Abstract

There seems to be a lack of clear and systematic understanding of physical behaviour and mechanisms of mistuned bladerows, particularly in the context of the aerodynamic mistuning versus the structural (frequency) mistuning. A high-fidelity fully-coupled method is desirable to investigate the vibration characteristics of aeroelasticity problems with strong fluid-structure interaction effects, as well as blade mistuning effects. In the present work, the direct nonlinear time-domain fully-coupled method is adopted to investigate the dynamics mechanism of a mistuned oscillating cascade. The main objectives are two-folds, firstly to elucidate the basic vibration characteristics of a mistuned bladerow, and secondly to examine the aeroelastic effects of mistuning. Three conditions of interest are considered: a) the structural mistuning only, b) the aerodynamic mistuning only, and c) a combination of the two. The present results show that firstly a mistuned configuration tends to vibrate with the same frequency and a predominantly constant inter-blade phase-angle. Vibration amplitudes of the blades vary significantly with a strong mode localization effect for the structural mistuning. For the concurrent structural-aerodynamic mistuning, the localization is stronger than in the standalone structural mistuning case. Secondly, a monotonic increase of the aeroelastic stability with the structural mistuning magnitude is observed. On the other hand, the aerodynamically mistuned cascade shows a stabilizing effect with a small amount of mistuning but exhibits a destabilizing effect with a large mistuning. Furthermore... see paper for the full abstract

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