| Rotating machinery has been widely used in military and civilian equipment such as aviation,aerospace,power etc.Rotor system is an important component of rotating machinery,thus the overall machine whether operating reliably directly depends on which the working performance of rotor system is good or bad.With the rapid development of aero-engine manufacturing technology,the dual-rotor system has been employed in part of turbofan engine,it can reduce casing load to some exent and improve the working pefromance of aircraft compared with single-rotor system.In general,aero-engine always run in a terrible environment included high rotational speed,high temperature and high pressure and so on,the dual-rotor system will be subjected to a variety of coupling excitation sources.Therefore,it is of great significance in the research on natural characteristics,rub-impact fault and looseness fault dynamic characteristics of dual-rotor system.In this paper,taking the counter-rotation dual-rotor as the research object,based on finite element method,the dynamic model of dual rotor-casing coupling support system is established,then the dynamic characteristics is analyzed when dual rotor-casing system is operating with unbalance fault,point rub-impact,local rub-impact fault and looseness fault respectively,and the effects of main working system response on parameters are deeply discussed.The main research contents in this paper are as follows:(1)Taking the dual rotor-casing coupling support system as a research object,considering the Gyroscopic effect of inner and outer rotors,the system dynamic model is established used FEM,and the accuracy and reliability of the model are verified by comparing the natural characteristics and Campbell with Matlab and ANSYS results.(2)The basic theroy of rotor-stator rub-impact and numerical algorithm are introduced,then the point rub-impact model of dual rotor-casing coupling support system is established,and the effectiveness and feasibility of the model are verified by comparing the unbalance and rubbing responses with Matlab and ANSYS results;in addition,the effects of different parameters such as rotational speed,speed ratio,rub-impact stiffness and rub-impact gap on point rub-impact response are discussed.(3)The local rub-impact dynamic model of dual rotor-casing coupling support system is established,the effects of different parameters such as rotational speed,speed ratio,rub-impact stiffness and amount of unbalance on local rub-impact response are analyzed by bifurcation diagram,shaft centerline orbit,time-domain graph and three-dimensional spectrum.(4)The dynamic model of dual rotor-casing coupling support system with looseness rub-impact fault is established,the vibration characteristics have been made a comprehensive analysis with different rotational speed,looseness stiffness and looseness gap under the cases of looseness fault and looseness-rub-impact coupling fault.It can be found that the coupling fault is far from a linear superposition of single fault,and the system response will generate some coupling fault features. |
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