Nonlinear Vibration Characteristics Of Dual-Rotor System In Maneuvering Flight Environment

The vibration of dual-rotor system in the maneuvering flight environment always threatens its safe operation,so it is necessary to study the nonlinear vibration of the dual-rotor system in the maneuvering flight environment.In this paper,the dynamic model of dual-rotor system in the maneuvering flight environment is established.Taking the horizontal hovering maneuvering flight condition as an example,the primary resonance and combination resonance characteristics of dual-rotor system in the maneuvering flight environment are studied by combining numerical and analytical methods.The main work is as follows:The dynamic model of a dual-rotor system in maneuvering flight environment is established.Regarding the dual-rotor system with inter-shaft bearing in the maneuvering flight environment as research object,taking the maneuvering flight environment,double frequency unbalanced excitation of high and low pressure rotor,nonlinear restoring force of inter-shaft bearing and inter-shaft bearing clearance,etc into consideration,the dynamic model of dual-rotor system is established by using Lagrange equation.The dynamic equations of the rotor system are calculated by the combination of analytical and numerical methods..On the one hand,the applicability and correctness of the model are verified,on the other hand,Typical nonlinear vibration phenomena such as bistability,sudden vibration jump and combination resonance are found.The primary resonance characteristics of dual-rotor system in maneuvering flight environment is studied.Taking the horizontal hovering maneuver as an example,the main resonance characteristics of the rotor system,such as bistability and sudden vibration jump are discussed by combining analytical and numerical methods.The influence law of the maneuver load on the primary resonance characteristics of the dual-rotor system is revealed.The influence law of the key parameters of the rotor system on the primary resonance characteristics of the system under the action of the maneuver load is analyzed.It is found that there is “enhanced stiffness” effects on the dual-rotor system caused by the horizontal circling maneuver load.The combination resonance of dual-rotor system in maneuvering flight environment is studied.By combining analytical and numerical methods,it is found that there are many kinds of combined resonance in the rotor system.By decomposing the response according to the frequency component,the mechanism of the combination resonance is analyzed,and the influence of the key parameters of the system on the combined resonance is discussed.It is found that the combination resonance of dual-rotor system is mainly determined by the clearance between the intermediate bearings of the rotor system,and there is also an obvious vibration jump phenomenon in the combined resonance region of the rotor system.The research results of this paper have some reference value for further understanding the primary resonance and combination resonance characteristics of the dual rotor engine system in maneuvering flight environment.