Coupled Dynamical Analytical Method Research On Internal And External Dual-Rotor System For Aeroengine

At present,dual-rotor structure is widely used in aero-engines.In this structure,lowpressure rotor and high-pressure rotor sleeve together.The vibration of rotor system caused by the blade discs,the supportings,the unbalance of rotor and the misalignment of supportings,is the main source of aeroengine vibration fault.The study are insufficiency on inherent characteristics,unbalanced vibration response of the internal and external dual rotor aeroengine,coupling of unbalanced vibration between two rotors.Combining theory,simulation and experiments is the main method to study the vibration characteristics of aeroengine.By building a simplified test-bed,the influence of many interference factors in aeroengine can be eliminated and the basic vibration characteristics of aeroengine can be analyzed.However,there are few test-beds for studying the vibration characteristics of aero-engine dual-rotor at present,as well as the study on basic vibration characteristics.Aiming at the internal and external dual rotor system of aeroengine,vibration characteristics analysis of aero-engine dual-rotor system was carried out.Based on the dual rotor system of aeroengine,Introducing the sleeve coupling and intermediate bearing,aeroengine dual-rotor system model was built according to the principle of equivalent mass and equivalent moment of inertia.The inherent characteristics of dual-rotor system was analyzed.Based on New-mark method,considering the interaction between two rotors,the unbalanced vibration response of internal and external dual-rotor system is analyzed,as well as unbalanced vibration response of dual rotor systems at different measuring points.And then,the incentive mechanism under the condition of supportings misalignment is deeply analyzed.On this basis,the vibration characteristics of dual-rotor systems are analyzed.Finally,a four-disk fivesupportings dual-rotor model test-bed was built to verificate of theoretical analysis and numerical simulation.The analysis results show that when the unbalance exists only on high-pressure rotor or low-pressure rotor,vibration response of rotor system is single-frequency vibration and the orbit of axle center is a regular circle.If unbalanced mass exists on both inner rotor and outer rotor,the vibration of the rotor system is a double-frequency vibration and the axis center trajectory is complex.In addition,the closer measuring point is to the intermediate supporting,the more obvious the coupling effect is.The closer the measuring point is to the location of unbalanced mass,the more sensitive to the unbalanced mass the measuring point is.The second harmonic frequency vibration will occur in supporting misalignment condition.The second-harmonic amplitude of the vibration response is quadratic to the supporting’s misalignment,and has a linear relationship with load torque of rotor,no relationship with unbalanced mass.The firstharmonic magnitude has nothing to do with the misalignment of supporting and the load torque of rotor.In this paper,the inherent characteristics,unbalanced vibration characteristics and supporting misalignment of dualrotor system are discussed.Research work on vibration characteristics has been carried out.The inherent characteristics of the dual-rotor system,the vibration response under unbalanced conditon and misaligned supportings are analyzed.The research conclusion has important value for vibration prediction,evaluation and control of aeroengine internal and external dual rotor system unbalance and misaligned supporting faults.