Vibration Analysis And Experiment Research On Misalignment Of A Three-point Supported Dual-Span Rotor System

The rotating machineries, such as aero-engine, turbine, compression engine, pumps, are widely used and playing important roles in the fields of industry production. Rotor system is a core part of rotating machinery. Once mechanical fault occurred, the vibration will do great harm to the normal operation of the system,even lead to disastrous accident. In the engineering industry, about60percent of the mechanical faults are related to misalignment. There are many factors leading acute vibration to the machinery. The misalignment of the rotor system may cause vibration, deflection of couplings,abrade of bearings,unsTableility of oil slick and bending transformation of shaft etc.which will do great harm to the sTableility of the system. Therefore, it is very important to study the mechanism and charateristic of misalignment to distinguish this kind of fault effectively and rapidly.In this paper the vibration characteristics of misaligned three-point supported dual-span rotor system are obtained by numerical simulation and experiment following the finite element method based on rotor dynamics.The main research contents of this paper are as following:(1) The basic theories of modeling by the rotor dynamic and finite element method are introduced, and modal analysis based on finite element method are also introduced.(2) The dynamic model and finite element model based on the three-point supported dual-span rotor test rig are esTablelished.The nature frequency, vibration mode and the critical speed of the three-point supported dual-span rotor system are calculated by MATLAB and ANSYS, and the correctness of the simulation model is proved by the comparison of the MATLAB and ANSYS results.(3) The dynamic model and finite element model of the unbalanced three-point supported dual-span rotor system are esTablelished.The unbalance exciting force is deduced. And the unbalance simulation analysis are processed under different rotating speed by finite element method. (4) The dynamic model and finite element model of the three-point supported dual-span rotor system with both unbalance and misalignment are esTablelished. The misalignment exciting force is deduced.The vibration responses are analyzed under different rotating speeds and different misalignment cases.(5) The test rig of three-point supported dual-span rotor system is set up, and the experiment research is done. Both the simulation results and the experimental results prove that the amplitudes of the misaligned rotor vary with rotating speeds and misalignment angles, and the center orbits of the misaligned rotor change into ellipses with the increase of misalignment, together with double harmonic responses.