7. Critical speed analysis
To calculate the critical speeds of the turbogenerator, it was assumed that its plain bearing could be
approximated to a rigid bearing and that the shaft extension through the ball bearings could be ignored.
Two concentrated masses, representing the turbine and the rotor, positioned at specific points on a
weightless shaft are shown in Fig 10. The critical speeds of this arrangement were calculated by
considering the static deflection in the shaft produced by the two masses.
Deflection was calculated from the shaft’s flexibility influence coefficient