Analysis Of Dynamic Characterists On Turbocharger Rotor With The Effect Of Gas

The turbocharger can improve the power and fuel economy of the diesel engine by increasing the inlet charge density,and at the same time it can also improve the effective thermal efficiency and reduce the harmful ingredients in the exhaust.So the turbocharger has been widely used gradually.In this paper,the turbocharger that is studied which is belongs to the typical high-speed rotating machinery has a very high speed of rotation.And the rotor-bearing system is its most important core components.People have a high technical requirement about the working performance,stability and service life of the rotor-bearing system.In the paper caculation model based on finite element method of the turbocharger rotor system is established,the modal analysis under the action of fluid-structure coupling is researched and the dynamic behaviour of turbocharger rotor is calculated.Firstly,the impeller internal flow analysis model is established based on IGG/AutoGrid5 and CFX software,and the flow characteristics of the compressor is calculated and analyed in order to get the surface pressure distribution of the compressor and turbine impeller,that can provide basis for the fluid-structure coupling analysis.Secondly,the finite element model of rotor-bearing system is established and a data connection between solid and fluid field is established based on the Workbench platform.Based on the fluid-structure coupling model,modal of the rotor system with and without the gas force is separately analyzed,and the influence of prestress from the gas on modal vibration shape and frequency is researched.Finally,the first and second order critical speed of rotor system are calculated based on the calculation model of rotor dynamic characteristic,and the bearing stiffness and span are changed,the influence of bearing stiffness and span on critical speed is concluded.The analysis of Harmonic response and transient response is carried out with simplified dynamic model of rotor system,and transient response of the rotor in the acceleration process is calculated separately under different bearing stiffness or different bearing stiffness in order to get the influence of acceleration and bearing stiffness on transient response of the rotorbearing system.