Analysis of Constraint State and Frequency of an Axial-Flow Compressor Blade

Abstract

The constrain condition and frequency characteristic of the blade of an axial-flow compressor are researched. Firstly, the effect of spin softening and stress stiffening on dynamic frequency is analyzed from the theoretical. Under considering the effect of spin softening and stress stiffening, the dynamic eigen-frequency of the blade are calculated, and the results show that the stress stiffening effect have significant impact on all order natural frequency, but low natural frequencies are mainly influenced by the spin softening effect. The constraints of circumferential direction and tooth surface are analyzed, according to the structure and installations of the blade. Clamping force in circumferential direction are simulated using spring element and different stiffness. The influence of different bracing rigidity on the natural frequency are analyzed, the results show that different bracing rigidity have significant impact on the natural frequency of blade, especially to the high frequencies. The size of the clamping force should be strictly controlled during the blade installation.