At high cruising speed, the car A-pillars generate turbulent air flow around the vehicle. The resulting aerodynamic pressure applied on the windows significantly contributes to the total cabin noise. In order to predict this particular noise contribution, the physic of both the flow and the cabin needs to be accurately modeled.
This paper presents an efficient methodology to predict the turbulent noise transmission through the car windows. The method relies on a two-step approach: the first step is the computation of the exterior aero-dynamic field using an unsteady CFD solver (PowerFLOW); the second step consists in the computation of the acoustic propagation inside the cabin using a finite element vibro-acoustic solver (ACTRAN).
The simplified car cabin of Hyundai Motor Company, studied in this paper, involves aluminum skin, windows, sealant, inner air cavity and acoustic treatment inside the passenger compartment (porous material, damping layer). A pure vibro-acoustic model with hammer shock excitation on a window is first built. Acoustic results inside the cabin are then correlated with measurements in order to validate the vibro-acoustic modeling of the cabin, which is deemed as invariant regarding the imposed excitation types. Finally, aerodynamic pressure results from CFD are mapped on the structure mesh of the two lateral windows and the front windshield, causing structure vibration and consequently acoustic response in the cabin. Four flow conditions are studied, involving two cruising speeds (110km/h and 130km/h) and two yaw angles (0° and 10° orientations). The total wind noise level results and the relative contributions of the different windows/windshield are presented and compared to measurements.