Abstract
This paper studies the chaotic and nonlinear dynamic behaviors of a rigid rotor supported by externally pressurized double air films (EPDAF) bearing system. A hybrid numerical method combining the differential transformation method and the finite difference method is used to calculate pressure distribution of EPDAF bearing system and bifurcation phenomenon of rotor center orbits. The results obtained for the orbits of the rotor center are in good agreement with those obtained using the traditional finite difference approach. The results presented summarize the changes which take place in the dynamic behavior of the EPDAF bearing system as the rotor mass and bearing number are increased and therefore provide a useful guideline for the bearing system.
Highlights
Air bearing systems are characterized by low noise under rotation and by their low frictional losses
It can be seen that the finite difference method (FDM) suffers numerical instability at specific values of the rotor mass and time step and the hybrid method converges under all the considered conditions and represents a more appropriate method for analyzing the dynamic response of the externally pressurized double air films (EPDAF) bearing system
This hybrid method might be not the best candidate, from Table 1 the results obtained by the FDM and hybrid method for the orbits of the rotor center prove that a good agreement exists between different sets of results
Summary
Air bearing systems are characterized by low noise under rotation and by their low frictional losses. The results show that the bearing number and rotor mass are the major parameters for bifurcation phenomenon and the rotor behaviors including periodic and nonperiodic motions at different operational situations. In 2010, Wang [10] analyzed the bifurcation behavior and nonlinear dynamics of rigid rotor supported by microgas journal bearings and showed that the rotors exhibited a complex dynamic behavior comprising periodic, subharmonic, and quasiperiodic responses at different values of the rotor mass and bearing number, respectively. The present study analyzes the nonlinear dynamic response of a rigid rotor supported by two externally pressurized double air films bearings. To analyze the EPDAF bearing system, the motions of the rotor center are governed by Reynolds’ equations and solved by using a hybrid method combining the differential transformation method (DTM) and the finite difference method. The proposed method is applied to analyze the bifurcation phenomenon and dynamic response of the rotor for rotor mass and bearing number in the ranges 1.0∼12.0 kg and 1.0∼12.0, respectively
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