Research On The Fault Of The Rubbing Rotor System With Thermal Bending

Thermal bending fault is one of the most common faults in rotating machinery. Generally it refers to bending deformation caused by different thermal expansion the metal which is due to the uneven temperature distribution in the circumferential direction of the rotor. And when rub and thermal bending both exist, it called frictional heat bending failure. Thermal bending fault would cause great damage to rotating machinery and its operation.This paper focuses on the analysis of frictional heat bending failure of rotor system that is based on thermal structure coupling analysis, nonlinear dynamics and dynamic finite element theory. Taking thermal bending failure and its associated failure(frictional heat bending)of aero engine rotor system failure as the research object, using the finite element method, considering the thermal effects, fluid effects, exposure deformation and other related factors, the model of thermal bending fault and frictional heat bending failure is built for following analysis. The work of this paper includes following aspects:First, the two kinds of finite element models which are called 2D,3D are used to establish the model of rotor system with thermal bending. By comparing the two methods, the results show that the accuracy of 2D thermal field analysis method is lower than 3D method but its computational efficiency is higher. It is suitable for the input of heat concentration and transient analysis. Three-dimensional thermal field analysis is in low calculation efficiency, but high precision. It is applied to the input of the heat dispersion and steady thermal field.Then,3D model of rotor system is created for thermal-structure coupling analysis. The influence which is caused by the change of the relevant factors of the thermal conductivity, heat convection coefficient on the temperature field of rotor system, thermal bending and the vibration characteristics caused by thermal bending is got. And the fault mechanism of thermal bending faults and friction thermal bending faults as well as the mutual coupling effect of friction and thermal bending faults are revealed.Finally, the finite element structure and three-dimensional thermal field coupling model of the rubbing rotor system with thermal bending is established. A new method called Incremental harmonic balance-Newton iteration method is presented. And the method is used for steady state response calculation and running stability analysis. The influence of the parameters such as rub-impact stiffness, rub-impact gap, friction coefficient etc. to the stability of the rotor system are quantitative analyzed using this method. Some rules of the stability of the friction thermal bending of the rotor system is mastered and a theoretical reference for the prevention of the friction thermal bending faults of rotating machinery is provided.