A Compact Electrically-Driven Booster Pump for Saturated LH2

NASA mission projections indicate a need for pumping up to 0.6 kg/s LH2 flow with 25-45 psid head rise. To meet these requirements, Creare has assessed the preliminary design of a low NPSH cryogenic LH2 pump. The pump is a single stage centrifugal pump using a shrouded impeller, and cavitation-resistant inlet inducer, nominally operating at 24,750 rpm. The rotor assembly is supported by self acting hydrodynamic liquid film bearings. Precision labyrinth clearance seals meter internal leakage providing cooling to the bearings and motor, and managing pressure within the motor cavity, preventing vapor generation in the bearings. The non contact bearings and seals ensure reliable long term operation for many thousands of hours and start stop cycles. The motor operates in cryogenic hydrogen, reducing copper losses and maximizing specific power. The impeller inlet geometry, including inducer and operating speed are optimized to minimize cavitation potential. Materials of construction have been selected to eliminate hydrogen embrittlement concerns, enabling the pump to remain fully submerged in LH2 in transit until operation is required. The resulting design achieves a net efficiency of 69% and total electrical input of 4 kW (both values include estimated motor and electronics losses). It is very compact, with a predicted size of only 10.8 in. × 6.2 in. In Phase I, we proved the feasibility of the cryogenic propellant pump by developing a preliminary design, predicting its overall performance, and demonstrating its radial impeller with inlet inducer by testing in simulant cryogenic fluids. In Phase II, we will optimize the pump design, fabricate an integrated pump assembly, demonstrate its steady-state and transient performance at representative conditions in LH2, and deliver it to NASA for further performance evaluation.