Vibration Characteristics Of Turbocharger Rotor System Considering Floating Ring Bearing Internal Thread Weaving

The internal thread weave parameters of the floating ring bearing can change the thickness of the oil film area,resulting in changes in the dynamic characteristics of the floating ring bearing oil film,which affects the operational stability and operating life of the turbocharger rotor-bearing system.In this paper,we take a gasoline engine turbocharger floating ring bearing-rotor system as an example,construct a floating ring bearing hydrodynamic model and a turbocharger floating ring bearing-rotor system finite element dynamics model,and use CFD combined with finite element dynamics to analyze the effect of internal thread weave parameters on the dynamic characteristics coefficient of the bearing oil film and the vibration characteristics of the rotor system,and the experimental bench was built to verify the analysis results.The main contents are as follows:(1)Based on the fluid lubrication theory,the controlling equation of oil film of floating ring bearing with surface weave depth is derived,and the relationship between the internal thread weave depth and the oil film characteristics of floating ring bearing is revealed.A hydrodynamic model of the oil film of a floating ring bearing with internal thread surface weave is constructed,and post-processing analysis is performed using CFD software for UDF programming and dynamic meshing,The analysis results of both CFD software and Dy Ro Be S software were also compared to validate the model.(2)A hydrodynamic model of the oil film of a floating ring bearing with different internal thread weaving was constructed,and the effects of changes in thread weaving depth,position and number of turns on the dynamic characteristics of the oil film of the floating ring bearing were analyzed to investigate the influence of different internal thread weaving parameters on the dynamic characteristics of the oil film of the floating ring bearing,and it was found that a reasonable design of internal thread weaving degree,position and number of turns could improve the dynamic characteristics of the oil film of the floating ring bearing.(3)A dynamic model of the turbocharger floating ring bearing-rotor system was established and the Newmark integration method was used to study the effects of changes in the depth,position and number of turns of the threaded fabric on the vibration characteristics of the rotor system,and the variation of the vibration response of the rotor system under different fabric parameters was obtained.Finally,the critical rotor speed and rotor amplitude were experimentally verified in a turbocharger high-speed balancing machine and a turbocharger rotor system speed-up test bench at double frequency.