Dynamics of a Three Level Rotor System Using Solid Elements

Abstract

This paper discusses the interaction of support structures on the dynamics of a dual rotor system. The system considered is a dual rotor, supported on flexible bearings, which are in turn mounted in a flexible casing. ANSYS® is used for modeling and meshing the dual rotors and the casing. The rotors are modeled using solid elements. The bearings are simulated as springs, wherein the direct and cross coupled stiffness and damping coefficients are applied. The casing is also modeled and meshed in ANSYS® using solid elements. Different spin speeds are applied to the dual rotor system. The casing is also rotated at a zero spin speed. The Stress stiffening and spin softening options are also set on for the dual rotor system. The system natural frequencies are obtained for different spin speeds and the Campbell diagram of the system is plotted. The critical speeds due to per revolution excitations are then extracted from the Campbell diagram.