# Patent

## Title
Turbine blade with mate face cooling air flow

## Abstract

A gas turbine engine blade comprises a dovetail, a shank extending from the dovetail, an airfoil, and a platform between the shank and the airfoil. The platform comprises a side wall extending between an upstream side and a downstream side of the platform. A first pin channel extends from the upstream side of the sidewall and a second pin channel, co-axial with the first pin channel, extends from the downstream side of the sidewall. The first channel includes a radial notch at the upstream longitudinal end of the first pin channel.

## Background
CROSS REFERENCE TO RELATED APPLICATIONS
This application contains subject matter related to application Ser. No. 13/048,618, filed even date herewith and entitled “Damper Pin”, and hereby incorporated by reference.
BACKGROUND OF THE INVENTION
1. Technical Field
The present invention relates to the field of turbine blades of gas turbine engines, and in particular to a turbine blade that cooperates with a damper pin and an adjacent turbine blade to provide cooling air flow to the mate face of the adjacent blades.
2. Background Information
Turbine blades generally include an airfoil, a platform, a shank and a dovetail that engages a rotor disk. An axially extending damper pin couples adjacent turbine blades along their platform. To provide cooling air flow between the mate face of the adjacent blades, a scallop cut may be provided in the platform rail.
There is a need for improved cooling along the mate face of adjacent turbine blades.
SUMMARY OF THE INVENTION
According to an aspect of the invention, a gas turbine engine blade comprises a dovetail, a shank extending from the dovetail, an airfoil, and a platform between the shank and the airfoil, the platform comprising a side wall extending between an upstream side and a downstream side of the platform, wherein a first pin channel extends from the upstream side of the sidewall and a second pin channel, co-axial with the first channel, extends from the downstream side of the sidewall, where the first channel includes a radial notch at the upstream longitudinal end of the first pin channel
According to another aspect of the invention, a gas turbine engine blade assemblage comprises a dovetail, a shank extending from the dovetail, an airfoil, a platform and a pin, where platform includes a side wall extending between an upstream side and a downstream side of the platform; a first pin channel extends from the upstream side of the sidewall; a second pin channel, co-axial with the first pin channel, extends from the downstream side of the sidewall; the first channel includes a radial notch at the upstream longitudinal end of the first pin channel, and the pin is disposed within the first and second pin channels and includes a radial projection that seats within the notch.
The notch may include a straight surface substantially parallel to the first and second pin channels, and an arcuate surface. The notch may also include a sidewall substantially perpendicular to the first and second damper channels.
The foregoing features and the operation of the invention will become more apparent in light of the following description and the accompanying drawings.



BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a pictorial illustration of adjacent turbine blades coupled by a damper pin;
FIG. 2 is an exploded view of the damper pin coupling the adjacent turbine blades;
FIG. 3 is a perspective view of the platform region of a turbine blade;
FIG. 4 is a perspective view of the platform region with the damper pin in its registered operable position on the platform region of the turbine blade of FIG. 3;
FIGS. 5A-5C illustrate a first embodiment of the damper pin in various axially rotated views;
FIG. 6 is an exploded perspective view of the platform in the area of a notch that seats a projection on the pin;
FIGS. 7A-7C illustrate a second embodiment of the damper pin in various axially rotated views;
FIGS. 8A-8C illustrate a third embodiment of the damper pin in various axially rotated views; and
FIG. 9 is a perspective view of the platform region of the turbine blade with the damper pin of FIGS. 8A-8C in its registered operable position on the platform region of the turbine blade.



DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a pictorial illustration of adjacent gas turbine blades 10, 12 coupled by a damper pin 14. Each of the blades 10, 12 extends radially outward from a rotor disk (not shown), and includes an airfoil 16, 18, a platform 20, 22, a shank 24, 26, and a dovetail 28, 30, respectively. The airfoil, platform, shank, and dovetail are collectively known as a bucket.
FIG. 2 is an exploded view of the pin 14 coupling the adjacent turbine blades 10, 12. FIG. 3 is a perspective view of the platform region 22 of the turbine blade 12. The airfoil 18 includes a convex suction side 32 and an opposite concave pressure side (not shown), and a leading edge 34 and a trailing edge 36.
The platform 22 separates the airfoil 18 and the shank 26, and includes an upstream side 38 and a downstream side 40 that are connected together with a suction-side edge 42 and an opposite pressure-side edge (not shown).
The shank 26 includes a substantially convex sidewall 44 and an opposite substantially concave sidewall (not shown) connected together at an upstream sidewall 46 and a downstream sidewall 48 of the shank 26. When coupled within the rotor disk, the substantially convex sidewall 44 of the blade 12 and the substantially concave sidewall of the blade 10 form a shank cavity 50 between the adjacent shanks 24, 26.
A platform undercut 52 is defined within the platform 22 for trailing edge cooling. A first channel 54 and a second channel 56 extend (e.g., axially) from the platform for receiving the damper pin 14 (FIGS. 1 and 2). The first channel 54 includes a first pedestal surface 58 on the upstream side, and the second channel 56 includes a second pedestal surface 60 on the downstream side. A notch 62 is located on the upstream side of the first pedestal surface 58.
FIG. 4 is a perspective view of the platform region of the turbine blade 12 with the pin 14 in its operable position within the first and second channels 54, 56. FIGS. 5A-5C illustrate a first embodiment of the pin 14 in various axially rotated views. Referring now to FIGS. 4 and 5A-5C, the damper pin includes a first flat longitudinal end region 64, a second flat longitudinal end region 66 and a reduced cross sectional area/undercut region 68. The reduced cross sectional area/undercut region 68 is separated from the first flat longitudinal end region 64 by a first main body region 70, and separated from the second flat longitudinal end region 66 by a second main body region 72. To allow cooling air to flow radially outward from the shank cavity 50 to the suction-side edge 42 of the platform, the cross section of the reduced cross sectional area/undercut region 68 is less than the cross sectional area of each of the first and second main body regions 70, 72. The cross sectional area/undercut region 68 is coaxial/concentric with respect to both the first and second main regions 70, 72, and the cooling air flows from the shank cavity 50 along opposite sides of the reduced cross sectional area/undercut region at the same axial position along the pin. The first and second flat longitudinal end regions may a semi-circular cross section.
To prevent position mistakes of the pin 14 within the channels 54, 56, the pin includes a projection 74 at the longitudinal end of the first flat longitudinal end region 64. The projection 74 seats in the notch 62 (see FIG. 4). The pin may be a metal alloy such as for example IN100, IN718, IN625 or INCONEL® X-750 alloys.
The depths and width of the reduced cross sectional area 68 of the pin are selected based upon the desired amount of cooling flow to the side edges of the platform (e.g., side edge 42 of the platform 22). For example, in the pin embodiment illustrated in FIGS. 4 and 5A-5C, the reduced cross sectional area may have a diameter of about 0.200 inches, while the first and second main body regions 70, 72 may have a diameter of about 0.310 inches. The length of the pin 14 is selected to run from about the upstream sidewall to about the downstream sidewall.
FIG. 6 illustrates an exploded perspective view of the notch 62. The notch is formed by a straight flat surface 68 and arcuate surface 69 that extends from the flat surface. The notch 62 is also formed by notch sidewall surfaces 71, 73. The surface 68 may be substantially parallel to the first and second pin channels 54, 56 (FIG. 3), while the sidewall surface 73 may be substantially perpendicular to the damper channels. The notch 62 may be formed by machining during manufacture of the bucket, or during overhaul or repair of the bucket.
FIGS. 7A-7C illustrate a second embodiment of a damper pin 70 in various axially rotated views. The pin 70 is substantially similar to the pin 14; the two differ primarily in that the undercut region which allows cooling air to pass is formed by a continuous helical cut/channel 80 along the surface of the pin within a helical undercut region 82. The helical undercut region 82 is separated from the first flat longitudinal end region 64 by the first cylindrical main body region 70, and from the second flat longitudinal end region 66 by the second cylindrical main body region 72. The helical cut allows cooling air to flows from the shank cavity 50 along opposite sides of the pin within the helical undercut region 82.
Rather than removing material from the surface of the pin to allow cooling air to radially pass from the shank cavity 50 to the side edges of the platform, one or more radial through holes may be formed within the pin. For example, FIGS. 8A-8C illustrate a damper pin 90 in various axially rotated views. The pin 90 is substantially similar to the pin 14 illustrated in FIGS. 5A-5C; the two differ primarily in that a longitudinal slit 92 radially extends through the pin, allowing cooling air to flow from the shank cavity 50 to the side edges (e.g., see side edge 42 illustrated FIG. 3). The slit 92 is separated from the first flat longitudinal end region 64 by the first main body region 70, and from the second flat longitudinal end region 66 by the second main body region 72. One of ordinary skill will immediately recognize that the slit may be replaced by a plurality of individual through holes in order to provide the desired cooling flow.
FIG. 9 is a perspective view of the platform region of the turbine blade with the damper pin of FIGS. 8A-8C in its operable position on the platform region of the turbine blade.
One of ordinary skill will also recognize that the first and second main body regions may take on shapes other then cylindrical. For example, it is contemplated these regions may be rounded surfaces such as ovals or other surfaces, for example having flat faces such as hexagon, diamond and square. The first and second main body regions may also take upon the shape of the adjacent platform surfaces to maintain effective air sealing.
Although this invention has been shown and described with respect to the detailed embodiments thereof, it will be understood by those skilled in the art that various changes in form and detail thereof may be made without departing from the spirit and scope of the claimed invention.

## Claims

1. A gas turbine engine blade assemblage, comprising:
a dovetail;
a shank extending from the dovetail;
an airfoil;
a platform between the shank and the airfoil, the platform comprising a sidewall extending between an upstream side and a downstream side of the platform, wherein a first pin channel extends from and through the upstream side of the sidewall, wherein a second pin channel extends from and through the downstream side of the sidewall, wherein the first and second pin channels are co-axial, and wherein the first pin channel includes a radial notch at an upstream longitudinal end of the first pin channel, and the second pin channel is at least partially formed by a second pedestal surface that is substantially planar and extends to and through the sidewall at the downstream side of the platform; and
a pin within the first and second pin channels, wherein the pin includes a radial projection that sits within the notch.

2. The assemblage of claim 1, wherein the notch comprises a straight surface substantially parallel to the first and second pin channels, and an arcuate surface.

3. The assemblage of claim 1, wherein the pin comprises:
a first longitudinal end region;
a second longitudinal end region;
a reduced cross sectional area region; and
wherein the reduced cross sectional area region is separated from the first longitudinal end region by a first main body region and the reduced cross sectional area region is separated from the second longitudinal end region by a second main body region, wherein a cross sectional area of the reduced cross sectional area region is less than a cross sectional area of each of the first and second main body regions, and wherein the reduced cross sectional area region is concentric with the first and second main body regions.

4. The assemblage of claim 3, wherein the radial projection extends from a longitudinal end of the first longitudinal end region.

5. The assemblage of claim 1, wherein the pin comprises:
a first longitudinal end region that sits within the first pin channel;
a second longitudinal end region that sits within the second pin channel;
a longitudinal slit radially extending through the pin; and
wherein the slit is separated from the first longitudinal end region by a first main body region and the slit is separated from the second longitudinal end region by a second main body region.

6. The assemblage of claim 5, wherein the radial projection extends from a longitudinal exterior of the first longitudinal end region.

7. The assemblage of claim 6, wherein the first and second main body regions are cylindrical.

8. The assemblage of claim 1, where the pin comprises:
a first longitudinal end region;
a second longitudinal end region;
an undercut region; and
wherein the undercut region is separated from the first longitudinal end region by a first main body region and the undercut region is separated from the second longitudinal end region by a second main body region, wherein the undercut region is undercut with respect to the first and second main body regions, and wherein the radial projection extends from a longitudinal end of the first longitudinal end region.

9. The assemblage of claim 8, wherein the pin is formed from a metal alloy selected from the group consisting of IN100, IN718, IN625, and INCONEL X-750.

10. The assemblage of claim 8, wherein the first and second main body regions are cylindrical.

11. The assemblage of claim 8, wherein the undercut region is formed by a continuous helical cut about a surface of the undercut region that allows cooling air to flow along opposite surfaces of the pin.