Experimental and numerical investigation into effects of weather-strip on transmission of wind noise through side-window of automobile

When the automobile runs at high speed, cabin interior noise is dominantly caused by external flow disturbance, so-called wind noise, which is transmitted through the windshield. Therefore, the interior sound of the automobile is affected by three kinds of physical mechanisms: the external flow disturbances consisting of incompressible and compressible pressure fluctuations, the vibrational characteristics of the windshield, and the acoustic properties of the inside wall of the cabin. In this study, the effects of the weather strip of side-window on the interior wind noise are investigated using numerical and experimental approaches. The primary function of the weather-strip made of a rubber material that exhibits strong nonlinear dynamic behavior is to block dust, water, and noise from outside to inside. Constraining the vibration of side-windows on its three side edges, the weather-strip indirectly affects the transmission of external wind noise through the side-window. The simplified vehicle cabin only with a real front door is manufactured to assess the interior wind noise. The front door includes the real side-window with the weather-strip. First, a modal impact hammer test on the side-window was performed to verify the numerical method for the vibration analysis. Second, the transfer path analysis was conducted to analyze the acoustic properties of the inside wall of the cabin. In this step, the reverberation time is measured to characterize the sound absorption property of the cabin. Third, the external flow disturbance is predicted by using the high-resolution LES technique. Finally, the vibro-acoustics analysis was performed by using the pressure fluctuations on the side-window obtained from the LES as the input. Two-types of weather-strips are considered. The predicted results for the interior sound due to the external flow excitations were compared with the measured ones, which shows good agreement between two results. The effects of the detailed shapes of the different weather strips on the interior sound due to external flow disturbances were analyzed. These results reveal that the current numerical methodology can be used as a design and analysis tool for the weather stip to block wind noise effectively.