Some Experiments on Instability of Rotors Supported in Fluid-Film Bearings

Experiments are conducted on two rotors, weighing 40 and 187.5 kg, respectively, and supported in cylindrical bearings with two axial grooves. The journal position in the bearing is measured by built-in capacitance displacement probes, and the dynamic behavior is monitored by pressure probes. The self-excited whirl at the threshold speed of instability, as well as the influence of unbalance on the whirl frequency, is investigated in detail. By adding damping at the supports, the heavier rotor is stabilized and operated up to 330 Hz. Correlation with theoretical predictions is presented.