Auxiliary Bearings for Magnetically Supported Rotors

Auxiliary bearings will be critical components of advanced gas turbine engines using magnetic bearings to support the engine spools. Because of the high temperature in the bearing compartments conventional oil-lubricated bearings cannot be used either as the main or auxiliary bearings. Although solid-lubricated bearings under development are capable of supporting high loads at high temperatures, their short lifetime limits their use for man-rated aircraft engines. A novel auxiliary bearing design for magnetically supported rotors in high-temperature gas turbine engines has been developed. The design incorporates a pressurized gas bearing and solid lubricated touch sleeves to achieve a bearing system with extended life at high temperatures, no wear during normal operation, and significant over-capacity to handle aircraft maneuvers. The auxiliary bearing design integrates the pressurized gas bearing into the magnetic bearing stator, resulting in a compact systems with synergistic benefits to both the magnetic and gas subsystems. In Phase I the feasibility of the proposed bearing concept was assessed by developing a preliminary design of the hybrid magnetic/gas bearing and characterizing the auxiliary bearing performance. In Phase II, we propose to build and test a set of hybrid bearings. Creare will work with engine manufacturers in Phase III to incorporate the auxiliary bearings into advanced turbine engines.