Rotor dynamics

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The rotor dynamics combines the fields of solid state dynamics of rotors , the dynamics of the flow processes in the lubrication gap of plain bearings and, when using active magnetic bearings, the dynamics of mechatronic systems.

The rotor dynamics describes, among other things:

  • The amplitude increases in the relative shaft vibration when the rotor bearing systems run up and run down. As a result of the rotational frequency (1X) imbalance excitation , resonances are passed through at so-called critical speeds .
  • Resonance states when a rotor is excited by several speed harmonics. Is z. If, for example, a rotor is excited at a rotational frequency (1X) by the unbalance and by a one-sided shaft crack with twice the rotational frequency (2X), there is resonance even at half the value of each critical speed. The rotor blades of axial turbo machines and disk-shaped components of steam turbine rotors (shield vibrations) can be excited in resonance by much higher speed harmonics.
  • Raising of the rotor natural frequencies through the gyroscopic effect of disc-shaped components of rotors and radial impellers. Change of the rotor natural frequencies and natural vibration forms with the speed due to the speed dependence of the rigidity of the plain bearings .
  • The occurrence of subsynchronous components of the shaft oscillation when the stability limit is reached and exceeded , at which the unbalanced (i.e. rotational frequency) shaft oscillation becomes unstable.

Rotor dynamics took off as a technical science with the development and production of steam turbines at the end of the 19th century. Problems of rotor dynamics were not only to be solved in the development of thermal and hydraulic turbo-machines. B. also in the development of centrifuges , high-speed spindles of spinning machines, with air-bearing spindles of drills in dental technology, as well as in the past decades in the development of hard disk drives .

literature

  • Robert Gasch , Rainer Nordmann, Herbert Pfützner: Rotordynamik , Springer Verlag, 2nd edition, 2007.
  • Aurel Stodola: steam and gas turbines. With an appendix on the prospects for heat engines and gas turbines. Springer Verlag, 6th edition, 1925.