FRICTION DAMPER

• US 20170342840A1
• Filed: 05/27/2016
• Published: 11/30/2017
• Est. Priority Date: 05/27/2016
• Status: Active Grant

• Current Assignee: Pratt & Whitney Canada Corporation (Raytheon Technologies Corporation d/b/a RTX)
• Original Assignee: Pratt & Whitney Canada Corporation (Raytheon Technologies Corporation d/b/a RTX)
• Inventors: PANKRATOV, Maksim
• Granted Patent: US 10,450,865 B2
• Time in Patent Office: Days
• CPC Class Codes: F01D 5/10 Anti- vibration means specially adapted for radial flow machines or engines F01D5/04
• CPC Class Codes: F05D 2220/323 for aircraft propulsion, e.g. jet engines
• CPC Class Codes: F05D 2240/20 Rotors
• CPC Class Codes: F05D 2250/184 sinusoidal
• CPC Class Codes: F05D 2260/96 Preventing, counteracting or reducing vibration or noise
• CPC Class Codes: F16F 15/129 characterised by friction-damping means F16F15/1202, F16F15/1238 , F16F15/131 take precedence
• CPC Class Codes: F16F 7/06 in a direction perpendicular or inclined to the axis of rotation F16F7/023 takes precedence

Abstract

A damper ring is mounted in frictional engagement with a radially inwardly facing surface of a circumferential groove defined in a rotary part of a gas turbine engine. Energy dissipation is provided via sliding friction of the ring in the groove. Pressure relief dimples are provided around the outer diameter of the ring for locally reducing contact pressure at the outer diameter below a value at which the damper ring locks in the groove by friction forces when subject to centrifugal loads.

Claims

1. A damper ring mountable in a groove defined on a circumferentially inner surface of a rotor of a gas turbine engine to provide a friction damper assembly, the damper ring comprising:

an outer circumferential surface configured to be centrifugally loaded against a radially inwardly facing surface of the groove, a plurality of circumferentially spaced-apart pressure relief dimples defined in the outer circumferential surface of the damper ring, the pressure relief dimples being configured to locally reduce the contact pressure at the outer circumferential surface of the damper ring below a threshold value at which friction forces lock the damper ring against movement in a circumferential direction relative to the rotor.

2. The damper ring defined in claim 1, wherein the pressure relief dimples have a depth less than a length in the circumferential direction of the pressure relief dimples.

3. The damper ring defined in claim 1, wherein the pressure relief dimples provide the outer circumferential surface of the damper ring with a generally sinusoidal profile in the circumferential direction.

4. The damper ring defined in claim 1, wherein the pressure relief dimples include pressure relief dimples of different shapes around the circumference of the damper ring.

5. The damper ring defined in claim 1, wherein the pressure relief dimples form a regular pattern around the circumference of the damper ring.

6. The damper ring defined in claim 1, wherein the pressure relief dimples form an irregular pattern around the circumference of the damper ring.

7. The damper ring defined in claim 1, wherein the damper ring includes several rings with different pressure relief dimple shapes.

8. A gas turbine engine rotor mounted for rotation about an axis, the rotor comprising:

a body defining a circumferential groove having a radially inwardly facing surface, at least one damper ring mounted in the circumferential groove, the at least one damper ring having a plurality of pressure relief dimples formed at spaced intervals in an outer circumferential surface thereof and leaving circumferentially extending lands therebetween, in use, the at least one damper ring being displaceable under a centrifugal load from a first position, in which the lands are in contact with the radially inwardly facing surface of the circumferential groove while the pressure relief dimples are spaced radially inwardly therefrom, to a second position, in which the pressure relief dimples are deformed under the centrifugal load in contact with the radially inwardly facing surface of the circumferential groove.

9. The gas turbine engine rotor defined in claim 8, wherein in the second position, a contact pressure between the deformed pressure relief dimples and the radially inwardly facing surface of the circumferential groove is less than the pressure required to lock the at least one damper ring by friction in the circumferential groove.

10. The gas turbine engine rotor defined in claim 9, wherein in the second position, the contact pressure between the lands and the radially inwardly facing surface of the circumferential groove is greater than the contact pressure between the deformed pressure relief dimples and the radially inwardly facing surface.

11. The gas turbine engine rotor defined in claim 9, wherein the pressure relief dimples have a shallow profile, a depth of the pressure relief dimples being less than a length thereof in the circumferential direction.

12. The gas turbine engine rotor defined in claim 9, wherein the outer circumferential surface of the at least one damper ring has a sinusoidal profile in the circumferential direction.

13. The gas turbine engine rotor defined in claim 9, wherein the pressure relief dimples include pressure relief dimples of different shapes around the circumference of the at least one damper ring.

14. The gas turbine engine rotor defined in claim 9, wherein the pressure relief dimples form a regular pattern around the circumference of the at least one damper ring.

15. The gas turbine engine rotor defined in claim 9, wherein the pressure relief dimples form an irregular pattern around the circumference of the at least one damper ring.

16. The gas turbine engine rotor defined in claim 9, wherein the at least one damper ring includes several damper rings with different pressure relief dimple shapes.

17. A method of providing frictional damping for a rotor of a gas turbine engine, the rotor having a circumferential groove with a radially inwardly facing surface, the method comprising:

providing at least one damper ring configured to be centrifugally loaded against the radially inwardly facing surface of the circumferential groove of the rotor when the rotor is rotatably driven; and

adjusting a contact pressure between an outer circumferential surface of the at least one damper ring and the radially inwardly facing surface of the groove below a threshold value at which the at least one damper ring locks against movement in a circumferential direction relative to the rotor when subject to centrifugal loads of a magnitude corresponding to centrifugal loads encountered during normal engine operation, wherein adjusting comprises providing pressure relief dimples at circumferential intervals in at least one of the radially inwardly facing surface of the circumferential groove and the outer circumferential surface of the at least one damper ring.

18. The method of claim 17, wherein adjusting comprises conducting a contact analysis on a numerical model of a computer simulation of the at least one damper installed in the circumferential groove of the rotor and subjected to said centrifugal loads, and determining the threshold value of the contact pressure at which the friction between the at least one damper ring and the radially inwardly facing surface of the groove causes the at least one damper ring to be locked against movement in the circumferential direction.

19. The method of claim 18, wherein adjusting further comprises optimizing the shape of the pressure relief dimples so that the contact pressure at each of the pressure relief dimples be locally inferior to the threshold value.

20. The method of claim 19, wherein optimizing the shape of the pressure relief dimples comprises considering the internal tensile or compressive force acting on the at least one damper ring from each side of a given point on the outer circumference surface of the at least one ring as well as the friction force at this given point of contact with the circumferential groove.