Development of Foil Journal Bearings for High Load Capacity and High-Speed Whirl Stability

Heshmat, H., Shapiro, W. and Gray, S. “Development of Foil Journal Bearings for High Load Capacity and High-Speed Whirl Stability,” (1981) American Society of Mechanical Engineers (Paper), 8 p., (1982) Journal of Lubrication Technology, ASME Transactions, Volume 104 (2), pp. 149-156.

Air lubricated foil bearings have demonstrated excellent promise for several applications such as aircraft air cycle machines, gas turbines, turbochargers and other high-speed turbomachinery. The foil bearing will deform as hydrodynamic pressure is generated. They can be constructed to deform in an advantageous manner with respect to the flight application whether it be for high load capability or for high-speed operation. It is also possible to introduce frictional damping by causing rubbing as deformation takes place and by selecting material combinations that will optimize the coulomb damping effect.               The development of two separate journal bearing configurations are described in this paper. The first is a three-pad bearing designed for superior whirl characteristics. The second is a single pad bearing designed for high load capacity and stabilized for high speed operation by coulomb friction from copper coated rubbing surfaces. Without this stabilizing mechanism (coulomb friction) high pressure and consequent high load capacity due to high speed hydrodynamic generation could not be achieved because of premature fractional frequency whirl.

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