| Aeroengine is usually used as the power sources of the aircraft,the performance of it have great influence on the people's livelihood and the national security.Under the high load and high efficiency,large vibration amplitude,abrupt vibration and slow-varying vibration appear on this kind of complex rotating machine because of the requirement of high processing accuracy as well as the features of structural complexity and harsh working condition,which greatly reduces the reliability and operation life of the aeroenging.The vibration characteristics of the rotor system is related to the combined support,a number of studies have shown that the nonlinear stiffness and damp tend to induce the typical nonlinear vibration such as the superharmonic,subharmonic,chaotic,bistable state and jumping phenomenon,which is not beneficial to the stability and the fatigue life of the aeroengine.For this reason,the investigation into the force characteristics of the combined support as well as the response characteristics of the combined support-rotor system have become an important factor in the aeroengine development.This model considering the forces characteristics of the combined support containing the squeeze film damper,rolling bearing and the squirrel cage elastic support in the aeroengine was established,a modified numerical integration method and the IHB method were adopted to solve the differential equation of the finite element model as well as the lumped mass model of the combined support at different operational conditions.In this way the nonlinear characteristics and the vibration response characteristics with the unbalance fault as well as the rubbing fault of the combined support were summarized to offer the theoretical analysis experience of predicting the abnormal vibration in the aeroengine,accordingly the combined support can be designed purposefully and optimally.The research focus on the following 4 points:(1)Based on the coupling relation among the internal components of the combined support,a analytic model of the combined support was established.The frequency response curve of the combined support subjected to the unbalance force was traced through the IHB method and the arc-length method,and the bistable phenomenon with mulple solution was analyzed in the frequency domain and time domain.The response characteristics of the combined support was compared with the response of the single support included in the combined support,and the differences and similarities between the single support and the combined support were compared and summarized.(2)Based on the finite element method and lumped mass model,the analytic model of the combined support-high pressure rotor in the aero engine was established.The effect of the combined support on the vibration characteristics and stability of the high pressure rotor at different locations was discussed,and the parameter intervals of the nonsynchronous response were classified and summed up.The results show that there is the close relationship between the motion state of the shaft and varying pattern of the support force at the same place.(3)Based on the dual rotor structure in the turbofan engine,a finite element simulating the mass distribution,support location,shaft size in the real aeroengine was established.The differences of the different locations of the rotor for the different speed ratio were analyzed.The nonlinearity of the clearance,the amount of unbalance and their locations on the vibration response of the rotor was summarized.(4)Considering the robbing fault between the rotor blade and the stator casing in the aeroengine,the nonlinear force model of the combined support and the rubbing force was adopted to investigate the response characteristics in the time domain and the frequency domain,and the effect of the rubbing parameters on the vibration performance of the high pressure rotor,explaining the reason of the abnormal nonlinear vibration phenomenon that rubbing location and the location of the abrupt vibration were not consistent. |
PDF Full Text Request