Thermal Management Phenomena in Foil Gas Thrust Bearings

Thrust foil gas bearings operate at high speeds on a very thin fluid film which experiences high shear. Shear induced viscous losses result in localized heating which must be managed to prevent thermal distortions and failure. The current work examines the need for thermal management in thrust foil bearings as evidenced by reduced performance in uncooled bearings. Measured bearing power loss is a few hundred watts from twenty-five to fifty-five krpm (89–196 m/s runner surface velocity based on mean bearing diameter). Modeling of the thrust runner demonstrates a potential for stress-induced running surface deformations greater than the gas film thickness (>10 μm), and radial temperature gradients in the bearing foils can exceed a few degrees Celcius per millimeter. Air flow forced through the foil structure achieves improvements in bearing load capacity and demonstrates a need for increased understanding of the thermal environment in these bearings.