Prediction of Mirror Induced Wind Noise Using CFD-FEM Approach

Wind noise is becoming important for automotive development due to significant reductions in road and engine noise. This aerodynamic noise is dominant at highway speeds and contributes towards higher frequency noise (>250Hz). In automotive industry accurate prediction and control of noise sources results in improved customer satisfaction. The aerodynamic noise prediction and vehicle component design optimization is generally executed through very expensive wind tunnel testing. Even with the recent advances in the computational power, predicting the flow induced noise sources is still a challenging and computationally expensive problem. A typical case of fluid-solid interaction at higher speeds results into broadband noise and it is inherently an unsteady phenomenon. To capture such a broad range of frequency, Detached Eddy Simulation (DES) has been proven to be the most practical and fairly accurate technique as sighted in literature. Present work talks about the application of Detached Eddy Simulation (DES), as a computationally faster and cheaper method for predicting the flow and sound generation. In the present case a mirror mounted on SUV has been investigated numerically using Finite Volume Code, FLUENT in flow domain and FEM methodology with appropriate aero acoustic analogies in structural domain. In this study, the effect of mirror configuration on the vehicle interior noise has been presented. The analysis has been carried out on baseline mirror, new mirror (door mounted) and no mirror cases. The average sound pressure level inside the vehicle observed to be reduced by 17% with door mounted mirror compared to baseline mirror case.