DYNAMIC FORCE RESPONSE OF SPHERICAL HYDROSTATIC JOURNAL BEARINGS FOR CRYOGENIC APPLICATIONS

Hydrostatic journal bearings are ideal elements to replace roller bear ings as rotor support elements in cryogenic turbomachinery. These bear ings will be used for primary space-power applications due to their lo ng lifetime, low friction and wear, large load capacity, and direct st iffness and damping force coefficients. The performance characteristic s of turbulent flow, orifice compensated, spherical hydrostatic journa l bearings are presented. These bearings allow tolerance for shaft mis alignment without force degradation and are able to support axial load s, thus providing a design configuration which could be used efficient ly on high-performance turbomachinery. Bulk-flow mass and momentum equ ations for the motion of a variable properties liquid on the thin film bearing lands are solved numerically. Predictions of load capacity an d force coefficients for a six recess, spherical hydrostatic bearing i n a liquid oxygen environment are presented. Fluid film axial forces a nd dynamic coefficients of a magnitude about 20 percent of the radial load capacity are calculated for the case analyzed. Fluid inertia effe cts, advective and centrifugal, are found to greatly affect the static and dynamic force characteristics of the bearing studied.