JPH0415922Y2 - - Google Patents

Description

[Detailed description of the invention] [Field of industrial application] The present invention relates to a gas turbine having ceramic rotor blades, and particularly relates to a gas turbine having ceramic rotor blades with an improved coupling method between the rotor blades and the impeller. .

[Prior Art] Gas turbines using ceramic rotor blades, which have excellent strength and corrosion resistance at high temperatures, have been extensively researched in recent years.

As a method of attaching this ceramic rotor blade to a metal impeller, a method is known in which a recess is formed in the circumferential surface of the impeller and a rotor blade having a blade root shaped to fit into the recess is fitted. be. (For example, Journal of the Gas Turbine Society 7-28, p. 54, 1980) [Problems to be solved by the invention] As is well known, ceramic is a brittle material, so as mentioned above, ceramic is a brittle material. If the blade is fitted into the recess of the blade wheel, when an impact load is applied to the rotor blade, a large stress is locally applied to the root of the blade, which may cause cracks or the like to occur in the root of the blade.

[Means for Solving the Problems] As shown in FIGS. 1 and 3, the gas turbine of the present invention has a shank member 3 for holding rotor blades 4 on the circumferential surface of the blade wheel 1. A large number of them are fixed at predetermined intervals in the circumferential direction. Then, a ceramic rotor blade 4 is attached to this shank member 3 with bolts 8, and a metal material (hereinafter referred to as "superplastic alloy") that exhibits superplasticity at the temperature of the attachment part of the rotor blade member during gas turbine operation. ) 5 is interposed on the contact surface with the shank member 3.

Generally, when a gas turbine is operated, the rotor blades and the impeller are heated by the combustion gas, and the temperature of the rotor blade attachment area is also high. By using ceramic rotor blades, the gas turbine of the present invention can use combustion gas at a higher temperature as a working fluid than in conventional gas turbines that use metal rotor blades. Therefore, the temperature of the rotor blade attachment portion during gas turbine operation has a wider range of temperatures than in conventional gas turbines. In this invention, the temperature of the rotor blade attachment part during gas turbine operation is normally
The temperature ranges from 500 to 1200℃.

An example of a metal material that exhibits superplasticity at the temperature of the rotor blade attachment portion during gas turbine operation is shown below.

Alloy name Superplastic temperature (℃) Nickel 39/10Fe/1.75Ti/1Al 900 Nickel 39/8Fe/2Ti/1Al 980 Copper/10−20Mg 700 Copper/10−12Al 540 Copper/10Al/4Fe 830 Inconel 744X 980 IMI318 Titanium /6Al/4V 900~980 IMI318 Titanium/5Al/2.5Sn 1000 IMI679 Titanium/11Sn/2.25Al/10Mo/5Zr/
0.12Si 800 IMI700 Titanium/6Al/5Zr/4Mo/1Cu/0.25Si
800 Such a superplastic alloy can be interposed on the rotor blade contact surface by the following method.

After coating the surfaces of the moving blade 4, shank member 3, or impeller 1 with a superplastic alloy by a method such as wet plating, thermal spraying, melt plating, or blast bonding, the moving blade 4 is bonded to the shank member 3 and the impeller 1. Fits into the enclosed part.

Note that the wet plating method is a method of electrically plating using an aqueous solution.

Thermal spraying is a method in which metal is melted using a high-temperature flame or electric arc, atomized by compressed air, and then sprayed onto a mating member for adhesion.

The hot-melt plating method is a method of depositing a thin metal film on the surface of a member by bringing molten metal into contact with the material.

The blast bonding method is a method in which a superplastic material powder is subjected to blast processing, and the superplastic flow at that time is utilized to quickly cover the powder with pressure bonding.

When the rotor blade 4 is fitted into the part surrounded by the shank member 3 and the impeller 1, a sheet-like or powder-like superplastic alloy is sandwiched between the rotor blade 4 and the shank member 3.

In the present invention, silicon nitride, silicon carbide, sialon, etc. are suitable as the ceramic.

In addition, the shank member 3 is made of Fe-based, Co-based, Ni
It is made of an alloy with high temperature strength, corrosion resistance, etc.

[Function] Since the superplastic alloy 5 is interposed on the contact surface between the rotor blade 4 and the shank member 3, this superplastic alloy 5 exhibits a vibration damping effect and also The contact with 1 is uniform and soft. Furthermore, even if an impact load is applied to the rotor blade 4, local stress concentration does not occur at the root portion 4b of the rotor blade 4.

Furthermore, since the ceramic rotor blade 4 and the metal shank member 3 are not in direct contact with each other, stress caused by the difference in expansion between the rotor blade 4 and the shank member 3 is alleviated.

[Examples] Examples will be described below with reference to the drawings.

1 and 3 show an embodiment of the present invention, with FIG. 1 being a cross-sectional view in a direction including the axis of the impeller 1, and FIG. 3 being a perspective view.

As shown in FIG. 3, groove-shaped recesses 2 extending in the axial direction of the impeller 1 are provided on the circumferential surface of the impeller 1 at predetermined intervals. In this embodiment, the recess 2 has a Christmas tree shape in which the opening of the circumferential surface of the impeller and three portions in the groove depth direction are constricted.

A shank member 3 having a Christmas tree-shaped root portion 31 that fits into the recess 2 is fixed by fitting the root portion 31 into the recess 2.

A moving blade 4 made of ceramics is attached to the top surface 3b of this shank member 3.

Next, the configuration of the shank member 3 and the mounting portion of the rotor blade 4 will be explained with reference to FIG. 1.

The shank member 3 has a substantially rectangular parallelepiped shape, and a Christmas tree-shaped root portion 31 is formed at the bottom thereof, as described above. Seal fins 33 to 36 are provided on the front and rear surfaces, that is, on the side surfaces in the blade axle direction, for preventing combustion gas from flowing into the blade wheel. Note that the surface of this shank member 3 is coated with ceramic.

A recess 37 having a shape into which the rotor blade 4 fits is formed in the top surface 32 of the shank member 3, and a cooling air circulation hole 38 is bored in the bottom surface. Furthermore, bolt insertion holes 39 are provided in the vertical direction in the figure, that is, in the radial direction of the impeller.

The rotor blade 4 is a sectional view taken along the line in FIG. 1. As shown in FIG. 2, it has a curved airfoil cross section and is provided with a deep cavity 41. A bolt insertion hole 49 is provided at the bottom of the cavity 41 so as to be coaxial with the bolt insertion hole 39 of the shank member. The rotor blade 4 is fitted into the recess 37 of the shank member 3 with a plate-shaped superplastic alloy 5 interposed therebetween.

Further, a plate-shaped superplastic alloy 6 and a washer 7 are inserted into the bottom surface of the rotor blade cavity 41, and the bolt 8 is inserted into the washer 7, the superplastic alloy 6, and the bolt insertion hole 49,
39 is inserted. A nut 9 is fitted to the tip of the bolt 8 (lower end in the figure), and the rotor blade 4 is fixed to the shank member 3 by the bolt 8 and nut 9. In the figure, 10 is a washer interposed on the contact surface of the nut 9. These superplastic alloys 5 and 6 provide vibration damping effects, stress dispersion, and
Effects such as relaxation are produced.

In particular, in this embodiment, since the superplastic alloy 6 is also interposed between the washer 7 and the rotor blade 4, it is even more effective.

In this embodiment, the surface of the shank member 3 is coated with ceramic, and the surface of the shank member 3 is coated with ceramic.
Made of heat-resistant material and has high corrosion resistance.

In this embodiment, the bolt 8 is inserted from the rotor blade 4 toward the shank member 3, but it may be inserted from the shank member 3 toward the rotor blade 4 conversely.

[Effects] As described above, in the gas turbine of the present invention,
Since the superplastic alloy is interposed at the contact surface between the rotor blade and the shank member, a vibration damping effect is exhibited, and the contact of the rotor blade with the shank member becomes uniform and soft. Therefore, even if an impact load is applied to the rotor blade, stress concentration does not occur at the rotor blade attachment portion. Therefore, the durability of the rotor blade is significantly increased.
In addition, the shape of the rotor blades can be simple, and therefore the manufacturing cost is low.

Stress caused by the difference in thermal expansion between the rotor blade and the shank member is alleviated.

Since the shank member is attached to the impeller by fitting the metal members together, the shank member has sufficient strength.

The rotor blades are made of highly heat-resistant ceramic, so less cooling air is needed.

It has excellent technical features such as

[Brief explanation of the drawing]

1 and 3 are diagrams showing the rotor blade and shank member of a gas turbine according to an embodiment of the present invention, FIG. 1 is a sectional view in a direction including the axis of the impeller, and FIG. 3 is a perspective view. It is a diagram. Moreover, FIG. 2 is a sectional view of the rotor blade. DESCRIPTION OF SYMBOLS 1... Impeller, 3... Shank member, 4... Moving blade, 5, 6... Superplastic alloy, 8... Bolt, 9...
...Natsuto.

Claims (1)

[Scope of Claim for Utility Model Registration] (1) A gas turbine in which a metal shank member is attached around a blade wheel, and a ceramic rotor blade is attached to the top surface of the shank member with bolts, during gas turbine operation. A gas turbine having a ceramic rotor blade, characterized in that a metal material exhibiting superplasticity at the temperature of the rotor blade attachment portion is interposed at the contact surface between the rotor blade and the shank member. (2) The bolt is in contact with the rotor blade through a washer, and the contact surface between the washer and the rotor blade is interposed with a metal material that exhibits superplasticity at the temperature of the rotor blade attachment part. A gas turbine having ceramic rotor blades as claimed in claim 1.