Determination of A Dynamic Model For A Centrifugal Steam Turbine: Characteristics Analysis and Operating Point Calculation

Turbines manipulate fluid flows, they play an important role in energy conversions as a work exchanger between the fluid and a mechanical component whose moving part consists of a rotor fitted with fins. The study of the response of the rotors to the unbalances can appear a trivial field, the determination of the modal dampings according to the standards remains notably insufficient. This work has proposed a multimodal analysis path constituting a serious improvement of these standards. This method applies for outage forecasts. Two particular aspects of modeling have been treated to improve the prediction of natural frequencies. The first concerns the assembly with a strong tightening of the couplings on the ends of the shafts, and the second concerns the stepped shafts with large changes in diameter, which required the development of a finite element of torsion at two degrees of freedom per node of a conical section. The adaptation of the machine during its changes of production regime was easily explained. The established model is also used to demonstrate the instability near the operating point-of the operating characteristic-and also to study the dynamic behavior.