The flow factors for the average Reynolds equation introduced by Patir and Cheng (1978, 1979) are extended to be valid for thin film gas lubrication. The effects of molecular mean free-path on the roughness-induced flow factors are included on the assumption that the local compressibility is small. The derivation of flow factors is carried out by means of the perturbation approach developed by Tripp (1983). The results are expressed in terms of Knudsen number, Peklenik parameter and nondimensional film thickness defined as the ratio of average film thickness and standard deviation of composite roughness. Two-dimensional roughness effects on the load-carrying capacity of a gas lubricated finite slider are also investigated.

No abstract

No abstract

No abstract

This paper describes the performance characteristics of two types of journal bearings, tilting-pad and offset halves, operating under high-speed conditions where the journal peripheral speed is in excess of 100 m/s. Experimental investigations into bearing eccentricity, temperatures and dynamic coefficients were carried out with a specially designed test rig. These results are compared with theoretical data which are obtained from thermohydrodynamic lubrication theory. The agreement is satisfactory. However, further improvements are necessary to predict more accurate thermal performance of the unloaded pads.