Computational fluid dynamics (CFD) applied to model hybrid-lubricated bearings

Abstract

Consulta en la Biblioteca ETSI Industriales (9223)

[EN] The active tilting-pad journal bearing (ATPJB) emerge as a solution for the instability problems at high rotor angular velocities in other lubricated bearings, such as the tilting pad bearing (TPJB). In order to accurately design ATPJB the pressure distribution in the pads needs to be calculated, since the properties of the bearing (stiffness and damping) depend on it, but in order to implement the Reynolds equation with the effects of the pressure injection new assumptions needs to be done. This can be done by means of the Modified Reynolds equation, which assumptions have much to do with the boundary conditions in the injection area. The aim of this thesis is to give qualitative results of the fluid flow in laminar regime in order to better understand the flow mechanism in the ATPJB and check the correctness of the results coming from the Modified Reynolds equation. In order to do that a CFD model has been developed and the results are analyzed either in an isothermal 2D model or a thermal 3D model. The results are divided in two groups: 1) Hydrostatic dominant flow: The results from the Modified Reynolds equation match with CFD. 2) Hydrodynamic dominant flow: The discrepancies between CFD and the Modified Reynolds equation increase as the Rayleigh step flow seen in the edges of the feed line starts to play a role in the lubrication. A tuned parameter to incorporate the Rayleigh step effect in the feed line for the Modified Reynolds equation is presented.