The Role of Cavitation in Whirl Instability in a Rotor Bearing, 1: The π-Film Model

Dynamically loaded rotor bearings are frequently observed to perform whirling motions, in which the center of the rotor describes some sort of closed orbit. In this paper we demonstrate, by using numerical computations of whirl orbits in a simple π-film model, the role of cavitation of the lubricant in enabling fluid forces alone to drive such stable orbits for certain ranges of parameter values. For other parameter values cavitation may actually enhance the instability always associated with the effects of fluid forces in a full-film bearing.