TURBULENT-FLOW FOIL BEARINGS FOR CRYOGENIC APPLICATIONS

Fluid film foil bearings are an innovative bearing technology proposed for rotor support in cryogenic turbomachinery. These bearings offer s ystem life and rotor speeds currently unachievable with rolling elemen t bearings alone. An isothermal analysis for the turbulent bulk-flow o f a variable properties liquid in a foil bearing with a simple elastic matrix is introduced. Numerical predictions compare the static and dy namic force performance of a three pad foil bearing with a rigid surfa ce bearing for a high speed application in liquid oxygen. The major ad vantages of the foil bearing are immediately apparent, namely linearit y in the load versus eccentricity curve, uniform rotordynamic coeffici ents, and overall unsurpassed stability conditions. The effects of exc itation frequency and the foil structural damping on the dynamic force coefficients are discussed.