A Method for Forced Response Analysis of Mistuned Bladed Discs With Aerodynamic Effects Included

Abstract

A method has been developed for high-accuracy analysis of forced response levels for mistuned bladed discs vibrating in gas flow. Aerodynamic damping, the interaction of vibrating blades through gas flow and the effects of structural and aerodynamic mistuning are included in the bladed disc model. The method is applicable to cases of high mechanical coupling of blade vibration through a flexible disc and, possibly shrouds, and to cases with stiff discs and low mechanical coupling. The interaction of different families of bladed disc modes is included in the analysis providing the capability of analysing bladed discs with pronounced frequency veering effects. The method allows the use of industrial-size sector models of bladed discs for analysis of forced response of a mistuned structure. The frequency response function matrix of a structurally mistuned bladed disc is derived with aerodynamic forces included. A new phenomenon of reducing bladed disc forced response by mistuning to levels that are several times lower than those of their tuned counterparts is revealed and explained.