<p>Due to the high requirement of aerodynamic efficiencies of modern aeroengines, the tip clearances between blades and casings are becoming smaller. As a result, the possibilities of rubbings between rotating blisks and their surrounding casings are increased. Meanwhile, rotational effects exhibit more significance in the latest fan generation which have longer blade and longer cantilevered shaft. However, previous studies considering rotordynamics during the rub impact mainly focus on simplified models. It is necessary to take both realistic blades and Coriolis effect into account. Based on an academic bladed-disk model, the impact of Coriolis effect on rub-induced responses is investigated. The Craig-Bampton method using cyclic symmetry is adopted to obtain the reduced-order model. Both centrifugal and gyroscopic effects are involved in the numerical model. Real modal analysis is sufficient for Rayleigh damping, while when the gyroscopic matrix is included in the damping term, mode shapes are no longer totally in-phase or out-of-phase. Thus, a complex modal analysis has to be utilized to solve the quadratic eigenvalue problem. The responses of the flexible bladed disk are investigated under unilateral contact. Coriolis-induced frequency splits could be found in the dynamic responses, which indicates the significance of Coriolis effect on the rub-induced responses. The complex modal reduction has been successfully applied to the rub-impact problem of cyclic symmetric blisks, laying a solid foundation for the further rubbing research in which coupling effects caused by shaft bending would be considered.</p>

Balded-Disk Rubbing Interactions Considering Coriolis Effect: A Reduced Model Based on Complex Modal Analysis

Paper Proceedings: https://asmedigitalcollection.asme.org/GT/GT2021/volume/84898

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