Principles and Applications of Hydrodynamic-Type Gas Bearings

Abstract

In this paper is described an experimental investigation of properties and some developments in the utilization of hydrodynamic-type gas-lubricated bearings, of both journal and thrust types, as distinct from hydrostatic bearings. Two specific developments are described, the one a pump for circulating carbon dioxide gas at 100 lb. per sq. in. gauge and 150 deg. C. through a loop in a nuclear reactor, the other a gas-bearing motor driving a pump for molten radioactive bismuth, the whole within a hermetically-sealed container. The simple machining requirements and special design principles are described. The performance of gas bearings may be predicted from normal liquid bearing theory if the loading is so small that the pressure rise within the bearing is a small fraction (for example, 10 percent) of the ambient pressure. For higher pressure ratios compressibility effects must be taken into account. The experimental results and techniques used are reported, those for plain journal bearings embracing a wide range of working conditions and absolute size including compressible flow operation. An explanation of the physical reasons for the change in performance in compressible flow bearings is given. The dynamic instability sometimes encountered in journal bearings and methods of avoiding it is also discussed.

A Review of Grooved Dynamic Gas Bearings

“…• Aerodynamic gas bearings (HDGB) [28,30,31] generate load capacity through the relative motion between the rotor and bearing sleeves. The viscous shear within the fluid film drags the lubricant into an aerodynamic wedge, which then generates a pressure gradient.…”

“…Muijderman [90,91] assessed the applicability of Whipple's incompressible NGT theory in depth combining the findings of other researchers, e.g., Ford, Boeker and Wordsworth et al [30,86,92]. In order to overcome the difficulties in matching Whipple's theory and the experiment conducted by Wordsworth [92], Muijderman modified Whipple's NGT method by considering grooves along a spiral curvature including end effects for thrust GBs.…”