Numerical investigation and experimental test on aerodynamic noises of the bionic rear view mirror in vehicles

Abstract

At present, there are some researches focusing on optimization of aerodynamic noises on rear view mirrors, but researches on bionic noise reduction of rear view mirrors are rarely reported. Therefore, with an original rear view mirror as the basic model, the paper applied a head convex hull of a dung beetle to the original rear view mirror cover to obtain a bionic rear view mirror, then conducted numerical computation for aerodynamic noises of the bionic rear view mirror and compared the computational results with the original model. Finally, in order to verify correctness of computational results of aerodynamic noises of the rear view mirror, wind tunnel test was conducted on the rear view mirror. Experimental and numerical simulation results were highly consistent in the whole frequency band, so the wind tunnel test could be replaced by numerical simulation. Only one obvious vortex was behind the bionic rear view mirror, but two obvious vortexes with the opposite rotation directions were behind the original rear view mirror. The bionic rear view mirror did not present vortexes near the lateral window, so impacts of vortexes on noises in the vehicle could be eliminated effectively. Pressure difference in front of and behind the bionic view mirror was smaller than the pressure difference in front of and behind the original rear view mirror. Pressure resistance caused by the convex structure outside the rear view mirror was reduced, so noise reduction could be promoted. The convex structure mainly affected the aerodynamic noise in mid-high frequency regions. Compared with the original rear view mirror, noise reduction effects of the bionic rear view mirror were obvious, where the noise reduction amplitude reached 10dB. Noise source size and intensity of the bionic rear view mirror were reduced obviously.

A Review of Methods Based on Nanofluids and Biomimetic Structures for the Optimization of Heat Transfer in Electronic Devices

“…Based on these drag-reduction theories, many researchers investigated non-smooth groove surfaces. Table 4 presents the current status of domestic and overseas research into trench drag-reduction [103,[110][111][112][113][114][115][116][117][118][119][120][121][122]. V-shaped groove shows the best drag reduction effect.…”

“…Deduces the geometry of the vortex street traveling wave. [121] Lateral groove Simulation Different groove size. When the height and width are the same, it shows the best drag reduction effect.…”

Experimental Study on a Generic Side-View Mirror with Slotted Cylindrical Foot

“…The result showed that inappropriate geometrical design features of sideview mirrors could significantly exacerbate the flow-induced vibration levels of the mirror assembly. Wan and Ma (2017) applied the convex body structure of the dung beetle head to the original side-view mirror cover to reduce aerodynamic noise. The study showed that the improved side-view mirror could achieve a maximum noise reduction of 10 dB in the midhigh frequency region.…”

“…Although the side mirrors are small, it still has a drag coefficient when driving at high speeds. The drag caused by the side-view mirrors generally accounts for 2-5% of the overall drag of the vehicle (Wan and Ma 2017). To reduce this drag force, the airflow over the side-view mirror needs to be low turbulence.…”

Sound Pressure Level Spectra of Automotive Side-View Mirror Models Deduced From Time-Resolved Three-Dimensional Particle Tracking Velocimetry Data With Artificial Intelligence Based Data Assimilation Method

“…To measure noise sources, wind tunnel testing is still a common method in the automotive industry [1][2][3][4][5][6][7][8].…”