Optimization of Groove Geometry for Thrust Air Bearing to Maximize Bearing Stiffness

Hydrodynamic gas film bearings are widely used for very high speed, lightly loaded rotating machinery. In the design of hydrodynamic gas film bearings, it is of cardinal importance to enhance the stiffness of gas films for minimizing the vibration due to external excitations. Among various types of hydrodynamic gas film thrust bearings, grooved bearings have an advantage of high stiffness and load carrying capacity, but the stiffness of the bearings strongly depends on groove geometry. Therefore, when the groove geometry is designed suitably, it is expected to improve considerably the stability characteristics of the bearings. However, the conventional bearing geometries are based on the fixed logarithmic spiral curve, and there is no literature treating how to change effectively the groove geometry to improve drastically the bearing characteristics. In this paper, the entirely new optimum design methodology, in which the groove geometry can be changed flexibly by using the spline function, is presented to maximize the stiffness of gas films for grooved thrust bearings, and the effectiveness of the methodology is verified experimentally.