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Study of Flow Characteristics behind a Sunroof Wind Deflector for Wind Noise Reduction  

Lee, Dug-Young (School of Automotive, Industrial and Mechanical Engineering, Daegu University)
Yoon, Jong-Hwan (School of Automotive, Industrial and Mechanical Engineering, Daegu University)
Shin, Jae-Hyuk (Department of Mechanical Engineering, Graduate School, Daegu University)
Kim, Sang-Kon (R&D Center, Webasto DongHee Co., Ltd.)
Publication Information
Transactions of the Korean Society of Automotive Engineers / v.17, no.1, 2009 , pp. 182-189 More about this Journal
Abstract
The noise from the sunroof can be divided into the low frequency buffeting noise and the high frequency turbulence noise generated when a car runs at the high driving speed. The wind deflector suppresses the buffeting noise generation by accelerating the vortex shedding from the front edge of sunroof opening, and guides the flow direction so that air can pass smoothly over the sunroof opening. To reduce the buffeting noise and the high frequency noise, it is very important to locate a deflector in a proper position depending on the driving speed and the sunroof opening width. The deflector's sectional shape also plays an important role in efficiently reducing the buffeting and high frequency noise. In this paper, we determined the optimum deflector's sectional shape and examined the flow characteristics behind a sunroof deflector through CFD analysis with changing the deflector height, the driving speed and the sunroof opening width. It is found that the deflector needs to be located in the higher location to control the buffeting noise by shedding the higher frequency vortices to accelerating vortices from the sunroof front edge. The deflector may act as a new noise source at the high driving speed, then it is desirable to put the deflector at the proper height to reduce the flow fluctuations and the noise generation. We also made a road test to verify CFD analysis results in this study.
Keywords
Sunroof; Deflector; Buffeting noise; Wind noise;
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  • Reference
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