Unsteady Loading of a Wing in Convective Streamwise Gusts*

The aerodynamic response of wings in unsteady streamwise gusts has been primarily researched in closed test section environments, which impose a spatially uniform yet time-varying change in velocity. However, these conditions do not necessarily represent free flight conditions where the gust velocity may vary spatially. In this study, the aerodynamic performance is examined for a wing in a convective gust generated in an open test section environment, which imposes both temporal and spatial velocity gradients. Unsteady surface pressure, forces, and moments were measured for a NACA 0015 wing and analyzed with respect to the spatial velocity distribution imposed by the convective gusts. The surface pressure scales with the local velocity, thereby altering the unsteady forces and moments experienced by the wing. The appropriate choice in reference velocity, when the surrounding environment is composed of large spatial variations, was found to be critical in characterizing the wing's unsteady response.