4. Nonlinear and Linear Phenomenon Investigation of Coupled Vibration of a Multi-disc Rotor Based on Multi-mistuned Blades Length or Multi-disordered Staggle Angle Blades

According to the previous researches in the authors’ Lab, some papers only used assumed mode (AM) method to investigate the rotor system with mono-flexible-disk and mono-blade that have mistuned or disordered. Calling for special attention to this work is that there are two methods adopted together, including the FEM and the assumed mode (AM) method. This chapter refined the disk-transverse, blade-bending and shaft-torsion coupling vibrations phenomenon of a multi-disc system with multi-mistune or disorder blades. The first one is primary, and the others play subsidiary roles. Some beneficial and interesting results are shown in this chapter. First of all, the authors used the AMM and FEM (ANSYS) to study and compare the change regulations of the natural frequencies (NF) and mode shapes (MS) in the rotor system. The second is that the authors pointed out how multi mistune or disorder blades affect the coupling vibration phenomenon of the system. Numerical calculation results also showed that the number of the mistune or disorder blades as well as the symmetry of the mistune or disorder blades would affect the natural frequencies. Above all, the author give the reasons why the finite element method is not suitable for analyzing these complex and changeable phenomenon of coupling vibration in a multi-disc system with multimistune or disorder blades. Lastly, the rotation effect is also explored in this chapter, and the authors found that mistuned effect would become complex and unstable.