JPH10141002A - Moving blade connection tool for turbine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a moving blade connection tool for a turbine to reduce concentration of a stress, reduce a maximum stress, and shorten length in a radial direction. SOLUTION: A male type connection tool 12 arranged at the inner end part of a turbine moving blade 11 and a female type connection tool 14 arranged at the outer peripheral part of a disc 13 are adhered to and fitted in each other to transmit a centrifugal force exerted on the turbine moving blade. The moving blade connection tool is provided with at least two pressure surfaces 16 and 18 with a distance radially provided therebetween; and at least non-pressure surfaces 17 and 19 formed between the pressure surfaces and fitted in each other with a gap therebetween and transmitting no centrifugal force. The non- pressure surface comprises two large arcuate surfaces 17a and 19a adjoining two planes to form a pressure surface and having a relatively high curvature R of radius; two small arcuate surfaces 17b and 19b adjoining the two large arcuate surfaces and having a relatively small curvature (r) of radius; and planes 17c and 19c to intercouple the two small arcuate surfaces. This constitution reduces a maximum stress by reducing concentration of a stress and shortens length in a radial direction.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a blade fixing portion for connecting a turbine blade to a disk.

[0002]

2. Description of the Related Art As shown in FIG. 4, a gas turbine engine generally includes a high-pressure compressor 2, a combustor 3, and a high-pressure turbine 4, and the like. The fuel is burned in the combustor 3 by the air compressed by the combustor 3, and the high-pressure turbine 4 is driven by the high-temperature combustion gas generated by the combustor 3.

In addition, in the case of a twin-shaft turbofan engine, in addition to the above, a low-pressure turbine 5 driven by exhaust gas of a high-pressure turbine 4 and a fan 1 driven by the low-pressure turbine 5 are provided. FIG. 5 is a partial sectional view of the gas turbine unit. In this figure, a part of the air compressed by a compressor (not shown) flows into the combustor 3, generates high-temperature gas in the combustor 3, and drives the high-pressure turbine 4 and the low-pressure turbine 5 with the high-temperature gas. The compressor is driven by this driving force. A plurality of turbine blades 4a and 5a are arranged on the outer circumference of the turbines 4 and 5 to form a cascade.

FIG. 6 shows a conventional example of a blade fixing portion for connecting gas turbine blades 4a, 5a to disks 4b, 5b.
As shown in this figure, the means for fixing the moving blade are roughly divided into
There are a tangential entry type in which the rotor blades are implanted in the circumferential direction of the disk, and an axial entry type in which the rotor blades are implanted in the rotor axial direction. The axial entry dovetail
In general, in many cases, an angle (sk
ew angle) (direction of torsion with respect to the engine axis)
Is inserted into.

FIG. 7 shows an example of an axial entry type blade fixing portion. A tongue-shaped portion (referred to as a tongue portion) is provided on a moving blade and a disk, and acts on the moving blade via the tongue portion. The transmitted centrifugal force is transmitted to the disk. The axial entry type wing fixing portion is called a dovetail portion, a portion having two tongue portions is called a double tang dovetail, and a portion having only two or more tang portions is called a multi tang dovetail.

[0006]

The dovetail section is shown in FIG.
As shown in FIG. 1, the plane includes a plane (pressure surface) for transmitting the centrifugal force of the rotor blade to the disk and a surface (non-pressure surface) that does not contribute to the transmission of the centrifugal force. In a conventional dovetail configuration, the non-pressure surface has a single radius of curvature (r _1, r ₂ or r ₁₎ sandwiched between a plane forming a parallel spacing between the blade and the disk, and a plane forming the pressure surface. r ₃ ).

However, when the pressure surface and the non-pressure surface are joined by one R surface, there is a problem that the radius of the R surface is reduced and the stress concentration at the R portion is increased. Therefore, in the conventional dovetail section, when used under more severe conditions (rotational speed, operating temperature, etc.) than before, the fatigue strength is reduced due to the concentration of stress in the R section, and the life is shortened. There was a possibility that fatigue fracture may occur in the part.

If the radius of the R-plane is simply increased to solve this problem, the following problem occurs. First
In addition, an increase in the radial length of the dovetail portion increases the centrifugal force at the outer peripheral portion of the disk, and it is necessary to make the disk large enough to withstand it. Secondly, the minimum value of the cross section obtained by cutting the tab tail on the cylindrical surface around the turbine rotation axis becomes small, the average stress of this cross section becomes large, and the stress concentrated portion near this cross section becomes excessive.

The present invention has been made to solve the various problems described above. That is, an object of the present invention is to provide a blade fixed portion structure of a turbine rotor blade having a small stress concentration, capable of reducing the maximum stress generated in an arc surface stress concentration portion adjacent to a pressure surface, and having a short radial length. It is in.

[0010]

According to the present invention, a male connector provided at an inner end of a turbine rotor blade and a female connector provided at an outer peripheral portion of a disk are provided. The connector and the female connector are each fitted in close contact with each other, transmit centrifugal force acting on the turbine blade, and have at least two radially-spaced pressure surfaces and a structure between the pressure surfaces. And at least one non-pressure surface that fits with a gap therebetween and does not transmit the centrifugal force, wherein the non-pressure surface is
Two large arc surfaces adjacent to the two planes forming the pressure surface and having a relatively large radius of curvature R, and two small arc surfaces adjacent to the two large arc surfaces and having a relatively small radius of curvature r And a plane connecting the two small arc-shaped surfaces.

The configuration of the present invention has the following advantages from the viewpoint of generated stress. At the fitting part (dovetail part) between the turbine blade and the disk, the arc surface near the pressure surface
Due to the constriction, a large stress concentration occurs due to the tensile force caused by the centrifugal force and the shear force caused by the friction of the pressure surface. However, according to the configuration of the present invention, the arc portion near the pressure surface is formed by a large arc surface having a relatively large radius of curvature R. That is, the radius of curvature near the pressure surface in the curved surface portion of the dovetail is relatively increased. Thus, the radius of curvature of the stress concentration portion is increased, so that the stress concentration ratio can be reduced.

In addition, the non-pressure surface is composed of two large arc surfaces adjacent to two planes forming the pressure surface and having a relatively large radius of curvature R, and two adjacent large arc surfaces adjacent to the two large arc surfaces. It is composed of two small arc surfaces having a small radius of curvature r and a plane connecting the two small arc surfaces. That is, the radius of curvature of the curved portion of the dovetail far from the pressure surface is relatively reduced. This reduces the radial length of the dovetail, reduces the centrifugal force at the outer periphery of the disk, and reduces the radius of curvature that follows, thereby reducing the cylindrical surface centered on the turbine rotation axis. Increases the minimum value of the cross section cut by the dovetail, reduces the average stress of this cross section, reduces the maximum generated stress, reduces the weight of the disk, uses less expensive material for the disk, and extends the life of the disk be able to.

According to a preferred embodiment of the present invention,
There are the following advantages in processing. The plane of the non-pressure surface is inclined about 10 to 20 degrees with respect to a plane which is in contact with the cylindrical surface about the turbine rotation axis and which is perpendicular to the symmetry plane of the male connection.
With this configuration, when the dovetail portion of the rotor blade is ground from the circumferential direction, if the angle formed by the plane portion with the grinding direction is small, the surface roughness deteriorates, but the angle is set to about 10 to 20 degrees. By doing so, it is possible to achieve both reduction in the radial length of the dovetail portion and prevention of deterioration in surface roughness.

Further, by setting the radius of curvature R of the large arc surface having a relatively large radius of curvature to be at least about 1.5 times the radius of curvature r of the small arc surface having a relatively small radius of curvature, The processing accuracy in the stress generating portion can be increased, and the increase in stress due to the irregular shape of the shape can be reduced.

[0015]

Preferred embodiments of the present invention will be described below with reference to the drawings. In each of the drawings, common portions are denoted by the same reference numerals, and redundant description will be omitted. FIG. 1 is a configuration diagram of a turbine blade connection device according to the present invention, in which (A) shows an entire configuration and (B) shows details of a connection portion thereof. As shown in this figure, a turbine moving blade connector 10 of the present invention includes a male connecting device 12 provided at an inner end of a turbine moving blade 11 and a female connecting device provided at an outer peripheral portion of a disk 13. Tool 14.

The male connector 12 and the female connector 14 each include at least two radially spaced pressure surfaces 1.
6, 18 and at least one non-pressure surface 17, 19 respectively configured between the pressure surfaces 16, 18. The pressure surfaces 16 and 18 are flat surfaces and are closely fitted to each other,
Centrifugal force acting on turbine blade 11 (upward in this figure)
Is transmitted. In addition, the non-pressure surface 17,1
Numerals 9 are fitted with a gap therebetween so as not to transmit the centrifugal force acting on the turbine blade 11.

FIG. 1 shows the case of a double tongue dovetail (a dovetail having two pressure surfaces in the radial direction). However, the present invention is not limited to such a double tongue dovetail, but has two tongue portions. The above can be applied to a multi-tongue dovetail having three or more pressure surfaces as it is. Hereinafter, the case of the double tongue dovetail will be described.

As shown in FIG. 1, the non-pressure surfaces 17, 19
Are two large arc surfaces 17 adjacent to two planes 16 and 18 forming a pressure surface and having a relatively large radius of curvature R.
a, 19a, two small arc surfaces 17b, 19b adjacent to the two large arc surfaces 17a, 19a and having a relatively small radius of curvature r, and the two small arc surfaces 17b, 19b
And flat surfaces 17c and 19c connecting the two.

The configuration of the present invention has the following advantages from the viewpoint of generated stress. Turbine blade 12 and disk 1
In the fitting portion (dovetail portion) 3, the arc surface portion near the pressure surface may be constricted, and a large stress concentration occurs due to a tensile force caused by centrifugal force and a shear force caused by friction of the pressure surface. . However, according to the configuration of the present invention, the arc portion near the pressure surface is constituted by the large arc surfaces 7a and 19a having a relatively large radius of curvature R. That is, the radius of curvature near the pressure surface in the curved surface portion of the dovetail is relatively increased. Thus, the radius of curvature of the stress concentration portion is increased, so that the stress concentration ratio can be reduced.

The non-pressure surfaces 17 and 19 are
Two large arcuate surfaces 17a, 19a adjacent to the two planes forming 6, 6 and having a relatively large radius of curvature R;
Two small arc surfaces 17b, 19b adjacent to the two large arc surfaces 17a, 19a and having a relatively small radius of curvature r
And planes 17c and 19c connecting the two small arc surfaces 17b and 19b. That is, the radius of curvature of the curved portion of the dovetail far from the pressure surface is relatively reduced. As a result, the radial length of the dovetail is shortened, the outer peripheral centrifugal force of the disk is reduced, and the minimum value of the cross section obtained by cutting the dovetail on a cylindrical surface centered on the turbine rotation axis is increased. The average stress in this cross section can be reduced, and as a result, the maximum generated stress can be reduced, the disk can be made lighter, an inexpensive material can be used for the disk, and the life of the disk can be extended.

As shown in FIG. 1, the non-pressure surfaces 17,
The 19 planes 17c, 19c are inclined by about 10 to 20 degrees with respect to a plane which is in contact with the cylindrical surface about the turbine rotation axis and perpendicular to the symmetry plane of the male fitting. According to this embodiment, when the dovetail portion of the bucket 11 is ground from the circumferential direction, the surface roughness deteriorates when the angle formed by the plane portions 17c and 19c with the grinding direction is small, but the angle is about 10 to 20 degrees. By setting so as to achieve the above, it is possible to achieve both reduction of the radial length of the dovetail portion and prevention of deterioration of the surface roughness.

The radius of curvature R of the large arc surfaces 17a, 19a having a relatively large radius of curvature is changed by the radius of curvature r of the small arc surfaces 17b, 19b having a relatively small radius of curvature.
By setting it to about 1.5 times or more, the processing accuracy in the maximum stress generating portion can be increased, and an increase in stress due to irregular shape or the like can be reduced.

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A computer analysis of the rotor blade connector of the turbine of the present invention shown in FIG. 1 was performed by using the finite element method. From these results, it can be seen that, in most cases, the peak stress (maximum principal stress and V
on Mises stress) was found to be well below the allowable stress.

FIG. 2 is an example of deformation analysis of the dovetail portion of FIG. From this figure, it can be seen that the centrifugal force is transmitted by the entire deformation. FIG. 3 is an example of a stress analysis of a dovetail portion, and FIG.
(B) is a case of a conventional dovetail portion composed of an arc surface having a single radius of curvature and a straight surface. From this figure,
In the case of the present invention, the maximum stress generated in the rotor blade and the disk is reduced from about 80 kg / mm ^{2 in} the conventional case (B) to about 40 kg / mm ^{2 in the} present invention (A). It can be seen that the stress concentration can be remarkably reduced.

It should be noted that the present invention is not limited to the above-described embodiment, but can be variously modified without departing from the gist of the present invention. For example, in the above-described example, only the moving blade connector of the turbine has been described. However, the present invention can be applied to all turbo machines, and is particularly effective in a turbine rotor portion having a large blade weight and requiring a cooling blade. In addition, the present invention can be applied to a multi-tongue dovetail having a double tongue or more.

[0026]

As described above, according to the present invention, it is possible to reduce the maximum stress in the arcuate surface portion adjacent to the pressure surface of the dovetail portion, and to reduce the centrifugal force at the outer peripheral portion of the disk by shortening the radial length. As a result, the maximum stress generated in the rotor blades and the disk can be reduced, and
It is possible to reduce the weight of the disk, to use an inexpensive disk material, and to extend the life of the disk.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a rotor blade connector of a turbine according to the present invention.

FIG. 2 is an example of deformation analysis of a dovetail portion according to the present invention.

FIG. 3 is an example of stress analysis of a dovetail portion according to the present invention.

FIG. 4 is an overall configuration diagram of a gas turbine engine.

FIG. 5 is a partial sectional view of a gas turbine unit.

FIG. 6 is a configuration diagram of a blade fixing portion of a conventional turbine.

FIG. 7 is a configuration diagram showing an example of a conventional axial entry type wing fixing portion.

[Explanation of symbols]

 Reference Signs List 1 fan 2 high-pressure compressor 3 combustor 4 high-pressure turbine 5 low-pressure turbine 4a, 5a turbine rotor blade 10 turbine rotor blade connector 11 turbine rotor blade 12 male connector 13 disk 14 female connector 16, 18 pressure surface 17 , 19 Non-pressure surface 17a, 19a Large arc surface 17b, 19b Small arc surface 17c, 19c Plane

Claims (4)

[Claims] 1. A male connector provided at an inner end of a turbine rotor blade and a female connector provided at an outer peripheral portion of a disk, wherein the male connector and the female connector are respectively provided. At least two pressure surfaces that are closely fitted to each other, transmit centrifugal force acting on the turbine rotor blades, and are spaced apart in the radial direction, and are fitted between the pressure surfaces and are fitted with a gap therebetween. At least one non-pressure surface that does not transmit centrifugal force, the non-pressure surface being adjacent to two planes forming the pressure surface, and having two relatively large arc surfaces having a relatively large radius of curvature R;
A turbine operation, comprising: two small arc surfaces adjacent to the two large arc surfaces and having a relatively small radius of curvature r; and a plane connecting the two small arc surfaces. Wing fittings. 2. A rotor blade connector for a turbine according to claim 1, wherein said male connector and said female connector are both symmetrical. 3. The plane of the non-pressure surface is approximately 10 to 20 degrees inclined with respect to a plane which is in contact with a cylindrical surface about the turbine rotation axis and perpendicular to a symmetry plane of the male fitting. The turbine blade connection device according to claim 1, wherein: 4. The turbine blade connection according to claim 1, wherein the radius of curvature R of the large arc surface is about 1.5 times or more the radius of curvature r of the small arc surface. Utensils.