Airfoil design having localized suction side curvatures

Patent metadata

Field	Value
Publication number	US-9957801-B2
Application number	US-201213566400-A
Country	US
Kind code	B2
Filing date	Aug 3, 2012
Priority date	Aug 3, 2012
Publication date	May 1, 2018
Grant date	May 1, 2018

Abstract

An airfoil for a gas turbine engine comprises a radially extending body having a transverse cross-section. The transverse cross-section comprises a leading edge, a trailing edge, a pressure side and a suction side. The pressure side extends between the leading edge and the trailing edge with a predominantly concave curvature. The suction side extends between the leading edge and the trailing edge with a predominantly convex curvature. The suction side includes an approximately flat portion flanked by forward and aft convex portions. In another embodiment, the suction side includes a series of local curvature changes that produce inflection points in the convex curvature of the suction side spaced from the trailing edge.

First claim

The invention claimed is:

1. An airfoil for a gas turbine engine, the airfoil comprising:
a radially extending body having a transverse cross-section comprising:
a leading edge extending from a pressure side to a suction side;
a trailing edge extending from the pressure side to the suction side;
the pressure side extending between the leading edge and the trailing edge with a predominantly concave curvature; and
the suction side extending between the leading edge and the trailing edge with a predominantly convex curvature, the suction side comprising:
a forward portion aft of the leading edge,
an aft portion forward of the trailing edge, and
a generally flat portion extending from the forward portion to the aft portion, wherein the forward portion has positive curvature from the leading edge to the point at which it meets the generally flat portion, and wherein the aft portion has positive curvature from the point at which it meets the generally flat portion to the trailing edge.

2. The airfoil of claim 1 wherein the generally flat portion is formed by a series of local curvature changes that produce inflection points in the convex curvature of the suction side.

3. The airfoil of claim 1 wherein the generally flat portion is defined by a plurality of changes in sign of the second derivative of a curve defining the suction side.

4. The airfoil of claim 1 wherein the radially extending body defines a chord length and wherein the generally flat portion spans a mid-chord point of the airfoil on the suction side.

5. The airfoil of claim 4 wherein the generally flat portion joins the forward portion at the mid-chord point of the airfoil.

6. The airfoil of claim 1 wherein the generally flat portion joins the forward portion at a throat of the airfoil.

7. The airfoil of claim 1 wherein the generally flat portion includes a plurality of small segments having local concave and convex curvatures less curved than the forward and aft portions.

8. The airfoil of claim 1 wherein the aft portion extends from the trailing edge to a point within a trailing edge region of the airfoil comprising approximately an aft twenty-five percent of a chord length of the airfoil.

9. The airfoil of claim 1 and further comprising one or more arrays of cooling holes extending along the suction side aft of the forward convex portion of the airfoil.

10. The airfoil of claim 1 wherein the radially extending body comprises a turbine vane or a turbine blade.

11. A turbine stage for a gas turbine engine, the turbine stage comprising:
an array of airfoils, each airfoil comprising a radially extending body having a transverse cross-section comprising:
a leading edge extending from a pressure side to a suction side;
a trailing edge extending from the pressure side to the suction side;
a chord length extending between the leading edge and the trailing edge;
the pressure side extending between the leading edge and the trailing edge with a predominantly concave curvature; and
the suction side extending between the leading edge and the trailing edge with a predominantly convex curvature that includes a forward portion aft of the leading edge having positive curvature, an aft portion forward of the trailing edge having positive curvature, and an intermediate portion extending from the forward portion to the aft portion, wherein the intermediate portion has a series of local curvature changes such that regions of the intermediate portion between curvature changes have very slight positive curvature or very slight negative curvature compared to the curvatures of the forward and aft portions so that, overall, the intermediate portion is generally flat or curve-less, wherein the intermediate portion extends to within twenty-five percent of the chord length starting from the trailing edge, and wherein the aft portion extends to the trailing edge, such that the aft portion has positive curvature from the intermediate portion to the trailing edge.

12. The turbine stage of claim 11 wherein the forward and aft portions change a sign of the second derivative of a curve defining the suction side.

13. The turbine stage of claim 12 wherein the aft inflection point is located within ten percent of the chord length starting from the trailing edge.

14. The turbine stage of claim 11 and further comprising a one or more rows of cooling holes extending along the radially extending body in a region of the suction side aft of the series of local curvature changes.

15. The turbine stage of claim 11 wherein the radially extending body comprises a vane or a blade.

16. The turbine stage of claim 11 , wherein the generally flat portion has a series of local curvature changes such that regions of the generally flat portion between curvature changes have very slight positive curvature or very slight negative curvature compared to the forward portion and the aft portion.

Assignees

• Aggarwala Andrew S
• Allen Bradley Eunice
• Grover Eric A
• Trindade Ricardo
• United Technologies Corp

Inventors

• Aggarwala Andrew S
• Allen-Bradley Eunice
• Grover Eric A
• Trindade Ricardo

Classifications

• F05D2240/124

  related to the suction side of a stator vane · CPC title

• F01D5/145

  Means for influencing boundary layers or secondary circulations (for compressors F04D29/68) · CPC title

• F01D5/148

  Blades with variable camber, e.g. by ejection of fluid · CPC title

• F05D2250/713

  inflexed · CPC title

• F01D5/141 Primary

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