The manufacturers of high speed turbomachinery are concerned with the accurate prediction of rotor response and stability. One major factor in the placement of system critical speeds and amplification factors is the stiffness and damping of both the fluid-film bearing and support structure. Typical calculated results for tilting-pad fluid-film bearings have neglected the influence of the point or line contact of the pivot support for the individual pads. This paper will review the equations developed considering the Hertzian contact stress and deformation theory and present the equations for pivot stiffness necessary for inclusion in tilting pad bearing computer programs. In addition, the influence of various standard pivot designs will be compared for typical fluid-film bearing stiffness and damping characteristics.

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The equilibrium position of multi-ring seal assemblies is of major importance to the designer of high pressure centrifugal compressors. Typical computer codes now use a curve-fit of the Short Bearing Sommerfeld Number for eccentricity evaluation with the assumption that all rings in the assembly will always operate at the same eccentricity. The results from the recently developed seal analysis program, SEALS, have shown that the equal eccentricity assumption for multi-ring seals is questionable. This paper will review the analysis procedure used in SEALS, and present the results of an eccentricity evaluation comparison with a seal analysis program currently being used in industry.

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