Thermal effect induced by viscous dissipation on characteristics of aerodynamic foil journal bearing with aero-thermo-elastic coupling

Abstract

In aero–thermo–elastic analysis, aerodynamic foil bearings are one of the most representative components that involve strong coupling among microscale shear flow, aerodynamic heating, and elastic foil deformation. Researches on the role of aerodynamic heating in bearings are really inadequate. This study clarifies the effect of thermal behavior induced by viscous dissipation on the characteristic of an aerodynamic foil journal bearing (AFJB) with a rotational speed of 4 × 104–8.0 × 104r/min and an eccentricity ratio of 0.4–0.8. The results indicate that the thermal effect induced by viscous dissipation significantly affects the aerodynamics of shear flow and the dynamic response of elastic foils in the AFJB. The inherent thermal effect induced by viscous dissipation strengthens the inherent viscosity-temperature effect and weakens the pulsation of static pressure while intensifying the temperature increase of the shear flow. The dynamic response of the elastic foils in the solid domain is closely associated with the behavior of shear flow in the fluid domain. The static pressure and temperature elevation increase with the rotational speed and eccentricity ratio owing to strengthened hydrodynamic effects. The effect of thermal behavior induced by viscous dissipation on the aerodynamic and thermal characteristics of the shear flow becomes significant at high rotational speeds and eccentricity ratios. The load capacity and peak temperature elevation increase with the rotational speed and eccentricity ratio. In the solid domain, the thermal effect induced by viscous dissipation negligibly affects the deformation of the elastic foils because the variation in the temperature increase is insignificant, thus resulting in insignificant variations in the properties of the gas film. This study elucidates the impact of aerodynamic heating, especially the thermal effect induced by viscous dissipation, on the aero–thermo–elastic field in bearings and the performance of the bearings. The results of this study serve as basic design guidelines for AFJBs and can be used to optimize the operation security.