3D aeroacoustic simulations of a flow-excited Helmholtz resonator

Rucz, Péter (2020) 3D aeroacoustic simulations of a flow-excited Helmholtz resonator. In: DAGA 2020 - 46. Jahrestagung für Akustik, Hannover, Germany.

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Abstract

The flow-excited Helmholtz resonator is a classical example of acoustical resonance induced by fluid flow. When the frequency of the hydrodynamic instabilities of the shear layer formed at the orifice of the cavity is close to the natural resonance frequency of the resonator, high amplitude pressure oscillations occur, and a strong acoustical feedback on the shear layer is observed. Similar phenomena of sound production are also responsible for the noise amplification in ventilation ducts with side branches and the sound generation of air reed wind instruments, for example. This paper presents three-dimensional aeroacoustic simulations of a Helmholtz resonator excited by grazing flow in different configurations. First, the oscillations of the shear layer are analyzed without acoustical feedback using incompressible simulations. Then, the acoustical impulse response of the resonator is evaluated in the absence of the flow excitation. Finally, flow induced acoustical resonance is examined at different flow speeds by means of compressible large eddy simulations. All cases are implemented using the OpenFOAM software package. The results of numerical simulations are compared with previous 2D models and experimental as well as computational data published earlier by other authors.

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