Research On The Dynamic Characteristics Of Flexible Disk-drum Coupling Structure

Disk-drum rotor system is widely used in many fields of engineering because of its great bending rigidity as well as the ability to withstand large centrifugal loads,especially in the high-pressure compressor of modern turbofan engines.As the common structure in aero engines,drum is often subject to huge inertia forces,gas forces,and complex vibration loads.So unreasonable design may lead to specific parts vibrate violently,which can cause parts damage and then affect the normal operation of the engine.Therefore,in order to analyses dynamic characteristics of the disk-drum coupling system,and grasps its complex regulation.It is of great important to establish reasonable mathematical model of the coupling system.A dynamic model of rotating disk-drum coupling system was developed in this dissertation.Base on the elasticity theory and rotor dynamics.A differential equation of rotating flexible disk and elastic supported drum coupling system was deduced by using energy method.According to the theory of mechanical vibration,the dynamic characteristics of coupling system are studied.Moreover,vibration responses of coupling system rubbing contact with stator are derived.The mainly research in this dissertation are listed as follows.Firstly,considering the centrifugal stiffening effect,Coriolis' effect and hoop initial stress,the governing differential equation of rotating rigidly disk-drum coupling structure was derived by using Donnell's non-linear thin cylindrical shell theory.The impact of the coupling effect between drum and disk on its natural frequencies is investigated.Meanwhile,the nonlinear amplitude frequency characteristics of drum is analysed by variation of different parameters.The results show that the nonlinear shell theory should be adopted for the rotating drum with stubby and thin-walled characteristics.Secondly,dynamic model of rotating flexible disk and elastic supported drum coupling system is established.The governing equations of coupling system are derived by using discretization method and lagrange's equations.The validation of the dynamic model is examined by previous literature.Thus,the dynamic characteristics of coupling system are studied,and vibration respond of coupling system under the harmonic excitation is analysed.The results show that the coupling effect between flexible disk and drum has signigicant impact on the dynamic characteristics and response of coupling system.Last,rubbing dynamic model of disk contact with stator and drum contact with stator are established.Dynamic responses of the rubbing dynamic model are studied by using numerical calculations.The effect regulation of parameters(i.e.contact stiffness,clearance,friction coefficient,rotating speed)are discussed.The results show that drum is more sensitive to rubbing.