Performance comparative analysis of hydrostatic bearings lubricated with low-viscosity cryogenic fluids

The lubricant for the hydrostatic bearings in an operating cryogenic turbopump is generally liquid hydrogen or liquid oxygen. However, in experiments, these are typically replaced by water or liquid nitrogen for economical and safety reasons. In this study, the static performance characteristics of an orifice-compensated hydrostatic bearing in these four lubrication-fluid cases are calculated and compared by numerically solving the turbulent Reynolds equation. The effects of the fluid viscosity and density on the bearing performance are discussed. A combined parameter of viscosity and density is introduced to describe the effect of the fluid properties on bearing performance. Ultimately, four improved bearings based on the original bearing are proposed, one each for the four fluids, to achieve better performance.