AN ANALYSIS OF GAS-LUBRICATED, MULTILEAF FOIL JOURNAL BEARINGS WITH BACKING SPRINGS

This paper describes the development of a new analysis technique that was used to evaluate the performance of a class of gas-lubricated jour nal bearings. The surface of these bearings is made up of preformed, l eaf-type, compliant foils that are anchored to the bearing housing by spacer keys. Each leaf overlaps an adjacent leaf. Beneath each foil an d attached to the inside of the bearing housing is a strip of backing spring. The stiffnesses of various foil bearing structures are modeled and presented as influence coefficients. Unlike conventional approach es, the solution of the governing hydrodynamic equations dealing with compressible fluid is coupled with the structural resiliency of the be aring surfaces. The distribution of the fluid film thickness and press ures, as well as the shear stresses in a finite-width journal bearing, are computed. The solutions include values of bearing stiffness coeff icients due to both structural and hydrodynamic stiffnesses. The analy sis, which is conducted for multileaf configurations by varying the nu mber of leaves, uncovers the effects that the various structural, geom etric, and operational variables have on bearing behavior. Also discus sed are design guidelines with regard to the number of leaves, the deg ree of compliance, and bearing operational parameters.