| The gas turbine engine is widely used as strategic equipment in modern industry.The rod fastening rotor-bearing system is one of the key components in the gas turbine engine,which plays important roles in energy conversion and power transmission.The operational stability of the rod fastening rotor-bearing system determines the safety performance of the engines.Therefore,the core technology research related to the effective lubrication and dynamic design of the rod fastening rotor-bearing system becomes one of the hot issues in current years.In this dissertation,in order to meet the requirements of the high-efficiency and high-reliability rod fastening of rotor-bearing system in gas turbine engines,the rapid solution method for the tribological characteristics of supported bearing and the solution method of nonlinear dynamic responses for the rod fastening rotor are studied.These studies can provide valuable basic theoretical reference for the dynamics design of the high-performance advanced gas turbine engines.The main contents are listed as follows:(1)For hydrodynamic sliding bearing taken as supporting part of the rod fastening rotor,the oil film pressure distribution is expressed as the sum of special solution and general solution using the method of separation of variables and Sturm-Liouville theory.The expressions of special solutions and general solutions are the algebraic combination form of axial separation function and circumferential separation function respectively.Based on downstream Reynolds boundary condition or rupture boundary condition in actuality,an approximate analytical solution for the nonlinear oil film force of the bearing is presented.On this basis,the influence of structure parameters and operating parameters of the bearing on the oil film rupture boundary and nonlinear oil film force is studied.(2)Based on the downstream Reynolds boundary condition,an approximate analytical solution of nonlinear oil film force of finite length hydrodynamic slide bearing with upstream and downstream boundary condition is presented with taking the oil supply and reformulation boundary condition into further consideration.In the solution,the oil film pressure is written as the product of axial separation function and circumferential separation function according to the separation of variables method.The axial and circumferential separation functions are analytically expressed using the variation principle and the infinite length bearing model.On this basis,the cavitation zone and oil film pressure are studied for various structure parameters and operating parameters of the bearing.(3)For the circumferential rod fastening rotor,with consideration of the contact effect and gyro effect of the disks,the dynamics equation is developed by using Lagrange dynamics equation and analyzing the potential energy and kinetic energy.In order to solve the dynamics equation,an improved high-precision Newmark method is presented,which can compensate the cumulative error and make the results satisfy the motion constraints and dynamic balance equation simultaneously.Furthermore,an effective solution method is presented to analyze the stability and bifurcation behaviors of the periodic solution of nonlinear rotor system by combining the predictor-correction mechanism,Floquet theory and Wilson-0 method.(4)For the fixed-tilting pad bearing-rod fastening rotor system,with consideration of the rupture condition of oil film,the oil film force of the fixed-tilting pad bearing is calculated based on the database of nonlinear oil film force of single pad,which is developed by employing the Castelli method to solve the Reynolds equation.On this basis,the dynamics behaviors of the system are analyzed,and the influence of tilting pad moment of inertia,preload,and pivot ratio on the dynamics behaviors of rotor is investigated.Meanwhile,the dynamics behaviors of rod fastening rotor is studied by considering the gyro effect of disks,and the influences of the gyro effect of disks on the motion of the rod fastening rotor are also analyzed.(5)For the fixed-tilting pad bearing,a thermo-elastic hydrodynamic lubrication model is developed with consideration of oil film thermal effect and elastic deformation of bearing under heavy load condition.Moreover,because the tilting-pad can rotate around the pivot,the friction between spherical pivot and tilting-pad is modeled.On this basis,the influence of pivot friction,oil film thermal effect,and elastic deformation on the lubrication characteristics of fixed-tilting pad bearing is investigated.In general,dynamics behaviors of the rod fastening rotor-bearing system and its related aspects are studied in more detail.The results can be used to direct the design of related rod-fastening rotor system. |
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