Abstract: The axial and radial clearances of turbine-generator units are quite small. Therefore collision and friction will happen in the case of diminishing axial or radial clearances between the rotating and the stationary parts, which will cause unit vibrations. In this paper, the mechanism, occasion and location of the vibration caused by collision and friction are introduced. Through the analysis on the causes and characteristics of the axial and radial collision and friction, the methods for identifying the vibration under different conditions are presented. Finally, measures to prevent the vibration in the manufacturing, installation, maintenance, startup and running of the units are put forward.

Key words: steam turbine generator, collision and friction between rotating and stationary parts, frictional vibration