Diagnostic Damage Control of Shaft Trains in Turbine Units According to Torsional Vibration Parameters

An analysis of existing methods for determining the natural frequencies of torsional vibrations of the shaft trains in power turbine units is carried out in order to assess the potential for using changes in natural frequencies to diagnose shaft damage. A computational modeling of torsional vibrations of a shaft train having a circumferential crack allowed informative natural frequencies to be determined for the purposes of detecting damages and the locations of natural frequency measurements to be established to a satisfactory degree of accuracy. An assessment of changes in natural frequencies from depth and characteristic locations of a circumferential crack is carried out. An alternative method for detecting violations of the shaft train integrity, based on monitoring changes in the angles of static twisting, is also considered.