A turbine ( 1 ) of the present invention comprises that at one part of a tip part ( 51 ) of the blade ( 50 ) and an area ( 11 a) of the structure ( 11 ) corresponding to the tip part ( 51 ) of the blade, a stepped part ( 52 ) is formed, a seal fin ( 15 ) is provided at the another part of the tip part ( 51 ) of the blade and the area ( 11 a) of the structure ( 11 ), a cavity (C) is formed between the tip part ( 51 ) of the blade and the area ( 11 a) of the structure ( 11 ) and between the seal fin ( 15 ) and a partition wall ( 54, 15 ). The seal fin ( 15 ) comprises a fin main body part ( 16 ), and a space restriction part ( 17 ). Thus, the present invention provides a high performance turbine in which the leakage flow rate is reduced.
1. A turbine comprising:
a blade; and
a structure spaced apart from a tip side of the blade by a space and relatively rotated around a rotation axis of a shaft body with respect to the blade,
wherein a stepped part having a flat surface and a step surface protruding toward the structure is formed at a tip part of the blade, and the flat surface and the step surface are formed alternately from an upstream side toward a downstream side of the structure in a direction of the rotation axis,
a seal fin is provided to the structure at a position facing an upstream part of the flat surface, and extends toward the stepped part, and
a first cavity is formed between the tip part of the blade and the structure, and formed between the seal fin and a partition wall facing toward the seal fin at the upstream side, and
wherein the seal fin comprises:
a space restriction part that extends from the structure and has an inner circumference wall surface facing the flat surface,
a side surface facing toward the upstream side, and
a fin main body part that extends toward the tip part of the blade from a downstream portion of the inner circumference wall surface in the direction of the rotation axis and forms a small space between the flat surface,
wherein a second cavity smaller than the first cavity is formed by the flat surface, the space restriction part, and the fin main body part, in an upstream portion of the fin main body part in the direction of the rotation axis,
wherein the second cavity is formed at the downstream side of the first cavity,
wherein the fin main body part is provided so as to be in one-to-one correspondence with the flat surface, and
wherein a height from the flat surface to the structure is larger than a height from the flat surface to the inner circumference wall surface.
2. The turbine according to claim 1 , wherein
the inner circumference wall surface is recessed in an arc shape when seen from a cross-sectional view.
3. The turbine according to claim 1 , wherein
the inner circumference wall surface is connected to the fin main body part in an arc shape when seen from a cross-sectional view.
4. The turbine according to claim 1 , wherein
at least a tip side of the fin main body part extends at a tilted angle toward the upstream side in the direction of the rotation axis.
5. The turbine according to claim 1 , wherein
the side surface is spaced apart from the fin main body part by an interval on the upstream side in the direction of the rotation axis, and is a radial direction wall body extending toward the stepped part and forming a space larger than the small space between the wall body and the stepped part.
6. The turbine according to claim 1 , wherein
a size of the small space is H, and a distance between the fin main body part and an end edge of the upstream side in the direction of the rotation axis of the stepped part is L,
the following Equation (1) is satisfied:
0.7H≦L (1).
7. The turbine according to claim 1 , wherein
more than one stepped part is provided in such a way that protrusion heights of the stepped parts are gradually increased from the upstream side toward the downstream side in the direction of the rotation axis,
a plurality of the seal fins are provided, and one of the seal fins extending toward the stepped part is provided for each of the stepped parts at the structure, and
one of the seal fins corresponding to the stepped part is the partition wall facing another of the seal fins corresponding to the stepped part adjacent to the downstream side in the direction of the rotation axis.
8. The turbine according to claim 1 , wherein more than one stepped part is provided in such a way that protrusion heights of the stepped parts are gradually increased from the upstream side toward the downstream side in the direction of the rotation axis,
a part of the structure corresponding to the tip part of the blade is an annular recess, and
the partition wall, which faces the seal fin corresponding to the stepped part disposed at the farthest upstream side among the plurality of stepped parts in the direction of the rotation axis, is formed by an inner wall surface of the recess on the upstream side in the direction of the rotation axis.
9. The turbine according to claim 1 , wherein
a distance between a position at which the fin main body is formed and an end edge of the inner circumference wall surface of the space restriction part in the direction of the rotation axis is shorter than a distance between the position at which the fin main body is formed and an end edge of the flat surface in the direction of the rotation axis.
10. The turbine according to claim 1 , wherein
a size of the fin main body part in the direction of the rotation axis is smaller than that of the inner circumference wall surface in the direction of the rotation axis.
11. A turbine comprising:
a blade; and
a structure spaced apart from a tip side of the blade by a space and relatively rotated around a rotation axis of a shaft body with respect to the blade,
wherein a stepped part having a flat surface and a step surface protruding toward a tip part of the blade is formed at the structure, and the flat surface and a step surface are formed alternately from an upstream side toward a downstream side of the structure in a direction of the rotation axis,
a seal fin is provided to the tip part of the blade at a position facing an upstream part of the flat surface, and extends toward the stepped part, and
a first cavity is formed between the tip part of the blade and the structure and formed between the seal fin and a partition wall facing toward the seal fin at the upstream side, and
wherein the seal fin comprises:
a space restriction part that extends from the tip part of the blade and has an inner circumference wall surface facing the flat surface,
a side surface facing toward the upstream side, and
a fin main body part that extends toward the structure from a downstream portion of the inner circumference wall surface in the direction of the rotation axis and forms a small space between the flat surface,
wherein a second cavity smaller than the first cavity is formed by the flat surface, the space restriction part, and the fin main body part, in an upstream portion of the fin main body part in the direction of the rotation axis,
wherein the second cavity is formed at the downstream side of the first cavity,
wherein the fin main body part is provided so as to be in one-to-one correspondence with the flat surface, and
wherein a height from the flat surface to the tip part of the blade is larger than a height from the flat surface to the inner circumference wall surface.
12. The turbine according to claim 11 , wherein
the inner circumference wall surface is recessed in an arc shape when seen from a cross-sectional view.
13. The turbine according to claim 11 , wherein
the inner circumference wall surface is connected to the fin main body part in an arc shape when seen from a cross-sectional view.
14. The turbine according to claim 11 , wherein
at least a tip side of the fin main body part extends at a tilted angle toward the upstream side in the direction of the rotation axis.
15. The turbine according to claim 11 , wherein
the side surface is spaced apart from the fin main body part by an interval on the upstream side in the direction of the rotation axis, and is a radial direction wall body extending toward the stepped part and forming a space larger than the small space between the wall body and the stepped part.
16. The turbine according to claim 11 , wherein
a size of the small space is H, and a distance between the fin main body part and an end edge of the upstream side in the direction of the rotation axis of the stepped part is L,
the following Equation (1) is satisfied:
0.7H≦L (1).
17. The turbine according to claim 11 , wherein
more than one stepped part is provided in such a way that protrusion heights of the stepped parts are gradually increased from the upstream side toward the downstream side in the direction of the rotation axis,
a plurality of the seal fins are provided, and one of the seal fins extending toward the stepped part is provided for each of the stepped parts at the tip part of the blade, and
one of the seal fins corresponding to the stepped part is the partition wall facing another of the seal fins corresponding to the stepped part adjacent to the downstream side in the direction of the rotation axis.
18. The turbine according to claim 11 , wherein more than one stepped part is provided in such a way that protrusion heights of the stepped parts are gradually increased from the upstream side toward the downstream side in the direction of the rotation axis,
a part of the structure corresponding to the tip part of the blade is an annular recess, and
the partition wall, which faces the seal fin corresponding to the stepped part disposed at the farthest upstream side among the plurality of stepped parts in the direction of the rotation axis, is formed by an inner wall surface of the recess on the upstream side in the direction of the rotation axis.
19. The turbine according to claim 11 , wherein
a distance between a position at which the fin main body is formed and an end edge of the inner circumference wall surface of the space restriction part in the direction of the rotation axis is shorter than a distance between the position at which the fin main body is formed and an end edge of the flat surface in the direction of the rotation axis.
20. The turbine according to claim 11 , wherein
a size of the fin main body part in the direction of the rotation axis is smaller than that of the inner circumference wall surface in the direction of the rotation axis.