Blade-to-blade vibration damper

• US 4,936,749 A
• Filed: 12/21/1988
• Issued: 06/26/1990
• Est. Priority Date: 12/21/1988
• Status: Expired due to Term

• Current Assignee: General Electric Company
• Original Assignee: General Electric Company
• Inventors: Arrao, Anthony S., Nourse, John G.
• Primary Examiner(s): Powell, Jr., Everette A.
• Application Number:
  US07/287,232
• Time in Patent Office: 552 Days
• Field of Search: 416/190, 416/191, 416/193 A, 416/500
• US Class Current: 416/193.00A
• CPC Class Codes: F01D 11/008 by spacer elements between the blades, e.g. independent interblade platforms
• CPC Class Codes: F01D 5/22 Blade-to-blade connections, e.g. for damping vibrations
• CPC Class Codes: Y10S 416/50 Vibration damping features

Abstract

A blade-to-blade vibration damper for a turbine rotor blade is disclosed. Each blade has airfoil, platform and root portions. A plurality of blades are circumferentially spaced about a rotor disk. An inclined recess extends into the platform portion of each blade from a first surface thereof, and toward its root portion. A U-shaped wire-form damping member has its in-turned marginal end portions slidably received in each recess. When the rotor disk is rotated at a sufficient angular speed, the damping members move outwardly by the centrifugal force acting thereon to engage the opposing surface of the platform portion of the adjacent blade. When so engaged, the members damp vibrations of such blades and seal the space between the opposing platform surfaces.

Claims

1. An improved rotor blade adapted to be mounted on a rotor disk in circumferentially spaced relation to an adjacent blade, said improved blade comprising:

an airfoil portion, a platform portion and a root portion, said platform portion having a first surface adapted to be arrange din spaced facing relation to an opposing surface of said adjacent rotor blade, said improved blade also having an arcuate surface extending between said root portion and said first surface, said arcuate surface being bowed outwardly in a transverse direction;

two transversely spaced inclined recess slots extending into said platform portion from said first surface and toward said root portion; and

a U-shaped member having a rod-like central portion and in-turned marginal end portions, said marginal end portions being arranged in said slots for sliding movement relative thereto so that said central portion may move toward and away from said bowed arcuate surface along the path defined by said slots, said U-shaped member being adapted to be moved relative to said platform portion to a position at which no portion thereof will extend outwardly beyond said first surface toward said opposing surface, said member being so configured and arranged that when said rotor is caused to rotate at a sufficient angular speed, the centrifugal force acting on said member will urge said member to move outwardly along said path so that said central portion will engage said adjacent blade opposing surface to damp vibrations of at least one of said blades.

2. The improved rotor blade as set forth in claim 1 wherein said U-shaped member is size relative to said arcuate surface so that upon attempted insertion of said U-shaped member backwards into said slots, said end portions would protrude outwardly beyond said first surface toward said opposing surface.

3. The improved rotor blade as set forth in claim 1 wherein said member is formed of a length of wire.

4. The improved rotor blade as set forth in claim 2 wherein the diameter of said central portion is greater than the spacing between said improved blade first surface and said adjacent blade opposing surface.

5. The improved rotor blade as set forth in claim 2 wherein said central portion has an effective length substantially equal to an overlapped length of said improved blade first surface and said adjacent blade opposing surface.

6. The improved rotor blade as set forth in claim 1 wherein the axis of said recess is inclined at an acute included angle of about 26°

with respect to a longitudinal axis of said blade.

7. The improved rotor blade as set forth in claim 1 wherein said recess has an outer wall, and wherein said member engages said outer wall substantially in line contact when said rotor is caused to rotate at or greater than said sufficient angular speed.

8. The improved rotor blade as set forth in claim 1 wherein said member engages said adjacent blade opposing surface substantially in line contact when said rotor disk is caused to rotate at or greater than said sufficient angular speed.

9. The improved rotor blade as set forth in claim 1 wherein said member is adapted to substantially seal the space between said improved blade first surface and said adjacent blade opposing surface when said rotor disk is caused to rotate at said sufficient angular speed.

10. The improved rotor blade as set forth in claim 1 wherein said improved blade first surface is a leading surface of said platform portion.

11. The improved rotor blade as set forth in claim 1 wherein said rotor disk has an axis, and wherein each of said improved blade first surface and said adjacent blade opposing surface is arranged in a substantially radial plane.

12. An improved rotor blade adapted to be mounted on a rotor disk in circumferentially spaced relation to an adjacent blade, said improved blade comprising:

an airfoil portion, a platform portion and a root portion, said platform portion having a first surface adapted to be arrange din spaced facing relation to an opposing surface of said adjacent rotor blade, said blade also having an arcuate surface extending between said root portion and said first surface, said arcuate surface being bowed in a transverse direction;

two transversely spaced inclined recess slots extending into said platform portion from said first surface and toward said root portion; and

said slots being configured for receiving the marginal end portions of a U-shaped member for sliding movement relative thereto, said slots being configured so that the portion of said member between said end portions may move toward and away from said arcuate bowed surface, said U-shaped member being adapted to be moved relative to said platform portion to a position at which no portion thereof extends outwardly beyond said first surface toward said opposing surface, said member being so configured and arranged that when said rotor is caused to rotate at a sufficient angular speed, the centrifugal force acting on said member will urge said member to move outwardly along a path defined by said slots to engage said adjacent blade opposing surface to damp vibrations of at least one of said blades.

13. A rotor assembly, comprising:

a rotor disk adapted to be rotated about an axis;

a plurality of blades mounted don said disk in circumferentially spaced relation for rotation therewith, each of said blades having an airfoil portion, a platform portion and a root portion, the platform portion of at least one of said blades having a first surface arranged in spaced facing relation to an opposing surface of an adjacent blade, each of said blades having said first surface also having an arcuate surface extending between said root portion and said first surface, said arcuate surface being bowed in a transverse direction;

two transversely spaced inclined recess slots extending into said platform portion of each associated blade from said first surface thereof and extending toward said root portion thereof; and

a U-shaped damping member having a rod-like central portion and in-turned marginal end portions, said end portions being movably mounted in said slots so that said central portion may move toward and away from said bowed arcuate surface along the path defined by said slots, said U-shaped portion being adapted to be moved relative to said platform portion to a position at which no portion thereof extends outwardly beyond said first surface toward said opposing surface, said damping member and slots being cooperatively configured and arranged with respect to said adjacent blade opposing surface so that when said assembly is rotated at a sufficient angular speed, said damping member will move outwardly along said path so that said central portion will engage said adjacent blade opposing surface to damp vibrations of at least one of said blades.

14. The rotor assembly as set forth in claim 13 wherein said damping member is operatively arranged to seal the space between said one blade first surface and said adjacent blade opposing surface when said rotor disk is rotated at said sufficient angular speed.

15. The rotor assembly as set forth in claim 13 wherein said damping member is U-shaped and has its in-turned marginal end portions facing into said recess.

16. The rotor assembly as set forth in claim 15 wherein said damping member has a rod-like portion intermediate said in-turned marginal end portions, which intermediate portion is adapted to engage said adjacent blade opposing surface when said rotor disk is rotated at said sufficient angular speed.

17. The rotor assembly as set forth in claim 15 wherein said U-shaped damping member is formed of a length of wire.

18. The rotor assembly as set forth in claim 17 wherein the diameter of said wire is greater than the spacing between said one blade first surface and said adjacent blade opposing surface.

19. The rotor assembly as set forth in claim 13 wherein the length of said rod-like central portion is substantially equal to an overlapped length of said one blade first surface and said adjacent blade opposing surface.

20. The rotor assembly as set forth in claim 13 wherein said first surface is a leading surface of said one blade platform portion and said opposing surface is a trailing surface of said adjacent blade platform portion.