Magnetic Bearings for Cryogenic Fluid Management

Cryogenic Fluid Management (Cryogenic Fluid Management) systems aboard spacecraft employ reverse turbo-Brayton cryocooler compressors and turboalternators that require maintenance-free operation up to 400,000 RPM for an operational lifetime of 50,000 hours. At these speeds, traditional rolling element bearings fail due to the friction between the rotating and stationary components and require frequent maintenance due to lubrication requirements. Mainstream proposes a hybrid magnetic bearing system that offers non-contact operation over the full range of rotational rates. The hybrid system employs passive magnetic components to reduce the size, weight, and power required while the remaining active components provide the controllability that is necessary to maintain stable operation in the presence of dynamic loads. In the Phase I, Mainstream will leverage our experience in magnetic bearing and turbomachinery design to optimize, fabricate, and test a bench-scale prototype bearing system. At the end of Phase I, Mainstream will validate the design by measuring the performance of the bearings in terms of load capacity and stiffness under static conditions. In the Phase II, Mainstream will design a full-scale system and integrate the hybrid bearings. At the end of Phase II, Mainstream will demonstrate the system and bring the technology to TRL 6.

NASA applications for the proposed hybrid bearing system include compressors, heat pumps, turboalternators, and turboshaft engines. In general, the technology applies to any high-speed turbomachinery that requires exceptionally long lifetime and maintenance-free operation. Major non-NASA applications include gas turbine engines for UAVs, machine spindles, compressors for thermal management systems, and permanent magnet motors. Mainstream’s hybrid bearing system is also applicable to any rotating machinery that requires oil-free operation, such as medical oxygen systems, or ultra-high efficiency, such as power generation systems.

This is a mature technology (TRL 7+) — the realistic path in is usually NASA's Technology Transfer Program: licensing an existing NASA patent, or a Space Act Agreement to use NASA facilities/expertise directly. NASA also runs a startup licensing program with no upfront fee for companies formed to commercialize a specific NASA technology.

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