&nbsp;Effect of Unsteady Oil Film Force on the Rotors with Loose Disc

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Journal of Vibration and Shock ›› 2019, Vol. 38 ›› Issue (17) : 268-275.

Effect of Unsteady Oil Film Force on the Rotors with Loose Disc

LIU Jie1, LI Zhinong1, LU Wenxiu2

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Abstract

When disk and shaft of a rotor system are loose, oil whirl can affect shaft motion trajectory, and lead to rubbing between disk and shaft, this rubbing can cause large disturbance to oil whirl, so study on effects of unsteady oil film force on rotor system with loose disk and shaft is valuable.Here, dynamic differential equations of a rotor-bearing system with loose disk and shaft were established with Hertz impact-contact theory and unsteady and nonlinear oil film force.The fourth-order Runge-Kutta method was used to solve these equations, and the numerical simulation results were verified with tests.The effects of unsteady oil film force on disk rotating state and effects of oil film clearance on vibration characteristics of the rotor system were discussed.The results showed that disk dimensionless rotating speed has two states of high rotating speed and low one; when the rotor system does not consider oil film force and its disk rotating speed enters high speed state, its shaft rotating speed is lower than that of the rotor system considering oil film force; with increase in oil film gap, bearing center motion trajectory undergoes quasi-periodic motion state, chaos one and quasi-periodic one, and its shape becomes more and more slender; shaft center motion trajectory is like a rotating sector without obvious variation law, frequency components of the rotor system are basically unchanged, but their amplitudes have different changes; the study results provide an important reference for modeling of rotor systems with loose disk and shaft and studying their dynamic characteristics.

Key words

rotors with loose disc / nonlinear vibration / hertz contact / fault diagnosis / unsteady oil film force

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LIU Jie1, LI Zhinong1, LU Wenxiu2. Effect of Unsteady Oil Film Force on the Rotors with Loose Disc[J]. Journal of Vibration and Shock, 2019, 38(17): 268-275

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