Modal parameters and turbo-generator torsional behavior

The authors present the modal theory of modeling a turbogenerator shaft and, from this, derive parameters that give a good indication of the shaft´s torsional behavior. These parameters are the torsional interaction susceptibility (TIS), which indicates the amount a mode is destabilized due to torsional interaction, and the mode torque susceptibility (MTS), which indicates the susceptibility of a shaft section to high torque from a particular mode. These parameters enable one to gauge the torsional performance of a turbogenerator without having to do detailed computer simulations. Calculated results demonstrate the ability of these parameters to enable comparisons of the torsional behavior of modes from different turbogenerators