Viscous Torque in a Spherical Gas Bearing

Abstract

rpHE HYDROSTATIC GAS BEARING lias been used in in•*• dustry for many years. On the other hand, while the principle of the hydrodynamic gas bearing has also been known for many years, it has only recently been applied. Not surprisingly, its first application has been in the nuclear field, where bearing lubricants would be adversely affected by radiation. Possibly even more significant has been the application of the hydrodynamic gas bearing in the gyromotor field, where the fantastic accuracies required have led to experimentation with everything from "atomic" to cryogenic gyros. It is quite likely that the current interest in, and work on, the spherical gas bearing will lead to other applications because of its inherently high stability and long life. The gyro motors being developed for air and space applications are, by the nature of these applications, limited in size and, thus, power. Aside from initially bringing the gyro wheel up to synchronous speed, power is necessary to overcome the windage loss of the motor and the viscous loss in the gas-bearing gap. I t can be readily seen how important it is to determine accurately the power requirements in such a small motor. The purpose of this paper is to show how to calculate viscous torque in a spherical gas bearing when the bearing eccentricity e is taken into account. For a high value of eccentricity—i.e., above 0.5—the error introduced by neglecting the eccentricity effect is large, and should not be neglected. An expression for the percentage of this error, which is introduced into the cal-