Dynamic Analysis Methods Of Mistuned Turbomachinery Impeller

Turbomachinery impeller is the core rotating component of centrifugal compressors. It works in complicated condition and its work status directly affects the safety of the whole compressor unit. With the advance of the design parameters for compressor, the mechanics character of turbomachinery impeller becomes more critical. In practice, there are small differences in the structural properties of individual blades, due to manufacturing and material tolerances or in-service degradation, which are referred to as blade mistuning. The inevitable mistuning increases the complexity of dynamic design for turbomachinery impeller.This thesis studies the dynamic analysis methods of mistuned turbomachinery impeller, as follows:(1) The cyclic symmetry structural analysis method is applied to carry out modal analysis for the tuobomachinery impeller. The effect of blade thickness mistuning on the natural frequency and mode of the tuobomachinery impeller is simulated. The evolvement of the mode with respect to frequency is analysed. The theory of vibration energy level transition is elaborated and verified.(2) Through the frequency deviation due to mistuning of blade thickness, stiffness, and circumferential uniformity, we determine the mistuning sensitivity of the frequency to these mistuning factors. The forced response of the turbomachinery impeller under wake excitation is simulated. The dynamic response of localized mode under different engine order excitation is compared.(3) The correlation of tuned free vibration characteristics with mistuning sensitivity is investigated. The frequency veering non-integer nodal diameter is obtained using cyclic symmetry structural analysis method. The correlation of tuned free vibration characteristics with mistuning sensitivity is verified though numerical simulation. A more effective method to determine the mistuning sensitivity is proposed.