Analysis of Rotor Dynamics Characteristics of Jeffcot Rotor-Floating Ring Bearing System Including Heat Transfer 2021-01-0641

With the increasing application of turbochargers on internal combustion engines, there are more and more examples of vibration faults in turbochargers. The dynamics characteristics of the bearing-rotor system of engine turbocharger systems have received extensive attention. The bearing-rotor system dynamics is a discipline that couples bearing fluid lubrication research and rotor dynamics. The lubrication characteristics of the bearing and the dynamic characteristics of the rotor must be studied at the same time. In this paper, the lubrication model of floating ring bearing of turbocharger is established, and the viscosity lubrication condition considering heat transfer effect is obtained. Based on the Capone cylindrical bearing oil film force model, the nonlinear oil film force equation of the floating ring bearing is deduced. Further the dynamic model of the Jeffcott rotor-floating ring bearing system is established. The rotor dynamic characteristics of Jeffcott rotor floating ring bearing system are analyzed through inputting lubrication viscosity condition. In addition, the influence of heat transfer factors on rotor dynamics is analyzed. The research results show that when the heat transfer effect is considered, the rotor and the floating ring do a double periodic motion under low-rotatory-speed conditions. They do almost periodic bifurcation motion when the rotatory speed increases. Compared with excluding heat transfer, the rotor loses static balance and starts to vibrate earlier as the speed increases, and the rotor vibrates more severely under medium and high-speed conditions. When considering the effect of heat transfer, the rotor will no longer converge at 20000 rpm while it occurs at 40000 rpm without including heat transfer.