Author(s):
Moreira, Miguel 
; Antunes, J. ; Pina, H.
Date: 2000
Origin: Repositório Comum
Subject(s): Rotor; Eigenvalue; Linear models
Document details
An Improved Linear Model for Rotors Subject to Dissipative Annular Flows
Description
In a previous paper, Antunes, Axisa and co-workers developed a linearized model for the dynamic of rotors under moderate fluid confinement, based on classical perturbation analysis covering two different cases: (i) dissipative motions of a centered rotor; (ii) motions of an eccentric rotor for a frictionless flow. Following the same procedures and assumptions, we derive here an improved model to cover the more general case of a dissipative linearized motion of an eccentric rotor. Besides the natural position variables, a new flow variable, which can be physically interpreted as the fluctuating term of average tangential velocity, was introduced, yielding an additional eigenvalue in the linear analysis. The new variable introduced, coupled with the rotor motions, is unavoidable when frictional effects are not neglected and yield a richer modal behavior which can be related with delay effects of the flow responses to the abovementioned rotor motions. Because system dynamics are strongly dependent on actual rotor eccentricity, the validity of this model (or other linear model) is dependent on an adequate estimation of this parameter.
In a previous paper, Antunes, Axisa and co-workers developed a linearized model for the dynamic of rotors under moderate fluid confinement, based on classical perturbation analysis covering two different cases: (i) dissipative motions of a centered rotor; (ii) motions of an eccentric rotor for a frictionless flow. Following the same procedures and assumptions, we derive here an improved model to cover the more general case of a dissipative linearized motion of an eccentric rotor. Besides the natural position variables, a new flow variable, which can be physically interpreted as the fluctuating term of average tangential velocity, was introduced, yielding an additional eigenvalue in the linear analysis. The new variable introduced, coupled with the rotor motions, is unavoidable when frictional effects are not neglected and yield a richer modal behavior which can be related with delay effects of the flow responses to the abovementioned rotor motions. Because system dynamics are strongly dependent on actual rotor eccentricity, the validity of this model (or other linear model) is dependent on an adequate estimation of this parameter.
Document Type
Conference Object
Language English
Language English
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