Sealing device and rotary machine

1. A sealing device for suppressing a leakage flow of a fluid via an annular gap between a stationary member and a rotary member of a rotary machine, the sealing device comprising:

a support fin having an annular shape; and

a movable fin having an annular shape and being disposed adjacent to the support fin in an axial direction,

wherein the movable fin comprises:

a fixing region disposed on a root-end side of the movable fin and fixed to the support fin; and

a tip region including a tip of the movable fin and configured to be movable with respect to the support fin,

wherein the movable fin has a thermal expansion coefficient that is greater than a thermal expansion coefficient of the support fin, and

wherein, when the rotary machine is stopped, the tip of the movable fin is not radially inward of the support fins, and when the rotary machine is operating and the temperature of the seal device is elevated, the tip of the movable fin moves radially inward of the support fin due to the greater thermal expansion coefficient of the movable fin.

2. The sealing device according to claim 1 , wherein the movable fin is attached to the support fin only in the fixing region on the root-end side of the movable fin.

3. The sealing device according to claim 1 , wherein the movable fin includes a plurality of segments arranged in a circumferential direction.

4. The sealing device according to claim 3 ,

wherein each of the segments forms part of the root-end side of the movable fin and the fixing region is a partial portion of a circumferential-directional range on the root-end side, and

wherein each of the segments of the movable fin is allowed to expand thermally in a radial direction and the circumferential direction starting from the fixing region.

5. The sealing device according to claim 4 , wherein the fixing region is positioned in a center, with respect to the circumferential direction, of the circumferential-directional range on the root-end side of each of the segments.

6. The sealing device according to claim 1 , wherein the sealing device is capable of use in a rotary machine which H m1 ≥H f1 and H m2 <H f2 are satisfied, provided that,

H m1 is a clearance formed between the stationary member or the rotary member and the movable fin when the rotary machine is stopped,

H f1 is a clearance formed between the stationary member or the rotary member and the support fin when the rotary machine is stopped,

H m2 is a clearance formed between the stationary member or the rotary member and the movable fin when the rotary machine is in rated operation, and

H f2 is a clearance formed between the stationary member or the rotary member and the support fin when the rotary machine is in rated operation.

7. The sealing device according to claim 1 , wherein the movable fin is disposed on a high-pressure side of the support fin.

8. The sealing device according to claim 7 , further comprising a seal ring configured to be engaged with a groove formed on the stationary member or the rotary member, the seal ring having, on a tip-end side, a plurality of the support fins arranged in the axial direction,

wherein the movable fin is disposed at least on the high-pressure side of the support fin positioned most upstream with respect to the leakage flow.

9. The sealing device according to claim 7 , wherein a gap is formed between a tip portion of the movable fin and a tip portion of the support fin.

10. The sealing device according to claim 1 , further comprising a seal ring configured to be engaged with a groove formed on one of the stationary member or the rotary member, the seal ring being connected to, on a tip-end side, the support fin,

wherein the movable fin extends obliquely with respect to a radial direction from a root portion of the movable fin positioned in an axial-directional range of the groove toward a tip portion of the movable fin positioned outside the axial-directional range of the groove.

11. The sealing device according to claim 1 , wherein the support fin and the movable fin are curved in a cross section, taken in the axial direction, of the rotary machine.

12. The sealing device according to claim 11 ,

wherein the sealing device satisfies a relational expression θ f1 >θ f2 , provided that,

θ f1 is an angle formed between a radial direction at the root-end side of the support fin and a tangent direction, in the cross section taken in the axial direction, of a surface of the support fin which is on a side adjacent to the movable fin, and

θ f2 is an angle formed between the tangent direction and the radial direction at a tip-end side of the support fin, and

wherein the movable fin is curved along the support fin.

13. A rotary machine comprising:

a stationary member;

a rotary member disposed so as to face the stationary member; and

the sealing device according to claim 1 disposed in an annular gap between the stationary member and the rotary member.