Noise emitted from a generic side-view mirror with different aspect ratios and inclinations

Abstract

Noise radiated from flow past different configurations of the half-round mirror (HRM) mounted on a plate has been investigated using computational aeroacoustics (CAA). The stress-blended eddy simulation (SBES), together with the Ffowcs Williams–Hawkings (FW–H) acoustic analogy, was employed to predict near-field flow and far-field noise, respectively. The numerical methodology was verified and validated for the standard HRM case against several previously published numerical and experimental data sets, which provides good agreement. Further, (i) the choice of different type of grids for CAA and (ii) the applicability of methods such as the Kirchhoff integral and the FW–H using near field inputs computed from the SBES were assessed. As a next step, the effect of induced noise from the HRM for different (a) aspect ratios (AR) ranging from 1 to 2.5 and (b) inclination of the mirror toward the plate (θ) ranging from 0° to 32° was investigated. For all the investigated cases, the distribution of the radiated noise exhibits a dipole-like structure closer to the plate and a monopole-like structure away from the plate. By inclining the mirror closer to the mounting plate, the emitted noise is reduced both in the vertical and lateral directions of the wake, whereas an increase in the AR of the mirror increases the induced noise considerably. The findings from the current study can provide a deeper understanding for effectively mitigating the induced aerodynamic noise from side-view mirrors.