Seal for a joint or juncture – Seal between relatively movable parts – Close proximity seal
Reexamination Certificate
1998-02-24
2001-02-20
Knight, Anthony (Department: 3626)
Seal for a joint or juncture
Seal between relatively movable parts
Close proximity seal
Reexamination Certificate
active
06189891
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a gas turbine seal apparatus for preventing cooling air from leaking into a high temperature combustion gas passage between an end portion of a moving blade platform and a stationary blade inside shroud.
2. Description of the Related Art
FIG. 4
is a cross sectional view which shows a seal apparatus for preventing cooling air from leaking between a moving blade and a stationary blade of a conventional gas turbine. In the drawing, reference numeral
1
denotes a moving blade, reference numeral
2
denotes a platform thereof, and reference numeral
3
denotes a seal pin inserted between the adjacent platforms in a circumferential direction and constituted by a seal pin
3
a
extending in an axial direction and a seal pins
3
b
provided on both sides in an inclined manner. Reference numeral
4
denotes a shank portion disposed below the platform
2
, reference numeral
5
denotes a disc, and reference numerals
6
and
7
denote seal plates for sealing opposite sides of the shank portion
4
.
Reference numeral
11
denotes a stationary blade, reference numeral
12
denotes an inside shroud, and reference numeral
13
denotes an outside shroud. Reference numeral
14
denotes a cavity disposed below the inside shroud
12
, reference numeral
15
denotes a seal box, and reference numerals
16
and
17
denote honeycomb seals mounted on front and rear end portions
12
a
,
12
b
of the inside shroud
12
. The honeycomb seals
16
,
17
are structured such that a plurality of honeycomb cores are disposed in such a manner as to be open downward. Reference numerals
18
and
19
each denote a space formed by the seal plates
6
and
7
of the moving blade
1
and the adjacent stationary blade
11
, and these spaces are areas where high air pressure is formed.
In the structure of the moving blade and the stationary blade mentioned above, cooling air is introduced to the moving blade
1
from the disc
5
through a passage (not shown) by suppling the cooling air from the shank portion
4
to a cooling passage for the moving blade
1
. However, the cooling air leaks from a contact portion between the seal pins
3
a
and
3
b
or a gap between the platforms adjacent to the end portions
2
a
and
2
b
of the platform
2
, and the air directly flows out to the spaces
18
and
19
or the combustion gas passage. Further, since air for the stationary blade
11
leaks from the cavity
14
through the seal box
15
, the spaces
18
and
19
are under high pressure. The end portions
2
a
and
2
b
of the platform
2
in the moving blade
1
and the honeycomb seals
17
and
16
provided on the inside shroud
12
of the stationary blade
11
are opposed to each other so as to form the seal mechanisms. The seal mechanisms are intended to prevent more than the necessary amount of cooling air from leaking into the high temperature combustion gas passage and being wasted.
As mentioned above, the seal between the moving blade platform and the stationary blade inside shroud end portion in the conventional gas turbine is constructed as shown in
FIG. 4
such that the seals are formed between the honeycomb seals
16
and
17
provided on both ends
12
a
and
12
b
of the inside shroud
17
in the stationary blade
11
and the end portions
2
b
and
2
a
of the moving blade platform
2
. Thereby sealing the air which is going to escape into the high temperature combustion gas passage. However, in this seal mechanism, the end portions
2
a
and
2
b
of the platform
2
have a simple shape in comparison with the honeycomb seals
17
and
18
, and thus the sealing performance is not always good, so that the seal is insufficient. Accordingly, more than the necessary amount of the sealing air tends to leak into the high temperature combustion gas passage, so that the amount of cooling air is increased, thereby inviting deterioration in the performance of the gas turbine.
In the seal mechanisms, as the flow passage becomes complex and the resistance is increased, the leakage of air is reduced and the sealing performance is improved. However, in the honeycomb seals
16
and
17
, the air goes in and out through an inner portion of a multiplicity of honeycomb cores, and the flow becomes complex and the resistance to the flow is increased so as to provide a sealing effect. In contrast, the end portions
2
a
and
2
b
of the platform
2
have a simple shape so that the effect of the flow resistance is not adequately obtained. Accordingly, there is room for improving the current seal mechanism.
SUMMARY OF THE INVENTION
Accordingly, a first object of the present invention is to provide a gas turbine seal apparatus structured such that a shape of a moving blade side seal mechanism is constructed so as to increase flow resistance and enhance the sealing performance in order to improve the sealing performance between a moving blade platform and a stationary blade inside shroud, thereby reducing the amount of cooling air leaking into the high temperature combustion gas and preventing the performance of the gas turbine from deteriorating.
Further, a second object of the invention is to make the seal apparatus in a form which can be integrally manufactured so as to be easily processed and mounted, in the seal apparatus having an improved sealing performance mentioned above.
The invention provides the following (1) and (2) means, respectively, for achieving the first and second objects mentioned above.
(1) A gas turbine seal apparatus in which a seal plate is provided in an inner portion of a moving blade platform of a moving blade, which is disposed in a periphery of a rotating shaft. A platform end portion, to which an upper portion of the seal plate is connected, and a honeycomb seal, provided on an inside shroud end of a stationary blade disposed adjacent to the moving blade, are opposed to each other. Also, a space formed by the seal plate of the moving blade and the adjacent stationary blade is sealed from a combustion gas passage. Furthermore, a plurality of seal fins are provided on an upper portion of the seal plate and are arranged in such a manner so as to oppose a honeycomb seal surface. The seal fins are each inclined in such a manner so as to oppose the flow of air flowing out toward the combustion gas passage. Also, an inclined angle of each of the seal fins is set to 0<&thgr;≦90° where an angle with respect to the honeycomb seal surface is &thgr;.
(2) A gas turbine seal apparatus, as recited in item (1) above, in which the seal plate and the seal fins are integrally formed.
In the structure of the present invention, a plurality of seal fins, opposing the honeycomb seal provided on the inside shroud of the stationary blade, are provided on the upper portion of the seal plate disposed in the inner portion of the platform of the moving blade. Since these seal fins are inclined in a direction against the outflow of air, the air flow is brought into contact with the plurality of seal fins in addition to the flow resistance in the inflow and outflow within the core of the honeycomb seal, so that the flow is disturbed and the resistance is provided, thereby increasing the flow resistance. Accordingly, in comparison with the simple seal structure at the extension portion of the conventional moving blade end portion, the air cannot easily flow out. Since a plurality of seal fins are disposed along the honeycomb seal surface, and further are inclined in such a manner so as to oppose the air flow direction, the seal fins are oriented not in the direction of the air flow but in the opposing direction, so that the air flow resistance is further increased and the sealing effect is increased by making it hard to flow in comparison with the conventional structure.
In the structure, described above in item (2), since the seal plate and the seal fins are integrally processed, it is easy to manufacture them, it is simple to mount them, and further, the complex projecting portion is reduced in the platform to which the seal plate
Fukuno Hiroki
Hashimoto Yukihiro
Hirokawa Kazuharu
Ito Eisaku
Suenaga Kiyoshi
Beres John L.
Knight Anthony
Mitsubishi Heavy Industries Ltd.
Wenderoth , Lind & Ponack, L.L.P.
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