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 presents a numerical investigation of the spatial and spectral statistics contained in the flow downstream of a simplified side-mirror. Two distinct concentrations of energy are observed in wavenumber space at the convective and acoustic wavenumbers. Using wavenumber filtering it is then possible to describe a complex windnoise source in terms of the superposition of two simple analytical sources (that can be fit to CFD data). An example is presented in which the fluctuating surface pressures are applied to a side glass and a SEA model is used to predict interior noise.
2012 – ISMA Leuven, Belgium
Vincent Cotoni (ESI Group, USA)
Denis Blanchet (ESI Group, Germany)
Phil Shorter (ESI Group, USA)