Fluid reaction surfaces (i.e. – impellers) – With heating – cooling or thermal insulation means – Changing state mass within or fluid flow through working...
Reexamination Certificate
2001-02-23
2002-11-19
Look, Edward K. (Department: 3745)
Fluid reaction surfaces (i.e., impellers)
With heating, cooling or thermal insulation means
Changing state mass within or fluid flow through working...
C415S115000
Reexamination Certificate
active
06481967
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to a gas turbine moving blade and more particularly to a gas turbine moving blade which is improved with regard to its blade and platform cooling structure so as to prevent occurrence of cracks due to thermal stresses caused by temperature changes during gas turbine starts and stops, or caused by high temperature combustion gas.
2. Description of the Prior Art
In
FIG. 14
, which is a cross sectional view of a representative first stage moving blade of a prior art gas turbine, numeral
20
designates the moving blade, numeral
21
designates a blade root portion and numeral
22
designates a platform. In the blade root portion
21
, there are provided cooling passages
23
,
24
,
25
,
26
, which are independent of each other. The cooling passage
23
is a passage on a blade leading edge side to communicate with a cooling passage
23
a
provided in a blade leading edge portion. Cooling air represented by arrow
40
flows into the cooling passage
23
from a turbine rotor side to flow through the cooling passage
23
a
and to flow out of a blade tip portion for cooling the blade leading edge portion and, at the same time, to flow out of cooling holes
29
for effecting a shower head film cooling of the blade leading edge portion. Cooling air represented by arrow
41
flows into the cooling passage
24
to flow through a cooling passage
24
a
provided in the blade, and then turns at the blade tip portion to flow through a cooling passage
24
b
, and turns again at a blade base portion to flow through a cooling passage
24
c
, and then flow out of the blade tip portion. In this process of the flow, the cooling air represented by arrow
41
cools a blade interior and, at the same time, flows out of cooling holes, to be described later with respect to
FIG. 15
, onto a blade surface for effecting a film cooling thereof.
Cooling air represented by arrow
42
entering the cooling passage
25
, and cooling air represented by arrow
43
entering the cooling passage
26
, join together to flow through a cooling passage
25
a
, then turn at the blade tip portion to flow through a cooling passage
25
b
, and turn again at the blade base portion to flow through a cooling passage
25
c
. In this process of the flow, the cooling air represented by arrows
42
,
43
cools the blade interior and, at the same time, flows out of cooling holes, to be described later with respect to
FIG. 15
, onto the blade surface for effecting the film cooling thereof. A remaining portion of the cooling air represented by arrows
42
,
43
flows out of cooling holes
28
of a blade trailing edge
27
for effecting a pin fin cooling of a blade trailing edge portion.
In
FIG. 15
, which is a cross sectional view taken on line B—B of
FIG. 14
, a portion of the cooling air flowing through the cooling passage
23
a
in the blade leading edge portion flows out of the blade through the cooling holes
29
for effecting the shower head film cooling of the blade leading edge portion. Also, a portion of the cooling air flowing through the cooling passage
24
c
flows outside obliquely through cooling holes
30
for effecting the film cooling of the blade surface. Likewise, a portion of the cooling air flowing through the cooling passage
25
c
flows outside obliquely through cooling holes
31
for effecting the film cooling of the blade trailing edge portion. It is to be noted that although the cooling holes
29
,
30
,
31
only are illustrated, there are actually provided a multiplicity of cooling holes other than the mentioned three kinds of the cooling holes
29
,
30
,
31
.
In FIGS.
16
(
a
) and
16
(
b
), which are explanatory plan views of a cooling structure of the platform
22
, FIG.
16
(
a
) shows an example to cool a front portion, or a blade leading edge side portion, of the platform
22
as well as to cool both side portions, or blade ventral and dorsal side portions, of the platform
22
. And FIG.
16
(
b
) shows another example to cool upper surface portions of both of the side portions of the platform
22
in addition to the cooled portions of FIG.
16
(
a
). In FIG.
16
(
a
), there are bored cooling passages
50
a
,
50
b
in the front portion and both of the side end portions of the platform
22
so as to communicate with the cooling passage
23
of the leading edge portion of the moving blade
20
. Cooling air represented by arrows
72
a
,
72
b
flows through the cooling passages
50
b
,
50
a
, respectively, for cooling the front portion and both of the side portions of the platform
22
, and flows out through a rear portion, or a blade trailing edge side portion, of the platform
22
as air represented by arrows
72
c
,
72
d.
In FIG.
16
(
b
), in addition to the cooling passages
50
a
,
50
b
of FIG.
16
(
a
), there are provided a plurality of cooling holes
51
a
,
51
b
, respectively, in both of the side portions of the platform
22
so as to open at an upper surface of the platform
22
. These cooling holes
51
a
,
51
b
communicate with one or more of the cooling passages leading to the interior of the moving blade
20
, so that cooling air flows through the cooling holes
51
a
,
51
b
to flow out onto the upper surface of the platform
22
and cool both of the side portions of the platform
22
. Thus, in the gas turbine moving blade, the moving blade
20
as well as the platform
22
are cooled as described with respect to
FIGS. 14
to
16
(
b
), so that thermal influences resulting from high temperature combustion gas are mitigated.
In FIGS.
17
(
a
)-
17
(
c
), which show an example of a second stage moving blade in the prior art, FIG.
17
(
a
) is a cross sectional view thereof, FIG.
17
(
b
) is a cross sectional view taken on line F—F of FIG.
17
(
a
) and FIG.
17
(
c
) is a cross sectional view taken on line G—G of FIG.
17
(
a
). In FIGS.
17
(
a
) and (
b
), numeral
180
designates the second stage moving blade, numeral
181
designates a blade root portion and numeral
182
designates a platform. In the blade root portion
181
, there are provided cooling passages
183
,
184
,
185
, which are independent of each other. The cooling passage
183
is a passage on a blade leading edge side to communicate with a cooling passage
183
a
provided in a blade leading edge portion. Cooling air represented by arrow
190
flows into the cooling passage
183
from a turbine rotor side to flow through the cooling passage
183
a
for cooling the blade leading edge portion and to flow outside through a blade tip portion. Cooling air represented by arrow
191
flows into the cooling passage
184
to flow through a cooling passage
184
a
provided in the blade, then turns at the blade tip portion to flow through a cooling passage
184
b
, and turns again inwardly toward a blade base portion. In the blade base portion, the cooling air represented by arrow
191
, and cooling air represented by arrow
192
flowing through the cooling passage
185
, join together and flow into a cooling passage
184
c
. In the cooling passage
184
c
, the cooling air represented by arrows
191
,
192
flows between pin fms
195
for enhancing the cooling effect, and flows outside through slots
186
provided in a blade trailing edge as well as through a hole of the blade tip portion. In this process of the cooling air flow, the blade is cooled.
In FIG.
17
(
c
), there is provided a blade tip thinned portion
187
along each of blade tip edge portions of the moving blade
180
so as to function as a seal of air leaking toward blade rear stages from the blade tip. Numeral
188
designates a plug, which plugs up openings provided for working purposes when the moving blade
180
is being manufactured. In the second stage moving blade
180
as so constructed, the cooling air is led into the interior of the blade, so that thermal influences resulting from high temperature combustion gas are mitigated.
As mentioned above, in the gas turbine moving blade, the blade and the platform are cooled by flowing the cooling air,
Aoki Sunao
Arimura Hisato
Hashimoto Yukihiro
Ishiguro Tatsuo
Kubota Jun
Kershteyn Igor
Look Edward K.
Mitsubishi Heavy Industries Ltd.
Wenderoth , Lind & Ponack, L.L.P.
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