Sunroof Buffeting Suppression Using a Dividing Bar 2007-01-1552

This paper presents the results of CFD study on sunroof buffeting suppression using a dividing bar. The role of a dividing bar in side window buffeting case was illustrated in a previous study [8]. For the baseline model of the selected vehicle in this study, a very high level of sunroof buffeting, 133dB, has been found. The CFD simulation shows that the buffeting noise can be significantly reduced if a dividing bar is installed at the sunroof. A further optimization study on the dividing bar demonstrates that the peak buffeting level can be reduced to 123dB for the selected vehicle if the dividing bar is installed at its optimal location, 65% of the total length from the front edge of the sunroof. The peak buffeting level can be further reduced to 100dB if the dividing bar takes its optimal width 80mm, 15% of the total length of the sunroof for this vehicle, while staying at its optimal location. The buffeting noise can be completely suppressed and the peak buffeting level can be reduced to 85dB if the dividing bar further takes its optimal thickness 45mm, 8% of the total length of the sunroof for this vehicle, while keeping its optimal width and location. For other vehicles, the optimization procedure would be the same, but the optimal parameters should be re-calculated in general. On the other hand, this study is only based on the fluid dynamic principles without considering manufacturability, styling, cost, etc. Further work is needed to utilize these results in the production environment.