JP3346277B2 - Compressor rotor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a compressor rotor which is a component of a gas turbine, and is particularly suitable for a compressor rotor formed by combining rotor disks of different materials having different coefficients of thermal expansion.

[0002]

2. Description of the Related Art The material used for the rotor disk of a compressor incorporated in a gas turbine is selected according to the environmental temperature of the rotor disk and the stress generated thereby.

FIG. 2 is a sectional view showing a general structure of a gas turbine, which comprises a compressor 1, a combustor 2 and a turbine 3. The compressor 1 adiabatically compresses the air sucked from the atmosphere into the gas path 4, the combustor 2 mixes and burns the fuel with the compressed air supplied from the compressor 1 to generate a high-temperature, high-pressure gas, and the turbine 3 Generates rotational power when the combustion gas introduced from the combustor 2 expands. Exhaust from the turbine is released to the atmosphere. The remaining power obtained by subtracting the power for driving the compressor 1 from the rotational power generated by the turbine 3 becomes the generated power of the gas turbine and drives the generator.

[0004] The rotor of the compressor is composed of rotor disks stacked in multiple stages from upstream to downstream of a working fluid (air). A front rotor disk having a rotating shaft extending forward; a last rotor disk having a rotating shaft extending rearward; and an intermediate rotor disk sandwiched between the front and last rotor disks. I have.

Since the working fluid flowing from the front to the rear through the gas path 4 rises in temperature each time it passes through the rotor disk by the adiabatic compression by the compressor 1, the outer peripheral portion of the rotor disk at the rear stage of the compressor has a high temperature environment. Exposed to
Therefore, it is necessary to use a material having high strength in a high-temperature environment as a material of the rotor disk on the downstream side of the compressor.

The high-temperature high-strength material is an expensive alloy material such as a Ni-base alloy, so that a high-temperature high-strength material is provided on the rear side of the compressor and a normal temperature or a somewhat high temperature such as low-alloy steel is provided on the front side. It is common to use a combination of materials so as to use an inexpensive room-temperature high-strength material (hereinafter, referred to as a low-strength material) that has high strength in a low temperature range and low strength at high temperatures, thereby reducing costs.

However, high-temperature high-strength materials tend to have a higher thermal expansion coefficient than low-strength materials, and when used in combination with a low-strength material having a low thermal expansion coefficient, thermal expansion near the fitting portion where the two are combined. The phenomenon of pushing up and down due to the difference (described later in the embodiment) becomes remarkable. Although the physical properties (coefficients of thermal expansion) of the materials used did not differ greatly within the range of the conventional design conditions, recently, there has been a tendency to set the discharge pressure of the compressor higher than before, The difference in the physical property values is large.

Further, even when the same material is used, there has been a tendency to adopt a structure for reducing the difference in thermal expansion by making the environmental temperature uniform. This is because the effect of pushing up and down due to the difference in thermal expansion due to the difference in the environmental temperature itself is greater.

Further, as an example of reducing the thermal expansion difference by making the environmental temperature uniform, the one described in, for example, JP-A-2-81902 is known. FIG. 3 is a structural cross-sectional view of the turbine section. The gas turbine rotor is a stacked rotor in which a plurality of rotor blades attached to the outer peripheral portion are overlapped in a multi-stage unit in the rotation axis direction via spacers. .

In the figure, the left side is the upstream front side and the right side is the downstream rear side, 8 is a rotor disk, 9 is a moving blade attached to the outer periphery of the rotor disk 8, 10 is a stationary blade, 11
Is a shroud that restrains the tip of the stationary blade 10, and 12 is a spacer that is inserted between the rotor disks 8, 8 '. A group of bleed holes 13 is provided on the circumference centered on the rotor disk axis through the spacer 12 interposed between the rotor disk 8 and the rotor disk 8 ′. Is flowed from the former stage to the latter stage. The medium guided to the group of holes 13 is discharged to the outside of the rotor disk after uniformizing the temperature of the surrounding rotor disk 8 through all stages, thereby equalizing the environmental temperature, and reducing the thermal expansion difference due to the temperature difference between adjacent rotor disks. Has been realized.

[0011]

In recent years, gas turbine equipment has been designed to increase energy efficiency and increase power output in response to an increase in power demand in the summer, and to respond to market competition in order to save energy and protect the environment. Cost reduction has been required.

As a means for increasing the efficiency, a high pressure ratio of the compressor tends to be adopted, and as a means for increasing the output, the area of the gas path annular passage is increased by increasing the outer diameter of the rotor of the gas turbine. Tend to be adopted.

As compared with the conventional gas turbine, the working fluid that has been adiabatically compressed by increasing the pressure ratio of the compressor further rises in temperature, and the centrifugal force generated in the rotor disk due to the increase in the annular area of the gas path is reduced. It tends to increase. Therefore, there is a demand for the use of a material having high strength in a high-temperature environment as a rotor disk material.

However, when a high-temperature high-strength material having a higher thermal expansion coefficient and a low-strength material having a lower thermal expansion coefficient are used in combination for the purpose of cost reduction, the difference in thermal expansion in the fitting portion where different materials are combined is used. Because the phenomenon of pushing up and down is more remarkable, excessive thermal stress and centrifugal force are generated by superposition.

Further, even if the material used is the same, between the rotor disks having greatly different circumferential cross-sectional shapes, the phenomenon of raising and lowering due to the difference in thermal expansion and the difference in centrifugal expansion in the fitting portion becomes remarkable, resulting in excessive thermal stress and The centrifugal force is generated by superposition.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems, and in a compressor incorporated in a gas turbine, adjacent portions of a rotor disk made of a different material from each other, and a difference in the shape of the adjacent rotor disks in the radial direction. An object of the present invention is to provide a compressor rotor capable of reducing stress generated at a fitting portion of a rotor disk having a large deformation difference.

[0017]

In order to achieve the above object, the present invention is directed to a rotor, in which a plurality of rotor disks having a plurality of rotor blades mounted on an outer periphery are sequentially arranged from an upstream side of intake air to a downstream side. The disk is provided on one of a radially constrained compressor rotor, an annular hub portion formed on the outer peripheral portion of the rotor disk and closely contacted with the side surface, and one of the rotor disks adjacent along the inner periphery of the annular hub portion. A circular recess, an annular projection provided on the other side of the rotor disk so as to be fitted into the annular projection opposite to the circular recess, and a cross-section formed in the annular projection and having a curvature. It has an inner hole and an arched outer surface.

Thus, the rigidity can be reduced by making the shape of the annular projecting portion into an arch shape consisting of an inner hole based on an R shape having a curvature and an outer surface based on an R shape having a curvature. The contact stress and stress concentration caused by the fitting are reduced.

In the above, it is desirable that the outer surface has a linearly arched shape. Further, the inner hole and a part of the outer surface may be formed into a shape in which the inner hole and a part of the outer surface are cut straight. It is desirable to provide chamfers at the corners of the annular hub and the circular recess.

[0020]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a group of rotor disks of a gas turbine compressor according to an embodiment of the present invention.
FIG. 3 is a sectional view and a side view in the direction of the rotation axis of a single-stage rotor disk. As shown in FIGS. 1 and 4, the rotor blade 9 is fixed by implanting a dovetail 14 provided at a root portion into a dovetail groove 15 provided at an outer peripheral portion of the rotor disk 8. Further, it is preferable that the cross-sectional area of the compressor gas path 4 has a tendency to decrease from upstream to downstream.

The outer peripheral portion of each rotor disk 8 is formed by an annular hub portion 16, and each rotor disk 8 and the adjacent rotor disk 8 are connected to the side surface 17 of the hub portion 16.
Are brought into contact with each other and superimposed. One rotor disk 8
A circular recess 18 (circular inner diameter)
D) is provided, and the hub portion 1 of the other rotor disk 8 'is provided.
6 An annular projection 1 protruding from the hub side surface 17 near the inner circumference.
9 (ring outer diameter d) is provided. The two rotor disks 8, 8 ′ are connected to the circular recess 1 of one rotor disk 8.
8 (circular inner diameter D) is fitted with the annular protrusion 19 (ring outer diameter d) of the other rotor disk 8 ′, whereby the rotor disks 8 ′ are radially restrained from each other.

Further, in the hub portion 16 of each rotor disk 8, the bolt holes 2 having the same radial position from the rotation center axis 20 are provided.
1 is opened, the stacking bolt 22 penetrates therethrough, and both ends are fastened by tightening both ends with the nut 23, and the rotor disk 8 is restrained in the rotation axis direction.

The compressor rotor includes a plurality of rotor blades each of which receives work from a fluid, a plurality of rotor disks in which the rotor blades are implanted along the outer circumference, and which are stacked in multiple stages.
And a stacking bolt that penetrates and fastens the rotor disk. The foremost rotor disk has a rotating shaft extending forward, and the last rotor disk has a rotating shaft extending rearward. The rotor blade has a dovetail that protrudes from both sides from the root of the blade portion, and the rotor disk has a groove formed at an appropriate angle in the rotation axis direction or the circumferential direction on an outer peripheral portion of the rotor disk to fit the dovetail of the rotor blade. Is cut off.

Each rotor disk has a thicker inner peripheral portion than the outer peripheral portion, and forms an annular hub portion on the inner peripheral side near the outer periphery. The side surfaces of the hub portion are brought into close contact with each other and overlapped with the adjacent rotor disk, and the circular recess formed on the side surface of one of the adjacent hub portions and the annular projection formed on the side surface of the other hub portion are fitted by a shaft hole method. I agree. Furthermore, each rotor disk has a group of holes equally spaced from the center axis of rotation in the circumferential direction, and the stacking bolts are respectively passed through the group of holes and fastened through the hub portion. A plurality of stages of rotor disks are stacked and fixed in the axial direction.

As shown in FIG. 1, the rotor disk group 24 disposed upstream of the intake air (on the left side in FIG. 1) and at the front stage where the temperature of the compressed air is relatively low does not require high strength at high temperatures. Therefore, the rotor disk group 25, which is made of a low alloy steel having a small coefficient of thermal expansion and has a somewhat higher temperature of the compressed air and is disposed in the middle and rear stages, has a high high-temperature strength,
Accordingly, it is preferable to use a high alloy material having a large thermal expansion coefficient.

The behavior of a fitting portion between two adjacent rotor disks at the boundary between the rotor disk group 24 and the rotor disk group 25 will be described. At high temperatures, the elongation of the outer ring diameter d of the annular projection 19 on the rotor disk 25 side made of a high alloy material increases the inner diameter D of the circular recess 18 of the low alloy rotor disk 24.
Larger than the elongation. Accordingly, the annular projection 19 is pushed down inward, and stress is generated at the root of the annular projection 19. When the temperature decreases, the state of being pushed down disappears. Therefore, the repetition of the operation / stop of the compressor repeatedly raises and lowers the annular projection 19, which is called a phenomenon of raising and lowering.

In order to suppress the phenomenon of pushing up and down, the annular projection 1
By adopting an arch shape composed of an inner hole 26 based on an R-shape having a curvature and an outer surface 27 based on an R-shape having a curvature as a cross-sectional shape as viewed from the circumferential direction, an annular shape at the fitting portion is obtained. The rigidity of the projection 19 is reduced, and the displacement control type stress generated by the difference between the centrifugal elongation and the thermal elongation is reduced.

The mechanism for reducing the stress will be described with reference to FIG. The left side in the figure is an example of a conventional fitting structure. When an excessive displacement control type load 28 due to the difference in centrifugal elongation and thermal elongation displacement acts on the annular protrusion 19 downward, a high stress concentration occurs at the root corner 29 of the annular protrusion 19, and the circular recess 18 and the annular protrusion Also at the contact surface 30 between the parts 19,
High contact stress occurs.

As shown on the right side of the figure, the stress concentration portion can be eliminated by eliminating the root corner portion 29 and providing the R-shaped inner hole 26 having a curvature. In addition, the annular protrusion 19
Outer surface 2 based on R-shape having its own curvature
7, the displacement control type load 2
8, the contact stress at the contact surface 30 between the circular recess 18 and the annular projection 19 is reduced.

FIG. 6 shows another embodiment. As shown in the figure, of the two adjacent rotor disks, the annular projection 19 has a cross-sectional shape as viewed from the circumferential direction, and has an R shape having a curvature. By adopting an arch shape consisting of a basic inner hole 26 and an outer surface 27 based on an R-shape having a curvature, an annular projection portion in a fitting portion is provided by providing a straight portion 31 in a part of the inner hole 26. 19, the displacement control type stress generated due to the difference between the centrifugal elongation and the thermal elongation is reduced, and the processing is facilitated.

FIG. 7 shows still another embodiment. As shown in FIG. 7, of the two adjacent rotor disks, the annular projection 19 has a sectional shape viewed from the circumferential direction.
The adoption of an arch shape consisting of an inner hole 26 based on an elliptical shape and an outer surface 27 based on an R shape having a curvature reduces the rigidity of the annular projection 19 in the fitting portion,
The displacement control type stress generated by the difference between the centrifugal elongation and the thermal elongation is reduced.

FIG. 8 shows still another embodiment. As shown in FIG.
As the cross-sectional shape of the annular projection 19 viewed from the circumferential direction, an arch shape including an inner hole 26 based on an elliptical shape and an outer surface 27 based on an R shape having a curvature is adopted. By providing the linear portion 31 in the portion, the rigidity of the annular protrusion 19 in the fitting portion is reduced, the stress of the displacement control type generated due to the difference between the centrifugal elongation and the thermal elongation is reduced, and the processing is facilitated.

[0033] Figure 9 is a another embodiment in the et, of two front and rear stage rotor disk adjacent as shown in FIG,
The annular projection 19 at the fitting portion is formed by adopting an arch shape composed of an inner hole 26 based on an R shape having a curvature and an outer surface 27 based on a straight line as a cross-sectional shape of the annular projection 19 viewed from the circumferential direction. The rigidity of the portion 19 is reduced, and the displacement control type stress caused by the difference between the centrifugal elongation and the thermal elongation is reduced.

FIG. 10 shows still another embodiment. As shown in FIG. 10, of the two adjacent front and rear rotor disks, the annular projection 19 has a cross-sectional shape viewed from the circumferential direction, and has an R-shape having a curvature. In addition to adopting an arch shape composed of an inner hole 26 based on a straight line and an outer surface 27 based on a straight line, the rigidity of the annular projection 19 in the fitting portion is obtained by providing a straight portion 31 in a part of the inner hole 26. , And the stress of the displacement control type generated by the difference between the centrifugal elongation and the thermal elongation is reduced, and the working becomes easy.

FIG. 11 shows still another embodiment.
As shown in the figure, a chamfer 33 of 1/7 or more of the length of the concave portion of the circular concave portion 18 is provided at the corner 32 where the annular hub portion 16 and the circular concave portion 18 intersect among the adjacent two-stage rotor disks. The circular recessed part 1 in the fitting part
8, the displacement control type stress generated by the difference between the centrifugal elongation and the thermal elongation is reduced. The chamfer in the seventh embodiment may be a corner R. In each of the above embodiments, a corner R may be provided at each corner for convenience in manufacturing.

As described above, the phenomenon of pushing up due to the difference in thermal expansion near the dissimilar material contact portion is sufficiently suppressed, and the stress generated in the rotor disk is reduced.

[0037]

According to the present invention, the cross-sectional shape of the annular projection as viewed from the circumferential direction has an inner hole based on an R shape having a curvature and an arch shape formed of an outer surface based on an R shape having a curvature. By doing so, the rigidity can be reduced, and the stress generated by the displacement control type load due to the fitting can be reduced.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a structure of a compressor rotor according to an embodiment of the present invention.

FIG. 2 is a sectional view showing a structure of a general gas turbine.

FIG. 3 is a cross-sectional view showing a structure of a conventional turbine rotor that eliminates a difference in thermal expansion.

FIG. 4 is a cross-sectional view showing the structure of a single-stage rotor disk according to one embodiment.

FIG. 5 is a cross-sectional view illustrating a mechanism of a load acting on a fitting portion of the rotor disk.

FIG. 6 is a sectional view showing a structure of a fitting portion according to another embodiment.

FIG. 7 is a sectional view showing a structure of a fitting portion according to another embodiment.

FIG. 8 is a sectional view showing a structure of a fitting portion according to another embodiment.

FIG. 9 is a cross-sectional view showing a structure of a fitting portion according to another embodiment.

FIG. 10 is a cross-sectional view showing a structure of a fitting portion according to another embodiment.

FIG. 11 is a cross-sectional view showing a structure of a fitting portion according to another embodiment.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 compressor 2 combustor 3 turbine 4 gas path 5 foremost rotor disk 6 last stage rotor disk 7 intermediate stage rotor disk 8 rotor disk 9 rotor blade 10 stationary blade 11 shroud 12 spacer 13 bolt hole 14 dovetail 15 dovetail groove 16 annular hub 17 Hub Side Surface 18 Circular Depression 19 Annular Projecting 20 Rotation Center Shaft 21 Stacking Bolt Hole 22 Stacking Bolt 23 Nut 24 Front Rotor Disk 25 Rear Rotor Disk 26 Inner Hole 27 Outer Surface 28 Displacement Control Type Load 29 Root Corner 30 Contact surface 31 Linear part 32 Tolerance corner part 33 Chamfer

──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Yasuhiro Kato 7-2-1, Omika-cho, Hitachi City, Ibaraki Prefecture Hitachi, Ltd. Electric Power & Electric Equipment Development Division (58) Field surveyed (Int. Cl. ⁷ , DB Name) F04D 29/34

Claims (4)

(57) [Claims] 1. A plurality of rotor disks Installing a plurality of rotor blades on the outer periphery are sequentially disposed downstream from the upstream side of the intake air, the compressor rotor the rotor disks are constrained in the radial direction, the rotor An annular hub portion formed on the outer peripheral portion of the disk and closely contacting the side surface; a circular recess provided on one of the adjacent rotor disks along the inner periphery of the annular hub portion; An annular protrusion provided to be fitted into the circular recess in opposition to the circular recess , an inner hole formed in the annular protrusion and having a cross-sectional shape having a curvature, and an arch shape; A compressor rotor having an outer surface. 2. The compressor rotor according to claim 1, wherein said outer surface has a linearly arched shape. 3. The compressor rotor according to claim 1, wherein said inner hole and a part of said outer surface are cut off linearly. 4. The compressor rotor according to claim 1, wherein a chamfer is provided at corners of said annular hub and said circular recess.