Load characteristics and dynamic stability of hydrogen aerostatic gas bearings in turbo-expanders

Hydrogen-lubricated bearings are critical components of hydrogen turbo-expanders in large-scale hydrogen liquefaction systems. However, the low viscosity of hydrogen presents significant challenges to the bearing’s operational stability, and research on this topic remains limited. Therefore, we investigate the static characteristics of a hydrogen aerostatic gas bearing (HAGB) using a 3D computational fluid dynamics (CFD) model, comparing its performance with that of helium and air bearings. Our analysis reveals that the HAGB primarily operates under the influence of the hydrostatic effect, with its hydrodynamic effect being relatively weak due to hydrogen’s low viscosity. Moreover, the impact of the HAGB’s operational and structural parameters on its dynamic behavior is investigated. The dynamic stability is evaluated using the dissipated energy and the equivalent damping coefficient. The results indicate that the equivalent damping coefficient can be enhanced by increasing the rotational speed and supply pressure, as well as reducing the gas film clearance. Specifically, in the investigated configuration, the HAGB demonstrates optimal vibration damping when the inlet orifice diameter is 0.2 mm.