Research On The Nonlinear Dynamics Of Rotor-Bearing System Of Turbine

For the practical rotor-bearing system, it's necessary to investigate thoroughly nonlinear dynamic behaviors, instability and the influences of operating parameters on dynamic stability of rotor-bearing system, because it has great impact on accident prevention and safety operation. So it is full of realistic signification and extensive engineering background to study on the nonlinear dynamics of turbo and finally to design them by using nonlinear method. The main contents are as follows:Firstly, in this dissertation, the model of the practical rotor-bearing system of turbine is established by FEM (Finite Element Method) and the rule of critical speed changing with the increment of bearing rigidities is found. The dynamic characteristics of rotor-bearing system are simulated with different bearing rigidities.Secondly, the model of rotor with single-disc is established by FEM (Finite Element Method). The Newmark method is applied to solve the equation of motion. By the numerical calculation, the nonlinear dynamical stability information of high-pressure rotor-bearing system supported by column bearings is simulated separately during the speed ascending and descending process. The typical characteristics of the oil whip of the system are calculated under the nonlinear model of oil film force.Finally, nonlinear dynamic responses of turbine high-pressure rotor-bearing system within broad range parameters and under speed up-down conditions are studied by using Newmark method. The process and characteristics of oil whirl and whip in rotor system are successfully simulated. The rule of the amplitude of turbine high-pressure rotor-bearing system with the changing of the clearance of the bearing, the eccentricity of rotor, the slenderness ratio and oil viscosity are presented by numerical results.The analysis results of this dissertation provides theory basis for describing and predicting the nonlinear instability phenomenon caused by oil film force in real engineering application, and also provides theory basis for nonlinear designing of turbine sets to choose its geometry parameters.