Vibration Reduction Characteristics Analysis Of Static Eccentric Squeeze Film Damper-rotor System

The main function of the squeeze film damper is to reduce the bearing outside force and the rotor amplitude of resonance.Because of its simple structure,light weight,small size and great vibration damping performance,it has been widely used in modern aircraft engines.The rotor system as the basic structure of the engine,its unbalanced characteristics and vibration in the critical speed range is the main cause of engine's vibration,therefore the application of squeeze film in aero engine has become a trend,Affected by the processing technology,weight of the structure,structure design,assembly process,there is static eccentricity in the squeeze film damper,which makes a difference on the stable operation of the system.Above all,the theoretical research on vibration characteristics of rotor system with squeeze film damper has an important engineering value and practical significance.This thesis researches on dynamic behaviors of rotor system with squeeze film damper,the specific contents are as follows:Based on the squeeze film damper single roto system model,analyzes the vibration-reducing mechanism of squeeze film damper.It is found that squeeze film damper only suppresses the amplitudes of systematic resonance zone,but has less effect outside the resonance zone.In the analysis of static eccentricity on the system damping characteristics,it is found that the damping performance of squeeze film damper hardly gets effected light small static eccentricity.However,the damping performance of squeeze film damper enhances as the static eccentricity increases.At the same time,larges eccentricity narrow down the motion range of the proton,which forces the inner ring go out of the rang of clearance of film.As a result,a series of unfavorable phenomenon come into being,such as rub-impact and jump.Study on the dynamic characteristics of dual rotor system with squeeze film damper and intermediate bearing,high and low pressure rotor disc found vibration response is consistent with that of the more obvious,high and low pressures rotation frequencies stimulate successively first order and second order resonance;combination resonance is found taking place in the system through spectral analysis.Besides,it analyzes the vibration reducing characteristics of squeeze film damper in the system and discusses the effect of the number of rolling elements,damping factor and unbalance factor on the system.Low pressure rotor shows different modes of vibration response under different parameters.Finally the motion of the static eccentricity squeeze film damper-inter-shaft double rotors systematic model considering vertical static eccentricity is established.And it summarizes the changes of systematic self-energy and nonlinear force.Compared with rotor system,it can keep original dynamic characteristics under light static eccentricity.However,the vibration of system becomes more sensitive under strong static eccentricity,and it is easy to generate rub-impact and snap back,which forces the damper fail.On the analysis of lubricating oil viscosity and radial internal clearance on systematic vibration characteristics,it is found that strong lubricating oil viscosity can improve the anti-vibration performance.Besides,the increase of radical internal clearance will reduce the contact stiffness between raceway and ball within the bearing,which can promotes the jumping phenomenon of the system.