Computational study on the passive control of sunroof buffeting using a sub-cavity

Abstract

A feasible simulation method based on large eddy simulation (LES) was presented and employed to investigate the sunroof buffeting characteristics of a vehicle with a castellated deflector at 30–90 kph. The simulation results reveals that the sunroof buffeting reached its maximum, 135.9 dB, at 70 kph (the baseline). To suppress the sunroof buffeting SPL, it has been proposed to construct a sub-cavity by attaching an inclined baffle near the leading edge of the sunroof. Its sunroof buffeting was computed at 70 kph (the case 0). As a result, the sunroof buffeting SPL was reduced by 27.8 dB in comparison with the baseline, which proves the positive effects of the sub-cavity on sunroof buffeting reduction. Then, the flow fields were visualized to explain the phenomenon of sunroof buffeting reduction after replacing the castellated deflector with the sub-cavity. Furthermore, the size variable A, L of the sub-cavity were optimized to search the minimum response SPL. The final optimal design was obtained with the size variable A = 63°, L = 56 mm and the response SPL = 102.8 dB. The reduction of sunroof buffeting reached 33.6 dB and 5.8 dB, respectively, compared with the baseline and the case 0. Therefore, the optimal sub-cavity can suppress the sunroof buffeting effectively.