JPH07233703A - Shroud for gas turbine moving blade - Google Patents

Abstract

PURPOSE:To realize a shape without causing deformation due to creep in the base part of a moving blade shroud even when a gas turbine has high temperature and large output. CONSTITUTION:In the shape of a shroud 3, provided on the tip 2 of the moving blade profile part 1 of a gas turbine and a fillet 4 is attached to a lower surface side; a fillet 5 is attached to also the upper surface side of the shroud 3. The fillet 4 fitted to the lower surface side of the shroud 3 is formed of an elliptical long arc R. Moreover, the abutting surface 6 of the shroud 3 of an adjoining moving blade is made partial abutting.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the shape of a shroud provided on a tip of a gas turbine blade.

[0002]

2. Description of the Related Art Gas turbines and combined cycle power plants using the gas turbines are required to have high temperatures and high output in order to improve thermal efficiency. Along with that, we are focusing on studying the strength and shape of the blades, adopting forced cooling blades, and improving the heat resistance strength of the materials. Further, the shape of the shroud provided on the tip of the moving blade is also affected by the increase in temperature and output of the gas turbine.

FIG. 3 is a side view showing a shroud of a conventional gas turbine rotor blade. In FIG. 3, a shroud 3 is cut on the tip 2 of the rotor blade profile portion 1 in order to prevent gas overflow and individual vibration of the blade. A fillet 4 having a radius R is cut on the lower surface side of the shroud 3. The fillet 4 is formed as a reinforcement for reducing the turning-up stress. Further, on the upper surface side of the shroud 3, shroud fins 7 that reinforce the shroud 3 are cut.

[0004]

In the conventional rotor blade shroud shown in FIG. 3, the temperature and stress at the root of the rotor blade shroud increase as the gas turbine temperature increases and the power output increases. Deformation due to creep occurs before the time elapses.

FIG. 4 is a diagram showing the action of turning-up stress of a conventional gas turbine rotor blade. As shown in FIG. 4, when the gas turbine rotor blade rotates while the gas turbine temperature is high and the power output is high, turning stress is applied in the direction of the arrow, and the root portion of the rotor blade shroud is significantly deformed. ,
It has the effect of shortening the life by creep.

As described above, in the conventional gas turbine moving blade, the deformation of the blade shroud root due to creep occurs as the temperature and temperature of the gas turbine increase, and the blade must be replaced or repaired. ing. Also,
Not only that, but it may cause troubles such as vibration, contact, and performance degradation.

The present invention has been made in order to solve the above-mentioned problems of the prior art. Even if the gas turbine is heated to a high temperature and has a large output, the root of the blade shroud is not deformed due to creep. An object is to provide a shaped gas turbine blade shroud.

[0008]

SUMMARY OF THE INVENTION In order to solve the above problems, the present invention provides a shroud provided on a tip of a gas turbine blade and having a fillet on the lower surface side, in which the upper surface side of the shroud It also has a fillet. Further, a fillet attached to the lower surface side of the shroud is formed by an elliptical long arc.
Further, the contact surfaces of the shrouds of the adjacent moving blades are partially contacted.

[0009]

According to the above-mentioned means, since the fillet is provided on the upper surface side of the blade shroud, the turning stress of the shroud is reduced.

Further, by forming the fillet attached to the lower surface side of the blade shroud with an elliptical long arc, the R portion of the fillet becomes smoother, lighter than the conventional R, and the turning-up stress is reduced. .

Further, since the contact surfaces of the adjoining blade shrouds are partially contacted and the contact surfaces have a thickness capable of ensuring the minimum necessary area, the area required for vibration prevention can be ensured and the weight can be reduced.

[0012]

Embodiments of the present invention will be described in detail below with reference to FIGS. 1 is a side sectional view showing an embodiment of a shroud of a gas turbine blade according to the present invention, and FIG. 2 is an enlarged plan view of FIG.

As shown in FIGS. 1 and 2, according to the present invention, a shroud 3 is cut in the tip 2 of the profile portion 1 of the gas turbine rotor blade. On the lower surface side of the shroud 3, a fillet 4 having an elliptical shape, for example, a horizontally long quarter elliptical long arc R is cut. Further, a fillet 5 having a radius R ′ is cut on the upper surface side of the moving blade shroud 3. The contact surface 6 of the adjacent blade shroud 3 is partially provided with a thickness that can secure a minimum necessary area for vibration. Reference numeral 7 is a shroud fin.

According to the shape of the shroud of the gas turbine moving blade described above, the turning-up stress of the shroud 3 is reduced by providing the fillet 5 also on the upper surface side of the moving blade shroud.

Further, by forming the fillet 4 attached to the lower surface side of the rotor blade shroud 3 with an elliptical long arc, the R portion of the fillet becomes smoother, and the conventional R
Compared with, the weight is lighter and the turning stress is reduced.

Further, the contact surface 6 of the adjoining blade shroud 3 is partially contacted, and the contact surface has a thickness capable of ensuring the minimum necessary area, so that the necessary area for vibration prevention can be ensured and the weight can be reduced. it can.

[0017]

As described above, according to the shroud shape of the gas turbine rotor blade of the present invention, it is possible to reduce the stress at the root portion of the rotor blade shroud even when the gas turbine has high temperature and high output. The creep life due to temperature and stress can be extended to the target life. Therefore, the effect that the reliability of the gas turbine can be improved and the maintenance cost can be reduced by replacement, repair, etc. is extremely large.

[Brief description of drawings]

FIG. 1 is a side sectional view showing an embodiment of a shroud of a gas turbine blade according to the present invention.

FIG. 2 is an enlarged plan view of FIG.

FIG. 3 is a side view showing a shroud of a conventional gas turbine blade.

FIG. 4 is a diagram showing an action of turning stress in a conventional gas turbine rotor blade.

[Explanation of symbols]

 1 blade profile 2 tip 3 shroud 4 lower fillet 5 upper fillet 6 contact surface of adjacent shroud 7 shroud fin

Claims (3)

[Claims] 1. A shroud for a gas turbine blade, wherein the shroud is provided on the tip of the gas turbine blade and has a fillet on the lower surface side, and a fillet is also provided on the upper surface side of the shroud. . 2. A shroud for a gas turbine rotor blade according to claim 1, wherein a fillet attached to a lower surface side of the shroud is formed by an elliptical long arc. 3. A shroud for a gas turbine blade according to claim 1, wherein the contact surface of the shrouds of adjacent blades is a partial contact.