Aeroacoustic Feedback Phenomena in Side-Branch Helmholtz Resonators: a Numerical and Experimental Analysis

The research project focuses on the investigation of aeroacoustic feedback phenomena in a flow duct component and their influence on far-field noise radiation by means of numerical and experimental analysis. Constructive feedback interactions between the aerodynamic and acoustic fields cause aeroacoustic instabilities resulting in self-sustained pressure oscillations of high amplitude that can cause severe noise emissions (i.e., whistling). A side-branch Helmholtz resonator subjected to a subsonic grazing flow is investigated as a representative benchmark of various technical applications ranging from automotive to aerospace susceptible to aeroacoustic feedback phenomena (i.e., ventilation systems, pipelines, aircraft airframes, acoustic liners). This research aims to provide additional insights into the physical mechanisms leading to the onset of aeroacoustic feedback phenomena in rigid duct components. Moreover, it aims to develop efficient methodologies to predict the aeroacoustic instability onset and accurately describe the acoustic behavior of components and systems where such feedback phenomena occur. The research approach comprises experimental aerodynamic and acoustic measurements and numerical simulations with efficient high-order solvers based on the resolution of the non-linear or linearized Navier-Stokes equations.