Wind tunnel experimental study on aerodynamics and noise based on the influence of automobile rearview mirror shapes

To reduce the aerodynamic noise caused by automobile rearview mirrors, a simplified rearview mirror model was taken as the research object, and three different modeling improvement schemes were proposed: model A tilts the mirror body at 15°; model B tilts the mirror body at 30°; model C changes the cylindrical base to an elliptical base. Wind tunnel experiments were carried out on the models to analyze the variation rules of the flow field, drag, and wall pressure fluctuation with the change of the model. The particle image velocimetry (PIV) and six-component balance were used to measure the aerodynamic characteristics including the flow field and drag, and the wall microphone was applied to measure the acoustic characteristics. The results show that all three schemes can improve the flow quality in the wake area of the rearview mirror, effectively reducing the drag and the generation of aerodynamic noise. Compared to the base model, the drag coefficient and the overall sound pressure level of the wall pressure fluctuation of model B can be reduced by 18.4% and 4.6 dB in the low-mid frequency range. For model C, the corresponding results are 7.5% and 4.3 dB, respectively. The research results are beneficial for engineers in the aerodynamic and acoustic design of automobile rearview mirrors.