Effects of Local Preload on the Performance of Tilting Pad Bearings

To study the effects of local preload on the performance of tilting pad bearings, a model was established for the bearing based on thermo-elasto-hydrodynamic lubrication theory, which was applied to the analysis of a five-pad tilting-pad bearing for a high-speed gas turbine. Results show that the stiffness and damping of a tilting pad bearing increase with the rise of local preload, which are affected by the location of pad pivots in different directions. For the pads in the direction with changing local preload, their maximum babbit temperature and pad pressure increase with rising local preload, while the minimum thickness of oil film decreases, and the influence on these pads would be greater than those in other directions. If local preload rises, the static equilibrium position would move away from the pad, which will move towards the pad if the local preload decreases. The lubrication oil flow reduces with rising local preload, resulting in increased power loss of the bearing.