Research On The Influence Of Floating Ring Bearing Parameters On The Vibration Characteristics Of High-Speed Light-Load Turbocharger Rotor System

Turbocharger speed high and mass light,it is a typical high-speed light-load type rotor,which is supported by floating ring bearing.The operating parameters and structural parameters of floating ring are closely related to the vibration characteristics of turbocharger rotor system.In this thesis,a finite element model of a turbocharger rotor floating ring bearing system is constructed.Through linear analysis,nonlinear analysis and experimental test,the influence of operating parameters and structural parameters on the lubrication and dynamic characteristics of floating ring bearing is analyzed,and the effect of various parameters on the vibration response of the rotor system is studied.The main contents are as follows:(1)This thesis introduces the structural characteristics and modeling principles of the high-speed and light-load turbochargers.By deriving the dynamic pressure oil film equation of the floating ring bearing and the rotor system vibration differential equation,a finite element model of the turbocharger rotor-floating ring bearing system is constructed.The vibration mode,critical speed,linear and nonlinear vibration response characteristics of the rotor system are analyzed.It is found that the rotor system exhibits linear characteristics at low speed and non-linear characteristics at high speed.(2)Considering the influence of operating parameters on the vibration response of turbocharger,the influences of ring speed ratio,inlet oil temperature and oil supply flow on the lubrication characteristics of floating ring bearing are analyzed.The nonlinear transient response of the rotor subsystem is analyzed by the Newmark integration method.The Waterfall and Colormap spectrum of the rotor system under the influence of various operating parameters are obtained.The nonlinear vibration mechanism of the rotor subsystem is explored under the influence of various operating parameters.It is concluded that reasonable control of the ring speed ratio,inlet oil temperature,and fuel supply flow can effectively reduce the vibration response of the turbocharger rotor system.(3)In view of the design and manufacture of the structural parameters of floating ring bearing,the influence of the inner and outer axial length of floating ring and consider bearing manufacturing tolerances for assembly clearance on the dynamic characteristics of floating ring bearing is analyzed.Through the harmonic response analysis method,the Waterfall of rotor system under the influence of various structural parameters is obtained,the influence of the axial length of floating ring and assembly clearance on the vibration characteristics of rotor system is studied.It is found that reducing the inner axial length of the floating ring andincreasing the inner oil film clearance can reduce the subsynchronous vibration amplitude of the rotor system and improve the stability of the rotor system.(4)Design the relevant parts of the turbocharger rotor test bench,and conduct the steady-state and transient speed-up experiments of the rotor system under actual working conditions.The critical speed of the rotor system and the vibration response of the rotor system at two extreme inlet oil temperatures were obtained.Through experimental verification and error analysis,it is found that the inner and outer oil film whirl and whip rules of the rotor system are basically consistent with the simulation results.It shows that the constructed finite element model and the research method adopted are reasonable.