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This paper provides a method that corrects errors induced by the empty-tunnel pressure distribution in the aerodynamic forces and moments measured on an automobile in a wind tunnel. The errors are a result of wake distortion caused by the gradient in pressure over the wake. The method is applicable to open-jet and closed-wall wind tunnels. However, the primary focus is on the open tunnel because its short test-section length commonly results in this wake interference. The work is a continuation of a previous paper [4] that treated drag only at zero yaw angle. The current paper extends the correction to the remaining forces, moments and model surface pressures at all yaw angles. It is shown that the use of a second measurement in the wind tunnel, made with a perturbed pressure distribution, provides sufficient information for an accurate correction. The perturbation in pressure distribution can be achieved by extending flaps into the collector flow.

This paper presents applications of the Two-Variable method for the correction of solid-wall boundary interference of both wind tunnel and CFD data for a simplified automobile model at zero yaw angle and to a flat-plate wing over a 90° angle range. The latter model has flowfields that vary from those of a streamlined body at 0° yaw to those of a bluff body at 90° yaw. The Two-Variable method utilizes measurements on the wind tunnel walls to estimate the interference velocity components induced by the solid boundaries. The correction of the forces and moments from these interference velocities are obtained by Hackett's force model. The paper compares this method to a simpler analytical method that is more practical to apply in closed-wall wind tunnels. It is shown that the effect of the wind tunnel walls or CFD domain boundaries can accurately removed by these techniques for model/domain area ratios of up to 0.15.