Aeroacoustic Vehicle Development Method Considering Realistic Wind Conditions 2023-01-1123

The aeroacoustic development of vehicles is still mainly carried out in wind tunnels under steady flow conditions, although the real situation is different. On road a vehicle experiences unsteady, turbulent flow which results for example from natural wind, wakes of other vehicles, or obstacles at the roadside in combination with side wind. These unsteady flow conditions lead to temporal variations of the wind noise inside the cabin, affecting the passengers’ comfort and thereby safety. To be able to consider also the unsteady aeroacoustics in the vehicle development process, a new method has been developed. The on-road situation is simulated in a realistic and reproducible manner in the full-scale wind tunnel of the University of Stuttgart by means of the active turbulence generator FKFS swing. The turbulence generator allows to dynamically vary the flow angle with frequency components of up to 10 Hz. By comparing the unsteady wind noise for different flow situations and different vehicles, a flow scenario has been derived which leads to representative and meaningful aeroacoustic results. The measured temporal wind noise variations are investigated using modulation analyses which have been adapted to show only relevant information in a comprehensible way. Finally, a psychoacoustic metric for rating the annoyance of unsteady as well as steady wind noise has been developed based on listening studies. The metric describes the subjective perception very well and allows to evaluate and optimize the aeroacoustics specifically regarding the passengers’ comfort. With this new method all wind noise aspects, steady and unsteady, can be determined and taken into account for the vehicle development. The evaluation and comparison of vehicles and variants is comprehensive and is focused on the passengers’ comfort.