TURBINE COMPONENT HAVING COOLING PASSAGES WITH VARYING DIAMETER
Systems and devices configured to cool turbine components in a turbine by passing a cooling flow through the turbine component via a cooling passage with a variable diameter are disclosed. In one embodiment, a turbine component includes: at least one elongated cooling passage extending from a root of the bucket to a tip of the bucket, wherein the elongated cooling passage has a variable diameter along a length of the bucket.
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The subject matter disclosed herein relates to cooling passages in turbine components, more specifically, to turbine nozzles, shrouds, and/or buckets having shaped tube electrochemical machined (STEM) cooling holes with a varying diameter (e.g., a convergent shape, a divergent shape, etc.) therein.
In some turbines (e.g., gas turbines), efficiencies are directly proportional to the temperature of turbine gases flowing along the hot gas path and driving the turbine blades. These gas turbines typically have operating temperatures on the order of approximately 2700 degrees Fahrenheit (1482 degrees Celsius), a temperature which may stress and/or damage turbine components (e.g., turbine buckets, shrouds, nozzles, etc.). To withstand these high temperatures, the components are manufactured from advanced materials and typically include smooth bore cooling passages with a constant diameter for flowing a cooling medium, typically compressor discharge air, through the buckets. These passages also typically extend from the radially inner bucket root to the radially outer bucket tip with a consistent diameter.
Many power generation turbine buckets use Shaped Tube Electrochemical Machining (STEM) drilled circular round holes to form the radial cooling flow passages inside the turbine airfoils. STEM is used for non-contact drilling of small, deep holes in electrically conductive materials, with high aspect ratios (e.g., a ratio of the length or depth of the hole to the largest lateral dimension (e.g., diameter of the hole), which in certain specific applications can be as small as a few millimeters) such as 300:1. The STEM process removes stock by electrolytic dissolution, utilizing a flow of electric current between an electrode and the workpiece through an electrolyte flowing in the intervening space to form the radial cooling flow passages.
While smooth-bore passages have been utilized, turbulence promoters, (e.g., turbulators), are also used in many gas turbine buckets to enhance the internal heat transfer coefficient. This heat transfer enhancement may increase the heat transfer coefficient to more than two times greater than smooth-bore passages for the same cooling flow rate. Turbulators conventionally comprise internal ridges or roughened surfaces along the interior surfaces of the cooling passages. However, formation of these smooth-bore passages and/or turbulators may be limited by wall thickness requirements within the turbine bucket, particularly in proximity to a tip and/or trailing edge of the turbine bucket which typically has very small/thin dimensions. These limitations result in the smooth-bore passages having a small diameter near root sections of the turbine bucket so as to meet wall thickness requirements in the tip.
BRIEF DESCRIPTION OF THE INVENTIONTurbine components (e.g., turbine nozzles, shrouds, and/or buckets) having shaped tube electrochemical machined (STEM) cooling holes with a varying diameter (e.g., a convergent shape, a divergent shape, etc.) are disclosed.
A first aspect of the invention includes: a turbine component including: at least one elongated cooling passage extending from a root of the bucket to a tip of the bucket, wherein the elongated cooling passage has a variable diameter along a length of the bucket.
A second aspect of the invention includes: turbine bucket including: a root configured to connect to a turbine; a base disposed on the root and configured to extend into a turbine flowpath, the base having an airfoil shape and including a tip; and at least one elongated cooling passage formed in the root and the base, the at least one elongated cooling pass including: a first section disposed proximate the root and including an aperture at a terminus of the at least one elongated cooling passage, the first section extending into the base, and a second section fluidly connected to the first section and disposed proximate the tip, wherein a second diameter of the second section is smaller than a first diameter of the first section.
A third aspect of the invention includes: a turbine including: a stator; a working fluid passage substantially surrounded by the stator; a rotor disposed radially inboard of the stator and in the working fluid passage; and a turbine bucket connected to the rotor, the turbine bucket including: at least one elongated cooling passage extending from a root of the turbine bucket to a tip of the turbine bucket, wherein the elongated cooling passage has a variable diameter along a length of the turbine bucket.
These and other features of this invention will be more readily understood from the following detailed description of the various aspects of the invention taken in conjunction with the accompanying drawings that depict various embodiments of the invention, in which:
It is noted that the drawings of the invention are not necessarily to scale. The drawings are intended to depict only typical aspects of the invention, and therefore should not be considered as limiting the scope of the invention. It is understood that elements similarly numbered between the FIGURES may be substantially similar as described with reference to one another. Further, in embodiments shown and described with reference to
Aspects of the invention provide for turbine components (e.g., nozzles, shrouds, buckets, etc.) having STEM shaped cooling passages with a varying diameter (e.g., convergent, divergent, etc.).
As noted herein, cooling passages through turbine components are conventionally cylindrical passageways with a substantially constant diameter from root to tip. The diameter of the coolant passages is constant and is therefore limited by the thinnest part of the turbine component (e.g., the blade tip, the trailing edge, the nozzle trailing edge, etc.).
In contrast to conventional approaches, aspects of the invention include a turbine component (e.g., turbine bucket, turbine nozzle, nozzle trailing edge, shroud, etc.) having cooling passages with a varying diameter (e.g., a cooling passage which has a first diameter in one portion of the turbine bucket which varies in dimensional size from a second diameter of the cooling passage in a second portion of the turbine bucket, convergent cooling passages, divergent cooling passages, etc.). In an embodiment, the cooling passage diameter may decrease/diminish (e.g., gradually, telescopically, stepwise, etc.) across a length of the cooling passage in a convergent manner. In one embodiment, the varying diameter of the cooling passage has a larger dimension proximate a root of a turbine component (e.g., bucket) relative to a diameter of the cooling passage proximate a tip of the turbine bucket (e.g., a small diameter cooling passage proximate the tip of the turbine bucket which has an increasingly larger diameter as the cooling passage extends through mid and lower points of an airfoil span of the turbine bucket). The thickness/diameter of the cooling passage may be greater at the turbine bucket root where a cooling fluid flow may be introduced, this thickness increasing the sectional area proximate the root and increasing flow of the cooling fluid there through. In an embodiment, the cooling passage may include an aperture (e.g., metering feature) through the nozzle trailing edge configured to manipulate/control characteristics of a cooling flow through the cooling passage.
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As used herein, the terms “axial” and/or “axially” refer to the relative position/direction of objects along axis A, which is substantially perpendicular to the axis of rotation of the turbomachine (in particular, the rotor section). As further used herein, the terms “radial” and/or “radially” refer to the relative position/direction of objects along axis (r), which is substantially perpendicular with axis A and intersects axis A at only one location. Additionally, the terms “circumferential” and/or “circumferentially” refer to the relative position/direction of objects along a circumference which surrounds axis A but does not intersect the axis A at any location.
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In an embodiment, a technician may increase (e.g., drill, bore, STEM, etc.) a diameter of metering feature 712 and/or aperture 716 in order to adjust the heat transfer coefficient within cooling passage 710. In another embodiment, shown in
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The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the disclosure. As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises” and/or “comprising,” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof
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 have 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 languages of the claims.
Claims
1. A turbine component comprising:
- a base portion; and
- at least one elongated cooling passage extending from a root of the base portion to a tip of the base portion, wherein the elongated cooling passage has a variable diameter along a length of the turbine component.
2. The turbine component of claim 1, wherein the at least one elongated cooling passage includes a Shaped Tube Electrochemical Machining (STEM) drilled passage.
3. The turbine component of claim 1, wherein a diameter of the at least one elongated cooling passage varies incrementally between the root of the turbine component and the tip of the turbine component.
4. The turbine component of claim 1, wherein the at least one elongated cooling passage has a frusto-conical shape.
5. The turbine component of claim 1, wherein the at least one elongated cooling passage includes:
- a first section proximate the root, the first section having a first diameter, and a second section fluidly connected to the first section, the second section located proximate the tip and having a second diameter.
6. The turbine component of claim 5, wherein the first diameter is larger than the second diameter.
7. The turbine component of claim 1, wherein the at least one elongated cooling passage includes at least one turbulator disposed on a surface of the elongated cooling passage.
8. The turbine component of claim 7, wherein the at least one turbulator includes at least one of: a segmented turbulator and a swirl shaped turbulator.
9. The turbine component of claim 1, wherein the at least one elongated cooling passage includes a metering feature disposed substantially proximate the tip of the turbine component.
10. A turbine bucket comprising:
- a root configured to connect to a turbine;
- a base disposed on the root and configured to extend into a turbine flowpath, the base having an airfoil shape and including a tip; and
- at least one elongated cooling passage formed in the root and the base, the at least one elongated cooling pass including: a first section disposed proximate the root and including an aperture at a terminus of the at least one elongated cooling passage, the first section extending into the base, and a second section fluidly connected to the first section and disposed proximate the tip, wherein a second diameter of the second section is smaller than a first diameter of the first section.
11. The turbine bucket of claim 10, wherein the at least one elongated cooling passage includes a Shaped Tube Electrochemical Machining (STEM) drilled passage.
12. The turbine bucket of claim 10, wherein a diameter of the at least one elongated cooling passage varies incrementally throughout the first section and the second section.
13. The turbine bucket of claim 10, wherein the at least one elongated cooling passage has a frusto-conical shaped passage and includes a metering feature.
14. The turbine bucket of claim 10, wherein the first diameter is larger than the second diameter.
15. The turbine bucket of claim 10, wherein the at least one elongated cooling passage includes at least one turbulator disposed on a surface of the elongated cooling passage.
16. The turbine bucket of claim 10, wherein the at least one turbulator includes at least one of: a segmented turbulator and a swirl shaped turbulator.
17. A turbine comprising:
- a stator;
- a working fluid passage substantially surrounded by the stator;
- a rotor disposed radially inboard of the stator and in the working fluid passage; and
- a turbine bucket connected to the rotor, the turbine bucket including: at least one elongated cooling passage extending from a root of the turbine bucket to a tip of the turbine bucket, wherein the elongated cooling passage has a variable diameter along a length of the turbine bucket.
18. The turbine of claim 17, wherein the at least one elongated cooling passage is a frusto-conical shaped passage and includes a metering feature disposed substantially proximate a tip of the turbine bucket.
19. The turbine of claim 17, wherein the at least one elongated cooling passage includes:
- a first section proximate the root, the first section having a first diameter, and
- a second section fluidly connected to the first section, the second section having a second diameter and proximate the tip, wherein the first diameter is larger than the second diameter.
20. The turbine of claim 17, wherein the at least one elongated cooling passage includes at least one turbulator disposed on a surface of the elongated cooling passage, the at least one turbulator includes at least one of: a segmented turbulator and a swirl shaped turbulator.
Type: Application
Filed: Dec 11, 2012
Publication Date: Jun 12, 2014
Applicant: General Electric Company (Schenectady, NY)
Inventors: Xiuzhang James Zhang (Simpsonville, SC), Adebukola Oluwaseun Benson (Simpsonville, SC), Richard Ryan Pilson (Greer, SC), Stephen William Tesh (Simpsonville, SC)
Application Number: 13/711,241
International Classification: F01D 5/18 (20060101);