Performance evaluation of a single-pad, externally-adjustable fluid film bearing

Abstract

Modern high-speed rotating machinery requires a well-designed support system for the spindle. Circular profiled bearings can offer only a little improvement on the performance. Attention was therefore directed to non-circular forms like lemon bore, offset half, pressure dam and multi-lobe bearings. A notable feature of all these types is their contributions towards the improvement of performance. All such improved bearings, however, retain the essential characteristic of being reactive to the operating loads and conditions. Another limitation is that the bearing surface cannot be altered while the bearing is in operation. Hence, an adjustable bearing is one option. This paper deals with the steady state performance evaluation of a single-pad, externally-adjustable fluid film bearing. The bearing has an aspect ratio of 1.0, and operates over a wide range of eccentricity ratios and adjustments. Three load-offset positions (β/χ) of 0.45, 0.50 and 0.55 are considered in the present analysis. Steady state performance characteristics of the bearing are in terms of attitude angle, load carrying capacity, oil flow, friction variable and Sommerfeld Number. Steady state form of Reynolds equation in two dimensions is solved numerically using the finite difference method. The effect of tilt and radial adjustment on the steady state performance characteristics are studied and presented in the form of charts and tables.