Notes12b Hydrostatic Bearings TRIBGROUP （Notes12b静压轴承TRIBGROUP）.pdf

NOTES 12(b) HYDROSTATIC JOURNAL BEARINGS Summary In a hydrostatic bearing an external source of pressurized fluid forces lubricant between two surfaces; thus enabling non-contacting operation and the ability to support a load. Hydrostatic bearings can support large loads without journal rotation and provide large (accurate and controllable) direct stiffness as well as damping (energy dissipation) coefficients. Hydrostatic bearings rely on external fluid pressurization to generate load support and a large centering stiffness, even in the absence of journal rotation. The load capacity and direct stiffness of hydrostatic bearings do not depend on fluid viscosity, thus making them ideal rotor support elements in process fluid pumps. Current applications intend to replace oil lubricated bearing with hybrid bearings to improve efficiency with shorten rotor spans and less mechanical complexity. Current cryogenic liquid turbopumps implement hydrostatic bearings enabling an all fluid film bearing technology with very low number of parts and no DN limit operation. Details on the bulk-flow analysis of turbulent flow hydrostatic bearings are given along with the discussion of performance characteristics, static and dynamic, for hydrostatic bearings supporting a water pump. Angled liquid injection produces a hydrostatic bearing with unsurpassed dynamic force and stability characteristics. Introduction Hydrostatic bearings derive their load capacity not from shear flow driven effects (hydrodynamic wedge and surface sliding) but rather from the combination of pressure versus flow resistance effects through a feed restrictor and in the film lands. Figure 1 depicts thrust and radial hydrostatic bearing configurations for process fluid lubricati