Analysis Of Nonlinear Dynamic Characteristics Of Coupled Dual-Rotor And Composite Support System

Gas turbine is an important power equipment in the energy industry,coupled dual-rotor and combined support system is a common type of shaft system used in high power ratio gas turbine at present.As the core component of the gas turbine,the vibration characteristics of the coupled dual-rotor and combined support system play an important role in ensuring the stable operation and reliability of the whole machine.In this paper,the typical coupled dual rotor-combined bearing system of gas turbine is take as the research object,study the nonlinear dynamic response characteristics of the system.Firstly,based on the finite element method,a high dimensional nonlinear dynamic model of high pressure rotor-rolling bearing system is established,and then a nonlinear dynamic model of coupled dual rotor-combined bearing system is established with more degrees of freedom.In the model,the nonlinear support force of rolling bearing,the damping of squeeze film damper,the stiffness of squirrel cage,the shear deformation,the gyroscopic moment and the moment of inertia of the rotor are considered.Then,the numerical methods which are used to compute the high dimensional nonlinear differential equations of motion are compared and analyzed,the numerical methods include Newmark-? method,Newmark-? adaptive step size algorithm,precise integration method,increment dimensional precise integration method and Runge-Kutta method.The accuracy and efficiency of the algorithm are compared with the dynamic model of a high pressure rotor bearing system of a gas turbine.The comprehensive analysis shows that the Newmark-? method has more advantages in solving high-dimensional nonlinear rotor dynamic responses.Finally,the natural characteristic of the high pressure rotor system and the coupled dual rotor system are numerically calculated,get the critical speed through the Campbell diagram,the vibration shape diagram,the bifurcation diagram,the axis orbit diagram,the spectrogram and the Poincare map are drawn.The influence of rotor speed,the unbalance value,the ritual clearance of rolling bearing to the nonlinear dynamic response of the high pressure rotor system are analyzed.Analyze the influence of co-rotating and counter-rotating of the rotors,the speed ratio of the high pressure rotor and low pressure rotor,the stiffness of inter-shaft bearing to the natural characteristic of the dynamic model of coupled dual rotor-combined bearing system.The influence of rotor speed,the position of unbalance mass and the inter-shaft bearing to the nonlinear dynamic response are analyzed.And,in this paper,the influence of abrupt imbalance to the response of the coupled dual-rotor system is investigated.