Study On Vibration Characteristics Of Low-Pressure Rotor System Of Turbofan Engine

In recent years, considering national security and the long-term development of economy, More and more attention is attached to the research and development of aviation engine in our country. With the establishment of national science and technology major project "aeroengine and gas turbine", the country will integrate all aspects of resource in this field to seek a breakthrough. In a variety of aviation engine, turbofan engine is widely used because of high thrust, high efficiency, low fuel consumption and low noise. Low-pressure rotor system is an important part of the turbofan engine. It is directly related to the safe and stable operation of the whole machine. At present, the research on its vibration characteristics is far from enough.In this paper, the advanced turbofan engine is the research object, and the research work is carried out in view of the low-pressure rotor system with nonlinear coupling and statically indeterminate rotor structure. The main research contents and conclusions of this paper include:1. An expression for the circumferential contact gap of cylindrical contact surface is derived. Then the contact stiffness model of cylindrical contact surface is established. The influence of contact force, assembly clearance, cylinder contact length and surface roughness on the cylindrical contact stiffness is obtained by simulation, and is verified by the experiment. Research results show that:with the increase of contact force, the contact distance decreases and the contact stiffness increases.2. Based on the flexibility analysis, dynamics modeling method of complex rotor system is studied on. The analytical dynamic model of two degrees of freedom is obtained, and is verified by the finite element simulation and experiment.3. Based on the finite element method with few degrees of freedom, the dynamic characteristics of low-pressure rotor system of turbofan engine is studied.4. Vibration characteristic experiment rig of three-elastic-support rotor system with gear coupling is designed and built. The rig is aligned by the high precision laser alignment instrument.