JPH06129203A - Vibration suppressing structure for gas turbine rotor blade - Google Patents

Abstract

PURPOSE:To provide a blade vibration suppressing structure which can cope with an increase in the height of a blade caused by an increase in the temperature of a gas turbine. CONSTITUTION:A vibration suppressing structure for a gas turbine blade comprises a platform 14, a shank and a blade root 16 which are arranged in that order and which are integrally incorporated with the lower part of a blade profile part 12. A part 17 making press-contact with a circumferential end surface of an adjacent blade platform is formed on a circumferential end surface of the platform 14 so that the surface pressure is generated at the press contact part 17 by twist-back during operation in order to form a group of blades. Thereby it is possible to eliminate the necessity of formation of a shroud in the upper part of the blade profile part 12.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas turbine rotor blade, particularly to a gas turbine rotor blade having a long shank portion or a large ratio of the shank portion length to the blade total length, and to an optimum vibration damping structure.

[0002]

2. Description of the Related Art A gas turbine rear-stage rotor blade is fatigued and broken when the blade lengthens and the frequency decreases, and when the blade natural frequency matches or is close to the harmonics of the turbine speed. Therefore, as a countermeasure against this, conventionally, an integral shroud blade is used as a gas turbine blade.

FIG. 3 shows a conventional integral shroud blade 1
In the perspective view of FIG. 2, a shroud 3 is integrally formed on the upper portion of the blade profile portion 2, and a platform 4, a shank 5 and a blade root 6 are sequentially formed integrally on the lower portion of the blade profile portion 2. The shroud wing 1 is configured. Then, the cooling air flows on the side surface of the shank 5, and the portion of the blade root 6 having a high stress is prevented from reaching a high temperature.

Next, FIG. 4 is a plan development view of the shroud portion taken along the line IV-IV of FIG. 3, in which the pressure contact portion 7 with the adjacent blade shroud 3'is provided on the circumferential end surface of the shroud 3. . In this, the center of gravity line of the integral shroud blade 1 in the height direction is shifted in advance, and when the rotor rotates, torsional moments in the directions A and B of the arrows are generated to press the portion indicated by reference numeral 7 into pressure contact. At this time, the adjacent blades form a group blade and have a high natural frequency, and a damping structure improves the vibration resistance. This structure is generally
It is called a twist back structure.

[0005]

By the way, recently, the length l of the shank 5 of the integral shroud blade 1 is gradually increased with the increase in the temperature and the capacity of the gas turbine, and the cooling effect is increased. Has been. Further, in the future, there is a great possibility that the shank 5 portion will be longer due to the convenience of the cooling air or the like.

As described above, recently, the blade height tends to increase as the temperature and the capacity of the gas turbine increase, but the conventional integral shroud blade 1 shown in FIGS. 3 and 4 is used. In this case, the wall thickness of the shrouds 3, 3'is relatively thin with respect to the magnitude of the centrifugal force applied to the moving blade. Therefore, the centrifugal force and the twist back cause the shrouds 3 and 3'to be turned up, and the stress and the decrease in the vibration absorbing force become a problem as the blade height increases as the gas turbine temperature increases and the capacity increases. It has become to.

The present invention has been made in order to solve the problems of the prior art as described above, and a rotor blade anti-vibration structure capable of sufficiently coping with an increase in blade height due to an increase in temperature and capacity of a gas turbine. The purpose is to provide.

[0008]

In order to solve the above-mentioned problems, the present invention provides a vibration isolating structure for a gas turbine blade in which a platform, a shank, and a blade root are integrally formed in a lower portion of a blade profile section in order. A pressure contact portion with an end surface of an adjacent blade platform is provided on a circumferential end surface of the platform, and a surface pressure is generated at the pressure contact portion during operation by a twist back to form a group blade.

[0009]

According to the above means, a pressure contact portion with the end face of the adjacent blade platform is provided on the circumferential end surface of the platform thicker than the shroud, and the surface pressure is applied to the pressure contact portion during operation by the twistback. Since they are generated to form a group wing, there is no turning up of the platform as in the case of a shroud.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to FIGS. FIG. 1 is a perspective view showing an example of a gas turbine rotor blade embodying the present invention, and FIG. 2 is II- of FIG.
It is a plane development view of the platform part which follows the II line.

In FIG. 1, a gas turbine moving blade 11 includes a blade profile portion 12, and a platform 14, a shank 15 and a blade root 16 are integrally formed in the lower portion of the blade profile portion 12 in order.

According to the present invention, as best shown in FIG. 2, a pressure contact portion 17 with an adjacent wing platform 14 'is provided on the circumferential end surface of the platform 14. The center of gravity of the gas turbine rotor blade 11 in the height direction is displaced in the same manner as in the prior art, and a twisting moment is generated in the arrow directions A and B by the rotation of the rotor, so that the pressure contact portion 17 is brought into contact with the pressure contact portion 17 by twist back. Pressure is generated to form group wings.

That is, according to the present invention, as described above, the length l of the shank 15 of the gas turbine rotor blade 11 has been gradually increased due to the enhancement of cooling accompanying the increase in temperature and the increase in capacity of the gas turbine. In view of the above, it is noted that it is sufficiently possible to fix the blade root 16 and torsionally deform the platform 14 in the recent gas turbines, and the circumferential end face of the platform 14 and the end face of the adjacent blade platform 14 ′ are connected to each other. A pressure contact portion 17 is provided, and the pressure contact portion 17 is pressure contacted by a twisting moment due to a twist back to form a group blade.

Since the platforms 14 and 14 'are thicker than the shroud, the turning up unlike the case of the shroud does not occur. Also, the shroud can be eliminated and a low-cost freestanding long wing can be obtained.

[0015]

As described above, according to the present invention, in the vibration isolating structure of the gas turbine blade in which the platform, the shank, and the blade root are integrally formed in the lower portion of the blade profile portion, the thickness is larger than that of the shroud. A thick contact platform is provided on the circumferential end face of the adjacent blade platform with a pressure contact part with the end face of an adjacent wing platform, and a twist wing is used to generate a surface pressure on the pressure contact part during operation to form a group wing. Therefore, it is possible to provide a rotor blade vibration isolating structure capable of sufficiently dealing with the increase in blade height due to the recent increase in temperature and capacity of gas turbines, unlike the case of a shroud.

Further, according to the present invention, since the shroud can be eliminated, the gas turbine long blade, which has conventionally used the integral shroud blade of high cost, can be replaced with the free standing blade of low cost without changing the vibration resistance strength. Since it can be modified and there is no shroud,
The problem of turning up does not occur and reliability is improved.

[Brief description of drawings]

FIG. 1 is a perspective view showing an example of a gas turbine rotor blade embodying the present invention.

FIG. 2 is a plan development view of a platform portion taken along the line II-II in FIG.

FIG. 3 is a perspective view showing a conventional gas turbine rotor blade.

FIG. 4 is a plan development view of a shroud portion taken along line IV-IV in FIG.

[Explanation of symbols]

 11 Gas Turbine Blade 12 Blade Profile Section 14 Platform 14 'Adjacent Blade Platform 15 Shank 16 Blade Root 17 Pressure Contact Section

Claims (1)

[Claims] 1. A vibration isolating structure for a gas turbine rotor blade, in which a platform, a shank and a blade root are integrally formed in a lower portion of a blade profile portion, and a circumferential end face of the platform is press-contacted with an end face of an adjacent blade platform. Is provided
A vibration isolation structure for a gas turbine rotor blade, wherein a surface pressure is generated in the pressure contact portion during operation by a twistback to form a group blade.