Turbine airfoil

Patent metadata

Field	Value
Publication number	US-2016201468-A1
Application number	US-201514595321-A
Country	US
Kind code	A1
Filing date	Jan 13, 2015
Priority date	Jan 13, 2015
Publication date	Jul 14, 2016
Grant date	—

Abstract

The present invention is an aerodynamically efficient turbine airfoil that includes a first endwall, a second endwall, a stacking axis, an aspect ratio, a percentage radial span, a tangential offset, and an angle; wherein relationships between the aspect ratio, percentage radial span, and angle are defined.

First claim

What is claimed is:

1 . A turbine airfoil comprising:
a concave surface, a convex surface, a leading edge, a trailing edge, a first endwall, and a second endwall; wherein: an active length is defined by a distance between the first endwall and the second endwall substantially in a radial direction, an axial width is defined by a distance between the leading edge and the trailing edge substantially in an axial direction at a radial distance of about 50% of the active length, and the active length divided by the axial width defines an aspect ratio AR; and further comprising: a plurality of radially stacked cross sections disposed about and at right angles to a stacking axis disposed substantially in the radial direction between the first endwall and the second endwall; each cross section comprising a portion of the concave surface, convex surface, leading edge, and trailing edge; and further comprising: a first distance Z″ defined as a percentage of the active length disposed between a first cross section and a second cross section, wherein the second cross section is located at substantially the same radial span and coplanar with the first endwall or the second endwall; a second distance Y′ defined as a distance disposed substantially in a tangential direction between a point of intersection between the stacking axis and the first cross section and a point of intersection between the stacking axis and the second cross section; and an angle α, wherein the tangent of α is equal to the second distance Y′ divided by the first distance Z′; and: where AR is equal to or greater than about 3, Z″ is greater than about 3% and less than about 20%, and α is greater than about 8 degrees and less than about 35 degrees; where AR is equal to or greater than about 2 and less than about 3, Z″ is greater than about 3% and less than about 27%, and α is greater than about 8 degrees and less than about 38 degrees; or where AR is equal to or greater than about 1 and less than about 2, Z″ is greater than about 5% and less than about 45%, and α is greater than about 10 degrees and less than about 48 degrees.

2 . The airfoil of claim 1 :
where AR is about 5.0, Z″ is about 5%, and α is about 19 degrees; where AR is about 4.3, Z″ is about 6%, and α is about 19 degrees; where AR is about 3.0, Z″ is about 10%, and α is about 19 degrees; or where AR is about 1.7, Z″ is about 21%, and α is about 28 degrees.

3 . The airfoil of claim 1 , wherein the airfoil is configured as a rotating airfoil and the direction of the tangential offset Y′ is toward the convex surface and away from the concave surface.

4 . The airfoil of claim 1 , wherein the airfoil configured as a rotating airfoil and the second cross section is located at substantially the same radial span and coplanar with the second endwall.

5 . The airfoil of claim 1 , wherein the airfoil configured as a stationary airfoil and the direction of the tangential offset Y′ is toward the convex surface and away from the concave surface.

6 . A steam turbine comprising an axis of rotation and at least one annular steampath defined by an outboard boundary and an inboard boundary between which a plurality of airfoils are arranged tangentially about the axis of rotation and extend radially from the outboard boundary or the inboard boundary; wherein the airfoils each comprise:
a concave surface, a convex surface, a leading edge, a trailing edge, a first endwall, and a second endwall; wherein: an active length is defined by a distance between the first endwall and the second endwall substantially in a radial direction, an axial width is defined by a distance between the leading edge and the trailing edge substantially in an axial direction at a radial distance of about 50% of the active length, and the active length divided by the axial width defines an aspect ratio AR; and further comprising: a plurality of radially stacked cross sections disposed about and at right angles to a stacking axis disposed substantially in the radial direction between the first endwall and the second endwall; each cross section comprising a portion of the concave surface, convex surface, leading edge, and trailing edge; and further comprising: a first distance Z″ defined as a percentage of the active length disposed between a first cross section and a second cross section, wherein the second cross section is located at substantially the same radial span and coplanar with the first endwall or the second endwall; a second distance Y′ defined as a distance disposed substantially in a tangential direction between a point of intersection between the stacking axis and the first cross section and a point of intersection between the stacking axis and the second cross section; and an angle α, wherein the tangent of α is equal to the second distance Y′ divided by the first distance Z′; and: where AR is equal to or greater than about 3, Z″ is greater than about 3% and less than about 20%, and α is greater than about 8 degrees and less than about 35 degrees; where AR is equal to or greater than about 2 and less than about 3, Z″ is greater than about 3% and less than about 27%, and α is greater than about 8 degrees and less than about 38 degrees; or where AR is equal to or greater than about 1 and less than about 2, Z″ is greater than about 5% and less than about 45%, and α is greater than about 10 degrees and less than about 48 degrees.

7 . The steam turbine of claim 6 :
where AR is about 5.0, Z″ is about 5%, and α is about 19 degrees; where AR is about 4.3, Z″ is about 6%, and α is about 19 degrees; where AR is about 3.0, Z″ is about 10%, and α is about 19 degrees; or where AR is about 1.7, Z″ is about 21%, and α is about 28 degrees.

8 . The steam turbine of claim 6 , wherein the airfoils each comprise a rotating airfoil and the direction of the tangential offset Y′ is toward the convex surface and away from the concave surface.

9 . The steam turbine of claim 6 , wherein the airfoils each comprise a rotating airfoil and the second cross section is located at substantially the same radial span and coplanar with the second endwall.

10 . The steam turbine of claim 6 , wherein the airfoils each comprise a stationary airfoil and the direction of the tangential offset Y′ is toward the convex surface and away from the concave surface.

11 . A steam turbine system comprising at least one steam source, at least one expansion section, and at least one condensing section; wherein the at least one expansion section comprises an axis of rotation and at least one annular steampath defined by an outboard boundary and an inboard boundary between which a plurality of airfoils are arranged tangentially about the axis of rotation and extend radially from the outboard boundary or the inboard boundary; wherein the airfoils each comprise:
a concave surface, a convex surface, a leading edge, a trailing edge, a first endwall, and a second endwall; wherein: an active length is defined by a distance between the first endwall and the second endwall substantially in a radial direction, an axial width is defined by a distance between the leading edge and the trailing edge substantially in an axial direction at a radial distance of about 50% of the active length, and the active length divided by the axial width defines an aspect ratio AR; and further comprising: a plurality of radially stacked cross sections disposed about and at right angles to a stacking axis disposed substantially in the radial direction between the first endwall and the second endwall; each cross section comprising a portion of the concave surface, convex surface, leading edge, and trailing edge; and further comprising: a first distance Z″

Assignees

• Gen Electric

Inventors

• Krishnan Prabakaran Modachur
• Cotroneo Joseph Anthony

Classifications

• F05D2220/31

  in steam turbines · CPC title

• F05D2250/712

  concave · CPC title

• F01D5/141 Primary

  Shape, i.e. outer, aerodynamic form (F01D5/148 - F01D5/20 take precedence; blade construction F01D5/147) · CPC title

• F05D2250/711

  convex · CPC title

• F05D2240/12

  Fluid guiding means, e.g. vanes · CPC title