Blade tip clearance control apparatus using shroud segment position modulation

摘要

A clearance control apparatus has a pair of positioning mechanisms for quickly controlling the clearance between rotor blade tips and a shroud segment of a gas turbine engine casing. The positioning mechanisms are supported by axially-spaced casing bosses, coupled to the shroud segment via a shroud holder, and actuatable for moving radially between inner and outer stops. As the positioning mechanisms are moved between the inner and outer stops, the shroud segment is moved therewith toward and away from the rotor axis to respective inner and outer positions relative to the rotor at which corresponding desired minimum and maximum clearances are established between the shroud segment and rotor blade tips. A fluid cylinder on the casing has a piston coupled to the positioning mechanisms by a link. The cylinder is operable for actuating the positioning mechanisms to move solely to one or the other of the inner and outer stops and cause the shroud segment to move solely to one or the other of the inner and outer positions thereof to corresponding solely provide one or the other of the minimum and maximum clearances between the shroud segment and rotor blade tips.