Prediction of the Interior Noise Level for Automotive Applications Based on Time-Domain Methods

The level of wind noise in the cabin of road vehicles is an important factor in passenger comfort. For current road vehicles the radiated sound produced from the flow around the side mirror is a main contributor to the interior noise level at medium to high driving speeds. In order to estimate the acoustic performance in the early stages of the design process, a computational method is required. A complete simulation chain is presented consisting of prediction methods for the exterior noise radiated from the side mirror onto the side window, its transmission through the side window, and its radiation into the vehicle cabin. The approach is based on the solution of the differential bending and acoustic wave equations in time domain, which are extended respectively by additional modelling terms and boundary conditions to ensure frequency dependent damping. The side window and the cabin are fully resolved, allowing for the determination of the noise level at the driver's ear position as a design target value, which is not usually offered by traditional SEA methods. The simulation chain is validated on a full scale generic test body and its application to real passenger vehicles through comparison with wind tunnel measurements.