Fluid reaction surfaces (i.e. – impellers) – With heating – cooling or thermal insulation means – Changing state mass within or fluid flow through working...
Reexamination Certificate
1999-02-11
2001-03-06
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
06196798
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Technical Field of the Invention
The present invention relates to a cooled blade of a gas turbine, and in particular to a structure capable of preventing cracks in peripheral portions of air-transpiration holes provided at a leading edge portion of the blade for shower-head cooling thereof.
2. Description of the Related Art
Since the stationary blades and the moving blades of a gas turbine are exposed to a high temperature gas resulting from combustion, it is necessary to cool the interior of the blades. To this end, cooling air passages are provided inside of the blades and cooling air is forced to flow through the cooling air passages to cool the interiors of the blades.
FIG. 4
is a perspective view showing a conventional cooled blade of a gas turbine. Referring to the figure, a cooled blade
11
has a leading edge
12
and a trailing edge
13
. As can be seen, a number of air-transpiration holes
14
formed in the leading edge portion
12
of the cooled blade
11
blowout the cooling air from the cooling air passage formed inside of the blade to thereby effect so-called shower-head cooling.
FIG.
5
(
a
) is a sectional view taken along line C—C in
FIG. 4
, and FIG.
5
(
b
) is a sectional view taken along line D—D in FIG.
4
. In these figures, a plurality of air-transpiration holes
14
provided in the leading edge portion
12
of the cooled blade
11
for shower-head cooling are shown in detail. The cooling air flowing through a cooling air passage
15
formed inside of the blade is blown out to the blade surface by way of the air-transpiration holes
14
to shower-head cool the blade surface.
As is shown in FIG.
5
(
b
), each of the air-transpiration holes
14
is formed with an inclination relative to the blade surface at the leading edge portion
12
. The cooling air blown out of the air-transpiration holes
14
is forced to flow along the blade surface due to such inclination of the air-transpiration holes
14
, whereby effective cooling of the blade surface can be achieved.
However, as a result of the oblique disposition of the air-transpiration holes
14
relative to the leading edge
12
, acute-angled portions
30
are formed between the blade surface and the air-transpiration holes
14
at inlet/outlet ports thereof. In the blade structure having the acute-angled portions
30
mentioned above, thermal stress taking place around the air-transpiration holes
14
will tend to concentrate at the acute-angled portions
30
, creating a problem in that cracks are likely to occur around the air-transpiration holes
14
.
OBJECT OF THE INVENTION
In light of the state of the art described above, an object of the present invention, which has been made to solve the problem mentioned above, is to protect the leading edge portion of a cooled blade of a gas turbine against cracks by preventing the generation of high thermal stress around the air-transpiration holes by altering the angular disposition of the air-transpiration holes of the cooled blade of the gas turbine relative to the leading edge thereof such that acute-angled portions are eliminated.
SUMMARY OF THE INVENTION
The present invention proposes the following means to achieve the object described above.
A cooled blade of a gas turbine is provided having a cooling air passage formed inside of the cooled blade through which cooling air is caused to flow for cooling the interior of the blade and a number of air-transpiration holes formed at a leading edge portion thereof so that the above-mentioned leading edge portion of the cooled blade is shower-head cooled by the cooling air blowout from the cooling air passages by way of the air-transpiration holes, characterized in that the air-transpiration holes are disposed, relative to the blade surface at the leading edge portion, so as to reduce concentration of stress around inlet/outlet ports when thermal stress at the inlet/outlet ports of the air-transpiration holes at the leading edge portion of the cooled blade is generated. In particular, the air-transpiration holes are preferably provided substantially orthogonal to the blade surface at the leading edge portion.
In the cooled blade of a gas turbine according to the present invention, the air-transpiration holes are formed so as to substantially orthogonally intersect the blade surface at the leading edge portion thereof. Consequently, in the cooled blade according to the present invention, approximately right-angled portions are formed in the vicinity of the air-transpiration holes and the acute-angled portions are essentially eliminated. Thus, even when thermal stress is generated around the air-transpiration holes, concentration of the stress at the inlet/outlet ports of the air-transpiration holes opened in the leading edge portion of the blade is eliminated. As a result, generation of cracks around the air-transpiration holes due to thermal stress can be avoided.
REFERENCES:
patent: 5577889 (1996-11-01), Terazaki et al.
patent: 5813835 (1998-09-01), Corsmeier et al.
patent: 5997251 (1999-12-01), Lee
patent: 57-309 (1982-01-01), None
patent: 61-155601 (1986-07-01), None
patent: 51-77710 (1996-03-01), None
Fukuno Hiroki
Hashimoto Yukihiro
Maeda Shigeyuki
Suenaga Kiyoshi
Tomita Yasuoki
Look Edward K.
McDowell Liam
Mitsubishi Heavy Industries Ltd.
Sughrue Mion Zinn Macpeak & Seas, PLLC
LandOfFree
Gas turbine cooling blade does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Gas turbine cooling blade, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Gas turbine cooling blade will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2546572