Static reduction of viscous friction and stability of rotor motion in actively lubricated fluid film bearings.

Adjustable fluid film bearings allow implementing additional functions in rotary machines and expand the range of their operating characteristics in comparison with conventional passive bearings. The effect of static reduction of viscous friction in actively lubricated bearings can be achieved by adjusting the position of the rotor in the gap. The variety of possible implementations of such bearings requires studying this effect in more detail. The article considers the influence of significant bearing parameters, such as the gap shape and the lubricant viscosity, on the implementation of the effect of static friction reduction. Water and oil are considered as the examples of the more and the less viscous lubricants that are often used in machinery, as well as circular and elliptic gap profiles are compared in the context of the studied effect. Series of computational experiments were carried out for different combinations of these factors to obtain the information about the tribological and dynamic behavior of the rotor-bearing system under such conditions. A simplified "soft" approach to the implementation of static friction reduction requiring no rotor position tracking is also proposed and analyzed. The results of the work make it possible to determine the limits of applicability of the considered approaches depending on the configuration and operational features of rotary machines in order to improve their performance by applying modern solutions in bearings. [ABSTRACT FROM AUTHOR]