Experimental Investigations of Novel Compound Bearing of Superconducting Magnetic Field and Hydrodynamic Fluid Field

Long-life and high-reliability bearing is a key technology for developing the next generation of reusable liquid rocket turbopumps. We proposed a concept of superconducting compound bearing to combine the advantages of the superconducting magnetic field and the hydrodynamic fluid field. At the start-up, stop, and low-speed stages, the turbopump rotor system will be suspended by superconducting magnetic field to avoid mechanical friction and wear. The participation of hydrodynamic fluid field will ensure the stability during high-speed operational stage. An axial-type superconducting compound bearing with six tilting pads was erected, and an experimental verification of compound feasibility was conducted on an established testing device. The maximum rotational speed for experiments was 10 000 rpm, and the minimum bearing clearance was 100 μm. Due to the temperature rise on the superconducting pads during rotating, the superconducting magnetic force of the bearing decreases obviously versus the rotational speed. When the bearing clearance was decreased to 100 μm, this decay tendency was slowed down after 6000 rpm, even with an increase of 0.8 K in the cooling temperature of the liquid nitrogen container. It was attributed to the generation of hydrodynamic fluid-film force, and the value is 19.2 N at least. The monitored vibration results also reflected the different characteristics of the two physical fields. The verified superconducting compound bearing is a promising alternative for the rolling element bearings in the existing rocket turbopumps.