Research Of Similar Dynamic Characteristics Of Rotor System

Rotor system is a crucial part of rotating machinery whose dynamic characteristics are influenced by many complicated factors. There are mainly two methods in theoretical analysis of rotor system, which are analytical method and model simulation method. However, analytical method needs to accept a variety of assumptions and model simulation method needs to simplify the boundary conditions. Therefore, it’s not enough only using theoretical analysis without physical tests in accurately resolving dynamic problem of rotor system. Compared with tests using prototype, it’s more practical and targeted using model in tests. Meanwhile, control the main influencing factors is possible in this way. It’s possible to predict the dynamic characteristics of prototype system according to the test results of model system on the basis of researching the similar dynamic characteristics of rotor system. Tests using model system in fault condition even can reproduce the faults of prototype system. Therefore, researching on dynamic similarity and similarity design method of the rotor system is especially important.In order to study the similar dynamic characteristics of rotor system, the similarity criterion and the similarity relation are derived from dynamics equations of rotor system rotor using dimensional analysis method and equation analysis method. The geometrically similar theory and non-geometric similarity theory of rotor system are validated by simulation calculations using finite element method. The prediction accuracy of the geometrically similar model influenced by bearing parameters is studied at the same time. Similarity design method and processes of the rotor system are also summarized in this paper. The controllability of the similarity design method is theoretically confirmed through comparison analysis and simulation calculation verification of the typical similarity designing scheme for the test factors. The similarity design method in this paper, which can reduce the critical speed of the model system, completely shows how to get a similar model of rotor system from its actual prototype. Comparing the critical speed of prototype and model of rotor system, which is calculated by finite element method, the feasibility of similarity design is verified from the perspective of the simulation calculation. Finally, based on the vibration test of the test rig got from the real engine by similar design, the feasibility of similarity design is verified again from the perspective of the model test, when comparing the vibration domain diagram and the frequency spectra diagram in normal and unbalanced working condition.