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). In use, the damper engagement surface (210) and the platform engagement surface (110) move relative to each other in a radial direction, in response to diametral mode excitation. This causes friction between the two surfaces, thereby dissipating energy and damping the excitation. The rotor stage (100) is arranged such that the engagement load between the damper engagement surface (210) and the platform engagement surface (110) is a function of the rotational speed of the rotor stage (100).