Design and Stress Analysis of Extraterrestrial ... - The Black Vault

For the rotor diagram presented in
Fig. 3.80a,
3811
Ce = '(2 -102
-Similarly, for the rotor diagram in Fig. 3,80b
Cnp en .Canup
where
3, 8!-11 ; 1=eo
This diagram amounts to a rotor without special elastic elements
in the supports if the latter are not absc" _y rigid. Therefore,
when the elasticity of the supports is commensurate with the
elasticity of the rotor, the critical rpm must be determined with
support pliability taken into account, i.e., it is necessary to
examine the single "rotor-housing" elastic system.
Damping critical rotor modes
In the revolution o,' a turbine rotor various forces of resistance
act on it. They includa forces of friction in the, bearings, the
forces of friction between the rotor elements and t'.: medium in which
it is rotating, the forces of internal friction in rh-e shaft material,
etc. These forces create moment of resistance to rolation which is
overcome by the external torque but does not affect the amoun; of
shaft deflection although it prevents the precessive motion of the
shaft and iweduces its deflection.
These forces of resistance are used for damping the vibrations
if the resonance modes are in the working range or must be passed
through in the process of starting.
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