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There has been significant progress in developing test facilities for automotive wind noise and automotive components since the early 1990s. The test technology is critical to the development of modern vehicles, and essentially every major automotive manufacturer owns and operates their own aeroacoustic wind tunnel, or has rental access to one and conducts a significant amount of wind noise testing. The current status for climatic wind tunnels is that many new CWTs are being defined with acoustic test requirements. These test capabilities in AAWTs and CWTs will continue to enable the development of vehicles with better wind noise attributes, fewer problems with sunroof ‘booming’, and lower noise levels for HVAC and auxiliary systems. In the future, it is expected that the test demand for AAWTs and CWTs with low acoustic background noise will continue to increase as customers expect better automotive products, especially across more of the product line.

Low frequency pressure oscillations in open jet wind tunnels are produced by vortices shed from the nozzle exit coupled with several feedback mechanisms in the circuit. These undesired pressure fluctuations can cause structural vibrations, reduction of flow quality, and delays in delivery of newly-built wind tunnels. One effective method to mitigate this problem is incorporation of Helmholtz resonators in the wind tunnel circuit. In this paper important factors in the design of Helmholtz resonators for open jet wind tunnels are described and a specific design procedure is outlined. Finally, successful design and installation of Helmholtz resonators in several modern open jet wind tunnels is reported.

The new BMW Aerodynamisches Versuchszentrum (AVZ) wind tunnel center includes a full-scale wind tunnel, "The BMW Windkanal" and an aerodynamic laboratory "The BMW AEROLAB." The AVZ facility incorporates numerous new technology features that provide design engineers with new tools for aerodynamic optimization of vehicles. The AVZ features a single-belt rolling road in the AEROLAB and a five-belt rolling road in the Windkanal for underbody aerodynamic simulation. Each of these rolling road types has distinct advantages, and BMW will leverage the advantages of each system. The AEROLAB features two overhead traverses that can be configured to study vehicle drafting, and both static and dynamic passing maneuvers. To accurately simulate "on-road" aerodynamic forces, a novel collector/flow stabilizer was developed that produces a very flat axial static pressure distribution. The flat static pressure distribution represents a significant improvement relative to other open jet wind tunnels.