Characterization of the Wind Noise Loading of Production Automobile Greenhouse Surfaces

Abstract

Flow noise reaches the automobile interior through a variety of mechanisms including the aerodynamic excitation of vibration and its reradiation from greenhouse surfaces (the roof and glass panels). This paper describes an experimental characterization of this wind noise loading and an approximate procedure for its prediction. Experimental procedures and unique instrumentation to measure parameters characterizing wavenumber-frequency spectra of the wind noise loading, i.e. wall pressure fluctuations, during wind tunnel tests of unmodified production automobiles are described. Results in the form of localized Corcos model parameters are presented. The present modeling approach is semi-empirical, utilizing normalized wall pressure spectra. Steady flow data are used to scale the normalized spectra and to identify regions of differing flow structure which have each been assigned characteristic spectra. Spatial variation in predicted pseudo-noise is compared with measured values for several test configurations.