Effect of a Biphase Lubricant on Half Frequency Whirl in a Full Journal Bearing

Abstract

It is shown that a liquid–solid biphase lubricant can stabilize the motion of a rigid rotor in a full-journal bearing. The biphase lubricant is a uniform dispersion of Teflon particles in an SAE 20 lubricating oil. The stabilizing effect of nine combinations of particles and oil at two rotor speeds are investigated (particles of 25, 32, and 40 micron dia in concentrations of 5, 10, and 15 percent by weight, respectively, at rotor speeds of 1200 and 1800 rpm). These results are compared with the computed and measured orbits of the journal center relative to the bearing center when the same lubricating oil is used alone. In the analysis account is taken of the forces associated with the crushing of the Teflon particles and the usual inertia and fluid-film forces. A rigid-rotor, full-journal bearing apparatus was used to measure the orbits described. Agreement between computed and measured results was generally good. Both support the conclusion that a liquid-solid biphase lubricant can, in fact, stabilize the motion of rotors in full-journal bearings.