Investigation of compliant foil bearings for long-life liquid hydrogen pumps

摘要

In Phase 1 of the program, the feasibility of using a foil bearing in an LH2 pump was analyzed. The preliminary pump design used in that analysis consists of a two-stage impeller radially supported by a foil journal bearing. Axial thrust loads are supported outside of the pump section by an angular contact ball bearing. It is concluded in the Phase 1 report that foil bearings are suitable for LH2 pumps, and that a journal foil bearing diameter of 1.75 to 2.00 in. with a length-to-diameter ratio of 1.0 to 1.5 is adequate for the preliminary pump design. During Phase 2 bench tests were run to verify the feasibility study conducted in Phase 1. The original Statement of Work called for direct bearing tests in an LH2 environment; however, after studying the test facilities and equipment available at AiResearch, it was agreed to reduce the scope of the test program to stay within budget. In the revised work statement, feasibility is to be verified by testing an existing foil journal bearing in water under conditions hydrodynamically similar to those in an LH2 pump. An existing AiResearch bearing of 1.75 in. diameter by 2.4 in. long was selected, and all intended tests were successfully completed. Important bearing performance parameters, including loading capacity, running torque, shaft dynamics, and wear were monitored. The feasibility of using foil bearings in LH2 pumps is thus verified.