Patent attributes
A rotor stage (100) of a gas turbine engine (10) comprises a platform (120) from which rotor blades extend. The platform is provided with a circumferentially extending damper ring (200), the damper ring having an engagement surface (210) that engages with a platform engagement surface (110) of the platform (120). The platform engagement surface (110) and the damper engagement surface (210) can move relative to each other in the radial direction. In use, the damper engagement surface (210) moves less in the radial direction than the platform engagement surface (110) in response to diametral mode excitation. This causes friction between the two surfaces, thereby dissipating energy and damping the excitation.