Method of and device for avoiding rotor instability to enhance dynamic power limit of turbines and compressors

Claim 1

In a turbine driven by a fluid medium, wherein the turbine includes: a rotor having blades projecting therefrom, the blades being surrounded by an annular shroud; a stator surrounding but in spaced relation to the shroud to define an annular space between the stator and the shroud, and a labyrinth seal disposed in the annular space, the labyrinth seal including a plurality of axially spaced, annular plates extending radially from the stator toward the shroud, the improvement characterized by: a plurality of baffle plates mounted on the stator positioned in spaced relation to one another in the annular space between the shroud and stator, each baffle extending both radially and axially within the space and having an inward radial extent in the annular space slightly less than the radial extent of the seal plates whereby differentials in fluid pressure around the annular space are reduced resulting in reduction of self-excited oscillations of the rotor and thereby allowing an increase in the power imparted to the blades of the turbine.