Abstract



The computation of the friction saturated vibratory response of an aerodynamically unstable bladeddisk in a realistic config uration is a formidable numerical task, even for the simplified case of assuming the aerodynamic forces to be linear. The non linear friction forces effectively couple different traveling waves modes and, in order to properly capture the dynamics of the sys tem, large time simulations are typically required to reach a fi nal, saturated state. Despite of all the above complications, the output of the system (in the friction microslip regime) is not that complex: it typically consists of a superposition of the aeroelas tic unstable traveling waves (TW), which oscillate at the elastic modal frequency and exhibit also a modulation in a much longer time scale. This large time modulation over the purely elastic os cillation is due to both, the small aerodynamic effects and the small nonlinear friction forces. The correct computation of these two small effects (small as compared with the elastic forces) is crucial to determine the final amplitude of the flutter vibration, which basically results from its balance. In this work we ap ply asymptotic techniques to obtain a simplified model that gives only the slow time dynamics of the amplitudes of the travel ing waves, filtering out the fast elastic oscillation. We analyze the stability of the resulting nonlinear TW solutions, and we also compare quantitatively the results of the simplified model with those from a more detailed model that is much more expensive to compute.  
International

Si 
Congress

ASME Turbo Expo 2014 

960 
Place


Reviewers

Si 
ISBN/ISSN

9780791845677 


Start Date

16/06/2014 
End Date

20/06/2014 
From page

1 
To page

11 

2014 Proceedings of the Asme Turbo Expo 2014 