 6 is an overall view showing a conventional example.

FIG. 7 is an assembly diagram of a conventional example.

FIG. 8 is a schematic diagram of a turbine rotor blade when the turbine is operating.

[Explanation of symbols]

1, 1 '... Shroud, 2 ... Blade, 3 ... Blade root portion, 4 ... Turbine rotor disk portion, 5 ... Shroud contact surface, 6
... Tensile force, 7 ... Turbine blade insertion direction, 8 ... Turbine blade movement direction, 9 ... Turbine blade insertion notch, 10,1
DESCRIPTION OF SYMBOLS 1 ... Turbine rotor blade, 12 ... Pin, 21 ... Shroud line segment, 22 ... Blade root line segment, 32 ... Circumferential pitch, 33
... theoretical pitch, 34 ... circumferential force, 35 ... play, 36 ... elongation.

Claims (2)

[Claims] 1. A turbine rotor blade provided on an outer peripheral portion of a disk of a turbine rotor, wherein a tip end of the turbine rotor blade has a shroud integrally formed with the blade, and ants are provided at both circumferential ends of the shroud. A turbine rotor blade having groove-shaped convex portions and concave portions formed respectively. 2. The shortest length of a line segment that connects the concave surface on the side where the convex portion of the shroud of the turbine rotor blade is formed and the concave surface on the side where the concave portion is formed in the circumferential direction according to claim 1. Is equal to or longer than the longest circumferential length of the blade root portion of the turbine rotor blade.