Identification of acoustic wavenumber component of fluctuating surface pressure for flow noise analysis

The importance of flow noise is increasing with the increasing popularity of quiet electric vehicles. In general, flow noise covers a wide frequency range and usually the high frequency flow noise is important for the vehicle quality because of the increased sensitivity of human perception to high frequency noise. For predicting high frequency noise, statistical energy analysis (SEA) is often used in the prediction of acoustic insulation and absorption. Some of SEA modeling for flow noise transmission has been reported in the literature. However, most of the SEA modeling needs CFD results which require huge computation time. In vehicle design, sometimes the time required for improvements does not permit time for development of CFD models. In such situations, easy and fast diagnostic method like energy transmission contribution analysis is required. In this paper, the mechanism of the flow noise transmission is reviewed especially in the case of low speed flow of around 80 km/h. The acoustic wavenumber component of fluctuating surface pressure is dominant source of flow noise transmission for low speed flow. Therefore, the acoustic wavenumber component identification using conventional acoustic SEA model and the wind tunnel test results is presented. The identified acoustic wavenumber component is validated by comparing with the acoustic wavenumber component identified from the wavenumber-frequency spectrum to that computed using a CFD model.