Experimental Contribution Analysis of External Aeroacoustic Noise Components to Interior Noise of Simplified, Scaled Automobile Model in Wind Tunnel

The contribution analysis of various noise sources to interior noise is important, enabling to design an automobile with a low interior noise level. Here, using the Cholesky Decomposition (CD), it is proposed to decompose overall interior noise spectrum into multiple spectra, each represents the contribution of a specific noise source to the interior noise. In order to validate this method, an experiment was conducted with two speakers driven by two independent white noise sources, showing that the measured noise spectrum can successfully be decomposed into two contributions, each associated with noise radiated from one of the two speakers. Then, a simplified, scaled automobile model with one side mirror, one front and two side windows, and flat top, back, and bottom panels was tested in a wind tunnel at the airflow speed of 24 m/s. In this experiment, 14 external and 1 interior microphones were used to measure the external aeroacoustic source signals and the interior noise signal, respectively. The contribution analysis results obtained by processing the measured microphone signals show the contributions of the aeroacoustic sources of the side mirror, the front window, the vortices at the back, and the wind tunnel fan to the interior noise.