Effects of Rotor Centrifugal Expansion on the Static and Dynamic Characteristics of Porous Gas Journal Bearing

As the rotational speed increases, the centrifugal expansion of the rotor will significantly affect the performance of the porous gas bearing. However, this rotor’s centrifugal effect has not been studied thoroughly. In this paper, the rotor centrifugal expansion is simplified as a two-dimensional plane stress problem. The gas flow in the porous bushing and the gas film is governed by Darcy’s law and the modified Reynolds equation, respectively. The perturbation method and the finite difference method are adopted to calculate the bearing load and dynamic coefficients for a high-speed porous gas bearing. Comparisons between the simulated results and the available experimental and theoretical data are carried out to validate the proposed model. On this basis, the influence of rotor centrifugal expansion on the performance and the operational conditions of the high-speed porous gas bearing is studied systematically. The results indicate that rotor centrifugal expansion greatly improves the bearing load and dynamic coefficients of the high-speed porous gas bearing with a large rotor diameter and small bearing clearance, but reduces the allowable eccentricity ratio and titling angle.