Performance of Externally Pressurized Grooved Thrust Bearings

Externally pressurized grooved gas thrust bearings for shaft systems were studied both numerically and experimentally. Three thrust bearings composed of a symmetric pair of rings facing a shaft collar were tested. The rings, with inner and outer diameters of 52 and 110 mm, respectively, are equipped with a polar array of eight holes, with a 0.35-mm diameter, distributed on a 65-mm-diameter circumference. The influence of a circumferential groove situated in correspondence with the supply holes is discussed. In particular, two thrust bearings have a rectangular cross-sectional groove of 0.7-mm width and 10- and 20-mu m depth. A numerical model based on Reynolds' equation is used to study thrust-bearing performance in relation to geometry (diameter of supply holes, clearance, and groove dimensions). A test rig is used to monitor thrust-bearing axial load capacity and stiffness, and evaluate damping and stability at different supply pressure rates. Experimental and numerical results are compared and discussed.