On the Effect of Flexibility for In-Duct Plates with Focus on Aeroacoustics

Abstract

The flow of air around an angled steel plate in a duct generates noise. Previous experimental studies show that the noise is reduced if the plate is allowed to be flexible, however the underlying mechanisms are not fully understood. Therefore it is desirable to find an accurate and affordable numerical solution to the problem. In this thesis, the stiff and the flexible plate are simulated using the commercial CFD software Star CCM+. Sound generation is then estimated by applying a dipole approximation of Curle’s acoustic analogy. The results show that the velocity field and sound generation can be accurately predicted for the stiff plate and that the Star CCM+ FSI solver accurately predicts the plate motion. However, the sound reduction for the flexible plate is not captured. The reason for the discrepancies between simulation and experiments in terms of sound generation are unclear, however the motion of the plate is believed to make the dipole sound approximation an unsuitable approach.