# US 9,429,027 B2 · Turbine airfoil tip shelf and squealer pocket cooling

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- Number: US 9,429,027 B2
- Document ID: US9429027B2
- Status: Granted
- Kind: B2
- Application number: 14/748,666
- Filed: 2015-06-24
- Published: 2015-10-15
- Granted: 2016-08-30
- Earliest claimed: 2012-04-05
- Assignees: United Technologies Corporation
- Applicants: United Technologies Corporation
- Inventors: Dominic J. Mongillo, Jr.; Steven Bruce Gautschi; San Quach
- Web page: https://patentgrep.com/patent/US9429027B2

## CPC

- F01D 5/20: Specially-shaped blade tips to seal space between tips and stator {(F01D5/225 takes precedence)}
- F05D 2260/202: by film cooling
- Y02T 50/60: Efficient propulsion technologies, e.g. for aircraft
- F01D: NON-POSITIVE DISPLACEMENT MACHINES OR ENGINES, e.g. STEAM TURBINES (machines or engines for liquids F03; non-positive displacement pumps F04D)
- F05D: INDEXING SCHEME FOR ASPECTS RELATING TO NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES, GAS-TURBINES OR JET-PROPULSION PLANTS
- Y02T: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION

## Abstract

An airfoil includes a pressure surface and a suction surface extending from a root section of the airfoil to a tip section of the airfoil. The airfoil also includes a leading edge and a trailing edge defining a chord length of the airfoil therebetween. The airfoil further includes a tip shelf formed along the tip section of the airfoil between the pressure surface and a tip shelf wall. The tip shelf wall is spaced between the pressure surface and the suction surface and 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.

## Claims

### Claim 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; and
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; wherein the tip shelf extends around the leading edge and onto the suction surface to terminate on the suction surface between the leading edge and the trailing edge of the airfoil; wherein the leading edge further comprises an indentation formed on the leading edge, the indentation extending along the leading edge between the root section of the airfoil and the tip section of the airfoil, and wherein the indentation intersects the tip shelf at the leading edge; wherein the tip shelf extends to the trailing edge of the airfoil to terminate at a downstream intersection of the pressure and suction surfaces such that the tip shelf communicates with both the pressure surface and the suction surface proximate to the trailing edge.

### Claim 2 (depends on 1)

The airfoil of claim 1, wherein the airfoil further comprises:
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.

### Claim 3 (depends on 1)

The airfoil of claim 1, further comprising a plurality of cooling holes formed in the indentation formed on the leading edge of the airfoil.

### Claim 4 (depends on 3)

The airfoil of claim 3, wherein at least one of the plurality of cooling holes formed in the indentation extends partially in a radial direction.

### Claim 5 (depends on 3)

The airfoil of claim 3, wherein at least one of the plurality of cooling holes formed in the indentation includes a transition opening that tapers inward into the leading edge of the airfoil.

### Claim 6 (depends on 1)

The airfoil of claim 1, further comprising a plurality of cooling holes formed in the tip shelf proximate the pressure surface of the airfoil.

### Claim 7 (depends on 6)

The airfoil of claim 6, wherein the plurality of cooling holes are arranged in at least two rows on the tip shelf for a first portion of the chord length and the plurality of cooling holes are arranged in a single row for a second portion of the chord length.

### Claim 8 (depends on 1)

The airfoil of claim 1, further comprising a plurality of cooling holes formed in the tip shelf proximate the leading edge of the airfoil.

### Claim 9 (depends on 8)

The airfoil of claim 8, wherein at least one of the plurality of cooling holes formed in the tip shelf proximate the leading edge of the airfoil includes a transition opening that tapers inward into the tip shelf.

### Claim 10 (depends on 8)

The airfoil of claim 8, wherein at least one of the plurality of cooling holes formed in the tip shelf proximate the leading edge of the airfoil includes an oval cross-sectional profile.

### Claim 11 (depends on 8)

The airfoil of claim 8, wherein at least one of the plurality of cooling holes formed in the tip shelf extends at least partially in a radial direction.

### Claim 12

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; and
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; 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, the open perimeter recess and the tip shelf terminating on the convex surface proximate the leading edge.

### Claim 13 (depends on 12)

The blade of claim 12, further comprising:
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.

### Claim 14 (depends on 12)

The blade of claim 12, further comprising a plurality of cooling holes formed in the tip shelf at the leading edge and proximate to the concave surface.

### Claim 15 (depends on 14)

The blade of claim 14, wherein each of the plurality of cooling holes formed in the tip shelf includes a transition opening that tapers inward into the tip shelf.

### Claim 16 (depends on 12)

The blade of claim 12, wherein the tip shelf comprises a step disposed between 55% and 25% of the chord length measured from the trailing edge of the airfoil, wherein the step shifts a portion of the tip shelf generally radially outward toward the tip section.