High efficiency last stage bucket for steam turbine

• US 7,997,873 B2
• Filed: 03/27/2009
• Issued: 08/16/2011
• Est. Priority Date: 03/27/2009
• Status: Active Grant

• Current Assignee: General Electric Company
• Original Assignee: General Electric Company
• Inventors: McMurray, Timothy S., Slepski, Jonathon E.
• Primary Examiner(s): LOOK, EDWARD K
• Assistant Examiner(s): White; Dwayne J
• Application Number:
  US12/412,655
• Publication Number:
  US 20100247319A1
• Time in Patent Office: 872 Days
• Field of Search: 416/223.A, 416/243, 416/DIG.2, 416/DIG.5
• US Class Current: 416/223.00A
• CPC Class Codes: F01D 5/141 Shape, i.e. outer, aerodynamic form F01D5/148 - F01D5/20 take precedence; blade construction F01D5/147
• CPC Class Codes: F01D 5/225 by shrouding
• CPC Class Codes: F05D 2220/31 in steam turbines
• CPC Class Codes: F05D 2250/74 given by a set or table of xyz-coordinates
• CPC Class Codes: Y10S 416/02 Formulas of curves

Abstract

A turbine bucket including a bucket airfoil having an airfoil shape is provided. The airfoil shape has a nominal profile according to the tables set forth in the specification. The X and Y coordinate are smoothly joined by an arc of radius R defining airfoil profile sections at each distance Z. The profile sections at the Z distances are joined smoothly with one another to form a complete airfoil shape. The airfoil profile results in improved efficiency and airfoil loading capability.

Claims

1. A turbine bucket including a bucket airfoil having an airfoil shape, said airfoil comprising a nominal profile substantially in accordance with Cartesian coordinate values of X, Y and Z and arc coordinate R set forth in Tables 1-19 wherein the X, Y, Z and R distances are in inches, the X and Y coordinate values being smoothly joined by an arc of radius R defining airfoil profile sections at each distance Z, the profile sections at the Z distances being joined smoothly with one another to form a complete airfoil shape.

2. The turbine bucket according to claim 1 forming part of a last stage bucket of a turbine.

3. The turbine bucket according to claim 1, wherein said airfoil shape lies in an envelope within about +/−

0.25 inches in a direction normal to any airfoil surface location.

4. The turbine bucket according to claim 1, wherein the height of the airfoil is about 52 inches.

5. The turbine bucket according to claim 1, wherein a part-span shroud is superimposed on the nominal profile of the airfoil.

6. The turbine bucket according to claim 1, wherein the nominal profile for the airfoil applies in a cold, non-operating condition.

7. The turbine bucket according to claim 1, wherein the nominal profile for the airfoil comprises an uncoated nominal profile.

8. A turbine wheel comprising a plurality of buckets, each of said buckets including an airfoil having an airfoil shape, said airfoil comprising a nominal profile substantially in accordance with Cartesian coordinate values of X, Y and Z and arc coordinate R set forth in Tables 1-19 wherein the X, Y, Z and R distances are in inches, the X and Y coordinate values being smoothly joined by an arc of radius R defining airfoil profile sections at each distance Z, the profile sections at the Z distances being joined smoothly with one another to form a complete airfoil shape.

9. The turbine wheel according to claim 8, wherein said airfoil shape lies in an envelope within about +/−

0.25 inches in a direction normal to any airfoil surface location.

10. The turbine wheel according to claim 8, wherein the nominal profile for the airfoil applies in a cold, non-operating condition.

11. The turbine wheel according to claim 8, wherein the nominal profile for the airfoil comprises an uncoated nominal profile.

12. The turbine wheel according to claim 8, wherein the turbine wheel comprises a last stage of the turbine.

13. The turbine wheel according to claim 8, wherein the turbine wheel includes a plurality buckets wherein a number of buckets employed in the turbine wheel may be altered and the X, Y and R values be appropriately scaled to obtain the desired bucket profile.

14. A turbine comprising a turbine wheel having a plurality of buckets, each of said buckets including an airfoil comprising a nominal profile substantially in accordance with Cartesian coordinate values of X, Y and Z and arc coordinate R set forth in Tables 1-19 wherein the X, Y, Z and R distances are in inches, the X and Y coordinate values being smoothly joined by an arc of radius R defining airfoil profile sections at each distance Z, the profile sections at the Z distances being joined smoothly with one another to form a complete airfoil shape.

15. The turbine according to claim 14, wherein said airfoil shape lies in an envelope within about +/−

0.25 inches in a direction normal to any airfoil surface location.

16. The turbine according to claim 14, wherein the nominal profile for the airfoil applies in a cold, non-operating condition.

17. The turbine according to claim 14, wherein the nominal profile for the airfoil comprises an uncoated nominal profile.

18. The turbine according to claim 14, wherein the turbine wheel comprises a last stage of the turbine.

19. A turbine according to claim 14, wherein the turbine wheel includes a plurality buckets wherein a number of buckets employed in the turbine wheel may be altered and the X, Y and R values be appropriately scaled to obtain the desired bucket profile.

20. A turbine according to claim 19 further comprising:

a bucket having a part-span shroud, said part-span shroud located at a distance of about 45% to about 65% of a total airfoil length from a base of said airfoil.