Computational evaluation of dynamic coefficients of thrust bearings; effect of artificial texturing on thermohydrodynamic performance
Résumé
Fluid film thrust bearings are commonly used in industry, providing durable and reliable operation at
high values of load carrying capacity, accompanied by low friction losses. A major advantage of
hydrodynamic fluid film bearings, over other types of bearings, is their enhanced dynamic behaviour,
especially under transient or impact loads. Currently, a systematic approach to identify the dynamic
coefficients of thrust bearing geometrical configurations utilising high complexity CFD simulation
data has not yet been established. It is therefore imperative to develop a method, capable of evaluating
the dynamic characteristics of complex bearing designs and allow the evaluation of bearing response
under transient loads. In the present work, a computational approach is proposed to estimate the
stiffness and damping coefficients of fluid-film thrust bearings. A CFD-based ThermoHydroDynamic
(THD) numerical model of the bearing is developed and utilised for performing an initial steady-state
simulation at given rotational speed and thrust load, as well as subsequent transient simulations at
increasing or decreasing thrust loads. The former simulation is used to calculate the stiffness
coefficient of the bearing at the specified conditions, while the latter are appropriately post-processed
to estimate the damping coefficient of the bearing at different values of rotor acceleration. The
procedure is repeated at different operating conditions, yielding a map of the dynamic coefficients of
the bearing. Finally, a single degree of freedom model is generated, which utilises the calculated values
of dynamic coefficients to evaluate transient bearing performance under any given thrust load history.
The proposed methodology is applied to compare the dynamic response characteristics of a
conventional sector-pad tapered-land thrust bearing and a textured tapered-land thrust bearing of the
same principal dimensions.
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Georgios Koutsoumpas_Surface Topography_Metrology and Properties, IOP Publishing 2020, 8 (2).pdf (921.14 Ko)
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