Rotor blade tip clearance control device and method

摘要

Rotor blade tip clearance control device (40) adapted to control the clearance of a rotating aerofoil structure (46) with a surrounding casing portion (42) and method. The device comprises: a member (28) operatively connected to the casing portion (42); the member having at least a first configuration in which the casing portion is at a first radial position and a second configuration in which the casing portion is at a second radial position, wherein the configuration of the member is controlled by magnetic flux in a magnetic circuit which includes at least one ferromagnetic element comprising ferromagnetic material, whereby the configuration of the member is responsive to the temperature of the ferromagnetic element.