Study On Dynamic Characteristics Of Coupled Double Rotor And Composite Support System

At present,the gas turbine is moving in the direction of high power,high speed and light weight,which makes the problem of shaft vibration become more and more prominent.In modern gas turbine,intermediary bearing is usually designed between the high and low rotor to couple them,thereby reducing transmission force component quantity,shorten the axial dimension of the rotor,so as to lighten the weight of the engine.However,due to the existence of the intermediate bearing,the mechanical connection between high and low pressure rotor increased,and vibration between the two rotors will affect each other.Therefore,the dual rotor system with an intermediate bearing is more complex and needs to be calculated and analyzed accurately.This paper aiming at coupled dual rotor system that has intermediate bearing of the aircraft engine,a coupled dual rotor bending vibration dynamic model was built up based on the Timoshenko beam model and finite element method,with the rigidity of the intermediate bearing considered.Considering inertial matrix,rigidity matrix and gyroscopic matrix of the coupled dual rotor,and using QR decomposition method,bending vibration critical speed and model of vibration of the system were computed,and the influence of the rigidity variation of the intermediate bearing on bending vibration critical speed and the mode of vibration of the dual rotor system were analyzed;By means of nonlinear system response(the graph in time domain,frequency spectrum,Poincare map,orbit,frequency response diagrams,bifurcation diagram),the first analysis of the coupled dual rotor-bearing system in separate high-pressure rotor system with nonlinear response phenomena is done;Then the coupled dual rotor system with nonlinear response analysis,analysis in non symmetrical support in the form of a coupled dual rotor system with gyroscopic effect and intermediary bearing nonlinear characteristics.The rolling ball bearing radial clearance,disk mass eccentricity,node position of the disk mass eccentricity force,oil viscosity,oil film clearance,the rotation direction of the high and low pressure rotor,high and low pressure rotor speed ratio,nonlinear characteristics of intermediate bearing are impotant factors in the coupling effect of dual rotor combined supporting system is shown by the analysis.