Calculation of the parameters of the size spread of blades in packs optimal with respect to vibration stresses

Abstract

Procedures are developed for calculating the size spread of turbomachine impellers which are most hazardous or most favorable from the viewpoint of the level of vibration stresses. The procedures are based on the proposed method of calculating forced vibrations of the blade rims with arbitrary spreads and with any packing schemes as well as on optimization methods. The initial-parameter and finite-element methods and superelement approach are used for calculating forced vibrations. The effect of blade-size spreads on vibration stresses was investigated in a wide range of exciting frequencies. Optimal sets of spread parameters were obtained for a number of types of excitation and designs of blade rims.