Influence Of Fixed And Floating Characteristics Of Sliding Bearings On Vibration Characteristics Of Turbocharger Rotor System

With the rapid development of high-speed trains today,diesel locomotive still occupies an important position.The installation of supercharger on the internal combustion engine can improve the power of the internal combustion engine while reducing the loss of fuel and the damage to the atmosphere.But with the increasingly widespread application of supercharger,people put forward higher requirements for its durability and reliability in the process of use.The instability of the turbocharger rotor will affect the reliability of the operation of the turbocharger.As an important part of the rotor system,the sliding bearing,whether the bearing is fixed or not,will have a great impact on the stiffness and damping of the bearing,and then affect the vibration characteristics of the rotor system.Based on the Reynolds equation of unsteady motion of sliding bearings,the finite difference method is used to solve the nonlinear oil film forces under fixed,semi-floating and floating conditions,and the stiffness and damping distributions under a wide range of working speeds are obtained.The finite element model of the turbocharger rotor system was established,and the critical speed,vibration response and stability of the rotor system under a wide range of working speeds were simulated and analyzed.The results show that the critical speed under the fixed bearing support is higher than that of the semi-floating bearing support than that of the floating bearing support.The maximum shaft vibration displacement of the floating bearing support is greater than that of the fixed bearing support than that of the semi-floating bearing support,that is,the semi-floating bearing is more beneficial to reduce the shaft vibration displacement.The minimum logarithmic attenuation rate under the floating bearing support is greater than that of the semi-floating bearing support and that of the fixed bearing support,that is,the floating bearing is more conducive to improving the stability of the system.