| Rotor-support system is an integral part of large rotating machinery such as aeroengine,whose vibration characteristics have a great influence on the normal operation of the aeroengine.Aero-engine mostly adopts dual rotor-support system.The research method of vibration characteristics of the dual rotor-support system besides theoretical analysis and numerical simulation,also requires experimental verification.Considering the economy and the difficulty of testing,the dynamic characteristics of aeroengine are usually tested by component-level tester in engineering practice.The component-level tester ignores the coupling between the components in the actual system,and the dynamic characteristics measured in the test cannot truly reflect the dynamic characteristics of the actual system.High-pressure rotor system is the core component of the dual-rotor system.It is coupled to the low-pressure rotor through the inter-shaft bearing,and the two rotor systems are mutually excited and coupled to each other.When the high-pressure rotor system is used as a component-level tester for test and research,it is an urgent engineering problem to ensure that the measured dynamic characteristics are similar to those exhibited in the dual-rotor system.Based on the dynamic characteristics of the high-pressure rotor in the dual-rotor system,the dynamic similarity model of the component level high-pressure rotor support system was designed,and a software was developed based on the relevant research in this paper.The main contents of this paper are as follows:(1)Based on the finite element method,the linear dynamic model of the coupled dual rotor-support system and the single high-pressure rotor support system were established,In addition,the nonlinear dynamic model of two systems considering the nonlinear force of bearing were established.The natural characteristics of the two rotor systems were compared and calculated by the modal analysis method,and the correctness of the modeling and modal solution method were verified by the test.The dynamic response of the two rotor systems were analyzed by Newmark-β method based on matrix reduction.The correctness of the numerical method was proved by literature comparison and simulation comparison.The difference between the dynamic characteristics of the two rotor systems caused by the coupling action of the inter-shaft bearing was explained in detail.(2)Based on the direct derivation method,the sensitivity formulas of undamped eigenvalues and eigenvectors of rotor-support system to parameters of turntable,shaft and bearing support were derived.On the basis of sensitivity analysis,the structural dynamic modification method of rotor-support system was established.Combined with sensitivity analysis and structural dynamic modification technology,a continuous sensitivity analysis method of rotor system based on iterative solution was proposed,and the dynamic similarity model of high-pressure rotor support system was designed by using this method.(3)According to the fact that the inter-shaft bearing is placed at the modal node of the rotor system,the coupling degree of the vibration between the rotor systems can be reduced.The position of the inter-shaft bearing was optimized to the modal node of the rotor by adjusting the support stiffness and modifying the mode shapes.It was proved by an example that the system after optimizing the inter-shaft bearing position can realize the dynamic similar model design of the component-level high-pressure rotor support system.(4)Based on the user interface editing tool GUI of MATLAB,combined with the related research content of this paper,a software RDSMD for dynamic similar model design of rotorsupport system was developed.The software can be used to calculate and analyze the dynamic characteristics of rotor-support system based on finite element method,and to realize the similar design of rotor-support system dynamic characteristics based on sensitivity analysis and structural dynamic modification technology. |
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