AIRFOIL AND METHOD FOR MANUFACTURING AN AIRFOIL
An airfoil includes a pressure side, a suction side opposed to the pressure side, a cavity inside the airfoil between the pressure and suction sides, and a trailing edge downstream from the cavity between the pressure and suction sides. A first set of cooling passages through the trailing edge provide fluid communication from the cavity through the trailing edge. A first divider across each cooling passage in the first set of cooling passages extends from the pressure side to the suction side at the trailing edge.
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The present invention generally involves an airfoil and a method for manufacturing an airfoil.
BACKGROUND OF THE INVENTIONTurbines are widely used in industrial and commercial operations. A typical commercial steam or gas turbine used to generate electrical power includes alternating stages of stationary and rotating airfoils. For example, stationary vanes may be attached to a stationary component such as a casing that surrounds the turbine, and rotating blades may be attached to a rotor located along an axial centerline of the turbine. A compressed working fluid, such as but not limited to steam, combustion gases, or air, flows through the turbine, and the stationary vanes accelerate and direct the compressed working fluid onto the subsequent stage of rotating blades to impart motion to the rotating blades, thus turning the rotor and performing work or generating thrust.
The efficiency of the turbine generally increases with increased temperatures of the compressed working fluid. However, excessive temperatures within the turbine may reduce the longevity of the airfoils in the turbine and thus increase repairs, maintenance, and outages associated with the turbine. As a result, various designs and methods have been developed to provide cooling to the airfoils. For example, a cooling media may be supplied to a cavity inside the airfoil to convectively and/or conductively remove heat from the airfoil. In particular embodiments, the cooling media may flow out of the cavity through cooling passages in the airfoil to provide film cooling over the outer surface of the airfoil.
The cavity and cooling passages in the airfoil may be manufactured using an investment casting process commonly referred to as a lost wax process. The lost wax process uses a ceramic core to define the cavity inside the airfoil. A wax is applied over the ceramic core, and the wax surface is shaped into the desired curvature for the airfoil. The wax-covered ceramic core is then repeatedly dipped into a liquid ceramic solution to create a ceramic shell over the wax surface. The wax may then be heated to remove the wax from between the ceramic core and the ceramic shell, creating a void between the ceramic core and the ceramic shell that serves as a mold for the airfoil. Molten metal may then be poured into the mold to form the airfoil. After the metal cools and solidifies, the ceramic shell may be broken and removed, exposing the metal that has taken the shape of the void created by the removal of the wax. The ceramic core may then be dissolved to produce the airfoil with the cavity and cooling passages.
Various efforts have been attempted to reduce the amount of cooling media flowing through the airfoil. For example, reducing the size and/or width of the cooling passages may enhance heat transfer to the cooling media while also reducing the amount of cooling media flowing through the airfoil. However, the smaller cooling passages require correspondingly smaller projections from the ceramic core that are sensitive to damage during the casting process. In particular, the projections from the ceramic core near either end of the ceramic core are susceptible to breaking off during casting. In an effort to strengthen the ceramic core while still providing smaller cooling passages, the projections from the ceramic core may be larger at either end and narrower in the middle. However, the larger projections may result in uneven cooling media flow through the correspondingly larger cooling passages, depriving the smaller cooling passages in the middle of the airfoil of sufficient cooling media flow. Accordingly, an airfoil and method for manufacturing an airfoil that produces a desired cooling media flow profile through cooling passages in the airfoil would be useful.
BRIEF DESCRIPTION OF THE INVENTIONAspects and advantages of the invention are set forth below in the following description, or may be obvious from the description, or may be learned through practice of the invention.
One embodiment of the present invention is an airfoil that includes a pressure side, a suction side opposed to the pressure side, a cavity inside the airfoil between the pressure and suction sides, and a trailing edge downstream from the cavity between the pressure and suction sides. A first set of cooling passages through the trailing edge provide fluid communication from the cavity through the trailing edge. A first divider across each cooling passage in the first set of cooling passages extends from the pressure side to the suction side at the trailing edge.
Another embodiment of the present invention is an airfoil that includes a pressure side, a suction side opposed to the pressure side, a cavity inside the airfoil between the pressure and suction sides, and a trailing edge downstream from the cavity between the pressure and suction sides. A first set of cooling passages through the trailing edge provide fluid communication from the cavity through the trailing edge. A first set of pins extend across each cooling passage in the first set of cooling passages upstream from the trailing edge.
The present invention may also include an airfoil having a pressure side, a suction side opposed to the pressure side, a cavity inside the airfoil between the pressure and suction sides, and a trailing edge downstream from the cavity between the pressure and suction sides. A first set of cooling passages through the trailing edge provide fluid communication from the cavity through the trailing edge. A second set of cooling passages through the trailing edge provide fluid communication from the cavity through the trailing edge, and the first set of cooling passages are wider than the second set of cooling passages. The airfoil further includes first means for reducing flow through the first set of cooling passages.
Those of ordinary skill in the art will better appreciate the features and aspects of such embodiments, and others, upon review of the specification.
A full and enabling disclosure of the present invention, including the best mode thereof to one skilled in the art, is set forth more particularly in the remainder of the specification, including reference to the accompanying figures, in which:
Reference will now be made in detail to present embodiments of the invention, one or more examples of which are illustrated in the accompanying drawings. The detailed description uses numerical and letter designations to refer to features in the drawings. Like or similar designations in the drawings and description have been used to refer to like or similar parts of the invention. As used herein, the terms “first”, “second”, and “third” may be used interchangeably to distinguish one component from another and are not intended to signify location or importance of the individual components. In addition, the terms “upstream” and “downstream” refer to the relative location of components in a fluid pathway. For example, component A is upstream from component B if a fluid flows from component A to component B. Conversely, component B is downstream from component A if component B receives a fluid flow from component A.
Each example is provided by way of explanation of the invention, not limitation of the invention. In fact, it will be apparent to those skilled in the art that modifications and variations can be made in the present invention without departing from the scope or spirit thereof. For instance, features illustrated or described as part of one embodiment may be used on another embodiment to yield a still further embodiment. Thus, it is intended that the present invention covers such modifications and variations as come within the scope of the appended claims and their equivalents.
Various embodiments of the present invention include an airfoil and a method for manufacturing an airfoil. The airfoil generally includes a pressure side having a concave curvature, a suction side having a convex curvature and opposed to the pressure side, a cavity inside the airfoil between the pressure and suction sides, and a trailing edge downstream from the cavity between the pressure and suction sides. The airfoil further includes one or more sets of cooling passages through the trailing edge that provide fluid communication from the cavity through the trailing edge. One or more of the sets of cooling passages may include various means for reducing flow through the cooling passages. In particular embodiments, for example, the means may include one or more dividers across some of the cooling passages at the trailing edge. In other particular embodiments, the means may include a set of pins that extend across some of the cooling passages. Although exemplary embodiments of the present invention will be described generally in the context of an airfoil incorporated into a turbine, one of ordinary skill in the art will readily appreciate from the teachings herein that embodiments of the present invention are not limited to a turbine unless specifically recited in the claims.
Referring now to the drawings, wherein identical numerals indicate the same elements throughout the figures,
The cooling passages 20 may be arranged in multiple sets, with each set of cooling passages 20 having a different size, shape, and/or width. For example, a first set of cooling passages 22 located at the top and bottom of the trailing edge 18 may have a larger size and/or width than a second set of cooling passages 24 located in the middle of the trailing edge 18. In the particular embodiment shown in
The difference in size, shape, and/or width between the first and second sets of cooling passages 22, 24 would ordinarily create an undesirable disparity in cooling media flow along the length of the trailing edge 18. Specifically, the larger size and/or width of the first set of cooling passages 22 would result in more cooling media flowing through the first set of cooling passages 22, possibly resulting in insufficient cooling media flow through the second set of cooling passages 24. To reduce this disparity, the first set of cooling passages 22 may further include means for reducing flow through the first set of cooling passages 22. In the particular embodiment shown in
The core 40 may be manufactured from any material having sufficient strength to withstand the high temperatures associated with the casting material (e.g., a high alloy metal) while maintaining tight positioning required for the core 40 during casting. For example, the core 40 may be cast from ceramic material, ceramic composite material, or other suitable materials. Once cast or otherwise manufactured, a laser, electron discharge machine, drill, water jet, or other suitable device may be used to refine or form the serpentine portion 42, projections 44, and/or notches 50 shown in
The difference in size, shape, and/or width between the first, second, and third sets of cooling passages 22, 24, 26 would ordinarily create an undesirable disparity in cooling media flow along the length of the trailing edge 18. Specifically, the larger size and/or width of the first and second sets of cooling passages 22, 24 would result in more cooling media flowing through the first and second sets of cooling passages 22, 24, possibly resulting in insufficient cooling media flow through the third set of cooling passages 26. To reduce this disparity, the first and/or second sets of cooling passages 22, 24 may further include means for reducing flow through the respective cooling passages 20. In the particular embodiment shown in
As shown most clearly in
As shown most clearly in
This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they include structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal language of the claims.
Claims
1. An airfoil, comprising:
- a. a pressure side;
- b. a suction side opposed to the pressure side;
- c. a cavity inside the airfoil between the pressure and suction sides;
- d. a trailing edge downstream from the cavity between the pressure and suction sides;
- e. a first set of cooling passages through the trailing edge, wherein the first set of cooling passages provide fluid communication from the cavity through the trailing edge; and
- f. a first divider across each cooling passage in the first set of cooling passages, wherein each first divider extends from the pressure side to the suction side at the trailing edge.
2. The airfoil as in claim 1, further comprising a plurality of first dividers across each cooling passage in the first set of cooling passages.
3. The airfoil as in claim 1, further comprising a second set of cooling passages through the trailing edge, wherein the second set of cooling passages provide fluid communication from the cavity through the trailing edge, and the first set of cooling passages are wider than the second set of cooling passages.
4. The airfoil as in claim 3, further comprising a third set of cooling passages through the trailing edge, wherein the third set of cooling passages provide fluid communication from the cavity through the trailing edge, and the second set of cooling passages are wider than the third set of cooling passages.
5. The airfoil as in claim 3, further comprising a second set of pins that extend across each cooling passage in the second set of cooling passages upstream from the trailing edge.
6. The airfoil as in claim 5, wherein the second set of pins are axially staggered inside each cooling passage in the second set of cooling passages.
7. The airfoil as in claim 3, further comprising a second divider across each cooling passage in the second set of cooling passages, wherein each second divider extends from the pressure side to the suction side at the trailing edge.
8. The airfoil as in claim 7, wherein each first divider is wider than each second divider.
9. The airfoil as in claim 1, wherein the first set of cooling passages are axially tapered.
10. An airfoil, comprising:
- a. a pressure side;
- b. a suction side opposed to the pressure side;
- c. a cavity inside the airfoil between the pressure and suction sides;
- d. a trailing edge downstream from the cavity between the pressure and suction sides;
- e. a first set of cooling passages through the trailing edge, wherein the first set of cooling passages provide fluid communication from the cavity through the trailing edge; and
- f. a first set of pins that extend across each cooling passage in the first set of cooling passages upstream from the trailing edge.
11. The airfoil as in claim 10, wherein the first set of pins are axially staggered inside each cooling passage in the first set of cooling passages.
12. The airfoil as in claim 10, further comprising a second set of cooling passages through the trailing edge, wherein the second set of cooling passages provide fluid communication from the cavity through the trailing edge, and the first set of cooling passages are wider than the second set of cooling passages.
13. The airfoil as in claim 12, further comprising a third set of cooling passages through the trailing edge, wherein the third set of cooling passages provide fluid communication from the cavity through the trailing edge, and the second set of cooling passages are wider than the third set of cooling passages.
14. The airfoil as in claim 12, further comprising a second set of pins that extend across each cooling passage in the second set of cooling passages upstream from the trailing edge.
15. The airfoil as in claim 12, further comprising a second divider across each cooling passage in the second set of cooling passages, wherein each second divider extends from the pressure side to the suction side at the trailing edge.
16. The airfoil as in claim 10, wherein the first set of cooling passages are axially tapered.
17. An airfoil, comprising:
- a. a pressure side;
- b. a suction side opposed to the pressure side;
- c. a cavity inside the airfoil between the pressure and suction sides;
- d. a trailing edge downstream from the cavity between the pressure and suction sides;
- e. a first set of cooling passages through the trailing edge, wherein the first set of cooling passages provide fluid communication from the cavity through the trailing edge;
- f. a second set of cooling passages through the trailing edge, wherein the second set of cooling passages provide fluid communication from the cavity through the trailing edge, and the first set of cooling passages are wider than the second set of cooling passages; and
- g. first means for reducing flow through the first set of cooling passages.
18. The airfoil as in claim 17, further comprising second means for reducing flow through the second set of cooling passages.
19. The airfoil as in claim 17, further comprising a third set of cooling passages through the trailing edge, wherein the third set of cooling passages provide fluid communication from the cavity through the trailing edge, and the second set of cooling passages are wider than the third set of cooling passages.
20. The airfoil as in claim 17, wherein the first set of cooling passages are axially tapered.
Type: Application
Filed: Aug 31, 2012
Publication Date: Mar 6, 2014
Applicant: GENERAL ELECTRIC COMPANY (Schenectady, NY)
Inventors: Mark Andrew Jones (Greer, SC), Aaron Ezekiel Smith (Simpsonville, SC), Harika Senem Kahveci (Greenville, SC)
Application Number: 13/600,717
International Classification: F01D 5/18 (20060101);