Dynamics Analysis Of Mistuned Impeller And Intentional Mistuning Optimization Based On Lumped-Parameter Model

Impeller used in aero engine is typically cyclic symmetrical,so conventionally it was regarded as a revolution part created by rotating one sector when design and analysis.However,in reality distinctions such as inhomogeneous material,machining error and wear in operation destroy the cyclic symmetry,which often is referred as mistuning.Impeller is very sensitive to mistuning.Even a little level of mistuning will cause fiercely variation of vibration,and finally cause high cycle fatigue.For this reason,research of mistuning and search for an effective method to suppress mistuning are very important to improve the lifetime of the impeller.In this paper,some basic concepts of mistuning were introduced,and related researches domestically and abroad were summarized with focus.Firstly,three models mainly used in mistuning analysis are introduced.The dynamic of the mistuned impeller is analyzed with the lumped parameter model.The result reveals that the mistuning leads to vibration localization and frequency veering.The energy of vibration cannot propagate to other sectors so that the magnitude of the vibration is amplified at the specific area because of mistuning.Secondly,the relationship between mistuning pattern and amplification factor is investigated by simulation and theoretical derivation.That the intentional mistuning does suppress the mistuned impeller with Monte Carlo Simulations is validated,and the relationship between validity and magnitude of intentional mistuning is pointed out.The sensitivity of mistuning amplification factor respect to mistuning parameter is analyzed and the mistuned impeller is optimized.Finally,the relationship between mistuning parameters and machining errors is analyzed.How the machining errors affect the mistuning pattern is explored with principal component analysis method.A method to suppress vibration is proposed from the perspective of machining.