JP2002004802A - Shroud of rotor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the shroud of a rotor so constituted that with the increase in the rotation speed of the rotor, contact of the end faces of the shroud with each other is rendered more firmly to increase rigidity, and thereby a natural frequency is increased to reduce resonance points in a range of the number of revolutions. SOLUTION: One shroud 1 of adjoining shrouds 1 is provided with a first end face 3a and a second end face 3b bent from the first end face 3a. Furthermore, the other shroud 1 is provided with a first end face 4a opposite to the first end face 3a and a second end face opposite to the second end face 3b. A gap G1 between the first end faces 3a and 4a is set to a value which is sufficient to allow contact of the end faces with each other at a low-speed rotation, and a gap G2 between the second end faces 3b and 4b is set to a value enough to allow contact of the end faces with each other at high-speed rotation.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shroud for a rotor such as a turbine.

[0002]

2. Description of the Related Art A shroud is protruded from an outer peripheral portion of a rotor such as a turbine in order to secure rigidity and improve a damping characteristic. When the rotation is stopped, the end faces of the adjacent shrouds are separated from each other with a small gap. However, at the time of high speed rotation, the gap disappears due to the torsional deformation of the rotating blade, and the end faces of the adjacent shrouds come into contact with each other.
In this way, by bringing all shrouds into contact on one circumference by torsional deformation of the rotor blade and integrally coupling,
The rigidity of the rotor is ensured and the damping characteristics are improved.

[0003]

This kind of rotor has a natural frequency and generates resonance at several resonance points determined by a Campbell diagram. Due to adverse effects such as generation of excessive load and stress on the rotor blades when resonance occurs, it is desirable to design such a rotor such that the resonance point is reduced as much as possible in the operating rotational speed range.

In order to reduce the resonance point in the operating speed range, it is necessary to make the end faces of the shroud firmly in contact with each other to increase the overall rigidity. Further, in this case, it is desirable that the higher the rotation speed, the higher the rigidity.

[0005] Accordingly, the present invention provides a method of operating the resonance point by rotating the resonance point by gradually increasing the contact between the end faces of the shroud and increasing the rigidity as the rotational speed of the rotor blades increases. It is an object to provide a rotor shroud that can be reduced in several ranges.

[0006]

According to a first aspect of the present invention, there is provided a shroud projecting from an outer peripheral portion of a rotary blade.
The opposing end faces of adjacent shrouds are shaped so that the contact area increases as the rotation speed increases.

Preferably, one of the adjacent shrouds has a first end surface and a second end surface bent from the first end surface. The other shroud has a first end face facing the first end face and a second end face facing the second end face, and has a shape in which a gap between the first end faces contacts at a low speed, Further, the gap between the second end faces is formed to be in contact with the high-speed rotation.

In the above configuration, when the rotation of the rotor is stopped, the end faces of the adjacent shrouds are separated from each other with a small gap therebetween. The contact area further increases as the contact occurs and the rotation speed increases. As the rotation speed increases, the contact area gradually increases, and the overall rigidity also increases.

According to a third aspect of the present invention, in the shroud protruding from the outer peripheral portion of the rotary blade, an elasticity imparting portion is formed at a tip end portion of the shroud which comes into contact with each other when rotating.

In the above configuration, when the rotation speed of the rotor increases, the tips of adjacent shrouds contact each other due to torsional deformation of the rotor, and when the rotation speed decreases, the tips of the shrouds separate from each other. Since the elasticity imparting portion is formed at the tip of the shroud, the tip of the shroud is easily deformed as the rotation speed changes, so that the end faces of the shroud come into firm contact with each other. According to a fourth aspect of the present invention, in the shroud protruding from the outer peripheral portion of the rotary blade, a slit portion is formed at a tip end portion of the shroud that comes into contact with each other during rotation. In the above configuration, when the rotation speed of the rotor increases, the tips of adjacent shrouds contact each other due to the torsional deformation of the rotor, and when the rotation speed decreases, the tips of the shrouds separate from each other. Since a slit is formed at the tip, the tip of the shroud comes into firm contact at the time of rated rotation, and the vibration of the rotor blade is attenuated by contact friction.

[0011]

(Embodiment 1) FIG. 1 is a front view of a shroud according to Embodiment 1 of the present invention, and FIG. 2 is an enlarged front view of a contact portion of the shroud.

In FIG. 1, a shroud 1 having a substantially elongated piece shape in front is projected from an outer peripheral portion of a moving blade 2 which is a rotating blade. The shroud 1 has a first protrusion 3 and a second protrusion 4 projecting from both sides of the outer periphery of a linear or substantially linear moving blade 2. When the rotor blade 2 rotates, the shroud 1
Is applied with a torsional force in the direction of arrow A, and is twisted in the same direction.

In FIG. 1 and FIG. 2A, a first projection 3 has a first end face 3a substantially perpendicular to the longitudinal direction of the rotor blade 2.
A second end surface 3b gently bent from the first end surface 3a to the adjacent shroud 1 side, a third end surface 3c bent sharply from the second end surface 3b, and a shroud from the third end surface 3c. 4th end surface 3d gently bent to one end
have.

The second protrusion 4 has a first end face 4a opposed to the first end face 3a, a second end face 4b gently bent from the first end face 3a and opposed to the second end face 3b, It has a third end face 4c extending from the first end face 4a to the other end of the rotor blade 2.

The shroud 1 of the rotor has the above-described structure, and will be described with reference to FIG. FIG. 2A shows a rotation stopped state. In this state, the first end face 3a and the first end face 4a face each other with a small gap G1. Further, the second end face 3b and the second end face 4b
They face each other with a gap G2 larger than one.

FIG. 2B shows a state of medium speed rotation.
In this state, the first end face 3
a and the first end surface 4a are in contact with each other. Also, the second end face 3
The gap between b and the second end face 4b decreases from G2 to G2 '. FIG. 2C shows a high-speed rotation state. In this state, the torsional deformation of the rotor blade 2 is further increased, so that the first end face 3a and the first end face 4a are in stronger contact with each other, and the second end face 3b is in contact with the second end face 4b.

As described above, the rotation speed is changed from the medium speed rotation to the high speed rotation, and the torsional deformation of the moving blade 2 is increased accordingly. As a result, the gap G1 and the gap G2 are gradually narrowed and the first protrusion 3 The contact area between the end surface of the second protrusion 4 and the end surface of the second protrusion 4 gradually increases. As the contact area increases, the first projection 3 and the second projection 4 are firmly coupled and coupled to each other, increasing the rigidity, increasing the natural frequency, and increasing the damping characteristics. Be improved.

The shape of the shroud is not limited to the above-described embodiment, but the point is that the contact area increases as the rotation speed increases, so that the rigidity can be more sufficiently secured. is there.

(Embodiment 2) FIG. 3 is a front view of a shroud according to Embodiment 2 of the present invention, and FIG. 4 is an enlarged front view of a contact portion of the shroud.

In FIG. 3, a shroud 11 having a substantially elongated piece shape in front is protruded from an outer peripheral portion of a moving blade 12 which is a rotating blade. The shroud 11 has symmetrically shaped protrusions 13 on both sides of the tip of a linear or substantially linear blade 12.
It is made up of protruding. The tip 13a of the projection 13 is a free end, and a slit-shaped split groove 14 is formed in the center of the tip 13a. Due to the split groove 14, the elasticity of the distal end portion 13a is ensured, the rigidity is reduced, and the distal end portion 13a is easily deformed. In addition, by making the distal end portion 13a a free end portion, a slight resilience is imparted. In addition, the shrouds 1 and 11 of the first and second embodiments are generally formed of metal such as steel.

In the above configuration, when the rotation of the rotor is stopped, the tip portions 13a of the adjacent shrouds 11 are separated from each other with a small gap G as shown in FIG. Due to the torsional deformation of the rotor blade 12, the tip 13
4a strongly contact each other as shown in FIG.

In this manner, the tip portions 13a of the shroud 11 repeatedly contact and separate from each other, but since the tip portions 13a are provided with elasticity by the split grooves 14, the tip portions 13a are changed in accordance with the change in the rotation speed. Is easily deformed. Therefore, as the rotational speed increases, the tip portions 13a are sufficiently deformed, and the tip portions 13a are elastically and closely joined to each other to come into contact with each other, thereby maintaining a strong integrated state and sufficient rigidity.

(Embodiment 3) FIG. 5 is an enlarged front view of a contact portion of a shroud according to Embodiment 3 of the present invention.

In the third embodiment, the protrusion 13 is used as the elasticity imparting portion.
The small hole 15 is formed in the front end portion 13a. Other configurations are the same as those of the second embodiment. Therefore, the third embodiment has the same operation and effect as the second embodiment. Further, the elasticity imparting portions such as the split grooves and the small holes shown in the second and third embodiments may be formed at the distal end portions of the first projection 3 and the second projection 4 of the first embodiment. In this way, the contact property and the coupling / coupling property between the first projection 3 and the second projection 4 are further improved.

(Fourth Embodiment) FIG. 6 is an enlarged front view of a contact portion of a shroud according to a fourth embodiment of the present invention. In the fourth embodiment, a slit 16 having a groove width of several tens μm to about 100 μ is formed as a slit at the tip 13 a of the projection 13. Other configurations are the same as the third embodiment.
Therefore, the fourth embodiment has the same operation and effect as the third embodiment. In addition, the slit 16 shown in the fourth embodiment may be formed at the tip of the first projection 3 or the second projection 4 of the first embodiment. The contact property and coupling / coupling property between the projection 3 and the second projection 4 are further improved.

As described above, according to the first and second aspects of the present invention, the contact area increases as the rotational speed increases, so that the rigidity can be more sufficiently secured and the damping characteristics can be improved.

According to the third and fourth aspects of the present invention,
Since the tip of the shroud is easily deformed in accordance with the rotation speed, the tips can be firmly integrated to ensure sufficient rigidity.

[Brief description of the drawings]

FIG. 1 is a front view of a shroud according to a first embodiment of the present invention.

FIG. 2 is an enlarged front view of a contact portion of a shroud according to the first embodiment of the present invention.

FIG. 3 is a front view of a shroud according to a second embodiment of the present invention.

FIG. 4 is an enlarged front view of a contact portion of a shroud according to a second embodiment of the present invention.

FIG. 5 is an enlarged front view of a contact portion of a shroud according to a third embodiment of the present invention.

FIG. 6 is an enlarged front view of a contact portion of a shroud according to a fourth embodiment of the present invention.

[Explanation of symbols]

 1, 11 Shroud 2, 12 Rotor blade (rotor blade) 3 First projection 3a, 4a First end face 3b, 4b Second end face 4 Second projection 13 Projection 14 Split groove (elasticity imparting part) 15 Small hole (elasticity imparting part) 16 Slit

Claims (4)

[Claims] 1. A shroud protruding from an outer peripheral portion of a rotating blade, wherein opposing end surfaces of adjacent shrouds are shaped such that a contact area increases as a rotation speed increases. Shroud. 2. One of the adjacent shrouds has a first end face and a second end face bent from the first end face, and the other shroud faces the first end face. A first end face and a second end face opposing the second end face, wherein the gap between the first end faces is in contact with the low-speed rotation, and the gap between the second end faces is high-speed. 2. A shroud for a rotary wing according to claim 1, wherein said shroud has a shape contacting by rotation. 3. A shroud for a rotary blade, wherein a shroud protruding from an outer peripheral portion of the rotary blade has an elasticity imparting portion formed at a tip end portion of the shroud which comes into contact with each other when rotating. 4. A shroud for a rotating blade, wherein a slit portion is formed at a tip portion of the shroud that comes into contact with each other when rotating, the shroud protruding from an outer peripheral portion of the rotating blade.