The influence of floating ring bearing outer oil film clearance on subsynchronous vibration of turbocharger rotor system

The outer oil film clearance is an important parameter of the floating ring bearing, which directly affects the damping coefficient and subsynchronous vibration of the turbocharger rotor system. Unreasonable outer oil film clearance can cause severe subsynchronous vibration and lead to nonlinear vibration accidents. This article first analyzes the influence of outer oil film clearance on the damping coefficient of floating ring bearings through theoretical analysis and finite element simulation. Then taking a certain type of gasoline engine turbocharger rotor system as the research object, the finite element model of the floating ring bearing rotor system is constructed, and the nonlinear transient response of the rotor system is analyzed by the Newmark direct integration method. Through this simulation, the influence of different outer oil film clearances on the nonlinear subsynchronous vibration of the rotor system is obtained. The results show that when the outer oil film clearance increases from 0.030 mm to 0.036 mm, the maximum amplitude of the outer oil film subsynchronous vibration increases from 0.01 mm to 0.16 mm, and the maximum amplitude of the inner oil film subsynchronous vibration decreases from 0.05 mm to 0.02 mm. This is because as the outer oil film clearance increases, the outer oil film damping coefficient decreases and the inner oil film damping coefficient increases. In the design process, the outer oil film clearance should be appropriately designed to adjust the subsynchronous vibration of the inner and outer oil film of the rotor system, so as to minimize the total subsynchronous vibration and improve the stability of the system. This paper can provide a theoretical reference for the dynamic design of the floating ring bearing rotor system.