BUCKET DOVETAIL BRIDGE MEMBER AND METHOD FOR ELIMINATING THERMAL BOWING OF STEAM TURBINE ROTORS

摘要

A steam turbine has a rotor mounting axially spaced rotor wheels having male dovetails for mounting a plurality of axially spaced buckets having female dovetails. A plurality of arcuate bridging members extend axially between the axially adjacent bucket dovetails at locations spaced radially outwardly of the surface of the rotor shaft. A diaphragm in radial opposition to the bridging member mounts a brush seal having bristles engaging the bridging member. The bridging member carries backup labyrinth seal teeth for sealing with the diaphragm. The friction generated by contact between the brush seal bristles and bridging members lies radially outwardly of the rotor whereby non-uniform distribution of heat about the rotor surface due to frictional contact with the brush seal is avoided, with consequent avoidance of rotor bowing.