Advanced Simulation Method for Wind Noise Vehicle Design

Abstract

<div class="section abstract"><div class="htmlview paragraph">Summary: With the electrification of powertrains, noise inside vehicles has reached very satisfactory levels of silence. Powertrain noise, which used to dominate on combustion-powered vehicles, is now giving way to other sources of noise: rolling noise and wind noise. These noises are encountered when driving on roads and freeways and generate considerable fatigue on long journeys.</div><div class="htmlview paragraph">Wind noise is the result of turbulent and acoustic pressure fluctuations created within the flow. They are transmitted to the passenger compartment via the vibro-acoustic excitation of vehicle surfaces such as windows, floorboards, and headlining.</div><div class="htmlview paragraph">Because of their mechanical properties, windows are the surfaces that transmit the most noise into the passenger compartment. Even though acoustic pressure is much weaker in amplitude than turbulent pressure fluctuations, it still accounts for most of the noise perceived by occupants. This is because its wavelength is closer to the characteristic wavelengths of glass vibration, making it more efficient at propagating through cabin glazing.</div><div class="htmlview paragraph">Accurate modeling of these phenomena requires the coupling of CFD (Computational Fluid Dynamics) and high-frequency vibro-acoustic simulations. Among other things, CFD simulations must reproduce the creation and propagation of acoustic waves in the airflow around the vehicle; the Lattice-Boltzmann method is used for this purpose. The vibro-acoustic simulations must enable the coupling between the external aero-acoustic loading on the glazing and the propagation of noise in the passenger compartment to the occupants’ ears.</div></div>