Abstract
In the past three decades, researches in rotor dynamics met with considerable success in modeling the structural dynamics of flexible rotors and in developing analysis techniques for the bearings supporting these rotors. As a result of these substantial technical advances, new high-performance turbomachinery was designed, developed, and put into service to operate at higher speed and higher energy density level. At the same time, instable rotor vibrations in compressors and turbines occurred more frequently and caused severe failures. The frequency leading to whirling instability is usually near one of the shaft critical speeds and can be caused by many factors, including hydrodynamic bearings, seals, internal damping, aerodynamic cross coupling, and torsional coupling. Instability due to fluid film forces and the internal damping of shafts often leads to self-excited vibration. This is introduced in this chapter in detail. The contents associated with rotor whirl are divided into six sections: the first emphasizes the construction of the mechanical model of the rotor in planar whirl; the second introduces the analytical expressions of the fluid-film forces of bearings and seals; the third treats the stability problem of planar whirl rotors with nonlinear and linear models; the fourth is devoted to establishing the analytical expressions of the internal force of rotation shafts; the fifth turns attention to instability caused by the internal damping of the rotor system; and the last discusses the cause and the prevention of the rotor whirl.
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Ding, W. (2010). Rotor Whirl. In: Self-Excited Vibration. Springer, Berlin, Heidelberg. https://doi.org/10.1007/978-3-540-69741-1_8
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DOI: https://doi.org/10.1007/978-3-540-69741-1_8
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