Prediction of Static Characteristics of Hydrodynamic Air Foil Bearing Considering Contact and Friction Between Foils

The elastohydrodynamic model of hydrodynamic air foil bearing has been built to study the influence of rotor speed, the friction coefficient between bearing components, load and other parameters on the foil displacement of hydrodynamic air bearing under steady-state conditions. The static characteristics of hydrodynamic air foil bearing are predicted by using the numerical simulation method. The results show that the radial displacement of the foil is the smallest at both ends of the bearing and the largest at the middle of the bearing, while the top foil changes gently along the width of the bearing away from the maximum pressure. After increasing the rotating speed, the maximum fluid pressure improves and the action position shifts, and the increase of rotating speed has a significant impact on the maximum pressure. Improving the friction coefficient µ₂ between the bump foil and the bearing sleeve has different effects on the displacement of the foil. When µ₁ is 0.1, by promoting µ₂, the transverse displacement of the top foil at the pressure peak increases by 20.9%, the longitudinal displacement is reduced by 8.9%, and the transverse displacement and the maximum longitudinal negative displacement of the bump foil are decreased by 53.2% and 31.7%, respectively. Furthermore, the longitudinal displacement of bump foil at the fixed end has been reduced by increasing the load, and the relative size of the friction coefficient between the components affects the size and direction of the foil displacement at the same load.