Rotor Dynamics Design And Experimental Study On A High-speed Rotor Of A Small Turbofan Engine

Rotor is an important component of aero-engine,it is very important for safety and reliability of engine.With complex structure,the low-pressure rotor of a small-sized turbofan engine is a high speed flexible rotor which operates above the second bending critical speed,this brings rather difficulty for design and test of rotor dynamics.In order to solving a key technique during model development,based on the structure of the low-pressure rotor,the dynamics design and experiment researches of the dynamics of the representative low-pressure rotor are carried out systematically.First of all,the rotor support scheme and supporting structure of the typical flexible rotor system are analyzed.After absorting its characteristic and concept of structure design,the structural characteristics of low-pressure rotor of a small-sized turbofan engine are analyzed.The dynamic equation of the rotor is derived by the analytic method,and the dynamic design parameters are determined.Based on the structure of the low-pressure rotor,finite element analysis model of the rotor is set up.Based on the SAMCEF/ROTOR software,the dynamic characteristics of the rotor such as critical speeds,vibration shapes and stable unbalance responses,are systematically calculated and analyzed.The results show that the operating speed of the rotor is over the second critical speed,it is a typical high speed flexible rotor.The laws of the first three-stage critical speeds change with each supporting stiffness are revealed,the distribution of elastic support,the stiffness of elastic support and the layout of the fulcrum were determined.Finally,the rotor dynamic design was completed.Experiment investigations on dynamic characteristics of the rotor are implemented on a high speed rotating test rig,test scheme is proposed,the experiment verification of the first two-stage critical speeds is accomplished,and the first two-stage critical speeds are in good agreement with the calculation results.In this paper,the high speed dynamic balance research is carried out in the case of the failure of the low voltage rotor to cross the critical speed during the test.Research results in this paper has been applied in the design of low-presstue rotor of a small-sized turbofan engine,help to solve the key technology of model development,for the same type rotor structure design,vibration control and fault diagnosis to provide reference.