Film cooling for a closed loop cooled airfoil

• US 6,506,013 B1
• Filed: 04/28/2000
• Issued: 01/14/2003
• Est. Priority Date: 04/28/2000
• Status: Expired due to Term

• Current Assignee: General Electric Company
• Original Assignee: General Electric Company
• Inventors: Yu, Yufeng Phillip, Itzel, Gary Michael, Burdgick, Steven Sebastian
• Primary Examiner(s): Lopez, F. Daniel
• Assistant Examiner(s): McAleenan, James M
• Application Number:
  US09/561,865
• Time in Patent Office: 991 Days
• Field of Search: 415/115, 415/116, 415/176, 416/96.A, 416/96.R
• US Class Current: 415/115
• CPC Class Codes: F01D 5/186 Film cooling F01D5/187 takes precedence
• CPC Class Codes: F01D 5/188 with an insert in the blade cavity to guide the cooling fluid, e.g. forming a separation wall
• CPC Class Codes: F05D 2260/201 by impingement of a fluid
• CPC Class Codes: F05D 2260/202 by film cooling
• CPC Class Codes: F05D 2260/205 Cooling fluid recirculation, i.e. after cooling one or more components is the cooling fluid recovered and used elsewhere for other purposes
• CPC Class Codes: F05D 2260/2322 steam

Abstract

Turbine stator vane segments have radially inner and outer walls with vanes extending therebetween. The inner and outer walls are compartmentalized and have impingement plates. Steam flowing into the outer wall plenum passes through the impingement plate for impingement cooling of the outer wall upper surface. The spent impingement steam flows into cavities of the vane having inserts for impingement cooling the walls of the vane. The steam passes into the inner wall and through the impingement plate for impingement cooling of the inner wall surface and for return through return cavities having inserts for impingement cooling of the vane surfaces. At least one film cooling hole is defined through a wall of at least one of the cavities for flow communication between an interior of the cavity and an exterior of the vane. The film cooling hole(s) are defined adjacent a potential low LCF life region, so that cooling medium that bleeds out through the film cooling hole(s) reduces a thermal gradient in a vicinity thereof, thereby the increase the LCF life of that region.

Claims

1. A turbine vane segment, comprising:

inner and outer walls spaced from one another;

a vane extending between said inner and outer walls and having leading and trailing edges, said vane including a plurality of discrete cavities between the leading and trailing edges and extending lengthwise of said vane for flowing a steam therethrough;

said outer wall defining at least one steam plenum;

said inner wall defining at least one steam plenum;

a steam inlet enabling passage of the steam into said plenum of said outer wall;

said vane having a first opening communicating said plenum of said outer wall with at least one of said cavities to enable passage of the steam between said one plenum and said one cavity, said vane having a second opening communicating said one cavity with said steam plenum of said inner wall, and said vane having a third opening communicating said steam plenum of said inner wall with at least another of said cavities to enable passage of the cooling medium in a substantially closed circuit between said steam plenum of said outer wall, said one cavity, said steam plenum of said inner wall, and said another cavity;

an insert sleeve within each of said one cavity and said another cavity and spaced from interior wall surfaces thereof, each said insert sleeve having an inlet for flowing the steam into said insert sleeve, each said insert sleeve having a plurality of openings therethrough for flowing the steam through said sleeve openings into said space between said sleeve and said interior wall surfaces for impingement against said interior wall surface of said vane; and

at least one film cooling hole defined through a wall of at least one of said one and another cavities for flow communication between an interior of said cavity and an exterior surface of the vane, said at least one film cooling hole being defined adjacent a predetermined potential low LCF life region, whereby a portion of the steam flowing through said vane bleeds out through said at least one film cooling hole to reduce a thermal gradient in a vicinity thereof, thereby to increase the Low Cycle Fatigue ( LCF) life of said region, a remainder of the walls of each of said cavities being free from film cooling holes.

2. A turbine vane segment according to claim 1, wherein said inner wall has at least one rib along an inner surface thereof defining inner compartments inwardly of said inner surface;

and further comprising;

a cover for said inner compartments spaced from said inner surface, an impingement plate between said cover and said inner surface, said second opening of said vane being in communication with said plenum of said inner wall to enable passage of the steam, said impingement plate having openings enabling passage of the steam for impingement cooling of said inner wall.

3. A turbine vane segment according to claim 1, wherein one of said plurality of discrete cavities comprises a trailing edge cavity having a plurality of openings through the trailing edge of said vane for flowing air from said trailing edge cavity through said openings to an exterior of said vane.

4. A turbine vane segment as in claim 1, wherein said at least one film cooling hole is defined at an angle to the wall of the vane so that steam flowing therethrough is directed to the exterior of the vane in a downstream direction.

5. A turbine vane segment as in claim 1, wherein there are a plurality of film cooling holes defined through said wall.

6. A turbine vane segment as in claim 5, wherein said plurality of film cooling holes are defined in a substantially linear array that extends along at least a part of a length of the vane.

7. A turbine vane segment as in claim 6, wherein said linear array extends from adjacent said outer wall of said vane.

8. A stator vane segment, comprising:

inner and outer walls spaced from one another;

a vane extending between said inner and outer walls and having leading and trailing edges, said vane including a plurality of discrete cavities between the leading and trailing edges and extending lengthwise of said vane;

said inner and outer walls defining respective plenums and an impingement plate in each said plenum, an inlet into said outer wall for flowing steam into the outer wall plenum and through the impingement plate in said outer wall plenum for impingement steam cooling an upper surface of said outer wall;

an insert in one of said cavities for receiving spent impingement steam from said outer wall and having impingement openings for directing the steam received from said outer wall against interior wall surfaces of said one cavity for impingement cooling of the vane about said one cavity;

said inner wall having an opening for receiving the spent impingement steam from said one cavity into the inner wall plenum for flow through the impingement plate therein and impingement cooling of the inner wall;

an insert in another of said cavities for receiving spent impingement steam from said inner wall and having impingement openings for directing the steam received from said inner wall against interior wall surfaces of said another cavity for impingement cooling of the vane about said another cavity;

an outlet for receiving the spent impingement steam from said another cavity, whereby the steam flow through said inner and outer walls, said one cavity and said another cavity constitutes a substantially closed flow circuit through said vane; and

at least one film cooling hole defined through a wall of at least one of said one cavity and said another cavity for flow communication between an interior of said at least one cavity and an exterior of the vane, said at least one film cooling hole being defined substantially solely proximate a predetermined potential low Low Cycle Fatigue (LCF) life region of the vane, wherein a portion of the cooling steam flowing into said at least one cavity bleeds out of said cavity through said at least one film cooling hole to an exterior of said vane for flowing along at least a portion of an exterior surface of said vane downstream from said film cooling hole to define a cooling film for cooling an exterior surface of said vane downstream thereof, thereby to increase an LCF life thereof.

9. A turbine vane segment according to claim 8, further comprising a trailing edge cavity through said vane for receiving air from an air inlet and passing the air through openings in the trailing edge for cooling the trailing edge.

10. A vane segment as in claim 8, wherein said at least one film cooling hole is defined at an angle to the wall of the vane so that steam flowing therethrough is directed to the exterior of the vane in a downstream direction.

11. A vane segment as in claim 10, wherein there are a plurality of film cooling holes defined through said wall.

12. A vane segment as in claim 11, wherein said plurality of film cooling holes are defined in a substantially linear array that extends along at least a part of a length of the vane.

13. A vane segment as in claim 12, wherein said linear array extends from adjacent said outer wall of said vane.

14. A method of increasing the Low Cycle Fatigue (LCF) life of a stator vane segment forming part of a stage of a turbine comprising:

providing a stator being segment including;

inner and outer walls spaced from one another;

a stator vane extending between said inner and outer walls and having leading and trailing edges, said vane including a plurality of discrete cavities between the leading and trailing edges and extending lengthwise of said vane for flowing steam in a substantially closed circuit through said vane; and

at least one film cooling hole defined through a wall of at least one said cavity for flow communication between an interior of said cavity and an exterior of the vane, said at least one film cooling hole being defined adjacent a predetermined potential low Low Cycle Fatigue (LCF) life region,

flowing steam through at least two of said plurality of discrete cavities to cool said stator vane and

bleeding a portion of the steam flowing through said vane out through said at least one film cooling hole to reduce a thermal gradient in a vicinity thereof, thereby the increase the LCF life of said region.

15. A method as in claim 14, wherein an insert sleeve is disposed within said at least one cavity and spaced from the inner wall of said vane to define a gap therebetween, said insert sleeve having a plurality of openings therethrough, said flowing step comprising flowing steam into an inlet of said insert and through said openings in said sleeve for impingement against an inner wall surface of said vane.

16. A method as in claim 14, wherein said at least one film cooling hole is defined at an angle to the wall of the vane and wherein said bleeding step comprises bleeding steam through said at least one film cooling hole toward the exterior of the vane in a downstream direction.

17. A method as in claim 14, wherein there are a plurality of film cooling holes disposed in the linear array and extending from adjacent said outer wall of said vane for cooling a radially outer portion of said vane.

18. A method as in claim 14, wherein said outer wall defines at least one steam plenum and said inner wall defines at least one steam plenum and wherein said steam flows from said outer wall steam plenum through said at least one cavity to said inner wall steam plenum and through another said cavity toward said radial outer wall.