Session: 22-01 Fan and LPT Flutter

Paper Number: 153705

A Parametric Study on the Influence of Acoustic Treatments in Fan Flutter 

The presence of acoustic liners to suppress community noise is a common situation in modern turbo engines. These devices are tuned so that they are more effective in the high frequency band. Recent investigations have drawn attention to the effect of acoustically treated walls into the range of lower frequencies where fan flutter is present. The intake of a fan can exhibit a self-feedback mechanism where the acoustic pressure waves reflected at the inlet can produce flutter when they reach back to the fan, a phenomenon that is known as flutter bite. It was shown that the presence of an acoustic liner can have a large impact to this mechanism, in some cases providing a positive effect towards the suppression flutter. Therefore, this work expands and explores this concept further by conducting a study of the impact of different parameters related to the acoustic liners. This parametric study encompass physical quantities such as the length and the depth of the liner, its position in the intake, and the value of the impedance. The effect of these parameters is assessed by computing the stability charts of representative compressor maps as a function of the axial Mach number and the elastic frequency of the fan blades. 

Presenting Author: Javier González-Monge Universidad Politécnica de Madrid

Presenting Author Biography: Javier is a final year PhD student from Universidad Politécnica de Madrid. His research focus has been the study of nonlinear friction effects in turbomachinery. Additionally, these last years he has been studying the fan flutter instability due to acoustic mechanisms in the fan intake, paying special attention to the presence of liners.

Authors:

Javier González-Monge Universidad Politécnica de Madrid
Roque Corral Universidad Politécnica de Madrid
Mehdi Vahdati Universidad Politécnica de Madrid