Analysis Of Dynamic Characteristics Of A Dual-rotor Aero-engine Subjected To Maneuvering Conditions

Maneuverability is an important criterion to measure the performance of the aircraft,maneuvering flight can have a greater impact on the stable operation of the aero engine rotor system,its dynamic response characteristics have many differences compared to the system fixed on the ground.In this paper,a coupled dual-rotor aero engine is selected as the research object.The dynamics of the dual-rotor system are studied by using numerical simulation and experimental methods under fixed base and maneuvering flight conditions.The main work and conclusions are as follows:1.The current research of rotor dynamics with no fault and rub-impact under fixed base and maneuvering flight is reviewed,the related theoretical knowledge and testing technology are introduced.2.A dynamic model of a dual-rotor-ball bearing coupling system under maneuvering flight is established by using Lagrange's equation,the coupling effect of the intershaft bearing and the influence of gyroscopic moments are considered in this model,while Runge-Kutta numerical method is applied to solve the equation under leaping and rolling flight.The result shows the form of rotor's movement turns into quasi-period and chaos response when suffering maneuvering flight.The vibration amplitude increases and more frequencies appear when the maneuvering flight speed increases,and the axial equilibrium position shifts as well,the sub-harmonic and super-harmonic resonance occurs.By comparing with the experimental results,the correctness of dynamic model is verified.3.Considering the effect of rub-impact between the outer rotor and casing on the basis of dynamic model of dual-rotor-ball bearing coupling system under maneuvering flight,the motion law of rotors with rub-impact fault is studied.The result shows that: when suffering maneuvering flight,a substantial increase in the rotor's vibration amplitude can cause rub-impact fault,axis orbits changes greatly and axial equilibrium positions reciprocate between different contact points.The rub-impact fault speed region increases,the degree of rub-impact fault aggravated,and the speed of bifurcation point delays.Some larger proportion frequency division and frequency doubling appears,the sub-harmonic and super-harmonic resonance becomes seriously.Experimental results are in good agreement with the numerical simulation results,the correctness of conclusions in this paper are verified.The designed and manufactured rub-impact structure of the dual-rotor system is of great significance in the field of aero engine rotor dynamics with rub-impact fault experiment,the laws and features drawn from theory analysis and experiments of dual-rotors under maneuvering flight can provide a reference for the relevant aspects of researchers,it also makes up the shortcomings of long time spent,waste of resources in real machine experiments.The results of this study have a reference value for the design and fault diagnosis of aero engine rotor systems.