Dynamic Stability of Gimbaled Spiral-Grooved Thrust Bearing

Abstract

A general, easily implemented technique is developed by which stability maps may be determined for gimbaled, gas-lubricated, spiral-grooved thrust bearings. This technique is based upon the spectral analysis (frequency domain) method in which the neutrally stable states of the stator-gimbal system are determined through solution of the system’s characteristic equations. The method has proven effective for conducting low-cost investigations of the sensitivity of system instability thresholds to changes in various system design parameters. Containing data valid for a wide range of gimbal inertias, stability maps are presented for a range of bearing compressibility numbers, for several bearing geometries, and for several values of mechanical damping in order to illustrate both the power of the technique and also its effectiveness. Limited experimental information which is presently available verified the essential features of the corresponding stability maps. The technique has been reduced to a form usable in the design of gas bearings for use in gas turbine engines.