3D interaction in bladed rotor-to-stator contact
Résumé
Reducing the clearance between blade tips and casing is an important factor in increasing the performance of turbomachines such as turbofan engines. However, small clearances lead to more chances of rotor-stator contact, which can cause unstable vibrations. To improve the prediction of such contact-related phenomena, this paper proposes a model that includes potential contacts between the fan blade tips and their surrounding casing. This phenomenological model consists of a fully flexible bladed rotor and a flexible casing. The bladed rotor model is built according to the method developed by Lesaffre and based on the approximations used by Sinha [2]. The casing model is composed of an elastic ring with isotropic suspension. Two different contact formulations have been developed: a 3D contact detection law, which incorporates 3D model kinematics along with 3D local geometry of the contact area, is compared to a simpler formulation. For both formulations, once the clearance has been consumed, contact forces are introduced with normal contact stiffness, and friction is considered using Coulomb’s Law. In an initial step, linear harmonic results serve to compare these contact formulations in their ability to detect contact. Next, the stability of balanced static solutions is studied and transient analyses are carried out to confirm the static results. Study results highlight the influence of 3D kinematics and 3D local geometry on both contact detection and the dynamic stability of the system subjected to blade-casing contact.
Origine : Fichiers produits par l'(les) auteur(s)
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