Hydrostatic Bearings for Cryogenic Rocket Engine Turbopumps

This paper summarizes an analytic and experimental investigation of hydrostatic bearings for use in high-pressure cryogenic rocket engine turbopumps. A hydrostatic bearing analysis was developed to predict bearing steady-state and time-dependent (stability) performance. The analysis accounts for the effects of turbulence, inertia, and compressibility in the fluid film. Bearing design charts were generated from the analysis to permit rapid prediction of bearing performance and to aid in the selection of optimum bearing configuration. Liquid hydrogen and liquid oxygen turbopump conceptual designs were prepared and the designs were used to establish hydrostatic bearing size and performance requirements. The turbopump designs included provision for operation when bearing supply pressure is insufficient to support the rotor. Two bearing designs, one LH2 and one LO2, were fabricated and tested in a test rig. Test bearing designs met turbopump requirements and included the turbopump start-stop rotor support provision. Experimental data for both test programs agreed well with steady-state predictions and the bearings were stable under all conditions. Both test bearing designs were in excellent mechanical condition after testing, which included 10 simulated turbopump start-stop cycles.