| The aero engine is known as the jewel in the crown of modern industry.As the key component of aero engine,it has been taken for granted that the dynamic modelling of shaft-disk-blade system is always the study hotspot.With the increase of thrust-to-weight ratio and the requirement for lightweight structure,the stiffness of the rotating shaft and disk structure reaches the same level.Therefore,the coupling characteristics between the components have to be considered to study the dynamic characteristic of shaft-disk-blade flexible system.Rubbing fault is another problem induced by the reduction of static rotor-stator gap.Most of the studies focus on the radial rubbing of the blade-casing system and the drum-stator blade structure.Nevertheless,the axial rubbing is usually neglected.In this paper,the dynamic modesl of stepped shaft-disk-blade system are established based on the finite element method and semi-analytical method considering the rubbing fault.Considering the effects of the rotor system flexibility,the coupling effect between multiple components,the gyroscopic effect,the centrifugal stiffening,and the spin softening.The main contents of this paper are listed as follows:(1)The dynamic model of the stepped-shaft-disk system is established based on the semi-analytical method and the model is verified by ANSYS simulation.The finite element and semi-analytical hybrid modelling method is proposed to simulate the dynamic characteristics of stepped shaft-disk system.The proposed hybrid modelling method has been verified by comparing the natural characteristics and response characteristics of the stepped shaft-disk system with the simulation results of commercial software ANSYS and the experimental results.Influence of the disk flexibility on the high-order vibration is also analysed.(2)Considering the axial rubbing fault,the radial rubbing and the coupling rubbing,the stepped shaft-rigid disk-casing rubbing system and the stepped shaft-flexible disk-casing rubbing system are studied.By extracting the axial-radial displacement and trajectory of the rubbing point at the outer edge of the disk and the casing,the influence of the disk flexibility and the coupling effect on the dynamic response of the shaft-disk system are analysed.(3)Based on the proposed finite element and semi-analytical hybrid modeling method,the dynamic model of stepped shaft-disk-blade system is established.The flexibility and coupling effect between various components is studied.The proposed model has been verified by comparing the natural characteristics and response characteristics with ANSYS and the experimental results.And the influence of gyroscopic effect,centrifugal stiffening and rotational softening on the dynamics characteristic of the coupling system are also analysed.(4)Considering the influence of the initial non-uniform clearance between the blade tip and the casing,the dynamic model of the stepped shaft-disk-blade rubbing system is established.The stiffness,static misalignment,initial clearance and installation angle are on the vibration responses of the system analysed.The dynamic characteristics of different blades during rubbing are compared by the time domain map,the trajectory waveform and the frequency speatra. |
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