Time-variable normal contact force influence on dry-friction damping of self-excited vibration of bladed turbine wheel

0549725 - ÚT 2022 RIV PL eng A - Abstrakt
Šnábl, Pavel - Pešek, Luděk - Prasad, Chandra Shekhar
Time-variable normal contact force influence on dry-friction damping of self-excited vibration of bladed turbine wheel.
16th Dynamical systems theory and applications. Lodz: Lodz University of Technology, 2021 - (Awrejcewicz, J.; Kazmierczak, M.; Mrozowski, J.; Olejnik, P.). s. 708-708. ISBN 978-83-66741-20-1.
[Dynamical systems - Theory and Applications /16./. 06.12.2021-09.12.2021, on-line]
Grant CEP: GA ČR(CZ) GA20-26779S
Institucionální podpora: RVO:61388998
Klíčová slova: turbine blades * dry-friction contact * flutter * travelling wave * Van der Pol model
Obor OECD: Applied mechanics
http://repozytorium.p.lodz.pl/handle/11652/4116

Recently [1-2], the new calculation approach based on modal synthesis method is proposed for evaluation of structural and dry-friction damping effect on self-excited vibrations due to aeroelastic
instability in the bladed turbine wheels. Due to the modal reduction, the calculations are made computationally very efficient. The method will be herein used to study a dry-friction damping of
self-excited vibration of an industrial turbine wheel with 66 blades. The aerodynamic excitation arises from the spatially periodical flow of steam through the stator blade cascade. The self-excited aeroelastic forces of blades are described by Van der Pol model [3]. For evaluation of damping effect, the blade tie-boss couplings are applied on this particular turbine wheel. Therefore, neighboring blades are interconnected by rigid arms that are on one side fixed to one blade and are in friction contact ontheir free side with the other blade. The contact point pairs of two neighboring blades overlap in undeformed state of the cascade and static normal contact forces are prescribed. The relative contactdisplacements due to blade cascade deformation are calculated from kinematics of relative blade motions. Due to relative normal motions in contacts, the prescribed contact forces will vary in timeduring vibration. In the contribution, the effect of variable magnitude of normal contact forces with respect to the angle of contact surfaces on the wheel dynamics and on level of friction damping will be analyzed. Friction forces in contacts are driven by the modified Coulomb friction law. The analysis will be oriented on the narrow frequency range and on the case when a slip motion is prevailing in the contacts.
Trvalý link: http://hdl.handle.net/11104/0327437