Fluid reaction surfaces (i.e. – impellers) – With heating – cooling or thermal insulation means – Changing state mass within or fluid flow through working...
Reexamination Certificate
1999-05-19
2001-01-23
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
06176677
ABSTRACT:
BACKGROUND OF THE INVENTION
(a) Field of the Invention
The present invention relates to gas turbines, and more particularly to a device for controlling the flow of cooling air through a flowpath in a turbine blade.
(b) Description of Prior Art
In a turbine engine, gases are compressed in a compressor section, burned with fuel in a combustion section and expanded in a turbine section to extract work from the hot, pressurized gases. The rotor assembly of the turbine section includes a disk having a plurality of circumferentially disposed, spaced apart blade attachment slots, each of which is provided with a turbine blade having a root radially disposed therein and spaced from the bottom part of the slot, thus leaving a cavity therebetween.
During operation of the engine, the hot gases impart energy to the rotor assembly. However, the material of the blades can tolerate a maximum temperature beyond which its vulnerability to damage increases, leading to a lower service life.
It is known to cool turbine blades by flowing cooling air extracted from the compressor section. The cooling air is flowed to the cavities formed in the rotor disk through a stator assembly supporting the combustion section and the rotor assembly. From each cavity, the cooling air is flowed through one or more flowpaths in the blade internal core from an inlet opening at the root thereof and exiting through openings provided near the trailing edge of the blade.
A problem which arises with such a configuration is that the amount of cooling air flowing through the blades cannot be adjusted for the amount of cooling air required.
Devices for adjusting the flow of cooling air into turbine blades are known. For example, U.S. Pat. No. 4,626,169 issued to Hosing et al. describes a perforated rectangular cast seal plate, which is disposed in the cavity between the slot and the blade root, against the bottom surface thereof, and which comprises baffles to accommodate a rivet to retain the blade. The seal plate is provided with a coating applied thereon by a flame spraying method and is installed by tapping it with a hammer in the cavity, the coating providing a tight fit between the seal plate and the disk walls defining the cavity.
A problem with such a device is that the casting of the seal plate needs to correspond to the exact dimensions of the cavity and cooperate with the rivet thereof, which requires expensive machining operations. The openings in the plate can also get clogged.
It would be highly desirable to be provided with an inexpensive device that could be easily inserted in the inlet opening of the blade flowpath and be retained therein.
SUMMARY OF THE INVENTION
One aim of the present invention is to provide an inexpensive device that can be easily inserted in the inlet opening of a blade flowpath and retained therein.
In accordance with the present invention there is provided a device for controlling a flow of cooling air through a flowpath in a turbine blade for cooling the turbine blade. The device comprises a plug member for reducing the flow of cooling air through the flowpath. The plug member comprises a blocking portion adapted to be inserted in the flowpath, and a retaining portion joined to the blocking portion for retaining the plug member at an inlet opening of the flowpath, the retaining portion being adapted to engage against walls of the blade forming the flowpath thereof.
The retaining portion may comprise a first flange and a second flange joined to the first flange with the blocking portion.
The blocking portion may comprise a first intermediate panel, a second intermediate panel and a bight portion joining the first and second intermediate panels, the first and second intermediate panels joining the first and second flanges, respectively.
The plug member may be made of a spring metal material.
In accordance with the present invention there is also provided a turbine blade assembly comprising a turbine blade with a root portion defining an inlet opening, and an inner wall defining a flowpath extending from the inlet opening to an outlet opening, provided at an airfoil surface of the turbine blade, for a flow of cooling air, and a device for controlling the flow of cooling air through the flowpath, the device comprising a blocking portion inserted in the inlet opening, and a retaining portion urging against the root portion defining the inlet opening.
In accordance with the present invention, there is further provided a method for adjusting a flow of cooling air through a flowpath in a turbine blade for cooling the turbine blade. The method comprises a) providing a plug member comprising a blocking portion and a retaining portion, and b) inserting the blocking portion in an inlet opening of the flowpath.
In accordance with the present invention, there is further provided a method for adjusting a flow of cooling air through a flowpath having a cross-sectional area in a turbine blade for cooling the turbine blade. The method comprises a) determining a flow of cooling air required through the flowpath, b) cutting a plug member comprising a blocking portion and a retaining portion to a width to reduce the cross-sectional area of the flowpath to the required flow of cooling air, and c) inserting the blocking portion in an inlet opening of the flowpath.
REFERENCES:
patent: 3706508 (1972-12-01), Moskowitz et al.
patent: 3902820 (1975-09-01), Amos
patent: 4242045 (1980-12-01), Grondahl et al.
patent: 4626169 (1986-12-01), Hsing et al.
patent: 5538394 (1996-07-01), Inomata et al.
patent: 850090 (1952-09-01), None
patent: 3131405 (1983-02-01), None
patent: 3306894 (1984-08-01), None
Ch{acute over (e)}vrefils Andr{acute over (e)}
Grigore Daniel Gheorghe
Astle Jeffrey W.
Look Edward K.
McDowell Liam
Pratt & Whitney Canada Corp.
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