New FKFS Technology at the Full-Scale Aeroacoustic Wind Tunnel of University of Stuttgart 2015-01-1557

For many years FKFS has operated the full-scale aeroacoustic wind tunnel of University of Stuttgart. To keep this wind tunnel as one of the most modern ones of its kind, it has again been upgraded significantly. The upgrade improved the aerodynamic as well as the aeroacoustic performance and accelerated the operational processes. Additionally, new innovative features have significantly enlarged the test capabilities. A new patented, modular belt system (FKFS first^®) allows high performance measurements for race cars in a 3-belt mode as well as efficient measurements for production vehicle development in a 5-belt mode. The belt system is accompanied by a new, larger turntable and a new under-floor balance which enables high-accuracy measurements of forces and moments also for a high resolution in time. For the elimination of parasitic forces generated at the wheel drive units, a specific correction procedure has been implemented, which is patented, too (FKFS pace^®). A new type of boundary layer conditioning system rounds up the enhanced road simulation. Unsteady aerodynamics can be investigated by means of a unique, active side wind generator (FKFS swing^®). It consists of 8 wing-like profiles with independent drives which can deflect the whole airflow around the car in the test section with a frequency of up to 10 Hz. This system can also be used for unsteady aeroacoustics. The acoustic performance of the wind tunnel has been improved mainly by acoustic linings in the first diffuser. Special patented profiles in the nozzle (FKFS besst^®) and a Helmholtz resonator suppress low frequency pulsations of the open jet very efficiently. The profiles also reduce the high-frequency broad-band noise of the wind tunnel.