Study On Vibration Suppression Of Complex Dual-rotor System Of Aero-engine

Numerous studies have shown that abnormal vibration in aircraft engines is one of the main causes of mechanical failures and even fatalities in aircraft.In the pursuit of high thrust-to-weight ratios and fuel efficiency,modern aero-engine structures tend to become more complex.The flexible design of high and low pressure rotors,the use of elastic rings and rolling bearings between rotors and between the rotor and the magazine,make the engine have a considerable number of orders and complex inherent properties of vibration,the actual appearance of a wide range of resonance intervals and complex response behaviour,which brings great difficulty to the forward design of aircraft engines.Therefore,it is of practical significance and research value to carry out vibration suppression analysis of complex dual-rotor systems of aero-engine.Taking an actual aero-engine rotor system as the research object,this thesis carries out the fine modeling and dimensionality reduction simplification of complex disc-drum-shaft dual-rotor system,the modeling of the extruded oil film damper dual-rotor system,the nonlinear dynamic solving algorithm,the visual map analysis method,and the multi-parameter nonlinear steady-state response analysis from the perspective of forward dynamic analysis.The specific research tasks are as follows:First of all,based on the knowledge of rotor dynamics and computational analysis methods,the solid engine is used as the reference prototype to establish a three-dimensional refined model with modeling software The fixed-interface modal synthesis method is introduced and used to reduce the dimension of the high-precision model.The comparison of the natural vibration characteristics of the dual-rotor is carried out through simulation analysis,which verifies the efficiency of the reduced-dimension model.Solve the critical speed and compare the characteristics of the critical speed of different orders,analyze the impact of the change of the bearing stiffness of the high and low pressure rotors on the critical speed,and find that the stiffness of the right support of the low pressure rotor has the greatest impact on the critical speed,Secondly,the dual-rotor model of squeeze film damper is established,and the oil film force model is built based on Reynolds equation and short bearing theory,and the vibration response characteristics of the dual-rotor system and the damping effect of the extruded oil film damper on the resonance region of the dual-rotor system are investigated by the Newmark-β method considering the oil film force,according to the simulation calculation,the relationship between the parameters of the high and low pressure rotor system and the vibration is carefully studied.It is found that the squeeze film damper has obvious effect on vibration suppression of the system,and reasonable increase of the support stiffness and damping coefficient of the system can improve the anti-vibration ability of the system.Finally,the influence of the intrinsic parameters of the squeeze film damper,such as oil viscosity,oil film clearance and static eccentricity,on the vibration characteristics of the system is studied,and the vibration response of the dual-rotor system caused by the number and different installation positions of the squeeze film damper is emphatically analyzed.It is found that the vibration reduction effect of multiple dampers in combination is more obvious than that of single damper,The vibration reduction effect is better when the installation position is reasonably selected,such as the position with the largest bearing radius.A series of studies in this thesis provide a reference for vibration suppression using extruded oil film dampers,and provide a feasible technical solution for the dynamic design of a class of complex structural rotor systems represented by aero-engine.