There are many applications in which exterior flow over a structure is an important source for interior noise. In order to predict interior "wind noise" it is necessary to model both: (i) the spatial and spectral statistics of the exterior fluctuating surface pressures (across a broad frequency range) and (ii) the way in which these fluctuating surface pressures are transmitted through a structure and radiated as interior noise (across a broad frequency range). One approach to the former is to use an unsteady CFD model. The use of compressible CFD to characterize exterior fluctuating surface pressures for broadband interior noise problems is relatively new; the accurate prediction of both the convective and acoustic wavenumber content of the flow can therefore present some challenges. This paper has provided a numerical investigation of the spatial and spectral statistics of the fluctuating wall pressures downstream of a simplified side-mirror. The importance of spatial correlation when characterizing fluctuating surface pressures was emphasized using a simple example. The transmission of sound through a glass panel was compared when excited by a turbulent boundary layer and a diffuse acoustic field. For the same exterior pressure level, the turbulent boundary layer resulted in interior sound pressure levels that were 30 dB less than for the diffuse acoustic field. The fluctuating pressure levels downstream of a simplified side-mirror were then investigated. By performing a number of signal processing operations it was possible to plot the wavenumber content of the spatial correlation (averaged across a region of interest). Clear concentrations of energy were seen at the convective and acoustic wavenumbers. Wavenumber filtering was used to fit analytical turbulent boundary layer and diffuse acoustic field loads to the CFD data. These loads were then applied to an SEA model to analyze the different transmission paths through the panel. For the particular panel and flow conditions examined in this paper, the radiated acoustic power is dominated by non-resonant transmission acoustic transmission from 600 Hz to the coincidence frequency of the panel.


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    Title :

    Modeling interior noise due to fluctuating surface pressures from exterior flows


    Contributors:
    Cotoni, V. (author) / Blanchet, D. (author) / Shorter, P.J. (author)


    Publication date :

    2012


    Size :

    8 Seiten, 7 Bilder, 9 Quellen



    Type of media :

    Conference paper


    Type of material :

    Print


    Language :

    English




    Modeling Interior Noise due to Fluctuating Surface Pressures from Exterior flows

    Blanchet, Denis / Shorter, Phil / Cotoni, Vincent | SAE Technical Papers | 2012





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