Forced Response of a Mistuned Industrial Impeller With Two Different Blade Geometries, via ROM

Abstract

Numerous works have presented techniques for obtaining reduced order models (ROMs) of mistuned bladed disks. Most of these works focus in only one rotor’s stage, though some also include several stages and even the rotor shaft. However, to the authors’ knowledge, the ROM techniques available in the literature consider only one blade geometry by stage, thus making impossible their use for the case of impellers with two or more different blade geometries. This paper shows an adaptation of a previously published reduced order modeling technique in order to allow its application to the case of industrial compressor impellers incorporating two or more different blade geometries (main and splitter blades). The technique is based on Craig and Bampton’s component mode synthesis and it permits to introduce different mistuning patterns for each blade geometry while the disk is considered as a cyclic symmetric structure. The proposed technique is applied to an industrial compressor impeller in order to assess its precision and validity. Generation of finite element parent model for the real compressor via laser scanning is presented and discussed as well as simplifications used in order to generate the impeller’s ROM. Validation is carried out by comparison of predictions for the forced response of the tuned and mistuned impeller, obtained by means of the ROM and the finite element parent model. Results show that the ROM properly represents the dynamic features of the parent model in the frequency range of interest, with minimal computational cost. Furthermore, the ROM properly captures the localization phenomenon when it occurs.