Nonlinear Vibration Analysis of Steam Turbine Rotating Wheel Equipped with the LSB48 Blades

10.6567/IFToMM.14TH.WC.OS4.007

Josef Voldřich；Jan Lazar；Pavel Polach

Bladed disk ； Contact stiffness ； Cyclic symmetry ； Friction contact ； Natural frequency ； Nonlinear vibration

Proceedings of the 14th IFToMM World Congress

14th-2（2015 / 10 / 27）

48 - 55

英文

Currently, long blades of rotating wheels of steam turbines' low-pressure stages comprise integral structural contact elements. The contact elements reinforce the bladed disk, which leads to re-tuning its natural frequencies. But they also act as friction dampers in the case of higher vibrations caused by undesirable excitation sources. The development of the long steam turbine blades is closely related to the computer modelling of the above-mentioned vibrations. In this work, two cases of excitation of nonlinear vibrations of the bladed disk equipped with the LSB48 blades are investigated: (i) travelling-wave excitation with two nodal diameters and (ii) the excitation by earthquake forces in horizontal direction of the rotation axis. The cyclic symmetry properties of the bladed disk are used for the calculations. Contact areas between blades are modelled using coupling elements implementing dry Coulomb friction. Finally, the accuracy of the mathematical model and the concept of the contact stiffness are discussed.