Research On Dynamic Behaviors Of A Flexible Rotor System With Squeeze Film Damper

Industry rotating machinery,especially aircraft engine,is being developed towards the direction of higher speed and more flexibility to pursue larger operating range,which puts forward new requirements for the accuracy of manufacture,running speed,capacity and working environment.While the rotating machinery may be broken down due to the effects of the severe vibrations through the first critical speed or much higher critical speed,high temperature,friction,deformation,crack in working process.These faults can lead to disastrous accidents.So the damper design for support structure is becoming a hot topic in the rotor dynamics field.The research achievement in this field can not only be beneficial to the aircraft engine development,but also the high-speed rotor systems for both domestic and industrial use.Squeeze film dampers are prepared as an efficient method to solve this problem.The main research contencts in this paper are as follows:First of all,the ball bearing model,traditional squeeze film damper(TSFD)model,fluent-ring squeeze film damper which has a double layer oil-film(FSFDD)model,fluent-ring squeeze film damper which has a single oil-film(FSFDS)model,have been established.These SFDs models are validated by coomparing the system responses obtained in this paper with the results in literatures.Aiming at a flexible rotor system,this paper established a dynamic model for this system based on finite element method.The simulated responses were compared with the experiment results in literature.The natural characteristics of the rotor systems with three kinds of SFDs models support were also compared with those under the stiffness support.The effects of structure parameters such as elastic stiffness,numbers of balls,ball bearing clearance,oil-film clearance,fluent-ring mass,the unbalance moment on the system responses under the stable and transisent states were discussed.The root-mean-square value,power spectral density,fourier transform and time domain waveforms were applied to analyze the effects of above parameters on the vibraton response of the flexible rotor system.In addtion,the influences of the angular acceleration,sudden unbalance moment on the system vibration responses were also investigated when the system goes through the first and second critical speeds.Finally,the vibration characteristics of the system under four kinds of support models were compared under the same excitation condition.Through the comparsion of the natural characteristics and vibration responses under stable state and traisnet state(run-up and run-down process,and sudden unbalance),damping capacity provided by the squeeze film damper were investigated to evaluate the vibration reduction properties and available work range for these dampers.In the end,the insufficient research part in this paper and the work in the future research were pointed out.