Cooling system for a main body used in a gas stream

Details Cooling system for a main body used in a gas stream Cooling system for a main body used in a gas stream

1999-10-20

2001-01-23

Verdier, Christopher (Department: 3745)

Rotary kinetic fluid motors or pumps

With passage in blade, vane, shaft or rotary distributor...

C415S914000, C416S09700R, C137S806000, C137S809000, C137S811000, C137S827000, C165S109100, C165S134100, C165S908000

Reexamination Certificate

active

06176676

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to a structure with elements including a main body used in a gas stream, and especially relates to the main body including a plurality of fluid passages used in the gas stream.
BACKGROUND OF THE INVENTION
In a gas turbine, if the gas temperature is high during a first stage of the turbine, the efficiency for generating electric power increases. However, in order to raise the gas temperature for the first stage of the turbine, the heat-durability of the turbine blade and turbine nozzle should also be increased. As a method for raising the heat-durability of the gas turbine, film cooling by fluid on the blade surface is well known.
FIG. 1
is a schematic diagram of the turbine blade of the gas turbine according to the prior art. The turbine blade consists of a main body
1
of the blade and a base
2
to attach the main body to a rotor (not shown in FIG.
1
).
FIG. 2
is a sectional plan of line K—K of FIG.
1
.
FIG. 3
is a sectional plan of the J—J line of FIG.
1
. As shown in FIG.
2
and
FIG. 3
, three coolant passages
3
a
,
3
b
,
3
c
are formed in the base
2
and the main body
1
. The three coolant passages are connected to a supply source of cooling fluid. The cooling fluid in the coolant passage
3
a
,
3
b
,
3
c
executes convective cooling through the base
2
and the main body
1
. When the cooling fluid flows through the coolant passages
3
a
,
3
b
, it flows out through a plurality of outlets
8
on the leading edge
4
, side wall
5
, other side wall
6
, tip
7
. The cooling fluid in the coolant passage
3
c
flows out through outlets
10
on the trailing edge
9
.
The outlet of coolant passage is normally formed as an ellipse.
FIG. 4
is a schematic diagram of the outlet of the coolant passage on the blade surface according to the prior art.
FIG. 5
is a sectional plan of line L—L of FIG.
4
. As shown in FIG.
4
and
FIG. 5
, in the outlet
8
passing through the side wall
5
and the other side wall
6
, the center line
12
of the outlet of the coolant passage is inclined in the direction of the gas stream
11
on the surface of the wall
5
(
6
). The cooling fluid flowing from the outlet
8
is mixed with the gas stream
11
flowing over the surface at high speed, and cools the surface by forming a film-like layer over it. As a method for setting the outlet on the surface, plural lines of the outlets
8
perpendicular to the direction of the gas stream
11
may be set as shown in FIG.
6
and FIG.
7
. In order to supplement the outlets
8
on the upstream side, the outlets
8
on the downstream side, whose position is different from the position of the outlets on the upstream side, are set as shown in FIG.
8
. Furthermore, in order to strengthen the film cooling effectiveness of the spread of the fluid, the diameter of the outlet
13
is gradually increased as it reaches the surface as shown in FIG.
9
A and FIG.
9
B. Alternatively, as shown in
FIG. 10
, the outlet
13
is opened at fixed intervals as it reaches the surface, thus resembling a staircase.
However, in the film cooling method in which the center line
12
of the coolant passage is inclined in the direction of the stream, the following problem occurs.
The cooling fluid flowing from the outlet
8
has a high Kinetic energy stream that crosses the direction of the gas stream flowing along the surface. Therefore, as shown in
FIG. 11
, a separation of the coolant as the cooling fluid flows up in a columnar shape occurs. As a result, the gas stream
11
is divided by a pillar
14
of cooling fluid flown from the outlet
8
and rolled up in the downstream area of the pillar
14
. This makes it is difficult for the fluid film to cover the surface
5
(
6
) and therefore film cooling effectiveness reduces. Furthermore, when the outlet is shaped as shown in FIG.
9
B and
FIG. 10
, the fluid film covers only 70% of the surface interval between neighboring outlets. In addition, the pressure of the fluid flowing from the outlet is low because of the wide outlet
13
. Therefore, in the downstream area of the outlet
8
on the surface
5
(
6
), the gas stream
11
mixes with the cooling fluid
14
, and the film cooling effectiveness is low.
On the other hand, according to the prior method shown in
FIGS. 12A and 12B
, the direction of the coolant passage is inclined in a direction different from the direction of the gas stream along the surface (i.e., the “lateral direction”). In this method, the fluid diffuses laterally in the direction of the gas stream. In short, the flown fluid diffuses only along the lateral area in the direction of the gas stream. The film cooling effectiveness of the fluid for downstream area is therefore low.
As another prior method shown in
FIGS. 13A and 13B
, the outlet is shaped as a diffusion type in addition to the specific feature of
FIGS. 12A and 12B
. In this method, the center line of the diffusion part is inclined in the lateral direction similar to the center line of the outlet of the coolant passage. Therefore, the film cooling effectiveness of the fluid over the downstream area is low in the same way as shown in
FIGS. 12A and 12B
.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a structure with elements that are able to suppress the roll up of the gas stream for the fluid down stream of each outlet on surface of the main body.
It is another object of the present invention to provide a structure with elements, which are able to uniformly spread the cooling fluid over a wide area of the surface as a fluid film.
According to the present invention, there is provided a structure with elements including a main body of the elements used in the gas stream and a plurality of fluid passages. Each outlet opens onto the surface of the main body and fluid flows from each outlet through the passage to cover the surface as a fluid film, wherein the plurality of fluid passages, comprising: a first fluid passage, from which fluid flows in the direction of the gas stream on the surface, and a second fluid passage, adjoining the first fluid passage from which fluid flows against the gas stream to suppress the roll up of the gas stream caused by the fluid downstream of each outlet.
Further in accordance with the present invention, there is provided a structure with elements, including a main body of the element used in the gas stream and a plurality of fluid passages. The fluid passages have outlets which opens onto the surface of the main body through which the fluid flows, covering the surface in the form of a film. The plurality of fluid passages, comprise: a first fluid passage, from which fluid flows along a predetermined direction different from the direction of the gas stream on the surface, and a second fluid passage adjoining the first fluid passages, from which fluid flows against the gas stream to suppress roll up of the gas stream caused by the fluid downstream of each outlet.
Further in accordance with the present invention, there is provided a structure with elements, including a main body of the element used the gas stream and a plurality of fluid passages, each outlet of which opens onto the surface of the main body. Fluid flows from each outlet through the passage to cover the surface as a fluid film. The plurality of fluid passages are configured so that a center line of each fluid passage is inclined in the direction of the gas stream flowing on the surface.
Further in accordance with the present invention, there is provided structure with elements, including a main body of the element used in the gas stream and a plurality of fluid passages, each outlet of which opens onto the surface of the main body. Fluid flows from each outlet through the passage to cover the surface as a fluid film. The plurality of fluid passages are configured so that a center line of each fluid passage is inclined in the direction of the gas stream on the surface. The fluid passages include an inner wall forming the fluid passage toward the outlet on the surface of the main body. The inner w

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