Abstract
Nonsynchronous rotating damping, i.e. energy dissipations occurring in elements rotating at a speed different from the spin speed of a rotor, can have substantial effects on the dynamic behaviour and above all on the stability of rotating systems.The free whirling and unbalance response for systems with nonsynchronous damping are studied using Jeffcott rotor model. The system parameters affecting stability are identified and the threshold of instability is computed. A general model for a multi‐degrees of freedom model for a general isotropic machine is then presented. The possibility of synthesizing nonsynchronous rotating and nonrotating damping using rotor‐ and stator‐fixed active dampers is then discussed for the general case of rotors with many degrees of freedom.
Highlights
The oil film is assumed to rotate at half the spin speed, with the result of giving way to an
Force Fr rotates at the spin speed (Fr meCO2 if it is due to the eccentricity e of. the centre of mass) and Fn is fixed in the inertial frame, possibly being time-dependent
Icol counter-rotating damping with >co’r/d, while for counter-rotating damping with a speed lower than the mentioned value and for co-rotating damping the condition for stability is expressed by Eq (7)
Summary
Dipartimento di Meccanica, Politecnico di Torino, C.so Duca degli Abruzzi, 24-1 10129 Torino, Italy (Received 29 January 1999," Revised 15 May 1999; In final form 31 May 1999). Nonsynchronous rotating damping, i.e. energy dissipations occurring in elements rotating at a speed different from the spin speed of a rotor, can have substantial effects on the dynamic behaviour and above all on the stability of rotating systems. The free whirling and unbalance response for systems with nonsynchronous damping are studied using Jeffcott rotor model. The system parameters affecting stability are identified and the threshold of instability is computed. A general model for a multi-degrees of freedom model for a general isotropic machine is presented. The possibility of synthesizing nonsynchronous rotating and nonrotating damping using rotor- and stator-fixed active dampers is discussed for the general case of rotors with many degrees of freedom
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