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|Type:||Artigo de periódico|
|Title:||Non-linear Analysis Of Hydrodynamical Bearings In A Vertical Shaft [análise Não-linear De Mancais Hidrpdinâmicos Montados Em Um Rotor Vertical]|
|Abstract:||In a running rotor, bearings are of fundamental importance in defining its dynamic behaviour. Physically, the oil film viscous flow caused by the relative motion between the shaft and the bearing internal part builds up a pressure distribution on the rotor surface, yielding to non-linear hydrodynamic forces which are position and fluid condition dependent, in journal bearings. The knowledge of these forces is of fundamental importance in the analysis of the vibratory motion in mechanical equipments. This work consists in the presentation and the application of non-linear mathematical models that can represent hydrodynamic forces exerted by the oil film in bearings, which support a vertical flexible shaft in rotating machines. These non-linear forces are analytically evaluated based on the rotor shaft orbital position in the hydrodynamical bearings. These hydrodynamic forces, as well as those resulted from any eccentric unbalance, are the external excitation sources included in the system equation of motion. A particular characteristic of this method is the easy determination of the non-linear forces through an indirect solution for the pressure distribution integration. The dynamical behaviour of the system, due to external unbalancing forces, is analised by means of the orbits, graphically plotted for some interesting running conditions. From the numerical analysis presented, the oil film whip phenomena as well as a limit cycle in cylindrical bearings for the orbits at different rotational speeds can be observed. Strong non-linearities can be observed in the tilling-pad bearings due to its variable geometry, analysing the tilt angle of the pads. The tilting-pad bearing high stability can be noticed by the rotor frequency response and its orbit amplitudes in this type of bearings.|
|Appears in Collections:||Unicamp - Artigos e Outros Documentos|
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