Whirl Flutter Suppression With Passive Dynamic Vibration Absorbers

Abstract

Aeroelastic phenomena have significantly influenced the design of aircraft and engines throughout the history of aviation. A prominent example of such a challenge is whirl flutter-an aeroelastic instability that occurs due to the interaction between aerodynamic forces and gyroscopic effects in rotating parts like propellers and fans. This form of instability, rooted in the inherent dynamics of the system, can result in severe and potentially catastrophic outcomes. In recent years, whirl flutter has gained growing attention as a critical concern, particularly with the rise of advanced tiltrotor aircraft, distributed propulsion systems, and other cutting-edge rotorcraft technologies. This study aims to expand the speed range by increasing the whirl flutter speed in vertical propeller systems by adding a passive dynamic vibration absorber to the system. In the newly created dynamic system, the modal damping and frequency behavior of the system is examined by using the standard eigenvalue problem solution. In addition, a baseline system was used and parameters are created to see the passive dynamic vibration absorber effects fully. Numerical simulation results indicate that this approach can effectively enhance the aircraft's critical whirl flutter speed. The extent of this improvement is strongly influenced by key parameters, particularly the mass ratio between the dynamic vibration absorber and the propeller, as well as the frequency ratio between their respective vibration modes. Optimizing these ratios allows the dynamic vibration absorber to efficiently counteract the destabilizing aeroelastic forces, thereby raising the onset speed of whirl flutter and improving the overall stability margin of the system.