Rotor damper

Patent metadata

Field	Value
Publication number	US-2016298459-A1
Application number	US-201615094393-A
Country	US
Kind code	A1
Filing date	Apr 8, 2016
Priority date	Apr 13, 2015
Publication date	Oct 13, 2016
Grant date	—

Abstract

A rotor stage of a gas turbine engine includes a platform from which rotor blades extend. The platform is provided with a circumferentially extending damper ring, the damper ring having an engagement surface that engages with a platform engagement surface of the platform. The platform engagement surface and the damper engagement surface can move relative to each other in the radial direction. In use, the damper engagement surface moves less in the radial direction than the platform engagement surface in response to diametral mode excitation. This causes friction between the two surfaces, thereby dissipating energy and damping the excitation. The platform engagement surface and the damper engagement surface engage over at least two separate engagement portions separated by a gap.

First claim

1 . A rotor stage for a gas turbine engine comprising:
a plurality of blades extending from a platform, the platform extending circumferentially about an axial direction; and a circumferentially extending damper element, wherein: the platform comprises a platform engagement surface; the damper element comprises a damper engagement surface; and the platform engagement surface engages the damper engagement surface over at least two separate engagement portions, the engagement portions being separated by a gap over which the platform engagement surface does not engage the damper engagement surface.

2 . A rotor stage according to claim 1 , wherein the engagement portions are circumferentially extending segments.

3 . A rotor stage according to claim 2 , wherein the engagement portions are annular segments.

4 . A rotor stage according to claim 1 , wherein the platform is ridged, thereby forming the at least two engagement portions separated by a gap.

5 . A rotor stage according to claim 4 , wherein the ridges protrude in a substantially axial direction.

6 . A rotor stage according to claim 4 , wherein the ridges protrude in a substantially radial direction.

7 . A rotor stage according to claim 1 , wherein the damper engagement surface is axisymmetric.

8 . A rotor stage according to claim 1 , wherein:
the damper engagement surface is an annular surface; and/or the damper element is an annular disc.

9 . A rotor stage according to claim 1 , wherein:
the damper engagement surface and the platform engagement surface are moveable relative to each other in a radial direction, the platform being more radially deformable than the damper element.

10 . A rotor stage according to claim 1 , comprising more than two engagement portions.

11 . A rotor stage according to claim 1 , further comprising a contact layer on one or both of the platform engagement surface and the damper engagement surface, wherein the contact layer is:
a low-friction layer that has lower friction than the underlying surface to which it is applied; and/or a hard layer that has increased hardness compared with the underlying surface to which it is applied.

12 . A rotor stage according to claim 1 , wherein the damper element and the platform are axially biased together, thereby providing an engagement load between the damper engagement surface and the platform engagement surface; and, optionally the rotor stage further comprising a biasing element that provides the axial bias by applying a force in the axial direction to the damper element to push the damper engagement surface onto the platform engagement surface.

13 . A rotor stage according to claim 1 , wherein the plurality of blades are formed integrally with the platform.

14 . A gas turbine engine comprising a rotor stage according to claim 1 .

15 . A method of damping vibrations in a rotor stage of a gas turbine engine, wherein:
the rotor stage is a rotor stage according to claim 1 ; the vibration comprises a travelling wave passing circumferentially around the circumferentially extending platform; and the damping is frictional damping generated through radial and/or circumferential slip between the platform engagement surface and the damper engagement surface.

Assignees

• Rolls Royce Plc

Inventors

• Bryant Michael F
• Edwards Garry M

Classifications

• F01D5/30

  Fixing blades to rotors; Blade roots {; Blade spacers} · CPC title

• F05D2220/32

  in gas turbines · CPC title

• F01D5/34

  Rotor-blade aggregates of unitary construction {, e.g. formed of sheet laminae; (discs formed of sheet laminae F01D5/028; ceramic materials F01D5/284, composite materials F01D5/282)} · CPC title

• F01D5/16

  for counteracting blade vibration · CPC title

• F05D2260/96

  Preventing, counteracting or reducing vibration or noise · CPC title