Model Equivalent Reduction Method And Dynamic Analysis Of Rod-fastening Gas Turbine Rotor

Gas turbine is widely used in aviation,ships,power generation and other fields,and plays an extremely important role in national defense strategy and power energy.The actual working condition of gas turbine is usually formed by the coupling of high temperature,high pressure,high speed and gas-solid-heat multi-field.The structure of the rotor shafting of the gas turbine circumferential pull rod is complex,which is a complex dynamic system with strong coupling,high dimension and nonlinear.Based on the major special basic research project of aero engine and gas turbine: structural dynamics and vibration control of gas turbine rotor system,this paper conducts research on the contact effect of gas turbine circumferential tie rod rotor disc,model equivalent reduction treatment method and nonlinear dynamics analysis.Based on the analysis of the contact effect of the circumferential rod rotor disc,the expressions of the contact area,average contact pressure and contact load of the singlepeak microconvex body at each stage of contact were derived from the microscopic point of view,combining the Hertz contact theory and the boundary conditions of deformation and smoothness.Combining the single-peak contact theory and the probability distribution function of the height of the micro-convex body,the contact mechanics model of the macroscopic contact surface of the pull-rod rotor disk was obtained by integrating.The relationship between the contact area,the contact load,the normal contact stiffness and the average surface spacing of the three contact models was compared under different plasticity index conditions,and the variation rules of the parameters were summarized and the reasons were analyzed.According to the equivalent reduction method of gas turbine pull rod rotor model,the virtual material layer is introduced to take the contact effect into account,and the contact effect among the disks is reflected by controlling the parameter change of the virtual material layer.Based on the strain energy theory,the equivalent parameters of the rear shaft segment were determined and characterized mathematically.A program was developed to extract the strain energy and volume information of any shaft segment by using the finite element software.Finally,the equivalent reduction method of rotor model with complex cross-section and discontinuous structure is summarized.Considering the influence of axial temperature distribution on the elastic modulus and nonlinear oil film force,a finite element model of gas turbine shafting with axial temperature distribution was established based on the analysis of the dynamic characteristics of gas turbine shafting.By Newmark-beta numerical integral method for solving the nonlinear dynamic equation,the equivalent shaft section analyzes the rotor partition number,the axial temperature distribution in the parameter change on the rigid support rotor critical speed and the effect of prestressing force and pull rod size,unbalanced quality parameters on the nonlinear dynamic response of shaft system,adopting three dimensional spectrum,Poincare maps and bifurcation diagrams,axis path figure visual representation methods such as nonlinear dynamic behavior of the rotor.It is found that if the unbalance mass is increased and the preload is reduced within a certain range,the rotor will move steadily at a low speed and the oil film oscillation will be delayed.