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The Windshear Rolling Road Wind Tunnel in Concord, North Carolina, is a full-scale commercial wind tunnel conceived primarily as a facility to serve the various motorsports communities, although it has already expanded beyond that base into production car and truck testing. The wind tunnel is a 3/4-open-jet, closed-return design with a 16.7 m₂ nozzle, a wide-belt moving ground plane, and a top speed of 80 m/s (180 mph). This paper describes the project history and design philosophy of the wind tunnel, commissioning results, and an overview of the force measurement methods on the wide-belt rolling road. Some results of a recently completed correlation program are presented, along with performance validation results that include repeatability and reproducibility as well as an assessment of boundary corrections.

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.