Establishment of thermo-elastic-fluid coupling model of with considering structural thermal expansion and lubricating performances study of air foil thrust bearing

This paper investigates air foil thrust bearings of circumferentially distributed bumps, employing non-isothermal Reynolds equation and 3D energy equation to describe the pressure distribution, thickness distribution, and temperature distribution of the air film, respectively. A 3D thermo-elastic-fluid coupling model of AFTBs is established using elasticity theory and the finite element method. This model comprehensively accounts for thermal expansion of the foil structures and thrust disc, centrifugal deformation of the rotor-thrust disc, heat transfer between bearing structures, and thermal resistance of the air gap in the contact areas. The reliability of the theoretical model is verified by comparing numerical results with experimental results. Furthermore, the results predicted in this paper are consistent with those obtained from existing THD models in the literature. The results indicate that the TEHD model is more precise than THD model when the initial clearance decreases and rotational speed increases. On this basis, a specific example is studied and obtains the air film pressure, air film thickness, air film temperature distributions, and deformation and temperature distribution of structures considering structural thermal expansion. The two TEHD models that considers structural thermal expansion and ignores structural thermal expansion are compared by analyzing the effects of rotational speed and load on the lubricating performances of the bearing. Finally, the influences of foils structural parameters on the load capacity and the maximum temperature of all structures are also investigated to provide practical engineering reference value for bearing design.