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This paper reports on an exploratory automotive test which was undertaken in the NASA Langley Research Center 14 by 22 wind tunnel in the Fall of 2003. The test was collaboration between Old Dominion University, who supplied the automotive balance, NASA, who provided wind tunnel time, and Penske Racing South, who provided an instrumented test vehicle. The test generated a rather unique data set, encompassing whole body forces, surface pressures, and floor boundary layer profiles, measured on the same test article, with both an open jet and closed jet test section, utilizing the variable configuration of the 14 by 22. The nominal test velocity was 60 m/s, the nominal blockage was 7.4%, and the yaw angle ranged from −6 to +6 degrees. Results indicate substantial interference effects, as expected, with around 19% higher drag (uncorrected) in the closed configuration, relative to open. The corresponding front and rear downforce values were 14% and 13% higher respectively.

The issue of ground simulation in wind tunnels has led to the development of Moving Ground Plane (MGP, aka rolling road) systems of various types. Motorsports aerodynamics has perhaps been the primary application to date, where the range of vehicle yaw angles tends to be quite limited. In fact, since yaw angles are typically developed as result of vehicle slip in cornering, or asymmetric set-up in the case of stock cars, they are limited to a few degrees. Further, since in both cases the vehicle centerline typically rotates with respect to the relative velocity vector (i.e. simulating vehicle slip in cornering), it seems clear that yawing the vehicle in the wind tunnel above a fixed (non-rotated) MGP is a valid simulation option. In the case of vehicles operating in strong crosswind conditions, for example commercial vehicles (heavy trucks) on interstate highways, the situation is more complex.