In this paper, a dynamic model on a rigid rotor sliding bearing system with a SFD is established. The stability and bifurcation behaviors of the system are studied. On the basis of the differential equations of fluid...In this paper, a dynamic model on a rigid rotor sliding bearing system with a SFD is established. The stability and bifurcation behaviors of the system are studied. On the basis of the differential equations of fluid momentum and mass continuity, the distribution pressure function is derived by taking oil film inertia force into consideration. Damping force, clearance excitation force, interference force of different frequencies and static load are also considered in the model. Finally, the governing equations of the stability and bifurcation behaviors of the system are solved by Floquet theory. Simulation of dynamic model shows that the rigid rotor sliding bearing system can maintain stability and exhibit a Hopf bifurcation phenomenon in a certain range.展开更多
Many industrial applications and experiments have shown that sliding bearings often experience fluid film whip due to nonlinear fluid film forces which can cause rotor-stator rub-impact failures. The oil-film whips ha...Many industrial applications and experiments have shown that sliding bearings often experience fluid film whip due to nonlinear fluid film forces which can cause rotor-stator rub-impact failures. The oil-film whips have attracted many studies while the water-film whips in the water lubricated sliding bearing have been little researched with the mechanism still an open problem. The dynamic fluid film forces in a water sliding bearing are investigated numerically with rotational, whirling and squeezing motions of the journal using a nonlinear model to identify the relationships between the three motions. Rotor speed-up and slow-down experiments are then conducted with the rotor system supported by a water lubricated sliding bearing to induce the water-film whirl/whip and verify the relationship. The experimental results show that the vibrations of the journal alternated between increasing and decreasing rather than continuously increasing as the rotational speed increased to twice the first critical speed, which can be explained well by the nonlinear model. The radial growth rate of the whirl motion greatly affects the whirl frequency of the journal and is responsible for the frequency lock in the water-film whip. Further analysis shows that increasing the lubricating water flow rate changes the water-film whirl/whip characteristics, reduces the first critical speed, advances the time when significant water-film whirling motion occurs, and also increases the vibration amplitude at the bearing center which may lead to the rotor-stator rub-impact. The study gives the insight into the water-film whirl and whip in the water lubricated sliding bearing.展开更多
A dynamic model of a flexible rotor-sliding bearing system ( FRSBS ) with asqueeze film damper ( SFD) is established. Considered in the model are oil film inertia force,damping farce, clearance excitation force, inter...A dynamic model of a flexible rotor-sliding bearing system ( FRSBS ) with asqueeze film damper ( SFD) is established. Considered in the model are oil film inertia force,damping farce, clearance excitation force, interference force of different frequencies and staticload, as opposed to previous research. On the basis of this model, the optimal design of the systemis deeply studied. Simulation shows that the system optimization design can effectively improve thesystem stability.展开更多
文摘In this paper, a dynamic model on a rigid rotor sliding bearing system with a SFD is established. The stability and bifurcation behaviors of the system are studied. On the basis of the differential equations of fluid momentum and mass continuity, the distribution pressure function is derived by taking oil film inertia force into consideration. Damping force, clearance excitation force, interference force of different frequencies and static load are also considered in the model. Finally, the governing equations of the stability and bifurcation behaviors of the system are solved by Floquet theory. Simulation of dynamic model shows that the rigid rotor sliding bearing system can maintain stability and exhibit a Hopf bifurcation phenomenon in a certain range.
基金Supported by Specialized Research Fund for the Doctoral Program of Higher Education of China(Grant No.20120002110011)State Key Laboratory of Hydroscience and Engineering(Grant No.2014-KY-05)+1 种基金Tsinghua Scholarship for Overseas Graduate Studies,China(Grant No.2013128)Special Funds for Marine Renewable Engergy Projects(Grant No.GHME2012GC02)
文摘Many industrial applications and experiments have shown that sliding bearings often experience fluid film whip due to nonlinear fluid film forces which can cause rotor-stator rub-impact failures. The oil-film whips have attracted many studies while the water-film whips in the water lubricated sliding bearing have been little researched with the mechanism still an open problem. The dynamic fluid film forces in a water sliding bearing are investigated numerically with rotational, whirling and squeezing motions of the journal using a nonlinear model to identify the relationships between the three motions. Rotor speed-up and slow-down experiments are then conducted with the rotor system supported by a water lubricated sliding bearing to induce the water-film whirl/whip and verify the relationship. The experimental results show that the vibrations of the journal alternated between increasing and decreasing rather than continuously increasing as the rotational speed increased to twice the first critical speed, which can be explained well by the nonlinear model. The radial growth rate of the whirl motion greatly affects the whirl frequency of the journal and is responsible for the frequency lock in the water-film whip. Further analysis shows that increasing the lubricating water flow rate changes the water-film whirl/whip characteristics, reduces the first critical speed, advances the time when significant water-film whirling motion occurs, and also increases the vibration amplitude at the bearing center which may lead to the rotor-stator rub-impact. The study gives the insight into the water-film whirl and whip in the water lubricated sliding bearing.
文摘A dynamic model of a flexible rotor-sliding bearing system ( FRSBS ) with asqueeze film damper ( SFD) is established. Considered in the model are oil film inertia force,damping farce, clearance excitation force, interference force of different frequencies and staticload, as opposed to previous research. On the basis of this model, the optimal design of the systemis deeply studied. Simulation shows that the system optimization design can effectively improve thesystem stability.
