Dynamic Analysis Of Typical Rotor Systems With The Transfer Matrix Method For Multibody Systems

During the operation of the aircraft engine rotor,vibration problems are often very significant,and which affects the reliability and safety of the aircraft.The unbalanced excitation caused by the unbalanced mass of the rotor is a typical and inevitable source of excitation to the system.Therefore,during the process of design,calculating the critical speed and analyzing the unbalanced vibration response characteristics of low-pressure and high-pressure are regarded as fundamental scientific issues,and related research has important engineering value.However,the aircraft engine rotor system is a high-dimension complex rigid-flexible coupling mechanical system.It is very complicated to establish the dynamical model.Based on the practical engineering problems,it is of great significance to discuss the modeling formalisms and rapid computational methods of the aircraft engine rotor system.The transfer matrix method for multibody systems,a dynamical simulation method for multibody systems,has the advantages as follows: no need to establish the overall global kinetic equations of system,high degree of formalisms and high computational efficiency.In this paper,the dynamical models of the aircraft engine dual-rotor system,branched rotor system and rigidly supported multi-span rotor system are established based on the transfer matrix method for multibody systems.Compared with the critical speed calculated by the overall transfer matrix method and the typical transfer matrix method,it shows that the transfer matrix method for multibody systems has its unique advantages on rotor dynamical modeling.It can be found that:(1)for the overall modeling,the availability of the rotor dynamics modeling based on the transfer matrix method for multibody systems is verified by comparing with the overall transfer matrix method and the analytical solution,and it is further found that the transfer matrix method for multibody systems has high computation accuracy when calculating the critical speed of the aircraft engine dual-rotor system.(2)For typical rotor structures,the rotor system with branch and the multi-span rotor system with rigid support,the transfer matrix method can also gain the critical speed of the system.When the structures of the rotor system with branch and the multispan rotor system with rigid support are changed,the transfer matrix of the branch point and the transfer matrix of the point of rigid support have to be re-derived.The transfer matrices established by the transfer matrix method for multibody systems does not need to be re-derived,and the programming is higher than the transfer matrix method.(3)For tracing the solution of dynamical response,the unbalanced response dynamical models of the multi-span rotor system with rigid support and the aircraft engine dual-rotor system are established.Furtherly,we obtain the critical speed under the excitation of the low-pressure rotor or the high-pressure rotor,and analyze unbalanced response of the front and rear disks of the high-pressure and low-pressure rotor when unbalanced mass on front or rear disks of the high-pressure rotor or low-pressure rotor.In conclusion,applying the theory of rotor dynamics and transfer matrix method for multibody systems to develop complex rotor system dynamics modeling,analyze dynamical response and develop rapid simulation software has certain basic theory significance.