JPH04134605U - steam turbine rotor blades - Google Patents

Abstract

(57) [Summary] [Purpose] The purpose is to reduce damage to the blade root. [Structure] A relief is formed on the ventral surface of the blade outlet of the blade root of a rotor blade of a steam turbine that is fixed to a groove of a rotor via the blade root.

Description

[Detailed explanation of the idea]

0001

[Industrial application field]

The present invention relates to rotor blades for steam turbines applied to thermal power generation and the like.

0002

[Conventional technology]

The rotor blades of a steam turbine are shaped like a Christmas tree due to centrifugal force acting on the blades. Various types of blade root shapes are used, including letter-shaped, dovetail-shaped, and sawtooth-shaped. Figure 2 1 is a structural explanatory diagram of a rotor blade of a conventional steam turbine. In the figure, the main rotor blade is It has a mass tree-shaped blade root 1, and a rotor (not shown) is connected via this blade root 1. is fixed in the groove. Steam flows through the blade profile 2 in the direction indicated by arrow d. Ru.

0003

[Problem that the idea aims to solve]

In the rotor blades of conventional steam turbines as described above, the rotor blades are subject to centrifugal force due to rotation. and the bending force caused by the steam acts, and these forces are transmitted to the rotor via the blade root 1. Ru. Therefore, vibration stress that changes periodically along with static stress is generated in the blade root 1. Ru. In general, as shown in the figure, the rotor blades of a steam turbine have a blade profile section 2 at the outlet. The blade is curved toward the ventral side, and its centrifugal force is applied to the wing profile on platform 3. 2 Eccentric to the trailing edge side. This eccentric centrifugal force is caused by arrow e on platform 3. The moment becomes as shown below, increasing the surface pressure on the ventral side of the blade outlet at the blade root 1. let If this local surface pressure becomes excessive, the ventral side of the blade outlet of the blade root 1 will be damaged. .

0004

[Means to solve the problem]

The purpose of the rotor blade of the evaporator turbine according to the present invention is to solve the above problems. In steam turbine rotor blades that are fixed to the grooves of the rotor through It is characterized by a relief formed on the ventral side of the outlet.

[0005]

[Effect]

That is, in the steam turbine rotor blade according to the present invention, the rotor is connected to the rotor through the blade root. Relief on the ventral side of the blade outlet of the blade root of a steam turbine rotor blade that is fixed in a groove. is formed, and the blade root of the rotor blade, which is in pressure contact with the rotor groove, is compressed by external force. The blade is elastically deformed and excessive stress is applied locally to the surface of the blade root on the ventral side of the blade outlet. The leaves remove this locally excessive stress, making it almost uniform over the entire width of the blade root. become.

[0006]

【Example】

FIG. 1 is a structural explanatory diagram of a rotor blade of a steam turbine according to an embodiment of the present invention. In the figure The rotor blades of the steam turbine according to this embodiment are steam turbines used for thermal power generation. This rotor blade has a Christmas tree-shaped blade root 1 as shown in the figure. It is fixed to a groove of a rotor (not shown) via the root 1. Steam is indicated by arrow d. flow through the blade profile 2 in the direction of the flow. The rotor blades are caused by centrifugal force due to rotation and steam Bending forces act and these forces are transmitted via the blade root 1 to the rotor. For this reason , a periodically changing vibration stress is generated in the blade root portion 1 along with static stress. Also, one Generally speaking, the rotor blades of a steam turbine have a blade profile portion 2 facing toward the ventral side of the outlet end, as shown in the figure. The centrifugal force is biased toward the trailing edge of the blade profile 2 on the platform 3. I care. This eccentric centrifugal force is generated by a motor as shown by arrow e on platform 3. This increases the surface pressure on the surface A of the blade root 1 on the ventral side of the blade outlet. This local If the surface pressure becomes excessive, the ventral side of the blade outlet of the blade root 1 will be damaged, so in this rotor blade, The surface A on the ventral side of the blade outlet of the blade root 1 where the surface pressure locally increases is cut thinly and removed. A relief is formed to release excessive surface pressure. This relief is formed The width b is 1/5 or less of the total width B of the blade root 1, and its depth is the surface C where no relief is formed. It increases linearly starting from the boundary with 10/100 to 20 at the edge of blade root 1. /100mm.

[0007] By forming a relief on the surface A of the blade outlet ventral side of the blade root 1 in this way, , the surface pressure acting locally on the surface A on the ventral side of the blade outlet of the blade root 1 is released, causing excessive stress. is removed and acts almost uniformly over the entire width B of the blade root 1, so the blade Damage at the root 1 is reduced and the life of the rotor blade is increased.

[0008]

[Effect of the idea]

The rotor blades of the steam turbine according to the present invention are constructed as described above, and the rotor blades are formed at the blade roots. Since the applied stress is almost uniform across the entire width of the blade root, damage to the blade root is minimized. Reduced.

[Brief explanation of drawings]

FIG. 1 is a perspective view of a rotor blade of a steam turbine according to an embodiment of the present invention.

FIG. 2 is a perspective view of a rotor blade of a conventional steam turbine.

[Explanation of symbols]

1 Wing root 2 Wing profile part 3 Platform A Ventral surface of the blade outlet at the blade root B Total width of wing root b Width forming relief C Surface that does not form relief

Claims (1)

[Scope of utility model registration request] 1. A rotor blade for a steam turbine fixed to a groove of a rotor via a blade root, wherein a relief is formed on a surface of the blade root on the ventral side of a blade outlet.