Abstract
A modified Reynolds equation for flow dynamically represented as incompressible is used to model the dynamics of a thin film bearing with slip flow and a rapidly rotating coned rotor. Previous studies including a Navier slip length shear condition on the bearing faces are extended to investigate applications with a coned bearing gap. A modified Reynolds equation for the film flow is coupled, through the pressure exerted by the fluid film, to the dynamic motion of the stator. Introducing a new variable leads to explicit analytical expressions for the pressure field and force on the stator with the equation for the time-dependent face clearance transformed to a nonlinear second-order non-autonomous ordinary differential equation. The face clearance for periodic axial motion of the coned rotor is obtained using a stroboscopic map solver; a focus is investigating bearing behaviour under extreme conditions. The coupled fluid flow and unsteady bearing dynamics are examined for a range of configurations to evaluate potential face contact over a range of bearing surface conditions.
Highlights
Thrust bearing technology typically utilises a thin fluid film to maintain a face clearance between the rotor and stator, when subjected to external axial loads through generating changes in local film pressure from the differential motion of the rotating and stationary elements.K
Typical bearing geometries include a journal bearing with a supporting cylindrical sleeve containing a rotating cylindrical shaft separated by a thin air film, as studied by Belforte et al [1]; a slider bearing comprising two non-parallel moving plates separated by a thin lubricating air film, as considered by Witelski [2]; and a thrust bearing which has an important significance dynamically in turbomachinery applications operating with very high rotational speeds
This work identifies for a more general case, where a slip flow is relevant, that contact may occur, and for more practical purposes, maintaining a minimum gap thickness will depend on the coning angle, slip length, amplitude of rotor oscillations disturbance amplitude and direction of pressurisation
Summary
Thrust bearing technology typically utilises a thin fluid film to maintain a face clearance between the rotor and stator, when subjected to external axial loads through generating changes in local film pressure from the differential motion of the rotating and stationary elements. Considering similar geometry with incompressible flow and incorporating a coned rotor, Bailey et al [8] provided more extensive analytical investigations and examined the effect of prescribed axial oscillations with amplitude larger than the equilibrium film thickness. A Reynolds equation with slip was derived, and the bearing dynamics were investigated for rotor displacement of small amplitude in comparison to the film thickness, using existing perturbation analysis with results given for the no-slip and slip conditions. This study extends the formulation, analysis and predictions of the previous study of Bailey et al [8] in which a coned thrust bearing is considered within a classical no-slip condition which predicts that face contact will not occur, a period of very close proximity may exist. To verify the numerical solution in the limit of small face clearance asymptotic analysis is carried out, and two different symbolic computations were used to verify the correctness of the lengthy algebra
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
