Flow dam design for labyrinth seals to promote rotor stability

摘要

A method and apparatus for reducing steam swirl in a steam turbine. A plurality of seal segments ( 14 ) are circumferentially juxtaposed to form a seal ring ( 12 ) encircling the turbine shaft ( 10 ), each seal segment ( 14 ) supporting a plurality of circumferentially disposed annular seal fins ( 20 ) to limit axial steam flow along the shaft ( 10 ). A plurality of flow dams ( 40 ) are disposed within grooves ( 42 ) defined in the plurality of seal fins ( 20 ) and seal segments ( 14 ) for limiting circumferential steam flow and thereby reducing rotor instability.