Contribution to the Theory of Oil Whip

Oil whip of a rotor consists in a whipping or whirling motion of the rotor shaft, of frequency essentially equal to the critical frequency of the rotor; it occurs at rotor speeds roughly exceeding double the critical speed. In the paper it is shown that an explanation of oil-whip phenomena, at least for small eccentricities, can be obtained from the equations of hydrodynamic forces and the dynamical equations of motion, provided that the hydrodynamic-force expressions be modified to delete from the oil forces the hitherto included contributions from the regions of negative pressure.