This article has discussed the problem of aerodynamic noise passing through the vibration of a structure. Several phenomena have been revealed through the vision of the wall pressure field in the wavenumber domain that enables the separation of the aerodynamic and the acoustic components. From a computational point of view, two large families stand today. There are approaches of fluid mechanics which seek to simulate the flow and to extract the wall pressure excitation. The difficulties are based on computational means that are needed. The latest developments concern the consideration of a compressible fluid which takes into account the acoustic component intrinsically and the vibration effect that can change the wall pressure. The other family is more widely used in vibroacoustic where empirical models based on auto-power and crosspower spectra are used. Most of these models do not take into account the acoustic component, whereas it can have a very important role in the noise radiated by the structure. On the experimental point of view, extracting the acoustic component is possible through the 2D Fourier transform of parietal pressure field measured with a high spatial resolution. This technique requires a special device replacing the vibrating structure and assumes a weak coupling. The idea of using the structure as a sensor was also investigated. This is an inverse problem of vibrations. The experimental results suggest that this method can extract the acoustic component, because the inverse problem and the structure constitute low-pass wavenumber filters. This inverse approach seems particularly interesting and original future developments can be envisaged. For example, the coupling with the real-time acoustic holography technique could achieve identification from the internal acoustic fields. One can also think to optical holography techniques that can give high resolutions in time and space with use of a high-speed camera.
Prospects for vibroacoustic methods in automotive industry: Analysis of aeroacoustic excitations
2010
10 Seiten, 21 Bilder, 34 Quellen
Conference paper
Storage medium
English
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