Aktive Regelung des Spitzenspiels in Turbomaschinen

A turbomachine (10) including a case (12), a rotor (44), a plurality of rotor blades (56,58) on the rotor (44), each having a blade tip (60), a shroud (16) around the rotor blade tips (60), and bearing means (64,66) mounting the rotor (44) on the case (12) for rotation about a centreline (22) of the case (12) and for bodily-shiftable movement in the direction of the centreline (22). The rotor blade tips (60) and an inside wall (32) of the shroud (16) flare radially outwards in the direction of the centreline (22) so that, when the rotor (44) moves in the direction of the centreline (22) towards the shroud (16), a clearance gap (62) between the blade tips (60) and the inner wall (32) of the shroud (16) decreases and vice versa. An electromagnetic actuator (100) on the case (12) magnetically attracts a thrust plate (94) on the rotor (44) against a net dynamic force produced on the rotor (44) during the operation of the turbomachine (10). A control system (118) of the actuator (100) controls the magnetic attraction of the actuator (100) in response to signals from a position sensor (116) measuring the actual magnitude of the clearance gap (62), so as to maintain the actual clearance gap (62) at a predetermined magnitude.