Optimization of wind resistance in commercial vehicles with consideration of sunroof buffeting noise

The aim of this study was to reduce the aerodynamic resistance coefficient of heavy commercial vehicles and buffeting noise that occurs when a sunroof is opened. Computational fluid dynamics was used to establish a numerical simulation model of wind resistance and buffeting noise. Analysis shows that the main influences on aerodynamic resistance are the airflow impact on the roof dome and the wake vortex behind the cab. Sunroof buffeting noise is caused by a low-pressure turbulent vortex generated at the forehead of the cab and falls off at the sunroof. A strategy for reducing the wind resistance coefficient and sunroof buffeting noise is proposed, which involves optimizing the sun visor installation angle and roof dome shape. The optimal strategy is to increase the sun visor installation angle by 4° and use the Scheme 2 roof dome. After optimization, the aerodynamic resistance coefficient of the commercial vehicle was reduced by 2.07% and the sound pressure level of sunroof buffeting noise was reduced by 18.3 dB. Hence, the effect of optimization was obvious. This work provides guidance for reducing drag and buffeting noise in commercial vehicles.