Design and Optimization of a Passive Magnetic Thrust Bearing
Lasko, Thomas Matthew
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High-speed turbomachines present a number of unique challenges and problems. Large centrifugal forces create high stresses in rotating components, friction leads to elevated temperatures and component failure, and rotordynamic instability makes control difficult. The weak link in these high-speed systems is often the bearings because they provide the interface between the rotating and stationary components. Traditional bearings often fail in these conditions, especially when relatively large force capacities are required. In miniature gas turbines for unmanned aerial vehicle (UAV) applications, traditional bearings exhibit a typical lifetime of only 25 hours due to excessive axial loading. This research presents a passive magnetic thrust bearing design that reduces the effect of axial loading, therefore dramatically increasing expected lifetime and reducing the required maintenance. A procedure for designing and optimizing the bearing is developed, including equations for quickly producing new geometries for various load capacities. A specific bearing design for a UAV gas turbine application is designed, fabricated, and tested at both static and dynamic conditions. The results validate the design concept as well as the finite element models and associated analyses. The research concludes with suggestions for future research as well as possible improvements to the design based on the results and lessons learned throughout the design, fabrication, assembly, and testing phases.