Effect of load direction, preload, clearance ratio, and oil flow on the performance of a 200 mm journal pad bearing

Journal pad bearings are widely used in industry, particularly in high-speed applications. Previous experimental work with bearings of this sort has tended to be fragmented and mainly confined to smaller and relatively lightly loaded bearings. The purpose of this paper is to present temperature measurements and derived values of power loss from a new, extensive experimental program involving a 200 mm diameter journal pad bearing, operating at speeds up to 105 mls and loaded at specific pressures up to 4.14 MPa. The program was designed to isolate some important design parameters and determine their effect on bearing temperatures and energy consumption. Bearing clearance, journal pad preload, the direction of the applied load, and the impact of radically reducing the amount of lubricant supplied to the bearing are all examined. In particular, it is found that the load line direction has a substantial impact on maximum pad temperature. It is also shown that large reductions in the volume of oil supplied to the bearing are possible, leading to useful energy savings without compromising reliability. One of the most interesting features of the results presented is the significant effect on pad temperature of an apparent laminar to turbulent transition in the lubricant which occurres at high operating speeds. It is hypothesized that the transition takes place in the oil which flows around the pads rather than in the hydrodynamic films. It is anticipated that the information contained in the paper will be of interest and use to members of the academic community, bearing designers, and bearing operators.