Effect of Inlet Oil Temperature on Vibration Characteristics of High-speed Light-load Turbocharger Rotor under Long Period and Variable Speed

The inlet oil temperature of high-speed and light-loaded turbocharger system changes dynamically under the operating conditions of long period and variables speed, thus changing the vibration characteristics of the rotor system and even leadi ng to nonlinear vibration accidents. High-speed and light-load turbocharger system for a certain type of gasoline engine is studied. The variation of minimum thickness and eccentricity ratios of inner oil film in floating ring bearing with different inlet oil te mperature is analyzed. The dynamic finite element model of turbocharger rotor-floating ring bearing system is constructed. Under the turbocharger speed up experiment and simulation calculation, adopting Newmark integral method to analyze the nonlinear transient response of the rotor system, the waterfall and Colormap of the rotor system are obtained under different inlet oil temperatures. Exploring the influence of inlet oil temperature on vibration response characteristics of rotor system. The results show that when inlet oil temperature rises from 50 ℃ to 130 ℃, the inner oil film minimum thickness decreases, the ring speed ratio and eccentricity ratios increase, and the whip amplitude of the inner oil film decreases gradually. But the rotational speed of the journal is earlier approximately by 30% when inner oil film whip and outer oil whirl, the outer oil film whirl amplitude is gradually increased. Considering the inner and outer oil film whirl and vibration amplitude, the rotor vibration reaches to the lowest level when the inlet oil temperature is about 90 ℃. Such findings can provide theoretical reference for future design of high speed and light-loaded turbocharger systems with intelligent anti-vibration performance feature.