JPH10231702A - Shroud-integrated steam turbine blade - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a vibration characteristic during operation from largely changing in fluctuation of an operating condition caused by a special arrangement relation of a shroud by arranging a half-round projection on one end of a circumferential direction of the shroud, and a half-round groove which is brought into linear contact with the projection of the shroud located adjacently to the other end. SOLUTION: A small half-round projection 6 is arranged on one end of a circumferential direction of one shroud 5 formed integratedly with blades 1, 2, and is joined with a small half-round groove 7 provided on the end opposed to the other shroud 5 located adjacently thereto. In the case where the shrouds 5 which are located adjacently to each other are brought into linear contact with each other on a line located on a circumferential surfaces of the groove 7 and the projection 6 and are formed as a ring blade structure along all circumferences, restriction condition of the shroud 5 is held in a nearly constant level so as to prevent change even if contact reaction between the shrouds 5 is changed by change of an operating condition, and thereby, the frequency is almost not changed. A blade frequency is regulated in a design step so as to avoid resonance of the number of a stationary blade and the number of a stay surely.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a steam turbine blade having a configuration applicable to a gas turbine blade and a compressor blade.

[0002]

2. Description of the Related Art A conventional T root integral shroud blade will be described with reference to FIG.

[0003] Reference numeral 1 denotes a wing, and 2 denotes another adjacent wing.
Each extends from above the platform 3 and has a root portion as a T root blade root 4.

The wings 1 and 2 each have a shroud 5 integrally formed on the top thereof, and the side surfaces of the shroud 5 are machined in parallel with the radial line. Surface contact is made at the surface 5a.

[0005]

In the above-described conventional shroud blade structure, the adjacent shrouds 5 are in surface contact with each other at the contact surface 5a, so that the shroud blades may not be connected to each other due to a change in operating conditions such as the rotation speed and temperature of the turbine. When the contact reaction force changes from the state of the full-circle ring blade characteristic (solid line A) in which the shroud is strongly restricted as shown in FIG. The frequency greatly changes between the states of B).

Further, if a gap is formed between the shrouds during operation, the vibration frequency is reduced to the state of the single blade vibration characteristic (dot-dash line C) in which the shroud is not restricted. For this reason, it is very difficult to adjust the blade frequency, and resonance may occur with the number of stationary blades or the number of stays under specific operating conditions, which may cause troubles such as blade damage.

The present invention solves such a problem in the prior art, and is not significantly affected by fluctuations in operating conditions due to the special arrangement of adjacent shrouds, so that the vibration characteristics change greatly during operation. It is an object of the present invention to provide an apparatus that prevents such a situation.

[0008]

SUMMARY OF THE INVENTION The present invention has been made in order to solve the above-mentioned problems, and a semicircular projection is provided at one end of a shroud of a shroud-integrated steam turbine blade in a circumferential direction. A shroud-integrated steam turbine blade provided with a semi-circular groove in line contact with said protrusion of the adjacent shroud, wherein adjacent shrouds mutually have a semi-circular protrusion of one shroud and a half of the other shroud. Because it is arranged so that the circular groove makes line contact,
Even if the operating conditions of the turbine change and the contact reaction force between adjacent shrouds increases, due to this line contact, the rotational displacement of the shroud around the radial axis is hardly constrained, and the frequency remains almost unchanged. Resonance can be reliably avoided.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described with reference to FIGS. Note that the same parts as those of the above-described conventional one are denoted by the same reference numerals in the drawings, and redundant description will be omitted.

That is, in the present embodiment, a small semicircular protrusion 6 is provided at one circumferential end of the shroud 5 integrally formed with the blades 1 and 2, and this is attached to another shroud 5 adjacent thereto.
Is joined to a small semicircular groove 7 provided at the opposite end of the groove.

In this structure, when one shroud 5 is viewed, a small semicircular protrusion 6 is provided at one end in the circumferential direction, and a small semicircular groove 7 is provided at the other end. The protrusions 6 on the same shroud 5
Means that the groove of the other adjacent shroud is joined to the projection of the other adjacent shroud on the opposite side.

These joints are formed by forming the radius of the groove 7 to be slightly larger than the radius of the protrusion 6 as shown in a plan projection in FIG. A line contact is made on a certain line on the peripheral surface to form a ring blade structure over the entire periphery.

By making the semicircular projection 6 and the groove 6 in line contact with each other, even if the contact reaction force between the adjacent shrouds 5 becomes large due to a change in the operating conditions, the rotational displacement of the shroud 5 about the radial axis can be achieved. Is hardly bound.

Therefore, as shown in FIG. 3, in the case of line contact, even if the contact reaction force between the shrouds 5 changes due to a change in the operating conditions, the constraint condition of the shroud 5 changes substantially while maintaining a substantially constant state. As a result, the frequency hardly changes.

Further, the vibration frequency of the entire circumference ring blade characteristic (band-shaped display D) in the line contact state is the single blade vibration characteristic (dashed line C).
, The gap is generated between the shrouds 5 during operation, and the frequency hardly changes from the state of the line contact even when the blade becomes a single blade.

Therefore, according to the present embodiment, unlike the shroud blade of the conventional structure described above, the vibration frequency does not greatly change depending on the operating conditions.
Resonance with the number of stationary blades and the number of stays can be reliably avoided.

Although the present invention has been described with reference to the illustrated embodiment, the present invention is not limited to such an embodiment.
It goes without saying that various changes may be made to the specific structure within the scope of the present invention.

[0018]

As described above, according to the present invention, a semicircular projection is provided at one end in the circumferential direction of the shroud, and a semicircular groove which is in line contact with the projection of the adjacent shroud is provided at the other end. The shroud-integrated steam turbine blades are provided to form a shroud-integrated steam turbine blade. The force does not change, and the frequency hardly changes even if the gap expands to a single wing state.

Therefore, the resonance with the number of stationary blades and the number of stays can be reliably avoided by adjusting the blade frequency at the design stage, so that the reliability can be greatly improved.

[Brief description of the drawings]

FIG. 1 is an assembly diagram of a shroud blade according to an embodiment of the present invention.

FIG. 2 is an explanatory view showing a line contact state between adjacent shrouds.

FIG. 3 is a Campbell diagram of a shroud wing in the embodiment of FIG. 1;

FIG. 4 is an assembly view of a conventional shroud blade.

FIG. 5 is a Campbell diagram of a conventional shroud wing.

[Explanation of symbols]

 1, Wing 3 Platform 4 T root blade root 5 Shroud 6 Projection 7 Groove

Claims (1)

[Claims] 1. A shroud-integrated steam turbine blade having a semicircular projection at one end in the circumferential direction of the shroud and a semicircular groove at the other end in line contact with the projection of the adjacent shroud. A shroud-integrated steam turbine blade, characterized in that: