Effect of the Model-Sidewall Connection for a Static Airfoil Experiment

Abstract

It has been shown that the gap between an airfoil and the windtunnel wall can have a significant effect on the three-dimensional near-wall flow topology for a static angle of attack, without being detectable at the midline of an airfoil model. Understanding the interaction between model and sidewall is necessary to improve the accuracy of wind-tunnel airfoil testing and reduce the sidewall interference. The measurements in this technical note show that care must be exercised, when comparing full three-dimensional modeling of the wind tunnel and model with experiments, not to draw the wrong conclusion from a good fit between computation and experiment. In this case, a good agreement can be gained by CFD modeling that produces the wrong flow topology, but the agreement will not necessarily remain good if the test conditions change.