Dynamic Multi-Stage Analysis of a Mistuned Aircraft Rotor with Foreign Object Ingestion

Abstract

A dynamic multi-stage analysis was carried on an aircraft engine with a foreign object in its inlet. The analysed aircraft engine rotor included seven compressor stage and one turbine stage. Finite element method is used to analyse multistage coupling caused by the low engine order simultaneous excitation of the mistuned first and second compressor bladed discs and turbine bladed disc. Low EO excitation may occur due to foreign object ingestion, e.g. a bird strike. Blade mistuning and multi-stage coupling causes individual blades and bladed discs to vibrate simultaneously in particular stages. More blade stress peaks appeared in the mistuned system than in the tuned system, which shows that mistuning causes multistage coupling. This study has shown for the first time that mistuned compressor and a turbine bladed discs on a shaft have higher individual blade stress peaks and a different blade-to-blade stress distribution than mistuned bladed discs without a shaft. This shows that multistage coupling is very important. Mistuning effects were analysed for a specific aero-engine with one specific mistuning pattern and an exact amplification. However, the described effects are valid for other mistuning patterns. If we change the mistuning pattern on one bladed disc, the multistage coupling effects will also change but the general conclusions will be the same.