The Aerodynamics Phenomena of a Particular Bass-Reflex Port

The aim of this paper is to study the aerodynamics phenomena of a particular bass-reflex port that causes unwanted noise in the audible frequency range. After discarding structural and mechanical vibration issues, the hypothesis that vortex shedding could be the source of the noise has been considered. Experimental and numerical evidences of the vortex, an analysis of its noise and the similarities between the real performance and the simulated one are presented. The simulations have been performed with axisymmetric geometries with the open source OpenFOAM toolbox. Additionally, three different experiments were carried out. First, acoustic signal experiments were done to analyze the response of the bass-reflex ports. Second, a mechanical vibration was tested in order to discard this source of noise. A good agreement has been found between numerical and experimental results, especially in the frequency band of the detected noise, around 1200 Hz. The presented CFD approach has proved a useful and cost-effective tool to face this kind of phenomena.