Damping of flutter oscillations by dry friction contacts

0495845 - ÚT 2019 RIV CZ eng A - Abstract
Půst, Ladislav - Pešek, Luděk - Šnábl, Pavel
Damping of flutter oscillations by dry friction contacts.
Computational Mechanics 2018 - Book of extended abstracts. Plzeň: University of West Bohemia, Plzeň, 2018 - (Adámek, V.; Jonášová, A.). s. 85-86. ISBN 978-80-261-0819-1.
[Computational Mechanics 2018 /34./. 31.10.2018-02.11.2018, Srní]
R&D Projects: GA ČR GA16-04546S
Institutional support: RVO:61388998
Keywords : flutter oscillations of turbine blades * dry friction * damping of vibration * modes * nodal diameters
OECD category: Applied mechanics

Self-excited flutter vibrations of turbine blades are very dangerous phenomena for the service life of turbines. The various design treatments are therefore applied for suppression of blades’ flutter vibrations. The in-troduction of dry friction elements is one of the very effective methods.
The dynamic behavior of a computational model of 30-blades turbine wheel is investigated in this paper. Due to the narrow frequency range, the blades can be modelled as systems with one degree of freedom and the blades cascade has then 30 eigen-frequencies. The blades in the rotating blades cascade are excited by aerodynamic forces arising from the spatially periodical flow of steam through the stator blades cascade. This flow produces both forced vibration and self-excited vibrations of blades – flutter. The simple Van der Pol models of excitation aero-elastic forces, acting on individual blades are considered. The possibility of application of dry friction elements on reduction or even on full elimination of these dangerous vibrations will be presented on several examples. It was shown that the dry friction forces needed for suppression of dangerous flutter vibrations strongly depends on the complexity of modes and they are inversely proportional to the number of nodal diameters in modes of vibrations.

Permanent Link: http://hdl.handle.net/11104/0289918