Dynamic Characteristics Analysis Of The Dual Rotor-bearing System Of A Turbofan Aeroengine

The aeroengine is a kind of high speed and strong coupling thermal machine, and its core technology has been the target of the countries all over the world. Dual rotor structure is often used in aeroengine. The dynamic analysis of this structure is in the ascendant at home and abroad.This article improved the whole transfer matrix method, and use it on the dynamics analysis and simulation for the dual rotor-bearing system of a turbofan aeroengine.This atricle mainly research on the critical speed of the dual rotor-bearing system, bearing stiffness impact on critical speed, the vibration mode of the dual rotor-bearing system and unbalance response of the dual rotor-bearing system.The whole transfer matrix method is improved and the transfer matrix of the coupled large element is deduced. Through the improvement of the whole transfer matrix method, the thickness of the disk is included in the operation process, and the accuracy of the analysis is improved. On the single disc rotor examples included and not included in the two disc thickness of critical speed and each order vibration type. The results show that included in the disk thickness of whole transfer matrix method of calculation results are close to the simulation results, and errors are reduced significantly.The establishment of AЛ-31Ф engine successfully with engine dual rotor bearing system simplified model. Combined with the AЛ-31Ф engine overall structure drawing, were used to establish the calculation of high pressure and low pressure rotor simplified model and simplified structure model, and the recognition model the structure size parameters. Based on the coupling relationship between the two rotor bearing, the simplified model of the dual rotor bearing system of the engine is established.Analysis of critical speed AЛ-31Ф engine successfully with engine dual rotor bearing system and vibration modes. The critical speed of therotor bearing system is calculated and the influence of the change of the bearing stiffness on the critical speed of the rotor is studied. The critical speed calculation is compared with the normal operating speed of the engine.The results show that the critical speed of the engine is far from the engine’s normal working speed and has sufficient margin. Calculation of the vibration mode of the dual rotor bearing system.Unbalance response analysis of AЛ-31Ф engine successfully high, low pressure rotor. In the different positions of the high and low pressure rotor applied successively unbalance mass, were obtained under different conditions of high pressure and low pressure rotor vibration type, analysis unbalance mass is applied in different position each axis to withstand the impact of the degree of.Simulation verifies the dynamic characteristics of the dual rotor bearing system. Established dual rotor bearing system finite element model and high and low pressure rotor unit model, the dynamics characteristics of the dual rotor-bearing system through the finite element software is used to simulate and will comparison between simulation results and calculation results. The results show that simulation results show good agreement with calculated values.