Abstract
Gas bearing is a mechanical element using gas as a lubricant, it has high rotational accuracy and low friction. However, gas bearing has a fault of small load capacity. If this bearing overcome it, practical range of this bearing will more spread. In this study, deal with gas bearing it made notches ―to improve bearing performance― at the rotor in the bearing. With this bearing structure, when internal force acts on the bearing surface opposite another one with notches, it is expected this bearing can obtain greater load capacity from the asymmetry of the bearing surface. On the other hand, stability and dynamic performance of the rotor and the gas bearing system are still unclear. In this study, dynamic characteristics of this bearing was calculated from analysis using perturbation method, and evaluated rotor stability using these. As a result, notches caused the diagonal term component of the equation of motion of the rotor to decrease, and these made the rotor unstable on the analysis. Further, as another analysis approach, we used non-linear orbit method to judge validity. As a result, both results were different. As one of the causes, it is considered that each is a linear, nonlinear method. Also, from the result of non-linear orbit method, it turned out that rotor orbit showed different aspects depending on conditions of notch size and rotation speed.
