TURBINE AIRFOIL TIP SHELF AND SQUEALER POCKET COOLING

• US 20150118063A1
• Filed: 04/10/2014
• Published: 04/30/2015
• Est. Priority Date: 04/05/2012
• Status: Active Grant

• Current Assignee: Rtx Corporation
• Original Assignee: United Technologies Corporation (Rtx Corporation)
• Inventors: Lewis, Scott D., Mongillo, Dominic J. Jr., Gautschi, Steven Bruce, Corcoran, Christopher
• Granted Patent: US 9,284,845 B2
• Time in Patent Office: Days
• US Class Current: 416/97.R
• CPC Class Codes: F01D 5/186 Film cooling F01D5/187 takes precedence
• CPC Class Codes: F01D 5/20 Specially-shaped blade tips to seal space between tips and stator F01D5/225 takes precedence
• CPC Class Codes: F05D 2260/202 by film cooling
• CPC Class Codes: Y02T 50/60 Efficient propulsion technologies, e.g. for aircraft

Abstract

An airfoil comprises pressure and suction surfaces extending from a root section to a tip section of the airfoil. The airfoil also comprises a leading edge and trailing edge defining a chord length therebetween. A tip shelf is formed along the tip section between the pressure surface and a tip shelf wall, the tip shelf wall being spaced between the pressure surface and the suction surface. A squealer pocket is formed along the tip section between the tip shelf wall and a squealer tip wall extending from the suction surface. The tip shelf extends from within 10% of the cord length measured from the leading edge to within 10% of the chord length measured from the trailing edge. The squealer pocket extends from within 10% of the chord length measured from the leading edge to terminate less than 85% of the chord length measured from the trailing edge.

Claims

1. An airfoil comprising:

a pressure surface and a suction surface extending from a root section of the airfoil to a tip section of the airfoil;

a leading edge and a trailing edge defining a chord length of the airfoil therebetween;

a tip shelf formed along the tip section of the airfoil between the pressure surface and a tip shelf wall, wherein the tip shelf wall is spaced between the pressure surface and the suction surface, wherein the tip shelf extends from within 10% of the chord length measured from the leading edge to within 10% of the chord length measured from the trailing edge; and

a squealer pocket formed along the tip section of the airfoil between the tip shelf wall and a squealer tip wall extending from the suction surface, wherein the squealer pocket extends from within 10% of the chord length measured from the leading edge to terminate less than 85% of the chord length measured from the trailing edge.

2. The airfoil of claim 1, wherein the squealer pocket extends from within 10% of the chord length measured from the leading edge to terminate between 25% and 80% of the chord length measured from the trailing edge.

3. The airfoil of claim 1, wherein the squealer pocket extends from within 10% of the chord length measured from the leading edge to terminate between 45% and 60% of the chord length measured from the trailing edge.

4. The airfoil of claim 1, wherein the squealer pocket extends for more than 15% of the chord length and less than 75% of the chord length.

5. The airfoil of claim 1, wherein the tip shelf extends for more than 90% of the chord length.

6. The airfoil of claim 1, wherein the squealer pocket extends from a location within 5% of the chord length measured from the leading edge of the airfoil to a location within 50% of the chord length measured from the trailing edge of the airfoil.

7. The airfoil of claim 1, wherein the tip shelf extends around the leading edge and onto the suction surface.

8. A gas turbine engine blade comprising:

an airfoil comprising convex and concave surfaces extending from a root section to a tip section and from a leading edge to a trailing edge, the leading and trailing edges defining a chord length therebetween;

a tip shelf defining an open perimeter recess between the concave surface and a tip shelf wall, wherein the tip shelf wall is spaced between the convex surface and the concave surface, wherein the open perimeter recess extends from a region within 5% of the chord length measured from the leading edge of the airfoil to a region within 5% of the chord length measured from the trailing edge of the airfoil; and

a squealer pocket defining a closed perimeter recess between the tip shelf wall and a squealer tip wall extending congruently from the convex surface, wherein the closed perimeter recess extends from a region within 5% of the chord length measured from the leading edge of the airfoil to terminate in a region between 25% and 80% of the chord length measured from the trailing edge of the airfoil.

9. The blade of claim 8, wherein the open perimeter recess defined by the tip shelf extends along the concave surface of the airfoil for more than 95% of the chord length.

10. The blade of claim 9, wherein the closed perimeter recess defined by the squealer pocket extends along the tip section of the airfoil for more than 20% of the chord length and less than 75% of the chord length.

11. The blade of claim 10, wherein the open perimeter recess defined by the tip shelf extends along the concave surface of the airfoil from a region within 2% of the chord length measured from the leading edge of the airfoil to a region within 2% of the chord length measured from the trailing edge of the airfoil.

12. The blade of claim 11, wherein the open perimeter recess defined by the tip shelf extends from an intersection of the convex and concave surfaces at the trailing edge and around the leading edge of the airfoil onto the convex surface.

13. The blade of claim 8, further comprising a plurality of cooling holes formed in the tip shelf to maintain a pocket of cooling fluid along the tip section of the airfoil between the tip shelf wall and the concave surface.

14. The blade of claim 13, wherein each of the plurality of cooling holes formed in the tip shelf includes a transition opening that tapers inward into the tip shelf to diffuse the cooling fluid as it exits the plurality of cooling holes formed in the tip shelf.

15. The blade of claim 13, further comprising a plurality of cooling holes formed in the squealer pocket to maintain a pocket of cooling fluid along the tip section of the airfoil between the tip shelf wall and the squealer tip wall.

16. An airfoil for a gas turbine engine, the airfoil comprising:

pressure and suction surfaces extending from a root section to a tip section;

leading and trailing edges defining a chord length therebetween;

a squealer tip cavity extending along the tip section of the airfoil, the squealer tip cavity defined between a squealer tip wall extending congruently from the suction surface and a tip shelf wall extending between the squealer tip wall and the pressure surface, wherein the squealer tip cavity extends from a location within 10% of the chord length measured from the leading edge of the airfoil and terminates at a location less than 85% of the chord length measured from the trailing edge; and

a tip shelf recess formed between the tip shelf wall and the pressure surface of the airfoil, the tip shelf recess extending from a location within 5% of the chord length measured from the leading edge of the airfoil to a location within 5% of the chord length measured from the trailing edge of the airfoil.

17. The airfoil of claim 16, wherein the tip shelf recess extends from a location within 2% of the chord length measured from the leading edge of the airfoil to a location within 2% of the chord length measured from the trailing edge.

18. The airfoil of claim 16, further comprising a squealer discharge flow channel extending from the squealer tip cavity to the trailing edge of the airfoil.

19. The gas turbine engine of claim 18, wherein the tip shelf extends to the trailing edge of the airfoil to terminate at a downstream intersection of the pressure and suction surfaces.

20. The gas turbine engine of claim 19, wherein cooling fluid flow from the tip shelf and squealer pocket merge at the discharge flow channel.