A computational fluid dynamics simulation method based on large eddy simulation is presented and applied to compute the sunroof buffeting of a sport utility vehicle. The simulation result, i.e. the buffeting level curve, coincides well with the road test. The simulation method is then employed to investigate the sunroof buffeting of a vehicle during the development process in the range of 30 km/h–90 km/h. The results show that the most severe sunroof buffeting occurs at 70 km/h, which corresponds to the resonant frequency of the cabin. Flow field visualizations reveal that strong pressure fluctuations are generated inside the cabin due to vortex shedding from the leading edge and impinging onto the trailing edge of the sunroof opening, which explains the mechanism of sunroof buffeting. A new deflector with a gap and a notched upper edge is designed to replace the original castle type deflector. The simulation results show that the newly designed deflector can reduce the buffeting level to 97.9 dB; that is, the sunroof buffeting is completely eliminated. Moreover, the phenomenon of sunroof buffeting reduction is explained by comparing and analyzing the flow field between the newly designed deflector and the original deflector.

中文翻译：

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汽车天窗抖振的计算研究与被动控制

提出了一种基于大涡模拟的计算流体动力学模拟方法，并将其应用于计算越野车的天窗抖抖。仿真结果，即抖振水平曲线，与路测非常吻合。然后，采用模拟方法研究在开发过程中车辆在30 km / h–90 km / h范围内的天窗抖抖现象。结果表明，最严重的天窗抖振发生在70 km / h时，这对应于机舱的共振频率。流场可视化显示，由于旋涡从前缘脱落并撞击到天窗开口的后缘，导致机舱内部产生强烈的压力波动，这说明了天窗抖振的机理。带有间隙和带缺口的上边缘的新导流板旨在替代原始的城堡式导流板。仿真结果表明，新设计的导流板可以将抖振水平降低到97.9 dB。即，完全消除了天窗抖振。此外，通过比较和分析新设计的导流板与原始导流板之间的流场，来解释天窗抖抖现象。