Determination of the Acoustic and Hydrodynamic Contributions to the Vibrational Response of an Air-Conveying Rectangular Duct

This paper focuses on the vibratory response of a rectangular duct of finite length excited by an internal turbulent flow. The wall pressure distribution is decomposed into a hydrodynamic and acoustic contribution. Two configurations are investigated: (i) a straight duct with no singularity, in which duct acoustic modes are excited by the TBL and (ii) a straight duct with a diaphragm inserted upstream generating a localized acoustic source. The acoustic contribution is either measured via cross-spectra-based methods or calculated using Computational Fluid Dynamics and aeroacoustic analogies. Semi-analytical predictions are compared with experimental results. It is concluded that in both scenarios, the acoustic contribution is largely dominant.