Multi-level Modeling Method for Vibration Analysis of Compressor Rotating

Compressor rotating blades are connected with the disk and subjected to complicated loads including aerodynamics, mechanical interactions and thermal effectiveness. In this paper, a novel multi-level modeling strategy based on finite element method (FEM) is proposed to calculate accurately the vibration responses and stresses of compressor rotating blades with the capacity of involving the efforts of faults of rotor system. Firstly, a FE model of the compressor rotor system is established with a few of degrees of freedom, in which the fault-induced forces are introduced conveniently. The dynamic responses of the nodes corresponding to the disk and bearing are then calculated with directly numerical integration. Secondly, the blade-disk component is modeled based on assembling the FE models of each blade and the disk and the nodal response output from the above rotor system is regarded as displacement boundary condition of it. The nodal responses of the blade roots will be used as base excitation inputs in the next stage of the multi-level modeling method. Thirdly, a perfect model of a single blade is established. The boundary conditions include the contact stresses and displacements of the blade root, aerodynamic loads on the blade body and possible rubbing on the blade tip, etc. The vibrations and dynamic stresses of the blade are then calculated and used for designing and assessing its life prediction. An example in the last part of the paper illustrates the capacity of the above multi-level modeling and analyzing strategy.