A Numerical Study of Trailing Edge Serrations on Sunroof Buffeting Noise Reduction 2017-01-0441

A numerical study on sunroof noise reduction is carried out. One of the strategies to suppress the noise is to break down the strong vortices impinging upon the trailing edge of the sunroof into smaller eddies. In the current study, a serrated sunroof trailing edge with sinusoidal profiles of wavelengths is investigated for the buffeting noise reduction. A number of combinations of wavelengths and amplitudes of sinusoidal profiles is employed to examine the effects of trailing edge serrations on the noise reduction. A generic vehicle model is used in the study and a straight trailing edge is considered as a baseline. The results indicate that the trailing edge serration has a significant impact on the sound pressure level (SPL) in the vehicle cabin and it can reduce the SPL by up to 10~15 dB for the buffeting frequency. In addition, the transient flow field visualization and vorticity magnitude contours substantiate that the large shedding vortices are broken down into small eddies by using the serrated trailing edges. As a result, the SPL in the cabin is reduced. Furthermore the effectiveness of the trailing edge serrations is investigated for various freestream velocities. The results demonstrate that the trailing edge serration strategy is a promising solution for reducing automobile sunroof buffeting noise.